MRSN Mersana Therapeutics Inc

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 UPLIFT, a single-arm registration strategy to evaluate the safety and efficacy of upifitamab rilsodotin (UpRi, XMT-1536) in patients with platinum-resistant ovarian cancer who have received up to four lines of therapy.

“UpRi has demonstrated clinically meaningful activity, a biomarker-response relationship and a differentiated tolerability profile without severe neutropenia, peripheral neuropathy or ocular toxicity in heavily pretreated ovarian cancer patients who have limited options and poor prognosis. The UPLIFT strategy is critical to bringing this promising agent to patients waiting for new therapies,” said Anna Protopapas, President and Chief Executive Officer of Mersana Therapeutics.

UPLIFT will evaluate the safety and efficacy of UpRi in patients with platinum-resistant ovarian cancer who have received up to four lines of therapy. Consistent with the bevacizumab label, patients previously treated with three or four lines of therapy may enroll without regard to prior bevacizumab treatment. There is no exclusion for patients with baseline peripheral neuropathy. Patients may enroll without regard to NaPi2b expression; however, the role of the biomarker will be evaluated. The primary endpoint will be the objective response rate (ORR) in the high NaPi2b population and the secondary endpoints will be the ORR regardless of NaPi2b expression, as well as duration of response and safety.

“We believe this study design, which is an amendment to the ongoing Phase 1 expansion study, allows for significant operational efficiencies and leverages our current momentum in patient enrollment. The study design also allows us the opportunity to fully evaluate the role of the biomarker with endpoints in both the high NaPi2b and overall populations. We are excited to open this cohort to this heavily pretreated patient population with few options,” said Arvin Yang, M.D., Ph.D., Senior Vice President and Chief Medical Officer of Mersana Therapeutics.

The single-arm registration strategy is an amendment to the ongoing multinational, multi-center, open label study protocol, and the Company expects to enroll approximately 100 patients with high NaPi2b expression and up to 180 patients overall.

About Mersana TherapeuticsMersana 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 the expansion portion of a Phase 1 proof-of-concept clinical study in patients with 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 XMT-1660, a Dolasynthen ADC targeting B7-H4, as well as XMT-2056, 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.

Forward-Looking StatementsThis 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, the ability of the single-arm UPLIFT cohort to enable registration, and expectations regarding future clinical trial results based on data achieved to date, and the sufficiency of the Company’s cash on hand. Forward-looking statements generally can be identified by terms such as “aims,” “anticipates,” “believes,” “contemplates,” “continues,” “could,” “designed to,” “efforts,” “estimates,” “expects,” “goal,” “intends,” “may,” “on track,” “opportunity,” “plans,” “poised for,” “possible,” “potential,” “predicts,” “projects,” “promises to be,” “seeks,” “should,” “strategy,” “target,” “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 or early clinical results may not be predictive of the results or success of ongoing or later preclinical or clinical studies, that the identification, development and testing of the Company’s product candidates and new platforms will take longer and/or cost more than planned, and that our clinical studies may not be initiated or completed on schedule, if at all, as well as those listed in the Company’s Annual Report on Form 10-K filed on February 26, 2021, with the Securities and Exchange Commission (“SEC”), and subsequent SEC filings. In addition, while we expect that the COVID-19 pandemic might adversely affect the Company’s preclinical and clinical development efforts, business operations and financial results, the extent of the impact on the Company’s operations and the value of and market for the Company’s common stock will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, physical distancing and business closure requirements in the U.S. and in other countries, and the effectiveness of actions taken globally to contain and treat the disease. 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.

Contact:Investor & Media ContactSarah Carmody, 617-844-8577scarmody@mersana.com