Overall survival in Japanese patients with ER+/HER2− advanced breast cancer treated with first-line palbociclib plus letrozole

Abstract

Background An open-label, single-arm, Japanese phase 2 study (J-Ph2) investigated the efficacy and safety of first-line (1L) palbociclib (PAL) + letrozole (LET) in postmenopausal Japanese women with ER+/HER2− advanced breast cancer (ABC). In the final analysis, median progression-free survival was 35.7 months (95% CI 21.7–46.7); but overall survival (OS) data were immature. Here, we report the findings from a follow-up study of J-Ph2 (NCT04735367) evaluating OS and subsequent therapy in these Japanese women. Methods Patients (N = 42) who participated in J-Ph2 were enrolled in the OS follow-up study. The primary endpoint was OS and secondary endpoints included type and duration of subsequent therapy. Results Patients were a median age of 62.5 years; 48% had visceral metastases. At a median follow-up of 89.7 months, the median OS was 85.4 months (95% CI 64.3–not estimable). Median OS was longer in patients with nonvisceral versus visceral metastases (not reached vs 67.3 months), or with treatment-free interval > 12 months versus ≤ 12 months (85.4 vs 45.4 months), or with treatment duration ≥ 24 months versus < 24 months (not reached vs 47.5 months). Of patients who received a first subsequent therapy (81%), most (67%) continued endocrine-based therapy, while 7% received chemotherapy. The median duration of the first subsequent therapy was 8.3 months (95% CI 3.9–12.2), and the median chemotherapy-free survival was 69.1 months (95% CI 24.2–85.4). Conclusions In this population of Japanese women with ER+/HER2− ABC, median OS was over 7 years with 1L PAL + LET, supporting the use of 1L PAL + endocrine therapy. Trial number NCT04735367.

Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy (ET) in Japanese patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer in the first-line or second-line setting: an observational study

“…The safety and efficacy of palbociclib were investigated in two phase 3, randomized clinical trials (RCTs), PALOMA-2 (palbociclib plus letrozole vs placebo plus letrozole as first-line therapy [ 8 ] and PALOMA-3 (palbociclib plus fulvestrant or placebo plus fulvestrant as second-line or greater lines) [ 9 ]. Palbociclib plus ET significantly improved progression-free survival (PFS) compared to placebo in both studies, however, no statistically significant differences were observed in the overall survival (OS) [ 9 – 12 ] In Japanese patients with HR+/HER2− ABC ( n = 42), a phase 2, single-arm, open-label study of palbociclib in combination with letrozole as first-line treatment demonstrated that the median PFS was 35.7 months with a manageable safety profile [ 13 ], and at a median follow-up of 89.7 months, the median OS was 85.4 months [ 14 ].…”