Panitumumab, Gemcitabine, and Carboplatin as Treatment for Women with Metastatic Triple-Negative Breast Cancer: A Sarah Cannon Research Institute Phase 2 Trial

Abstract Background Triple-negative breast cancer (TNBC) is a subtype with poor prognosis, and treatment options limited to chemotherapy. As the epidermal growth factor receptor (EGFR) is overexpressed in up to 70% of these tumors, this phase 2 trial was designed to evaluate the efficacy and safety of panitumumab in combination with gemcitabine and carboplatin as first- or second-line treatment for metastatic TNBC. Methods Adult women with metastatic TNBC with a maximum of one prior chemotherapy regimen were eligible. Patients received gemcitabine 1500 mg/m2 IV, carboplatin AUC = 2.5 IV, and panitumumab 6 mg/kg IV every 2 weeks. Treatment continued until disease progression or unacceptable toxicity, with disease evaluations every 6 weeks. The primary endpoint was PFS. Archival tissue was collected for correlative analysis, to include PIK3CA, p53, PTEN, EGFR, and K-ras status. Results Between 5/2010 and 8/2012, 71 women (median age 54 years; 14% de novo stage IV) were treated. At median follow-up of 11 months, the median PFS was 4.4 months (95% CI: 3.2, 5.5 months). The objective response rate was 42% (CR 1, PR 29). Treatment-related toxicity included: rash (70%), fatigue (52%), neutropenia (45%; 2 episodes of febrile neutropenia), and thrombocytopenia (45%). Conclusion While the addition of panitumumab was feasible, the results of this trial do not support addition of panitumumab to gemcitabine and carboplatin in the treatment of patients with TNBC.