FDA Events for Mersana Therapeutics (MRSN)
This section highlights FDA-related milestones and regulatory updates for drugs developed by Mersana Therapeutics (MRSN).
Over the past two years, Mersana Therapeutics has reported clinical trial outcomes, regulatory submissions, approvals, and other FDA events for drugs and therapies such as
XMT-1660. For definitions of regulatory abbreviations such as NDA, BLA, or PDUFA, see the event status legend.
XMT-1660 - FDA Regulatory Timeline and Events
XMT-1660 is a drug developed by Mersana Therapeutics for the following indication: High unmet need tumors such as breast, endometrial and ovarian.
This drug is under review by the U.S. Food and Drug Administration (FDA).
Below is a timeline of key regulatory milestones for this therapy.
- Drug:
- XMT-1660
- Announced Date:
- June 2, 2025
- Indication:
- High unmet need tumors such as breast, endometrial and ovarian
Announcement
Mersana Therapeutics, announced additional interim Phase 1 clinical data for emiltatug ledadotin (Emi-Le; XMT-1660), the company's B7-H4-directed Dolasynthen ADC.
AI Summary
Mersana Therapeutics recently announced additional interim Phase 1 clinical data for its investigational agent emiltatug ledadotin (Emi-Le; XMT-1660), a B7-H4-directed Dolasynthen ADC. The updated results showed a 31% confirmed overall response rate in 26 evaluable patients with high B7-H4 expressing tumors at intermediate doses. Notably, among patients who had received four or fewer prior lines of therapy, the response rate increased to 44%.
The clinical data, presented at the ASCO 2025 Annual Meeting, highlight Emi-Le’s potential in treating aggressive cancers, including triple-negative breast cancer. Mersana is encouraged by the safety profile and early signs of tumor response in difficult-to-treat cancers. These promising findings support continued research and possible expansion of Emi-Le’s use in multiple cancer types with high unmet medical needs.
Read Announcement- Drug:
- XMT-1660
- Announced Date:
- March 3, 2025
- Indication:
- High unmet need tumors such as breast, endometrial and ovarian
Announcement
Mersana Therapeutics, Inc. provided a business update
AI Summary
Mersana Therapeutics, Inc. provided an update on its business progress and financial results, highlighting advances with its lead ADC candidate, Emi-Le. The company shared positive initial Phase 1 clinical data for Emi-Le, which is designed for patients with HER2-negative cancers, including triple-negative breast cancer (TNBC). In a key expansion cohort, TNBC patients who had previously received at least one topo-1 antibody-drug conjugate are now being treated with a dose of 67.4 mg/m² every four weeks. Additionally, the FDA awarded Emi-Le a Fast Track designation, underlining the compound’s potential to address a high unmet need. Mersana is also exploring higher doses in dose escalation and backfill cohorts, with more clinical data scheduled for presentation in 2025. This update reflects the company’s focused efforts to offer new treatment options for hard-to-treat cancers while advancing its promising pipeline.
Read Announcement- Drug:
- XMT-1660
- Announced Date:
- January 10, 2025
- Indication:
- High unmet need tumors such as breast, endometrial and ovarian
Announcement
Mersana Therapeutics, announced the U.S. Food and Drug Administration (FDA) recently granted an additional Fast Track designation to XMT-1660.
AI Summary
Mersana Therapeutics announced that the U.S. FDA has granted an additional Fast Track designation for its cancer treatment candidate, XMT-1660. This new designation targets advanced or metastatic breast cancer in patients with HER2 low or HER2-negative disease, including those with triple-negative breast cancer (TNBC), who have already received a topoisomerase-1 inhibitor ADC. The Fast Track status is intended to facilitate the development of XMT-1660, offering benefits such as more frequent meetings and communications with the FDA to speed up its review process. This move underlines the growing need for effective treatment options in patient groups that are notably challenging to treat. Mersana’s announcement reinforces its commitment to advancing promising therapies for serious conditions and highlights the potential benefits of the Fast Track program in expediting the development of new treatments.
Read Announcement- Drug:
- XMT-1660
- Announced Date:
- January 10, 2025
- Indication:
- High unmet need tumors such as breast, endometrial and ovarian
Announcement
Mersana Therapeutics, announced positive initial clinical data from the Phase 1 dose escalation and backfill cohorts for emiltatug ledadotin (Emi-Le; XMT-1660), Mersana's lead Dolasynthen ADC candidate targeting B7-H4.
AI Summary
Mersana Therapeutics announced promising early clinical data from the Phase 1 dose escalation and backfill cohorts for its lead Dolasynthen ADC candidate, emiltatug ledadotin (Emi-Le; XMT-1660). The trial showed that Emi-Le is generally well tolerated with a distinct safety profile compared to other ADCs. Importantly, the data revealed confirmed responses across various tumor types, including several patients with triple-negative breast cancer (TNBC) who had already been treated with a topoisomerase-1 inhibitor ADC. These encouraging findings led to the initiation of a first expansion cohort specifically for TNBC patients meeting this criterion. The company noted that Emi-Le demonstrated promising clinical activity even in heavily pretreated patients, marking a potential new treatment option for those with high unmet needs. Mersana expects to achieve further milestones in 2025 as it continues dose exploration and additional clinical data presentations.
Read Announcement
Mersana Therapeutics FDA Events - Frequently Asked Questions
As of now, Mersana Therapeutics (MRSN) has not received any FDA approvals for its therapy in the last two years.
In the past two years, Mersana Therapeutics (MRSN) has reported FDA regulatory activity for XMT-1660.
The most recent FDA-related event for Mersana Therapeutics occurred on June 2, 2025, involving XMT-1660. The update was categorized as "Additional data," with the company reporting: "Mersana Therapeutics, announced additional interim Phase 1 clinical data for emiltatug ledadotin (Emi-Le; XMT-1660), the company's B7-H4-directed Dolasynthen ADC."
Currently, Mersana Therapeutics has one therapy (XMT-1660) targeting the following condition: High unmet need tumors such as breast, endometrial and ovarian.
More FDA Event Resources from MarketBeat
FDA Event Stage Terminology & Abbreviation Guide
- NDA: New Drug Application
- ANDA: Abbreviated New Drug Application
- sNDA: Supplemental New Drug Application
- BLA: Biologics License Application
- sBLA: Supplemental Biologics License Application
- FDA Approved: Approved by the FDA
- EMA: European Medicines Agency
- CE Mark: European Union Certification
- NMPA: China National Medical Products Administration
- MHLW: Japanese Ministry of Health
- FDA Meeting: Consultation with FDA
- Pre-IND: Pre-Investigational New Drug Meeting
- Breakthrough Therapy: Special FDA designation for promising therapies
- Fast Track: Accelerated FDA approval pathway
- Orphan Drug: Designation for rare disease treatments
- RPD: Rare Pediatric Disease Designation
- RMAT: Regenerative Medicine Advanced Therapy
- DSMB Review: Data Safety Monitoring Board Review
- IDMC Review: Independent Data Monitoring Committee
- MAA: MHRA Marketing Authorization Application
- RTF: Refusal to File (Rejected Application)
- 510(k): FDA Clearance for Medical Devices
- Rolling Submission: Staggered regulatory review process
This page (NASDAQ:MRSN) was last updated on 7/10/2025 by MarketBeat.com Staff
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