ABSTRACT Aim: There is little evidence that CT has any impact on outcome of pts with MSCC. This analysis was aimed to identify predictors for DC at first disease assessment, in MSCC pts receiving first-line CT. Methods: In the development cohort (68 pts from the multicentric and ongoing E-Dis trial [NCT01248299]), we have developed predictors for DC using a logistic regression model. Then, we applied the predictive model to an independent retrospective cohort of 60 consecutive pts from one center (Lille), and assessed Sensitivity (Se), Specificity (Sp), Positive Predictive Value (PPV), Negative Predictive Value (NPV), Accuracy (A), Discriminative slope (DS) and the calibration with the Brier score (BS). Results: In the development cohort, gender (women), ECOG 0-1, BMI ≥ 18.5, no bone metastasis, albumin ≥ 35g/l and hemoglobin ≥ LLN were associated with DC. Using logistic regression we identified the following 3 prognosticators: BMI ≥ 18.5 (OR 4.5; 95% CI: 0.91-22.5), no bone metastasis (OR 4.6; 95% CI: 0.91-23.2), albumin ≥ 35 g/l (OR 3.5; 95% CI: 1-12.1). Based on the presence or absence of these 3 independent prognosticators, we have built a predictive model using a score from 0 to 3. 64/68 pts were assessable. The DC rate was 64% (41/64), 14.3% (2/14), and 78% (39/50), in the overall population, when score = 0-1, and when score = 2-3, respectively. In the validation cohort, 51/60 patients were assessable. The DC rate was 39.2% (20/51), 12.5% (1/8), and 44.2% (19/43) in the overall population, when score = 0-1, and when score = 2-3, respectively. Se, Sp, PPV, NPV, A, and DS were 95%, 22%, 44%, 88%, 51% and 31.5%, respectively. Model calibration was good since the BS was very low (0.203). Our score was also predictive for death within 90 days (data not shown). Conclusions: We have developed and validated a predictive score for DC at first disease assessment, which includes BMI assessment, bone metastasis status, and albumin level for pts with MSCC receiving first-line CT. Disclosure: E. Francois: Participation to boards : Roche, Merck, Sanofi, Novartis, Celgene; A. Adenis: Bayer (advisory board, research funding). All other authors have declared no conflicts of interest.