Patients with relapsed/refractory (R/R) metastatic colorectal cancer (mCRC) who were previously treated with irinotecan may benefit from monotherapy with labetuzumab govitecan, according to a study published in the Journal of Clinical Oncology.1

For this dose-finding phase 1/2 trial (ClinicalTrials.gov Identifier: NCT01605318), researchers assigned 86 patients with R/R mCRC to 4 cohorts and administered intravenous labetuzumab govitecan twice a week at 4 mg/kg and 6 mg/kg on weeks 1 and 2 of 3-week cycles, or 8 mg/kg and 10 mg/kg once weekly. Eligible patients had received a median of 5 prior treatment regimens, 1 of which must have included irinotecan.

After labetuzumab treatment, 38% of patients experienced tumor and plasma carcinoembryonic antigen reduction from baseline. Forty-two patients achieved stable disease and 1 patient achieved a partial response with a sustained response for more than 2 years.

Median progression-free survival was 3.6 months and overall survival was 6.9 months.

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The rates of adverse events (AE) were similar between the 4 cohorts. The most frequently reported grade 3 and higher AEs were neutropenia, anemia, leukopenia, and diarrhea. Other frequently reported AEs included nausea, vomiting, diarrhea, and fatigue.

Researchers also investigated the pharmacokinetic profile and immunogenic profile of labetuzumab govitecan. Median half-life was found to be 16.5 hours and there was no evidence of antidrug/anti-antibody antibodies.

Upon analysis of the findings, the once weekly dosing schedules of labetuzumab demonstrated were selected for further study

The authors of the study concluded by saying, “additional clinical studies, especially those in which labetuzumab govitecan is combined with other agents (eg, replacing irinotecan FOLFOXIRI), are warranted.”

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