(HealthDay News) — For patients with untreated stage II or III triple-negative breast cancer, pembrolizumab plus neoadjuvant chemotherapy, compared with placebo plus neoadjuvant chemotherapy, is associated with a significantly higher rate of pathological complete response, according to a study published in the Feb. 27 issue of the New England Journal of Medicine.

Peter Schmid, M.D., from the Queen Mary University of London, and colleagues conducted a phase 3 trial involving patients with previously untreated stage II or III triple-negative breast cancer. Patients were randomly assigned to receive neoadjuvant therapy with four cycles of pembrolizumab every three weeks plus paclitaxel and carboplatin or placebo every three weeks plus paclitaxel and carboplatin; both groups then received four additional cycles of pembrolizumab or placebo and received doxorubicin-cyclophosphamide or epirubicin-cyclophosphamide.

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At the first interim analysis involving the first 602 patients who were randomized, the researchers found the percentage with a pathological complete response was 64.8 and 51.2 percent in the pembrolizumab-chemotherapy and placebo-chemotherapy groups, respectively. Overall, 7.4 and 11.8 percent of the pembrolizumab-chemotherapy and placebo-chemotherapy groups, respectively, had disease progression that precluded definitive surgery, had local or distant recurrence or a second primary tumor, or died from any cause after a median follow-up of 15.5 months (hazard ratio, 0.63). The incidence of treatment-related adverse events of grade 3 or higher was 78 and 73 percent in the pembrolizumab and placebo groups, respectively.


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“The benefit with respect to pathological complete response was observed across most prognostic risk categories,” the authors write.

The study was funded by Merck, the manufacturer of pembrolizumab.

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