Long-term outcomes of tyrosine kinase inhibitor discontinuation in patients with metastatic renal cell carcinoma

Purpose: The purpose of the current study was to evaluate the clinical outcomes of patients with metastatic renal cell carcinoma (mRCC) who interrupted vascular endothelial growth factor receptor tyrosine kinase inhibitor (VEGFR-TKI) therapy. Methods: A retrospective analysis of medical records was performed on all patients with mRCC treated with VEGFR-TKIs between January 2008 and July 2014 (n = 505). Patients who achieved stable disease (SD) or a better response under TKI and later discontinued TKI treatment for any reason with the exception of disease progression were included in the analysis. Results: We identified 32 patients (sunitinib = 20, sorafenib = 7, and pazopanib = 5). The responses to VEGFR-TKIs were complete response (CR, n = 4), partial response (PR, n = 11), SD (n = 15), and controlled but nonmeasurable response (n = 2). Median time to TKI discontinuation from the initiation of VEGFR-TKI therapy was 16.6 months (95 % CI 12.8-20.3), and the main cause of VEGFR-TKI discontinuation was toxicity (n = 19, 59.4 %). At the time of analysis, 16 patients had disease progression and one patient died. With a median follow-up duration of 51.7 months (range 11.5-87.6), median progression-free survival (PFS) after TKI discontinuation was 20.2 months (95 % CI 6.4-34.0). In multivariate analysis, the duration of TKI therapy (<1 year) before TKI discontinuation was an independent significant prognostic factor of poor PFS (p = 0.045). Among 11 patients who were retreated with the same TKI, two patients (18.2 %) achieved PR and nine achieved SD (81.8 %). Conclusions: VEGFR-TKI could be interrupted at least temporarily when clinically warranted in patients with mRCC sufficiently controlled by TKIs.