The phase 3 PALOMA-3 study was designed to evaluate the efficacy of palbociclib (a cyclin-dependent kinase 4/6 inhibitor) plus fulvestrant (a complete estrogen receptor antagonist) compared with treatment with fulvestrant alone in patients with advanced hormone receptor–positive/human epidermal growth factor receptor 2–negative breast cancer. As a secondary end point, patient-reported general health status was also captured and evaluated in this analysis.
Patient-reported outcomes were assessed using EQ-5D, a standardized measure of health status that consists of a descriptive system comprising 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression rated at 3 levels (no, some, or extreme problems) and a single index score for health status (range, 0 [dead] to 1 [full health]) calculated using a standard algorithm. Assessments were made at baseline, on day 1 of each cycle until cycle 4, and every alternate cycle from cycle 6 until end of treatment. Additionally, a visual analog scale (VAS) measured self-rated health status from ‘0’ (worst imaginable) to ‘100’ (best imaginable). A repeated-measures, mixed-effects model was used to compare overall index and VAS scores between treatments, controlling for baseline.
Patients were randomized 2:1 to receive palbociclib plus fulvestrant (n = 347) or placebo plus fulvestrant (n = 174); completion rates, defined as completing all questions at baseline, were ≥95% for each group. The mean (SD) scores at baseline were comparable between palbociclib plus fulvestrant and fulvestrant alone for the VAS (72.9 [17.22] vs 70.3 [19.87]) and the EQ-5D index scores (0.73 [0.23] vs 0.71 [0.23]). General health status assessed by VAS was maintained from baseline, and no significant difference in overall EQ-5D VAS scores was observed between treatment arms. The proportion of patients reporting the presence of a problem at baseline was similar for palbociclib plus fulvestrant and fulvestrant, respectively: mobility (28% vs 32%), self-care (9% vs 9%), usual activities (38% vs 45%), pain (67% vs 67%), and anxiety/depression (52% vs 61%). The overall mean EQ-5D index scores during treatment were significantly greater (P <0.05) for palbociclib plus fulvestrant (0.74) compared with fulvestrant alone (0.69).
Overall, the addition of palbociclib to fulvestrant was associated with significantly higher on treatment EQ-5D index scores compared with fulvestrant alone. General health status, as assessed by VAS scores, was maintained over the course of therapy, and no significant differences were seen between treatment arms despite the longer duration of treatment in the palbociclib plus fulvestrant arm compared with the fulvestrant arm.