KHYG-1 Cells With EGFRvIII-specific CAR Induced a Pseudoprogression-like Feature in Subcutaneous Tumours Derived from Glioblastoma-like Cells

Abstract

Background/Aim: We previously established a novel type of epidermal growth factor receptor variant III (EGFRvIII)-specific chimeric antigen receptor (CAR)expressing natural killer (NK) cell line, designated EvCAR-KHYG-1, which inhibited the growth of glioblastoma (GBM) cells in vitro via apoptosis. Materials and Methods: We investigated the cytokine-producing effect of EvCAR-KHYG-1 cells on GBM-like cell lines and their antitumour effect using in vivo xenograft assays. Results: EvCAR-KHYG-1 cells produced interleukin-2, interferon-γ, and tumour necrosis factor-α on EGFRvIII-expressing U87MG cells. In vivo xenograft assays showed that EvCAR-KHYG-1 cells did not reduce the volume of subcutaneous tumours derived from EGFRvIII-expressing U87MG cells but did reduce tumour cell occupancy. Conclusion: EvCAR-KHYG-1 cells led to expression of cellular immunity-related cytokines on EGFRvIII-expressing U87MG in vitro but did not inhibit tumour progression due to the induction of a pseudo progression-like pathological feature. Future studies investigating the effect of different conditions in vivo are required to study the inhibition of tumour progression in GBM.Glioblastoma (GBM) is one of the most common and aggressive types of primary malignant central nervous system (CNS) tumours occurring in adults (1-3). Despite chemotherapy, radiation, with/without surgical resection, few patients survive for more than 5 years (1, 3). Thus, developing an effective therapy to treat GBM is warranted. Immunotherapy is a promising alternative to conventional treatments, with the possible long-term benefit of generating a sustained antitumour response and potentially targeting both localized and infiltrating tumour cells. Natural killer (NK) cells are potent effector cells in cell-based cancer immunotherapy. They respond rapidly to abnormal cells and represent a crucial effector cell population in adoptive immunotherapy (4). In addition, donor-derived NK cells such as NK-92 and KHYG-1 are being developed for clinical applications (5-8).Chimeric antigen receptor (CAR) is an artificially modified fusion protein consisting of an extracellular antigen-recognition domain fused to an intracellular signalling domain (9, 10). CAR redirects the specificity and function of T-lymphocytes and other immune cells. The general premise for the use of CAR cells in cancer immunotherapy is the rapid generation of tumour-targeted Tcells, bypassing the barriers and incremental kinetics of active immunization (11,12). CAR T-cells are effectively used to treat refractory chronic lymphocytic leukaemia and acute lymphoblastic leukaemia (ALL) (13,14). Specifically, CD19-targeting CAR T-cells have been reported to result in complete response rates of 70-90% in ALL patients (15). However, CAR T-cells exhibited poor therapeutic efficacy against solid tumours (16-18). A clinical trial showed that epidermal growth factor receptor variant III (EGFRvIII)targeted CAR T-cells infiltrated GBM but without objective 3231

Ex Vivo Expanded and Activated Natural Killer Cells Prolong the Overall Survival of Mice with Glioblastoma-like Cell-Derived Tumors

“…The in vivo xenograft assay was performed as described previously [ 50 , 51 ]. Briefly, nonobese diabetes (NOD)/severe combined immunodeficiency (SCID)/γcnull (NOG) mice were purchased from the Central Institute for Experimental Animals (Kanagawa, Japan).…”

Engineered NK Cells Against Cancer and Their Potential Applications Beyond

“…Regarding the nature of the assessed CAR constructs, it was shown that 2 nd generation anti-CD19 CAR-NK cells containing CD3ζ and CD28 costimulatory domains outperformed 1 st generation CARs, whereas 2 nd and 3 rd generation CAR constructs did not seem to confer substantial differences in NK cell functionality ( 215 , 217 ). Investigations on the optimal NK cell source were also conducted, where it was suggested that primary NK sources might be a better option than antiCD19 CAR-NK-92 cells ( 218 , 219 ). In a comparison of CAR PB-NK versus CAR UCB-NK expressing the same antiCD19 CAR construct, it was shown that the former was better in eliminating CD19+ target cells in an effector to target ratio of 1:1 ( 46 ).…”

The War Is on: The Immune System against Glioblastoma—How Can NK Cells Drive This Battle?

“…Murakami et al (2018) [ 241 ] evaluated the engineering of the KHYG-1 NK cell line with an EGFRvIII-specific CAR, and observed the induction of a strong and significant inhibition of EGFRvIII-expressing U87MG GBM cell line growth, through the triggering of apoptosis. A further study by the same group was conducted in 2020 [ 248 ], showing the in vitro secretion of RANTES and—when recognition of U87MG EGFRVIII + tumor cells by CAR-NK cells occurred—a significant secretion of TNF-α, IFN-γ, IL-2, and IL-6 cytokines. However, the treatment of immunodeficient mice bearing the specific target cell apparently failed to control tumor progression, and resulted in greater tumor occupancy, in comparison to PBS-treated mice.…”