Radiosurgery + Abemaciclib

Abemaciclib is an orally administered selective small-molecule inhibitor of CDK4 and CDK6 that is 14 times more potent against CDK4 than CDK6 in enzymatic assays that is approved for the treatment of advanced or metastatic breast cancers. Abemaciclib will be administered at a dose of 150 mg twice daily.

Abemaciclib will be administered with standard of care endocrine therapy. Endocrine therapy can consist of fulvestrant or an aromatase inhibitor. Dosing of concurrent endocrine therapy with abemaciclib should follow standard dosing and safety guidelines.

The study is designed as a prospective, single-arm, nonrandomized, open-label, phase I/II trial of abemaciclib and endocrine therapy with stereotactic radiosurgery (SRS) among patients with hormone receptor (HR)+/HER2- metastatic breast cancer brain metastases. Treatment will be initiated with one week of abemaciclib followed by stereotactic radiation to sites of brain metastases or post-operative cavities with continued abemaciclib.

This is a single arm study of abemaciclib and endocrine therapy with stereotactic radiosurgery (SRS) among patients with hormone receptor (HR)+/HER2- metastatic breast cancer brain metastases.

Live record on ClinicalTrials.gov →

• HR+ breast cancer to fulfill the requirement of HR+ disease, a breast cancer must express (≥ 1%), by immunohistochemistry (IHC), at least 1 of the hormone receptors (estrogen receptor [ER] or progesterone receptor [PR]) as defined in the American Society of Clinical Oncology (ASCO) / College of American Pathologists (CAP) Guidelines
• To fulfill the requirement of HER2- disease, a breast cancer must not demonstrate, at initial diagnosis or upon subsequent biopsy, overexpression of HER2 by either IHC or in-situ hybridization as defined by the ASCO / CAP Guidelines
• ≤ 15 brain metastases eligible for stereotactic radiation
• Able to swallow oral medications
• Willing to comply with all study procedures and available for duration of the study
• Measurable brain disease per RANO-BM criteria that can be measured in at least one dimension as ≥ 0.5 cm for both intact brain metastases and post-operative cavities

Inclusion criteria as written on the registry, trimmed. The full list, with exclusions, is on the live record.