Eighteen patients with refractory and progressive solid tumors were treated with a single round of triple modified oncolytic adenovirus (Ad5/3-Cox2L-D24). Ad5/3-Cox2L-D24 is the first non-Coxsackie-adenovirus receptor-binding oncolytic adenovirus used in humans. Grades 1-2 flu-like symptoms, fever, and fatigue were seen in most patients, whereas transaminitis or thrombocytopenia were seen in some. Non-hematological grades 3-5 side effects were seen in one patient with grade 3 ileus. Treatment resulted in high neutralizing antibody titers within 3 weeks. Virus appeared in serum 2-4 days after treatment in 83% of patients and persisted for up to 5 weeks. One out of five radiologically evaluable patients had partial response (PR), one had minor response (MR), and three had progressive disease (PD). Two patients scored as PD had a decrease in tumor density. Tumor reductions not measurable with Response Evaluation Criteria In Solid Tumors (RECIST) were seen in a further four patients. PR, MR, stable disease, and PD were seen in 12, 23.5, 35, and 29.5% of tumor markers analyzed, respectively (N=17). Ad5/3-Cox2L-D24 appears safe for treatment of cancer in humans and extended virus circulation results from a single treatment. Objective evidence of anti-tumor activity was seen in 11/18 (61%) of patients. Clinical trials are needed to extend these findings.