Merck's Keytruda fails triple negative breast cancer pivotal study
Months after the FDA sanctioned the approval of Roche’s runner up checkpoint inhibitor Tecentriq in combination with Celgene’s Abraxane for treatment naive patients with triple negative breast cancer, Merck’s keynote PD-1 Keytruda has stumbled in a late-stage trial as the second or third line of defense against the rare, aggressive form of cancer.
Patients in the 622-patient trial were either given the blockbuster treatment or chemotherapy. The main goal of the study — overall survival — was not met, Merck said, adding that details will be disclosed at a later date.
The US drugmaker will continue to test Keytruda monotherapy and in combination with chemotherapy in earlier stages of the difficult-to-treat disease.
About 10-20% of all breast cancers are triple-negative breast cancers (TNBCs), which characteristically has a high recurrence rate within the first five years after diagnosis. In TNBC patients, the growth of the cancer is not fueled by the hormones estrogen and progesterone, or by the HER2 protein, making it hard to treat.
Roche’s Tecentriq combination with Abraxane was the first-ever immunotherapy to get approval in the firstline TNBC setting. The approval was key for the Swiss drugmaker that is third-in-line — behind Bristol-Myers Squibb and Merck — for the checkpoint inhibitor Iron throne. The large drugmaker must get ahead of its rivals in crucial cancer areas if it wants to hold on to its position, as AstraZeneca carves out a niche for its PD-L1 checkpoint Imfinzi in a subset of non-small cell lung cancer patients.
About 70% of breast cancers diagnosed in people with an inherited BRCA mutation, particularly BRCA1, are diagnosed with TNBC. PARP inhibitors such as AstraZeneca’s Lynparza and Pfizer’s Talzenna are already approved for germline BRCA-mutated breast cancer, and are being investigated in combination with checkpoint inhibitors for TNBC.
Meanwhile, antibody drug conjugates are another potential treatment option for TNBC under investigation.