Mersana Therapeutics, Inc.

Good morning, and welcome to Mursana Therapeutics' first quarter 2022 conference call and webcast. Currently, all participants are in a listen-only mode. There will be a question-and-answer session at the end of this call. I would now like to turn the call over to Jason Ferdet, Senior Vice President, Investor Relations and Corporate Communications. Please proceed.

Good morning, everyone. Before we begin, I'd like to mention that our call will contain forward-looking statements within the meaning of the federal securities laws. These statements include, but are not limited to, those related to the company's business strategy, platform potential, clinical trial or preclinical study execution, and data releases, regulatory plans and objectives, commercial opportunities, and cash runway. Each of these forward-looking statements is subject to risks and uncertainties that could cause actual results to differ materially from those projected in such statements. These risks and uncertainties are discussed in the company's annual report on Form 10-K, filed with the Securities and Exchange Commission, or SEC, on February 28, 2022, and in subsequent SEC filings. These documents are available at sec.gov or on our website, mursana.com. except as required by law, we assume no obligation to update forward-looking statements publicly, even if new information becomes available in the future. With that, let me turn the call over to Ana Protopapas, Marsana's President and Chief Executive Officer.

Good morning, everyone, and welcome to our first quarter 2022 conference call. Joining me today with prepared remarks are our Chief Medical Officer, Arvind Yang, our Chief Science and Technology Officer, Tim Loinger, and Chief Financial Officer, Brian Descheidner. I'm also joined by certain other members of management who will be available to answer questions. Before I start, I would like to officially welcome to Mursana our new Senior VP of Investor Relations and Corporate Communications, Jason Fredette. We are excited to have him on board. 2022 is shaping up to be an incredibly exciting year as we continue to advance UPRI, prepare to bring two exciting new candidates into the clinic, and execute on our partnering strategy as we position Mursana for multiple important data readouts in 2023. Let me start by describing the progress we have made. on our goal of establishing UPRI as a foundational medicine for patients with ovarian cancer. We believe the clinical data we've shared in the past has demonstrated UPRI's efficacy and important tolerability advantages, namely the lack of severe neutropenia, neuropathy, and ocular toxicity that has been reported with other ATCs. Our current slate of trials, Uplift, Upnext, and Upgrade, have the potential to further validate this profile while also generating data across a broad range of ovarian cancer settings in an expeditious and capital-efficient manner. Uplift, a single arm registration trial in platinum-resistant ovarian cancer, is on track to complete enrollment in the third quarter of this year, positioning us for a 2023 readout and potential BLA filing. As Arvind will discuss in further detail, we are pleased to have been selected for an oral presentation at the Society of Cardiological Oncology, or SGO, to share additional analysis supporting our dose selection for uplift. Up next is our phase three trial of upper immunotherapy maintenance in NAPI to be high recurrent platinum sensitive ovarian cancer, which is an even larger patient population with significant unmet need. Up next has the potential to serve as a post-approval confirmatory trial in the U.S., support global registrations, and position UBRI as the first ADC in the platinum-sensitive space. An upgrade is our Phase I-II umbrella combination trial in early-aligned platinum-sensitive patients. Initially, we're evaluating the combination of operine with carboplatin, followed by continuation of operine monotherapy. We believe the preliminary dose escalation data planned for late this year will provide valuable insights into operine safety and tolerability in a combination setting, which could support our plans to expand into earlier lines of therapy. Beyond UPRI, we're advancing a pipeline in a thoughtful and capital-efficient manner, with 1660 and 2056 being our primary focus. Both of these candidates are on track to moving to the clinic in mid-2022. XMT1660 is our dollar synth and ADC directed at B7H4. Preclinically, we have generated compelling efficacy data demonstrating 1660s potential in B7 H4 expressing tumors of high unmet need, including breast, endometrial, and ovarian cancer. These will be primary indications of focus as we move into phase one. XMT 2056 is expected to be the second addition to our clinical pipeline this year, and our first immunosynth and sting agonist ADC to enter the clinic. It targets HER2, a validated target broadly expressed in a range of solid tumors, including breast, gastric, and non-small cell lung cancer. We have generated a robust preclinical data set demonstrating 2056 potential to create a pipeline in a product with a single agent activity in both high and low HER2 expressing models. Given that 2056 targets a novel epitope of HER2, we believe it has the potential to be synergistic with other HER2 agents, including those that have become standard of care in breast cancer and newer agents like in HER2. Additionally, we have seen its potential to work in combination with checkpoint inhibitors in preclinical models. Now, as many of you know, we also have been evaluating another NAPI-2B targeted ATC, XMT1592, as a second shot on goal in non-small cell lung cancer. Given the lower prevalence of the NAPI-2B biomarker in lung, the increasingly competitive nature of this indication, our commitment to remain financially disciplined, and the substantial opportunities we see ahead for uproot XMT 1660 and XMT 2056, we have decided to discontinue development of XMT 1592. In addition, we are deferring certain investments in our preclinical pipeline, including two of our earliest stage candidates, XMT 2068 and 2175, to focus our resources on Mursana's clinical pipeline. Our success with APRI, XMT1660, and 2056 has positioned us to have three candidates enabled by all three of our platforms, Dolaflexin, Dolasynthin, and Immunosynthin, in active clinical development this year. We view our platforms as capital-efficient product engines to fuel our own pipeline and to position Mursana as the ADC partner of choice at this time. when there is a surge of interest in the field. This in turn provides the opportunity to expand Mursana's reach and its ability to address patient needs while also bringing us non-diluted capital that can be redeployed in the business. And so we are off to a strong start in 2022 as we lay the foundation for what we hope will be a BLA filing and approval of UPRI in the not too distant future. Important initial clinical data for 1660 and 2056 and additional potential value creating partnerships. We are excited by the opportunities that lie ahead and will remain steadfastly focused on building value for patients who are waiting for new treatment options. With that, I would like to turn the call over to Arvind to delve deeper into UPRI and discuss our recent data at SGO.