Dr. Tripathy on Combination Strategies With CDK4/6 Inhibitors in Breast Cancer

Debu Tripathy, MD, professor and chairman, Department of Breast Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses combination strategies being investigated with CDK4/6 inhibitors in breast cancer.

Many investigational strategies are being tested with these combinations, though very few have been reported out, Tripathy explains. Results of a small phase I study investigated the combination of everolimus (Afinitor) with ribociclib (Kisqali) from the TRINITI-1 study, which did show a median progression-free survival (PFS) of approximately 4 months.

Tripathy says physicians need to be cognizant that patients who progress very early on therapy may differ from those who progress later. Patients who relapse within the first 6 to 8 months may have intrinsic resistance and could vary biologically, he adds.

Another combination being evaluated is in patients with metastatic HER2-positive breast cancer who received induction treatment with chemotherapy and trastuzumab (Herceptin)/pertuzumab (Perjeta). These patients are being randomized to receive palbociclib (Ibrance) or standard therapy, and PFS will be a key endpoint.

Additionally, CDK4/6 inhibition does seem to stimulate certain aspects of the immune system, Tripathy concludes. Researchers are exploring the combination of abemaciclib (Verzenio) with pembrolizumab (Keytruda) in clinical trials, which have shown promising early data.

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