Mersana Therapeutics Presents New Preclinical Data from Immunosynthen Platform at the Society for Immunotherapy of Cancer (SITC) 34th Annual Meeting

Cambridge, Massachusetts, UNITED STATES

CAMBRIDGE, Mass., Nov. 08, 2019 (GLOBE NEWSWIRE) -- Mersana Therapeutics, Inc. (NASDAQ:MRSN), a clinical-stage biopharmaceutical company focused on discovering and developing a pipeline of antibody drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, today presented new preclinical data from its novel Immunosynthen platform at the 34th Annual Meeting of the Society for Immunotherapy of Cancer (SITC) taking place from November 6 - 10, 2019, in National Harbor, MD.

The poster describes the results of studies in which Mersana utilized its expertise to generate novel ADCs providing targeted delivery of a STimulator of Interferon Genes (STING) agonist and investigated their activity and mechanism of action in vitro and in vivo. STING has emerged as an innate immune pathway capable of inducing anti-tumor immune activity.

“We are excited by these preclinical data which demonstrate that STING ADCs activate a local immune response leading to tumor regression while limiting systemic toxicities,” said Tim Lowinger, Ph.D., CSTO of Mersana Therapeutics. “We look forward to selecting our lead STING ADC candidate and advancing it into clinical studies.”

The data show that STING ADCs achieved greater than 100-fold higher potency than the corresponding free agonist in in vitro assays. Similarly, in tumor cell/PBMC co-cultures the targeted STING ADC induced greater than 100-fold higher potency of tumor cell-killing by PBMCs compared to free agonist, demonstrating the benefits of the platform. In vivo data show potent antitumor activity, with a single administration of the targeted STING ADC inducing sustained tumor regressions. At the dose level that regressed tumors, the targeted STING ADCs showed significantly lower induction of serum cytokines relative to a systemically administered STING agonist despite maintaining extended plasma exposure.

“The opportunity to harness the innate immune system to attack tumors represents the next frontier in immuno-oncology,” said Anna Protopapas, President and CEO of Mersana Therapeutics. “These exciting preclinical data demonstrate Mersana’s strong expertise and commitment to developing innovative ADC therapies for patients living with cancer.”

Details of the presentation are as follows:

Poster Title: “Tumor Targeting of a STING Agonist with an Antibody-Drug Conjugate Elicits Potent Anti-Tumor Immune Responses”
Date: Friday, November 8, 2019
Time: 8:00 a.m. ET – 8:00 p.m. ET
Category: Immuno-conjugates and chimeric molecules
Poster: # P695

About Mersana Therapeutics

Mersana Therapeutics is a clinical-stage biopharmaceutical company using its differentiated and proprietary ADC platforms to develop highly targeted drugs with increased tolerability and expanded opportunities to deliver meaningful clinical benefit to cancer patients. Mersana’s lead product candidate, XMT-1536, is in a Phase 1 clinical trial in patients with tumors expressing NaPi2b, including ovarian cancer and NSCLC adenocarcinoma. In addition, multiple partners are using Mersana’s platform to advance their ADC pipelines.

Forward-Looking Statements

This press release contains “forward-looking” statements within the meaning of federal securities laws.  These forward-looking statements are not statements of historical facts and are based on management’s beliefs and assumptions and on information currently available to management. Forward-looking statements include information concerning the Company’s business strategy and the design, progression and timing of its clinical trials. Forward-looking statements generally can be identified by terms such as “anticipates,” “believes,” “could,” “seeks,” “estimates,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would” or similar expressions and the negatives of those terms. Forward-looking statements represent management’s beliefs and assumptions only as of the date of this press release. The Company’s operations involve risks and uncertainties, many of which are outside its control, and any one of which, or combination of which, could materially affect its results of operations and whether the forward-looking statements ultimately prove to be correct.  Factors that may materially affect the Company’s results of operations and whether these forward-looking statements prove to be correct include, among other things, that preclinical testing may not be predictive of the results or success of ongoing or later preclinical or clinical trials, that the development and testing of the Company’s product candidates and new platforms will take longer and/or cost more than planned and that the identification of new product candidates will take longer than planned, as well as those listed in the Company’s Annual Report on Form 10-K filed on March 8, 2019, with the Securities and Exchange Commission (“SEC”) and subsequent SEC filings. Except as required by law, the Company assumes no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.


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