# Circle Pharma

Source: https://onco.cc/companies/circle-pharma/  
OnCo record `circle-pharma` (Company). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Circle Pharma is developing CID-078, the first oral cyclin A/B RxL inhibitor, aimed at cancers with a broken G1/S checkpoint such as small-cell lung and triple-negative breast cancer.

## Summary

CID-078 is an orally bioavailable macrocyclic peptide that blocks RxL-motif interactions of cyclins A and B, selectively killing E2F-high, RB1-altered tumour cells. Phase 1 (NCT06577987) began in October 2024 in advanced solid tumours including SCLC, TNBC, and ER+ breast cancer after CDK4/6 inhibitors; preclinical work published in Nature; clinical and preclinical updates at AACR 2026.

## Fields

- Kind: Company
- Last checked: 2026-09-04
- HQ: South San Francisco, CA
- Type: biotech
- Website: https://circlepharma.com

## Sources

- AACR 2026 presentations: https://circlepharma.com/circle-pharma-to-present-new-clinical-and-preclinical-data-at-aacr-2026

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Small-cell lung cancer](https://onco.cc/cancers/sclc/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- fronts: [Targeted Therapy](https://onco.cc/fronts/targeted-therapy/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/)
- pathways: [p53 / RB / cell-cycle checkpoint](https://onco.cc/pathways/p53-cell-cycle/)
- ideas: [Macrocyclic peptides to cover protein surfaces that pills cannot](https://onco.cc/ideas/idea-bio1-macrocycle-ppi-campaign/)

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JSON: https://onco.cc/api/v1/entities/circle-pharma.json