Assessment for markers of poor prognosis in a real-world evidence study of treatment patterns in patients with HR+/HER2- locally advanced or metastatic breast cancer in Korea and Taiwan.

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e13083 Background: To assess how patient characteristics impact treatment patterns and real-world effectiveness among patients with hormone receptor (HR+)/human epidermal growth receptor 2-negative (HER2-) locally advanced and metastatic breast cancer (ABC) in Korea and Taiwan. Methods: We conducted a retrospective chart review comprising 227 female patients aged ≥ 18 years and diagnosed HR+/HER2- ABC in Korea and Taiwan between 2015-2017. Those having at least one of the following characteristics, shown previously to negatively impact prognosis, formed the poor prognostic cohort (PPC): ECOG PS > 0, not bone-only disease, liver metastases, or negative PgR status. Anonymized data on patient characteristics, treatment pathways, progression-free survival, and grade 3 or higher adverse events (AEs) of interest was abstracted. Descriptive statistics and Kaplan Meier methods were used to assess the outcomes. Results: The mean (range) age was 57.1 (29 - 83) years. A total of 193 (85.0%) patients were PPC. Endocrine regimens were the most frequent first-line therapies used by 50.3% and 67.6% of patients in the PPC and non-PPC cohorts, respectively. Chemotherapy regimens were used by 25.9% and 17.6% as initial systemic therapy and by 60.1% and 35.3% at any time following diagnosis of ABC, for PPC and non-PPC, respectively. The median progression-free survival time, based on first-line therapy, was 8.3 (95%CI: 6.9 – 10.4) months for PPC versus 11.5 (95%CI: 5.5 – 12.0) months in non-PPC. The proportion of patients with at least 1 grade 3 or higher AEs of interest during first-line therapy was higher in the PPC cohort compared to the non-PPC cohort, 54.4% vs. 44.1% respectively. The most common AEs reported were leukopenia, asthenia/fatigue and neutropenia occurring in 27.5%, 28.0% and 20.7% of the PPC cohort and 23.5%, 2.9%, and 14.7% of the non-PPC cohort, respectively. Conclusions: The existence of one or more poor prognostic factors is associated with a higher chemotherapy use any time following diagnosis of ABC, as well as lower median progression-free survival and a higher likelihood of having an adverse event during first line therapy, compared to non-PPC cohort. These results suggest that patient poor prognostic characteristics can be drivers for therapy selection.