The US Food and Drug Administration (FDA0 has granted its first approval to an immunotherapy regimen for breast cancer. On March 8 the FDA gave accelerated approval to atezolizumab immunotherapy plus nab-paclitaxel chemotherapy for the treatment of adults with PD-L1-positive, unresectable, locally advanced or metastatic triple-negative breast cancer (TNBC) that cannot be surgically removed.
Triple negative breast cancers lack expression of estrogen and progesterone receptors and do not overexpress human epidermal growth factor 2 (HER2). Chemotherapies such as Abraxane (nab-paclitaxel) can be used, but median survival is still estimated to be less than 18 months.
Every year about 300,000 women are diagnosed globally with triple-negative breast cancer, an aggressive disease with limited treatment options. Approximately 15 percent of breast cancers are triple-negative, according to the National Breast Cancer Foundation. The protein PD-L1 may be found in roughly a fifth of those cancers. Triple-negative breast cancer is most likely to affect Hispanic and African-American women and those with a BRCA1 gene mutation, as well as women in their 40s and 50s.
The approval of atezolizumab (Tecentriq from Genentech) plus nab-paclitaxel (Abraxane from Celgene) applies to patients whose tumors express PD-L1 in an FDA-approved test. The combination therapy is only cleared for PD-L1 positive patients, accounting for about 40 percent of the broader TNBC population. Tecentriq was previously approved to treat other specific types of urinary and lung cancers.
Atezolizumab is a monoclonal antibody designed to bind with PD-L1 expressed on tumor cells and tumor-infiltrating immune cells, inhibiting its interactions with both PD-1 and B7.1 receptors. Tecentriq binds with a protein called PD-L1 expressed on tumor cells and tumor-infiltrating immune cells, blocking its interactions with both PD-1 and B7.1 receptors. By inhibiting PD-L1, Tecentriq, which may enable the activation of T cells, has the potential to be used as a foundational combination partner with cancer immunotherapies, targeted medicines and various chemotherapies across a broad range of cancers.
Accelerated approval is based on PFS data from the ongoing randomized, phase 3 IMpassion130 study. The FDA grants accelerated approvals to “drugs that treat serious conditions, and that fill an unmet medical need” based on data that suggests a clinical benefit. Ongoing approval may require substantiation and description of clinical benefit in confirmatory trials that would result in traditional FDA approval.
The multicenter, double-blind IMpassion130 study is evaluating the safety and efficacy of atezolizumab and nab-paclitaxel vs. placebo and nab-paclitaxel among 902 patients who had no previous systemic therapy for metastatic disease. The atezolizumab plus nab-paclitaxel group had a safety profile consistent with the known safety of each drug, and the combination yielded no new safety signals.
According to Hayley Dinerman, executive director of the Triple Negative Breast Cancer Foundation, “The Tecentriq regimen is an exciting new treatment option for certain people living with metastatic, triple-negative breast cancer, a difficult-to-treat form of the disease. Chemotherapy alone has been the mainstay of treatment for many years, so it’s encouraging to now have an immunotherapy combination available for people with PD-L1 positive disease.”
The FDA’s decision followed an October study published in the New England Journal of Medicine. That study determined that the therapy extended progression-free survival?—?the amount of time in which a patient’s cancer does not worsen. “In the PD-L1 subgroup, the median progression-free survival for those receiving the combination treatment was 7.4 months, versus 4.8 months for those getting the chemotherapy with placebo,” the FDA said.