Breast Cancer Coverage from Every Angle

Novel CDK4/6 Inhibitor Plus Fulvestrant Under Study in Advanced Breast Cancer

By: Kelly M. Hennessey, PhD
Posted: Wednesday, November 18, 2020

The combination of fulvestrant with CDK4/6 inhibitors has improved progression-free survival in patients with hormone receptor–positive/HER2-negative advanced breast cancer. However, side effects include neutropenia and gastrointestinal disorders, present dosing, and toxicity issues. Iurie Bulat, MD, of the Institute of Oncology, Chisinau, Moldova, and colleagues assessed the safety of novel CDK4/6 inhibitor, lerociclib (G1T38), in combination with fulvestrant. They found low rates of gastrointestinal side effects and grade 3 or 4 neutropenia, along with comparable efficacy with other CDK4/6 combination therapies. The results of the phase II study were presented at the European Society for Medical Oncology (ESMO) Virtual Congress 2020 (Abstract 334P).

A total of 100 patients with hormone receptor–positive/HER2-negative advanced breast cancer that had progressed following endocrine therapy were enrolled. To determine the recommended dose of lerociclib, a dose range of 200 to 650 mg once daily and 100 to 250 mg twice daily was established, along with 500 mg of fulvestrant. Of the 20 patients who received 150 mg twice daily, 19 were evaluable for tumor response; 6 patients experienced a partial response, 9 patients had stable disease, and 4 patients experienced progressive disease. A clinical benefit rate of at least 24 weeks was achieved by 14 of 19 patients (74%.) Those who had no prior chemotherapy (n = 9) reached the highest clinical benefit rate of 89%.

As for toxicity, neutropenia (55%), leukopenia (40%), diarrhea (20%), and anemia (20%) were associated with the 150-mg twice daily dose of lerociclib. Of those patients experiencing adverse events, rates of grade 3 and 4 neutropenia were 30% and 5%, respectively. No grade ≥ 3 nausea, vomiting, or diarrhea adverse effects were reported.   

Disclosure: For full disclosures of the study authors, visit

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