Adjuvant Everolimus and CDK4/6 Trials in Breast Cancer

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The Southwest Oncology Group (SWOG) 1207 study is an ongoing clinical trial evaluating adjuvant everolimus in high-risk individuals with node-negative and node-positive breast cancer, Eleftherios Mamounas, MD, describes. After more than 2 years of recruitment, the study has not yet reached its target enrollment goal of 3500 participants. The study is not recruiting patients as efficiently as expected, Mamounas notes, likely due to the study’s design. SWOG may loosen eligibility criteria to improve trial accrual. There is a great deal of interest in the results from this study, adds Hope S. Rugo, MD.

Palbociclib is a selective inhibitor of cyclin-dependent kinases, CDK4 and CDK6, and is the first drug in its class, says Sara Hurvitz, MD. In the open-label phase II PALOMA-1 study, treatment with palbociclib plus letrozole demonstrated a median progression-free survival (PFS) of 20.2 months compared with 10.2 months with letrozole alone (HR = 0.488; P = .0004). These results led to an accelerated approval for the drug on February 3, 2015.

Hurvitz notes that such a large benefit was not expected when the study was initiated, particularly since it was a phase II analysis. The main side effect is dose-limiting neutropenia, which she suggests is more favorable than the toxicities experienced with mTOR inhibitors.

Phase III data from the first-line PALOMA-2 trial is anticipated. Additionally, other studies are also exploring CDK4/6 inhibition in breast cancer, including PALOMA-3, MONALEESA-2, and PENELOPE. Dialecti Voudouris, MD, encourages all of her patients to enroll in clinical trials. Additionally, expanded access programs assists community oncologists in enrolling patients.