FDA Offers Gene Therapy Advice on Hemophilia, Other Diseases

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By Greg Langlois

The FDA explained the best ways gene therapy developers can get products to treat hemophilia, retinal disorders, and rare diseases approved to go on the market in new draft guidance documents it released July 11.

The agency’s move reinforces its sustained support for the technology, a type of regenerative medicine treatment that involves modifying a person’s genes or introducing new ones to treat, prevent, or possibly cure disease, Alliance for Regenerative Medicine and co-founder and senior policy counsel Michael Werner told Bloomberg Law in an interview.

“It’s another very clear statement from the agency, from the highest levels of the agency, that expresses support for gene therapy,” said Werner, who’s also a partner at Holland & Knight LLP, where he is a co-leader of its health care and life sciences group. “It acknowledges the role that gene therapy technologies can play and will play in the treatment of diseases that many of which currently have no treatment, other than perhaps palliative care.”

Genetic therapy has the potential to treat cancer, viral diseases, inherited disorders, and more.

“Once just a theory, gene therapies are now a therapeutic reality for some patients,” Food and Drug Administration Commissioner Scott Gottlieb said in a statement. “These platforms may have the potential to treat and cure some of our most intractable and vexing diseases.”

Three Therapies Approved

The agency has approved three gene therapy products so far, all within the past year. The first, Novartis AG’s Kymriah, was cleared in August for children and young adults suffering from aggressive acute lymphoblastic leukemia. The agency approved Gilead Sciences Inc.'s Yescarta, which treats patients with non-Hodgkin’s lymphoma who don’t respond to other treatments, in October. In December, Spark Therapeutics Inc. won U.S. approval for Luxturna, designed to address a gene mutation that causes a form of inherited vision loss.

Kymriah and Yescarta were the first CAR-T treatments approved in the U.S. Therapies using CAR-T, or chimeric antigen receptor T-cell, involve extracting immune-system cells from a patient, modifying them to make them capable of attacking cancer cells, and then re-injecting them into the same patient. They are designed to be one-time cancer treatments.

The guidance documents on hemophilia, retinal disorders, and rare diseases are the first disease-specific ones for gene therapy products. Rare diseases are those that affect less than 200,000 in the U.S. About 7,000 rare diseases affect more than 25 million Americans, according to National Institutes of Health statistics the FDA cited.

“There are a lot of gene therapies that are targeting rare diseases, so the fact that they’ve specifically addressed that is also significant,” Werner said.

Werner’s group, a Washington-based advocacy organization representing the international cell and gene therapy sector, wrote a letter to the FDA in March inquiring about the agency’s disease-specific approach. The organization will submit comments on the drafts, a spokesperson said.

Manufacturing, Safety

In addition to the disease-specific ones, the agency issued three separate guidance documents addressing issues in gene therapy manufacturing. They address chemistry, manufacturing and control information needed in gene therapy applications; testing of retroviral vector-based human gene therapy products during manufacture and patient follow-up; and long-term follow-up after gene therapy administration.

"[W]e know that we still have much to learn about how these products work, how to administer them safely, and whether they will continue to work properly in the body without causing adverse side effects over long periods of time,” Gottlieb said in the statement. “In contrast to traditional drug review, some of the more challenging questions when it comes to gene therapy relate to product manufacturing and quality, or questions about the durability of response, which often can’t be fully answered in any reasonably sized pre-market trial.”

It’s also significant that the three manufacturing guidance documents replace the previous ones the agency issued back in 2008 and 2006, Werner said.

“Clearly this field has advanced beyond anyone’s wildest dreams” since those guidance documents were issued, he said. “It’s critical that the agency’s regulatory approach keeps pace with the science and keeps pace with the technology.”

“The agency makes it quite clear that while it’s critical to modernize their regulations and to support this kind of innovation, they do so without changing the gold standard for safety and efficacy that the FDA has had, not just for these technologies but with all biological products,” Werner added. “We want to make sure there’s a pathway to market, but under no circumstances do we want the FDA to lower its standards or anything close to that. We want to make sure products are safe and effective.”

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