November 2nd 2004
Single-agent gemcitabine (Gemzar) is the standard of chemotherapyfor advanced pancreatic cancer, with no phase III trials to date havingshown significantly improved survival with gemcitabine-based combinationsvs single-agent treatment. The multitargeted antifolate agentpemetrexed (Alimta) shows synergistic effects in vitro in combinationwith gemcitabine, and activity and good tolerability when used as singleagenttreatment in advanced pancreatic cancer. In a phase II trial inpatients with advanced pancreatic cancer, the combination ofgemcitabine at 1,250 mg/m2 on days 1 and 8 plus pemetrexed at 500mg/m2 on day 8 after gemcitabine every 21 days resulted in a mediansurvival of 6.5 months and a 1-year survival rate of 29%. Neutropeniawas the primary toxicity, with grade 4 toxicity in 51% of patients. Thepromising results of this trial prompted the initiation of a phase IIItrial comparing gemcitabine at 1,000 mg/m2 on days 1, 8, and 15 every28 days vs the 21-day gemcitabine/pemetrexed regimen given with vitaminsupplementation in patients with pancreatic cancer. The primaryoutcome measure was overall survival, with secondary measures includingresponse rate, progression-free survival, and quality of life.While an increase in response and time to progression was reported forthe gemcitabine/pemetrexed combination, there were no significantdifferences in survival between treatment arms.