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M 22: Trends in Endpoint Selection in Clinical Trials of Advanced Breast Cancer

Poster Presenter

      Seung Yeon Song

      • PhD candidate
      • Chung-Ang University College of Pharmacy
        Korea, Republic of


This study aims to evaluate endpoint selection and its shift in trends in phase II and phase III trials of advanced breast cancer treatment.


All phase II and III advanced breast cancer clinical trials registered in registry between Oct 2000 and Sep 2012 were included (Cohort A: Oct 2000 to Sep 2007; Cohort B: Oct 2007 to Sep 2012). Primary and secondary outcome measures as well as trial characteristics were extracted. Co-authors: Hyangki Lee, Gyungjin Kim and Ji Hee Yun; Department of Pharmaceutical Industry management, Graduate School, Chung-Ang University, Seoul, Korea; Eun Young Kim, Department of Health, Social and Clinical Pharmacy, Chung-Ang University College of Pharmacy, Seoul, Korea


Of 398 phase II and 120 phase III trials, the most frequently intended primary endpoint was progression-free survival in both phase types (phase II: 28.1%; phase III: 50.0%). For phase II trials, a shifting trend in primary outcome was observed from cohort A to cohort B: use of objective response rate, the most frequently intended primary outcome, significantly declined (cohort A: 60.6%; cohort B: 39.0%; P <.001); while use of progression-free survival significantly increased (cohort A: 17.6%; cohort B: 40.7%; P <.001). For phase III trials, PFS was the most frequently used primary outcome in both cohort groups with a statistically significant increase in frequency (cohort A: 35.9%; cohort B: 66.1%, P < .05). The proportions of trials using each outcome measure also differed by intervention types. For phase II, trials with chemotherpy-only intervention used objective response rate with a relatively higher frequency while those with targeted and/or hormone therapy intervention used progression-free survival more frequently. For phase III trials, similarly, trials with targeted and/or hormone therapy used progression-free survival more frequently.


Our study assessed endpoint selection in phase II and phase III clinical trials of advanced breast cancer, which was selected as one example of cancer as it affects millions of females around the world. For phase II trials, a decreasing trend for ORR and an increasing one for PFS was observed. Despite ongoing debate over the use of PFS as an endpoint in advanced breast cancer, it was also the most commonly used primary endpoint in phase III trials. To our knowledge, this is the first study to assess endpoint selection in advanced breast cancer clinical trials over a decade of time and as selection of appropriate endpoints is crucial for the success of clinical trials, changing trends should be considered when deciding upon primary and secondary outcomes measures to demonstrate drug efficacy and safety.