On August 13, 2025 Mersana Therapeutics, Inc. (NASDAQ: MRSN), a clinical-stage biopharmaceutical company focused on the development of antibody-drug conjugates (ADCs) targeting cancers in areas of high unmet medical need, reported a business update and announced financial results for the second quarter ended June 30, 2025 (Press release, Mersana Therapeutics, AUG 13, 2025, View Source [SID1234655201]).
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"During the second quarter, we were excited to have Emi-Le clinical data presented in oral sessions at both ASCO (Free ASCO Whitepaper) 2025 and ESMO (Free ESMO Whitepaper) Breast Cancer 2025. These presentations highlighted Emi-Le’s encouraging clinical activity in patients with TNBC post-topo-1 treatment and those with adenoid cystic carcinoma type 1 (ACC-1)," said Martin Huber, M.D., President and Chief Executive Officer of Mersana Therapeutics. "Our team has continued to make important progress in recent months, as evidenced by the strong pace of enrollment in the two ongoing dose expansion cohorts in our Phase 1 clinical trial of Emi-Le. We look forward to reporting initial clinical data from these expansion cohorts later this year."
Emiltatug Ledadotin (Emi-Le; XMT-1660)
Mersana has continued to advance the development of Emi-Le, the company’s B7-H4-directed Dolasynthen ADC.
Medical Congress Presentations: During the second quarter of 2025, clinical data as of a March 8, 2025 data cut-off from dose escalation and backfill cohorts in the Phase 1 clinical trial of Emi-Le were included in oral presentations at the American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) 2025 Annual Meeting (ASCO 2025) in Chicago, IL and the European Society for Medical Oncology Breast Cancer 2025 Annual Congress (ESMO Breast Cancer 2025) in Munich, Germany. The ASCO (Free ASCO Whitepaper) 2025 presentation included data for patients across all enrolled tumor types, and the ESMO (Free ESMO Whitepaper) Breast Cancer 2025 presentation focused primarily on patients with post-topo-1 TNBC. These presentations can be accessed by visiting the Publications section of the Mersana website at www.mersana.com.
Expansion Update: Mersana continues to enroll patients with TNBC who have received one to four prior lines of therapy, including at least one topo-1 ADC. This stage of the trial is enrolling patients in two cohorts:
A "Dose A" cohort, in which patients are receiving 67.4 mg/m2 of Emi-Le every four weeks (Q4W), and
A "Dose B" cohort, in which patients are receiving 80 mg/m2 Q4W following a loading dose of 44.5 mg/m2 on days 1 and 8 of the first four-week cycle.
Collectively, more than 45 patients with TNBC have been enrolled across the two cohorts. Mersana plans to report initial clinical data from the expansion portion of its Phase 1 clinical trial in the second half of 2025.
XMT-2056
The dose escalation portion of Mersana’s Phase 1 clinical trial of XMT-2056, the company’s lead Immunosynthen ADC candidate targeting a novel HER2 epitope, is ongoing. Additionally, in July 2025, Mersana achieved a $15 million development milestone under its agreement with GSK plc, which has an exclusive global license option to co-develop and commercialize XMT-2056. Payment of the milestone is due in the third quarter of 2025. Mersana expects to present initial clinical pharmacodynamic STING activation data for XMT-2056 in the second half of 2025.
Collaborations
Mersana continues to support its collaborations with both Johnson & Johnson (Dolasynthen research collaboration) and Merck KGaA, Darmstadt, Germany (Immunosynthen research collaboration).
Reverse Stock Split
A 1-for-25 reverse stock split of the issued and outstanding shares of Mersana’s common stock (the Reverse Stock Split) became effective at 5:00 p.m. ET on July 25, 2025, and the company’s common stock began trading on a split-adjusted basis on July 28, 2025. The Reverse Stock Split reduced the number of outstanding shares of the company’s common stock from approximately 124.8 million shares to approximately 5.0 million shares. The shares outstanding and per share amounts below have been adjusted to reflect the Reverse Stock Split.
On August 11, 2025, the company received formal notification from The Nasdaq Stock Market, LLC (Nasdaq) confirming that the company has regained compliance with Nasdaq’s minimum bid price requirement. The regaining of compliance is a result of the closing bid price per share of the company’s common stock being at least $1.00 for a minimum of 10 consecutive business days prior to the August 25, 2025 compliance deadline, as described in the initial notice from Nasdaq to the company dated February 25, 2025.
Second Quarter 2025 Financial Results and Recent Updates
Net cash used in operating activities for the second quarter of 2025 was $22.6 million, which included $2.4 million in severance-related payments.
Cash and cash equivalents as of June 30, 2025 were $77.0 million.
In July 2025, Mersana made a payment of approximately $17.9 million to satisfy in full its indebtedness and obligations under the company’s previous loan and security agreement. The company continues to expect that its capital resources will be sufficient to support its current operating plan commitments into mid-2026.
Collaboration revenue for the second quarter of 2025 was $3.1 million, compared to $2.3 million for the same period in 2024. The year-over-year change was primarily related to increased revenue recognized under the company’s collaboration and license agreements with Johnson & Johnson and Merck KGaA, Darmstadt, Germany, partially offset by reduced revenue recognized under its agreement with GSK.
Research and development (R&D) expense for the second quarter of 2025 was $16.2 million, compared to $17.2 million for the same period in 2024. Included in the second quarter of 2025 R&D expense was $0.9 million in non-cash stock-based compensation expense. The year-over-year change in R&D expense was primarily related to lower headcount and related employee compensation costs, partially offset by an increase in costs related to Emi-Le and XMT- 2056 clinical development activities and manufacturing activities associated with the company’s collaborations.
General and administrative (G&A) expense for the second quarter of 2025 was $7.4 million, compared to $10.5 million during the same period in 2024. Included in the second quarter of 2025 G&A expense was $1.1 million in non-cash stock-based compensation expenses. The year-over-year change in G&A expense was primarily related to lower headcount and related employee compensation costs and a reduction in consulting and professional services fees.
Mersana incurred $3.9 million in restructuring expenses for the second quarter of 2025 related primarily to severance and benefit payments, outplacement services and related expenses.
Net loss for the second quarter of 2025 was $24.3 million, or $4.87 per share, compared to a net loss of $24.3 million, or $4.96 per share, for the same period in 2024.
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 second quarter of 2025. 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.