Mersana Therapeutics, Inc.

Good morning and welcome to Mursana Therapeutics' third quarter 2024 conference call. Currently, all participants are in listen-only mode. There will be a question and answer session at the end of this call. Should you need assistance, please signal a conference specialist by pressing star then zero on your telephone keypad. Please note this event is being recorded. I would now like to turn the conference over to Jason Fredette, Senior Vice President, Investor Relations, and corporate communications. Please proceed.

Thank you, operator, and good morning, everyone. Before we begin, please note that this call will contain forward-looking statements within the meaning of federal securities laws. These statements may include, but are not limited to, those related to our platforms, product candidates, business strategy, clinical trial execution and data, business development efforts, 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 our quarterly report on Form 10Q, filed with the Securities and Exchange Commission on August 13, 2024, and in subsequent SEC filings. Our filings are available at sec.gov. and 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. On today's call, we have Mursana's Chief Executive Officer, Dr. Marty Huber, our Chief Development Officer, Mohan Bala, and our Chief Operating Officer and Chief Financial Officer, Brian Descheitner. With that, let's turn the call over to Marty to begin our discussion.

Thank you, Jason, and good morning, everyone. I'm pleased to report that Mursana made significant progress in the third quarter as we continued to dose escalate in our Phase I clinical trials of both XMT1660 and XMT2056. We also achieved multiple milestones in our research collaborations, and we maintained the strength of our balance sheet. These accomplishments position us well as we prepare to disclose initial XMT1660 clinical data at a company event by the end of this year. XMT1660 is Mursana's ADC candidate targeting B7H4 that was developed using our Dolacynthin platform with site-specific bioconjugation and a drug-to-antibody ratio of 6. We believe it has the opportunity to differentiate within the broader ADC landscape in multiple ways. The dose escalation portion of our phase one clinical trial is ongoing, and we still have not established a maximum tolerated dose. We recently escalated to 115 milligrams per meter squared, or about 3.1 milligrams per kilogram, every four weeks. This is up from the 80 milligrams per meter squared dose we mentioned on our last conference call, and it's well beyond the highest doses we investigated with any of our prior ADCs. We believe our ability to reach this dosing level speaks both to dolusynthin's differentiated tolerability profile and to the limited expression of B7H4 in healthy tissue. In parallel with our dose escalation work, we are continuing to investigate more frequent dosing schedules for XMT1660, and we're working to refine our biomarker strategy to prepare for expansion and later stages of development. Let me turn the call over to Mohan Bala, our Chief Development Officer, to share a little more color on our enrollment in this trial and one of the indications we are focusing on.