Practice Update: Oncology

CONFERENCE COVERAGE 18

34 th Annual Miami Breast Cancer Conference 9–12 MARCH 2017 • MIAMI BEACH, FLORIDA, USA

“Lightning rounds” capped off an eventful 34th Annual Miami Breast Cancer Conference, providing a roundup of key sessions and take-aways for metastatic breast cancer presented at this year’s meeting. The PracticeUpdate Editorial Team reports fromMiami Beach.

CDK4/6 inhibitors in hormone receptor-positive, HER2-negative metastatic breast cancer CDK4/6 inhibitors should be offered as first-line treatment for ER+, HER2-negative breast cancer patients since they significantly increase the time to progression when they are combined with endocrine therapy.

T his was the conclusion of a talk on CDK 4/6 inhibitors in ER+ HER2-negative metastatic breast cancer at the 34th Miami Breast Cancer Conference. Kimberly L. Blackwell, MD of Duke University Medical Center, Durham, North Carolina explained that CDK4/6 inhibitors com- bined with endocrine therapy have shown improvements in progression free survival. Dr Blackwell began by reviewing the mechanism of action of CDK4/6 inhibitors and their interaction with cyclin D1 to phos- phorylate the retinoblastoma tumor suppressor gene. Dr Blackwell referred to the clinical trials that led to the FDA approval of palbociclib for patients with ER+ metastatic breast cancer. PALOMA-1 is the phase II pivotal trial of palbociclib in combina- tion with letrozole in first-line treatment of ER+ metastatic breast

cancer that showed a 10-month improvement with the combina- tion. The confirmatory PALOMA-2 trial was a phase 3 randomized study that enrolled 666 postmenopausal patients with ER+ meta- static breast cancer and no prior treatment for advanced disease to received either palbociclib in combination with letrozole or placebo in combination with letrozole. This trial showed that the palbociclib-letrozole group had a 10.3-month improvement in pro- gression free survival compared to the placebo-letrozole group with a hazard ratio of 0.58 that was statistical significant. Finally, PALOMA-3 compared fulvestrant plus palbociclib versus fulves- trant plus placebo in patients with hormone receptor positive metastatic breast cancer that progressed on previous endocrine therapy. The combination doubled progression free survival. Ribociclib is the other CDK4/6 inhibitor that has shown to improve progression free survival in combination with letrozole.

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