Purpose: Neutropenia is the most common toxicity of CDK4/6 inhibitors, causing frequent dose interruptions. However, CDK4/6 inhibitor-induced neutropenia shows a benign clinical course in contrast to that caused by chemotherapy. Here, we investigated the safety of a new dose scheme for palbociclib, which avoids dose delays or reductions due to afebrile grade 3 neutropenia. Methods: A consecutive cohort of ER(+)/HER2(−) advanced breast cancer patients who received palbociclib between 2017 and 2018 was analyzed. The patients were classified into Group 1 (patients who maintained palbociclib dose with afebrile grade 3 neutropenia), Group 2 (patients who experienced any dose modification with afebrile grade 3 neutropenia), and Group 3 (patients without afebrile grade 3 neutropenia). The primary endpoint was febrile neutropenia incidence; other toxicities were compared with those of the PALOMA-2 trial. Results: Among the 107 patients, 54.2%, 22.4%, and 23.4% were classified into Groups 1, 2, and 3, respectively. There was no febrile neutropenia in Groups 1 and 2 during palbociclib treatment. Group 1 showed higher incidence of thrombocytopenia (all-grade, 32.8%; grade 3–4, 8.6%) than Group 2 and the PALOMA-2 data, but there was no bleeding related to thrombocytopenia. Group 1 showed higher incidence of all-grade non-hematologic adverse events than Group 2; only one grade 3 non-hematologic toxicity was observed in Group 1. There were no treatment-related hospitalizations or deaths in Group 1. Conclusions: Thus, omitting palbociclib dose modification with afebrile grade 3 neutropenia is safe and tolerable without febrile neutropenia events. This scheme could be useful to avoid unnecessary reductions in palbociclib doses in future practice.
|Number of pages||10|
|Journal||Breast Cancer Research and Treatment|
|Publication status||Published - 2020 Aug 1|
Bibliographical noteFunding Information:
This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (Grant Number: HI19C0430).
© 2020, Springer Science+Business Media, LLC, part of Springer Nature.
All Science Journal Classification (ASJC) codes
- Cancer Research