By The Editorial Board, April 14, 2026 | From: The Wall Street Journal


Food and Drug Administration biologics chief Vinay Prasad is stepping down at the end of this month after torpedoing breakthrough rare disease treatments. The grim reaper can’t leave soon enough, but he’s not leaving without kicking patients with late-stage melanoma on his way out.

The FDA on Friday for the second time rejected a promising melanoma immunotherapy by the biotech firm Replimune. Some 8,500 Americans die every year of melanoma, many of whom could be saved by Replimune’s RP1. But Dr. Prasad and Commissioner Marty Makary have decided that for whatever reason they aren’t worth saving.

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RP1 is an oncolytic virus therapy that turbo-charges the immune response in people resistant to other immunotherapies. A modified herpes virus is injected into tumors, which causes cancer cells to burst and release flares that activate and train the immune system to attack cancer cells throughout the body.

Patients with metastatic melanoma who stop responding to other immunotherapies typically die in less than a year. In Replimune’s trial, tumors shrank in nearly all patients and vanished in one of six. About a third went into remission. FDA staff were so impressed by the results that the agency designated RP1 a “breakthrough therapy” in November 2024 to expedite its review.

As we’ve reported, Dr. Prasad last summer overruled career staff to reject RP1. The agency’s main criticism was that its trial lacked a control arm, though this would be unethical in late-stage patients who failed to improve on other therapies. Oncologists around the world lambasted the FDA.

Melanoma World Society president Axel Hauschild wrote to the FDA that a randomized control study “would be considered as unethical” in his home country of Germany. Drs. Makary and Prasad tried to deflect criticism by blaming the rejection on Richard Pazdur, then head of the FDA oncology center.

To defuse the outcry, the FDA last fall agreed to reconsider the drug. But it now appears this was a perfunctory review intended to give Drs. Prasad and Makary cover for their initial blunder in rejecting the drug. The rejection letter on Friday says the agency chose new staff for the second review “to maintain objectivity and account for potential bias.”

In other words, Dr. Prasad selected a new review panel because the original team supported approval. The reasons the FDA cites in the letter for rejecting the drug reflect Dr. Prasad’s bias and show the outcome of the second review was likely preordained.

Start with the claim that the tumor-shrinking effects of RP1 could not be disentangled from that of another immunotherapy that patients were taking concurrently. But all patients had previously relapsed or failed to respond to other immunotherapies. RP1 is intended to help these refractory patients by boosting their response to other therapies.

Replimune submitted additional data showing that cancer in responding patients advanced after a median 30.6 months when they also got RP1, versus 4.4 months of being treated with other immunotherapies. This shows RP1 caused patient tumors to shrink. The FDA ignored this data.

Next, the FDA quibbles that patients who had every tumor injected had higher remission rates than those who had only some. It says this raises questions about RP1’s efficacy. Huh? This shows the drug works. The FDA also complains some patient tumors were injected more than once, which may have augmented the therapeutic effects. So what?

The letter also bizarrely claims that tumor biopsies—which are done in most cancer trials—could have been the reason that tumors shrank and patients entered remission. If only biopsies had such miraculous effects. The FDA implicitly concedes that the RP1 results are impressive by contriving ridiculous reasons to argue they could be exaggerated.

In a defensive note, the FDA letter says the review team “unanimously” agreed to reject the drug. It also claims Replimune defied FDA advice in March 2021 to run a randomized controlled trial. Yet it omits that the FDA also said it would entertain an accelerated approval based on a single-arm trial if the results were compelling, Replimune chair Philip Astley-Sparke tells us.

The FDA further showed its bad faith by leaking the rejection letter to the press. Usually the FDA gives a company time to prepare a press release and inform staff before posting it on its website. The RP1 rejection letter appeared on social media soon after being sent to the company and before it was posted on the FDA website.

Did the FDA leak the letter to control the press narrative? Mr. Astley-Sparke says the perfunctory second review wasted company time and resources. He doesn’t see a way forward for the company since it will be out of funds in 12 months. It would take several years to run the randomized controlled trial that the FDA is demanding.

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Drs. Makary and Prasad may not care if they kill a company, but what about the patients who will die as a result? The rejection will have a chilling effect on drug development by signaling that the FDA is slamming the door on accelerated approvals and requiring a level of evidence of efficacy that fewer cancer drugs could meet.

Congress ought to haul in Drs. Makary and Prasad for questioning. And President Trump might ask why his choice for FDA Commissioner and the mess with Dr. Prasad have undermined his desire for faster cures.