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Understand the difference between enteral and parenteral nutrition

Plus it's really expensive (to produce and administer because it's sterile ANDneeds to be given with a needle)

Can even lead to intangible costs, like psychological changes

It's annoying to the patient (invasive)

And complications can arise, like phlebitis (inflammation of veins) or infections

etc.

Important point: Use the gut if you can, or as soon as possible. If the gut is partially

working, use it as much as possible. This is to prevent loss of function in the gut.

Terminology (might want to skip this and read this as a summary)

Parenteral nutrition is nutrients given from a route outside the gut (see below)

Total Parenteral nutrition (TPN) is where the patient gets 100% of their nutrients,

needs to be a large volume and is completely water soluble. We will preparethese quite frequently

Peripheral nutrition is smaller volumes delivered via a peripheral vein

Nutritional support is delivering a constant stream of nutrients to the blood (can

be either enteral or parenteral) for special cases like cystic fibrosis (can't get

enough nutrients quickly due to thick mucus layer)

Basic differences

Basically, enteral means through the gut (GI system), while parenteral is

anywhere but the gut

Orally

Different tubes (e.g. nasogastric tubes)

Stoma (piece of gut is exposed to the environment)

Enteral could be given:

Generally more suitable for larger volumes which are not iso-

osmolaric

Therefore, can be used for long-term Total Peripheral Nutrition (TPN,

where all their nutrients are delivered this way)

Patients may have protracted diarrhoea, chronic obstructions (orpseudo obstructions) of the GI system, or short bowel syndrome (too

much GI system cut out due to surgery, think about inflammatory

bowel conditions like Crohn's disease or ulcerative colitis)

Central line- Jugular or subclavian vein, but it's inserted via the arm

Generally suitable for smaller volumes, but must be iso-osmolaric

Therefore, used for short terms (like after surgery)

Peripheral line- out in the arm

Parenteral is generally giving via IV (can also be IM or IC) which can be at two

different sites

OVERALL: the goal is to get nutrients into the bloodstream of the patient. The gut

processes larger molecules into smaller ones, while parenteral nutrition focuses

on getting these nutrients directly into the bloodstream to bypass the gut

Aseptic Dispensing

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Contents of nutrition liquids

Both types of liquid will contain all the components of the food we normally eat,

such as carbohydrates, fats and amino acids, trace nutrients etc.

Enteral formulations are quite simple, being made from more complex moleculeslike proteins and long chain carbohydrates

In addition, because it's being added centrally, we need to make sure it's

compatible with the blood

Which means the fats need to be suitably water solubilised (as a

suspension) and the osmolarity may need to be adjusted.

Parenteral formulations need to have these complex molecules to be broken

down to simple molecules, BECAUSE the gut is being bypassed (remember: the

gut is normally responsible for the important function)

Understand the importance of adequate nutrition in debilitated patients whether in

hospital or in the community.

You need to eat, it's kinda important.

Effects of malnutrition

So obese people are technically malnorished due to a lack of balance

Malnutrition is where a proper balance of nutrients isn't achieved

Leads to breakdown of various proteins and organ failure

Patients can be in a catabolic state, where their body is breaking down

proteins because the person isn't getting enough nutrients

Leads to tiredness, exhaustion and death

Patients could be in a normal metabolic state, but might not be getting

enough energy

There are two types of malnutrition we can look at

Costs of malnutrition

Slower healing times (longer visits are more expensive)

Increased chance of infection

Other complications, like muscle wasting (catabolic state)

Costs of product and production (aseptic production is costly)

Tangible

Psychological

Non-tangible

Refeeding syndrome

Arnold Lee

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Insulin secretion is tied to several electrolytes, such as potassium intake

into cells and phosphate

Leads to a reduction of electrolytes inside cells

After a long time of starvation, the body will adapt slowly to changes, such as

reducing the insulin secretion

Causes death due to a multitude of problems

If a person is suddenly fed a lot of food after this state, insulin secretion will kick

in and cause electrolyte imbalance (especially blood phosphate decreases due to

absorption into cells)

Appreciate the role of the pharmacist in an Aseptic Production Unit (APU) with regard

to parenteral nutrition

Aseptic versus Sterile

VERY important difference

Usually achieved with autoclaving or high temperatures etc.

Sterile is an absolute, a black or white state where the product contains no

contaminants whatsoever.

Does not guarantee sterility, but it's hoped it's sterile

i.e. this definition isn't as black and white when it comes to contaminants

Aseptic production is where a product is prepared from sterile products in a very

clean (aseptic) workplace.

Examples are bacteria, viruses or even fungi

Viable contaminants are able to grow and give someone an infection (can

lead to death by sepsis)

Examples are bits of glass or dustFILTERS ARE IMPORTANT, they keep them out to prevent this issue

Non-viable contaminants can't grow, but still cause problems, such as

occlusion of blood vessels or may be pyrogens

Contaminants come in viable and non-viable flavours

TPN bags

May be divided into three compartments (glucose, amino acids and fat

compartment) for enhanced stability. Must be combined before use

Note: after combination, inspect bags for creaming of the lipid suspension

(this is where the suspended lipids gather together to form larger particles,

might kill your patient if given)

TPN bags contain a liquid for TPN

TPN bags can generally be purchased and given in that state

Gives a lot more flexibility, tailoring it to specific patient requirements, but

this is very costly due to running the APU and hiring a pharmacist to make

it.

But they can be individualised within an aseptic production unit (APU)

Understand the principles behind aseptic preparation AND Be familiar with basic

aseptic manipulation

Skin particles carry stuff

We could cough or sneeze stuff outTherefore, we need to wear appropriate protective equipment

We are the number one source of contamination

Regularly checked to see if it's clean (taking swabs to see if anything will

grow)

Within the APU is a clean room

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Air is filtered

Everything is flush against the wall (no overhangs or anything)

Horizontal cabinets blow air towards you, protects the product only (which

means it can blow nasty chemicals like cytotoxics in your face)

Vertical flow cabinets will blow air downwards, protecting both the product

and the operator.

A laminar air flow cabinet is in these clean rooms

Generally speaking, these points are where the liquid is going to touch theequipment

This includes needle/syringe/filter tips, the inner ribs of the syringe etc.

Make sure you don't touch critical points

Reconciliation is where the products taken into the clean room are

matched with what's leaving the clean room.

This is in addition to other standard operating procedures, error reports,

GMP requirements etc.

Make sure the paperwork gets done

There's a window which allows you to observe and check on the tech.

NOTE: the person in the clean room might be a technician. Therefore, we are

responsible for anything they do

Why is safety important?

These cytotoxics are carcinogenic/toxic so we need to protect the people

handling these compounds

Protect staff

Prevent complications

Protect patients

Administration

Short infusions for cytotoxics (or peripherial nutrition) need to be

controlled specifically by a pump

Advantage is this allows for greater mobility, can let them go home

instead, saves the hospital money.

Longer infusions (such as for TPN) can also be controlled by a pump, or

they may use an elastomeric pump, which uses rubber to push liquids at a

slow rate.

TPN or cytotoxics are usually not delivered by the pharmacist, but they need totell these people how to.

Potentially fatal mistake with vesicants (blistering agents)

"Not for intrathecal (spinal)" use is NOT acceptable. Use "For IV use

only"

Be as specific as possible

Be careful to check it's the right patient, dose etc.

Because we need to tell how these medicines are used, we need to be very clear

when writing labels

This is where the IV fluid leaks out into the surrounding tissues (so it's

called being 'tissued' by nurses)

Patients need to be told to report discomfort or pain ASAP

In the case of vesicants (blistering agents) this can cause massive necrosis.

Be wary of extravasation

Intrathecal drugs tend not to be given very often, so the pharmacist incharge will personally deliver it to prevent mistakes

Also, you can only give a few millilitres via the intrathecal route (larger

volumes are used for IV route), so the size difference should tip off the

nurses as well

Note: For intrathecal drugs

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Patient Information

Such as for extravasation

Or if the elastomeric pump breaks at home

How to counter side effects (like anti-emetics for vomiting)

Need to tell the patient what to do

Can vary greatly between patients and within patients

e.g. changing organ function, reduced effect or tolerance etc.

Doses

Biological (contamination)

Chemical (reactions occurring)

Physical (precipitation or light sensitivity)

Stability

Allergies

Pregnancy (debatable, risks to foetus need to be considered)

Contraindications

Check for:

We need to know what can happen, and may have to advise on how tocounter them

Important information is the side effects which will affect the patients

Adverse reactions

Note: REMEMBER, the cytotoxics will usually affect growing cells. These side effects are

usually caused by affecting dividing cells like the bone marrow or mucosal surfaces etc.

Oral and GI mucosal damage due to cytotoxics affecting their regeneration

and repair

Oral hygiene becomes much more important

Patients need to report abdominal pain or bleeding

Mucositus

White blood cells and platelets are reduced by cytotoxics

Must report bleeding due to reduced platelets

Can also cause neutropenic sepsis (means low neutrophils plus infection)

where temperature is high, chills, sore throat, pain on urination etc.

Myelosuppression/immunosuppression

Lysis of tumour cells releases calcium, uric acid and potassium

This can lead to gout, need to treat with allopurinol and keep hydrated

Tumour lysis

Hair grows back wavy

Usually temporary and not harmful, but don't let the patient be surprised

Alopecia

Be competent at calculations

Sometimes we might be adding extra nutrients or electrolytes to the TPN bags for

specific requirements for the patient. So we need to be able to make calculations.

Generally, we already have these electrolytes in a solution, so we need to know what

volume of these liquids we're adding.

Try to understand why the calculations/formula works. Saves you from having to

rote learn AND helps to pick up on any mistakes

Potassium ions can be supplied by potassium dihydrogen phosphate or

Watch out for other sources of electrolytes!

General tips:

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So when you're adding phosphate, you have to add potassium

potassium chloride

The TPN bag might come with some electrolytes, make sure you take away

these electrolytes from your calculations

Premade TPN bags can generally hold 20% more fluid /)^3^(\

In other words, adding calcium gluconate just after potassium dihydrogenphosphate (or vice versa) will lead to calcium phosphate formation

This is VERY BAD, because calcium phosphate is insoluble, it will block your filter

or piss off your patient with phlebitis if you don't kill them first

Don't replace filters, they can cost $5US per filter

To avoid this problem, just use another solution first (like sodium chloride if you

have to add it) OR just rinse with water for injection

Important consideration: Calcium phosphate WILL form if calcium ions are in contact

with phosphate ions

Example calculation

A patient needs 68mmol potassium ions and 40mmol phosphate ions in the TPN bag.

The TPN bag already contains 48mmol potassium and 20mmol phosphate. You havethe following solutions available:

Potassium chloride 2mmol/mL (contains 2mmol/mL of potassium)

Potassium dihydrogen phosphate 1mmol/mL (contains 1mmol/mL of potassium and

phosphate)

What must you do to fulfil the prescription?

Start off by calculating how much of each electrolyte you need. In this case, the TPN

bag already contains some of the electrolytes, so we need to subtract them:

Potassium: 68mmol - 48mmol = 20mmol

Phosphate: 40mmol - 20mmol = 20mmol

We can see both are short by 20mmol, but we have two solutions we can use.

We can't use potassium chloride, otherwise we'd have an excess once we try to add the

phosphate because the phosphate solution also has potassium in it.

Lucky for us, the shortage is a 1:1 ratio, so we can just use the potassium dihydrogen

solution only to make up the 20mmol shortage.

Now, we know each 1ml of the solution contains 1mmol of both potassium andphosphate, but we need 20 mmol of both, so we divide 20mmol by 1mmol/mL

20mmol / 1mmol/mL = 20mL

Notice how the units will fit (mmol will cancel each other out, and since the ml is on the

bottom, it gets flipped up after division), showing you did the right type of calculation

So the answer is we need to add 20mL of potassium dihydrogen phosphate to the TPN

bag to fill the prescription.

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Objective: Understand the biological basis of cancer

Tightly regulated with several checkpoints

Cell division occurs through the cell cycle

The process is called oncogenesis

Suppressor genes

Proto-oncogenes/ Activator genes

Associated with two families of genes

Cancer occurs because cell growth becomes unregulated

Inherited

Chemical

Physical

Infectious

Several factors are known to damage cells to cause them to have their growth

unregulated

Summary

The cell cycle

G0- "Growth 0" phase. The cell is at rest, no division is occurring (lots of cells are

like this in the body, as they are terminally differentiated)

The instruction can be from a hormone, growth factor, a change in local

conditions etc.

G1- "Growth 1" phase. The cell prepares to divide, BECAUSE it's received an

instruction to divide. As a result, it will now synthesise proteins and enzymes

required for division

Antimetabolites, such as methotrexate will work here

S- "Synthesis" phase. The cell will now replicate DNA. This is the longest stage

clocking in at 6-8 hours.

G2- "Growth 2" phase. The cell has two copies of DNA, and it will now produce

proteins required for mitosis to occur. Takes 2-3 hours.

Oncogenesis

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Antimotility agents, such as paclitaxel will work here

M- "Mitosis" phase. The cell will now split, taking one copy of the DNA, to

produce two identical cells. This is the shortest phase, clocking in at 1 hour. The

cell will now return to G0 phase, and can re-enter the cycle if stimulated.

A homeostatic mechanism exists in the body to keep things under control

Cells will be killed off due to apoptosis over time

While other cells will be triggered to grow to replace these dying cells

Normally, we would expect the number of dying cells to equal the number of

cells created to keep the number of cells in the body constant

So the cell cycle is tightly regulated to stop this from happening

If the homeostatic mechanism fails, then we get cancer.

Cell division checkpoints

DNA damage is harmful to cells, as it can cause a loss in function, which includes

not making a correct protein, or it could even become cancerous.

Once that mutation passes down through the cell cycle, it becomes fixed

into the DNA permanently, because the cell doesn't have an original copy

of the DNA to check against.

Therefore, cells have defence mechanisms against mutations from being passed

down during mitosis

G1 arrest- the cell cannot enter the cell cycle

G2/M arrest- the cell cannot enter mitosis

If the cell fails to pass the checkpoint test, the cell cycle is immediately

halted to allow for repairs to occur before continuing:

If the DNA cannot be repaired, the cell will undergo apoptosis

So the cell cycle has several 'checkpoints' where the integrity of the DNA is

checked to stop mutations from occurring.

p53 is especially important, as it is a part of the G1 checkpoint, can induce

DNA repair and induce apoptosis if needed

Therefore, many tumours will have p53 deactivated

p53 and the Rb (retinoblastoma) genes are important in cell cycle control, as they

will regulate the cell cycle.

Telomeres are straight pieces of DNA at the end of a chromosome

The straight ends cannot be perfectly copied, so they shorten with each cell

division

Once the telomeres are short enough, the cells are triggered to undergo

apoptosis

The reason for this is to make sure cells have an automatic 'expiry date' to

prevent them from accumulating too many mutations, and becoming

cancerous.

Therefore, it's also another common mutation seen in cancers

To counter this, a cancerous cell can activate telomerase, which increases

the length of the telomeres to prevent apoptosis from being triggered

Another important mechanism is the use of telomeres

Oncogenesis

Remember: the cell cycle is tightly regulated, so the cell has quite a few

barriers which it needs to overcome to become cancerous

For example, to become cancerous, the cell would have to ignore apoptotic

signals (p53), grow independent from growth factors, have factors to

promote angiogenesis (production of blood vessels), avoid the immune

An important fact is one mutation is not enough to cause cancer

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system etc.

But if the checkpoints are non-functional (either inherited or mutated),

then it's much easier for these mutations to occur, so it's easier for the cell

to become cancerous

REMEMBER: normally a person will carry two copies of the gene, both must

be broken to get cancer ('dominant' gene, so hetrozygous people are still at

higher risk of getting cancer as a result)

Normally, these mutations will be prevented by the checkpoints put in place

If you live long enough, by chance you will accumulate enough mutations

Because the cell needs multiple mutations to become cancerous, cancer is adisease which is concentrated in the elderly

Suppressor genes

Activator genes (proto-oncogenes)

Also, there are two main groups where mutations will cause cancer, as they are

important for regulation of cell growth:

p53 is again an important suppressor gene, as it contains apoptosis genes

If BRCA is mutated, the incidence of breast cancer shoots through theroof

BRCA is an important suppressor gene as it is involved in double stranded

DNA repair

Anything inhibiting growth, such as growth regulator genes are important

Contact inhibition genes- normally these will stop cells from dividing if they

are in contact with each other, as it indicates there's no space to grow.

Suppressor genes will work to prevent cancer, so these should be kept ON

Angiogenic genes are very important in tumours, as the tumour must be

able to get a blood supply set up to grow properly. Otherwise the tumours

will be small and most likely unsuccessful.

Some genes will allow cells to escape immune surveillance, or be

immunosuppressive

Others will help them survive outside the tumour, which allows distant

metastasis to occur (surviving outside the original tumour is quite difficult)

Activator genes are also called proto-oncogenes, as normally they are not

cancerous, but if mutated, will cause cancer. Therefore, to prevent cancer, these

should be kept 'INACTIVATED' (not completely off, normal body function might

need them, like healing)

How do we get cancer?

As stated before, you need functional suppressor and non-activated

activator genes to NOT have cancer.

Sometimes, people will inherit a non-functional copy (or copies) orsuppressor genes

Or receive one (or two) copies of an activated activator gene

Think about it as they've already accumulated mutations required for

cancer.

Therefore, these people are at a higher risk of getting cancer

Inherited

Carcinogens are chemicals which will cause damage to DNA (either directly

or indirectly through metabolites/breakdown products)

Again, these mutations need to hit a suppressor or activator/proto-

oncogene.

Chemical

Direct damage to DNA

Ionising radiation

Non-ionising radiation

Physical

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Damage via production of radicals

Either will cause DNA damage, which might give you cancer if the wrong

genes are turned on/off (see above)

Quite a range of viruses can do this

Why? Because p53 can trigger apoptosis and ruin their plans

Human Papillomavirus (HPV) and Epsein-Barr virus

Can inhibit p53

This is probably why hepatitis B and C cause liver cancer

Cause increased division, which leads to more chances of being mutatedand causing cancer

Yeah this can only end badly

Seen by retroviruses (can enter the host's DNA) like HTLV-1 or HIV

Insertion into oncogenic gene

Infectious agents

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Chronic inflammation can cause cancer

The immune system can kill cancerous cells

Can be thought of having a role before AND after cancer

The immune system has a role in cancer (surprise!)

Chronic inflammation and oncogenesis

Inflammation produces some reactive oxygen species which may damage

DNA, causing activation/inactivation of genes

Inflammation also encourages division of some cells (especially immune

cells) which can lead to cancer

It appears chronic inflammation can cause cancer

NSAIDs have some effect for protecting against cancer

Therefore, anti-inflammatory cytokines or chemokines may be used to prevent

cancer.

Immune response AGAINST cancer

Destroys the infectious agent which can cause cancer

Kills any cancerous cells before becoming a tumour

How is the immune system protective against cancer?

Neutrophils, macrophages and dendritic cells

Detect foreign cells, and abnormal body cells (due to infection or

cancer) to trigger an immune response (produce cytokines and stuff),especially trigger the acquired immune response

Slow down the infection long enough for the acquired immune

system to kick in

Innate immune response is the first-line protection mechanisms

T Lymphocytes for a cellular immune response, B lymphocytes for a

humoural (antibody) response

Produces more effective killing cells (natural selection, where

lymphocytes with the best receptor against the antigen is stimulated

more)

Produces memory cells to prevent long term recurrence

Acquired immune response is the killing blow

The requirement of a danger signal will also prevent any self-reactive

cells from being activated as well

Self-reactive cells are killed off during thymic selection to protect the bodyagainst auto-immune reactions

Recap: innate immune response vs acquired immune response

All nucleated cells are able to get cancerous

But all nucleated cells must express MHC-I

The MHC-I is continuously recycled from displaying an antigen and being

drawn back into the cell to find a new antigen to display

Normally, the immune cells will see all the MHC-I receptors displaying

normal body antigens

But if the cell becomes cancerous, it might start producing antigens the

immune system can't recognise

This will lead to an immune response, and destruction of the cancerous

cells

So How does that help against cancer?

The role of the immune system in cancer

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Because it's MHC-I, it needs the CD-8 co-receptor to stimulate CD8 T

cytotoxic cells

Therefore, the immune response will be mainly carried out by CD8 T

lymphocytes (cellular response)

What kind of immune response?

Well, it's not the same as the diseases we've seen in the pastTumours will make 'Tumour specific antigens' (TSA) which are the mutated

proteins the immune system can't recognise

In addition, they might also make 'Tumour associated antigens' (TAA) ,

which is where the tumour produces proteins which shouldn't belong in

that part of the body

Lastly, an infectious agent can be causing cancer, these cells will display

viral antigens to become a target for the immune system as well.

Don't we have to worry about auto-immune reactions?

Danger signals can come from infected cells at least

Also, if a tumour does form, then the centre of the tumour may becomenecrotic due to reduced blood supply to the region. The immune system

will respond to necrosis with inflammation.

If cells are kept in anergy, how do we activate them against cancer?

Plus they are more likely to be subject to mutations due to

inactivated suppressor genes.

Tumours will be subject to natural selection, because vulnerable

cancerous cells will be killed off easily, leaving cells which are

resistant to immune attack

They can look normal to the immune system by expressing normalantigens on MHC-I

They can shut down antigen presentation (however, see below)

They can produce an environment which can be immunosuppressive

Maybe but cancers can have immune defences

Immunosuppressed due to drugs, infectious agents or radiation

Plus as people get older, their immune system strength decreases

Or the person just can't mount a response

The immune system decides to induce tolerance against the tumour

cells, preventing any immune cells from attacking it

Or the tumour cell or supporting cells will produce

immunosuppressive factors like cytokines

So one important result of treatment (radiation, chemo or surgery) is

to kill off these immunosuppressive cells and let the immune system

clean up

Or the person produces the wrong response

So our immune system should work against cancer effectively right?

It's one method to prevent the immune system from noticing

But Natural Killer (NK) cells will be able to detect if a cell is missing MHC-I

NK cells are always set to kill, so they need an inhibitory signal to prevent

the cell from being killed

MHC-I provides the inhibitor signal, so cells with MHC-I will survive

Cells which do not produce display MHC-I cannot send the inhibitory signal,and so they will die.

What if the cell stops producing MHC-I?

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Why is it difficult to treat cancer?

Narrow therapeutic range due to targeting the same pathways used by our

healthy cells

We can counter this by combining several drugs at lower doses to prevent

extreme toxicity

The amount of cells we can kill is limited by toxicity

Leads to increased drug resistance

Use multiple drugs to help to prevent increased resistance

Cells are rapidly dividing, and the genomes are prone to mutation due to damaged

repair/error checking mechanisms

Brain and testes

They can escape to safe sites in the body, where it is hard to get drugs or immune

involvement in

Therefore, we need to apply chemotherapy as soon as possible

By the time we're treating the cancer, it's already growing slowly, and is less

receptive to chemotherapy

Combination therapy

Again, results in better response (synergy) and reduced side effects and a lowered

chance in gaining resistance

Each drug should work against the cancer

Each drug should have a different mechanism of action

Drugs should avoid overlapping toxicities

AND include a few which are non-cycle specific

Reason for this is because only a certain portion of the cancerous cells

will be in the part of the cell cycle, combining the two leads to a better

outcome

Target different stages of the cell cycle

There are a few principles you should keep in mind:

Infusion over time or frequent dosing

Think of it like the time-dependant kill antibiotics, a long period of

time is preferred

Cell cycle specific drugs need to achieve high concentrations over a long

period of time, as different cells will enter that specific part of the cell cycle

at different times.

One fast infusion

Think of it like the concentration-dependant kill antibiotics, where the

highest concentration needs to be achieved

While non-specific agents just need to be given in one single high dose

The dosing of a cell cycle specific vs. a non specific agent is different:

Surgery causes injury which stimulates cells to come out of G0

Therefore, can hit more of the cancerous cells

Cell cycle specific drugs should be coordinated with surgery

Allows the body's normal tissues to recover from the chemotherapy

But the waiting time between treatments is short enough to prevent the

cancerous cells from

Drugs are given in treatment cycles

Pathways for antimetabolite drugs to target:

Pharmacology of cytotoxic drugs

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Also inhibits thymydilate synthase (TS) as increased DHF building up in

the cell will actually inhibit TS

Inhibits dihydrofolate reductase (DHFR)

Stops the conversion of dihydrofolate to tetrahydrofolate to stop the

production of all nucleotides

Countered by the cancerous cells by increasing efflux transporters (such as

P-gp)expressed on the surface of the cell to remove MTX, or due to a

mutation or upregulation in DHFR

Methotrexate (MTX)

Inhibits Ribonucleotide reductase (RR)

Stops the conversion into deoxyribonucleotides, as that's the form needed

to be incorporated into DNA

Hydroxyurea

Inhibits IMP dehydrogenase (IMPDH)

Stops purines from being made (A as AMP and G as GMP)

6-Mercaptopurine (6-MP)

Inhibits thymidylate synthase

Prevents the conversion of dUMP to dTMP to cause a thymineless death (a

pyrimidine)

5-Flurouracil (5-FU)

Not shown above

Inhibits DNA polymerase

Stops nucleotides from being added to DNA to stop production

Cytarabine

Azathioprine and 6-MP metabolism

Azathioprine is metabolised to 6-MP

Highly polymorphic

Fast metabolisers will produce too much toxic side products

6-MP is metabolised by TPMT (Thiopurine methyltransferase)

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Slow metabolisers will accumulate 6-MP leading to toxicity

This is the enzyme which is inhibited by allopurinol

6-MP tends to be given to patients who need allopurinol to combat tumour

lysis syndrome

Adjust dose of 6-MP down to compensate

6-MP is also metabolised by xanthine oxidase

Folinic acid

Not to be confused with folic acid

Folinic acid can be converted by another enzyme to several different forms, like

THF or MTHF, which can readily be used by the cells of the body

If it is used with 5-FU, it enhances the cytotoxic effect, as MTHF, a cofactor for the

thymidylate synthase enzyme is required for binding and inhibition

Methotrexate depletes useable folate reserves (as THF) as dyhydrofolate

reductase has been inhibited

i.e. stops DHF from being recycled into THF

Cancerous cells are too damaged by this point to be saved by this

folinic acid rescue

Folinic acid rescue after methotrexate use will allow healthy cells of the

body to produce nucleotides to prevent side effects

BUT it could also be used with methotrexate.

Mitotoxicity hypothesis

DNA damage in normal cells will lead to apoptosis

Therefore, the point of using of agents is to try and stimulate the cancerous cells

to undergo apoptosis

p53 induces apoptosis, it is a part of the G1 checkpoint of the cell cycle

These cancers are responsive to treatment, as p53 induces apoptosis

Leukemias and lymphomas

Some cancers will keep a normally functioning copy of p53 (wild type)

Minimally responsive to treatments

Lung, pancreatic and colon cancers

Other caners will get a mutation in p53, apoptosis isn't easily induced

Problem is, it depends on the function of certain genes/proteins like p53

Telomeres

2-30 kilobases which repeats 'TTAGGG'

A 50-300 base single stranded section will loop back onto the DNA and forma stable loop (t-loop)

Caps at the end of chromosomes

DNA polymerase isn't able to copy this section perfectly, it shortens with each

replication

Therefore, old cells which may have gained a lot of mutations won't be

allowed to grow anymore

Once it reaches a critical length, p53 steps in and prevents the cell from passing

the G1 checkpoint, forcing the cell into senescence (remain in G0 forever)

Inactivated version of p53 and

Activation of telomerase, which is an enzyme which adds to the length of

telomeres, making them grow again.

But cancer cells can get around this:

These two mutations will cause a cell to become immortal

Photodynamic therapy

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Experimental therapy which has drugs which produce reactive oxygen species

when exposed to light

Looks like iron contained within a polyphoryn ring

When struck by light, the iron will catalyse the production of free radicals

Allows for some targeting to specific sites of the body

DNA repair systems

Caused by natural errors

Mutations can lead to colorectal cancers

Mismatch repair

Single strand breaks (caused by alkylating agents and irinotecan)

BRCA1 and 2 are slower as they are made for double strand breaks

PARP1 repairs these, but if it is inhibited, BRCA1 and 2 can take over

Base excision repair

Addition of substances (such as alkylating agents)

Nucleotide excision repair

Double strand breakages (topoisomerase inhibitors and bleomycin induces

this, along with cross-linked DNA due to alkylating agents)

Homologous recombination repair assisted by BRCA is the best bet, which is

where the sister chromatid (remember you carry two copies) lends its

information to help join the two strands together

Non-homologous end joins is less safe as there's nothing to check against

Double strand break repair

Topoisomerase I inhibitor- irinotecan

Relieves coiled tension within the DNA strand (double helix)

Topoisomerase I is involved in uncoiling the DNA prior to replication

The enzyme will separate the two strands of DNA

Cuts one strand

Unties the strand by passing it over the other strand

Joins the two cut pieces together to complete the unwinding

Current model for inhibition is:

Actually is metabolised into SN-38 which is 1000x more active, but it's highly

protein bound and has a very short half life

It is cleared by UGTA1, which is lacking in Gilbert's syndrome. Stops the

SN-38 from clearing, leading to severe myelosuppression

Irinotecan will stop the ends from being joined together, leading to a single strand

breakage

Topoisomerase II inhibitors

Relieves coiled tension BETWEEN DNA strands (not within the strand)

Relieves supercoiling of DNA

Cuts both sides of the DNA strand

Passes the strand past another strand to relieve the supercoiling

Joins the two ends back together

Similar action to above

Some drugs like anthracyclines will allow the double strand breakage, but won't

allow it to come back together

Anti-mitotic drugs

Important during the M phase to pull apart and drag the chromosomes

Attaches to tubulin, which makes up microtubules

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Both classes of drugs lead to peripheral neuropathy

Also important for intracellular trafficking of chemicals with vesicles

Vinca alkaloids bind to the positive end of beta tubulin to prevent polymerisation

of the chain

Taxanes on the other hand will bind to the side of beta tubulin. It allows

polymerisation, but not depolymerisation (so it become stuck)

HER2 and Imatinib (and other signalling pathway blockers)

Some cancers will have unregulated growth due to expressing growth receptors

We can block these receptors to prevent growth

Use Herceptin (trastuzumab)

HER2 is a receptor which can be expressed in breast cancer

Imatinib blocks a tyrosine kinase associated receptor to prevent growth in Chronic

Myeloid Leukaemia

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Intro

Otherwise, the chemo can kill the patient before it kills the cancer

We want to specifically kill cancer cells over normal cells (selective toxicity)

Compared to antibiotics, which exploit differences in biochemical pathways

between us and them

Problem is, cancerous cells tend to use the same biochemical pathways as normalcells, which is why it's very toxic

Some normal cells are rapidly dividing (gut, bone marrow, liver) so they are

affected by chemo

But some cancerous cells won't divide rapidly, so chemo won't work well

against them

So we tend to target rapidly dividing cells to target the cancer

Leads to more drug resistance and treatment failure

Rapidly dividing cells are bad for treatment, because they tend to accumulate

more mutations

But it's limited by the toxicity of the drugs

We want to maximise kill count (hopefully on a log scale)

Oral forms are desired

Finally, we also want to have them in a form which is easy to administer

Vesicant- a substance which is able to cause blistering. Quite a few chemo drugs tend to

be vesicants. This is why patients need to be told to look out for redness, swelling,

discomfort or pain around the infusion site.

Alkylating agents

Can't copy or transcribe information from DNA

Trigger apoptosis due to damage

Guanine is generally targeted due to its nucleophilic properties (see below)

Designed to interfere with DNA function

Guanine is alkylated, so there's this massive group attached to it

This can lead to the elimination of the group as well (the base comes

off the DNA, see below)

Either way, the DNA can't work this way, so excision repair enzymes

are activated, to cut the DNA to replace these faulty bases

Because repairs can be made, this isn't effective

Modification of DNA bases (mono-alkylation)

See below for the structure a sulphur mustard

Notice it has two chlorines, so it can alkylate twice

Between chains

Within chains (more common)

It can form covalent bonds either:

This will prevent the DNA from coming apart normally for normal

function

Effective

Cross-linking within and between DNA strands (di-alkylation)

Normally, we'd except A goes with T and C goes with G in DNA

But alkylated G can go with T, which is a mistake

This will lead to mutations

Which can lead to a malfunctioning cell, and apoptosis

Nucleotide mispairing

How does it work? (mode of action):

Medchem of cytotoxic drugs

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Janus is the Roman god of doors. He has two heads, one pointing inside, and

the other pointing out.

People may have secondary tumours which are completely different

to the original tumour after a few years of treatment

Why is this important? Because alkylating agents will kill cancerous cells BUT

because they interfere with DNA, they can also CAUSE cancer.

Exhibits a 'Janus' effect

Below is a sulphur mustard, where there's a two carbon bridge between theS and the chlorines. THIS IS IMPORTANT. RECOGNISE THIS.

Sulphur mustards are gases, due to low intermolecular bond strength (they

don't H-bond to each other) so they are too dangerous to work with

So nitrogen mustards were investigated, because they can H-bond to each

other, so it's not a gas anymore, so it's safer to handle

The alkylating agents will always have a specific moiety

The two nitrogens in the right side ring presents a electron rich regionThis makes it nucleophilic, attacking the alkylating agent (seen as R)

Can lead to the ring opening which permanently binds the agent to

the base

Or can cause the entire group to come off as a leaving group from the

DNA

This addition will lead to a positive charge on the nitrogen, which needs to

be removed.

But remember: monoalkylation (shown below) can easily be repaired

Why is guanine (N7 nitrogen) targeted specifically?

The electronegative chlorine atoms will draw electrons towards itself,

causing the adjacent carbons to become slightly positive

Chlorine is a good leaving group as it comes of neutral with respects to

acid-base chemistry (i.e. even though it's negatively charged, it

doesn't have acid base chemistry)

The non-bonding electron pair (NBP electrons) on the nitrogen is attracted

to the positive charges, leading to intramolecular nucleophilic attack (SNi)

The mechanism of action of alkylating agents is all the same (and we need to

memorise it)

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Bond angles are strained (at 60 degrees instead of normal 108)

Both carbons are positively charged

The SNi leads to the formation of the aziridium ion, which is a highly reactive

electrophile (i.e. susceptible to nucleophilic attack)

Remember: the molecule is bifunctional as it has two carbons, so it

can crosslink DNA (deals more damage)

After nucleophilic attack with the nucleophile (which is likely to be guianine),

the base is now alkylated.

Forms the aziridium ion too easily then, which will just react with all the cells

it comes into contact with

So we need to tie up those NBP electrons to stop forming the aziridium ion

as easily to reduce toxicity, to reduce side effects

If the nitrogen mustard shown above had an aliphatic R group, it is too toxic to use

in people

Alkylating agents- examples

Mephylan

The NBP electrons on the nitrogen are partially taken up into the aromatic ring

It's actually L-phenylalanine (amino acid) attached to the mustard

The sterochemistry on the carbon is R

But it's still actively taken up by all cells, leading to side effects

They thought the phenylalanine would allow the drug to be taken up into growing

cells because it's an amino acid

If the phenylalanine comes off, it's still active because the mustard is intact

If the amino or carboxylate groups are metabolised, again, the mustard is

still intact and it's still active

This drug has some activity, because the NBPs are somewhat available

This is the really important one because we use it quite often

Cyclophosphamide

R

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It is a prodrug, it must be metabolised first:

In fact, the structure shown on the right can be further broken down to form

just a bare nitrogen mustard, which is thought to have most of the activity

The NBP electrons in Cyclophosphamide are completely taken up into resonance,

so no aziridium ion formation can occur, so there is no alkylation.

Need to co-administer with Mesna and make sure to keep the patient very

well hydrated with IV fluids and oral fluids

Mesna (pictured top left below) has a sulfate group purely for solubility and

salt formation, while the active area of the molecule is the thiol (SH) group,

which acts as a nucleophile to bind with the acrolein to form a non-toxic

compound

Problem with cyclophosphamide is acrolein is a side-product which is toxic

Some cancer cells produce a great amount of glutathione (GSH)

Remember: thiol is a nucleophile, the active aziridium ion form is very

attractive

GSH has a thiol group, which can react with the alkylating agent before it

reaches the DNA to deal damage

Therefore, these cells will be resistant to treatment

Thiol groups could also be a hindrance to treatment though

An alkylating agent may be conjugated to a steroid to help it get into specific

cells

It is only effective in cells which have low ALDH (aldehyde

dehydrogenase), which are the well-differentiated blood cells, while

the stem cells of the blood are quite high in ALDH, so they tend to be

protected

Cyclophosphamide is actually quite targeted if you think about it

Lastly, some forms are slightly selective

Alkylating agents- Methansulfonates

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The oxygens are strongly electronegative, causing a great positive charge on

the sulfur and adjacent carbon

Busulfan has two methanesulfonate groups (the two sulfur containing groups on

the sides)

The methanesulfonate group is a good leaving group, so the carbon with thepositive charge is able to attack guanine as well

But because it's got two groups, its able to cross link DNA

Alkylating agents- nitrosoureas

These are the drugs which tend to end in 'mustine'

Very useful for brain cancers, as they are lipophilic enough to pass through the

BBB

Because the non-bonding pairs of electrons on the nitrogen are completely

taken up into resonance, so the aziridium ion can't be formed

Although they look like normal alkylating agents, they don't have the same

mechanism

Instead, through a complicated mechanism, it breaks down to form two positively

charged carbocations which are the active molecules

Platins (alkylating-like agents)

These are not alkylating agents, but shows some similar action (crosslinking of

DNA)

The classical one is cisplatnin

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Cisplatnin is a square planar molecule, with 2 amine and 2 chloride groups in

a cis configuration:

This is because of this equilibrium reaction:

Interestingly, cisplatnin is formulated in normal saline (0.9% NaCl)

If the concentration of chlorine is high (as it is in the blood and in normal saline),

then the equilibrium lies to the left, which is the inactive form

Therefore, platnins are prodrugs

However, if cisplatnin moves into the cells, the chloride concentration is much

lower, the equilibrium moves to the right, and the activated 'aquated' form is

produced (pretty much water chucked on)

The H2O ligand is a very good leaving group

The aquated form is active, because the platinum atom can now attach to the N7

atom of guanine (just like alkylating agents)

However, this is a intra-strand (within strand) crosslink.

This will cause the DNA to have a 90 degree kink due to the shape of

cisplatnin (square planar)

This irregular shape means the DNA is now useless

Because there are two chloride groups, the same process will happen again, whichcauses DNA to become cross-linked

GSH will also bind to platnins to make them useless

We can try to shield the platnin with a bulky group, but this is ineffective

Again, another huge problem is with glutathione

Therefore, we have newer, second generation platnins which are less

reactive/toxic but still just as effective

Cisplatnin is too reactive, it is quite toxic

It has a bi-dentate ligand instead of the two chorines

This slows down the aquation of the platinum, leading to reduced toxicity

Pictured above is oxaliplatnin, a second generation platnin

Antimetabolites

Self directed learning

Up to now, we've looked at compounds which deliberately damage DNA

But antimetabolites will cause DNA damage by preventing the synthesis of DNA,

either by producing false metabolites, or interfering with the enzymes responsible

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Therefore, this class of drugs are S phase specific for the cell cycle

for production

Responsible for producing thymine from uracil, uses tetrahydrofolate (THF)

as a co-factor

Disruption will mean thymine synthesis cannot occur, and the cell will

apoptose due to a thymineless death

The primary target enzyme is thymidylate synthase

Antimetabolites- 5-fluorouracil

5-flurouracil has a strongly electronegative group on the 5 position, which makes it

quite attractive to the enzyme

Note: he doesn't think it's a prodrug, because prodrugs tend to be

catabolised (broken down) to its active form. 5-FU is anabolised (built up) to

its final form due to the addition of ribose and phosphate

It is a prodrug (even though Schmerer disagrees), it must first be converted to its

deoxyribonucleotide form (pretty much just attach some phosphates to it to makeit look something like a nucleotide)

Normally the THF would react with the uracil to form thymine, but this can't

happen due to electrical repulsion between the fluorine and the nitrogen 10

of THF

When it enters the thymidylate synthase enzyme, it causes the formation of a

false complex with tetrahydrofolate (THF) and thymidylate synthase

This effectively prevents thymidylate synthase from being regenerated, which

stops thymine production

This causes the elongation of DNA to be stopped, leading to apoptosis

Additionally, these false nucleotides may also be incorporated into the DNA and

RNA

Anti-metabolites- folate metabolism

As stated above folate (as THF) is an important co-factor for thymidylate synthase

It needs to be reduced back to THF to be used again

After thymine is produced from uracil, the THF is oxidised to dihydrofolate (DHF)

It is able to be inhibited

Also causes a thymineless death

May be used as a synergistic drug with 5-FU, as they both target the same

process

The enzyme folate reductase is responsible for this function

Increases the electron density on the nitrogen at the bottom of the

ring, which is essential for binding

Therefore it will be able to outcompete folic acid

Better substrate compared to the endogenous substrate, folic acid due to

the amine group

Methotrexate will inhibit folate reductase

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Bleomycin

This is a problem, as it is hard to scale up to get large yields

Massive molecule which is synthesised by bacteria

Although a part of the molecule is cut off, DNA binding sites lie to the right

of the molecule shown below. However, it is unable to intercalate with DNA

due to too much 3D structure (need to be flat to intercalate)

The important bit is the iron in a square planar structure

Notice how the oxygen is bound to the iron, it displaces the carbamate

group

The oxygen is reduced to oxygen free radicals, which then damage the DNA

The action of bleomycin is to bind to the DNA and cause DNA breakages

The molecule is enzymatically cleaved by hydrolase, which reduces DNA binding

and damage

The copper is removed to inactivate the molecule to reduce toxicity (it will

find iron to chelate to in the body)

Normally, it comes as a blue copper complex (the copper sits where the iron is

sitting below)

It is amazing to see such a large molecule being able to enter the nucleus. The

sugars may be used as a recognition site to gain access to the nucleus

Because it converts oxygen into free radicals, the compound is associated with

oxygen toxicity, leading to pulmonary fibrosis. Need to monitor patients carefully

Actinomycin

Flat ring system which isn't fully aromatic. It is still able to intercalate to the

DNA

Composed of three basic parts:

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Causes free radical formation, which does have some effect against DNA,

but the problem is it also occurs in the cytosol of cells

This is why it might be causing cardiotoxicity, as the cells of the heart cannot

divide to form new cells, so the cells will take gradual damage over use

Therefore, there is a maximum cumulative lifetime dose for all the

molecules in the anthracycline family

They are also a target for reductase enzymes, this is a major issue

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Importance of targeted systems for chemotherapy

Chemotherapy drugs are generally not targeted at specific against cancer cells as

we don't have many biochemical differences between cancer cells and normal

cells.

Remember: treatments tend to be dose-limiting due to toxicity

Increasing dose due to better targeting leads to better outcomes

Reduced toxicity as the drugs won't affect normal cell function

Increased efficacy as more of the drugs will hit the cancerous cells

Therefore, if we were able to produce a targeted form, it would be better due to:

Levels of drug targeting

Broadest targeting

Targeting to the capillary bed of the desired organBetter than nothing

First order targeting

Targets at a cellular level

Hit specific cells within a region or in the body

Second order targeting

Targets a specific part of the cell

In our case, we want to target the nucleus of the cancerous cells to deal the

greatest amount of damage to DNA

Third order targeting

Physicochemical properties of the carrier/drug will help the drug reach its

target

In other words, the body won't active move the drug, it needs to be

designed to get there on its own

Analogous to passive diffusion

Examples are modifying pH or particle size

Passive targeting

Manipulate the body to actively take the drug to where it's needed

Analogous to active transportExamples are antibody based systems

Active targeting

To get these levels of targeting, we can consider two types of systems:

Ideal properties of a carrier

Non-toxic

Cheap

Specific targeting to the desired cells

Doesn't leak the drug while moving to the site of action (might be a liposome)

Drug must get to the site

Drug must be released at the site (otherwise the carrier will prevent it from

having its action)

Drug must remain at the site for as long as possible

Nano-particulates- encapsulates the drug to carry it to the site of action

Generally, there are two types of carriers:

Targeted Drug Delivery systems

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Liposomes- small spheres of phospholipid membranes which has drugs

inside (inside is a hydrophilic solvent)

Emulsions- small spheres of lipids which has the drugs in the lipid

compartment (inside is a lipophobic environment)

See case 1

Polymers

Proteins (make sure it's human protein to prevent an immune reaction)

Both of these have long half-lives to give it enough time to reach the site

See case 2

Drug-conjugates- drug is attached to the carrier to be enzymatically released at

the site

Barriers to drug delivery

Tumours are able to cause angiogenesis (required for growth larger than

1-2mm), but they can't produce a drainage lymphatic system

The blood vessels formed in tumours are very leaky due to increased gaps

between the tight junctions of the cells of the endothelium, this allows

liquids to move out

Liquids tend to be kept in the center due to a thicker extracellular

matrix in the core

Pressure tends to be highest at the middle of the tumour, pushing liquids

from the core outwards

Our drug can be pushed outwards due to this pressure, so chemotherapy is

most effective around the outside of tumours

High interstitial pressure in tumours

Perfusion is greatest on the outside of tumours where the growth is

occuring, while it is lowest at the core of the tumour, which may be

hypoxic and necrotic

Our drugs are delivered by the blood, so again, the surface of the tumour ismore affected than the core

Non-uniform perfusion

The membrane tends to keep bulky or polar substances from entering the

cell, so it's hard for our drug to get in

To make matters worse, the membrane is studded with efflux transporters

like P-gp which kicks out the drugs as soon as they enter

Cell membrane barriers

Glutathione- contains a thiol group (-SH) which is very attractive for

alkylating agents as it is also a good nucleophile. So our alkylating agents

will attack glutathione instead of attacking the DNA

DNA repair enzymes- if the cell can repair the damage the drugs arecausing, then it will be resistant to attack

Intracellular inactivation

Enhanced permeability and retention effect

Although the lack of a lymphatic system in tumours causes an increased pressure

within tumours, this is also an advantage to us

The enhanced permeability and retention effect means our drug is able to enter

the tumour easier, because the gaps between the tight junctions are wider

(remember, these carriers tend to be quite big)

And since there's no lymphatic system, the drug can't be washed away due to

lymphatic drainage, so it stays in the tumour for longer

Overall, this effect counteracts the increased pressure from the tumour

Case 1: doxorubicin in PEGylated liposomes

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Normal liposomes use phosphodialcholine to create the phospholipid bilayer

seen in liposomes

PEGylated liposomes will use a phospholipid with PEG (polyethylene glycol)

polymer attached to the polar end of the phospholipid

What happens is the PEG will be on the outside of the liposome, surrounding it

with this polymer

Low CmaxLow AUC

High clearance

Short half-life

Large volume of distribution

Normal liposomes will generally be ineffective, due to their poor

pharmacokinetic variables

PEG prevents the cells from detecting and phagocytising the liposomes

PEG prevents opsonisation, so it can't be picked up as a foreign component

PEGylated liposomes have much better pharmacokinetic variables, as they are

able to evade the reticuloenothelial system (macrophages and monocytes),

which is what causes the poor performance of liposomal compounds

Case 2: Doxorubicin-polymer conjugates (PK1)

Doxorubicin is attached to a polymer through an amino acid spacer

Too large to enter through normal tight junctions, but small enough to

enter through the leaky tight junctions of the tumour

Allows some targeting, as normal cells won't be able to take up this

conjugate easily

The polymer makes the particle size very large

Once the conjugate has reached the tumour, a tumour cell will take it up via

pinocytosis ('cell drinking')

Once it is inside the cell, the endosome (the vesicle formed from pinocytosis) will

be fused with a lysosome

The enzymes in the lysosome, together with the acidic environment of the

endosome will cause cleavage of the amino spacer between the doxorubicin and

polymer to be cleaved, releasing the free drug

The free drug is now free to move around the cell and cause damage as required

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Background

In adults it's important for healing and endometrial growth in females

In embryos, it's important to produce vessels from vasculogenesis (the

production of blood vessels from nothing)

Angiogenesis is the process where new blood vessels are formed FROM PRE-

EXISTING vasculature

Tumours need a supply of oxygen and nutrients which are delivered by the

blood

Can't get too big if there aren't any blood vessels supporting it

Tumours cannot grow any larger than 1-2mm if angiogenesis cannot take place

Therefore, antiangiogenic treatments are being researched

Mechanism

These factors are peptides, not other hormones

Wounded areas will produce angiogenic factors, like vascular endothelial growthfactor (VEGF)

These factors will bind to receptors on the endothelial cells of the blood vessel

Growth factors are then required to bind to other receptors to really kick off

angiogenesis by activating the endothelial cells

Activated cells will break down the basement membrane of the blood vessel to

form holes for new blood vessels to poke out of

The endothelial cells will then divide and poke out of the holes to travel towards

the injury site using adhesion molecules to drag themselves forwards

They then roll up to form a tube

Smooth muscle cells will then support the newly made blood vessel for structuralsupport

How does this apply to secondary cancers?

Tumours will produce an angiogenic factor to produce blood vessels

Luckily, this stops any secondary tumours from carrying out angiogenesis

But once they get big enough, they also secrete angiostatin, a natural inhibitor of

angiogenesis, normally used to prevent unnecessary angiogenesis

Once the initial large tumour is removed, this secretion of angiostatin is also

stopped

The concentration of angiostatin drops, which allows smaller tumours to grow,as they are able to form blood vessels now

Thalidomide

Mechanism of action is unknown

Has antiangiogenic effects

May be used in multiple myeloma as a last resort

Need to have effective contraception, as it is present in semen

Hormonal contraception/IUD or surgery PLUS condoms/diaphragm

Make sure no one can get pregnant

However, it is strongly teratogenic

Pregnant women

Women who are able to have children but are unwilling to use

contraceptive methods

Therefore is contraindicated in:

Antiangiogenic treatments

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Ditto for men

Monoclonal antibodies

Because it binds so tightly, it stops normal factors from attaching to

prevent angiogenesis

Cetuximab has a high affinity for the epidermal growth factor receptor, which is

used in angiogenesis

Expected side effect: reduced healing, irregular periodsBevacizumab is used in colorectal cancer, antiangiogenic as well

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Activates the immune system to kill the cancer

Therapeutic vaccines

Prepares the immune system to prevent cancers, generally targeting a factorwhich is implicated in cancers, like viruses

Prophylactic vaccines

There are two types of vaccines against cancer:

Human Papilloma Virus (HPV) vaccine

Prophylactic vaccines against the HPV virus has been shown to decrease the

chances of getting cancer

Gardasil works against four strains of the virus which have a high risk of causing

cancer

Because it doesn't protect against all strains, it doesn't completely prevent cancer

Mostly mild effects were seen (local injection pain etc) Some severe effects were rarely seen, but they were not specifically linked

to the vaccine

Considered to be safe

Requirements for a therapeutic vaccine

The host tends to be immunocompromised either due to the cancer or due

to the treatments

So they don't have enough immune function to respond to the vaccine

Host must be able to respond to the vaccine

Tumours tend to suppress the immune system to keep themselves going So we cut them out to reduce the suppression

Plus this generates inflammation, which kicks off the immune system again

Need to be able to overcome tumour induced immunosuppression

Easy immune target

Could be easy, because the cancer can produce some weird antigens due to

their damaged state

Could be easy to target just one, but there's a lot of targets

Could be difficult, because the cancer isn't just one type of cell, many

different cells could exist, displaying a range of antigens

The tumour needs to express antigens on its MHC molecules

Adoptive T cell therapies

We give the patient premade cells /antibodies

Their immune system doesn't do much while we do the work

We then introduce our specially made T cells from the lab, and sicc them on

the tumour cells

Passive therapy

Harder to get (need a biopsy of the region near the tumour

Expected that these cells have at least some activity against the

tumour

Near the tumour

Easier to get

Get more cells

Peripheral blood

We can get T cells from:

Then we have two culture methods:

Cancer vaccines

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The T cells are only exposed to one antigen isolated from the tumour

Growth factors are added to stimulate the clonal expansion of the cells

which are specific against that antigen only

So we've got a lot of cells which are similar as they all attack the same

antigen

Takes a lot of growth and exposure cycles to get a decent amount of

cells (6 weeks)

Antigen-specific stimulation

Take all the T cells and stimulate all of them to grow

Remove regulatory T cells while growing them

Cause a bit of genetic modification to get a wide range of T cells

formed

After a shorter period, we get enough cells (10 days)

Not all the cells are effective against the tumour, we haven't

grown them specifically against tumour antigens. We're just

grabbing a bunch and hoping they're active against the tumour

Some of the T cells will actually trigger an autoimmune reaction,

as autoreactive T cells would normally be kept under anergy. Butsince we've stimulated them in the lab, they are activated, and

ready to cause some havoc

But there are problems with this method:

Polyclonal stimulation

Individualised for the patient

Low toxicity compared to harsh chemo drugs

Advantages

Need to collect cells and pieces of the tumour

Chance of autoimmunity

Very high cost

Not yet proven to be effective

Disadvantages

Cell based therapies

The patient needs their immune system to mount a response (compared to

passive where it just sits back and does nothing)

Active therapies

Take the cells from the person, grow them a bit, and break them open and

inject them back into the patient as a vaccine

Pump the area full of IL-2 to try and overcome anergy

Autologous- from self, hard to get a proper response because it's still

showing self antigen

Allogenic- from someone else, tends to work better because it's recognised

as foreign instead

Don't need to define tumour antigens, just grab a bunch of cells and

mash them up

Individualised against that person's tumours

Advantages

Need to get a piece of tumour, which again requires a biopsy of the

region

Autoimmunity can result, because the tumour cells still display self-

antigen Hard to get a good immune response

Disadvantages

Whole cell vaccines

Take the tumour and a few dendritic cells, get the dendritic cells to display

antigens from the tumour, and put them back into the patient, where the

Dendritic cell vaccines

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Make sure you put in some danger signals as well to help activate the

immune system.

dendritic cell will cause the host's immune system to start attacking the

tumour

Exactly the same advantages and disadvantages as above

Cell free therapies

Active therapy as well

Quite a popular type of vaccine, as it's used for other organisms, like antiviral

vaccines

Sub-unit vaccines

Need a good delivery system and immunogenic substance

Not immunogenic either, because it's just pieces of peptide

It is safe and cheap

But not individualised (hard to find a specific target against the tumour) and we're

not sure if they work.

Attenuated bacteria or viruses (weakened) Virus like particles, which are assembled viruses without the DNA

Biological delivery systems

Emulsions (o/w)

Liposomes (balls of membrane)

Chemical delivery systems

We have some delivery systems

Cytokines

Cytokines reaching the tumour causes signalling within the tumour to

induce apoptosis TNF is one such cytokine

Directly against tumour

IL-2 again is another cytokine which triggers the immune system

Triggers the immune system against the tumour

Immunotherapy either:

Dosing is too frequent

Cytokines have a naturally short half-life as a natural safety mechanism

Tends to be pryogens, cause hypotension and shock etc.

Has systemic toxicity, need to target specifically against the tumour

Immune stimulants

Remember: the environment around a tumour is immunosuppressive Toxins which are used to trigger danger signals to cause an immune reaction

CpG is a bacterial component which binds to the Toll-like receptor of phagocytic

cells (like dendritic cells) to cause a danger signal, and kick start the immune

system in that region

Antibodies

Quite specific against the tumour cells

We can form specific antibodies against tumour targets

They can circulate around the body for months, requiring infusions just a fewtimes a year

They are also great in terms of half-life

Mouse or chimeric antibodies aren't like human ones, they will be attacked

But the antibodies themselves tend to be toxic somewhat due to the immune

reactions they are able to cause

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by the immune system leading to anaphylatic symptoms

They also tend to be bulky, so they get stuck in small capillaries, so they might not

be able to reach the tumour

And they are still really expensive

Targets the HER-2 receptor in many ways:

HER2 is able to become cleaved in the membrane, that can cause signalling.

The cleaving is blocked once herceptin binds

HER2 is able to dimerise with other HER receptors , which activatessignalling. Herceptin prevents dimerisation

Immune cells which are able to detect the presence of herceptin on the cell

will trigger apoptosis of the tumour cell, as it's been coated with this

antibody (remember: antibodies are involved in opsonisation, marking cells

out for the immune system)

The cancer cell will recognise the HER2 receptor is faulty due to this

attached antibody, it will destroy its own HER 2 receptor

Signals for proliferation, mobility (metastasis) and survival

Plus it codes for VEGF, a known angiogenesis agent

Why is blocking signalling so important?

Herceptin- CANCER target

CTLA-4 is sometimes expressed by T cells when communicating to an APC

cell

If CTLA-4 is expressed, then T cell activation is cancelled

So if we blocked CTLA-4, then we would increase the immune system, as it

relieve the inhibition

Anti-CTLA-4 antibodies can lead to autoimmune disease, the patient

needs to discontinue if symptoms of an autoimmune disease appear

Only problem is, CTLA-4 is there for a reason, normally used to prevent

autoimmune diseases

Anti-CTLA-4 IMMUNE system target

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Intro/Glossary

Cure

Removal of all cancerous cells from the body. Ideally, the patient will now have the

same life expectancy as someone who doesn't have cancer.

Remission

Reducing the cancer, even to below detectable levels. However, the cancer is not

completely removed, and may return at any time.

Adjuvant chemotherapy

Additional therapy given with the main method of treatment. For example, adjuvant

chemotherapy is chemotherapy given in addition to surgery (the main treatment).

Adjuvant therapy may also include radiation as well. All this is done to decrease the

chances of reoccurrence of cancer

Neo-adjuvant chemotherapy

Chemotherapy given BEFORE the main treatment, for example, chemotherapy may be

carried out to reduce the size of a tumour before surgery, which can reduce the

amount of tissue to cut, reduce the vasculature (that's a good thing, means you'd lose

less blood during surgery) and make it shrink away from healthy tissue to save that

tissue.

NOTE: Remember, chemo is more effective on the outer edge of solid tumours, which

causes the shrinkage.

Palliative chemotherapy

By this point, we know the cancer can't be cured, so chemo is given to reduce thetumour sizes to relieve symptoms. PLUS it can be used to extend life. Just remember,

we can't cure them by this point, make them more comfortable and live a bit longer.

TMN staging system

T= size of the initial tumour, higher the number, bigger it is

N= number of lymph nodes or extent of spread along lymph nodes, higher the number,

it's spread more throughout the lymphatic system

M= indicates if it has metastasized, where 0 is no, 1 is yes.

e.g. T2N1M0 means it's a medium sized tumour with little regional node infiltration and

no distant metastasis.

Metastasis

Bone (leads to bone pain)

Liver (leads to jaundice)

Brain (leads to mental changes)

Lungs (leads to difficulties in breathing)

Cancer cells are able to split off and travel around the body to for new tumours at

different sites of the body. There are four main sites they will go to, leading to a

common set of symptoms:

Disease templates

Breast cancer

The most common cancer in females. However, it does occur rarely in males. The

disease is also more common in older people, which is common for cancers.

Workshop 1- Solid tumours

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Age

Family history

Race

BRCA1 and BRCA2 double strand DNA repair mechanism genes are faulty in a

high number of cases. This mutation can be passed down, leading to somewomen developing breast cancer quite early in life

Early menarche (menstruating from a young age)

Not having children

Increased exposure to estrogen

Pathophysiology is common to most cancers, where the genetic material of cancerous

cells is damaged, leading to unregulated growth. However, there are some specific risk

factors:

Solid, hard

Irregular

Non-tender

Solitary

90% of the time, a small painless lump can be felt

10% of the time, stabbing or aching pain can occur

Sometimes, it can become tender, and a discharge can be seen

Regular screening is recommended

Mammograms and ultrasounds are used to detect them

Very, very curable if picked up early

Signs and symptoms:

See above for symptoms if the cancer is advanced.

See common treatment goals

Now days a partial removal (breast saving surgery) is recommended

Mastectomy (removal of the breasts)

Note: may be just as effective as mastectomy in some cases

Radiation therapy (instead of surgery)

Non-pharmacological treatments:

Pharmacological treatments (see 'Mechanisms of action' and 'side effects' below for

details):

5-flurouracil

Epirubicin

Cyclophosphamide

Adjuvant therapy with FEC is common:

Notice how the above combo has two drugs which are not specific for any parts

of the cell cycle, and 5-FU is specific for the S-phase. This makes them synergistic

as the treatment will work regardless of what stage the cells are in.

Early stage- focus on cure

Paclitaxel

Taxanes

Therefore, avoid use.

CAUTION: anthracyclines have cumulative cardiotoxicity. In other words, if you

used Epirubicin during adjuvant therapy, you can't use it again or anything else in

that family (like doxorubicin).

Late stage- focus on palliative care

Endocrine therapy only if the cancer carries estrogen receptors

Misc

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Tamoxifen- a estrogen receptor antagonist. Normally, the estrogen

stimulates the growth of the tumour.

Trastuzumab AKA Herceptin is only good for HER-2 positive cancers only

i.e. they don't attack the same targets.

In theory, both could be given at the same time if their cancers expressed both

the HER2 receptor and the estrogen receptor

Long acting formulation + short acting for breakthrough pain

Also give laxatives to prevent constipation

Opioids like morphine are the gold standard

Paracetamol can work

NSAIDs can be useful for bone pain

Bisphosphonate for bone pain

Pain

Ondansetron plus dexamethasone

Lorazepam for anticipatory nausea due to anxiety

Nausea

Non-cancer

Prostate cancer

The most common cancer in males, again it is more common in older people. For

obvious reasons, it cannot occur in females.

Age (old)

Race (African Americans are more affected)

Family history

It has been linked to:

Generally little to no symptoms if locallised

Urgency and dribbling if it's starting to spread (the urethra passes through the

prostate gland, so if it's starting to grow, it will block it, so you can't piss as easily)

Can result in back pain plus other generalised symptoms if advanced

Symptoms are:

Only carry it out if symptoms are present, or if the person has a high risk

PSA assay has a low diagnostic value, some people without cancer have increased

PSA, while people with cancer can have a low PSA

Can confirm cases quite easily and quickly

Digital Rectal Examination (DRE) has good diagnostic value, but people aren't

very keen on having them.

Imaging allows points of interest to be mapped out and biopsied (with a

needle) to check for cancerous cells, helps to grade the cancer.

Transrectal ultrasound

Population wide screening is not implemented, but there are some ways to diagnose

prostate cancer:

Gleason score should be taken, which is where the cancer cells are checked to see if

they form glands (well differentiated cells) or not (undifferentiated cells).

Undifferentiated cells will cause a worse prognosis.

Importantly, we need to know how hormones affect the tumour:

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LH-RH (also known as GnRH or gonadotropin releasing hormone) will stimulate

the pituitary gland to release LH (Lutenizing hormone) and FSH (follicular

stimulating hormone)

LH and FSH will stimulate the testes to release testosterones which will stimulate

the prostate to grow, making the cancer worse

We need to target this pathway for a specific treatment (see below)

Surgery to remove the prostate is well recommended for a complete cure at early

stages (this is the main treatment, and what we're aiming for)

It depends on what side effects the patient prefers

However, radiation is just as effective (external beam therapy, where radiation is

fired at the prostate)

Plus old people are not candidates for this treatment, need to use a

pharmacological treatment

At later stages, surgery to remove the testes (orchidectomy) can be performed

(not very popular though)

Or for some patients, it's better for their life if they just waited and watched the

tumour carefully. This is because these people tend to be old, so it might not be

worth dragging them through treatment to make the rest of their lives miserable.

Non pharmacological treatments:

GnRH agonist, will attempt to over-stimulate the pituitary gland, and cause

the receptors to desensitise to reduce the downstream production of

testosterone

Occurs because at the beginning of treatment, the GnRH receptors

haven't desensitised, so there's a lot of testosterone being produced

downstream

Causes 'tumour flare', which causes an increase in symptoms arising from

the tumour, plus hot flushes, decreased impotence and tender breasts

Goserelin injections- depot of goserelin injected monthly

Non-steroidal testosterone receptor antagonist

Prevents testosterone from binding to the receptor, mainly to counteract

the tumour flare effect

Causes the same side effects as goserelin, but can also cause bone loss

(osteoporosis)

Flutamide tablets- given daily for a short period of time

If non-responsive, need to focus on palliative care and maybe some other

Pharmacological treatments (advanced cancers):

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Surgery is not an option, because it's metastasized

Make sure the chemotherapy agent is compatible with the patient

conventional chemotherapy drugs e.g. vincristine etc.

Colorectal cancer

Very common cancer overall in the population

Age is the main one (again)

Low fibre-high fat diet

Sedentary lifestyle

Hereditary (family history)

Inflammatory bowel conditions (especially Ulcerative colitus, Crohn's disease to a

lesser extent)

Risk factors:

Changes in bowel motions (chronic constipation)

Weight loss

Abdominal pain and cramps

Malaena, tarry stools with blood

Bloating

Signs and symptoms:

Most commonly, a barium enema can be used to check for growths

A colonoscopy may also be used

May be anemic, due to blood loss

A DRE can be used to rule out haemorrhoids as the cause of symptoms

Diagnosis:

Remove the tumour and surrounding tissue to make sure to remove all the

traces of cancer for a total cure

Colostomy will be performed just after the surgery, which is where one

part of the bowel will be open to the outside world to allow food in. Later

on, after the ends have healed, the GI tract is put back together.

Again, surgery is first line treatment for non-metastasized cancers, with adjuvantchemotherapy (FOLFOX)

Adjuvant therapy for local invasion of some tissues

Radiation is more effective for rectal cancers

Radiation is not as effective here

Nutritional support to reverse weight loss

Non-pharmacological treatments:

Not for 'rescue use' as for methotrexate

Instead, it improves the action of 5-FU on thymidylate synthase

Folinic acid

5-Flurouracil

Oxaliplatin

FOLFOX (first line treatment):

Capecitabine (prodrug of 5-FU) if not responsive or at late stage

5-FU

Folilic acid

Topoisomerase inhibitor

SEVERE diarrhoea

Irinotecan (instead of Oxaliplatnin)

FOLFIRI

Pharmacological treatments:

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Good for late stage cancers

Bevacizumab is an antibody which prevents the angiogenesis of metastatic

growths, preventing them from growing

Common treatment goals

Generally speaking, at earlier stages of cancer, the tumour is small, encapsulated (i.e.

cells are completely surrounded and cannot leave) and has not invaded any other

tissues. Therefore, a complete cure is possible if the tumour is cut out, with some

adjuvant chemotherapy to make sure there aren't any cancer cells left.

However, in later stages, palliative care is more important, trying to reduce the sizes of

the tumour and distant metastasis. A multitude of drugs can be given, and surgery is

less important because it wouldnt achieve a cure.

Also, we have to weigh up between treating the cancer and preserving the life quality

of the patient. For example, if the person is old and has advanced cancer, then it might

not be worth giving them chemotherapy because it would severely reduce their life

quality without much of an impact on the li