Platinum Retreatment In Second Line Chemotherapy For Metastatic Urothelial Carcinoma (Uc): Assessing The Concept Of Platinum Sensitivity And Predictors Of Survival.

e16024 Background: Although there is no uniform consensus about standard second-line chemotherapy for patients with metastatic UC, retreatment with second line platinum-based regimens (SLPR) is commonly practiced. This study aimed to identify factors predicting survival in SLPR including the concept of platinum sensitivity. Methods: Pooled data of patients at three institutions with metastatic UC treated with SLPR for disease progression following standard first-line platinum regimens was assessed. The influence of potential prognostic factors on overall survival (OS) including the platinum-free interval (PFI) (defined as the interval from completion of the first-line to initiation of second-line platinum-based therapy), were assessed through univariate and multivariate Cox-regression analysis. Results: A total of 51 patients were eligible for analysis. SLPR differed from first-line in 45 patients (88%): nedaplatin (25 patients); carboplatin (11 patients); oxaliplatin (10 patients); and cisplatin (5 patients). Eighteen patients (35%) had objective response to first-line platinum regimens, whereas 16 (31%) had objective response to second-line (1 CR (2%); 15 PR (29%); 13 SD (25%); 17 PD (33%); Unknown (12%)). The median progression free survival (PFS) and OS from second-line treatment were 5.0 and 10.3 months respectively. The PFI did not predict PFS (median PFS, 4.2 and 5.3 months for interval < and ≥ 6 months respectively, p= 0.65) or OS (median OS, 10.3 and 9.8 months for interval < and ≥ 6 months respectively, p = 0.73). In multivariate analysis, liver metastasis (HR 4.17, 95% CI: 1.67-10.31, p = 0.004) and ECOG PS ≥ 1 (HR: 2.19, 95% CI: 1.04 – 4.61, p = 0.04) were the only independent factors for inferior OS. Conclusions: Although 31% of patients had objective response with platinum retreatment, the PFI was not predictive of survival in UC. Liver metastasis and ECOG PS were predictors of inferior survival in this patient population. Further studies are required to identify those who may benefit from SLPR.