Individualizing renal cell carcinoma treatment through biomarkers discovery in the era of immune checkpoint inhibitors: where do we stand?

PURPOSE OF REVIEW: The treatment landscape of metastatic renal cell carcinoma has greatly evolved over the past fifteen years, leading to a significant improvement in the outcome of our patients. However, there is still an urgent need for predictive biomarkers that could guide our treatment selection, especially in the present era of immune-based treatments. RECENT FINDINGS: A number of putative biomarkers of immunotherapy activity have been proposed over the past few years, including PD-L1 immunohistochemical expression, tumor mutational burden, neoantigens load, insertions and deletions, complex gene signatures, as well as lymphocytic subpopulations (either circulating or tumor-infiltrating). However, despite preliminary intriguing findings, no biomarker for immune checkpoint activity has emerged so far, that could be used in everyday clinical practice, mainly due to preliminary, or frankly, conflicting results. SUMMARY: The quest for an 'ideal' biomarker, which should be characterized by adequate specificity, sensibility, predictive (and not just prognostic) value, robustness, reproducibility, ease of evaluation and low cost, is still ongoing.