June 19, 2013
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Addition of cetuximab to cisplatin doubled response in metastatic breast cancer

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The addition of cetuximab to cisplatin doubled the overall response rate and prolonged OS compared with cisplatin alone in patients with metastatic triple-negative breast cancer, according to results of a randomized phase 2 study.

However, the combination treatment did not meet the predetermined response rate of more than 20%.

The open-label study included 173 patients who had undergone a maximum of one prior chemotherapy.

 

José Baselga

José Baselga, MD, PhD, physician-in-chief at Memorial Sloan-Kettering Cancer Center, and colleagues randomly assigned 115 patients to cisplatin plus cetuximab (Erbitux, Eli Lilly), an anti-epidermal growth factor receptor monoclonal antibody, and 58 patients to cisplatin alone. Patients received no more than six cycles of treatment.

Best overall response rate, defined as the proportion of patients with a confirmed complete or partial response, served as the primary outcome measure. Secondary outcome measures were PFS, OS and safety.

Disease progressed in 31 patients assigned to cisplatin alone; these patients then switched to the combination arm (n=21) or to cetuximab alone (n=10).

The overall response rate was 20% among patients assigned to cetuximab plus cisplatin vs. 10% among patients assigned to cisplatin alone (OR=2.13; 95% CI, 0.81-5.59). The median time to response was 1.4 months in the combination arm vs. 1.3 months in the cisplatin-alone arm (HR=0.75; 95% CI, 0.26-2.17). 

Researchers also reported superior median PFS (3.7 months vs. 1.5 months; HR=0.67; 95% CI, 0.47-0.97) and median OS (12.9 months vs. 9.4 months; HR=0.82; 95% CI, 0.56-1.20) among those assigned to the combination regimen.

Grade 3-4 adverse events that occurred in patients assigned to the combination treatment included acne-like rash (17%), neutropenia (11%) and fatigue (10%).

“This was a complex study to analyze,” Baselga told HemOnc Today. “In order for us to determine the addition of cetuximab to cisplatin was of clinical value, the overall response rate had to be greater than 20%. We were not able to show this, despite a lot of previous studies that suggested cisplatin was more active in triple-negative breast cancer than what we observed.

“However, the most important thing that our study showed is that the EGFR receptor is a target for triple-negative breast cancer, because we doubled the response rate and also had an increase in PFS,” Baselga said. “There is something here, and we need to figure out how to move this forward.”