Preclinical ReportsPre-activation with TLR7 in combination with thioridazine and loratadine promotes tumoricidal T-cell activity in colorectal cancerLin, Xiaotana,,b,,*; Zhang, Junfanga,,*; Wang, Xiaomeia; Lin, Guimiaoa; Chen, TingtingaAuthor Information aDepartment of Physiology, School of Basic Medical Sciences, Shenzhen University Health Sciences Center bDepartment of Family Planning, Second Clinical Medical College of Jinan University, Shenzhen People’s Hospital, Shenzhen, China *Xiaotan Lin and Junfang Zhang contributed equally to the writing of this article. Received 12 February 2020 Revised form accepted 16 June 2020 Correspondence to Tingting Chen, Shenzhen University, Shenzhen, China, E-mail: [email protected] Anti-Cancer Drugs: November 2020 - Volume 31 - Issue 10 - p 989-996 doi: 10.1097/CAD.0000000000000972 Buy Metrics Abstract Colorectal cancer (CRC) is the third most common malignancy worldwide. Our previous studies have shown that combinatorial treatment with thioridazine and loratadine may effectively inhibit CRC. However, the translation of these research findings to clinical practice was impaired by issues related to a lack of therapeutic specificity and to immune evasion. Toll-like receptor (TLR) agonists have been used as adjuvants to enhance the effectiveness of cancer vaccines. The aim of this study was to evaluate the therapeutic efficiency of immunotherapy with thioridazine and loratadine in combination with resiqumiod (R848), a small-molecule TLR7 agonist, in suppressing CRC growth in a mouse model. Twenty-four BALB/c mice were randomly assigned to treatment with PBS, R848, thioridazine + loratadine, or thioridazine + loratadine + R848. Cytokine levels were measured with ELISA. Overall survival, as well as tumor volume and tumor weight, was recorded. Cytotoxicity was measured by counting the numbers of CD8 and CD3-positive (CD8+CD3+) or CD4 and CD3-positive (CD3+CD4+) T-cells. The immune response induced by cytokines (as interferon-γ, interleukin-6, and tumor necrosis factor-α) was significantly stronger in mice treated with thioridazine + loratadine + R848. Moreover, thioridazine + loratadine + R848 significantly delayed tumor development and prolonged survival, which was associated with enhanced immune response and dendritic cell maturation. This study suggested that thioridazine + loratadine + R848 combinatorial treatment may be effective in overcoming immune evasion by tumor cells, with promising therapeutic potential in CRC. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.