Merrimack Pharmaceuticals Announces Phase 2 Study Of MM-121 Misses Primary Endpoint

Merrimack Pharmaceuticals

today announced results of a global, Phase 2, open-label, randomized study of MM-121 in combination with paclitaxel versus paclitaxel alone in patients with platinum-resistant or platinum-refractory advanced ovarian cancers. This study did not meet the primary endpoint of progression free survival in the overall population.  The hazard ratio (HR) for progression free survival (PFS) was 1.0 [95% CI 0.74 - 1.4]. Ongoing analysis of a pre-specified set of biomarkers mechanistically linked to ErbB3 signaling identified a potential subpopulation of patients benefiting from MM-121 treatment in combination with paclitaxel. When using a combination of two biomarkers, the hazard ratio for PFS was 0.37 [95% CI 0.2 - 0.8] in the 34% of patients who were biomarker positive. The hazard ratio for PFS in the biomarker negative population was 1.54 [95% CI 1.0 - 2.4]. An overall increase in all grades of gastrointestinal toxicities, including diarrhea (73.6% vs. 42.5%), vomiting (31.4% vs. 18.8%) and other mucosal toxicities such as rhinitis (7.1% vs. 1.3%), epistaxis (23.6% vs. 17.5%), stomatitis (22.1% vs. 10.0%) and mucosal inflammation