Clinical Summary:

• Design/Population: Analysis of emiltatug ledadotin (Emi-Le; XMT-1660), a B7-H4-directed antibody-drug conjugate, in patients with aggressive adenoid cystic carcinoma, a rare malignancy associated with limited treatment options and poor outcomes.

• Key Outcomes: Among 25 evaluable patients with ACC, Emi-Le achieved an objective response rate of 40% and a disease control rate of 76%. Median progression-free survival and overall survival had not yet been reached at the time of analysis. Across 221 treated patients, the safety profile was generally favorable, with low treatment discontinuation rates and no treatment-related deaths reported.
• Clinical Relevance: These findings suggest that Emi-Le may represent a promising new therapeutic option and support continued clinical development of this B7-H4-targeted antibody-drug conjugate.

Glenn Hanna, MD, Dana-Farber Cancer Institute, Boston, Massachusetts, presents data evaluating emiltatug ledadotin (Emi-Le; XMT-1660), a B7-H4-directed antibody-drug conjugate, in patients with aggressive adenoid cystic carcinoma (ACC), a rare cancer with limited treatment options and poor outcomes. 

Among 25 evaluable patients with ACC, Emi-Le achieved a 40% objective response rate and a 76% disease control rate, with median progression-free and overall survival not yet reached at the time of analysis, while demonstrating a generally favorable safety profile across 221 treated patients, with low discontinuation rates and no treatment-related deaths. 

These findings highlight the potential of Emi-Le as a promising new therapy for patients with aggressive ACC and support its continued clinical development. Dr Hanna presented these findings at the 2026 ASCO Annual Meeting in Chicago, Illinois.

Transcript: 

Hi, my name is Glenn Hanna, I'm a head and neck cancer specialist at Dana-Farber Cancer Institute in Boston, Massachusetts. I'm also an associate professor of medicine at Harvard Medical School, and I run the early drug development program at Dana-Farber.

I'm very excited to talk about Emi-Le, or emiltatug ledadotin (XMT-1660). These are the data we'll be presenting at ASCO this weekend. Emi-Le is a novel and differentiated B7-H4-directed antibody-drug conjugate. The trial population we'll be presenting results on is a group of patients with very high unmet needs and aggressive adenoid cystic carcinoma (ACC).

ACC is a rare salivary gland malignancy, and when it recurs or metastasizes, we don't have any FDA-approved treatment options. As a result, patients often face poor outcomes and limited therapeutic choices. So the data we're going to discuss are very exciting for this patient population.

The development of Emi-Le began in a traditional phase 1 study focused on safety, dose optimization, and early signals of activity across a number of different cancer types, including triple-negative breast cancer and, as we'll focus on here, aggressive adenoid cystic carcinoma.

The patients included in this analysis represented an aggressive ACC population. These are patients with high-risk disease features, including aggressive histopathologic characteristics, rapid progression after initial treatment, and, in some cases, molecular alterations associated with poorer outcomes. Many patients also had metastatic disease involving sites beyond the lungs, including bone, liver, and even the central nervous system.

I'm excited to say that Emi-Le demonstrated a generally favorable safety profile. Across 221 treated patients, we observed low treatment discontinuation rates and no treatment-related deaths. Overall, the drug was well tolerated, which is encouraging as we continue to evaluate its role in this disease.

The main finding was the level of antitumor activity observed in this patient population. Among 25 evaluable patients with aggressive ACC, Emi-Le achieved a 40% objective response rate and a 76% disease control rate. Importantly, the responses appear encouraging and durable. At the time of this analysis, median progression-free survival and median overall survival had not yet been reached, which speaks to the potential for meaningful and sustained clinical benefit in some patients.

We're extremely excited about Emi-Le and what these results may mean for patients with aggressive ACC. This is a disease with limited treatment options and significant unmet need, and these findings support the continued clinical development of this B7-H4-directed antibody-drug conjugate as a potential new therapeutic option.

I'll be sharing the full results of this study at the ASCO Annual Meeting, and we're thrilled by the potential impact this therapy could have for patients with aggressive adenoid cystic carcinoma.

Source:

Hanna GJ, Rabinowits G, Attarian S, et al. Emiltatug ledadotin (Emi-Le), a B7-H4–directed antibody-drug conjugate (ADC), in patients with aggressive adenoid cystic carcinoma (ACC): Phase 1 interim analysis. Presented at the ASCO Annual Meeting. May 29 - June 2, 2026. Chicago, Illinois. Abstract 6010.