Late-stage study failure for Bavarian Nordic's Prostvac sends shares down 50 percent

Shares in Bavarian Nordic slumped up to 50 percent Friday after the company announced that it will halt a Phase III study of the PSA-targeted immunotherapy candidate Prostvac (rilimogene galvacirepvec) in patients with metastatic castration-resistant prostate cancer (mCRPC). The company noted that the independent Data Monitoring Committee for the PROSPECT trial determined that based on a preplanned interim analysis, continuation of the study "is futile."

CEO Paul Chaplin remarked "we are extremely disappointed," adding that "this is certainly not the desired outcome." Chaplin said he does not currently expect the results to affect the company's other cancer projects, "but, of course, we need to see the data from the Prostvac study and we need to…make an assessment and learn lessons from it."

The randomised PROSPECT trial, conducted under a Special Protocol Assessment agreement with the FDA, enrolled 1297 patients. The study's main goal was to test whether Prostvac, with or without the addition of granulocyte macrophage colony-stimulating factor, could prolong overall survival in men with asymptomatic or minimally symptomatic mCRPC, compared with placebo.

Chaplin indicated that Bavarian Nordic has not ruled out combination use for Prostvac, which is being developed with the US National Cancer Institute under a cooperative R&D agreement, adding that the company remains a "firm believer in the combination."

FirstWord reports in this therapy area - KOL Insight Prostate Cancer: Find out how KOLs expect the market to evolve, which pipeline treatments are most promising, and which clinical trials will shape treatment decisions. Learn more.

Commenting on the decision to discontinue the PROSPECT trial, Nordea analysts said "this came as a surprise to us and has a considerable impact on valuation," while analysts at Jefferies suggested the results could raise the risk for other cancer immunotherapies with similarities to Prostvac.

Bavarian Nordic stated in January that the data readout for the trial would be delayed until later this year, and more recently said it expects final data to be available in the fourth quarter. For related analysis, see ViewPoints: KOLs remain positive towards Prostvac, despite readout delay and historical precedent.

Last year, Bavarian Nordic initiated a Phase II trial of Prostvac in combination with Bristol-Myers Squibb's immune checkpoint inhibitor Yervoy (ipilimumab) as a potential neoadjuvant therapy in patients with localised prostate cancer.

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