Bortezomib with or without irinotecan in relapsed or refractory colorectal cancer: results from a randomized phase II...

To evaluate the efficacy and toxicity of bortezomib with or without irinotecan, in patients with relapsed or refractory colorectal cancer (CRC).

Patients were randomly assigned in a 3:4 ratio to bortezomib 1.5 mg/m(2) (arm A) or bortezomib 1.3 mg/m(2) plus irinotecan 125 mg/m(2) (arm B). A treatment cycle of 21 days consisted of four bortezomib doses on days 1, 4, 8, and 11, plus, in arm B, irinotecan on days 1 and 8. The primary objective of this randomized, multicenter, open-label, phase II study was to determine tumor response to treatment. Secondary objectives were safety and tolerability.

A preplanned interim analysis to assess efficacy revealed inadequate activity, resulting in early termination of this study. A total of 102 patients were treated, 45 in arm A and 57 in arm B. Baseline characteristics were comparable. The investigator-assessed response rate was 0 in arm A and 3.5% in arm B (all partial responses). Adverse events in both treatment arms were as expected, with no significant additive toxicity. The most common grade >or= 3 adverse events reported, per patient, during the study were fatigue (27%), vomiting (13%), nausea (11%), and peripheral sensory neuropathy (11%) in arm A, and diarrhea (33%), fatigue (25%), neutropenia (23%), thrombocytopenia (18%), dyspnea (12%), abdominal pain (12%), dehydration (12%), and anemia (11%) in arm B.

Bortezomib alone or in combination with irinotecan was not effective in patients with relapsed or refractory CRC.