Chemo Tops Pfizer, Merck KGaA Drug in Big Stomach Cancer Test

Xconomy New York — 

Pfizer and Merck KGaA’s bid to have a stomach cancer treatment that could leapfrog rival immunotherapies has fallen short.

The companies announced Tuesday that a Phase 3 study testing avelumab (Bavencio) didn’t do better than chemotherapy at extending the lives of patients with gastric cancer. The drug was given to patients whose cancer could not be treated with surgery, and whose disease failed to respond to two earlier treatments. The trial, noted Luciano Rosetti, Merck KGaA’s global head of research and development in a statement, was the first Phase 3 study to ever pit an immunotherapy drug called a checkpoint inhibitor against chemotherapy, not a placebo.

Despite the clinical trial failure, Merck KGaA, based in Germany, and New York-based Pfizer (NYSE: PFE) still have another shot at success. A separate Phase 3 study is already underway testing the drug against chemotherapy in newly diagnosed gastric cancer patients.

Avelumab is an antibody drug that targets a protein produced by tumors called programmed death ligand-1 (PD-L1). The drug is one of several FDA-approved checkpoint inhibitors, drugs that block signals that some cancers use to evade detection by the immune system. Checkpoint inhibitors have been approved for a variety of cancer types, and gastric cancer is among them. In September, Merck’s (NYSE: MRK) pembrolizumab (Keytruda) was approved as treatment for advanced forms of the disease. And earlier this year, Bristol-Myers Squibb (NYSE: BMY) reported positive results from a Phase 3 study testing its immunotherapy nivolumab (Opdivo) in gastric cancer. Both drugs have become huge sellers, bringing in some $5 billion combined in 2016.

Pfizer and Merck KGaA, on the other hand, have been trying to gain ground with avelumab. The two struck up a partnership with in 2014 and the drug notched its first two FDA approvals—for bladder cancer and Merkel cell carcinoma, a rare type of skin cancer—this year. Still, that leaves avelumab well behind its rivals in an increasingly competitive space.

Pfizer and Merck KGaA tried to close the gap by testing its drug against chemotherapy, not a placebo—a more difficult test than pembrolizumab and nivolumab faced in gastric cancer. As a result, Evercore ISI analyst Umer Raffat cautioned against viewing the Pfizer and Merck KGaA drug as inferior to the Bristol and Merck drugs. As a third-line treatment for gastric cancer, chemotherapy generally helps extend peoples’ lives by six months—better than the results shown by either the Bristol and Merck drugs in their respective gastric cancer trials. That means that the Pfizer/Merck KGaA study, which enrolled 371 patients, was a “very high risk trial to begin with,” Raffat wrote, “and the fact that it didn’t work doesn’t necessarily imply that avelumab is worse off on efficacy” versus nivolumab/pembrolizumab.

The companies will provide more specifics on the data at a future, unspecified medical meeting.

Image by Flickr user Double-M via a Creative Commons license.