Real-world progression-free survival and overall survival of palbociclib plus endocrine therapy (ET) in Japanese patients with hormone receptor-positive/human epidermal growth factor receptor 2-negative advanced breast cancer in the first-line or second-line setting: an observational study

• Published in: Breast cancer (Tokyo, Japan) Vol. 31; no. 4; pp. 621 - 632
• Main Authors: Yoshinami, Tetsuhiro, Nagai, Shigenori E., Hattori, Masaya, Okamura, Takuho, Watanabe, Kenichi, Nakayama, Takahiro, Masuda, Hiroko, Tsuneizumi, Michiko, Takabatake, Daisuke, Harao, Michiko, Yoshino, Hiroshi, Mori, Natsuko, Yasojima, Hiroyuki, Oshiro, Chiya, Iwase, Madoka, Yamaguchi, Miki, Sangai, Takafumi, Kosaka, Nobuyoshi, Tajima, Kentaro, Masuda, Norikazu
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01-07-2024
• Subjects: Cancer Research; Medicine; Medicine & Public Health; Oncology; Original; Original Article; Surgery; Surgical Oncology; Advanced breast cancer; CDK4/6 inhibitors; Palbociclib; Real-world evidence
• ISSN: 1340-6868; 1880-4233; 1880-4233
• DOI: 10.1007/s12282-024-01575-5

Background
A recent large real-world study conducted in the United States reported the effectiveness of palbociclib plus aromatase inhibitor in HR+/HER2− advanced breast cancer (ABC). However, local clinical practice and available medical treatment can vary between Japan and Western countries. Thus, it is important to investigate Japanese real-world data. This observational, multicenter study (NCT05399329) reports the interim analysis of effectiveness of palbociclib plus ET as first-line or second-line treatment for HR+/HER2− ABC by estimating real-world progression-free survival (rwPFS) and overall survival (OS) in Japanese routine clinical practice.
Methods
Real-world clinical outcomes and treatment patterns of palbociclib plus ET were captured using a medical record review of patients diagnosed with HR+/HER2− ABC who had received palbociclib plus ET in the first-line or second-line treatment across 20 sites in Japan. The primary endpoint was rwPFS; secondary endpoints were OS, real-world overall response rate, real-world clinical benefit rate, and chemotherapy-free survival.
Results
Of the 677 eligible patients, 420 and 257 patients, respectively, had received palbociclib with ET as first-line and second-line treatments. Median rwPFS (95% confidence interval) was 24.5 months (19.9–29.4) for first-line and 14.5 months (10.2–19.0) for second-line treatment groups. Median OS was not reached in the first-line group and was 46.7 months (38.8-not estimated) for the second-line group. The 36-month OS rates for de novo metastasis, treatment-free interval (TFI) ≥ 12 months, and TFI < 12 months were 80.2% (69.1–87.7), 82.0% (70.7–89.3), and 66.0% (57.9–72.9), respectively.
Conclusion
The addition of palbociclib to ET was effective for treating HR+/HER2− ABC in Japanese routine clinical practice.