FDA Releases Framework for Assessing Gene Therapies in Anticipation of Future Filings

The FDA Tuesday announced 6 final guidances on gene therapy manufacturing and clinical development of products, as well as a draft guidance regarding gene therapies and orphan drugs.

In its announcement, the FDA said it anticipates many more gene product approvals, saying there are more than 900 investigational new drug (IND) applications for ongoing clinical studies; so far, the FDA has approved 4 gene therapy products, such as Zolgensma, the first approved gene therapy for the treatment of children under age 2 with spinal muscular atrophy, and Luxturn, the first gene therapy for inherited vision loss caused by faulty gene mutations.

The 6 final guidances give product developers the FDA’s recommendations on manufacturing issues, incorporating stakeholder input. The FDA said it wants to advance the gene therapy field while also ensuring that the products meet safety and effectiveness standards. The documents include specific ones for hemophilia,

retinal disorders, and rare diseases. They also include information about manufacturing and testing as well as patient follow-up.

“The growth of innovative research and product development in the field of gene therapy is exciting to us as physicians, scientists and regulators,” said FDA Commissioner Stephen M. Hahn, MD, in a statement. “We understand and appreciate the tremendous impact that gene therapies can have on patients by potentially reversing the debilitating trajectory of diseases. These therapies, once only conceptual, are rapidly becoming a therapeutic reality for an increasing number of patients with a wide range of diseases, including rare genetic disorders and autoimmune diseases.”

The draft guidance, Interpreting Sameness of Gene Therapy Products Under the Orphan Drug Regulations, is currently open for comments. It contains the FDA’s current thinking about the factors that FDA generally intends to consider when determining sameness between gene therapy products for the purposes of obtaining orphan-drug designation and eligibility for orphan-drug exclusivity; it does not address sameness determinations for other types of products.

The agency’s determination will consider the principal molecular structural features of the gene therapy products, which includes transgenes (the transferred gene) and vectors (the vehicle for delivering the transgene to a cell).

The policies could help lead to the development and approval of multiple treatments for patients with rare diseases, the FDA said.

“As the regulators of these novel therapies, we know that the framework we construct for product development and review will set the stage for continued advancement of this cutting-edge field and further enable innovators to safely develop effective therapies for many diseases with unmet medical needs,” said Peter Marks, MD, PhD, director of the FDA’s Center for Biologics Evaluation and Research. “Scientific development in this area is fast-paced, complex, and poses many unique questions during a product review; including how these products work, how to administer them safely, and whether they will continue to achieve a therapeutic effect in the body without causing adverse side effects over a long period of time.”

To that end, the documents address such issues as the complexity that these so-called one-and-done treatments pose for regulators; the FDA said not all of the answers can be provided in the same way that clinical trials do for conventional drugs. “For some gene therapy products, therefore, although they have met the FDA’s standards for approval, we may need to accept some level of uncertainty around questions of the duration of the response at the time of marketing authorization,” the FDA said, adding that postmarket clinical trials will be vital to ensuring that treatments are safe as well as innovative.