Merrimack Pharmaceuticals, Inc. announced that additional analyses were presented on January 16, 2015 from the Phase 3 NAPOLI-1 study of MM-398 (irinotecan liposome injection), also known as 'nal-IRI' in patients with metastatic pancreatic cancer previously treated with gemcitabine-based therapy. The data were presented by Li-Tzong Chen, M.D., Ph.D. in an oral session at the American Society of Clinical Oncology (ASCO) 2015 Gastrointestinal Cancers Symposium in San Francisco, CA. Merrimack and Baxter International's biopharmaceutical business are collaborating on the development and commercialization of MM-398 outside of the United States and Taiwan.

PharmaEngine, Inc. holds the rights to commercialize MM-398 in Taiwan. Additionally, Merrimack presented preclinical and clinical data from studies of its investigational agents MM-141 and MM-151 in pancreatic and colorectal cancer, respectively. An investigator-sponsored study of MM-398 in colorectal cancer was also presented.

The primary analysis, presented at ESMO GI, demonstrated a statistically significant advantage in overall survival with an unstratified hazard ratio of 0.67 (95% CI [0.49-0.92], p=0.0122), and a median of 6.1 months for the combination of MM-398 plus 5-FU and leucovorin compared to 4.2 months in the control arm. Data presented at ASCO GI showed: Stratified analysis, which accounts for pre-specified prognostic factors included in the study randomization stratification, resulted in an overall survival hazard ratio of 0.57 (95% CI [0.41-0.80], p=0.0009). A forest plot sensitivity analysis of additional prognostic factors such as line of treatment, stage at diagnosis, prior lines of therapy, time since initial diagnosis, and time since last prior therapy, supported the primary efficacy results obtained.

Evaluation of the Per Protocol population (defined by patients who were able to remain on treatment for >6 weeks) supported the primary Intent to Treat analysis and demonstrated a median overall survival of 8.9 months for MM-398 in combination with 5-FU and leucovorin versus 5.1 months in the control arm (stratified HR=0.47, 95% CI [0.29-0.77], p=0.0018). The safety profile of the MM-398 combination was reported to be manageable and consistent with previously reported safety results, with the most frequent adverse events including neutropenia (20% in the combination arm vs. 2% in the control arm), fatigue (14% vs.

4%) and gastrointestinal effects such as diarrhea (13% vs. 5%) and vomiting (11% vs. 3%).