AbstractImmunotherapy has obtained substantial impact on the clinical treatment of melanoma which is largely resistant to current therapies as chemotherapy and radiotherapy. Oncolytic virotherapy of melanoma is an appealing approach for inducing not only tumor cell death but also antitumor immunity. Furthermore, NK cells, a lineage of innate lymphocytes, not relying on peptides presented in an HLA class I context, have gained more and more attention as anti-melanoma effector cells. However, the combination of oncolytic adenovirus and NK cells has not yet been explored in melanoma. In this study, the combinational efficacies of oncolytic virus H101 and NK cells was tested in vitro. The combination of H101 and NK cells resulted more efficient killing of tumor cells (HT29, A549 and HepG2) compared to the monotherapies, and displayed no significant cytolytic effect of normal cells (HUVEC and MRC-5). In addition, we present a patient with right maxillary sinus malignant melanoma who was treated with the combination of H101 and adoptive NK cells. We observed intratumoral injections of H101 without dose-limiting toxicity. H101 injections stimulated self-immunity response with transient whole body fever. Furthermore, NK injections caused tumor temperature rise although contralateral cheek temperature was normal and body temperature was normal. Data are consistent with the hypothesis that virus-infected cancer cells attracted NK accumulation within tumor. The homing NK cells attacked targeted cancer cells, causing local temperature rise. Two courses of combination therapy in conjunction mediated the significant durable regression of melanoma, which had been ongoing for >22 months, and it represents a new immunotherapy approach for the treatment of these patients.Citation Format: Lin Chen, Xianju Chen, Xiankui Tan, Meng Li, Fang Hu, Haiyan Zhang, Xiaoyuan Wang. A combinational therapy of oncolytic virus and nature killer cells for melanoma treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4072.