Phase I studies of continuous-infusion paclitaxel given with standard aggressive radiation therapy for locally advanced solid tumors

Currently available therapies are unsatisfactory for locally advanced solid tumors of the lung, head and neck, and brain. Laboratory data suggest that the addition of paclitaxel (Taxol; Bristol-Myers Squibb Oncology, Princeton, NJ), a microtubule-stabilizing drug, to radiation therapy may result in significant radiation sensitization, perhaps because paclitaxel induces cell cycle arrest at G₂/M. Relatively low concentrations, 1 to 10 nmol/L, appear to be optimal for direct cytotoxicity and radiosensitization in vitro. Within this dose range, more prolonged exposure seems to result in higher response rates. We are conducting phase I trials designed to test continuous infusion (24 hours per day, 7 days per week) intravenous paclitaxel combined with standard curative-intent radiation therapy. To date, 22 patients are evaluable, and the maximum tolerated dose of paclitaxel has not been reached at up to 2.5 mg/m²/d. Observed toxicities include anemia, lymphopenia, mucositis, and cutaneous erythema/desquamation.