Real-world effectiveness of palbociclib plus an aromatase inhibitor in HR+/HER2- MBC patients living in disadvantaged neighborhoods.

Palbociclib (PAL) combined with endocrine therapy (ET) is approved for hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2- ) advanced/metastatic breast cancer (MBC). However, there is limited data on the effectiveness of PAL + ET in patients with MBC and low socioeconomic status. This retrospective study of the Flatiron Health database compared overall survival (OS) and real-world progression-free survival (rwPFS) in patients with MBC living in disadvantaged neighborhoods who received either first-line PAL with an aromatase inhibitor (AI) or an AI alone. Of 723 patients, 394 received PAL + AI and 329 received AI alone. After stabilized inverse probability of treatment weighting, median OS was 57.1 months versus 38.2 months (hazard ratio, 0.70, P = 0.0053) and median rwPFS was 19.1 months versus 14.0 months (hazard ratio, 0.66, P = 0.0007) for PAL + AI versus AI alone, respectively. This real-world data analysis demonstrated that first-line PAL + AI versus AI alone was associated with survival benefit in patients with HR+/HER2- MBC living in disadvantaged neighborhoods. Trial registration number: NCT06495164.