Merrimack slides on ovarian cancer data
Merrimack Pharmaceuticals Inc. (NASDAQ:MACK) fell $0.64 (19%) to $2.74 on Wednesday after reporting that MM-121 plus paclitaxel missed the primary endpoint of improving progression-free survival (PFS) vs. paclitaxel alone in a Phase II trial to treat platinum-resistant or refractory advanced ovarian cancer. In August, Merrimack said a pre-specified interim analysis showed MM-121 would not meet the endpoint. At the time, the company said it would continue the trial based on "expectations of the potential for subgroup benefit." MM-121 is a human mAb against epidermal growth factor receptor 3 ( EGFR3; HER3; ErbB3).
On Wednesday, Merrimack said an ongoing analysis of an undisclosed pre-specified set of biomarkers mechanistically linked to EGFR3 signaling identified a potential subpopulation of patients benefiting from MM-121 plus paclitaxel. Merrimack also said an increase in the rate of pulmonary embolism was reported in the MM-121 plus paclitaxel arm compared to the paclitaxel alone arm (5% vs. 1.2%). The company said that none of the pulmonary embolisms were fatal, led to treatment discontinuation or were assessed as treatment-related by the study investigators. ...