Merck spotlights promising data on 'breakthrough' cancer immunotherapy MK-3475

Merck ($MRK) highlighted evidence of a rising response rate to its closely watched PD-1 immunotherapy MK-3475, spotlighting an 81% overall survival rate for advanced melanoma patients after 12 months of therapy with 41% of all patients demonstrating tumor shrinkage--rising to an impressive 51% for one group at the high end of the dose range.

About one in 10 patients were ranked as "complete" responders to the therapy, with 88% of all 49 responders showing no signs of disease progression.

The new data offer some additional encouragement for the team handling the Phase Ib trial, which has enrolled more than 1,000 patients--extremely unusual for that stage of development. These checkpoint receptor inhibitors are designed to expose cancer cells to an immune system attack, and initial results indicate that this could offer a major advance in treating cancer.

For Merck, which has experienced a series of pipeline setbacks in the past two years, MK-3475 has emerged as one of its most important programs in the clinic with blockbuster potential. It's already in a Phase III registration study, a head-to-head with Yervoy for advanced melanoma. And there are 8 studies underway with more than 3,000 patients as a dedicated research team stays focused on rapid progress for the therapy, which the FDA has singled out with its breakthrough therapy designation.

ISI's Mark Schoenebaum fired off a quick response to the data, noting that MK-3475's response rate looked increasingly similar to the data that Bristol-Myers Squibb ($BMY) is seeing for a combo melanoma therapy of Yervoy plus its PD-1 drug nivolumab.

"The 12-mo survival data appears to imply that MRK's PD1 by itself is tracking similar to Bristol's PD1+Yervoy combo," writes Schoenebaum. "However, we would note that survival curves will mature as we go out further. Of note, the median OS has not been reached."

Roche ($RHHBY) is also barreling ahead with its own immunotherapy program for a PD-L1 therapy.

- here's the press release

Special Reports: 10 top drugs in biopharma's late-stage pipeline - MK-3475, Merck | Top 10 experimental cancer drugs - 2013