Prelude Therapeutics , a Wilmington, Delaware-based precision oncology company, announced on October 13, 2026 a clinical trial collaboration and supply agreement with Eli Lilly and Company. Lilly will supply its CDK4/6 inhibitor abemaciclib (Verzenio®) and its oral estrogen receptor antagonist imlunestrant (Inluriyo®) so Prelude can evaluate them in combination with PRT13722, its oral KAT6A selective degrader, in a Phase 1 trial in patients with HR+/HER2- breast cancer.
“This collaboration with Lilly enables us to evaluate the potential of PRT13722 in combinations with abemaciclib and imlunestrant in patients with HR+ breast cancer,” said Sean Brusky, Chief Business & Strategy Officer of Prelude. “We are taking a highly differentiated approach to this clinically validated target. Our preclinical data demonstrate that selectively degrading KAT6A has the potential to improve upon the efficacy and hematologic toxicity seen with dual KAT6A/B inhibitors, thereby enabling combination approaches that could advance the standard of care in earlier lines of therapy. We are pleased to be partnering with Lilly, recognized global leaders in breast cancer, to generate these important data for patients.”
Phase 1 Trial Set to Begin Enrolling
The FDA recently cleared Prelude to proceed with the Phase 1 study under its Investigational New Drug (IND) application for PRT13722. The company expects to begin enrolling patients in the fourth quarter of 2026, starting with monotherapy dose escalation and then moving quickly into combination cohorts. Prelude retains full global development and commercial rights to PRT13722 as a wholly owned program.
A Selective Approach to a Validated Target
KAT6 is an emerging, clinically validated target in HR+ breast cancer. Prelude’s approach selectively degrades KAT6A while sparing KAT6B, which the company believes could improve efficacy, tolerability, and the ability to combine with other agents compared with dual KAT6A/B inhibitors.
At the American Association for Cancer Research (AACR) 2026 Annual Meeting in April, Prelude presented preclinical data showing that PRT13722 more completely disrupted KAT6A regulatory pathways than dual KAT6A/B inhibitors, with deeper and broader efficacy across HR+/HER2- breast cancer models. As a monotherapy, it drove durable complete tumor regressions in xenograft models at well-tolerated doses, in models both naive to and previously treated with endocrine therapy.
In combination with endocrine therapy, CDK4/6 inhibitors, and PI3K inhibitors, PRT13722 showed synergy across HR+ breast cancer models, including ESR1-mutated and therapy-resistant cancer cells. Preclinically, it also showed an improved hematological safety profile compared with the dual KAT6A/B inhibitor prifetrastat, which could enable combinations with standard-of-care agents used in frontline treatment of metastatic and early-stage HR+/HER2- breast cancer.
About Prelude Therapeutics
Prelude Therapeutics is a precision oncology company developing medicines in areas of high unmet need for cancer patients. Its pipeline includes highly selective KAT6A degraders and JAK2V617F mutant-selective inhibitors, and it is applying its targeted protein degradation expertise to develop next-generation degrader antibody conjugates (DACs) with novel payloads
