Mersana Therapeutics Announces Research Collaboration and

  • Collaboration focuses on discovery of novel STING agonist ADCs for up to two targets leveraging Mersana’s proprietary immunostimulant platform
  • Mersana to receive $30 million upfront payment, up to $800 million in development, regulatory and commercial milestones, and tiered royalties down to low double-digit percentages on net sales
  • Mersana’s Third Significant Collaboration Agreement in 2022 Reflects Its Growing Role as ADC’s Partner of Choice

CAMBRIDGE, Mass., Dec. 22, 2022 (GLOBE NEWSWIRE) — Mersana Therapeutics, Inc. (NASDAQ: MRSN), a clinical-stage biopharmaceutical company focused on the discovery and development of a pipeline of antibody-drug conjugates (ADCs) targeting cancers in areas with high unmet medical needs, today announced a research collaboration and commercial licensing agreement with a subsidiary of Merck KGaA, Darmstadt, Germany, to discover new Immunosynthen ADCs directed against up to two targets. Immunosynthen, Mersana’s proprietary STING agonist ADC platform, is designed to generate systemically delivered ADCs that locally activate STING signaling in both tumor-resident immune cells and antigen-expressing tumor cells, unlocking the antitumor potential of innate immune stimulation.

“Building on our deep expertise in the ADC space, we are focused on cutting-edge next-generation ADC drug discovery,” said Paul Lyne, Unit Head of Research, Oncology, Merck KGaA, Darmstadt, Germany. “An approach that can directly target the tumor microenvironment with an immunomodulatory ADC has the potential to bring the benefits of this immunotherapy to a larger group of patients. This collaboration with Mersana to design new immunostimulatory ADCs that can harness the potential of the STING pathway is an ideal complement to our innovation in this area.”

The STING pathway is a critical means of generating innate immune responses that can lead to antitumor activity and immunological memory. Mersana generated preclinical data demonstrating the ability of Immunosynthen to enable highly targeted STING activation within both tumor cells and tumor-resident myeloid cells, while avoiding undesirable systemic effects.

“We are delighted to partner with Merck KGaA, Darmstadt, Germany in a collaboration designed to extend the reach of our Immunosynthen platform and advance new product candidates with the potential to benefit patients,” said Anna Protopapas, President and Chief Executive Officer of Mersana Therapeutics. “With three significant new collaborations signed in 2022 alone, we are demonstrating Mersana’s growing role as a reference partner in the ADC field”.

Under the terms of the agreement, Mersana will develop new ADC product candidates against up to two targets using its Immunosynthen platform to conjugate proprietary antibodies from Merck KGaA, Darmstadt, Germany. Mersana will be responsible for certain discovery activities as well as limited preclinical manufacturing and supply obligations, which will be reimbursed by Merck KGaA, Darmstadt, Germany. Merck KGaA, Darmstadt, Germany will be solely responsible in vitro and live characterization, other preclinical work, and all clinical development and potential commercialization activities related to any resulting product candidates.

Mersana will receive an upfront payment of $30 million. Mersana is also eligible for reimbursement of certain costs, up to $800 million in potential regulatory, development and commercial milestone payments and royalties up to the low double-digit percentages of worldwide net sales of any approved ADC developed under of the agreement.

About Mersana Therapeutics
Mersana Therapeutics is a clinical-stage biopharmaceutical company using its proprietary, differentiated ADC platforms to rapidly develop new ADCs with optimal efficacy, safety and tolerability to significantly improve the lives of people battling cancer. Mersana’s lead product candidate, upifitamab rilsodotin (UpRi), is a Dolaflexin ADC targeting NaPi2b that is being studied in UPLIFT, a single-arm enrollment study in patients with platinum-resistant ovarian cancer; UPGRADE-A, a Phase 1/2 clinical study evaluating UpRi in combination with carboplatin; and UP-NEXT, a Phase 3 clinical study of UpRi as maintenance monotherapy following platinum doublet treatment in recurrent platinum-sensitive ovarian cancer. Mersana is also promoting XMT-1660, a Dolasynthen ADC targeting B7-H4, and XMT-2056, an Immunosynthen ADC targeting a novel human epidermal growth factor receptor 2 (HER2) epitope, among other prior-phase assets . Additionally, several partners use Mersana’s platforms to advance their ADC pipelines. Mersana regularly publishes information that may be useful to investors in the Investors & Media section of its website at

Forward-Looking Statements
This press release contains “forward-looking” statements and information within the meaning of the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “objectives”, “anticipates”, “believes”, “may”, “estimates”, ” expects”, “forecasts”, “goals”, “intends”, “may”, “plans”, “possible”, “potential”, “seeks”, “will” and variations of these words or similar expressions, even if not all forward-looking statements contain these words. Forward-looking statements in this press release include, but are not limited to, those relating to Mersana’s cooperation with Merck KGaA, Darmstadt, Germany; the development and potential commercialization of product candidates through this collaboration; the obligations of the parties deriving from the collaboration and license agreement; the therapeutic potential of Mersana’s product candidates, including those based on its Immunosynthen platform; the expected receipt of an advance payment from Merck KGaA, Darmstadt, Germany; and Mersana’s potential to receive future payments and royalties under its partnership with Merck KGaA, Darmstadt, Germany. Mersana may not actually achieve the plans, intentions or expectations disclosed in these forward-looking statements and you should not place undue reliance on these forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in these forward-looking statements due to various factors, including, among other things, uncertainties inherent in research and development, the initiation of clinical trials and the clinical development of product candidates; the risk that Mersana does not realize the expected benefits from its platforms, technologies and collaborations; the risk that the results of preclinical studies are predictive of the results of clinical studies; risks to the ability of Mersana and its Collaboration Partners to meet other anticipated deadlines and milestones, whether presented by the ongoing COVID-19 pandemic or otherwise; and other important factors, any of which could cause Mersana’s actual results to differ from those contained in the forward-looking statements, which are described in more detail in the section entitled “Risk Factors” in Mersana’s Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission (“SEC”) on November 7, 2022, as well as in other filings that Mersana may file with the SEC in the future. Any forward-looking statements contained in this press release speak only as of the date hereof, and Mersana expressly disclaims any obligation to update any forward-looking statements contained herein, whether due to new information, future events, changed circumstances, or otherwise, except as otherwise required by law.

Jason Fredette
[email protected]

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