Why Merrimack Pharma Is Terminating Its Midstage Lung Cancer Study

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Merrimack Pharmaceuticals Inc. (NASDAQ: MACK) shares dropped early on Friday after the company announced that it would be terminating its mid-stage SHERLOC study in patients with non-small cell lung cancer. Specifically, this was the Phase 2 clinical trial evaluating MM-121 in combination with docetaxel.

Ultimately, this decision was made in agreement with the chair of the independent Data Safety Monitoring Board following an interim analysis that was triggered by the occurrence of 75% of events required for trial completion.

In total, 88% of required events were captured in this analysis, and while the safety profile was consistent with MM-121’s previously reported safety profile, the data demonstrated that the addition of MM-121 to docetaxel did not improve progression free survival over docetaxel alone in this patient population. Since futility was observed, the decision has been made to terminate the study.

Based on these results, Merrimack is implementing a comprehensive review of its drug candidate pipeline, including assessing the impact of these results on the continued development of MM-121. MM-121 is also currently being evaluated in the SHERBOC study in patients with heregulin positive, hormone receptor positive, ErbB2 (HER2) negative, metastatic breast cancer.

Sergio Santillana, M.D., M.Sc., chief medical officer of Merrimack, commented:

We are very disappointed by the outcome of this study, in particular for patients and families facing this difficult diagnosis. We deeply appreciate the support from all investigators, patients and their families who participated in this trial. We also want to recognize our team’s efforts and commitment to the development of MM-121 in non-small cell lung cancer over the past several years.

Excluding Friday’s move, Merrimack has underperformed the broad markets, with the stock down 61% in the past 52 weeks. In just 2018 alone, the stock is down closer to 50%.

Shares of Merrimack closed Thursday at $5.16, with a consensus analyst price target of $7.00 and a 52-week trading range of $4.56 to $13.16. Following the announcement, the stock was down about 30% at $3.60 in early trading indications Friday.