Posted 01 December 2016
By Michael Mezher
Officials from the US Food and Drug Administration (FDA) are defending its proposed approach to regulating stem cell therapies in response to criticism that doing so would slow access to such treatments.
In an article published in the New England Journal of Medicine on Wednesday, FDA Commissioner Robert Califf, joined by Center for Biologics Evaluation and Research (CBER) Director Peter Marks and CBER Deputy Director Celia Witten, make the case that the hype over such treatments outpaces evidence that they are safe and effective.
The timing of the article also raises questions about new legislative requirements related to regenerative medicines proposed in the 21st Century Cures Act, which overwhelmingly passed in a House vote Wednesday evening. Under the act, FDA would be given the authority to grant accelerated approval for regenerative medicines and would be compelled to update its guidance and regulations for such products, as well as to create a set of standards for them.
"The current excitement over the potential for stem-cell therapy to improve patient outcomes or even cure diseases is understandable...However, to ensure that this emerging field fulfills its promise to patients, we must first understand its risks and benefits and develop therapeutic approaches based on sound science. Without a commitment to the principles of adequate evidence generation that have led to so much medical progress, we may never see stem-cell therapy reach its full potential," they write.
While stem cell therapies have been proven to be safe and effective for some uses, such as bone marrow transplantation for hematopoietic reconstitution, the authors say that many of the uses being promoted today aren't supported by robust clinical evidence.
In September, FDA held a two-day hearing to gather input on its proposed approach to regulating stem cell products. During the hearing the agency heard from dozens of speakers, many of whom argued that more stringent regulation would hurt patient access to stem cell therapies. However, despite numerous case studies and anecdotal accounts of miraculous patient outcomes, FDA says there is little evidence supporting stem cell therapy outside of a few indications.
"The assertion that stem cells are intrinsically able to sense the environment into which they are introduced and address whatever functions require replacement or repair—whether injured knee cartilage or a neurologic deficit—is not based on scientific evidence," the authors write.
Furthermore, the authors warn that stem cell therapies raise a number of safety concerns, even when sourced from a patient's own cells, referring to several cases where patients treated with autologous stem cells experienced severe adverse events, including the development of tumors and blindness.
"Such adverse effects are probably more common than is appreciated, because there is no reporting requirement when these therapies are administered outside clinical investigations," they write.
The authors also argue that requiring clinical trials to demonstrate the safety and effectiveness stem cell therapies would be overly burdensome or impractical.
"There is no scientific reason to believe that demonstration of efficacy for stem-cell products should be any different from that for other biologic products. For treatments that truly provide an impressive benefit to patients, the FDA does not require larger studies than are needed to prove that benefits outweigh risks, and when benefits are dramatic, trials for regulatory approval can be modestly sized."