Clinical outcomes of metastatic non-clear cell renal cell carcinoma: a real-world single-centre experience

In the current study, we aimed to characterize the clinicopathological features of metastatic non-clear cell renal cell carcinoma (nccRCC) using retrospective data from our centre and to assess the clinical outcomes of patients treated with first-line immunotherapy-tyrosine kinase inhibitor (IO-TKI) therapy versus TKI monotherapy.

We conducted retrospective analysis of 105 metastatic nccRCC patients at our centre from Jan 2006 to Oct 2022. The end points included progression-free survival (PFS) and overall survival (OS). Survival analysis was performed using the Kaplan-Meier curve and multivariate Cox regression model.

Among metastatic nccRCC patients, the most prevalent histology was papillary RCC (39.0%). The most common distant metastasis site was lung metastasis (52.4%), followed by bone metastasis (33.3%). The proportion of the favourable, intermediate and poor IMDC risk group were 19.0%, 54.3% and 26.7%, respectively. Among metastatic nccRCC patients, 26 received first-line IO-TKI therapy and 79 received first-line TKI monotherapy therapy. During the median follow-up of 22.2 months, the 1-year PFS and 3-year OS of IO-TKI group was 46.2% and 48.0%, respectively. In comparison, the 1-year PFS and 3-year OS of TKI monotherapy group was 34.9% and 33.7%, respectively. According to the Cox regression model, unclassified RCC pathology (HR = 2.027, p = 0.023) and poor IMDC risk group (HR = 2.285, p = 0.011) were identified as the independent risk factors for PFS. Poor IMDC risk group (HR = 2.638, p = 0.007) was also identified as the independent risk factors for OS.

For metastatic nccRCC, unclassified RCC pathology and poor IMDC risk group were identified as independent risk factors for poor prognosis and IO-TKI showed promising efficacy in patients with metastatic nccRCC.