Application of the Meet-URO score to metastatic renal cell carcinoma patients treated with second- and third-line cabozantinib

Background: The addition of neutrophil-to-lymphocyte ratio (NLR) and bone metastases to the International Metastatic RCC Database Consortium (IMDC) score (by the Meet-URO score) has been shown to better stratify pretreated metastatic renal cell carcinoma (mRCC) patients receiving nivolumab. This study aimed to validate the Meet-URO score in patients receiving cabozantinib to assess its predictivity and prognostic role. Methods: A multicenter retrospective analysis evaluated mRCC patients receiving -secondline cabozantinib. NLR, IMDC score and bone metastases were assessed before the start of cabozantinib. The primary endpoint was overall survival (OS). Harrell's c-index was calculated to compare the accuracy of the prediction of the two scores. Results: Overall, 174 mRCC patients received cabozantinib as second and third line (51.7% and 48.3%, respectively) with a median follow-up of 6.8 months. A shorter median overall survival (mOS) was observed for the IMDC poor-risk group, NLR >= 3.2 and the presence of bone metastases, while the IMDC intermediate-risk group had a similar mOS to the favourable-risk one. Applying the Meet-URO score, three risk groups were identified: group 1 (55.2% of patients) with a score of 0-3, group 2 (38.5%) with a score of 4-8 and group 3 (6.3%) with a score of 9. Compared to group 1 (mOS: 39.4 months), a statistically significant worse mOS was observed in group 2 (11.2 months) and group 3 (3.2 months) patients, respectively. The Meet-URO c-index score was 0.640, showing a higher discriminative ability than the IMDC score (c-index: 0.568). Conclusion: This analysis showed that the Meet-URO score provides a more accurate prognostic stratification than the IMDC score in mRCC patients treated with >= second-line cabozantinib besides nivolumab. Moreover, it is an easy-to-use tool with no additional costs for clinical practice (web-calculator is available at: https://proviso.shinyapps.io/Meet-UR015_ score/). Future investigations will include the application of the Meet-URO score to the first-line immunotherapy-based combination therapies.