A phase I study of radiation therapy and twice-weekly gemcitabine and cisplatin in patients with locally advanced pancreatic cancer.

Abstract

In vitro studies suggest that low-dose gemcitabine sensitizes cells to radiation therapy and that this effect persists for 48 h after drug exposure. Cisplatin is a radiation sensitizer and is also synergistic with gemcitabine in some in vitro tumor systems. Gemcitabine's radiosensitizing properties can theoretically be exploited by twice-weekly administration. This study assessed toxicity in patients with pancreatic cancer treated with radiation therapy, gemcitabine, and cisplatin. Patients with locally advanced pancreatic or gastric cancer were eligible. Gemcitabine and cisplatin were given twice weekly for 3 weeks during radiation therapy (50.4 Gy in 28 fractions). The starting dose of gemcitabine was 5 mg/m(2) i.v. The starting dose for cisplatin was 5 mg/m(2). Chemotherapy doses escalated every 3 to 6 patients according to a standard Phase I study design. Twenty-four evaluable patients, all with pancreatic cancer, were treated on this protocol. Grade 3 neutropenia occurred in 2 patients, Grade 3 thrombocytopenia occurred in 2, and Grade 4 lymphopenia occurred in 1. There was no clear relationship between chemotherapy dose and hematologic toxicity. The most common Grade 3-4 nonhematologic toxic responses were vomiting (7 patients) and nausea (7 patients). Dose-limiting toxicity consisting of Grade 4 nausea and vomiting occurred in 2 of 3 patients at dose Level 6 (gemcitabine 45 mg/m(2) i.v. and cisplatin 10 mg/m(2) i.v.). Six patients were treated at dose Level 5 (gemcitabine 30 mg/m(2) i.v. and cisplatin 10 mg/m(2) i.v.) without dose-limiting toxicity. Gemcitabine 30 mg/m(2) i.v. twice weekly and cisplatin 10 mg/m(2) i.v. twice weekly may be given concurrently with radiation therapy (50.4 Gy in 28 fractions) with acceptable toxicity.