IO Biotech says cancer vaccine with Merck’s Keytruda outperformed in late-stage study

IO Biotech (NASDAQ:IOBT) announced on Monday that patients with skin tumors who received its lead cancer vaccine candidate, Cylembio, with Merck’s (NYSE:MRK) anti-PD-1 therapy, Keytruda, lived longer without disease worsening in a late-stage pivotal trial.

Shares of Danish biotech added ~57% in the premarket after the announcement before retracing early gains, while Merck (NYSE:MRK) traded flat. Other cancer vaccine developers include Moderna (MRNA) and BioNTech (BNTX).

Based on findings from its IOB-013/KN-D18 trial, IOBT said Cylembio with Keytruda versus Keytruda alone improved progression-free survival, the study’s primary endpoint, in patients with skin cancer melanoma as a first-line option.

While the drug combo clinically improved PFS versus Keytruda, the results narrowly missed statistical significance, the company noted, citing topline data from the open-label trial, which targeted 407 patients with unresectable or metastatic (advanced) melanoma.

Patients well tolerated the combination regimen, with no new safety signals detected. However, 56% of patients receiving Cylembio plus Keytruda experienced adverse events, out of which the most commonly reported issues were the injection site reactions.

IO Biotech (NASDAQ:IOBT) plans to meet with the U.S. FDA this fall and submit the results to discuss the regulatory path forward for Cylembio as part of a future Biologics License Application for advanced melanoma. Additional results from the study are expected at a future medical event.