Measures of functional status in older patients treated with palbociclib for advanced breast cancer

Introduction: Limited data are available on the effects of treatment for advanced breast cancer (ABC) in older patients because this population has limited enrollment in clinical trials. Data generated from the prospective, noninterventional POLARIS study of patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative ABC may help bridge the gap in our understanding of the tolerability and outcomes in this vulnerable population.

Materials and methods: We evaluated measures of geriatric impairments and activities of daily living in patients with ABC aged ≥70 years in POLARIS to evaluate the change within six months of palbociclib initiation. Geriatric impairments and activities of daily living (functional) status were assessed using the Geriatric 8 (G8) and Activities of Daily Living (ADL) screening tools. The G8, ADL, and Eastern Cooperative Oncology Group performance status (ECOG PS) scores were assessed at baseline and month six through end of treatment with palbociclib. ECOG PS scores were also stratified by G8 and ADL score severity subgroups (G8: ≤14 = impaired subgroup; >14 = not at all impaired subgroup; ADL: <18 = dependent subgroup, 18 = independent subgroup).

Results: At data cutoff in November 2020, of 1282 POLARIS patients of all ages, 287 (22.4%) were ≥ 70 years old and completed ≥6 months of palbociclib therapy. At baseline, 117 (45%; n = 260) of these patients had an ECOG PS score of 0, 143 (55%; n = 260) had ECOG PS score > 0, 248 (86%) had G8 scores (mean [SD] 13.6 [2.14]), and 256 (89%) had ADL scores (17.7 [1.03]) among the available 287 patients. At six months, 102 (40%; n = 255) had an ECOG PS score of 0, 153 (60%; n = 255) had ECOG PS score > 0, 198 (69%) had G8 scores (13.6 [1.99]), and 211 (74%) had ADL scores (17.6 [1.22]) among the 287 available patients. There was no mean change (standard deviation) from baseline to 6 months in mean ECOG PS scores (0.0 [0.61], P = 0.24), G8 scores (0.0 [2.17], P = 0.89), or ADL scores (0.0 [1.00], P = 0.62).

Discussion: In this subgroup analysis of older patients with ABC from POLARIS, functional status and impairment outcomes were preserved in older patients receiving palbociclib. G8, ADL, and ECOG PS scores were generally maintained during the first six months of palbociclib therapy.

Clinicaltrials: govidentification number. NCT03280303.