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Research Management, Priorities,and Accomplishments

OCTGT Site visit, September 29, 2005

Suzanne Epstein, Ph.D.Associate Director for Research, OCTGT

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The Challenge

OCTGT formed to regulate cell therapies, gene therapies, tissues, other novel products

Key issues include:• Vector safety, efficacy• Survival and function of cellular products• Immune responses: efficacy of tumor

vaccines, barrier to therapies• Characterization of complex products

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Roadmap of this presentation

Research management• Communication tools• Identifying research priorities• Assessment tools• Management of resources

Research, selected accomplishments related to:• Gene therapy • Cell therapy• Tissue engineering• Xenotransplantation• Tumor vaccines• New technologies

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Communication within OCTGT

Purpose:

Keep all staff informed as to research expertiseavailable in-house for consultation in relation to regulatory work

Encourage flow of Critical Path ideas among all review scientists

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Tools for Communication within OCTGT

Research work-in-progress seminars

Short research vignettes at staff meetings

Brief abstracts of research programs circulated to staff

Web-based, searchable research annual reports

Dialogue of research managers with leaders of all review divisions

Discussions initiated by review scientists

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Communication Beyond OCTGT

Briefings of Center and Agency leadership, Grand Rounds

Information exchange with stakeholders: 

• Scientific conferences• Publications• Advisory Committee meetings• October 2004 Critical Path Workshop, FDA

Science Forum, this site visit

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How OCTGT Identifies Research Priorities

Receive input about new products on the horizon from pre-submission inquiries, conferences, literature

Identify anticipated areas of major product activity, and Critical Path issues

Monitor for gaps and weaknesses in expertise or redundancies, and address them

Example: A few years ago, we identified the need for adenovirus expertise and recruited an adenovirus research expert to fill the gap.

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How We Identify Research Priorities

Center Director/ADR

Office Director/ADR

Division Director/Branch Chief

Staff Project ideas

Priorities/Agenda

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OCTGT Future Research Priorities Identified

Expertise identified as needed for future product review:

Tissue engineering: partnering/leveraging, adapting by existing staff

Cancer biology models for surrogate endpoints:Build on existing programs

Bioinformatics: enhance/leverage FDA capabilities, collaborate outside FDA

Proteomics: recruitment

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Assessment Tools for Research Productivity

Quantitative metric for peer-reviewed publications, uses impact factors and authorship weighting (limitations of impact scores vs. quality, relevance).

Investigators describe the contributions of their research to Agency mission and other outputs (policy, guidance, advisory committee meetings).

 

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Management of Resources: Outside Funding

Eligible for limited set of grant resources

Grant application prescreening: reviewed for conflicts of interest, alignment with OCTGT mission, possible recusals

Tracking of outside funds

Other leveraging (collaborations and partnering with other FDA centers, other government agencies, academic institutions)

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OCTGT Research Strategies

Anticipate needs, as well as addressing current problems:

Stay ahead of the curve as products and technologies change

Perform studies relevant to entire product classes, not only individual products

Make results public, and thus accessible to all sponsors, to advance the entire field

Some OCTGT research uses current product systems, some of it addresses underlying issues we must understand to move products forward.

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Critical Path Challenges in Gene Therapy

Major issues: vector safety and characteristics,patient immune responses.

Strategies to address them - Projects:

Adenoviral vector safety and biodistribution.

Retroviral vector safety and detection.

Herpesvirus vector safety and characterization.

Host immune responses induced by viral and plasmid vectors.

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Adenovirus Vector Gene Therapy

Public Health Issues and Regulatory Challenges:

Adenovirus vectors being tested in many clinical trials

They efficiently deliver transgenes to the liver

Toxicity has been seen, leading to the death of one patient

Animal models are needed for predicting adverse events and understanding their mechanisms

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What happens in animals with liver disease?

Cirrhotic rats have a severe pulmonary reactionafter i.v. adenovirus vector

Fatal pulmonary edema

Smith et al. (2004). Molecular Therapy 9:932

liver lung spleen kidney heart bone

Vec

tor D

NA

(cop

ies

per

g)

2x107

4x107

6x107

8x107

0.0

1.0x108

marrow

controlcirrhotic

Shift in vector biodistribution

Smith et al. (2004). Gene Therapy 11:431

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Adenovirus Vector Gene Therapy

Outcomes:

Insight into how adenovirus vectors cause toxicity

Animal model for gene therapy in the context of pre-existing liver disease – influence on clinical trial design

Model can be used for safety testing of new vectors

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National Toxicology Program

NTP is administered by NIEHS, federally funded.

Goal: Evaluate the safety of regulated products products nominated by FDA Centers

In 2004, CBER proposed studies of toxicity and pharmacokinetics of gene therapy vectors – the first NTP study of complex biologicals.

Collaborations of FDA, NIH and academic investigators to do large-scale, long term studies.

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Establish a preclinical model for assessing risk of retroviral vector-mediated insertional tumorigenesis.

Assess the effect of vector dose, of deleting the viral enhancer, of using an insulator element

Compare risk of using enhancer-deleted lentivirus vectors

Goals of NTP Study: Retroviral Vectors

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Establish a method for quantitative assessment of vector biodistribution.

Assess the effects of route of administration and of formulation on gene expression, DNA persistence.

Provide baseline information bridging to other vectors and formulations.

Goals of NTP Study: Plasmid Biodistribution

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Cell Therapy Products: Living and Changing

Safe, effectivecell therapy

Cell Product

inappropriatedifferentiation orlocalization

cell death

tumor

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Critical Path Challenges in Cell Therapy

Strategies to address them - Projects:

Key signaling pathways determining cell fate, cell death, and development of anatomic structures

Cell-cell interactions controlling differentiation of cells derived from bone marrow precursors

Immune cell activation and immune responses to cellular therapy products

Major issues: controlling growth and differentiation of cells, product characterization, immune rejection

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Cell Therapy: Interacting Signals That Promote Product Efficacy

Public Health Issue:

For many cell products, only a small fraction survive after administration to the patient. Thus, cell survival is a Critical Path efficacy question

Experimental approach: High throughput whole genomescreening to evaluate interacting genes and identifynew predictors of cell survival and product efficacy

Model: eye progenitor cells

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Identify Markers Supporting BMP Signaling and Predicting Cell Product Survival

Apoptosis markers: caspase 3, activated JNK pathway

Normal BMP signaling Low BMP signaling

Markers predictive of cell survival identified in screen:

•Signaling molecules

•Transcription factors

•Cell cycle regulators

•Cell adhesion molecules

Unpublished

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Cell Therapy: Interacting Signals That Promote Product Efficacy

Outcomes:

Identification of biomarkers that predict survival of cell therapy products, and can serve as manufacturing process controls

• Functional biological interactions, providing link to clinical outcomes

Suggests approaches for improving survival of cellular products following administration to the patient

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Cell Therapy: Requirements for Product Efficacy

Public Health Issues and Regulatory Challenges:

Cellular products being developed for treatment of myocardial infarction, neurodegenerative diseases other diseases.

Once potential biomarker identified, explore its role in vivo to permit characterization tests predictive of product efficacy and safety

A highly conserved signaling pathway which is crucial during development and reactivated during repair of injury requires Notch2

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Notch2+ cells are blue

Inactivation of Notch2 Results in Loss of Notch2+ Myocardial Cells and Hypoplastic Hearts

vs = ventricular septation defect

Notch2-Wild type

rv lvrv

lvvs

Notch2-

Heart

Wild type

Model: mice in which Notch2 can be turned on or off in specific tissue

Correct tissue formation requires Notch2 signaling

Unpublished

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Cell Therapy: Requirements for Product Efficacy

Outcomes:

Identification of markers on cellular products that predict their function and efficacy in vivo

Markers for process controls to characterize cellular products made from different precursors or under different culture conditions

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Critical Path Challenges in Tissue Engineering

Strategies to address them - Projects:

Tissue anatomy and factors controlling joint development

Molecular signals determining liver development

Major issues: interactions yielding proper tissue structure and function.

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Tissue Engineering: Joint Development – Repair

Public Health Issues and Regulatory Challenges:

Joint damage is common, and inadequately treated

Products for repair of joint surfaces have given mixed results. Need to identify factors influencing successful joint formation.

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Spatial Patterns of Gene Expression

Key Finding:Key Finding:Expression of growth factors and the enzymes that activate them overlaps only at anatomic boundaries

CDMP1/GDF5

Unpublished

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Tissue Engineering: Joint Development – Repair

Outcomes:

Identified novel molecular mechanisms contributing to development of the joints.

Micro-environment in vivo influences how cells differentiate and tissues develop.

Related future work relevant also to cell therapies:

Phosphoproteomic profiling of chondrocytes to refine cell product characterization

Correlation of molecular markers with in vivo outcomes to identify sound potency assays

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Critical Path Challenges in Xenotransplantation

Strategies to address them - Projects:

Porcine endogenous retrovirus (PERV) detectionand species tropism

Transplantation immunology - approaches toavoiding rejection

Major issues: transmission of infectious agents between species, immune rejection.

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Xenotransplantation:Porcine Endogenous Retrovirus (PERV)

Public Health Issues and Regulatory Challenges:

Many more patients waiting for transplants than there are organs available

Risk of cross-species transmission of infectious agents, especially in immune-suppressed patients

Some PERV’s can infect human cells

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Porcine PBMC Release Retrovirus that Can Infect Human Cells

0

5000

10000

15000

20000

25000

30000

35000

40000

9 13 20 24 28 31 34 42 52 55

days post-exposure

cpm

inco

rpo

rate

d ST

ST+PBMCI

ST+PMBC

293

293+pbmc

293+PBMCI

Wilson, C., et al., J. Virol., 1998. 72(4):3082.

Pig

Human

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Infection of Human Cells Determined by Envelope

Portion of PERV-C envelopediffering from PERV-A by9 amino acids greatly reducesinfection of human cells

Gemeniano, et al, Virology, In Press

1

10

100

1000

ST (Pig) 293(Human)

Infe

ctio

us

Un

its/

ml

PERV-A

PERV-C

PERV-A/CPERV-A

PERV-C

PERV-A/C

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Xenotransplantation: Porcine Endogenous Retrovirus

Outcomes:

Product Testing: Technical and scientific advice concerning assays for detection of PERV.

Product safety: Determinants of human tropism may reveal mechanisms to block infection and reduce risk of PERV transmission to recipients.

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Critical Path Challenges in Tumor Vaccines

Strategies to address them - Projects:

Animal models of targeted intervention.

Markers of tumor growth for monitoring.

Immune response assays (used for potency tests)

MAJOR ISSUES: Product characterization, including tests for identity, purity, potency; animal models, markers for monitoring and immunogenicity.

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Tumor Vaccines

Public Health Impact and Regulatory Challenge:

More than 1.2 million Americans are diagnosed with cancer and half of them die each year

No tumor vaccine is currently available for general clinical use, but many are under development for cancer therapy

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Identification of Interleukin-13 Receptor 2 as Tumor-Associated Biomarker

Overexpressed in variety of human tumors, compared to normal tissues

Expression of receptor in astrocytoma

Overexpression sensitizes tumor cells to killing by receptor-targeted agents

Extracellular domain of receptor is cleaved and secreted into serum

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Soluble IL-13 Receptor 2 as a Serum Biomarker

Mouse model of metastatic ovarian cancer

Level of soluble receptor increased with tumor growth

Treatment with receptor targeted toxin decreases tumor burden as well as serum level of soluble receptor in mice

Survival improved

Unpublished

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Tumor-Associated Biomarkers

Outcomes:

Cell surface receptor expression as a marker of identity for tumor vaccines

Serum biomarker as a candidate for monitoring.

Animal models for study of interventions.

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Critical Path Challenges: New Technologies

MAJOR ISSUES: Complex products require state-of-the-art analytical methods.

Gene expression microarray

Quantitative flow cytometry

Transgenic animal production

Proteomics

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New Technologies

Uses of gene expression microarray and flow cytometry

High throughput screening providesdetailed information. Can be used forcharacterization of:

Cellular products

Cell substrates

Patient samples

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Quality Assessment of Stem Cells by Gene Expression Profile Microarray

Identify markers of stem cell state

Outcome: CBER/NIH/Industry scientists identified and characterized common “stemness” genes in 6 stem cell lines. Bhattacharya, Blood: 103, 2956-2964, 2004

CD24

GTCM-1

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Quantitative Flow Cytometry: Fluorescence Intensity Standardization

Calibration curve

Microbead standards

Intensity, cell subsets

Use fluorescence standardization to permit longitudinal clinical studies and comparison of data from different labs

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Fluorescence Technology for the 21st Century

Flow Cytometry and Microarrays Need Standards Federal Standardization Initiative: NIST – FDA – CDC Standard Fluorescein Solution Developed Standard Microbeads Developed

NIST Microbead Standard

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Reference Materials: Needed to Assure Sensitivity and Comparability of Test Methods

Available from ATCC.

Used to show RCR assay sensitivity, reduce testing without compromising product safety.

External RNA spike-in controls for microarray and RT-PCRERCC

Available from ATCC.

Allows precise titers:• Viral particle• Infectious titer

Retroviral reference material Adenovirus reference material

LTR gag pol env LTR

Outcome: Sensitive, consistent testing facilitates progress, provides savings

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Summary: Research Prioritizationas an Ongoing Process

New product classes present novel scientific and regulatory challenges and opportunities

We identify scientific questions of regulatory importance and address them.

Solutions to key problems facilitate product

development, inform regulatory decisions and policy.

We welcome questions and comments from the Committee.

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Questions for the Committee

1. Please comment on the contributions OCTGTresearch makes to the Critical Path development of biologics product and their availability.

 2. Please recommend opportunities for research

expansion and redirection, and new collaborations or leveraging.

 3. Suggest research management strategies for

anticipating future biological products and related scientific and product issues.

 4. Provide recommendations for attracting and retaining

high quality scientific staff.