The FDA exercised "flexibility" in its regulatory approach for the gene therapy approval, according to the director of the FDA’s Center for Biologics Evaluation and Research (CBER) Vinay Prasad, M.D.
The FDA has issued its stamp of approval to a new, cell-based option to treat Wiskott-Aldrich syndrome (WAS), marking the first therapy of its kind for the rare disease and making Italy’s Fondazione Telethon the first nonprofit to usher a gene therapy across the regulatory finish line in the U.S.Branded as Waskyra, the drug is specifically indicated for children 6 months and older, as well as adults who have a mutation in the WAS gene. To be eligible for the ex vivo gene therapy, patients must have no available human leukocyte antigen-matched related stem cell donor and be cleared for hematopoietic stem cell transplantation, the FDA said in its Dec. 9 announcement.“Today’s approval is a transformative milestone for patients with Wiskott-Aldrich syndrome, offering the first FDA-approved gene therapy that uses the patient’s own genetically corrected hematopoietic stem cells to treat the disease,” director of the FDA’s Center for Biologics Evaluation and Research (CBER) Vinay Prasad, M.D., said in a release.The drug was developed through decades of research at the San Raffaele Telethon Institute for Gene Therapy in Milan, Fondazione Telethon said in a press release.The organization, an Italian nonprofit that specializes in rare and complex genetic diseases, is the first nonprofit to have successfully taken an ex vivo gene therapy from the lab to regulatory approval, it added.Waskyra is made up of a patient’s own hematopoietic blood stem cells, which are genetically modified to include functional copies of the WAS gene and reinfused intravenously following chemotherapy. In two open-label studies, as well as an expanded access program that the FDA allowed in Fondazione Telethon’s data package, the rate of severe infections shrank by 93% in the six to 18 months post-treatment period compared to the rate observed in the 12 months before treatment, according to the FDA. Moderate and severe bleeding events were reduced by 60% in the first year following treatment compared to the year before treatment, and “most” patients did not report such bleeding four years post-treatment, according to the FDA.WAS is a severe disease linked to a gene mutation that impacts immune function and platelet count, causing recurring infections, bleeding episodes and eczema while also putting patients at a higher risk of autoimmune diseases and lymphoma.The disease manifests in early childhood and affects almost exclusively males as an X-linked disorder, with Fondazione Telethon estimating a disease prevalence of 1 in 250,000 live male births.Current treatment options largely manage symptoms as the only curative option is a hematopoietic stem cell transplantation, which is only feasible if matched donors are available."The FDA's approval of Waskyra is an extraordinary achievement – not only for Italian research and for Fondazione Telethon, but for the global rare disease community," Fondazione Telethon’s CEO Ilaria Villa said in a statement. "It confirms the value of a patient-centered model that turns research into real treatments, especially where the market fails to act." European regulators signed off on the treatment last month. In Europe, Fondazione Telethon was one of three participants in a pilot program that supports academic and nonprofit organizations developing advanced therapies that can address unmet medical needs. FDA's 'flexible' approachIn approving Waskyra, the FDA “continues to exercise flexibility in the regulatory approach for rare diseases by considering all available data sources” to “facilitate the advancement of life-changing treatments while ensuring scientific requirements are satisfied,” Prasad said.The agency used this regulatory “flexibility” in several ways during the Waskyra review, according to the announcement. On the manufacturing side, the agency allowed the use of relevant manufacturing and quality data in the drug’s application from a “similar” approved product that was considered “adequately representative” of Waskyra.The FDA’s stated flexibility in approving Waskyra could speak to the agency’s evolving approach toward cell and gene therapies.When Prasad was first appointed as CBER head, some market watchers were concerned of his more stringent regulatory mindset and previous criticism of certain accelerated approval pathways. His brief departure from the agency over the summer opened the door for a potential return to regulatory flexibility within rare genetic diseases, Leerink analysts suggested at the time. Upon his return, Prasad seemed to pivot in that direction, recently outlining a new novel regulatory pathway for personalized therapies to treat severe rare genetic diseases.Still, while Prasad and other regulators have voiced support for cutting the red tape around the review of advanced therapies, the agency has also delivered several surprise negative decisions in the cell and gene area, such as a November rejection of the data uniQure planned to use to support its one-time treatment for Huntington’s disease. Oncology CAR-Ts, meanwhile, will face stricter guidelines under Prasad’s new plans, favoring comparator studies.