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Merck study results signal blood cancer potential for new type of immunotherapy

For years, Merck & Co. has had an upper hand over its chief cancer drug competitor Bristol Myers Squibb. In March, however, Bristol Myers beat Merck to a notable milestone by winning U.S. approval of a first-of-its-kind cancer immunotherapy.

Merck is now playing catch-up with a similar drug of its own. Merck previously showed its drug, known as favezelimab, holds promise treating a few different solid tumor types. On Thursday, it revealed early clinical trial results that suggest favezelimab could help treat a common type of blood cancer, too.

The data were disclosed in two study abstracts published ahead of presentation at the American Society of Clinical Oncology’s annual meeting next month. In the trial, Merck tested favezelimab alongside its immunotherapy Keytruda in two sets of patients with Hodgkin’s lymphoma who progressed after intial treatment for their cancer. One group had previously received Keytruda or another drug like it, while the other hadn’t.

Among 29 patients in the former group, the Keytruda-favezelimab combination shrank cancer in nine, or 31%, with two achieving what researchers defined as a complete response. Patients went a median of nine months after treatment without their disease progressing and lived a median of 26 months.

While those results are early, exploratory findings from a small trial designed to test safety, Merck believes them to be meaningful. The lymphoma patients in this study group have few treatment options, having already progressed after chemotherapy and immunotherapy.

“We’re particularly excited about [these data] because that’s clearly an unmet need,” said Eric Rubin, Merck’s senior vice president for clinical oncology, in an interview.

In the 30 patients who hadn’t received Keytruda or another similar immunotherapy, 73% of patients responded to treatment, with 23% achieving a complete response, according to the second study abstract.

Rubin characterized the results from this group as “not remarkably different” than what the company has observed in a previous study of Keytruda monotherapy in lymphoma. Still, he noted the responses associated with the drug combination appeared to last longer. Those who received Keytruda and favezelimab went a median of 19 months before their disease progressed, compared with 13 months in those treated with only Keytruda in the previous trial.

That potential benefit, however, appears to come with more side effects. The study found that about 85% of patients in both study groups experienced a treatment-related side effect, more than double what Merck reported in the Keytruda monotherapy trial. The most common side effect reported was suppressed thyroid hormones.

In addition, one patient who received a low dose of favezelimab during an early part of the trial developed a disabling case of autoimmune hepatitis. No other patients in the trial experienced a side effect that was considered serious enough to limit the drug dose.

Merck plans to run a Phase 3 study of the Keytruda-favezelimab combination in lymphoma patients whose disease progressed after immunotherapy. The pharma has also advanced the regimen into a large Phase 3 trial for the most common type of colorectal cancer, a tumor type that drugs like Keytruda have struggled to treat. That trial isn’t expected to read out results for about two years, however.

Favezelimab is a type of treatment known as a LAG-3 inhibitor, which shuts off a protein of the same name that suppresses an immune response to tumors. Scientists see LAG-3 inhibitors as potentially working hand-in-hand with drugs like Keytruda and Bristol Myers’ Opdivo, which block another immunosuppressive protein called PD-1. Bristol Myers’ Opdualag was the first to prove that out, succeeding in a Phase 3 trial in melanoma and winning approval from U.S. regulators in March.

Others aim to follow. Along with Merck, Roche, Regeneron and Novartis are also developing drugs that target LAG-3.