• RGT-419B, a next generation CDK4 inhibitor, was safe and well tolerated in a First-in-Human Phase 1A single agent dose escalation study.
  • Monotherapy clinical efficacy was observed in HR+/HER2- advanced breast cancer (ABC) patients who have progressed on CDK4/6 inhibitors (CDK4/6is) and endocrine therapy (ET).
  • The current data support the continued development of RGT-419B as a single agent, as well as in combination therapy with ET in HR+/HER2- ABC patients.

BOSTON, Dec. 8, 2023 /PRNewswire/ — Regor Therapeutics Group (“Regor”), a global innovator powered by cutting-edge drug discovery engine and differentiated clinical development pipeline, today announced the results from Phase 1A single agent dose escalation study of RGT-419B, a next generation CDK4 inhibitor, in HR+ HER2- ABC patients who have progressed on prior CDK4/6is and ET. These results (cutoff date September 26, 2023) were presented today in poster session by Dr. Seth Wander from Massachusetts General Hospital at the San Antonio Breast Cancer Symposium (SABCS) taking place December 5-9, 2023, in San Antonio, Texas. The poster titled “First-in-human Phase 1A study of RGT-419B, a next generation CDK4 inhibitor, in patients with HR+/HER2- ABC who have progressed on prior CDK4/6 inhibitors (PO3-18-06; NCT05304962)”, highlighted that:

  • Across 12 patients with HR+HER2- ABC who have progressed on CDK4/6is and ET, RGT-419B administered as oral (PO) monotherapy in continuous 28-day cycles was safe and well-tolerated with no dose-limiting toxicities. No patients discontinued treatment with RGT-419B due to an adverse event.
  • The exposure of RGT-419B was dose proportional with long half-life and small peak to trough ratio at steady state.
  • RGT-419B demonstrated single agent efficacy in the heavily pretreated HR+/HER2- ABC patients who have progressed on CDK4/6i and ET. Three patients achieved partial responses and are still on treatment. 6 patients received treatment > 24 weeks.
  • The promising single agent efficacy of RGT-419B is consistent with the preclinical data from CDK4/6i resistant breast cancer models.

“RGT-419B demonstrates its potential to be the best-in-class next generation CDK4 inhibitor for HR+/HER2- breast cancer. The results presented today is encouraging because RGT-419B is not only safe and well tolerated, but also demonstrated single agent efficacy in heavily pre-treated HR+ HER2- ABC patients who progressed on the approved CDK4/6i and ET.” said Xiayang Qiu Ph.D., Chief Executive Officer of Regor Therapeutics Group. “These data show that RGT-419B has monotherapy opportunity in HR+ HER2- ABC patients resistant to the approved CDK4/6i and ET.  With the favorable safety profile and promising monotherapy efficacy, RGT-419B has best-in-class potential as a single agent or in combination in HR+HER2- BC patients resistant to CDK4/6i, and in earlier lines of treatments.  Clinical studies of single agent dose expansion and combination of RGT-419B with ET are underway.”

The Phase 1 trial (NCT05304962) is a multicenter, open-label study to assess the safety, tolerability, pharmacokinetics and preliminary anti-tumor activity of RGT-419B given as monotherapy or in combination with ET in patients with HR+HER2- ABC who have progressed on CDK4/6i and ET.

Copies of the posters are available on Regor’s website under the Science section.

About Regor Therapeutics Group                                   

Regor Therapeutics Group is a biotech founded in 2018 by a team of scientists with a proven track record in drug discovery and executive leadership covering full cycle of drug discovery and development. By leveraging its industry-leading core strength in rCARD™ (Computer Accelerated Rational Discovery), Regor has completed 8 PCCs inhouse, with 5 INDs filed, validating Regor’s highly efficient ecosystem for accelerated discovery of innovative therapeutic agents.

Regor’s in-house pipeline encompasses leading assets in metabolism, oncology and auto-immunity, with 2 leading assets: 1) RGT-075, an orally bioavailable small molecule GLP1R full agonist with best-in-class potential for obesity & beyond; and 2) RGT-419B, a unique CDK4+ inhibitor showing outstanding single agent responses in refractory ER+/Her2- breast cancer patients.

With a strong focus on excellence in pharmaceutical research and global competitiveness, Regor aspires to build a world-class innovation engine that promotes a winning culture of scientific excellence, strong teamwork driven by results and delivery with shared accountability and successes.

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