Circle Pharma has raised an oversubscribed $92.5 million Series E financing to advance CID-165, its first-in-class oral macrocyclic cyclin D1 RxL inhibitor, into clinical development for ER-positive breast cancer. The round was led by The Column Group, with participation from Nextech Invest, RA Capital Management, Euclidean Capital and Eli Lilly and Company.
Circle Pharma expects CID-165 to enter clinical development during the first quarter of 2027. The funding will support its early clinical program as well as continued development of the company’s broader pipeline of cyclin-targeted macrocycles.
Cyclin D1 plays an important role in cell-cycle progression and can become dysregulated in cancers including ER-positive breast cancer and certain lymphomas. In those cancers, cyclin D1 can promote abnormal proliferation by inactivating the tumor-suppressor retinoblastoma protein.
CID-165 is designed to selectively disrupt the interaction between cyclin D1 and retinoblastoma protein, allowing the tumor suppressor to remain active.
Circle Pharma said the candidate has demonstrated anti-tumor activity in cyclin D1-driven preclinical models both as a monotherapy and when used with CDK4/6-dual inhibitors, CDK4-selective inhibitors and endocrine therapies.
The company is developing macrocyclic therapeutics to address biological targets that have historically been difficult to drug with conventional small molecules.
KEY QUOTES:
“Momentum around our cyclin D1 program has continued to build as CID-165 advances toward the clinic. We believe CID-165 has the potential to become a new backbone therapy for ER-positive breast cancer and this financing provides us with the resources to generate meaningful clinical data to validate that potential.”
David J. Earp, J.D., Ph.D., President and Chief Executive Officer of Circle Pharma
“CID-165 is designed to selectively disrupt the interaction between cyclin D1 and retinoblastoma protein, providing a novel approach to directly targeting this fundamental driver of tumor growth.”
Marie Evangelista, Ph.D., Chief Scientific Officer of Circle Pharma
