Matsuda N, et al. - Researchers investigated the safety and efficacy of the anti–epidermal growth factor receptor (EGFR) antibody panitumumab in combination with neoadjuvant chemotherapy in patients with primary human epidermal growth factor receptor 2 (HER2)-negative inflammatory breast cancer (IBC). In this work, the combination displayed the highest pathologic complete response (pCR) rate ever reported in triple-negative IBC.

Methods

• From 2010 to 2015, women with primary HER2-negative IBC were enrolled for this study.
• Patients received panitumumab plus neoadjuvant chemotherapy and were followed-up for a median of 19.3 months.
• Before and after the first dose of panitumumab, researchers collected tumor tissues which were subjected to immunohistochemical staining and RNA sequencing analysis to identify biomarkers predictive of pCR.
• They administered to patients 1 dose of panitumumab (2.5 mg/kg) followed by 4 cycles of panitumumab (2.5 mg/kg), nab-paclitaxel (100 mg/m²), and carboplatin weekly and then 4 cycles of fluorouracil (500 mg/m²), epirubicin (100 mg/m²), and cyclophosphamide (500 mg/m²) every 3 weeks.
• pCR rate was the primary end point; safety was the secondary end point.
• Biomarkers predictive of pCR were assessed as the exploratory objective.

Results

• Researchers gathered 47 patients; of these, 7 were ineligible.
• Of the 40 enrolled women (median age 57 [range, 23-68] years), 29 (72%) were postmenopausal.
• Because of toxic effects (n=2) or distant metastasis (n=1), therapy could not be completed in three patients.
• They identified triple-negative IBC in 19 patients, and hormone receptor–positive IBC in 21 patients.
• In this study, the pCR and pCR rates were overall 11 of 40 (28%; 95% CI, 15%-44%), triple-negative IBC was 8 of 19 (42%; 95% CI, 20%-66%), and hormone receptor–positive/HER2-negative IBC, was 3 of 21 (14%; 95% CI, 3%-36%).
• Hospitalization of 10 patients was reported for treatment-related toxic effects, including 5 with neutropenia-related events during treatment with panitumumab, nab-paclitaxel, and carboplatin.
• No treatment-related deaths were reported.
• Skin rash was identified as the most frequent nonhematologic adverse event.
• They identified several potential predictors of pCR, including pEGFR expression and COX-2 expression.