Comparison of tyrosine kinase inhibitors in the treatment of metastatic renal cell carcinoma with rhabdoid and sarcomatoid differentiations

Objective: To investigate the efficacy of tyrosine kinase inhibitors (TKIs) in the treatment of metastatic renal cell carcinoma (mRCC) with rhabdoid (mRCC-R) and sarcomatoid (mRCC-S) differentiations. Materials and Methods: In this single-institutional cohort study, we included patients with RCC with rhabdoid (RCC-R) and sarcomatoid (RCC-S) differentiation, who were treated with TKIs after metastasis at our institute from 2013 to 2021. Patient characteristics, treatments, and clinical outcomes were recorded and analyzed. Results: We identified 111 patients with RCC--R or RCC--S differentiations, of which 23 patients were included in the final analysis. Of the 23 patients, 10 (43.5%) were grouped as mRCC-R and 13 (56.5%) as mRCC-S. At a median follow-up of 40 months, mRCC-R and mRCC-S progressed in 7 of 10 and 12 of 13 patients, respectively. In addition, four and eight patients died in the mRCC--R and mRCC-S groups, respectively. The median progression-free survival (PFS) of the two groups was 19 months (mRCC-R: 95% confidence interval [CI] 4.08-33.92) and 7 months (mRCC-S: 95% CI 2.03-11.96), while the median overall survival (OS) was 32 months and 21 months, respectively. mRCC--S had a worse prognosis than mRCC--R. Based on the univariate Cox regression model, single metastasis or multiple metastasis of tumor, rhabdoid differentiation, and sarcomatoid differentiation were predictors of PFS but not OS. Conclusion: The efficacy of TKIs in the treatment of mRCC--R and mRCC--S may be different.