Background: Oxaliplatin and raltitrexed both are active anticancer agents in the treatment of patients with advanced colorectal carcinoma: They have different mechanisms of action and toxicity profiles and have shown at least additive effects in experimental and preliminary clinical studies. The aim of this disease oriented Phase I-II study was to determine the maximum tolerated dose (MTD), the dose-limiting toxicities (DLT), and the objective response rate of this combination in patients with advanced colorectal carcinoma.
Methods: Between April 1998 and March 1999, 69 patients with measurable metastatic colorectal carcinoma who previously were unexposed to palliative chemotherapy were enrolled. In the Phase I part of the study, 27 patients were treated with 3-weekly courses of a fixed dose of raltitrexed (3 mg/m(2) given as a 15-minute intravenous infusion) followed by a 2-hour infusion of oxaliplatin, which was escalated in consecutive cohorts of three to six patients from 85 mg/m(2) to 100 mg/m(2), 120 mg/m(2), 130 mg/m(2), and 140 mg/m(2). After having defined the toxic dose, 42 additional patients were entered at one dose level below to define the therapeutic index of this combination more precisely.
Results: In the Phase I part of the study, during the first three dose levels, only one patient each experienced DLT (Grade 3 increase in transaminases, diarrhea, and stomatitis); at level 4, two of the first six patients entered had Grade 3 neutropenic infection or peripheral neurotoxicity, whereas dose level 5 (oxaliplatin 140 mg/m(2)) constituted the toxic dose with three of three patients experiencing DLT (Grade 3 asthenia, transient amaurosis, and diarrhea with Grade 4 neutropenia). Externally reviewed objective responses were noted in 9 of these 27 patients (33%), and stable disease occurred in 12 patients (44.4%). Among the 42 patients who were treated subsequently at the MTD level (Phase II portion), 20 patients (47.6%) responded (95% confidence interval, 32-62.6%), and 21 patients (50%) had stable disease. Their median progression free survival was 9.0 months, and the median overall survival, with 42 patients (67%) currently alive, is > 14.5 months. Treatment tolerance at the MTD was acceptable, with only 9 of 42 patients (21%) experiencing Grade 3-4 neutropenia; Grade 3 nonhematologic adverse reactions included increase in serum transaminases in 6 patients, peripheral neuropathy in 3 patients, diarrhea in 3 patients, and both stomatitis and emesis in only 1 patient each.
Conclusions: The described objective response and toxicity data, which are in agreement with preliminary results of other Phase I-II studies, support the promising therapeutic potential of this combination in the treatment of patients with advanced colorectal carcinoma. Due to its substantial antitumor activity, tolerance (at the recommended MTD level), and convenient 3-weekly outpatient administration schedule, further evaluation of this regimen seems warranted.
Copyright 2001 American Cancer Society.