Metastatic Non-Clear Cell Renal Cell Carcinoma (Nccrcc) Treated With Targeted Therapy Agents: Applying The International Metastatic Renal Cell Carcinoma Database Consortium (Imdc) Prognostic Model To Predict Outcomes

396 Background: The International mRCC Database Consortium (IMDC) Prognostic Model (Heng, et al. model, JCO, 2009) was defined and validated in a patient cohort that was comprised of RCC of all histological-subtypes. Clear-cell RCC (ccRCC) accounts for ~80% of RCC cases, and thus it is unknown if this model is reliable in patients with non-ccRCC (nccRCC). Therefore, we sought to evaluate the reliability of the model separately in ccRCC and nccRCC.Data on 2,215 (1,963 ccRCC/252 n-ccRCC) patients treated with 1-st line VEGF-and mTOR targeted therapies were collected from the IMDC. nccRCC included papillary, chromophobe, and other histologies. Patients were assigned to favorable, intermediate, and poor prognosis groups according to the ICDM prognostic model. The discrimination ability for overall survival (OS) was evaluated by C-index.The median OS of the entire cohort was 20.9 months. nccRCC patients were of younger age (p < 0.0001), more often presented with low Hb (p = 0.014) and elevated neutrophils (p = 0.0001), but displayed otherwise similar clinicopathological features compared to ccRCC. OS (22.3 vs. 12.8 months; p < 0.0001), and TTF (7.8 vs. 4.2 months; p < 0.0001) were worse in nccRCC compared to ccRCC. The hazard ratio for death (OS) and treatment failure (TTF) when adjusted for the prognostic factors was 1.41 (95%CI 1.19, 1.67, p < 0.0001) and 1.54 (95% CI 1.33, 1.79, p < 0.0001), respectively. The IMDC prognostic model reliably discriminated three risk groups to predict OS and TTF in nccRCC; the median OS and TTF of favorable, intermediate, and poor prognosis groups were 31.4, 16.1, and 5.1 months (p < 0.0001) and 9.6, 4.9, and 2.1 months (p < 0.0001), respectively. The C-indices for OS were 0.66 and 0.64 for the IDCM and MSKCC criteria, respectively.Patients with nccRCC treated with targeted therapies have a significantly worse outcome than ccRCC patients. The IMDC prognostic model reliably predicts OS and TTF in nccRCC and ccRCC.