Drugmaker Merck & Co. said Wednesday that it will advance a new cancer drug into bigger patient tests, after promising findings in an early study against a very aggressive, common type of breast cancer.
Merck said its Keytruda shrank tumors to some extent in one-third of 27 patients evaluated in a study called KEYNOTE-012. All had what's called triple-negative breast cancer that had spread outside the breast, and about 85 percent had worsened after multiple rounds of chemotherapy and other treatments - some five or more treatments.
The drug is in a hot new class of medicines, mostly still experimental, called immuno-oncology drugs. They harness the body's immune system to fight cancer through a mechanism that "uncloaks" a substance called PD-1 on hidden cancer cells so they can be spotted and attacked by key immune cells called T cells.
Merck, based in Kenilworth, New Jersey, said it will start mid-stage patient tests of Keytruda in the first half of 2015. It's received accelerated approval for advanced melanoma, but needs further testing for permanent approval.
The company, the world's fourth-biggest drugmaker by revenue, has now reported positive results in testing of Keytruda in melanoma, triple negative breast cancer and non-small cell lung cancer, head and neck cancer, bladder cancer, stomach cancer and Hodgkin lymphoma. Altogether, Merck is studying Keytruda against 30 different cancer types.
"We've now shown efficacy against seven cancers," Dr. Alise Reicin, Merck's vice president for cancer drug development, said in an interview. "There's tremendous excitement in the oncology community" about Keytruda.
Merck reported the latest results Wednesday at the San Antonio Breast Cancer Symposium.
The patients got infusions of Keytruda, known chemically as pembrolizumab, every two weeks and periodic scans to determine the drug's effects.
While 33 percent had some tumor shrinkage, 19 percent had tumors shrink at least 30 percent. Of those, one had her tumor disappear without relapse, two are still receiving therapy and responding, one is off therapy but was still responding, and one has relapsed. In another seven patients, tumors stopped growing but did not shrink.
Triple-negative breast cancer, the type affecting 15 percent to 20 percent of the roughly 1.7 million new breast cancer patients a year worldwide, doesn't respond to three of the main types of treatment for breast cancer. Those target the hormones estrogen and progesterone and a protein called HER-2, all of which fuel cancer growth.
On Saturday, Merck reported at another medical conference that in a study of patients with the blood cancer Hodgkin lymphoma, who had all failed other treatments and weren't eligible for a transplant, two-thirds responded to Keytruda.