On October 13, 2026 Prelude Therapeutics Incorporated (Nasdaq: PRLD), a precision oncology company, reported a clinical trial collaboration and supply agreement with Eli Lilly and Company ("Lilly") for supply of its CDK4/6 kinase inhibitor, abemaciclib and its oral estrogen receptor antagonist, imlunestrant. The agreement supports the evaluation of Prelude’s clinical development candidate PRT13722, an oral KAT6A selective degrader, in combinations with abemaciclib and imlunestrant in a Phase 1 trial in patients with HR+/HER2- breast cancer.
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The U.S. Food and Drug Administration (FDA) recently cleared the Company 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 beginning with monotherapy dose escalation and rapidly advancing to various combination cohorts.
"This collaboration with Lilly enables us to evaluate the potential of PRT13722 in combinations with abemaciclib and imlunestrant in patients with HR+ breast cancer," stated 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."
At the American Association for Cancer Research (AACR) (Free AACR Whitepaper) 2026 Annual Meeting in April of this year, Prelude presented preclinical data that demonstrated PRT13722, by selectively degrading KAT6A, drives more complete disruption of the KAT6A regulatory pathways than dual KAT6A/B inhibitors, resulting in more robust depth and breadth of efficacy across HR+/HER2- breast cancer models. Additionally, PRT13722 drove durable complete tumor regressions in HR+/HER2- CDX and PDX xenograft models (both endocrine therapy naive and experienced) at well tolerated doses, as a monotherapy. In combinations with endocrine therapy, CDK4/6 inhibitors and PI3K inhibitors, PRT13722 demonstrated synergy while maintaining monotherapy and combination activity across HR+ breast cancer models, including ESR1 mutated and acquired therapy-resistant cancer cells. PRT13722 also demonstrated preclinically an improved hematological safety profile compared to the KAT6A/B dual inhibitor prifetrastat, which may enable combinations with standard of care agents used in the frontline treatment of metastatic and early-stage HR+/HER2- breast cancer.
Prelude maintains full global development and commercial rights to PRT13722 as a wholly owned program.
Highly selective KAT6A oral degrader program
KAT6 is an emerging and clinically validated target in the treatment of HR+ breast cancer. Prelude discovered and is developing first-in-class, highly potent, highly selective and orally bioavailable KAT6A degraders. Prelude believes that selectively degrading KAT6A and sparing KAT6B has the potential for improved efficacy, tolerability and combinability with other agents relative to dual inhibitors of KAT6A/B.
(Press release, Prelude Therapeutics, OCT 13, 2026, View Source [SID1234673373])