According to a new study published online ahead of print in the Journal of Clinical Oncology, researchers have found that iniparib plus gemcitabine and carboplatin did not meet prespecified criteria for the primary endpoints of progression-free survival and overall survival in patients with metastatic triple-negative breast cancer.

For this phase 3, multicenter, open-label study, researchers randomly assigned 519 women with stage 4 or locally recurrent triple-negative breast cancer to receive gemcitabine plus carboplatin or the same chemotherapy regimen in addition to iniparib.

Of the patients that received the three-drug combination, 65% were 50 years of age or older, 98% had an Eastern Cooperative Oncology Group performance status of 0 or 1, 89% had received prior chemotherapy, and 57% were receiving this treatment as first-line therapy.

Patients received gemcitabine 1,000 mg/m2 and carboplatin area under the curve 2 on days 1 and 8, and patients in the three-drug group also received iniparib 5.6 mg/kg on days 1, 4, 8, and 11. Cycles were repeated every 3 weeks.1

Results showed no statistically significant difference for overall survival (hazard ratio [HR]=0.88; 95% confidence interval [CI], 0.69, 1.12; P =0.28) or progression-free survival (HR=0.79; 95% CI, 0.65,0.98; P=0.98) between both groups.

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The researchers performed an exploratory analysis and found that patients receiving iniparib plus gemcitabine and carboplatin had improved overall survival (HR=0.65; 95% CI, 0.46,0.91) or progression-free survival (HR=0.68; 95% CI, 0.50,0.92) compared with those who received gemcitabine and carboplatin only.

The most common adverse effects in both groups were fatigue, nausea, constipation, vomiting, headache, and dyspnea. Incidence rates were similar among both groups.