Merrimack Reports Ipsen Announcement of Approval By The US FDA of Onivyde (Irinotecan Liposome Injection) Plus 5 Fluorouracil/Leucovorin and Oxaliplatin (NALIRIFOX) as a First-Line Treatment for Metastatic Pancreatic Ductal Adenocarcinoma (mPDAC)

Merrimack Pharmaceuticals, Inc. (Nasdaq: MACK) (“Merrimack” or the “Company”) reported that Ipsen, SA (“Ipsen”) issued a press release today announcing the U.S. Food and Drug Administration has approved the supplemental new drug application for Onivyde (irinotecan liposome injection) plus 5 fluorouracil/leucovorin and oxaliplatin (NALIRIFOX) as a first-line treatment for people living with metastatic pancreatic ductal adenocarcinoma (mPDAC).

Under the terms of the 2017 Asset Purchase Agreement between Ipsen and Merrimack (the “Ipsen Agreement”), previously approved by Merrimack’s stockholders, this U.S. Food and Drug Administration approval triggers a $225 million milestone payment from Ipsen to Merrimack which is due on or before March 29, 2024.

“Today’s announcement is the culmination of nearly seven years of clinical trials and regulatory approval efforts by Ipsen following its 2017 purchase of the Onivyde technology from Merrimack. The Company has received several payments from the Ipsen Agreement including: a $575 million payment in 2017, a $5.7 Million working capital adjustment payment later that year, and a $5 million milestone payment in 2019” said Gary Crocker, Chairman of Merrimack’s Board of Directors. “The Board of Merrimack plans to hold a Special Meeting of Stockholders to approve a plan for a corporate dissolution and followed by a distribution of the proceeds to our stockholders from this new $225 million milestone payment, plus residual cash, net of corporate taxes and interest charges accruing under IRS installment sale rules, and other expenses.”

Merrimack’s Board of Directors has evaluated the likelihood of receiving additional milestone payments under the Ipsen Agreement and from the 2019 Agreement with Elevation Oncology (the “Elevation Agreement”) and has concluded that it is unlikely that any additional milestone payments from either agreement will become payable. Based on this analysis, Merrimack expects to hold a special meeting of stockholders by May of 2024 to seek approval for the adoption of a Plan of Dissolution including issuance of a liquidating dividend after the special meeting of stockholders. The Plan will include establishment of a liquidating trust for the benefit of stockholders in the unlikely event that Merrimack might receive any future milestone payments from Ipsen or Elevation Technology.