in my clinical practice i use fdg-pet for the following
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In my clinical practice I use FDG-PET for the following
• 1- Staging • 2- Therapeutic monitoring• 3- Staging and therapeutic monitoring• 4- I do not use FDG-PET; no access• 5- I do not use FDG-PET; not cost
effective
“PET scans to image pharmacodynamic effects of vemurafenib”
Grant McArthur MB BS PhDPeter MacCallum Cancer Centre
Melbourne, Australia
Disclosure Information
• I have the following financial relationships to disclose–Research support from: Pfizer,
Millennium & Novartis
Talk Outline
• FDG-PET response as a clinical tool in oncogene addiction – lessons from gastrointestinal stromal tumors (GIST).
• Responses on FDG-PET in patients treated with the BRAF inhibitor vemurafenib. Clinical and biological implications.
• FDG-PET as an early marker of response in patients with rare BRAF mutations.
• Could inhibition of glucose metabolism be important in response to BRAF inhibitors?
Oncogene Addiction
GISTCML
Mut EGFR APML
p210Bcr-Abl
FDG-PET to assess response- Re-Evaluating the Conventional Treatment Paradigm
GIST Before Imatinib 24 hours after starting Imatinib
The Limitations of Structural Imaging
6 months after commencing imatinib
Monitoring response to imatinib in GIST
Survival
Adapted from Stroobants et al, EJC, 2003
Time (Days)
PET respondersn=13
PET non-respondersn=8
0 100 200 300 400 500 600 700
0.00.10.20.30.40.50.60.70.80.91.0
p=0.001
Talk Outline
• FDG-PET response as a clinical tool in oncogene addiction – lessons from gastrointestinal stromal tumors (GIST).
• Responses on FDG-PET in patients treated with the BRAF inhibitor vemurafenib. Clinical and biological implications.
• FDG-PET as an early marker of response in patients with rare BRAF mutations.
• Could inhibition of glucose metabolism be important in response to BRAF inhibitors
Vemurafenib: a novel, small molecule inhibitor Selectivity for BRAFV600E in vitro and in vivo
Phospho-ERK IC50 (nM)
A375COLO829COLO205
SW620SKMEL2
201030
>40,000 14,000
Selective in cellular assays
V600E
WT
Selective for BRAFV600E kinaseamong 70 kinases screened
10–100
IC50 (nM)
100–10001000–10000
Kinase domain binding
Bollag et al , Nature, 2010
BRAF
Bollag et al , Nature, 2010
Dose dependent regression of V600E tumors
CT Response- Phase 1 PLX06/02 Study
Flaherty et al, NEJM. 2010Flaherty et al, NEJM, 2010
1009080706050403020100
Prog
ress
ion-
free
sur
viva
l (%
)
No. of patients in follow upDacarbazineVemurafenib
0 1 2 3 4 5 6 7 8 9 10 11 12
Hazard Ratio 0.26 (95% CI; 0.20 - 0.33)Log-rank P<0.0001
Months274275
213268
85211
48122
28105
1650
1035
616
34
03
Dacarbazine (N=274)
Vemurafenib (N=275)
Progression-free survival (30 Dec 2010, final pre-planned analysis at IA)
Median 1.6 mos Median 5.3 mos
McArthur et al, ESMO, 2011
Heterogeneity of ERK phosphorylation at progression
• Recovery of ERK and MEK phosphorylation at disease progression was observed in some but not all patients
300
250
200
150
100
50
0
H-S
core
Baseline Day 15 PD
pERK1/2 cytoplasmic H-Score300
250
200
150
100
50
0H
-Sco
reBaseline Day 15 PD
pMEK1/2 cytoplasmic H-Score
McArthur ASCO, 2011
Patterns of Progression
Baseline
Response
Progression
Design of Clinical Study
Day 1
VemurafenibScreening
ProcedureFDG-PET
CT
15
FDG-PET
-21 29 57
CT CT
FDG-PET ResponseBaseline
Day 15
Kim, MD Anderson
FDG-PET Response
McArthur….Hicks, J Clin Oncol, 2012
Response Assessment-quantitative analyses
PLX4032 ≥320mg bid (n=27)
Controls (n=4) p
Mean±SD Mean±SD
Drug Exposure day 15 µM.hr
1683±153 69±16 0.0007
Change Target Lesions SUVmax (%)
80±17 8±19 <0.0001
Change Whole Body Lesions % Injected
Dose(%)
84±15 1±41 <0.0001
Metabolic Disease Volume ml (range)
816±423 (7-6945)
597±1012 (16-2113)
Response Assessment-summary
PLX4032 ≥320mg bid (n=27)
Controls (n=4)
Overall Assessment of FDG-response (N, %)
Complete Metabolic Response
3 (11%) 0
Partial Metabolic Response
41(89%) 1
No Response 0 3
Overall Assessment of response RECIST (N, %)
CR 2 (7%) 0
PR 21(78%) 0
SD 3 (11%) 0
100% of patients with BRAF V600E melanoma achieved an FDG-PET response
An example of precision medicine
McArthur….Hicks, J Clin Oncol, 2012
Homogeneity of Molecular Response
A
B
McArthur….Hicks, J Clin Oncol, 2012
Conclusions• FDG-PET is a useful marker of early biological
response to a vemurafenib with 100% of patients achieving partial or complete metabolic response.
• FDG-PET responses were obtained in patients with high volumes of disease.
Conclusions• Limited heterogeneity in FDG-PET response
was found between lesions in individual pts suggesting minimal intrapatient molecular heterogeneity.
• In this small patient cohort, very early FDG-PET response does not appear to be correlated with conventional clinical endpoints of PFS, Best Overall Response by RECIST, time to PR, or Duration of Response.
Talk Outline
• FDG-PET response as a clinical tool in oncogene addiction – lessons from gastrointestinal stromal tumors (GIST).
• Responses on FDG-PET in patients treated with the BRAF inhibitor vemurafenib. Clinical and biological implications.
• FDG-PET as an early marker of response in patients with rare BRAF mutations.
• Could inhibition of glucose metabolism be important in response to BRAF inhibitors?
BRAF K601E treated with the MEK-inhibitor trametinib
A
B
Day 17
K601E represents 1-2% of all BRAF mutations in melanoma
Day 0
BRAF T599 ins I V601 treated with the vemurafenib
A
B
Day 0
Day 18
BRAF L597R treated with the vemurafenib
A
B
Day 0
Day 14
Talk Outline
• FDG-PET response as a clinical tool in oncogene addiction – lessons from gastrointestinal stromal tumors (GIST).
• Responses on FDG-PET in patients treated with the BRAF inhibitor vemurafenib. Clinical and biological implications.
• FDG-PET as an early marker of response in patients with rare BRAF mutations.
• Could inhibition of glucose metabolism be important in response to BRAF inhibitors?
Baseline
Day 15
Kim, MD Anderson
Could inhibition of glucose metabolism be a driver of response?
A
B
Day 0
Day 15
McArthur….Hicks, J Clin Oncol, 2012
Could inhibition of glucose metabolism be a driver of response?
Conclusions
• Mechanistic preclinical studies and correlations with reactivation of the MEK/ERK pathway suggest FDG-PET is pharmacodynamic marker activity of MEK/ERK.
• Inhibition of glycolytic metabolism with siRNAs phenocopies the effects of vemurafenib on cell viability, suggesting inhibition of glycolytic metabolism maybe one component of the anti-tumor activity of BRAF inhibitors
AcknowledgementsKeith FlahertyAntoni RibasPaul ChapmanKeith NolopJeff SosmanKevin Kim
Igor PuzanovJoe GrippoRichard LeeGideon Bollag
Tiffany ParmenterRod Hicks
Jason CallahanFergal KelleherAlex DobrovicCliff Meldrum
PET-imaging colleaguesStudy
CoordinatorsPatients & their
families
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