FDA Approves Merck’s Keytruda for Triple-Negative Breast Cancer

FDA recently approved Merck’s anti-PD-1 therapy, Keytruda, for the treatment of patients with high-risk, early-stage triple-negative breast cancer (TNBC) in combination with chemotherapy. 

The agency based its approval on the Phase 3 KEYNOTE-522 trial, which showed that Keytruda in combination with chemotherapy before surgery and continued as a single agent after surgery substantially prolonged event-free survival (EFS) in TNBC patients compared to chemotherapy alone. 

Specifically, researchers found a 37 percent reduction in risk of disease progression that precluded surgery, a local/distant recurrence, a second primary cancer, or death from any cause. 

In total, FDA approved Keytruda for 30 indications in the US. 

“Triple-negative is a difficult-to-treat type of breast cancer that unfortunately is more common in the U.S. in younger women and in Black women,” Vicki Goodman, MD, vice president of clinical research at Merck Research Laboratories, said in the announcement.

“We are proud to offer a new treatment option for patients faced with this challenging cancer. This neoadjuvant and adjuvant combination with KEYTRUDA is the first immunotherapy regimen to be approved in high-risk early-stage TNBC, marking a meaningful milestone for the breast cancer community,” Goodman continued. 

Immune-mediated adverse reactions, severe or fatal, can occur during or after treatment with Keytruda. These adverse reactions include pneumonitis, colitis, hepatitis, nephritis, solid organ transplant rejection, and allogeneic hematopoietic stem cell transplantation complications. 

Keytruda should be withheld or discontinued and corticosteroids administered based on severity of the adverse reaction, a Merck spokesperson explained. 

In November 2020, FDA granted accelerated approval to Keytruda for patients with locally recurrent unresectable or metastatic triple-negative breast cancer. 

The agency based its accelerated approval on KEYNOTE-355, a Phase 3, randomized, placebo-controlled trial in patients with locally recurrent unresectable or metastatic TNBC who were not previously treated with chemotherapy. 

Patients experienced a progression free survival of 9.7 months in the Keytruda plus chemotherapy arm and 5.6 months in the placebo arm. 

TNBC accounts for nearly 10 to 15 percent of all breast cancers. TNBC differs from other types of invasive breast cancer in that it grows and spreads faster, has limited treatment options, and has a worse prognosis. 

“Even when TNBC is diagnosed early, 30-40 [percent] of patients will suffer cancer recurrence after standard neoadjuvant chemotherapy and surgery,” Joyce O’Shaughnessy, MD, chair of breast cancer research at Baylor University Medical Center, said in the recent announcement. 

“There is a high unmet need for new treatment options. Today’s approval is very welcome news and has the potential to change the treatment paradigm by now including an immunotherapy as part of the regimen for patients with high-risk early-stage TNBC,” O’Shaughnessy concluded.