363P - Maintenance chemotherapy is effective in patients with metastatic triple negative breast cancer after first-line platinum-based chemotherapy

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BackgroundPlatinum-based chemotherapy (PBCT) has gained an important position as a first-line treatment for metastatic triple-negative breast cancer (mTNBC). We assessed whether maintenance chemotherapy is superior to observation after first-line PBCT in patients with mTNB. MethodsA total of 265 patients with mTNBC who exhibited disease control after 4-6 cycles of first-line PBCT at the Fudan University Shanghai Cancer Center from January 2008 to November 2016 were retrospectively analyzed. 107 patients who continued without additional treatment were defined as the control observation group, and the remaining 158 patients who continued to receive maintenance therapy were defined as the maintenance treatment group. ResultsThe median progression-free survival (PFS) time in the maintenance group was 9.63 months, which was significantly longer than the PFS time of 7.47 months in the observation group (HR 0.49, 95% CI 0.37-0.67, P<0.0001). The median overall survival (OS) of the observation group and the maintenance group was 25.37 months and 31.27 months, respectively (HR 0.65, 95% CI 0.44-0.95, P=0.019). Multivariate analyses suggested that maintenance chemotherapy is an independent predictive factor for PFS and OS. Interaction and stratified analyses showed no difference in the PFS between the single-drug maintenance group and the two-drug maintenance group. The most common adverse event in this study was hematologic toxicity. Except for hand-foot syndrome (0 vs. 7.6%, P=0.004), the incidence of other adverse events was not significantly different between the observation and maintenance groups. ConclusionsAfter achieving disease control with first-line PBCT in mTNBC patients, single-drug maintenance chemotherapy is recommended. Legal entity responsible for the studyFudan University Shanghai Cancer Center. FundingShanghai Municipal Science and Technology Commission Guidance Project, China (contract no. 18411967800); Shanghai Municipal Commission of Health and Family Planning (grant no. 201640069); Shanghai Natural Science Foundation (grant no. 17ZR1405700); and research grant from Shanghai Hospital Development Center (grant no. SHDC12018X03). DisclosureAll authors have declared no conflicts of interest.