Phase II study of celecoxib and trastuzumab in metastatic breast cancer patients who have progressed after prior trastuzumab-based treatments.

Purpose: Preclinical studies demonstrate a link between overexpression of HER-2/neu and cyclooxygenase-2 (COX-2) activity. To explore the possibility that COX-2 is a therapeutic target, we conducted a phase II study of celecoxib, a selective COX-2 inhibitor, and trastuzumab in patients with HER-2/neu-overexpressing metastatic breast cancer that had progressed while receiving trastuzumab.

Experimental Design: Eligible patients had bi-dimensionally measurable or evaluable HER-2/neu-overexpressing metastatic breast cancer. HER-2/neu overexpression, defined as 2+ or 3+ by the HercepTest, was required. Patients had to have progressed despite prior trastuzumab-based therapy. Treatment consisted of celecoxib (400 mg twice daily) and trastuzumab.

Results: Twelve patients were enrolled (42% status post 1 regimen for metastatic disease 58% status post > 2 prior regimens (range of 2-6). Eleven patients were evaluable. There were no responses. Median duration of treatment was 9 weeks. One patient had stable disease at 3 months but progressed at 6 months. A second patient stopped treatment at 3 months because of unresolved grade 2 rash, felt to be related to celecoxib. Toxicities were generally grade 1 or 2. One patient (8%) experienced grade 3 toxicity (abdominal pain).

Conclusions: Celecoxib combined with trastuzumab is well tolerated. However, this combination in patients with HER2/neu-overexpressing, trastuzumab-refractory disease, was not active.