Food and Drug AdministrationCenter for Biologics Evaluation and Research

The Office of Cellular, Tissue, and Gene Therapies Web Seminar Series

presents:

The chemistry, manufacturing and controls (CMC) section of a

gene therapy INDAndrew P. Byrnes, Ph.D.

Chief, Gene Transfer and Immunogenicity BranchDivision of Cellular and Gene Therapies

What are gene therapy products?

• Gene therapy products:– Are administered as nucleic acids, viruses or

genetically-engineered microorganisms, and – Mediate effects via:

• Transcription or translation of transferred genetic material, or

• Integration into the genome

• How are gene therapy products used?– To modify cells directly in patients, or– To modify cells in vitro that are then administered

to patients

Examples of gene therapy products

1. Plasmid expressing an enzyme

2. AAV expressing a coagulation factor

3. T cells modified with a retrovirus to express a novel receptor

4. Bacterium expressing a tumor antigen

5. Oncolytic adenovirus expressing a cytokine

Complexity of a gene therapy manufacturing process

Growth factors

Donor-derived PBMCs CD34+

cells

Retroviral vector

Transduced CD34+ cells

CD34+ selection

Fibronectin coated flask

Before you begin manufacturing…

2008 Guidance for FDA Reviewers and Sponsors: Content and Review of Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy Investigational New Drug Applications (INDs)

Presentation outline• Components used in product

manufacture

• Final product testing and characterization

• Good manufacturing practices (GMPs)

Components used to manufacture the product

• Vector• Cells• Banking system

– Master cell bank (MCB)– Master viral bank (MVB)

• Reagents

Vector• Description, history and details on

derivation of construct

• Vector diagram

• Sequence analysis (from MVB)– Full sequence for vectors <40 kb– Vectors >40 kb: sequence inserts,

flanking regions, modified regions– Description of unexpected sequences

• Raw sequence data is not sufficient

Cells• Cell substrate for production of vector

– History, source, general characteristics

• Cells used as cell therapies – Source

• tissue and cell type– Collection procedure

• mobilization, surgery, leukapheresis, devices used– Donor Eligibility

• infectious disease screening & testing, 21 CFR 1271

MCB and MVB safety testing

• Sterility• Mycoplasma• Adventitious Virus

– In vitro and in vivo adventitious virus assays– Bovine and porcine viruses

• Not needed if reagents tested– For human cell lines:

• Typically EBV, HBV, HCV, CMV, HIV 1&2, HTLV 1 & 2, B19– For murine cell lines:

• Typically mouse antibody production test, retroviruses– Replication-competent virus (for MVB)

Master cell bank characterization

• Identity– Examples:

• Isoenzyme• Karyotype• Short tandem repeat (STR) profiling

• Viability• Stability

Reagents used in manufacturing

• Tabulation of reagents– Final concentration– Vendor– Source (human, bovine, etc.)– Grade

• e.g. licensed product, clinical grade, reagent grade

• May need to provide details on reagent manufacturing

• Certificates of Analysis• Cross reference letters• Qualification program

– Safety testing and quality assessment

Product Manufacturing

• Vector production / purification– Describe all steps

• e.g. cell growth, infection, harvest, purification, formulation, vialing, storage

– Flowchart

• Describe the formulation– Buffer components– Excipients– Product concentration– Storage

Final Product Testing

• Goals:– Safety– Product characterization– Product lot consistency

• List all of your:– Release tests– Test methods– Acceptance criteria (specifications)

Final product testing: safety

• Sterility

• Mycoplasma

• Endotoxin

• Adventitious Virus – In vitro virus– Replication competent virus

Final product testing: characterization

• Final product lot release testing– Concentration– Purity

• e.g. residual cellular DNA, empty viral particles – Identity

• e.g. restriction digest– Activity

• e.g. infectious titer– Potency

• e.g. transgene-specific protein expression– Cell viability (if a cell-based product)

• Stability– Storage– Shipping– Compatibility with delivery devices

Product characterization: why?

• To demonstrate lot-to-lot consistency

• To generate solid clinical data– For pivotal trials, characterization assays will

need to be established with appropriate release limits

• To show comparability after manufacturing changes

Current Good Manufacturing Practices (cGMP)

• Goals:– A product with defined and

reproducible quality– Increased control of the

manufacturing process as clinical trials advance

• 2008 Guidance for Industry: CGMP for Phase 1 Investigational Drugs

cGMPsQuality control

• Quality (QC) Program – QC independent of production unit

– Authority to accept or reject materials, lots, procedures and specifications

– Prevent, detect, and correct deviations and failures

cGMPsQuestions for phase I

• Is the manufacturing process reproducible?

• Do you have appropriate testing at critical steps?

• Is there adequate control of the quality of the raw and source materials?

• Are the records and record keeping systems adequate?

cGMPsExamples for early development

• Procedures to prevent contamination & cross-contamination– Aseptic processing– Facility and equipment cleaning and changeover– Tracking and segregation of patient-specific

products • Methods qualification

– Appropriate method specificity, sensitivity, reproducibility

– Lack of interference• Process qualification of safety related

processes– Removal of potentially dangerous impurities

• For a phase I submission, product safety is the focus of the CMC assessment – Freedom from microbes and adventitious agents– Safety-related characterization – Appropriate GMPs

• Gene therapies and other complex biologics can be a challenge to characterize, and often require unique assays

• Product control and process control should increase with clinical development

Summary

Further information

CBER guidance documents:http://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/default.htm

If the webinar series and referenced websites leave you with unanswered questions:CBEROCTGTRMS@fda.hhs.gov or 301-827-5102