Abstract
Purpose: NKG2D ligands (NKG2DL) are expressed on various tumor types and immunosuppressive cells within tumor microenvironments, providing suitable targets for cancer therapy. Various immune cells express NKG2D receptors, including natural killer (NK) cells and CD8+ T cells. Interactions between NKG2DL and NKG2D receptors are essential for NK-cell elimination of osteosarcoma tumor-initiating cells. In this report, we used NKG2D-NKG2DL interactions to optimize an immunotherapeutic strategy against osteosarcoma. We evaluated in vitro and in vivo the safety and cytotoxic capacity against osteosarcoma cells of CD45RA- memory T cells expressing an NKG2D-4-1BB-CD3z chimeric antigen receptor (CAR).Experimental Design: CD45RA- cells from healthy donors were transduced with NKG2D CARs containing 4-1BB and CD3z signaling domains. NKG2D CAR expression was analyzed by flow cytometry. In vitro cytotoxicity of NKG2D-CAR+ CD45RA- T cells against osteosarcoma was evaluated by performing conventional 4-hour europium-TDA release assays. For the in vivo orthotopic model, 531MII YFP-luc osteosarcoma cells were used as targets in NOD-scid IL2Rgnull mice.Results: Lentiviral transduction of NKG2D-4-1BB-CD3z markedly increased NKG2D surface expression in CD45RA- cells. Genetic stability was preserved in transduced cells. In vitro, NKG2D-CAR+ memory T cells showed significantly increased cytolytic activity than untransduced cells against osteosarcoma cell lines, while preserving the integrity of healthy cells. NKG2D-CAR+ memory T cells had considerable antitumor activity in a mouse model of osteosarcoma, whereas untransduced T cells were ineffective.Conclusions: Our results demonstrate NKG2D-4-1BB-CD3z CAR-redirected memory T cells target NKG2DL-expressing osteosarcoma cells in vivo and in vitro and could be a promising immunotherapeutic approach for patients with osteosarcoma. Clin Cancer Res; 23(19); 5824-35. ©2017 AACR.
Highlights
Osteosarcoma is the most frequently observed malignant primary bone tumor, typically affecting children and adolescents [1]
We found that NKG2D chimeric antigen receptor (CAR)-redirected CD45RAÀ cells lysed osteosarcoma cells in vitro, and they reduced tumor burden and prolonged survival in mouse models of metastatic osteosarcoma
Osteosarcoma cells express NKG2D ligands (NKG2DL) Cell surface expression of ligands for the NKG2D receptor on the 531MII, U-2 OS, and MG-63 osteosarcoma cell lines was assessed by flow cytometry
Summary
Osteosarcoma is the most frequently observed malignant primary bone tumor, typically affecting children and adolescents [1]. The long-term survival rate for the nonmetastatic type varies from 65% to 70%. Note: Supplementary data for this article are available at Clinical Cancer Research Online (http://clincancerres.aacrjournals.org/). Vant chemotherapy are inefficient for the metastatic type, in which the 5-year survival rate is less than 20% [2]. The rapid development of metastatic lesions and resistance to chemotherapy are the major causes of treatment failure and poor survival rates. Over the past few decades, efforts have been made to intensify dosing, vary timing, and to use multicombinational chemotherapy; no substantial improvement in survival has been achieved. Several adverse effects accompany high-dose chemotherapy [3]. The development of alternative novel therapies is essential
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
