Adaptive NK Cell Therapy Modulated by Anti-PD-1 Antibody in Gastric Cancer Model.

Shahrokh Abdolahi,Kaveh Baghaei,Javad Verdi,Mohammad Ahmadvand,Hamid Asadzadeh Aghdaei,Samad Muhammadnejad,Zeinab Ghazvinian,Mohammad Reza Zali,Somayeh Ebrahimi-Barough,Jafar Ai

doi:10.3389/fphar.2021.733075

Abstract

Recently, adaptive NK cell therapy has become a promising treatment but has limited efficacy as a monotherapy. The identification of immune checkpoint inhibitor (ICI) molecules has opened a new horizon of immunotherapy. Herein, we aimed to demonstrate the cytotoxic effects of a polytherapy consisting of ex vivo expanded IL-2-activated NK cells combined with human anti-PD-1 antibody as an important checkpoint molecule in a xenograft gastric cancer mouse model. EBV-LCL cell is used as a feeder to promote NK cell proliferation with a purity of 93.4%. Mice (NOG, female, 6–8 weeks old) with xenograft gastric tumors were treated with PBS, ex vivo IL-2-activated NK cells, IL-2-activated NK cell along with human anti-PD-1 (Nivolumab), and IL-2-activated pretreated NK cells with anti-PD-1 antibody. The cytotoxicity of ex vivo expanded NK cells against MKN-45 cells was assessed by a lactate dehydrogenase (LDH) assay. Tumor volume was evaluated for morphometric properties, and tumor-infiltrating NK cells were assessed by immunohistochemistry (IHC) and quantified by flow cytometry. Pathologic responses were considered by H and E staining. Ex vivo LDH evaluation showed the cytotoxic potential of treated NK cells against gastric cancer cell line. We indicated that the adoptive transfer of ex vivo IL-2-activated NK cells combined with anti-PD-1 resulted in tumor growth inhibition in a xenograft gastric cancer model. Mitotic count was significantly decreased (*p < 0.05), and the tumor was associated with improved infiltration of NK cells in the NK-anti-PD-1 pretreated group (*p < 0.05). In conclusion, the combination approach of activated NK cells and anti-PD-1 therapy results in tumor growth inhibition, accompanied by tumor immune cell infiltration in the gastric tumor model.

Highlights

Gastric cancer (GC) is the fifth leading cause of cancer and the third leading cause of death. (Thrift and El-Serag 2020)
Quantification of mean fluorescence intensity (MFI) showed that anti-PD-1 treatment improved CD69 expression (p < 0.002), but no significant changes were observed in NKG2D marker after treatment with IL-2stimulated Natural killer (NK) cells with anti-PD-1 (Figures 2C,D,E)
In order to explore the effect of adaptive NK cell therapy combined with Nivolumab in tumor growth in vivo, we further investigated the impact of interventions on the morphometric properties in the subcutaneous transplantation mouse model of gastric cancer using MKN-45 cell line

Summary

Introduction

Gastric cancer (GC) is the fifth leading cause of cancer and the third leading cause of death. (Thrift and El-Serag 2020). GC has low clinical symptoms, and it usually progresses at the time of diagnosis, making it challenging to treat patients. Various treatments can be considered, including surgery, chemotherapy, radiation therapy, and targeted therapies (Meza-Junco, Au et al, 2011; Wadhwa, Taketa et al, 2013). Even after conventional treatments, many patients experience a recurrence of the disease and eventually, cancer metastasizes to other tissues (Enzinger and Mayer 2003). Consideration of innovative therapeutic approaches is of great importance. There is an increasing investigation in establishing an effective immune cell-based therapy for GC by ex vivo activating and expanding immune cells. Multifarious studies have presented the therapeutic potential of effective immunotherapy of immune cells (Rezvani, Daher et al, 2020; Ingram, Madan et al, 2021)

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