BMO Capital Markets pointed to FDA leadership, and CBER Director Vinay Prasad in particular, as potential factors in the agency’s decision to issue a complete response letter for Replimmune’s viral treatment RP1 for advanced melanomas. Shares of the company tumbled 75% on Tuesday.
The FDA rejected Replimmune’s engineered viral immunotherapeutic RP1 for advanced melanoma, the company announced Tuesday, seemingly caught off-guard by the complete response letter.
The issue, according to analysts at BMO Capital Markets, could stem from new leadership at the regulator, especially Vinay Prasad at the Center for Biologics Evaluation and Research (CBER).
“We could see what reads as a final hour shake up, associated with a new FDA and head of CBER (Vinay Prasad), drive softness across the broader sector today,” the analysts wrote in an investor’s note Tuesday morning. “Prasad has previously been critical of the approvability of uncontrolled data, and today we see that opinion underscored.”
Replimmune’s stock is down 75% in early Tuesday trading.
The application for RP1 was supported by data from the Phase III IGNYTE trial, which tested RP1 as a monotherapy and in combination with Bristol Myers Squibb’s checkpoint inhibitor Opdivo. The CRL indicated that the FDA did not consider IGNYTE an “adequate and well-controlled clinical investigation,” according to Replimmune’s statement announcing the rejection.
The biologics license application (BLA) for RP1 was accepted with priority review on Jan. 21, just one day into President Donald Trump’s second term in office and while CBER was still under the leadership of Peter Marks, Prasad’s predecessor.
“The issues highlighted in the CRL were not raised by the agency during the mid- and late-cycle reviews,” Replimmune’s CEO Sushil Patel said in the company’s statement. “Additionally, we had also aligned on the design of the confirmatory study.”
The company said it is requesting a follow-up meeting with the FDA and that it expects the request will be granted within 30 days.
RP1, also called vusolimogene oderparepvec, is an engineered, proprietary strain of the herpes simplex virus, which replicates in tumors and induces a heightened immune response. This is a similar mechanism of action to Amgen’s Imlygic, another drug using the herpes simplex virus to destroy melanoma cells. Replimmune is also studying RP1 in non-melanoma skin cancers as well as for patients with skin cancer who have received organ transplants.
