Merrimack Pharmaceuticals to Present Clinical Data Across Oncology Pipeline at ASCO 2014

MM-121 Phase 2 Data and Biomarker Findings to be Presented in Platinum Resistant Ovarian Cancer, ER/PR+ Breast Cancer and Non-Small Cell Lung Cancer

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| Source: Merrimack Pharmaceuticals

CAMBRIDGE, Mass., May 22, 2014 (GLOBE NEWSWIRE) -- Merrimack Pharmaceuticals, Inc. (Nasdaq:MACK) today announced it will present clinical data on four novel antibody cancer therapeutics at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting, May 30-June 3, 2014 at McCormick Place in Chicago. These presentations showcase Merrimack's broad oncology pipeline.

"ASCO is an exciting opportunity for us to share the first Phase 2 clinical data from our systems biology-driven MM-121 program. We believe these data identify a biomarker-positive set of patients across multiple cancers who do not perform well on standard of care therapies but who may significantly benefit from co-administration of MM-121," said Gavin MacBeath, Ph.D., Co-Founder and Senior Vice President at Merrimack. "These data also increase our confidence in our ongoing Phase 2 study of MM-111 in gastric cancer, where we are now prospectively evaluating a biomarker-positive population based on these new insights into ErbB3 biology. We also look forward to sharing Phase 1 data from our MM-141 and MM-151 programs as we seek to advance these therapies to Phase 2 development, along with our targeted nanoliposome MM-302."

Merrimack's system biology platform integrates the fields of biology, computing and engineering to gain a more comprehensive understanding of the key drivers of tumor growth and survival and the best ways to counteract them therapeutically. These insights allow Merrimack to deploy proprietary antibody and nanoliposomal technologies to enable the precise targeting of cancers, based on signaling pathways and the tumor microenvironment.  

"We believe that our rigorous understanding of cancer biology will enable us to transform cancer care over time. Our systems biology approach, nanoliposomal and antibody technologies, and diagnostic capabilities have broad applications and offer opportunities for significant treatment advances for patients," said Robert Mulroy, President and Chief Executive Officer at Merrimack. "The presentations at ASCO, along with our recently reported positive data for MM-398 combination therapy in metastatic pancreatic cancer, highlight the progress we are making across our entire clinical pipeline."

Merrimack will present data on the following programs at ASCO 2014 (details and locations of each presentation are listed below):

MM-121: An antibody designed to target ErbB3, a critical node in the progression of multiple cancer indications

  • Data sets from three Phase 2 studies of MM-121 - in platinum resistant ovarian cancer, ER/PR+, HER2-negative breast cancer, and non-small cell lung cancer - will be presented, along with primary results from analyses of pre-specified biomarkers in each study. The results across these studies highlight a biomarker-positive patient population that responds poorly to standard of care therapies and may benefit from MM-121 co-therapy, further supporting ErbB3 as a therapeutic target. Data from the Phase 2 study of MM-121 in platinum-resistant ovarian cancer will be featured in a Poster Highlights Session. Results of a Phase 1 study of MM-121 in combination with cetuximab and irinotecan for the treatment of advanced cancers will also be presented. These studies were all completed in collaboration with Sanofi.

MM-151: A novel oligoclonal antibody combination designed to inhibit EGFR-driven tumor growth

  • Data from a Phase 1 study including safety, pharmacokinetic and preliminary clinical results of MM-151 in patients with refractory solid tumors are being presented for the first time and will be featured in a Poster Highlights Session. Included are data that highlight the clinical experience with MM-151 in colorectal cancer, the focus of a planned Phase 2 study.
  • MM-151's oligoclonal composition is designed to block tumor growth by inhibiting EGFR- signaling and engaging the immune system.

MM-111: The first clinical stage bispecific antibody targeting HER2 and ErbB3

  • The design of an ongoing Phase 2 study of MM-111 in patients with HER2-positive advanced gastroesophageal carcinomas, investigating heregulin as a predictive biomarker, will be presented.
  • Data from a Phase 1 multi-arm, dose escalation trial of MM-111 in combination with HER2-targeted therapies and chemotherapies will also be presented. MM-111 is designed to inhibit ErbB3 in HER2-overexpressing tumor cells, as co-activation of these two proteins has been associated with poor prognosis in a variety of cancer types.

MM-141: A tetravalent antibody inhibitor of cancer cell survival pathways

  • Data from the monotherapy portion of the Phase 1 multi-arm study will be presented for the first time detailing safety, tolerability, pharmacokinetic and pharmacodynamic properties of MM-141.
  • MM-141 is designed to inhibit tumor cell growth by co-targeting receptor complexes containing IGF-1R and ErbB3.

MM-121

Poster Highlights Session:

  • A phase 2 randomized open-label study of MM-121, a fully human monoclonal antibody targeting ErbB3, in combination with weekly paclitaxel versus weekly paclitaxel in patients with platinum resistant/refractory ovarian cancers (Abstract #5519)
    Session Title: Gynecologic Cancers
    Monday, June 2, 2014, Display and Networking: 8:00 AM-11:00 AM CT, Discussion: 11:30 AM-12:45 PM CT
    Display & Networking—E354b; Discussion—E354a

General Poster Session:

  • A randomized phase 2 trial of MM-121, a fully human monoclonal antibody targeting ErbB3, in combination with erlotinib in EGFR wild-type NSCLC patients (Abstract #8051)
    Session Title: Lung Cancer – Non-small Cell Metastatic
    Saturday, May 31, 2014, 1:15 PM-5:00 PM CT
    S Hall A
  • A phase 1 study of MM-121 (a fully human monoclonal antibody targeting the epidermal growth factor receptor family member ErbB3) in combination with cetuximab and irinotecan in patients with advanced cancers (Abstract #3076)
    Session Title: Developmental Therapeutics – Immunotherapy
    Sunday, June 1, 2014, 8:00 AM-11:45 AM CT
    S Hall A
  • A randomized, double-blind phase II trial of exemestane plus MM-121 (a monoclonal antibody targeting ErbB3) or placebo in postmenopausal women with locally advanced or metastatic ER+/PR+, HER2-negative breast cancer (Abstract #587)
    Session Title: Breast Cancer - HER2/ER
    Monday, June 2, 2014, 8:00 AM-11:45 AM CT
    S Hall A

MM-151

Poster Highlights Session:

  • Phase 1 trial of MM-151, a novel oligoclonal anti-EGFR antibody combination in patients with refractory solid tumors (Abstract #2518)
    Session Title: Developmental Therapeutics: Clinical Pharmacology and Experimental Therapeutics
    Friday, May 30, 2014, Display and Networking: 1:00 PM-4:00 PM CT, Discussion: 4:30 PM-5:45 PM CT
    Display & Networking – E354b; Discussion—E Arie Crown Theater

MM-111

General Poster Session:

  • Randomized open-label phase 2 study of MM-111 and paclitaxel (PTX) with trastuzumab (TRAS) in patients with HER2-expressing carcinomas of the distal esophagus, gastroesophageal (GE) junction, and stomach who have failed front-line metastatic or locally advanced therapy. (Abstract #TPS4148)
    Session Title: Gastrointestinal (Noncolorectal) Cancer
    Saturday, May 31, 2014, 8:00 AM-11:45 AM CT
    S Hall A
  • A phase 1 study of MM-111, a bispecific HER2/HER3 antibody fusion protein, combined with multiple treatment regimens in patients with advanced HER2-positive solid tumors (Abstract #651)
    Session Title: Breast Cancer – HER2/ER
    Monday, June 2, 2014, 8:00 AM-11:45 AM CT
    S Hall A

MM-141

General Poster Session:

  • First-in-human study of MM-141: A novel tetravalent monoclonal antibody targeting IGF-1R and ErbB3 (Abstract #3068)
    Session Title: Developmental Therapeutics – Immunotherapy
    Sunday, June 1, 2014, 8:00 AM-11:45 AM CT
    S Hall A

About Merrimack

Merrimack is a biopharmaceutical company discovering, developing and preparing to commercialize innovative medicines paired with companion diagnostics for the treatment of cancer. Merrimack seeks to gain a deeper understanding of underlying cancer biology through its systems biology-based approach and develop new insights, therapeutics and diagnostics to improve outcomes for cancer patients. Merrimack currently has six oncology therapeutics in clinical development and three additional candidates in late stage preclinical development. For more information, please visit Merrimack's website at www.merrimackpharma.com.

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 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 statements about the potential effectiveness and tolerability of its investigational therapeutics in certain patient populations or subpopulations, its ability to develop a predictive diagnostic and its 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 and other matters that could affect the availability or commercial potential of Merrimack's drug 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 Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (SEC) on May 6, 2014 and other reports Merrimack files with the SEC.

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Merrimack
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