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FDA Finalizes Cell and Gene Therapy Potency Guidance

lite News Desk 2 min read

The U.S. Food and Drug Administration recommends managing potency throughout cell and gene therapy development and commercial production, combining manufacturing controls with testing rather than relying on release assays alone. Its final guidance, issued November 2, 2026, replaces the January 2011 document on potency testing.

Under FDA’s definition, potency concerns whether a product can produce a specified effect, evaluated through suitable laboratory tests or adequately controlled clinical data involving its intended use. The agency recommends a risk-based approach that brings together process design, manufacturing and material controls, tests during production, and assays for releasing lots. The stated purpose is to help ensure that released lots can deliver the intended therapeutic effect.

According to the guidance, its scope covers human cell and gene therapies regulated under section 351 of the Public Health Service Act as biological products. FDA excludes infectious-disease vaccines, bacteriophage and live biotherapeutic products, products for fecal microbiota transplantation, and allergenic products. The agency states that the recommendations are not binding: other approaches are acceptable if they meet applicable statutory and regulatory requirements. It separately identifies requirements for licensed products, including lot-release potency testing.

For licensed therapies, FDA says samples for each lot’s potency testing must be collected after any manufacturing stages capable of affecting potency. An alternative to the specified release method needs authorization from the Center for Biologics Evaluation and Research, which may permit it only if the assurance provided is at least equivalent. The agency also says changes in manufacturing or testing for an approved biologic must be evaluated for their effects on potency in relation to safety or effectiveness.

The guidance addresses products whose shelf lives are too short to complete a potency bioassay before release. FDA says physicochemical testing may support lot release in those circumstances. It recommends beginning bioassays after production and examining the results following release to help check continuing process performance. Whether that follow-up testing is needed, and how often, should depend on risk.

FDA recommends carrying potency assurance from the investigational new drug application stage through approval of a biologics license application and verification after marketing. For investigational therapies, the agency recommends that sponsors develop the strategy further as clinical studies expand. Descriptions submitted in an investigational new drug application should contain information suited to the product’s development phase.

The earlier guidance addressed how to develop potency tests for investigational new drug and biologics license applications. According to that January 2011 document, it neither selected particular types of assays nor established acceptance criteria for releasing products.

* This article is based on publicly available information at the time of writing.

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