A Phase II Study of Abemaciclib plus Trastuzumab versus Trastuzumab with Standard Chemotherapy in Patients with Advanced Breast Cancer

Full Title

I3Y-MC-JPBZ(a)/monarcHER: A Phase 2, Randomized, Multicenter, 3-Arm, Open-Label Study to Compare the Efficacy of Abemaciclib Plus Trastuzumab With or Without Fulvestrant to Standard-of-Care Chemotherapy of Physician’s Choice Plus Trastuzumab in Women with HR+, HER2+ Locally Advanced or Metastatic Breast Cancer


Women with hormone receptor-positive, HER2-positive advanced breast cancer may receive treatment with trastuzumab plus chemotherapy. In this study, researchers want to evaluate the safety and effectiveness of trastuzumab plus the newer drug abemaciclib. Abemaciclib is designed to inhibit cancer growth by blocking cyclin-dependent kinases (CDK), enzymes which cancer cells need to grow and divide.

Patients will be randomly assigned to receive one of three regimens: abemaciclib with trastuzumab and fulvestrant (a hormonal therapy); abemaciclib with trastuzumab; or trastuzumab with physician’s choice of standard chemotherapy. Abemaciclib is taken orally (by mouth), fulvestrant is given as an injection, and trastuzumab is given intravenously (by vein).


To be eligible for this study, patients must meet several criteria, including but not limited to the following:

  • Patients must have locally advanced inoperable breast cancer or metastatic breast cancer that is positive for hormone receptors and HER2.
  • Patients’ cancers must have continued to grow despite at least two prior regimens of treatment that target HER2 (including T-DM1) and also prior treatment with a taxane.
  • Patients must recover from the serious side effects of prior treatments before entering the study.
  • Patients must be physically well enough that they are fully ambulatory, capable of all self care, and are capable of all but physically strenuous activities. As an example, patients must be well enough that they would be able to carry out office work or light housework.
  • This study is for women age 18 and older.

For more information about this study and to inquire about eligibility, please contact Dr. Maura Dickler at 646-888-5456.







Troso-Sandoval, Tiffany, MD