• Expanded deal focuses on Synaffix’s GlycoConnect™ site-specific ADC bioconjugation technology and adds license options for six new programs to existing deal
  • Mersana currently developing two programs based on GlycoConnect™ site-specific ADC bioconjugation technology (XMT-1592 and XMT-1660)

AMSTERDAM, NETHERLANDS, November 30, 2021 — Synaffix B.V., a biotechnology company focused on commercializing its clinical-stage platform technology for the development of antibody-drug conjugates (ADCs) with best-in-class therapeutic index, today announces the expansion of its license agreement with 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.

Under the expanded license agreement, Mersana will expand its access to Synaffix’s GlycoConnect™ site-specific ADC bioconjugation technology for six additional ADC targets. The license rights granted to Mersana are tied to specific ADC targets to be selected and provide non-exclusive access to deploy GlycoConnect™ site-specific ADC bioconjugation technology against the specified targets. Under the expanded deal, Synaffix is eligible to receive upfront and milestone payments on a per-target basis with a total potential deal value exceeding $1 billion plus royalties. This builds on the long-term relationship between the two companies announced in 2019.

Anna Protopapas, President and Chief Executive Officer of Mersana Therapeutics, said:

“Our collaboration with Synaffix and use of the GlycoConnect™ site-specific ADC bioconjugation technology has yielded highly innovative ADC products with superior characteristics. Based on the data that we generated to date across multiple programs, we have gained the confidence to significantly expand our collaboration with Synaffix and elect GlycoConnect™ as our preferred site-specific ADC bioconjugation technology.”

Peter van de Sande, Chief Executive Officer of Synaffix, said:

“We are delighted to expand our collaboration with Mersana, a leader in ADC innovation, who will be utilizing our GlycoConnect™ platform to build out their pipeline with innovative ADC cancer therapeutics. We are honored to see the confidence that Mersana has placed in our platform, demonstrating once again the added value GlycoConnect™ can bring to innovative ADCs.”

Mersana will continue to be responsible for the research, development, manufacturing and commercialization of any resulting ADC products.

This licensing agreement expansion follows three recent ADC technology out-licensing agreements with Kyowa Kirin, a global specialty pharmaceutical company; ProfoundBio, an emerging oncology biotherapeutics company; and Innovent Biologics, a leading biopharmaceutical company developing innovative medicines for the treatment of major diseases. Other collaborators include ADC Therapeutics and Shanghai Miracogen. Twelve ADCs using Synaffix’s technology are currently in development of which three are in clinical development.

About Mersana Therapeutics

Mersana Therapeutics is a clinical-stage biopharmaceutical company using its differentiated and proprietary ADC platforms to rapidly develop novel ADCs with optimal efficacy, safety and tolerability to meaningfully improve the lives of people fighting cancer. Mersana’s lead product candidate, upifitamab rilsodotin (UpRi), is a Dolaflexin ADC targeting NaPi2b and is being studied in UPLIFT, a single-arm registration strategy in patients with platinum-resistant ovarian cancer, as well as in UPGRADE, a Phase 1 umbrella study in combination with other ovarian cancer therapies. XMT-1592, Mersana’s second ADC product candidate targeting NaPi2b-expressing tumors, was created using Mersana’s customizable and homogeneous Dolasynthen platform and is in the dose escalation portion of a Phase 1 proof-of-concept clinical study. The Company’s early-stage programs include XMT-1660, a Dolasynthen ADC targeting B7-H4, as well as XMT-2056, a STING-agonist ADC developed using the Company’s Immunosynthen platform and targeting a novel epitope of human epidermal growth factor receptor 2 (HER2). In addition, multiple partners are using Mersana’s Dolaflexin platform to advance their ADC pipelines. The Company routinely posts information that may be useful to investors on the “Investors and Media” section of our website at www.mersana.com.