At AACR this weekend, Dr Richard Finn (UCLA) presented the much anticipated front-line phase II data for Pfizer’s CDK4/6 inhibitor, palbociclib (palbo) plus letrozole versus letrozole alone in ER+ HER2- breast cancer.
The PALOMA series of trials are designed to show that adding a specific CDK inhibitor to an aromatase inhibitor enhances efficacy and improves outcomes.
There are three metastatic breast cancer trials in all, with PALOMA–1 being the phase II study while PALOMA–2 and –3 are phase III randomised controlled registration studies aimed at confirming the initial phase II results in combination with letrozole and fulvestrant, respectively. In addition, palbociclib is also being evaluated in combination with standard endocrine therapy (PENELOPE-B) for certain early-stage breast cancers.
In short, an analysis demonstrated that the primary endpoint of progression free survival (PFS) was met, but the overall survival (OS) data was not significant at the time of the analysis.
What does this does this data mean and in what context should we look at the results?