NEW YORKA regimen of twice-weekly gemcitabine (Gemzar) plus
radiation therapy in patients with unresectable pancreatic cancer
appears promising, according to results of a phase I dose escalation
study presented at the Chemotherapy Foundation Symposium XVII. The
twice-weekly delivery may be more cytotoxic than standard once-weekly
dosing, and gemcitabine may act as a radiation sensitizer, said A.
William Blackstock, MD, assistant professor of Radiation Oncology,
Wake Forest University, Winston-Salem, NC.
Laboratory studies have confirmed that gemcitabine is a
potent radiation sensitizer, and ongoing studies of the gemcitabine-radiation
interaction are expected to shed more light on the underlying
mechanism, he said.
In this study, Dr. Blackstock and his colleagues escalated
gemcitabine from 20 mg/m² to a maximum tolerated dose of 60 mg/m².
The agent was given as a 30-minute IV infusion each Monday and
Thursday for 5 weeks concurrent with 50.4 Gy of radiation delivered
over the course of 5 days. The optimal schedule was to give
gemcitabine within 72 hours of delivery of radiation. Dose-limiting
toxicities were nausea and vomiting, neutropenia, and
At 40 mg/m², the regimen was well tolerated, although
thrombocytopenia frequently necessitated a break in treatment during
the third week. Median survival in the 19-patient group was an
encouraging 12.3 months, Dr. Blackstock said.
Based on these findings, a phase II trial has been initiated through
the Cancer and Leukemia Group B (CALGB) to evaluate the efficacy of
twice-weekly gemcitabine plus radiation in locally advanced
unresectable pancreatic cancer. A second phase II study is looking at
the same approach as adjuvant therapy following surgery in resectable