FDA Issues New Guidance for Cell and Gene Therapy Development

The US Food and Drug Administration (FDA) has issued new final guidance to help pharmaceutical and biotechnology companies improve the development, manufacturing and quality control of cell and gene therapies (CGTs).

Announced on November 2, 2026, the guidance introduces recommendations for a comprehensive approach to ensuring that these advanced therapies consistently deliver their intended therapeutic effects. The new recommendations focus on product potency, helping manufacturers confirm that every batch of a treatment meets the required standards before it reaches patients.

The guidance, titled Potency Assurance for Cellular and Gene Therapy Products, replaces the FDA’s previous guidance issued in January 2011. It applies to cellular and gene therapy products regulated as biological products under Section 351 of the Public Health Service Act.

Potency is an important part of developing cell and gene therapies. It refers to a product’s ability to produce its intended biological or therapeutic effect. For example, a gene therapy must be capable of delivering the intended genetic material and producing the desired biological response.

Unlike traditional medicines, cell and gene therapies are often complex to manufacture. Their quality can be affected by several factors, including raw materials, manufacturing processes, storage conditions and differences between individual batches.

The FDA’s new guidance recommends that manufacturers develop a science-based and risk-based Potency Assurance Strategy (PAS). Rather than relying only on final product testing, the agency encourages companies to consider potency at every stage of product development and manufacturing.

The recommended strategy covers five main areas: manufacturing process design, manufacturing process controls, raw material controls, in-process testing and potency testing before batch release.

By combining these measures, manufacturers can identify potential problems earlier and reduce the risk of releasing products that may not work as intended.

The guidance also covers how companies should develop and improve potency tests as their products move through clinical development and towards commercialisation. This includes recommendations for early-stage investigational new drug (IND) applications, biologics license applications (BLAs) and continued monitoring after approval.

The FDA has also included specific considerations for different types of advanced therapies. These include viral vector-based gene therapies, patient-specific treatments and products with short shelf lives.

These considerations are particularly important because some cell and gene therapies are manufactured using material collected from individual patients. In such cases, manufacturers must maintain consistent quality while working with complex production processes and limited timeframes.

Karim Mikhail, Director of the FDA’s Center for Biologics Evaluation and Research (CBER), said patients receiving cell and gene therapies often have serious or life-threatening conditions, including cancers and rare diseases. He emphasised the importance of ensuring that these treatments meet appropriate quality standards and perform as intended.

The FDA believes the new guidance will provide manufacturers with a clearer and more predictable regulatory framework. It is also expected to support innovation by helping companies understand how to build potency testing and quality controls into their development programmes.

Importantly, the guidance offers recommendations rather than introducing new legally binding requirements. Manufacturers can use alternative approaches as long as they meet the applicable regulatory requirements.

To help companies understand the recommendations, the FDA’s CBER Office of Therapeutic Products will host a virtual public webinar on December 10, 2026. The session will explain key aspects of the guidance and provide further information on its implementation.

The updated guidance comes as interest in cell and gene therapies continues to grow, with biotechnology companies developing treatments for cancer, genetic disorders, rare diseases and other serious conditions.

As more of these therapies move into clinical trials and commercial development, maintaining consistent product quality will remain a major challenge. The FDA’s updated recommendations aim to address this challenge while supporting the development of safe and effective advanced therapies for patients.