Purpose Epidermal growth factor receptor is overexpressed in metastatic triple-negative breast cancers (mTNBCs), an aggressive subtype of breast cancer. Our randomized phase II study investigated cisplatin with or without cetuximab in this setting. Patients and Methods Patients who had received no more than one previous chemotherapy regimen were randomly assigned on a 2:1 schedule to receive no more than six cycles of cisplatin plus cetuximab or cisplatin alone. Patients receiving cisplatin alone could switch to cisplatin plus cetuximab or cetuximab alone on disease progression. The primary end point was overall response rate (ORR). Secondary end points studied included progression-free survival (PFS), overall survival (OS), and safety profiles. Analyses included a significance level of α = .10 with no adjustments for multiplicity. Results The full analysis set comprised 115 patients receiving cisplatin plus cetuximab and 58 receiving cisplatin alone; 31 patients whose disease progressed on cisplatin alone switched to cetuximab-containing therapy. The ORR was 20% (95% CI, 13 to 29) with cisplatin plus cetuximab and 10% (95% CI, 4 to 21) with cisplatin alone (odds ratio, 2.13; 95% CI, 0.81 to 5.59; P = .11). Cisplatin plus cetuximab resulted in longer PFS compared with cisplatin alone (median, 3.7 v 1.5 months; hazard ratio [HR], 0.67; 95% CI, 0.47 to 0.97; P = .032). Corresponding median OS was 12.9 versus 9.4 months (HR, 0.82; 95% CI, 0.56 to 1.20; P = .31). Common grade 3/4 adverse events included acne-like rash, neutropenia, and fatigue. Conclusion While the primary study end point was not met, adding cetuximab to cisplatin doubled the ORR and appeared to prolong PFS and OS, warranting further investigation in mTNBC.

Background: The epidermal growth factor receptor (EGFR) plays a role in triple-negative (estrogen receptor-, progesterone receptor-, HER2-negative) breast cancer (TNBC). This randomized, phase II study investigated the combination of the EGFR monoclonal antibody cetuximab and cisplatin in the treatment of metastatic (m) TNBC. Methods: Patients (pts) with mTNBC who had received ≥1 prior chemotherapy regimen for metastatic disease, were randomized 2:1 to treatment with either: cetuximab (400 mg/m2 initial dose then 250 mg/m2 weekly) + ≥6x 3-weekly cycles of cisplatin (75 mg/m2, d1); or ≥6x 3-weekly cycles of cisplatin alone. In the cisplatin arm, pts with disease progression (PD) during the 6 cisplatin cycles could switch to cetuximab plus cisplatin and those with PD after the 6 cycles could receive cetuximab alone. The primary endpoint was best overall response. Simultaneous null hypotheses assumed that the overall response rate (ORR) in the combination arm was ≥20% and that the ORRs were equal in both arms. Secondary endpoints included progression-free survival (PFS), overall survival (OS) and safety. All statistical tests were performed at alpha-level 0.1 Results: 173 pts were included in the intention-to-treat population: 115 were randomized to cetuximab/cisplatin and 58 to cisplatin. The cetuximab/cisplatin and cisplatin arms were well balanced for patient and disease characteristics (randomization strata, 73% first and 27% second line in both arms). Differences included: age ≥65 years (19.1% vs 12.1%) and lung metastases (55.7% vs 44.8%). 30 pts receiving cisplatin alone switched to cetuximab/cisplatin after first PD. 79.6% of patients on cetuximab/cisplatin and 73.7% on cisplatin received ≥90% of the relative dose intensity of cisplatin. Adverse events (AEs) were manageable and in line with what was expected from the different agents (grade 3/4 AEs are shown in the Table). Grade 3/4 AEs (%) Adding cetuximab to cisplatin nearly doubled the ORR: 20.0% (95% CI 13.1%, 28.5%) vs 10.3% (95% CI 3.9%, 21.2%) (p=0.5 for testing ORR against 20.0%), with an odds ratio of 2.126 (90% CI 0.945, 4.786, p=0.11). Cetuximab/cisplatin was associated with a significant 32.5% reduction in the risk of disease progression compared with cisplatin alone HR 0.675 (95% CI 0.470, 0.969, p=0.032). Median PFS times were 3.7 and 1.5 months, respectively. The benefits of cetuximab/cisplatin over cisplatin on ORR and PFS were observed consistently across sub-groups (according to patient, disease and treatment characteristics), but sample sizes were small. OS results will be presented at the meeting. Conclusions: Adding cetuximab to cisplatin increased the ORR compared with cisplatin alone and significantly improved PFS in mTNBC. Safety was manageable. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD01-01.