CAMBRIDGE, Mass. and BANNOCKBURN, Ill., May 19, 2016 /PRNewswire/ -- Merrimack Pharmaceuticals, Inc. (Nasdaq: MACK) and Baxalta Incorporated (NYSE: BXLT) today jointly announced the initiation of a Phase 1 clinical study of Merrimack's oligoclonal EGFR (epidermal growth factor receptor) inhibitor, MM-151, in combination with ONIVYDE® (irinotecan liposome injection) plus fluorouracil (5-FU) and leucovorin in patients with RAS wild-type metastatic colorectal cancer. Data from a prior Phase 1 study of MM-151 supports further clinical evaluation of the investigational therapy in patients with metastatic colorectal cancer. The initiation of this study advances the development path for ONIVYDE.

"Metastatic colorectal cancer remains a deadly disease with only 11% of patients surviving five years or longer," said Dr. Emily Chan, Principal Investigator, Associate Professor of Medicine and GI Medical Oncologist, Vanderbilt-Ingram Cancer Center. "As our understanding of the dynamics of cancer cells increases, we are able to develop and explore novel targeted combination therapies to combat this deadly disease. This study is a significant step forward toward addressing this unmet medical need, and providing a potential new treatment option to patients facing this deadly disease."

This Phase 1 study will assess the safety and tolerability of the combination of MM-151, a novel antibody mixture of three human antibodies designed to target EGFR which promotes tumor growth, and ONIVYDE, also known as MM-398 or "nal-IRI," plus 5-FU and leucovorin as first or second-line treatment in patients with RAS wild-type metastatic colorectal cancer.

"We are excited to initiate this Phase 1 clinical study, which will enable us to evaluate MM-151 in combination with the ONIVYDE regimen," said J. Marc Pipas, M.D., Medical Director at Merrimack. "Preclinically, MM-151 has shown superior inhibition of the EGFR pathway compared to FDA approved EGFR inhibitors. Combining MM-151 with the ONIVYDE regimen represents an exciting opportunity to investigate a potential new treatment regimen for patients with metastatic colorectal cancer."

The trial will determine the side effect profile of MM-151 in combination with ONIVYDE plus 5-FU and leucovorin and recommended dose for subsequent trials with this combination. Eligible patients for the study must have metastatic disease, have had no prior exposure to irinotecan or an EGFR inhibitor, and have received no more than one prior line of treatment for metastatic disease. Merrimack plans to conduct the study at multiple sites in the United States. Merrimack will be solely responsible for the funding and execution of the Phase 1 study. For more information, please visit www.clinicaltrials.gov.

Merrimack and Baxalta have entered into an exclusive licensing agreement to develop and commercialize ONIVYDE outside of the United States. PharmaEngine, Inc. (Taipei, Taiwan) holds the rights to commercialize ONIVYDE in Taiwan and received the Taiwan FDA approval of ONIVYDE on October 22, 2015.

About MM-151

MM-151 is Merrimack's wholly owned oligoclonal therapeutic mixture consisting of three fully-human monoclonal antibodies designed to bind and inhibit signaling of the epidermal growth factor receptor (EGFR). EGFR-mediated signaling promotes the growth and survival of cancer cells and has long been recognized as an important drug target in several types of cancer, including colon, lung, breast, pancreatic, and head and neck cancers. MM-151 has previously been tested in a Phase 1 dose-escalation clinical trial in patients with advanced solid tumors.

About ONIVYDE® [pronounced \ 'on - ih - vide \]

ONIVYDE® (irinotecan liposome injection), also known as MM-398 or "nal-IRI," is a novel encapsulation of irinotecan in a liposomal formulation. The activated form of irinotecan is SN-38, which functions by inhibiting topoisomerase I (an essential enzyme involved in DNA transcription and replication) and promoting cell death. ONIVYDE was approved by the U.S. Food and Drug Administration in combination with fluorouracil and leucovorin for the treatment of patients with metastatic adenocarcinoma of the pancreas after disease progression following gemcitabine-based therapy. For full prescribing information, including Boxed WARNING, please visit www.ONIVYDE.com.

About Merrimack

Merrimack is a fully integrated biopharmaceutical company that views cancer as a complex engineering challenge. Through systems biology, which brings together the fields of biology, computing and engineering, Merrimack aims to decrease uncertainty in drug development and clinical validation, and move discovery efforts beyond trial and error. Such an approach has the potential to make individualized treatment of patients a reality. Merrimack's first commercial product, ONIVYDE® (irinotecan liposome injection), was approved by the U.S. FDA in October 2015. With four additional candidates in clinical studies, several in preclinical development and multiple biomarkers designed to support patient selection, Merrimack is building one of the most robust oncology pipelines in the industry. For more information, please visit Merrimack's website at www.merrimack.com or connect on Twitter at @MerrimackPharma.

About Baxalta Incorporated

Baxalta Incorporated (NYSE: BXLT) is a $6 billion global biopharmaceutical leader developing, manufacturing and commercializing therapies for orphan diseases and underserved conditions in hematology, oncology and immunology. Driven by passion to make a meaningful impact on patients' lives, Baxalta's broad and diverse pipeline includes biologics with novel mechanisms and advanced technology platforms such as gene therapy. The Baxalta Global Innovation and R&D Center is located in Cambridge, Massachusetts. Launched in 2015 following separation from Baxter International Inc., Baxalta's heritage in biopharmaceuticals spans decades. Baxalta's therapies are available in more than 100 countries and it has advanced biological manufacturing operations across 12 facilities, including state-of-the-art recombinant production and plasma fractionation. Headquartered in Northern Illinois, Baxalta employs 16,000 employees worldwide.

Forward-Looking Statements

To the extent that statements contained in this press release are not descriptions of historical facts, they are forward-looking statements reflecting the current beliefs and expectations of management made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements include any statements about Merrimack's strategy, future operations, future financial position, future revenues and future expectations and plans and prospects for Merrimack, and any other statements containing the words "anticipate," "believe," "estimate," "expect," "intend," "may," "plan," "predict," "project," "target," "potential," "will," "would," "could," "should," "continue," and similar expressions. In this press release, Merrimack's forward-looking statements include, among others, statements about the potential effectiveness and safety profile of MM-151 in combination with the ONIVYDE regimen and Merrimack's ability to translate clinical data into future clinical success. Such forward-looking statements involve substantial risks and uncertainties that could cause Merrimack's clinical development programs, future results, performance or achievements to differ significantly from those expressed or implied by the forward-looking statements. Such risks and uncertainties include, among others, the uncertainties inherent in the initiation of future clinical trials, availability of data from ongoing clinical trials, expectations for regulatory approvals, development progress of Merrimack's companion diagnostics, availability of funding sufficient for Merrimack's foreseeable and unforeseeable operating expenses and capital expenditure requirements, and other matters that could affect the availability or commercial potential of Merrimack's products, product candidates or companion diagnostics. Merrimack undertakes no obligation to update or revise any forward-looking statements. Forward-looking statements should not be relied upon as representing Merrimack's views as of any date subsequent to the date hereof. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to Merrimack's business in general, see the "Risk Factors" section of Merrimack's Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on February 26, 2016 and other reports Merrimack files with the SEC.

CONTACTS:
Media Contact:
Marianne McMorrow
774-776-1478
mmcmorrow@merrimack.com

Investor Contact:
Geoffrey Grande, CFA
617-441-7602
ggrande@merrimack.com

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SOURCE Merrimack Pharmaceuticals, Inc.