A phase II study of piritrexim in patients with advanced squamous head and neck cancer

Piritrexim (PTX) is a newly developed lipid-soluble folate antagonist that crosses the cell membrane by a simple, rapid, carrier-independent diffusion process. A Phase II study was conducted to evaluate the activity of PTX in 34 patients with previously chemotherapy-naive squamous cell cancer of the head and neck area (SCCHN). Among them, 30 patients had received previous radiation therapy and/or surgery. Of 33 patients who could be examined, 3 had a complete response (CR), 6 had a partial response (PR), 11 had no change, and 13 had disease progression. The overall response rate (CR + PR) was 27% (9 of 33; 95% confidence interval, 13% to 46%). The response duration ranged from 36 to 360 + days (median, 162) and was similar to the best studies reported with methotrexate. The three most severe side effects (Grades 3 and 4 by World Health Organization criteria) were leukopenia, thrombocytopenia, and mucositis. These occurred in 41%, 26%, and 15% of the 34 patients, respectively. This study established PTX as an agent with some activity in SCCHN. The use of PTX in combination chemotherapeutic regimens needs to be explored.