Study Assesses Biosimilar for the Treatment of HER2-Positive Breast Cancer

CT-P6, a biosimilar to trastuzumab, effectively treated patients with HER2-Positive early-stage breast cancer and had a similar safety profile to trastuzumab, according to the findings of a recent study.

The randomized, double-blind, active-controlled phase 3 trial included 549 patients with stage I-IIIa operable HER2-positive breast cancer. A total of 271 patients were randomly assigned to receive CT-P6 and 278 patients were randomly assigned to receive trastuzumab. All patients received treatment in 8 cycles, each lasting 3 weeks, for 24 weeks in conjunction with neoadjuvant docetaxel and FEC therapy. Surgery was performed within 3 to 6 weeks of the final neoadjuvant study drug dose, and was followed by an adjuvant treatment period that lasted up to 1 year. The primary endpoint was pathological complete response, and the long-term safety and efficacy of CT-P6 was assessed over 3 years.
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Overall, the proportion of patients who achieved pathological complete response was similar between the groups. Pathological complete response occurred in 46.8% patients (116 out of 248 patients) who received CT-P6 and in 50.4% (129 out of 256 patients) of patients who received trastuzumab.

Serious adverse events were reported in 19 out of 271 patients (7%) in the CT-P6 group compared with 22 out of the 278 patients (8%) in the trastuzumab group. The most frequent adverse events were febrile neutropenia and neutropenia.

In addition, grade 3 or worse treatment-related adverse events occurred in 17 patients (6%) in the CT-P6 group compared with 23 patients (8%) in the trastuzumab group. Neutropenia was the most frequent adverse event reported among these patients.

“CT-P6 showed equivalent efficacy to reference trastuzumab and adverse events were similar,” the researchers concluded. “Availability of trastuzumab biosimilars could increase access to this targeted therapy for HER2-positive early-stage cancer.”

—Melissa Weiss

Reference:

Stebbing J, Baranau Y, Baryash V, et al. CT-P6 compared with reference trastuzumab for HER2-positive breast cancer: a randomised, double-blind, active-controlled, phase 3 equivalence trial [published online June 4, 2017]. Lancet Oncol. http://dx.doi.org/10.1016/S1470-2045(17)30434-5