The rapalogs everolimus and temsirolimus that inhibit mTOR signaling are used as antiproliferative drugs in several cancers. Here we investigated the influence of rapalogs-mediated immune modulation on their antitumor efficacy. Studies in metastatic renal cell carcinoma patients showed that everolimus promoted high expansion of FoxP3+ Helios Helios+Ki67+ regulatory CD4 T cells (Tregs ). In these patients, rapalogs strongly enhanced the suppressive functions of Tregs , mainly in a contact-dependent manner. Paradoxically, a concurrent activation of spontaneous tumor-specific Th1 immunity also occurred. Furthermore, a high rate of Eomes+ CD8+ T cells was detected in patients after a long-term mTOR inhibition. We found that early changes in the Tregs /antitumor Th1 balance can differentially shape the treatment efficacy. Patients presenting a shift toward decreased Tregs levels and high expansion of antitumor Th1 cells showed better clinical responses. Studies conducted in tumor-bearing mice confirmed the deleterious effect of rapalogs-induced Tregs via a mechanism involving the inhibition of antitumor T-cell immunity. Consequently, the combination of temsirolimus plus CCR4 antagonist, a receptor highly expressed on rapalogs-exposed Tregs , was more effective than monotherapy. Altogether, our results describe for the first time a dual impact of host adaptive antitumor T-cell immunity on the clinical effectiveness of rapalogs and prompt their association with immunotherapies. ©2016 American Association for Cancer Research.