FDA GUIDANCE: Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy Investigational New Drug Applications

This guidance, issued by the U.S. Food and Drug Administration's (FDA) Center for Biologics Evaluation and Research (CBER), outlines the Chemistry, Manufacturing, and Control (CMC) information required for a human gene therapy Investigational New Drug Application (IND). The document's primary goal is to ensure the safety, identity, quality, purity, and strength of an investigational product for use in early-stage clinical trials, while establishing a solid foundation for later-phase development.

The guidance is built on the core principles of a phase-appropriate and risk-based approach. This means the level of detail, rigor, and validation for CMC information increases as a product advances from Phase 1 to later-stage trials. For an initial IND, the focus is on safety and scientific soundness rather than the extensive validation required for commercial approval.

The guidance applies to human gene therapy products, including:

• Viral Vectors (e.g., adeno-associated virus (AAV), adenoviral, lentiviral, retroviral)

• Non-viral Components (e.g., plasmids)

• Genetically Modified Cells (both autologous and allogeneic)

Key CMC Information Requirements for an IND

1. Product Description and Manufacturing Process

• Product Description: A complete description of the drug product and its components is necessary. This includes the origin, derivation, and sequence/map of the genetic construct; the vector system used (including packaging/helper components); and details on cell banks (Master and Working Cell Banks) or, for genetically modified cells, the source and collection methods for starting cells. Critical raw and ancillary materials must be described and qualified.

• Manufacturing Process: A detailed narrative of the manufacturing process, typically accompanied by a flow diagram, is required. This must identify critical steps, in-process controls, acceptance criteria, aseptic processing controls, and for cell products, the chain of identity and chain of custody procedures.

2. Product Control Strategy and Specifications A proposed specification—the list of tests, analytical procedures, and acceptance criteria—is required to ensure product quality and consistency. Key components include:

• Identity: Tests to confirm the product's identity, such as gene sequence confirmation, vector serotype, or phenotypic markers.

• Strength (Quantity/Content): The method for measuring the product's dose, for example, vector genomes per mL ($vg/mL$), infectious units, number of cells per dose, and/or cell viability.

• Purity and Impurities: Measurement of impurities that could affect safety or efficacy.

  • Product-Related: Empty viral capsids, aggregates, or improperly modified cells.

  • Process-Related: Residual host cell proteins/DNA, manufacturing reagents, enzymes, or plasmids.

• Potency: A quantitative, biological assay measuring the product's specific ability to effect its intended function. The guidance emphasizes that sponsors must establish and begin developing a relevant biological potency assay early. While an evolving or interim assay may be acceptable in Phase 1, a fully adequate assay is critical for later-phase development and eventual licensure.

• Safety (Adventitious Agents): Critical safety tests are required to ensure the product is safe for human administration. This includes tests for:

  • Sterility (absence of bacteria and fungi)

  • Mycoplasma

  • Bacterial Endotoxins

  • Replication-Competent Virus (RCV): Testing appropriate to the vector platform is critical, such as for replication-competent lentivirus (RCL) or retrovirus (RCR), replication-competent adenovirus (RCA), and replication-competent AAV (rcAAV).

3. Stability Sponsors must provide a stability testing protocol along with any available data to support the quality and stability of the product for the planned duration of the clinical trial. This includes information on storage conditions, container-closure systems, and in-use stability (e.g., post-thaw).

4. Other Key Considerations

• Reference Standards: A plan for the establishment, qualification, and lifecycle management of reference standards used in testing.

• Comparability: A protocol to assess the impact of any changes to the manufacturing process, site, scale, or components throughout the product's development lifecycle.