Abstract A30: Intravenous infusion of aGalCer loaded CD14-positive monocytes efficiently promotes amplification of circulating NKT-like cells, resulting immune responses and anti-tumor effects in malignant tumor patients
Authors: Ito Yoshinori 
Published: December 2022

Natural Killer T (NKT) cells are unique lymphocyte lineage that present both NK and T cell phenotype. NKT cells hold strong direct cytotoxic ability toward tumor cells through glycolipid/CD1d complex on tumor cells and NKG2D pathway. NKT cells secrete large amounts of IFNg and stimulate CD8 and NK cells as indirect cytotoxic effects. To elicit NKT cells responses in cancer patients, adoptive transfer of a-galactosyl ceramide (aGalCer) loaded APCs was exploited in a decade. iNKT cancer therapy developed by Taniguchi M, et al. is an immunotherapy using aGalCer loaded CD14-positive monocytes (CD14-Mo) infusion. This culture method is quite unique and convenient. It requires only 2 days culture. We completed the treatment of 14 malignant tumor patients with aGalCer loaded CD14-Mo (aGalCer CD14-Mo) and evaluated immune responses and anti-tumor effects. Methods: Autologous mononuclear cells were isolated by leukapheresis and then separated by Ficoll-Hypaque centrifugation. Monocytes were purified by CD14 positive selection. CD14-Mo was cultured for 2 days with GM-CSF and aGalCer. After cultivation, all cells were frozen and stored in liquid nitrogen until use. Usually above 95% of aGalCer CD14-Mo is expressing CD40. For tumor treatment, patients were injected at least twice with aGalCer CD14-Mo intravenously (IV) (0.5-2.0 x 108 cells per injection) with 3-4 weeks interval. One of the patients was injected with aGalCer CD14-Mo subcutaneously (SC). We evaluated safety and efficacy of iNKT cancer therapy by CTCAE, tumor maker, RECIST and immunological analysis. Fourteen patients, including NSCLC (3 cases), renal cancer (2 cases), ovarian cancer (2 cases), DLBCL (2 cases), urothelial (2 cases), cervical, colorectal and H&N cancer, were enrolled in this immunotherapy between 2020-2021. Results: In all cases, we could not observe any therapy-related adverse effects above CTCAE Grade 2. Several anti-tumor effects such as tumor marker reduction and/or SD were observed in 54.5% of evaluated cases and also increased numbers of CD8 cells and/or NK cells were observed in 83.3% of evaluated cases. Number of CD3+CD56+ positive cells in peripheral blood usually called as circulating NKT-like cells (cNKT) was amplified in 81.8% of patients whom injected aGalCer CD14-Mo IV. Among patients with amplified cNKT, CD8/NK upregulation and anti-tumor effects were observed in 100% and 75% of patients respectively after aGalCer CD14-Mo IV infusion. In the patients treated by aGalCer CD14-Mo IV with 5-FU/CDDP infusion or regular radiotherapy and the patient treated by aGalCer CD14-Mo SC infusion, any of cNKT amplification was not observed. Conclusion: aGalCer CD14-Mo IV infusion (iNKT cancer therapy) efficiently promote cNKT amplification. cNKT amplification clearly related with immune responses and anti-tumor effects. cNKT amplification seems to be abolished by combination therapy such as regular radiotherapy or chemotherapy. However, it is required more accumulation of cases to confirm. cNKT status is quite useful for the evaluation of iNKT cancer therapy.

Citation Format: Yoshinori Ito. Intravenous infusion of aGalCer loaded CD14-positive monocytes efficiently promotes amplification of circulating NKT-like cells, resulting immune responses and anti-tumor effects in malignant tumor patients [abstract]. In: Proceedings of the AACR Special Conference: Tumor Immunology and Immunotherapy; 2022 Oct 21-24; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(12 Suppl):Abstract nr A30.