On March 3, 2025 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, reported a business update and reported financial results for the fourth quarter and full year ended December 31, 2024 (Press release, Mersana Therapeutics, MAR 3, 2025, View Source [SID1234650836]).

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"We made significant progress advancing the clinical development of Emi-Le in 2024," said Martin Huber, M.D., President and Chief Executive Officer of Mersana Therapeutics. "These efforts enabled us to begin 2025 by announcing positive initial Phase 1 clinical data, the initiation of expansion and a Fast Track designation for HER2-negative breast cancer patients who have previously been treated with at least one topo-1 ADC. With promising monotherapy activity reported in patients across multiple tumors, including those with heavily pretreated triple-negative breast cancer, as well as a differentiated tolerability profile that may enable combination approaches, we believe Emi-Le offers us unique development opportunities that are unavailable to other B7-H4 ADCs."

Emiltatug Ledadotin (Emi-Le; XMT-1660)
In January 2025, Mersana announced positive initial Phase 1 clinical data for Emi-Le, the company’s lead Dolasynthen ADC candidate targeting B7-H4, from 130 patients who were enrolled in dose escalation and backfill cohorts as of a December 13, 2024 data cutoff. The company also announced that Emi-Le had received a second Fast Track designation from the U.S. Food and Drug Administration (FDA).

The expansion portion of the company’s Phase 1 clinical trial continues at a dose of 67.4 mg/m² administered every four weeks in patients with TNBC who had received one to four prior lines of therapy, including at least one topo-1 ADC. In parallel, the company continues to explore higher doses in dose escalation and backfill cohorts to identify a second dose for expansion.

In 2025, Mersana plans to initiate expansion enrollment at a second dose in patients with TNBC who have received one to four prior lines of treatment, including at least one prior topo-1 ADC. The company also plans to present additional Phase 1 clinical data from dose escalation and backfill cohorts in 2025.

XMT-2056
Mersana has continued to advance the dose escalation portion of its Phase 1 clinical trial of XMT-2056, the company’s lead Immunosynthen ADC candidate targeting a novel HER2 epitope. GSK plc has an exclusive global license option to co-develop and commercialize XMT-2056. Mersana plans to continue enrolling patients in dose escalation and expects to present initial clinical pharmacodynamic STING activation data for XMT-2056 in 2025.

Collaborations
Mersana continues to advance its collaborations with both Johnson & Johnson (Dolasynthen research collaboration) and Merck KGaA, Darmstadt, Germany (Immunosynthen research collaboration).

Fourth Quarter 2024 Financial Results

Cash, cash equivalents and marketable securities as of December 31, 2024 were $134.6 million. Mersana continues to expect that its capital resources will be sufficient to support its current operating plan commitments into 2026.
Net cash used in operating activities for the fourth quarter of 2024 was $19.3 million.
Collaboration revenue for the fourth quarter of 2024 was $16.4 million, compared to $10.7 million for the same period in 2023. The year-over-year change was primarily related to increased collaboration revenue recognized under Mersana’s collaboration and license agreements with Johnson & Johnson, Merck KGaA, Darmstadt, Germany and GSK.
Research and development (R&D) expenses for the fourth quarter of 2024 were $22.3 million, compared to $21.5 million for the same period in 2023. Included in the fourth quarter of 2024 R&D expenses were $1.7 million in non-cash stock-based compensation expenses. The year-over-year increase in R&D expenses was primarily related to increased costs associated with manufacturing and clinical development activities for Emi-Le and XMT-2056, primarily offset by reduced costs related to clinical development activities for UpRi, a discontinued ADC candidate.
General and administrative (G&A) expenses for the fourth quarter of 2024 were $8.9 million, compared to $10.1 million during the same period in 2023. Included in the fourth quarter of 2024 G&A expenses were $1.7 million in non-cash stock-based compensation expenses. The year-over-year decline in G&A expenses was primarily related to reduced employee compensation expense following the company’s 2023 restructuring and reduced consulting and professional services fees.
Net loss for the fourth quarter of 2024 was $14.1 million, or $0.11 per share, compared to a net loss of $19.5 million, or $0.16 per share, for the same period in 2023.
Full Year 2024 Financial Results

Net cash used in operating activities for full year 2024 was $82.3 million.
Collaboration revenue for full year 2024 was $40.5 million, compared to $36.9 million for 2023. The year-over-year increase was primarily related to incremental milestone payments associated with the company’s Johnson and Johnson collaboration and license agreement.

R&D expenses for full year 2024 were $73.0 million, compared to $148.3 million for the full year 2023. Included in 2024 R&D expenses were $8.9 million in non-cash stock-based compensation expenses. The decline in R&D expenses was primarily related to reduced costs associated with manufacturing and clinical development activities for UpRi, reduced employee compensation expenses following the company’s restructuring in 2023, and reduced consulting and professional services fees, partially offset by increased costs for clinical development activities for Emi-Le.
G&A expenses for full year 2024 were $40.8 million, compared to $59.5 million for the full year 2023. Included in 2024 G&A expenses were $7.6 million in non-cash stock-based compensation expenses. The year-over-year decline in G&A expenses was primarily related to reduced consulting and professional services fees and reduced employee compensation expense following the aforementioned restructuring.
Net loss for full year 2024 was $69.2 million, or $0.56 per share, compared to a net loss of $171.7 million, or $1.48 per share, for the full year 2023.

Conference Call Reminder

Mersana will host a conference call today at 8:00 a.m. ET to discuss business updates and its financial results for the fourth quarter and full year of 2024. To access the call, please dial 833-255-2826 (domestic) or 412-317-0689 (international). A live webcast of the presentation will be available on the Investors & Media section of the Mersana website at www.mersana.com, and a replay of the webcast will be available in the same location following the conference call for approximately 90 days.