How a Melanoma Drug Got a Third Chance at FDA Approval — and What It Means for the Agency's Independence

On May 29, 2026, Replimune Group announced it would submit its melanoma drug for FDA approval for the third time in 14 months [1]. The company's stock surged. Oncologists expressed cautious optimism. And inside the FDA, a new set of officials — installed after a cascade of resignations and firings — had signaled they would treat the application as "an urgent matter" [2].

The drug, vusolimogene oderparepvec (known as RP1), had been rejected twice. The clinical data had not changed. No new trial results had been generated. What had changed was the leadership of the FDA itself — and the political environment surrounding it.

This is the story of how that happened, and what it means for the future of drug regulation in the United States.

The Drug: What RP1 Is and Why It Matters

RP1 is an oncolytic immunotherapy — an engineered herpes simplex virus (HSV-1) designed to be injected directly into melanoma tumors, where it kills cancer cells and triggers a broader immune response [3]. It is used in combination with Bristol Myers Squibb's nivolumab (Opdivo), a checkpoint inhibitor.

Replimune was founded in 2015 by Philip Astley-Sparke and Robert Coffin, who previously built BioVex Inc. and developed T-VEC (Imlygic), the first oncolytic therapy approved in the U.S. and Europe. Amgen acquired BioVex for up to $1 billion in 2011 [3]. Replimune's current CEO is Sushil Patel, who took the role in April 2024.

The drug received Breakthrough Therapy designation and Priority Review from the FDA — designations reserved for treatments that address serious conditions where preliminary evidence suggests substantial improvement over existing therapies [4].

Approximately 110,000 melanoma cases are diagnosed annually in the United States. While early-stage melanoma has a survival rate above 99%, advanced melanoma — the population RP1 targets — carries a five-year survival rate of roughly 16% [5].

The IGNYTE Trial: Strong Signal, Contested Design

The clinical evidence for RP1 comes from IGNYTE, a Phase 1/2, single-arm, open-label study of 140 patients with advanced melanoma whose disease had progressed after prior anti-PD-1 therapy [6].

Source: Replimune IR / FDA Briefing Documents

Data as of May 29, 2026CSV

The results were striking in context. Among patients who had already failed nivolumab alone — where historical response rates are 6-7% — the combination of RP1 and nivolumab produced an overall response rate (ORR) of 32.9% [6]. The complete response rate was 15%. The median duration of response exceeded 35 months, with 85% of responses ongoing beyond one year [7]. Median overall survival had not been reached at the time of analysis, with a three-year survival rate of 54.8% [7].

Safety data was favorable: grade 3 or higher adverse events occurred in 12.8% of patients [6].

The FDA's objection centered not on the magnitude of the response but on the trial's design. IGNYTE was a single-arm study — it lacked a randomized control group against which RP1's contribution could be measured [8]. Reviewers questioned whether the positive results were attributable to RP1 or to nivolumab, and raised concerns about heterogeneity in the patient population [9].

Oncologists involved in the trial argued that a nivolumab-only control arm would have been ethically unjustifiable, since all enrolled patients had already failed nivolumab monotherapy [10]. Twenty-three oncology researchers issued an open letter defending the data, noting that "real-world patient populations will be, by necessity, heterogeneous" [10].

The First Rejection: July 21, 2025

The FDA issued its first Complete Response Letter (CRL) on July 21, 2025, rejecting the Biologics License Application [11].

The rejection was internally contentious. According to reporting by BioSpace, staff at the Center for Biologics Evaluation and Research (CBER) — the division that had reviewed the application for years — had reached a consensus recommendation favoring approval [11]. Richard Pazdur, Director of the FDA's Oncology Center of Excellence and acting director of the Office of Oncologic Diseases within the Center for Drug Evaluation and Research (CDER), intervened to overrule that consensus [11].

An anonymous FDA official told reporters: "This was Rick Pazdur's doing" [11].

CBER Director Vinay Prasad initially opposed Pazdur's position at a conference in early July but ultimately deferred to his objections [11]. Replimune CEO Sushil Patel noted that "the issues highlighted in the CRL were not raised...during mid- and late-cycle reviews" [4].

The market reaction was severe. Replimune's stock crashed 75-77% on July 22, falling from roughly $18.50 to $4.63, with an additional 30% decline the following Monday [12].

Source: NASDAQ/Market Data

Data as of May 30, 2026CSV

The Second Rejection: April 10, 2026

Replimune resubmitted its application in October 2025. The FDA accepted it with a target action date of April 10, 2026, classifying it as a Class II resubmission [9].

In an unusual move, the FDA replaced the review team that had overseen the application for several years, citing a need "to maintain objectivity and account for potential bias" [9]. This swap is atypical for resubmissions and raised concerns within the company and among outside observers.

The second CRL arrived on schedule. The FDA concluded that the IGNYTE trial was "not considered to be an adequate and well-controlled clinical investigation that provides substantial evidence of effectiveness" [9]. The specific objections focused on study population heterogeneity and attribution uncertainty — essentially the same concerns raised in the first rejection [8].

Replimune's stock fell an additional 64%. The company laid off marketing and manufacturing staff [13].

The Leadership Exodus

What happened next was not a change in clinical evidence but a change in personnel.

Between late 2025 and May 2026, the FDA experienced an extraordinary turnover in its senior ranks:

• Richard Pazdur, the oncology official who had intervened to block RP1, retired weeks after being appointed to a new role in November 2025 [11].
• Vinay Prasad, CBER Director, departed in early May 2026 after a turbulent tenure that included being removed and then reinstated [14].
• Marty Makary, FDA Commissioner, resigned on May 12, 2026 [15].
• Tracy Beth Hoeg, who briefly served as interim CDER chief, was also removed [2].

Their replacements — Kyle Diamantas as Acting Commissioner, Karim Mikhail at CBER, and Michael Davis at CDER — represented a near-complete overhaul of the decision-making chain that had twice rejected RP1 [2].

President Trump characterized Makary's departure by saying: "He's a great doctor, and he was having some difficulty" [15]. NOTUS reported that administration officials had grown frustrated with Makary's inability to "wrangle the bureaucracy and move quickly" [16]. Bloomberg reported FDA insiders warning that one more significant error could jeopardize Makary's position [16].

In a CNBC interview before his resignation, Makary defended the Replimune rejections, calling criticism "corporate spin" and stating: "I stand by the scientists at FDA. On my watch, we have not done corrupt sweetheart deals. What we have done is followed the science" [17].

The Third Submission: What Changed?

Replimune announced its third submission on May 29, 2026, after what CEO Patel described as a "productive discussion" and "collaborative dialogue" with agency officials "towards finding a meaningful path forward" [1].

The FDA's statement was notable: it indicated it would "prioritize its review in recognition of the significant unmet need for patients in the advanced melanoma community" [2]. The agency characterized the resubmission as an "urgent matter" — language not used for the prior two reviews.

No new pivotal trial data was submitted. The Phase 3 IGNYTE-3 trial, which has overall survival as its primary endpoint, is not expected to produce results until 2029 [6].

Source: FDA/Replimune Press Releases

Data as of May 30, 2026CSV

The Question of Political Influence

The sequence of events — two rejections, a leadership purge, and then an invitation to resubmit — has prompted pointed questions about executive branch influence over FDA decisions.

The FDA is not an independent regulatory agency. It is a constituent agency within the Department of Health and Human Services, and the HHS Secretary's authority over it is constitutionally derived from the President [18]. Under the unitary executive theory embraced by the current administration, the President possesses authority to "directly manage all executive agencies, including the FDA," according to analysis from Harvard's Petrie-Flom Center [18].

This means there is no statutory firewall preventing White House officials from communicating with FDA leadership about pending drug applications. Whether such communications occurred in the Replimune case is unknown. No formal documentation of White House-FDA contacts regarding RP1 has surfaced, and any informal communications would not be subject to standard transparency requirements.

HHS Secretary Robert F. Kennedy Jr. distanced himself from the original rejections, telling Congress: "This decision comes out of FDA, and we trust the process there" [19]. However, Kennedy inaccurately described the IGNYTE trial as involving "chemotherapy" when it actually involved immunotherapy, and claimed an initial panel "unanimously voted against" the drug — a characterization oncologists disputed, since CBER staff had initially recommended approval [19].

The Wall Street Journal editorial board published a piece accusing FDA leadership of lying about the drug rejection, specifically challenging statements made by Prasad [20].

The Legal Framework

Seven former FDA Commissioners have co-authored a Health Affairs article arguing the FDA should become an independent federal agency, structurally insulated from political pressure in the way the Federal Reserve or SEC are [21]. But current Supreme Court trends questioning the constitutional viability of independent agency structures make such reform unlikely in the near term [18].

Under the Federal Food, Drug, and Cosmetic Act, the authority to approve or reject drugs is formally delegated to the FDA Commissioner and HHS Secretary. There is no explicit prohibition on the President or White House staff weighing in on individual drug decisions, though doing so would break decades of informal norms [22].

Nature Medicine published analysis arguing that while political officials may legitimately set broad policy priorities, "direct involvement in individual product decisions crosses a line that threatens both scientific integrity and public trust in the regulatory process" [22].

The Industry Response: A New Playbook?

The Replimune case is not isolated. In early 2026, the FDA also reversed course on Ebvallo, a treatment for a rare blood cancer that was initially rejected and then reconsidered after leadership changes [9]. The pattern — rejection under one set of officials, reconsideration under their replacements — has drawn attention from industry analysts and pharmaceutical executives.

STAT News reported in February 2026 that FDA drug reviews have become broadly susceptible to political influence, with lobbyists perceiving that decisions tied to administration priorities receive more favorable treatment [23]. Regulatory affairs plans at pharmaceutical companies now reportedly include "political strategy focused on approaching the White House and top health officials" [23]. One industry source told STAT: "The nature of the relationship is so drastic[ally changing]" [23].

BMO Capital Markets analysts warned that while the RP1 resubmission was positive for Replimune, they "remain cautious as we're uncertain what has actually changed" at the FDA [13]. Capital Alpha analysts characterized the Makary-Prasad era as "the most damaging period in FDA history" [16].

The biotech industry has treated the RP1 decision as a "first indicator" of the FDA's direction under new leadership [24]. CEO Patel's description of "shifting goalposts" resonated across the sector, generating anxiety among drug developers about regulatory predictability [24].

Source: OpenAlex

Data as of Jan 1, 2026CSV

The Steelman Case for Reconsideration

There are legitimate arguments for reconsidering RP1.

The clinical data, while from a single-arm trial, showed response rates nearly five times higher than historical controls in a population with no approved alternatives [6]. Patients who responded sustained those responses for years — 54.8% were alive at three years in a disease with a 16% five-year survival rate [7]. Dr. Anna Pavlick, a melanoma researcher involved in the trial, stated that patients treated with the drug "are still alive today who would otherwise be dead" [10].

The FDA has historically been criticized for excessive conservatism in oncology. The agency's own Breakthrough Therapy designation for RP1 acknowledged that preliminary evidence suggested substantial improvement [4]. And the internal disagreement — with CBER's own review staff recommending approval before being overruled — suggests the rejection was not a straightforward application of consensus science [11].

A contradictory signal came from the FDA's own February 2026 policy shift, when under Makary and Prasad's leadership the agency moved to require only one pivotal trial instead of two Phase 3 trials for some cancer drugs [9]. This created an internal inconsistency: the same leaders who relaxed evidentiary standards for some drugs rejected RP1 for lacking a randomized control in a population where conducting such a trial posed ethical challenges.

The Steelman Case for the Rejections

The counterarguments are also substantial. Single-arm trials, however compelling their topline numbers, cannot definitively establish that a drug works. Without a control group, the 32.9% response rate cannot be conclusively attributed to RP1 rather than to nivolumab or to selection bias in the enrolled population [8].

The FDA's mandate under the Food, Drug, and Cosmetic Act requires "substantial evidence" of effectiveness from "adequate and well-controlled investigations" [8]. The agency twice concluded that IGNYTE did not meet this standard. Defenders of the rejections argue that weakening this standard — even for sympathetic cases — sets a precedent that could allow less effective or even harmful drugs to reach the market in the future.

Makary's defense — "I stand by the scientists at FDA" — reflects a view that the Pazdur intervention, while unusual, was within the agency's legitimate scientific review process [17]. The fact that CBER staff disagreed does not, in this view, make the rejection wrong; it means there was genuine scientific disagreement that was resolved through the established chain of authority.

Financial Fallout and Litigation

Replimune's shareholders have paid a steep price. The stock fell from $18.50 before the first CRL to $2.23 after the second — an 88% decline [12]. A securities class action lawsuit, Jboor v. Replimune Group, Inc., has been filed in the District of Massachusetts, alleging the company misled investors by overstating the likelihood of RP1's approval [25]. Multiple additional law firms have announced investigations [12].

The company's projected market opportunity, if RP1 is eventually approved, would be shaped by the eligible patient population — advanced melanoma patients who have failed anti-PD-1 therapy — and by pricing decisions that have not yet been publicly disclosed. Comparable oncolytic and immunotherapy treatments have been priced at $50,000 to over $100,000 per course of treatment.

What Comes Next

Replimune's third application will be reviewed by an FDA whose senior leadership has been almost entirely replaced since the first two rejections. The underlying clinical evidence remains the same IGNYTE data that was twice found insufficient.

The case raises a question that extends well beyond one drug and one company: Is the FDA's drug approval process governed by consistent scientific standards, or is it subject to the preferences of whoever occupies the relevant offices at the time of review? The answer to that question — which the RP1 saga may help clarify — carries implications for every drug in the FDA's pipeline and every patient waiting for treatment.

A Phase 3 randomized trial, IGNYTE-3, continues to enroll patients with overall survival as its primary endpoint, but results are not expected until 2029 [6]. Whether the FDA will approve RP1 before that data matures — and on what evidentiary basis — will be one of the most closely watched regulatory decisions in years.