Retrospective Comparison of Triple-sequence Therapies in Metastatic Renal Cell Carcinoma

BackgroundThe optimal sequence of targeted therapy in patients with metastatic renal cell carcinoma (mRCC) has not been defined.ObjectiveTo describe the efficacy and toxicity of the most common sequences of targeted therapy, namely, receptor tyrosine kinase inhibitor (rTKI) and mammalian target of rapamycin inhibitor (mTORi), in different sequences after failure of vascular endothelial growth factor signaling inhibition (VEGFi) in first-line therapy.Design, setting and participantsRetrospective study of 103 patients receiving VEGFi-rTKI-mTORi (n = 62) or VEGFi-mTORi-rTKI (n = 41) at two German academic centers.InterventionSequence of systemic targeted treatment.Outcome measurements and statistical analysisResponse was assessed using Response Evaluation Criteria in Solid Tumors 1.0 and toxicity was measured using the Common Terminology Criteria for Adverse Events 3.0. Progression-free survival (PFS) and overall survival (OS) were estimated by the Kaplan-Meier method. Predictors of survival were analyzed using Cox regression.Results and limitationsSequence groups did not significantly differ by patient characteristics and response rate following first VEGFi failure. Median PFS for second-line therapy was 4.6 mo (95% confidence interval [CI], 3.8–5.4), 4.1 mo (95% CI, 3.4–4.9) for rTKI treatment, and 5.4 mo (95% CI, 2.7–8.1) for mTORi treatment (p = 0.400). No differences in PFS were observed among third-line therapy groups (3.6 mo for mTORi; 3.7 mo for rTKI). Treatment duration following first VEGFi failure (combined second- and third-line PFS) was 10.0 mo for VEGFi-rTKI-mTORi and 12.2 mo for VEGFi-mTORi-rTKI (p = 0.103). No significant differences in OS were observed among sequence groups (33.7 mo [95% CI, 30.4–37.1] for VEGFi-rTKI-mTORi; 38.7 mo [95% CI, 24.4–52.9] for VEGFi-mTORi-rTKI). Primary resistance on first-line therapy was an independent predictor of OS, but type of sequence was not. Limitations are the retrospective design and limited numbers of cases.ConclusionsThe sequence therapies VEGFi-mTORi-rTKI and VEGFi-rTKI-mTORi with the currently available agents appear to be equally efficacious in terms of PFS, OS, and response rate, with no apparent beneficial effect with an early use of mTORi.