Combination pertuzumab, trastuzumab, and docetaxel provided better responses than did placebo, trastuzumab, and docetaxel in Asian patients with ERBB2-positive early or locally advanced breast cancer, according to a phase 3 trial.
The safety profile of the combination regimen was similar between the treatment arms and in accordance with that of pertuzumab alone, reported Zhimin Shao, MD, of Fudan (Shanghai) University Cancer Center, and colleagues. The study was published in JAMA Oncology.
The randomized, placebo-controlled, phase 3 PEONY study included 329 women with ERBB2-positive early or locally advanced disease. The effects of adding pertuzumab to trastuzumab and docetaxel was studied in 23 centers throughout Asia.
Prior to surgery, study subjects in the treatment arm received intravenous pertuzumab at a loading dose of 840 mg followed by 420 mg, trastuzumab at a loading dose of 8 mg/kg followed by 6 mg/kg, and 75 mg/m2 of docetaxel, while patients in the placebo arm received placebo, trastuzumab, and docetaxel. Both regimens were administered every 3 weeks for a total of four cycles.
Post surgery, study patients received intravenous fluorouracil, cyclophosphamide, and epirubicin for a total of 3 cycles, followed by pertuzumab plus trastuzumab or placebo plus trastuzumab for a total of 13 cycles.
The primary outcome was the total pathologic complete response rate assessed at the completion of surgery.
After analysis, the researchers found that total pathologic complete response rates were significantly higher for patients in the pertuzumab arm (39.3%) compared with the placebo arm (21.8%) (difference, 17.5%; P = .001).
With respect to safety, the rates of common adverse events were similar between the groups, with the exception of diarrhea (38.5% in the pertuzumab arm vs. 16.4% in the placebo arm). The incidences of serious toxicities were slightly higher in the pertuzumab arm (10.1%) compared with the placebo arm (8.2%).
“Of the most common grade 3 or higher adverse events, there was a higher incidence of neutropenia in the pertuzumab group (38.1% vs. 32.7%),” they reported.
The researchers acknowledged a key limitation of the study was the short duration of follow-up. As a result, some secondary outcome data were immature at the time of the analysis.
“The PEONY trial adds to the totality of the data showing the benefit of pertuzumab and trastuzumab with chemotherapy in ERBB2-positive early breast cancer,” they concluded.
The authors reported financial affiliations with F. Hoffmann-La Roche Ltd., which funded the study, and Genentech.
SOURCE: Shao Z et al. JAMA Oncol. 2019 Oct 24. doi: 10.1001/jamaoncol.2019.3692.