Real-world data affirms palbociclib–AI combo efficacy in metastatic breast cancer

The use of the combination of palbociclib plus an aromatase inhibitor (AI) in the first-line treatment setting appears to confer survival advantage on patients with hormone receptor–positive/human epidermal growth factor receptor 2–negative (HR+/HER2−) metastatic breast cancer (MBC), according to real-world data.

The study used data from the Flatiron Health Analytic Database and included 2,888 patients who initiated treatment with first-line palbociclib plus an AI (combination) vs an AI alone (monotherapy) in routine US clinical practice.

The combination group were more likely to have an Eastern Cooperative Oncology Group (ECOG) performance status of 0, de novo MBC, a lower mean comorbidity score, and a higher number of metastatic sites than the monotherapy group. Patient characteristics were generally balanced following stabilized inverse probability treatment weighting (sIPTW) and between propensity score-matched groups.

After sIPTW, the median age of patients in both treatment groups was 70 years, and most patients (~68 percent) were White and about 30 percent had visceral disease. The median duration of follow-up was 23.9 months in the combination group and 24.5 months in the monotherapy group.

Compared with monotherapy, combination therapy yielded a significantly longer overall survival (median, 49.1 vs 43.2 months; hazard ratio [HR], 0.76, 95 percent confidence interval [CI], 0.65–0.87; p<0.0001) as well as progression-free survival (median, 19.3 vs 13.9 months; HR, 0.70, 95 percent CI, 0.62–0.78; p<0.0001).