Real-world treatment patterns of subsequent therapy after palbociclib in patients with advanced breast cancer in Japan

• Published in: Breast (Edinburgh) Vol. 70; pp. 1 - 7
• Main Authors: Sawaki, Masataka, Muramatsu, Yasuaki, Togo, Kanae, Iwata, Hiroji
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.08.2023; Elsevier
• Subjects: And subsequent therapy; Antineoplastic Combined Chemotherapy Protocols - therapeutic use; Breast cancer; Breast Neoplasms - etiology; Cyclin-Dependent Kinase 4; Cyclin-dependent kinase 4/6 inhibitor; Endocrine therapy; Female; Humans; Japan; Original; Palbociclib; Piperazines; Protein Kinase Inhibitors - therapeutic use; Pyridines - therapeutic use; Real-world; Receptor, ErbB-2; Japan; Endocrine therapy; Breast cancer; And subsequent therapy; Palbociclib; Real-world; Cyclin-dependent kinase 4/6 inhibitor
• ISSN: 0960-9776; 1532-3080; 1532-3080
• DOI: 10.1016/j.breast.2023.05.006

The optimal treatment following endocrine therapy (ET) plus a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) has not been established. We aimed to investigate treatment patterns and time to treatment failure (TTF) of subsequent therapy after palbociclib in a Japanese real-world setting. This retrospective observational study used de-identified data of patients with advanced breast cancer treated with palbociclib, using a nationwide claims database (April 2008 to June 2021). Measures included the type of subsequent therapies after palbociclib (endocrine-based therapy: ET alone, ET + CDK4/6i, and ET + mammalian target of rapamycin inhibitor [mTORi]; chemotherapy; chemotherapy + ET; and others) and their TTFs. The median TTF and 95% confidence interval (CI) were estimated using the Kaplan-Meier method. Of 1170 patients treated with palbociclib, 224 and 235 received subsequent therapies after first- and second-line palbociclib treatment, respectively. Among them, 60.7% and 52.8% were treated with endocrine-based therapies as first subsequent therapy, including ET + CDK4/6i (31.2% and 29.8%, respectively). The median TTF (95% CI) of ET alone, ET + CDK4/6i, and ET + mTORi as first subsequent therapy after first-line palbociclib were 4.4 (2.8–13.7), 10.9 (6.5–15.6), and 6.1 (5.1–7.2) months, respectively. No apparent relationship between the treatment duration of prior ET + palbociclib and subsequent abemaciclib was observed. This real-world study revealed that one-third of the patients received sequential CDK4/6i after ET + palbociclib, and treatment duration of ET + CDK4/6i following ET + palbociclib was the longest among the treatment options. Further data are awaited to determine whether ET + targeted therapy with CDK4/6i and mTORi provides acceptable treatment options following ET + palbociclib. •No optimal treatments after endocrine therapy (ET) + cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) has been established.•This study investigated treatment patterns and treatment duration after palbociclib in a Japanese real-world setting (n = 1170).•More than 60% were treated with endocrine-based therapies after palbociclib, and one-thirds continued ET + CDK4/6i.•ET + CDK4/6i provided the longest treatment duration among treatment options.•ET + targeted therapy may provide acceptable treatment options after palbociclib.