This is a phase I/II, national multi-center study of different doses and schedules of low-dose oral cyclophosphamide in combination with fixed dose everolimus in patients with mRCC not amenable to or progressive after a VEGF-receptor tyrosine kinase inhibitor containing treatment regimen. Phase I part: Patients will be enrolled in cohorts of 5 per dose level. The first 5 patients enrolled will be assigned to dose level 0 in order to assess immune and angiogenic effects caused by everolimus monotherapy. The second 5 patients enrolled will be assigned to dose level 1. If there are ≤1 dose-limiting toxicities (DLTs) experienced by the first 5 patients in a cohort during the first 28 days after the first study treatment, further patients will be entered in the next dose level. Entry of patients into the expansion cohort will not occur until at least 28 days after the last patient in the escalation phase received his/her first study treatment. At the final dose level recommended for the phase II study a minimum of 10 patients will be treated. Phase II part: In the phase 2 part of the study up to 56 patients will be treated at the dose level that has been selected based on its capacity to most selectively deplete circulating Treg levels in the phase 1 part of the study. Based on data of patients with mRCC treated with everolimus monotherapy after previous treatment with sunitinib ± sorafenib, the investigators aim to increase the number of patients who are alive and cancer progression free at 4 months from 50% to 70% by adding metronomic cyclophosphamide. In addition, the investigators consider this increase meaningful as long as the combination treatment does not cause combination treatment related toxicity ≥ grade 3 in ≥ 30% of patients.