OCTGT Site visit, September 29, 2005 Research Management, Priorities, and Accomplishments Suzanne Epstein, Ph.D. Associate Director for Research, OCTGT
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
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
Communication within OCTGT • Purpose: • Keep all staff informed as to research expertise available in-house for consultation in relation to regulatory work • Encourage flow of Critical Path ideas among all review scientists
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
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
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.
How We Identify Research Priorities Priorities/ Agenda Center Director/ADR Office Director/ADR Division Director/ Branch Chief Staff Project ideas
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
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).
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)
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.
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.
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
Shift in vector biodistribution Fatal pulmonary edema Smith et al. (2004). Molecular Therapy 9:932 Smith et al. (2004). Gene Therapy 11:431 What happens in animals with liver disease? Cirrhotic rats have a severe pulmonary reaction after i.v. adenovirus vector
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
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.
Goals of NTP Study: Retroviral Vectors • 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: Plasmid Biodistribution • 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.
Cell Therapy Products: Living and Changing Cell Product Safe, effective cell therapy tumor inappropriate differentiation or localization cell death
Critical Path Challenges in Cell Therapy Major issues: controlling growth and differentiation of cells, product characterization, immune rejection • 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
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 genome screening to evaluate interacting genes and identify new predictors of cell survival and product efficacy • Model: eye progenitor cells
Identify Markers Supporting BMP Signaling and Predicting Cell Product Survival • Markers predictive of • cell survival identified • in screen: • Signaling molecules • Transcription factors • Cell cycle regulators • Cell adhesion molecules Normal BMPsignaling Low BMP signaling Apoptosis markers: caspase 3, activated JNK pathway Unpublished
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
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
vs lv lv rv rv Inactivation of Notch2 Results in Loss of Notch2+ Myocardial Cells and Hypoplastic Hearts Model: mice in which Notch2 can be turned on or off in specific tissue Heart Notch2- Wild type Notch2- Wild type Notch2+ cells are blue vs = ventricular septation defect Correct tissue formation requires Notch2 signaling Unpublished
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
Critical Path Challenges in Tissue Engineering Major issues: interactions yielding proper tissue structure and function. Strategies to address them - Projects: • Tissue anatomy and factors controlling joint development • Molecular signals determining liver development
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.
Spatial Patterns of Gene Expression CDMP1/GDF5 Key Finding: Expression of growth factors and the enzymes that activate them overlaps only at anatomic boundaries Unpublished
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
Critical Path Challenges in Xenotransplantation Major issues: transmission of infectious agents between species, immune rejection. • Strategies to address them - Projects: • Porcine endogenous retrovirus (PERV) detection and species tropism • Transplantation immunology - approaches to avoiding rejection
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
Porcine PBMC Release Retrovirus that Can Infect Human Cells Pig Human Wilson, C., et al., J. Virol., 1998. 72(4):3082.
PERV-A PERV-C PERV-A/C Infection of Human Cells Determined by Envelope Portion of PERV-C envelope differing from PERV-A by 9 amino acids greatly reduces infection of human cells Gemeniano, et al, Virology, In Press
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.
Critical Path Challenges in Tumor Vaccines MAJOR ISSUES: Product characterization, including tests for identity, purity, potency; animal models, markers for monitoring and immunogenicity. • Strategies to address them - Projects: • Animal models of targeted intervention. • Markers of tumor growth for monitoring. • Immune response assays (used for potency tests)
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
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
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
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.
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
New Technologies Uses of gene expression microarray and flow cytometry High throughput screening provides detailed information. Can be used for characterization of: • Cellular products • Cell substrates • Patient samples
Quality Assessment of Stem Cells by Gene Expression Profile Microarray Identify markers of stem cell state CD24 GTCM-1 Outcome: CBER/NIH/Industry scientists identified and characterized common “stemness” genes in 6 stem cell lines. Bhattacharya, Blood: 103, 2956-2964, 2004
Quantitative Flow Cytometry: Fluorescence Intensity Standardization Calibration curve Intensity, cell subsets Microbead standards • Use fluorescence standardization to permit longitudinal clinical studies and comparison of data from different labs
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
Reference Materials: Needed to Assure Sensitivity and Comparability of Test Methods Retroviral reference material Adenovirus reference material LTR gag pol env LTR • Available from ATCC. • Used to show RCR assay sensitivity, reduce testing without compromising product safety. External RNA spike-in controls for microarray and RT-PCR ERCC • Available from ATCC. • Allows precise titers: • Viral particle • Infectious titer Outcome: Sensitive, consistent testing facilitates progress, provides savings
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.
Questions for the Committee • Please comment on the contributions OCTGT • research 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.