CAMBRIDGE, MA, USA I May 14, 2020 I 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 announced the initiation of patient dosing in a Phase 1 dose escalation study evaluating XMT-1592, its Dolasynthen ADC targeting NaPi2b. XMT-1592 is the Company’s first clinical candidate created using its new customizable and homogenous Dolasynthen ADC platform.

“XMT-1592 has shown a differentiated preclinical profile, particularly in NSCLC where we saw a four-fold increase in efficacy over XMT-1536, consistent with increased exposure to the DolaLock payload in the tumor, and we look forward to working to validate the clinical differentiation of this candidate,” said Anna Protopapas, President and Chief Executive Officer of Mersana Therapeutics. “XMT-1592 also has the potential to further extend our leadership position in NaPi2b-expressing malignancies, and we are very pleased to have reached this important 2020 goal of advancing this promising ADC candidate into the clinic.”

This Phase 1, open-label, dose-escalation study is designed to determine the maximum tolerated dose (MTD) of XMT-1592 in patients with non-small cell lung cancer (NSCLC) adenocarcinoma and ovarian cancer. Upon completion of the dose-escalation portion of the study, the Company will determine the path forward to further assess the safety and activity of XMT-1592 in the expansion portion of the study.

About XMT-1592
XMT-1592 is an ADC targeting NaPi2b-expressing tumors. XMT-1592 was created with the Dolasynthen platform, retaining the Company’s proprietary NaPi2b antibody and auristatin DolaLock payload with controlled bystander effect plus the added benefits of site-specific conjugation, precise drug-to-antibody ratio, and even greater hydrophilicity for further enhanced drug-like properties and tumor exposure. In preclinical studies, Dolasynthen has shown four times greater efficacy in a patient-derived lung tumor model in comparison to Dolaflexin, a platform that has already shown success when targeted to NaPi2b.

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, XMT-1536, is in the expansion portion of a Phase 1 proof-of-concept clinical study in patients with ovarian cancer and NSCLC adenocarcinoma. 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 a B7-H4 targeting ADC, as well as a STING-agonist ADC developed using the Company’s Immunosynthen platform. In addition, multiple partners are using Mersana’s Dolaflexin platform to advance their ADC pipelines.

SOURCE: Mersana Therapeutics