Merrimack Pharmaceuticals, Inc. (Nasdaq: MACK), a clinical-stage oncology company focused on biomarker-defined cancers, today announced its second quarter 2018 financial results for the period ended June 30, 2018.

"A cornerstone of Merrimack's approach to drug development is our commitment to test targeted therapies in biomarker-enriched patient populations, resulting in smaller, shorter and more personalized studies that lower development costs and accelerate the timeframe to clinically meaningful data. This quarter, we have continued to demonstrate prudent adherence to this clinical strategy," said Richard Peters, M.D., Ph.D., President and Chief Executive Officer. "Additionally, we are pleased to have strengthened our financial position with non-dilutive sources of capital, including an $18 million milestone announced today and the $15 million debt facility we closed in July, which we believe extend our cash runway into at least the first quarter of 2020 and position us to deliver on our corporate goals. Looking ahead, we anticipate significant progress across our pipeline, with two clinical readouts expected in the second half of 2018 from MM-121 in non-small cell lung cancer and MM-310 in solid tumors."

Key events from the second quarter and more recently include:

• Receipt of $18 million milestone payment from Shire, resulting from the sale of ONIVYDE in two additional major European countries;
• Closing in July of $25 million debt facility with Hercules Capital, $15 million of which was funded at closing, with eligibility for up to an additional aggregate of $10 million;
• Announcement of top-line results from the CARRIE study, a randomized Phase 2 trial of MM-141 in front-line metastatic pancreatic cancer, in which MM-141 was added to standard-of-care chemotherapy treatments and evaluated in patients screened for high serum levels of the insulin-like growth factor-1 (IGF-1). As MM-141 did not demonstrate a clinical benefit in the study, Merrimack will cease all of its development activities for MM-141; and
• Presentation of two posters at the 2018 American Society of Clinical Oncology (ASCO) Annual Meeting, held June 1-5, 2018 in Chicago, IL:
  • Clinical data from MM-121 (seribantumab) in a poster titled, "Evaluation of fixed-dose regimens of seribantumab in patients with solid tumors," containing an analysis of pharmacokinetic and safety data comparing different dosing regimens from previous Phase 1 and Phase 2 studies of MM-121 in solid tumors. Data presented support use of the dosing regimen currently being evaluated in Merrimack's two ongoing randomized Phase 2 studies of MM-121, SHERLOC in non-small cell lung cancer (NSCLC) and SHERBOC in HR+/HER2- metastatic breast cancer; and
  • A Trials-in-Progress poster for MM-310, Merrimack's antibody-directed nanotherapeutic (ADN) targeting the EphA2 receptor, titled, "A Phase 1 study evaluating the safety, pharmacology and preliminary activity of MM-310 in patients with solid tumors."

Upcoming Clinical Milestones

Merrimack anticipates the following upcoming clinical milestones:

• Top-line results in 2018 from the SHERLOC study, a randomized Phase 2 clinical trial evaluating MM-121, a fully human monoclonal antibody targeting the HER3 receptor, added to standard of care in patients with heregulin positive non-small cell lung cancer; and
• Safety data and maximum tolerated dose in 2018 from the Phase 1 clinical trial of MM-310, an antibody-directed nanotherapeutic targeting the EphA2 receptor, in patients with solid tumors.

Second Quarter 2018 Financial Results

The following summarizes Merrimack's financial results for the quarter ended June 30, 2018:

• Research and development expenses for the second quarter ended June 30, 2018 were $13.7 million, compared to $19.8 million for the comparable period of 2017. Research and development spending for the second quarter of 2018 was lower versus the comparable period in 2017 primarily due to Merrimack's refocused clinical and preclinical pipeline;
• General and administrative expenses for the second quarter ended June 30, 2018 were $3.5 million, compared to $14.8 million for the comparable period of 2017. General and administrative spending for the second quarter of 2018 was lower versus the comparable period in 2017 primarily due to a decrease in corporate expenses related to headcount levels following the asset sale to Ipsen;
• Net loss for the second quarter ended June 30, 2018 was $17.8 million, or $1.33 per share, compared to a net loss of $28.9 million, or $2.18 per share, for the comparable period of 2017; and
• As of June 30, 2018, Merrimack had 13.3 million shares of common stock, $0.01 par value per share, outstanding.

Financial Outlook

Merrimack believes that its cash, cash equivalents and marketable securities of $60.0 million as of June 30, 2018, in addition to $14.7 million in net borrowings from its July 2, 2018 loan and security agreement with Hercules Capital and the $18 million ONIVYDE milestone received from Shire, will be sufficient to fund its planned operations into at least the first quarter of 2020.

Merrimack remains eligible to receive additional milestone payments from Shire and Ipsen, resulting from the Company's asset sale to Ipsen in 2017:

• Merrimack is entitled to receive up to an additional $15 million in milestone payments from Shire, which are excluded from the Company's cash runway guidance until achieved, consisting of:
  • $5.0 million related to the sale of ONIVYDE in the first major non-European, non-Asian country; and
  • $10.0 million for the first patient dosed in a pivotal clinical trial in an indication other than pancreatic cancer.
• Merrimack is also entitled to receive up to an aggregate of $450 million in regulatory-based milestone payments from Ipsen, which Merrimack has said it expects to pass through to stockholders, net of any taxes owed and subject to there being sufficient surplus at that time, consisting of:
  • $225.0 million upon approval by the FDA of ONIVYDE for the first-line treatment of metastatic adenocarcinoma of the pancreas, subject to certain conditions;
  • $150.0 million upon approval by the FDA of ONIVYDE for the treatment of small cell lung cancer after failure of first-line chemotherapy; and
  • $75.0 million upon approval by the FDA of ONIVYDE for an additional indication unrelated to those described above.

About Merrimack

Merrimack is a biopharmaceutical company based in Cambridge, Massachusetts that is outthinking cancer to ensure that patients and their families live fulfilling lives. Its mission is to transform cancer care through the smart design and development of targeted solutions based on a deep understanding of cancer pathways and biological markers. All of Merrimack's development programs, including three clinical studies and six candidates in preclinical development, fit into its strategy of 1) understanding the biological problems it is trying to solve, 2) designing specific solutions and 3) developing those solutions for biomarker-selected patients. This three-pronged strategy seeks to ensure optimal patient outcomes. For more information, please visit Merrimack's website at www.merrimack.com.