Updated February 1st, 2022

‘It’s A Game Changer’: FDA Approves Keytruda, Chemo Combo To Treat Aggressive Triple-Negative Breast Cancer

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The U.S. Food and Drug Administration (FDA) on Tuesday approved the immunotherapy drug pembrolizumab for the treatment of early-stage triple-negative breast cancer (TNBC), one of the most aggressive and most difficult-to-treat types of breast cancer. Pembrolizumab (Keytruda) is already used to treat other cancers, including melanoma and non-small cell lung cancer.

TNBC accounts for between 10 and 20 percent of all breast cancers. Because TNBC is not sustained by the hormones estrogen and progesterone or by the HER2 protein, it cannot be treated with traditional hormonal therapy or medicines that target HER2 receptors. And because there have been fewer treatment options for TNBC, the FDA's approval of pembrolizumab is seen as a potentially paradigm-shifting advancement in breast cancer treatment.

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For patients with stage 2 or 3 TNBC, adding the immune-boosting medication pembrolizumab to combination chemotherapy before surgery, increases chances of living free of breast cancer, explains oncologist Dr. Sylvia Adams, director of the Breast Cancer Center at NYU Langone's Perlmutter Cancer Center. She was one of several researchers involved with the pembrolizumab trials. "It changes the standard of care and should be discussed with all patients who are diagnosed with stage 2-3 TNBC," she adds. "Yes, it's a game-changer, though there is much more to be learned."

In the phase III trial that preceded the FDA's approval, a regimen of pembrolizumab with neoadjuvant (before surgery) platinum-based chemotherapy and then pembrolizumab alone extended event-free survival in patients with early-stage TNBC. The trial included 1,174, with 784 receiving 200 mg of pembrolizumab every three weeks in addition to neoadjuvant chemotherapyfour cycles of paclitaxel and carboplatin and then four cycles of doxorubicin or epirubicin plus cyclophosphamide. The other 390 study participants received chemotherapy plus placebo.

At the median follow-up of 39 months, pembrolizumab showed a significant event-free survival benefit compared with chemotherapy alone. All patients underwent surgery and received radiation therapy as indicated. Adjuvant treatment (after surgery) included up to nine cycles of pembrolizumab or placebo, depending on which randomized group the patient belonged. The number of cycles varied depending on factors such as disease recurrence or unacceptable toxicity. Pembrolizumab is an anti-PD-1 monoclonal antibody administered intravenously.

"We are proud to offer a new treatment option for patients faced with this challenging cancer," Dr. Vicki Goodman, vice president of clinical research at Merck Research Laboratories, said in a press release. "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."

The need to stop or slow the progression of TNBC is critical, as disease recurrence can be as high as 30 to 40 percent after standard neoadjuvant chemotherapy and surgery, even when the cancer is diagnosed early. TNBC is more common in people younger than age 50, and is more likely to be diagnosed in Black women and Hispanic women. The majority of breast cancers diagnosed in people with an inherited BRCA mutation are TNBC. "Metastatic TNBC is difficult to treat and has a poor prognosis, therefore prevention of metastatic disease is crucial," Dr. Adams says.

Physicians and researchers will be watching how well pembrolizumab performs over the long-term and whether other immunotherapy drugs may be able to provide similar or improved benefits as part of a comprehensive treatment approach to TNBC.

Metastatic Triple-Negative Breast Cancer Treatments To Consider

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James Roland has been a health journalist since 2007, not long after his father passed away of non-Hodgkin's lymphoma. Read More

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