• Hirofumi Mukai, Chikako Shimizu, Norikazu Masuda, Shoichiro Ohtani, Shinji Ohno, Masato Takahashi, Yutaka Yamamoto, Reiki Nishimura, Nobuaki Sato, Shozo Ohsumi, Hiroji Iwata, Yuko Mori, Satoshi Hashigaki, Yasuaki Muramatsu, Takashi Nagasawa, Yoshiko Umeyama, Dongrui R Lu, and Masakazu Toi.
• Division of Breast and Medical Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa-shi, Chiba, 277-8577, Japan. hrmukai@east.ncc.go.jp.
• Int. J. Clin. Oncol. 2019 Mar 1; 24 (3): 274-287.

BackgroundIn PALOMA-2, palbociclib-letrozole significantly improved progression-free survival (PFS) vs placebo-letrozole in women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2-) advanced breast cancer (ABC) in the first-line setting. We evaluated the efficacy, safety, and pharmacokinetics of palbociclib in Japanese women in PALOMA-2.MethodsIn this phase 3 study, 666 postmenopausal women with ER+/HER2- ABC were randomized 2:1 to palbociclib (125 mg/day [3 weeks on/1 week off]) plus letrozole (2.5 mg daily) or placebo plus letrozole. A prespecified, exploratory, subgroup analysis of Japanese patients (n = 46) was conducted to compare results with those of the overall population.ResultsAt the February 26, 2016 cutoff, median PFS among the 46 Japanese patients was 22.2 months (95%CI, 13.6‒not estimable) with palbociclib-letrozole vs 13.8 months (5.6‒22.2) with placebo-letrozole (hazard ratio, 0.59 [95%CI, 0.26-1.34]). The most common adverse events (AEs) were hematologic and more frequent among Japanese patients than the overall population (neutropenia: 93.8% [87.5% grade 3/4] vs 79.5% [66.4%]; leukopenia: 62.5% [43.8%] vs 39.0% [24.8%]); no Japanese patients had febrile neutropenia. Palbociclib dose reductions due to toxicity (mainly neutropenia) were more common in Japanese patients (62.5% vs 36.0%); few permanently discontinued due to AEs. Although mean palbociclib trough concentration was higher in Japanese patients vs non-Asians (95.4 vs 61.7 ng/mL), the range of individual values of the Japanese patients was within that of non-Asians.ConclusionsThese results from PALOMA-2 suggest that palbociclib-letrozole merits consideration as a first-line treatment option for postmenopausal Japanese patients with ER+/HER2‒ ABC. ClinicalTrials.gov: NCT01740427.

35 keywords...

hide…