Prof Richard Finn (University of California, Los Angeles, USA) chairs an expert discussion on the latest in CDK inhibition in breast cancer for ecancertv at SABCS 2016 in San Antonio with Professor Michael Gnant (Medizinischen Universität Wien, Vienna, Austria), Dr Mark Harries (Guy’s & St Thomas’ Hospitals NHS Foundation Trust, UK) and Prof Sandra Swain (Georgetown University Medical Center, Washington, DC, USA)

15 years after the Nobel Prize in Physiology was awarded for the identification of the role of CDK in regulating the cell cycle, 2016 has seen some of the most exciting advances for the actual and potential clinical utility of this research for breast cancer patients.

The panel first discussed Phase III data from this year, including the ribociclib MONALEESA-2 trial and the ‘stunning’ results seen for palbociclib in the PALOMA-2 and PALOMA-3 trials.

With regards to the toxicity profiles even though neutropenia was noted, it was suggested that these treatments remain a ‘paradigm shift’, as some patients remain on treatment for ‘10 months longer than endocrine therapy’. 

Another treatment looking at CDK 4/6 inhibition is abemaciclib, which has been shown to cause less neutropenia than the other treatments, but increased diarrhoea.

The panel suggest this could be due to the increased activity against CDK4 and therefore gastrointestinal issues.

The international panel confirmed that the optimism for the use of these treatments was seen in both US and Europe, due to the ‘magnitude of benefit’ seen.

Some unresolved questions were posed, such as how the treatments are being sequenced and the use of them in the early breast cancer setting.

Hoping to help answer this question is the PALLAS trial, which is evaluating the addition of 2 years of palbociclib to standard adjuvant endocrine therapy for patients with HR / HER2- early breast cancer (EBC).

The panel then briefly touched on biomarkers, the use of CDK 4/6 inhibitors outside of ER BC, and the strength of PFS and time to chemotherapy as endpoints verses OS.

It is clear that the significance of CDK 4/6 inhibition in breast cancer will continue to grow, with the importance of continuing medical education highlighted so that this breakthrough in the treatment of breast cancer can be appropriately managed.

Supported by a grant from Pfizer Inc.