Changes in peripheral blood immune cells: their prognostic significance in metastatic renal cell carcinoma patients treated with molecular targeted therapy

Recently, novel molecular targeted agents markedly changed the treatment of renal cell carcinoma (RCC), with promising results. However, there is little understanding of how these agents affect immune cell populations in RCC, an immunogenic tumor. Therefore, we investigated the changes in the peripheral blood immune cells in 58 RCC patients during the first 4 weeks of treatment with sorafenib, sunitinib, everolimus, or temsirolimus and evaluated whether these changes were associated with clinical outcomes. The immunological parameters were the proportion of type-1 (Th1) and type-2 (Th2) T cells, regulatory T cells (Treg), mature dendritic cells, and the neutrophil-to-lymphocyte ratio (NLR). The changes in these immune cells varied with the agents and the clinical response, dichotomized by the median progression-free survival (PFS) time (PFS-short or PFS-long). A significant decrease in the Th1/Th2 ratio was seen after sunitinib treatment only in the PFS-short group, suggesting a shift toward Th2 that down-regulates host immunity. The NLRs indicative of the balance between host immunity and cancer-related inflammation were consistently lower in the PFS-long group than in the PFS-short group, suggesting that lower NLR is associated with better clinical response. Only sunitinib decreased NLR remarkably regardless of PFS status, which may favor anti-tumor immunity. When patients were dichotomized by the cutoff values, Th1/Th2 ratio was not associated with PFS in any targeted therapy, while lower pre-treatment NLR was associated with longer PFS in each targeted therapy. In addition, in RCC patients given sequential targeted therapy, those with a lower baseline NLR survived significantly longer compared with the counterparts. Moreover, those whose baseline NLR was sustained low during the initial therapy survived the longest. Our results suggest the diverse changes in host immune cells in RCC patients during targeted therapy. The changes in NLR during the early phase of targeted therapy may be a powerful discriminator of who will benefit from the subsequent treatment.