FDA Approval for Gene Therapy: The BLA, CBER, and RMAT Pathway Explained

A gene therapy product intended for U.S. marketing does not go through the same FDA pathway as a conventional small-molecule drug. It is licensed — not approved in the New Drug Application sense — via a Biologics License Application (BLA), reviewed by the Center for Biologics Evaluation and Research (CBER), not the Center for Drug Evaluation and Research (CDER) that reviews most conventional drugs. Along the way, many gene and cell therapy sponsors also pursue Regenerative Medicine Advanced Therapy (RMAT) designation, an expedited-development pathway created specifically for this product class. This guide covers how these three pieces — the BLA, CBER, and RMAT — fit together, and where to find FDA’s gene-therapy-specific guidance documents.

Why Gene Therapy Follows a Different FDA Pathway Than a Conventional Drug

The FDA’s two core marketing-authorization pathways sit under two different statutes. A conventional drug is approved under a New Drug Application (NDA), authorized by the Federal Food, Drug, and Cosmetic (FD&C) Act. A biological product — which by statutory definition includes gene therapies, cellular therapies, and other products derived from living systems — is licensed under a Biologics License Application (BLA), authorized by the Public Health Service (PHS) Act and defined at 21 CFR 601.2 as a request for permission to introduce a biologic product into interstate commerce. There is no NDA pathway available for a gene therapy product; sponsors file a BLA regardless of whether the product is also, in a colloquial sense, a “drug.”

This distinction is not just administrative vocabulary. It determines which FDA center reviews the submission, which statutory exclusivity provisions apply after licensure (the Biologics Price Competition and Innovation Act framework, rather than Hatch-Waxman), and which FDA guidance library governs the technical content expected in the filing.

CBER Is the Reviewing Center, Not CDER

FDA organizes its human-product review authority by center. CDER reviews drug NDAs and most small-molecule INDs. CBER (Center for Biologics Evaluation and Research) reviews biologics under the PHS Act, including the INDs and BLAs for gene therapy, cellular therapy, and most tissue-based products. (A third center, CDRH, reviews medical devices under a separate premarket pathway and is not typically the reviewing center for a gene therapy product itself, though a companion diagnostic used with one may fall under CDRH.)

In February 2023, CBER restructured its cell and gene therapy review function into the Office of Therapeutic Products (OTP) — a large internal “super office” built specifically to handle the growth in cell and gene therapy submissions. OTP separates gene therapy chemistry-manufacturing-controls (CMC) review from cell-therapy/human-tissue CMC review as distinct offices within CBER, alongside clinical review divisions, so that a gene therapy sponsor’s IND or BLA is routed to reviewers whose expertise matches the product type rather than a generalist biologics team.

For a research administrator coordinating a sponsor-investigator IND or an institutional gene therapy trial, this matters practically: CBER (via OTP), not CDER, is the correct point of contact for pre-IND meetings, INTERACT meetings for early-stage novel constructs, and all subsequent formal meeting requests on a gene therapy program.

The Biologics License Application: What It Actually Requires

A BLA is not the first regulatory filing in a gene therapy program — it is the last. The typical sequence is:

• Pre-IND / INTERACT engagement with CBER to align on the nonclinical package and early clinical design (see CASRAI’s FDA Pre-IND Meeting guide).
• Investigational New Drug (IND) application authorizing human study, followed by the phased clinical program (see Clinical Trial Phases).
• BLA submission, structured per the ICH Common Technical Document (CTD) format, containing the full quality (CMC), nonclinical, and clinical evidence package supporting safety and efficacy.

Once filed, FDA generally has 60 days to make a filing decision (i.e., to accept the BLA for substantive review), and substantive review typically runs roughly 6–10 months from filing, depending on whether standard or priority review timelines apply. Gene therapy BLAs carry manufacturing-specific review burden that a small-molecule NDA does not: vector or cell-product characterization, potency assay validation, and comparability data if the manufacturing process changed during development are all reviewed as part of the CMC section, often the single most resource-intensive part of a gene therapy BLA.

Licensure is frequently not the end of FDA’s oversight. Because integrating vectors and genetically modified cells can have effects that only emerge years after administration, FDA’s guidance on long-term follow-up after gene therapy administration calls for extended post-administration observation — commonly cited as up to 15 years for products using integrating vectors — built into the sponsor’s post-marketing commitments and, frequently, a patient registry.

Regenerative Medicine Advanced Therapy (RMAT) Designation

RMAT is the expedited-development pathway built specifically for this product class. It was created by Section 3033 of the 21st Century Cures Act (2016), which added Section 506(g) to the FD&C Act.

Eligibility criteria — a sponsor’s product must:

• Meet the statutory definition of a “regenerative medicine therapy”: cell therapy, therapeutic tissue engineering product, human cell and tissue product, or certain combination products using any of these. Gene therapies, and genetically modified cells with a durable effect (for example, CAR-T constructs), may also qualify.
• Be intended to treat, modify, reverse, or cure a serious or life-threatening condition; and
• Be supported by preliminary clinical evidence indicating the product has the potential to address an unmet medical need for that condition.

Benefits — RMAT designation confers all the benefits of Fast Track and Breakthrough Therapy designation (early and frequent FDA interaction, eligibility for rolling BLA review, and eligibility for priority review), plus RMAT-specific benefits: early FDA discussion of using a surrogate or intermediate clinical endpoint that could support accelerated approval, and discussion of using alternative approaches to satisfy post-approval requirements — such as patient registries, other observational data sources, or expanded-access protocol data — instead of always requiring a new confirmatory trial.

A sponsor requests RMAT designation with or after IND submission; FDA aims to respond within 60 days of the request. RMAT does not change which application type is filed at licensure — an RMAT-designated program still files a BLA reviewed by CBER; the designation changes how FDA engages with the sponsor during development, not the underlying legal pathway.

How RMAT Relates to Fast Track, Breakthrough Therapy, and Priority Review

These programs are often confused because they overlap rather than replace one another:

• Fast Track and Breakthrough Therapy designations are available to drugs and biologics generally (not just regenerative medicine products) and are the baseline expedited programs RMAT builds on top of.
• RMAT is specific to regenerative medicine therapies (including qualifying gene therapies) and automatically carries Fast Track and Breakthrough Therapy benefits once granted, plus the surrogate-endpoint and post-approval-evidence flexibilities described above.
• Priority Review is a review-timeline designation (an eight-month rather than standard ten- to twelve-month review clock from filing) that a product can become eligible for through RMAT, Breakthrough Therapy, or independently if it meets priority review criteria on its own.
• Accelerated Approval is a separate approval pathway (approval based on a surrogate or intermediate clinical endpoint reasonably likely to predict clinical benefit, with a confirmatory trial required post-approval) that RMAT-designated products are often positioned to pursue, but RMAT designation itself does not guarantee accelerated approval will be granted.

None of these designations substitutes for orphan drug designation, which many gene therapies for rare diseases also hold and which confers separate incentives (market exclusivity, tax credits, fee waivers) — see CASRAI’s Orphan Drug Designation guide for how that pathway works and how it can be layered with RMAT.

FDA’s Gene-Therapy-Specific Guidance Documents

CBER maintains a dedicated library of gene and cell therapy guidance documents (its “Cellular & Gene Therapy Guidances” page), separate from CDER’s general drug-development guidance library. These fall into a few recurring categories relevant to a research administrator planning a gene therapy protocol:

• CMC guidance for INDs and BLAs — e.g., “Chemistry, Manufacturing, and Control (CMC) Information for Human Gene Therapy Investigational New Drug Applications,” first issued January 2020, addressing what manufacturing and testing data FDA expects at the IND stage.
• Long-term follow-up guidance — FDA’s guidance on long-term follow-up after gene therapy administration, which underlies the extended post-marketing observation periods discussed above.
• Disease- or modality-specific guidance — FDA has issued guidance targeted at specific therapeutic areas (for example, human gene therapy for neurodegenerative diseases) and at specific technical questions (for example, interpreting “sameness” of gene therapy products under the orphan drug regulations, and studying multiple versions of a cellular or gene therapy product within a single early-phase trial).
• Genome-editing-specific guidance — as genome-editing constructs (e.g., CRISPR-based products) have matured from early-phase to later-stage development, CBER has issued guidance addressing considerations distinct from earlier-generation gene addition therapies, including safety assessment approaches for genome editing.

Because this is one of the fastest-evolving guidance libraries FDA maintains, sponsors and research administrators should treat any specific document list as a starting point, not a substitute for checking CBER’s guidance page directly before finalizing a submission — draft guidance is frequently issued, revised, and finalized as the science and CBER’s own review experience develop.

What This Means for Institutional Research Administration

For an institution running or hosting a gene therapy trial, the CBER/BLA/RMAT framework touches several administrative functions beyond the regulatory-affairs office itself:

• Institutional Biosafety Committee (IBC) review under the NIH Guidelines for Recombinant/Synthetic Nucleic Acid Molecules runs in parallel with, and is independent of, FDA’s IND/BLA review — both are typically required before a gene therapy protocol can enroll subjects at an NIH-funded institution.
• Informed consent for a gene therapy trial carries some distinct elements (e.g., long-term follow-up commitments, and in some cases the potential for germline or shedding-related risk disclosures) beyond a standard consent template — see CASRAI’s Informed Consent in Research guide.
• Sites should confirm Good Clinical Practice training and documentation expectations under ICH GCP apply in full to gene therapy trials, including the manufacturing chain-of-custody documentation that vector or cell-product handling adds on top of standard investigational-product accountability.

Frequently Asked Questions

Is gene therapy approved or licensed by the FDA?

It is licensed. FDA authorizes a gene therapy product for U.S. marketing through a Biologics License Application (BLA) under the Public Health Service Act, not through a New Drug Application (NDA) under the FD&C Act. The distinction is more than terminology — it determines the reviewing center, the applicable statutory framework, and the post-licensure exclusivity provisions that apply.

What’s the difference between a BLA and an NDA for a gene therapy?

An NDA is the approval mechanism for conventional drugs under the FD&C Act, reviewed by CDER. A BLA is the licensing mechanism for biological products — including all gene therapies — under the PHS Act, reviewed by CBER. Gene therapy sponsors file a BLA; the NDA pathway does not apply to this product class.

Which FDA center reviews gene therapy submissions?

CBER (Center for Biologics Evaluation and Research), specifically through its Office of Therapeutic Products (OTP), established in February 2023 to handle the growth in cell and gene therapy review workload. CDER, which reviews most conventional drug NDAs, is not the reviewing center for gene therapy products.

What is RMAT designation and how is it different from Breakthrough Therapy?

RMAT (Regenerative Medicine Advanced Therapy) designation, created by the 21st Century Cures Act in 2016, is available specifically to qualifying regenerative medicine therapies, including many gene and cell therapies. It automatically includes all Fast Track and Breakthrough Therapy benefits, plus additional benefits specific to regenerative medicine products: early FDA discussion of surrogate/intermediate endpoints that could support accelerated approval, and flexibility on how post-approval confirmatory evidence can be gathered.

Does CRISPR-based gene editing follow the same FDA pathway as other gene therapies?

Yes, at the level of the regulatory pathway itself: a genome-editing product intended for U.S. marketing is still licensed via BLA and reviewed by CBER/OTP, and may still qualify for RMAT designation if it meets the same eligibility criteria as other regenerative medicine therapies. CBER has issued genome-editing-specific guidance addressing technical considerations (such as safety assessment approaches) that differ from earlier-generation gene-addition therapies, but the underlying licensing framework is the same.