Clinical Cancer Epigenetics: Promising results for RRx-001 in a Phase I clinical trial. RRx-001, a hypoxia-activated drug, epigenetically modulates DNA methylation, histone deacetylation, and lysine demethylation. The aim of this phase 1 study was to assess the safety, tolerability, and pharmacokinetics of RRx-001. The investigators report in an open-label, dose-escalation, phase 1 study, the toxicity and activity of RRx-001 on 21 patients with various solid tumors. The authors report no dose-limiting toxicities, a patient with partial response, and 14 patients with stable disease. In addition, 4 patients refractory to chemotherapy became responders after treatment with RRx-001 (Tony Reid, University of California at San Diego, San Diego, CA, USA).