A nationwide real-world study for evaluation of effectiveness and safety of T-DM1 in patients with HER2-positive metastatic breast cancer in Korea (KCSG BR19-15)

• Published in: Therapeutic advances in medical oncology 2024-01, Vol.16, p.17588359231225029
• Main Authors: Baek, Sun Kyung, Jeong, Jae-Ho, Jung, KyungHae, Ahn, Hee Kyung, Kim, Min Hwan, Sohn, Joohyuk, Park, In Hae, Ahn, Jin Seok, Lee, Dae-Won, Im, Seock-Ah, Sim, Sung Hoon, Lee, Keun Seok, Hyun Kim, Jee, Shim, Hyun-Jeong, Chae, Yeesoo, Koh, Su-Jin, Lee, Hyorak, Lee, Jieun, Byun, Jae-Ho, Seol, Youngmi, Lee, Eun Mi, Jee, Hee-Jung, An, Hyonggin, Park, Eun Byeol, Suh, Young Ju, Lee, Kyoung Eun, Park, Yeon Hee
• Format: Article
• Language: English
• Subjects: Original Research
• ISSN: 1758-8340; 1758-8359; 1758-8359
• DOI: 10.1177/17588359231225029

This study aimed to investigate clinical practices and factors related to the outcomes of T-DM1 use in patients with HER2-positive metastatic breast cancer (mBC). We included patients with HER2-positive mBC who received T-DM1 as a palliative therapy between August 2017 and December 2018. The safety and outcomes of T-DM1, including overall response rate (ORR), progression-free survival (PFS), and overall survival (OS), were evaluated. A Cox proportional hazards model was used to estimate the hazard ratio and 95% confidence interval (CI) for mortality or progression to HER2-positive mBC. In total, 824 patients were enrolled during the study period. The mean age of patients was 58 years, and 516 (62.6%) patients relapsed after curative treatment. Excluding a history of endocrine therapy, 341 (41.4%) patients previously received none or first-line chemotherapy, 179 (21.7%) received second-line therapy, and 303 (36.9%) received third-or later-line chemotherapy before T-DM1 therapy. During a median follow-up of 16.8 months, the ORR was 35%, the median PFS was 6.6 months, and the median OS was not reached. The clinical factors associated with the hazard of progression were age (