Abstract
BackgroundIn the double-blind, phase 3 PALOMA-3 study, palbociclib–fulvestrant significantly prolonged progression-free survival versus placebo–fulvestrant in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) metastatic breast cancer (MBC) whose disease had progressed on prior endocrine therapy. The present study evaluated the efficacy, safety, and pharmacokinetics of palbociclib plus fulvestrant in Japanese patients enrolled in PALOMA-3.MethodsPre/peri/postmenopausal women with HR+/HER2– MBC were randomized 2:1 to fulvestrant (500 mg) and either palbociclib (125 mg/day; 3 weeks on/1 week off; n = 347) or placebo (n = 174). Prespecified exploratory analyses compared the efficacy (data cutoff: October 23, 2015), safety, and pharmacokinetics (data cutoff: December 5, 2014) in Japanese women versus the overall population.ResultsA total of 35 Japanese women were randomized to palbociclib–fulvestrant (n = 27) or placebo–fulvestrant (n = 8). Median progression-free survival was 13.6 months (95% CI, 7.5–not estimable) in the Japanese palbociclib–fulvestrant group and 11.2 months (95% CI, 5.6–not estimable) in the placebo–fulvestrant group. The most common adverse event (AE) in Japanese patients was neutropenia (all grades, 93%); no discontinuations were due to an AE. Geometric mean trough concentration values (within-subject mean steady state) for palbociclib were similar for Japanese Asian (excluding Japanese), and non-Asian patients (84.4 ng/mL, 86.3 ng/mL, and 74.8 ng/mL, respectively).Conclusion(s)The results for the overall population and Japanese patients in PALOMA-3 suggest that palbociclib plus fulvestrant was effective and well tolerated in Japanese patients with HR+/HER2‒ MBC whose disease had progressed on prior endocrine therapy (Pfizer; NCT01942135).
Highlights
Breast cancer is the most common cancer in women worldwide and the second leading cause of cancer-related death in Asian women [1]
We conducted prespecified exploratory analyses of the PALOMA-3 trial to evaluate the efficacy, safety, and pharmacokinetics of palbociclib–fulvestrant versus placebo–fulvestrant in premenopausal and postmenopausal Japanese patients with HR+/HER2– metastatic breast cancer (MBC) whose disease had progressed on prior endocrine therapy
The primary reason for this exploratory analysis was to evaluate the efficacy, safety, and pharmacokinetics of palbociclib in Japanese patients enrolled in the PALOMA-3 study and to determine whether racial differences affected the efficacy and safety of palbociclib therapy in these patients
Summary
Breast cancer is the most common cancer in women worldwide and the second leading cause of cancer-related death in Asian women [1]. Palbociclib has been approved in the United States, the European Union, and Japan for the treatment of HR+/HER2– advanced or metastatic breast cancer in combination with endocrine therapy [7,8,9]. In the double-blind, phase 3 PALOMA-3 study, palbociclib–fulvestrant significantly prolonged progressionfree survival versus placebo–fulvestrant in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2–) metastatic breast cancer (MBC) whose disease had progressed on prior endocrine therapy. The present study evaluated the efficacy, safety, and pharmacokinetics of palbociclib plus fulvestrant in Japanese patients enrolled in PALOMA-3. Conclusion(s) The results for the overall population and Japanese patients in PALOMA-3 suggest that palbociclib plus fulvestrant was effective and well tolerated in Japanese patients with HR+/HER2‒ MBC whose disease had progressed on prior endocrine therapy (Pfizer; NCT01942135)
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