emiltatug ledadotin (XMT-1660) / Servier - LARVOL DELTA

A phase 2 study of emiltatug ledadotin (Emi-Le) in patients with aggressive adenoid cystic carcinoma: EMBLEM-1 (ESMO 2026) - No abstract available

Clinical • P2 data • Adenoid Cystic Carcinoma • Oncology

Initial phase 1 dose escalation data for emiltatug ledadotin (Emi-Le), a novel B7-H4-directed dolasynthen antibody-drug conjugate. (ASCO 2025) - P1 | "Emi-Le (XMT-1660) is a B7-H4-directed Dolasynthen ADC designed with a proprietary auristatin F-HPA microtubule inhibitor payload with controlled bystander effect... Based on the initial reported data, Emi-Le appears to have encouraging clinical activity and tolerability in a heavily pretreated population. Further clinical development is ongoing in the EXP portion of the trial at a dose of 67.4 mg/m2 Q4W in pts with advanced/metastatic TNBC who have received 1-4 prior lines of systemic therapy, including at least one topo-1 ADC. Dose exploration is ongoing to identify a potential second higher EXP dose."

P1 data • Adenoid Cystic Carcinoma • Fatigue • Interstitial Lung Disease • Neutropenia • Oncology • Optic Neuritis • Pain • Pulmonary Disease • Renal Disease • Respiratory Diseases • Thrombocytopenia • Triple Negative Breast Cancer • HER-2 • VTCN1

Emiltatug ledadotin (Emi-Le): A B7-H4-directed dolasynthen antibody-drug conjugate (ADC) being investigated in phase 1 dose expansion in patients with triple negative breast cancer who received at least one prior topoisomarase-1 inhibitor ADC. (ASCO 2025) - P1 | "Emiltatug ledadotin (Emi-Le; XMT-1660) is a B7-H4-directed Dolasynthen ADC designed with a precise, target-optimized drug-to-antibody ratio (DAR 6) and a proprietary auristatin F-HPA microtubule inhibitor payload with controlled bystander effect...The protocol includes the option for multiple additional indications, including HR+/HER2- breast cancer, endometrial cancer, ovarian cancer, and ACC-1. NCT05377996"

Clinical • P1 data • Breast Cancer • Endometrial Cancer • HER2 Breast Cancer • HER2 Negative Breast Cancer • HER2 Positive Breast Cancer • Oncology • Ovarian Cancer • Solid Tumor • Triple Negative Breast Cancer • HER-2 • VTCN1

Emiltatug ledadotin (Emi-Le), a B7-H4–directed antibody-drug conjugate (ADC), in patients with aggressive adenoid cystic carcinoma (ACC): Phase 1 interim analysis. (ASCO 2026) - P1 | "Based on these data, Emi-Le appears to demonstrate favorable tolerability and promising antitumor activity in pts with aggressive ACC who have no available treatments and a poor prognosis. Further clinical development is ongoing."

ADC • Clinical • P1 data • Adenoid Cystic Carcinoma • Oncology • Renal Disease • MYC • NOTCH1 • TP63 • VTCN1

Clinical activity of emiltatug ledadotin (Emi-Le), a B7-H4-directed ADC, in patients with TNBC who received at least one prior topoisomerase-1 inhibitor (Topo-1) ADC (ESMO-BC 2025) - P1 | "Based on the initial reported data, Emi-Le appears to have encouraging clinical activity and tolerability in a heavily pretreated TNBC population with high B7-H4 expression who had previously received topo-1 ADCs. Further clinical development of Emi-Le is ongoing in the expansion portion of the Ph1 trial at a dose of 67.4 mg/m2 Q4W in pts with advanced/metastatic TNBC who have received 1-4 prior lines of systemic therapy, including at least one topo-1 ADC."

Clinical • Triple Negative Breast Cancer • VTCN1

MER-XMT-1660-1: A Study of Emiltatug Ledadotin (Emi-Le) in Participants With Solid Tumors (clinicaltrials.gov) - P1/2 | N=360 | Recruiting | Sponsor: Day One Biopharmaceuticals, Inc. | Phase classification: P1 ➔ P1/2 | Trial completion date: May 2027 ➔ Dec 2027

First-in-human • Phase classification • Trial completion date • Adenoid Cystic Carcinoma • Breast Cancer • Endometrial Cancer • Estrogen Receptor Positive Breast Cancer • Fallopian Tube Cancer • Hormone Receptor Positive Breast Cancer • Oncology • Ovarian Cancer • Solid Tumor • Triple Negative Breast Cancer

A Study of XMT-1660 in Participants With Solid Tumors (clinicaltrials.gov) - P1 | N=166 | Recruiting | Sponsor: Mersana Therapeutics | Phase classification: P1b ➔ P1

Phase classification • Breast Cancer • Endometrial Cancer • Fallopian Tube Cancer • Oncology • Ovarian Cancer • Solid Tumor • Triple Negative Breast Cancer

A Study of XMT-1660 in Participants With Solid Tumors (clinicaltrials.gov) - P1 | N=166 | Recruiting | Sponsor: Mersana Therapeutics

Trial completion date • Trial primary completion date • Breast Cancer • Endometrial Cancer • Fallopian Tube Cancer • Oncology • Ovarian Cancer • Solid Tumor • Triple Negative Breast Cancer

A Study of XMT-1660 in Participants With Solid Tumors (clinicaltrials.gov) - P1 | N=319 | Recruiting | Sponsor: Mersana Therapeutics | N=166 ➔ 319 | Trial completion date: Jan 2026 ➔ May 2027 | Trial primary completion date: Jan 2025 ➔ Dec 2026

Enrollment change • Trial completion date • Trial primary completion date • Adenoid Cystic Carcinoma • Breast Cancer • Endometrial Cancer • Fallopian Tube Cancer • Oncology • Ovarian Cancer • Solid Tumor • Triple Negative Breast Cancer

Promising Phase 1 Data for Servier's Emiltatug Ledadotin (Emi-Le) in Adenoid Cystic Carcinoma (ACC) Presented at ASCO 2026 (PRNewswire) - "Emi-Le was well-tolerated demonstrating a distinct and potentially differentiated emerging safety profile....Promising signals of efficacy among 45 evaluable participants with ACC. Objective response rate (ORR) was 35.6%, including one complete response. Disease control rate was 82.2%....Consistent tumor shrinkage, with an ORR of 46.9%, DCR of 81.3% and median PFS of 7.8 months."

P1 data • Adenoid Cystic Carcinoma

Results from an ongoing Phase 1 trial evaluating investigational compound Emi-Le in adenoid cystic carcinoma will be shared in an oral presentation (PRNewswire) - "The data reveal that Emi-Le demonstrates favorable tolerability and promising antitumor activity in patients with aggressive ACC who have no available treatment options and a poor prognosis. Further clinical development is ongoing."

P1 data • Adenoid Cystic Carcinoma

Emiltatug Ledadotin (Emi-Le) Granted Breakthrough Therapy Designation by the U.S. FDA for Adenoid Cystic Carcinoma (ACC) (PRNewswire) - "In the initial data reported from Phase 1, Emi-Le had manageable side effects, and confirmed objective responses were observed across multiple tumor types."

Breakthrough therapy • Adenoid Cystic Carcinoma

Servier completes the acquisition of Day One Biopharmaceuticals (Canada Newswire) - "Acquisition expands Servier's position in oncology with tovorafenib marketed as OJEMDA in the U.S. in pediatric low-grade glioma; Transaction also includes a strong oncology pipeline of clinical stage assets in rare cancers with high unmet needs; Transaction represents total equity value of approximately $2.5 billion....The transaction also strengthens Servier's oncology pipeline from early clinical to Phase 3. In addition to tovorafenib, which is being investigated in additional indications, Day One's pipeline includes Emi-Le (emiltatug ledadotin), a novel antibody drug conjugate (ADC) and DAY301, a targeted therapy in rare cancers."

M&A • Adenoid Cystic Carcinoma • Glioma • Low Grade Glioma • Solid Tumor

Servier and Day One Biopharmaceuticals announce acquisition to expand Servier's rare oncology portfolio (PRNewswire.co.uk) - "Servier...and Day One Biopharmaceuticals, Inc...announced that they have entered into a definitive agreement for Servier to acquire Day One for $21.50 per share in cash, representing a total equity value of approximately $2.5 billion. The transaction remains subject to customary closing conditions and is expected to close in the second quarter of 2026...It strengthens Servier's portfolio and expands its oncology pipeline with programs ranging from early stage to phase 3."

M&A • Adenoid Cystic Carcinoma • Glioma

2026 Corporate Priorities and Key Milestones:…PIPELINE (GlobeNewswire) - "(i) Advance Emi-Le program by delivering Phase 1 clinical data by mid-2026 and progressing toward registration; (ii) Provide initial data from the Phase 1a clinical trial for DAY301, a PTK7-targeted antibody drug conjugate (ADC), in the second half of 2026."

P1 data • Solid Tumor

Day One Completes Acquisition of Mersana Therapeutics (GlobeNewswire) - "Acquisition expands Day One’s pipeline with clinical-stage antibody drug conjugate (ADC) emiltatug ledadotin (Emi-Le) targeting rare cancer adenoid cystic carcinoma (ACC)...Day One has acquired all outstanding shares of Mersana common stock at a price of $25 per share in cash, plus one non-tradable CVR per share to receive certain potential milestone payments of up to an aggregate of $30.25 per CVR in cash, for total consideration of up to $55.25 per share in cash."

M&A • Adenoid Cystic Carcinoma

Emiltatug Ledadotin (Emi-Le; XMT-1660) (GlobeNewswire) - "As of October 1, 2025, Mersana has enrolled a substantially greater number of ACC-1 patients in these backfill cohorts than was presented at ASCO. The data from ACC-1 patients enrolled in this trial continues to mature as Mersana enrolls additional patients and patients remain on treatment for longer periods. Mersana has continued to be encouraged by the responses of the patients in these backfill cohorts....Emi-Le continues to be generally well-tolerated, and its observed safety profile remains consistent with previously disclosed data."

Enrollment status • P1 data • Adenoid Cystic Carcinoma

Day One to Acquire Mersana Therapeutics to Advance Mission to Bring New Medicines to People of All Ages with Life-Threatening Diseases (GlobeNewswire) - "The transaction positions the Company for continued success and expansion of its oncology portfolio, adding Emi-Le, a potential first-in-class monotherapy for patients with ACC, an aggressive cancer with a well-defined patient population and high unmet need, most often arising from the salivary gland."

M&A • Adenoid Cystic Carcinoma

Emiltatug Ledadotin (Emi-Le): A B7-H4-Directed Dolasynthen Antibody-Drug Conjugate (ADC) Being Investigated in Phase 1 Dose Expansion in Patients with Triple Negative Breast Cancer who Received at Least One Prior Topoisomarase-1 Inhibitor ADC [WITHDRAWN] (SABCS 2025) - No abstract available

Clinical • P1 data • Breast Cancer • Oncology • Solid Tumor • Triple Negative Breast Cancer • VTCN1

Mersana Therapeutics Provides Business Update... (GlobeNewswire) - "More than 45 patients enrolled in Emi-Le Phase 1 dose expansion cohorts in post topoisomerase-1 inhibitor ADC (post-topo-1) triple-negative breast cancer (TNBC); Plan to report initial clinical data from Emi-Le expansion cohorts in second half of 2025."

P1 data • Trial status • Triple Negative Breast Cancer

Mersana Therapeutics Reports Additional Positive Interim Phase 1 Clinical Data for Emi-Le in Oral Presentation at 2025 ASCO Annual Meeting (GlobeNewswire) - P1 | N=319 | NCT05377996 | Sponsor: Mersana Therapeutics | "Safety and tolerability as of the March 8, 2025 data cut-off were consistent with initial data previously reported in January 2025, and no new safety signals were observed....31% confirmed objective response rate (ORR) (8/26) across all enrolled tumor types with B7-H4 high tumor expression (defined as a tumor proportion score of 70% or higher) receiving intermediate Emi-Le doses (38.1 milligrams per meter squared (mg/m2) to 67.4 mg/m2 per cycle)....56% ORR (5/9, including one unconfirmed response as of the March 8, 2025 data cut-off that was subsequently confirmed) in ACC-1 regardless of dose and B7-H4 expression. Among all ACC-1 patients who were enrolled in the Phase 1 clinical trial, the median progression free survival (PFS) had not yet been reached as of the March 8, 2025 data cut-off."

P1 data • Adenoid Cystic Carcinoma • Endometrial Cancer • Hormone Receptor Positive Breast Cancer • Ovarian Cancer • Triple Negative Breast Cancer

CORRECTION - Mersana Therapeutics Provides Business Update and Announces First Quarter 2025 Financial Results (GlobeNewswire) - "Mersana continues to advance the dose expansion portion of its Phase 1 clinical trial of Emi-Le in patients with TNBC who have received one to four prior lines of therapy, including at least one topo-1 ADC. In recent months, the company has made significant progress in the enrollment of patients in its 'Dose A' cohort, in which patients are receiving 67.4 mg/m² of Emi-Le every four weeks (Q4W)...Mersana also recently initiated enrollment in its 'Dose B' cohort. These patients are receiving a starting dose of 44.5 mg/m2 of Emi-Le on days 1 and 8 of the first four-week cycle followed by 80 mg/m2 of Emi-Le Q4W...The company plans to report initial clinical data from the expansion portion of its Phase 1 clinical trial in the second half of 2025...Mersana plans to continue enrolling patients in dose escalation and expects to present initial clinical pharmacodynamic STING activation data for XMT-2056 in 2025."

P1 data • Trial status • Solid Tumor • Triple Negative Breast Cancer • HER-2

Updated Clinical Data Presented at ESMO Breast Cancer 2025 Today (GlobeNewswire) - P1 | N=319 | NCT05377996 | Sponsor: Mersana Therapeutics | "Earlier this morning at the European Society for Medical Oncology Breast Cancer 2025 Annual Congress...updated clinical data as of a March 8, 2025 data cutoff from Emi-Le’s Phase 1 dose escalation and backfill cohorts were presented...The presentation included clinical activity data among evaluable patients (those with measurable disease at baseline and at least one post-baseline scan) across all tumor types (TNBC, hormone-receptor-positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer; ovarian cancer; endometrial cancer and adenoid cystic carcinoma type 1) with B7-H4 high tumor expression (defined as a tumor proportion score of 70% or higher) who received intermediate Emi-Le doses of 38.1 milligrams per meter squared (mg/m2) to 67.4 mg/m2 per cycle. For these patients, the confirmed objective response rate (ORR) was 31% (8 of 26 patients)."

P1 data • Endometrial Cancer • HER2 Negative Breast Cancer • Hormone Receptor Positive Breast Cancer • Ovarian Cancer • Triple Negative Breast Cancer

Mersana Therapeutics Announces Strategic Restructuring and Reprioritization Plan Focused on Advancing Emi-Le in Triple-Negative Breast Cancer (GlobeNewswire) - "Mersana Therapeutics, Inc...announced the implementation of a strategic restructuring and reprioritization plan aimed at extending the company’s cash runway and furthering the development of emiltatug ledadotin (Emi-Le; XMT-1660), the company’s B7-H4-directed Dolasynthen ADC...Mersana’s strategic restructuring and reprioritization plan will reduce the company’s workforce by approximately 55% across functions. The workforce reduction is expected to be substantially complete by the end of the third quarter of 2025...The company will also reduce its research activities and eliminate its internal pipeline development efforts. In the near term, Mersana will focus Emi-Le development efforts on breast cancer to enable the generation of additional safety, tolerability and clinical activity data. Mersana plans to continue supporting its Phase 1 dose escalation work for XMT-2056 and its ongoing collaborations....Collectively, these actions..."

Pipeline update • Solid Tumor

Mersana Therapeutics Announces Upcoming Emi-Le Oral and Poster Presentations at ASCO 2025 Annual Meeting (GlobeNewswire) - "Mersana Therapeutics, Inc...today announced that the following presentations related to emiltatug ledadotin (Emi-Le; XMT-1660), Mersana’s B7-H4-directed Dolasynthen ADC, will be given at the American Society of Clinical Oncology (ASCO) 2025 Annual Meeting taking place May 30-June 3, 2025 at McCormick Place, Chicago, IL."

Clinical data • Triple Negative Breast Cancer