Learning from every patient: Real-world clinical outcomes of patients with metastatic triple-negative breast cancer treated in the community oncology setting.

e12554 Background: Triple-negative breast cancer is a biologically aggressive disease that accounts for 15% of all breast cancers, of which around 4-5% are metastatic (mTNBC) at diagnosis. Notably, there is no standard of care for mTNBC in the first line (1L) setting. This, in addition to higher relapse rates and poor long-term survival, warrants evaluation of real-world treatment patterns, especially in the 1L setting, to better inform on clinical outcomes. Methods: This observational, retrospective, chart review study included a cohort of twenty-six mTNBC patients from six different sites Australia, who commenced 1L treatment between July 1, 2012 and June 30, 2015. Medical records of eligible patients were abstracted using electronic case report forms after gaining relevant ethics approvals. Data on treatment patterns and clinical outcomes in the 1L setting were then collected from the index date until the end of data abstraction or death. The index date is defined as the date of initiation of 1L systemic therapy for mTNBC. Results: In the 1L setting, patients that received combination (52%) chemotherapy was slightly higher than single-agent (48%) chemotherapy. The commonest combination used was Carboplatin-Gemcitabine (12%), and the most common monotherapy was Nab-Paclitaxel (24%). The overall response rate and disease control rate were estimated to be 32% and 60% in the 1L setting. The median duration of treatment and the median time to next line of therapy were calculated to be 98 days and 12.45 (95% CI 2.79, 20.30) months respectively. Importantly, the median progression free survival (sensitivity analysis) and the median overall survival were estimated to be 3.17 (95% CI 1.91, 5.09) and 10.41 (95% CI 5.36, 16.53) months respectively. Conclusions: Chemotherapy is currently the mainstay of treatment for mTNBC. However, disease progression and chemo-related toxicities warrant stratified use of more efficacious and tolerable treatment options, especially in the 1L setting. Results from this study could be useful in comparing the efficacy and cost effectiveness of these emerging targeted and immuno-therapies outside the clinical trial setting.