Preclinical studies suggest that additive or synergistic effects are achieved with the combination of pemetrexed plus gemcitabine. A phase 1 study of pemetrexed plus gemcitabine given every 2 weeks demonstrated encouraging preliminary efficacy against head and neck squamous cell cancer (HNSCC).
This was an open-label, single-institution, single-arm, phase 2 study for patients who had received no more than 2 cytotoxic regimens for recurrent and/or metastatic HNSCC. All patients received pemetrexed 500 mg/m² intravenously plus gemcitabine 1250 mg/m² intravenously every 2 weeks with vitamin B12 and folate support. The primary endpoint was the objective response rate according to Response Evaluation Criteria in Solid Tumors (RECIST); secondary endpoints were to estimate overall survival and to evaluate safety and tolerability.
Twenty-five patients received therapy. All patients had received prior radiotherapy, and half had received prior cytotoxic chemotherapy for recurrent and/or metastatic disease. Neutropenia (grade ≥ 3) occurred in 24% of patients. Four patients (16%) had a partial response (PR) according to RECIST, and 5 additional patients (20%) had objective tumor reductions of > 20 but < 30% did not meet RECIST criteria for a PR. The median overall survival for all treated patients was 8.8 months.
Treatment with pemetrexed plus gemcitabine every 2 weeks with vitamin support generally was well tolerated. The results of this study provided further evidence that pemetrexed may have significant palliative activity against advanced HNSCC.