2018 年 26 巻 2 号 p. 105-109
Background: Palbociclib is reported to improve progression-free survival (PFS) in patients with estrogen-receptor (ER)-positive, human epidermal growth factor 2 (HER2)-negative metastatic breast cancer (MBC). However, evidence of the effects of palbociclib in heavily treated patients is limited. The present study aimed to determine the effects and toxicity of palbociclib in heavily pretreated patients and to find the differences between the patients treated with palbociclib in upfront line and those with in later-line.
Methods: This retrospective, single-center, observational study enrolled 26 patients with ER-positive, HER2-negative MBC who started palbociclib (125 mg) plus endocrine therapy between December 2017 and July 2018. These patients were divided into 2 groups, upfront (<3) and later-line groups (≥4 lines prior therapy). Progression-free survival (PFS) estimated using the Kaplan-Meier method was compared between 14 patients who received upfront-line therapy and 12 who received later-line therapy.
Results: Among the 26 patients, 22 (85%) had visceral metastasis. The median number of prior treatment lines for MBC was 3.5 and the median follow-up was 5.1 months. Median PFS was 3.6 months in later-line group, and PFS was significantly shorter than in the upfront-line group (p = 0.046, median PFS: not reached in upfront line group). The incidences of grade 3/4 neutropenia were 86% and 83% in the upfront- and later-line groups, respectively. One patient developed febrile neutropenia. The treatment schedule was interrupted in 13 (93%) and 11 (92%) patients in the upfront- and later-line groups, respectively. The number of the patients who required dose reduction was higher in later-line group than upfront-line group (67% vs. 57%).
Conclusion: Although the toxicity of palbociclib is tolerable with a low incidence of febrile neutropenia, palbociclib is less-effective for heavily pretreated patients in comparison with lightly-pretreated patients. Our findings indicated that palbociclib could be used as a front-line treatment for MBC.
