New Breast Cancer Drug Trial Collaboration Announced
The Phase 1 study will test a new oral degrader in combination with existing endocrine therapies for patients.
Updated on Oct. 13, 2026 in Cancer
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Prelude Therapeutics has entered a collaboration with Eli Lilly to test an experimental breast cancer treatment called PRT13722. The Phase 1 clinical trial, which combines the drug with established therapies, will begin enrolling participants in late 2026.
Why it matters
This partnership explores a potential new treatment pathway by pairing an experimental drug with standard care for breast cancer. The research seeks to build on preclinical findings suggesting that combining these therapies may offer more effective results than using them alone.
The upcoming Phase 1 study will evaluate the safety and preliminary efficacy of PRT13722, an oral KAT6A selective degrader. This follows preclinical data presented at the 2026 AACR Annual Meeting demonstrating synergistic activity between the investigational drug and existing endocrine treatments.
The players
Prelude Therapeutics
A Wilmington-based biotechnology company focused on the development of precision cancer medicines.
Eli Lilly
A global pharmaceutical company known for developing treatments for oncology, diabetes, and endocrine conditions.
The details
The study will begin with monotherapy dose escalation before testing PRT13722 in combination with abemaciclib, a CDK4/6 inhibitor, and imlunestrant, an oral estrogen receptor antagonist. These combinations aim to leverage the biological synergy identified in earlier laboratory models. Prelude Therapeutics retains full global development and commercial rights to the experimental drug as it enters human trials.
Timeline
Preclinical data was presented at the AACR Annual Meeting in April 2026.
The collaboration agreement was officially announced on October 13, 2026.
Patient enrollment for the Phase 1 trial is expected to begin in Q4 2026.
Health Landscape
This study reflects the ongoing shift in oncology toward combining novel targeted degraders with established endocrine therapies to overcome treatment resistance. It follows a research trajectory established by findings at the AACR 2026 Annual Meeting, aiming to refine combination protocols for breast cancer.
Early-phase trials like this are highly specialized and primarily intended to establish safety and dosing ranges in a clinical setting. If you are managing breast cancer and have questions about whether a clinical trial is a suitable step for your care plan, speak with your oncologist.
The takeaway
This trial represents the jump from preclinical discovery to human testing for a new class of cancer medication. Discussing clinical trial options with your care team remains an important way to stay informed about emerging treatment pathways.
Further reading
Learn more about the latest research and standard treatment approaches at our Cancer hub.
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