Monotherapy with labetuzumab govitecan is active in heavily pretreated patients with metastatic colorectal cancer (mCRC) and has an acceptable safety profile, a study presented at the American Academy for Cancer Research (AACR) Annual Meeting 2016 has shown.1
Because there continues to be an urgent need for better treatment strategies to improve outcomes of patients with mCRC, researchers developed labetuzumab govitecan, a conjugate of a humanized antibody to CEACAM5 that is linked site-specifically to the active metabolite of irinotecan SN-38.
For the phase 2 study, researchers enrolled 86 patients with mCRC with a carcinoembryonic antigen level greater than 5 ng/mL and who had received a median number of 5 prior therapies, including prior irinotecan-containing therapy. Participants received labetuzumab govitecan at doses ranging from 4 to 10 mg/kg once or twice weekly for 2 weeks of each 3-week cycle. Treatment was continued until disease progression or unacceptable toxicity.
Results showed that the most common treatment-related adverse events were nausea, fatigue, vomiting, and diarrhea. Grade 3 and 4 treatment-related adverse events included neutropenia (15%), anemia (6%), and diarrhea (2%). All patients who required toxicity-related dose reductions or interruptions recovered with major consequences.
In terms of efficacy, the weekly regimen appeared superior with respect to disease control rate, progression-free survival, and overall survival compared with the twice weekly regimen. Of the patients who received 10 mg/kg every week, 78% had stable disease vs 7% of those who received 6 mg/kg twice weekly.
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Researchers found that median progression-free survival with labetuzumab govitecan 10 mg/kg once weekly was 4.6 months compared with 3.7 months for 6 mg/kg twice weekly. Median overall survival was 9.3 months and 7.4 months, respectively.
Based on these findings, researchers will assess labetuzumab govitecan at a dose of 10 mg/kg weekly for 2 weeks in 21-day cycles for future studies.
- Dotan E, Cohen SJ, Starodub AN, et al. Labetuzumab govitecan (IMMU-130), an anti-CEACAM5/SN-38 antibody-drug conjugate, is active in patients (pts) with heavily pretreated metastatic colorectal cancer (mCRC): phase II results. Oral presentation at: AACR Annual Meeting 2016; April 16-20, 2016; New Orleans, LA.