Factors associated with prolonged time to treatment failure with fulvestrant 500 mg in patients with post-menopausal estrogen receptor-positive advanced breast cancer: a sub-group analysis of the JBCRG-C06 Safari study

Abstract

Objective: The JBCRG-C06 Safari study showed that earlier fulvestrant 500 mg (F500) use, a longer time from diagnosis to F500 use, and no prior palliative chemotherapy were associated with significantly longer time to treatment failure (TTF) among Japanese patients with estrogen receptor-positive (ER+) advanced breast cancer (ABC). The objective of this sub-group analysis was to further examine data from the Safari study, focusing on ER + and human epidermal growth factor receptor-negative (HER2−) cases.

Methods: The Safari study (UMIN000015168) was a retrospective, multi-center cohort study, conducted in 1,072 patients in Japan taking F500 for ER + ABC. The sub-analysis included only patients administered F500 as second-line or later therapy (n = 960). Of these, 828 patients were HER2−.

Results Multivariate analysis showed that advanced age (≥65 years; p = .035), longer time (≥3 years) from ABC diagnosis to F500 use (p < .001), no prior chemotherapy (p < .001), and F500 treatment line (p < .001) were correlated with prolonged TTF (median = 5.39 months).

Conclusions: In ER+/HER2− patients receiving F500 as a second-line or later therapy, treatment line, advanced age, no prior palliative chemotherapy use, and a longer period from ABC diagnosis to F500 use were associated with longer TTF.

Keywords:

• Breast cancer
• anti-neoplastic agents
• post-menopause
• hormones
• female
• treatment failure

Transparency

Declaration of funding

Funding for this study was provided by the Japan Breast Cancer Research Group (JBCRG), a study group that also participated in the conduct of the study, and AstraZeneca.

Declaration of financial/other relationships

H. Kawaguchi received consultancy/advisory fees from AstraZeneca and Chugai; and speakers’ bureau fees from Chugai, AstraZeneca, Kyowa Kirin, Novartis, and Taiho. N. Masuda received honoraria from Chugai and AstraZeneca. T. Nakayama received speakers’ bureau fees from Chugai, AstraZeneca, and Novartis. K. Anan received honoraria from Chugai Pharmaceutical Co., Ltd., AstraZeneca K.K., Eisai Co., and Novartis Pharma K.K. Y. Ito received grants/research fees from Novartis, MSD, AstraZeneca, Parexel, Chugai, and Lilly. N. Sato received speakers’ bureau fees from AstraZeneca K.K., Chugai Pharmaceutical Co., Ltd., Eisai Co., Ltd., and Taiho Pharmaceutical Co., Ltd. S. Saji received grants/research and speakers’ bureau fees from AstraZeneca. T. Takano received grants/research fees from Chugai, Takeda, and Novartis. S. Nakamura received honoraria from AstraZeneca. S. Morita received speakers’ bureau fees from AstraZeneca. T. Yamashita received honoraria from Chugai and Eisai. S. Ohno received speakers’ bureau fees from AstraZeneca and Novartis. K. Aogi, S. Ohtani, E. Tokunaga, Y. Hasegawa, M. Hattori, T. Fujisawa, M. Yamaguchi, H. Yamashita, Y. Yamamoto, D. Yotsumoto, and M. Toi have no financial or other relationships to declare. Peer reviewers on this manuscript have received an honorarium from CMRO for their review work, but have no other relevant financial relationships to disclose.

Acknowledgments

We thank the patients who participated in this study. We appreciate the contribution of data entry assistance from AC Medical INC, and the contribution of the Japan Breast Cancer Research Group (JBCRG) administrative office and IBEC Co., Ltd. to the management of the study. The authors would also like to acknowledge Emma Donadieu and Marion Barnett of Edanz Medical Writing for medical writing support, which was funded by AstraZeneca.