Anti-Vα24Jα18 TCR Antibody Tunes iNKT Cell Responses to Target and Kill CD1d-negative Tumors in an FcγRII (CD32)-dependent Manner.

Invariant natural killer T (iNKT) cells play an essential role in antitumor immunity by exerting cytotoxicity and producing massive amounts of cytokines. iNKT cells express invariant T-cell receptors (TCR) to recognize their cognate glycolipid antigens such as α-galactosylceramide (α-GalCer) presented on CD1d. We recently reported that iNKT cells recognize CD1d-negative leukemia cell line K562 in a TCR-dependent manner. However, it remains controversial how iNKT cells use TCRs to recognize and exhibit cytotoxic activity toward CD1d-negative tumors cells without CD1d restriction. Here, we report that iNKT cells exerted cytotoxicity toward K562 cells via a carried over anti-Vα24 TCR mAb from positive selection by magnetic bead sorting. We found that addition of the anti-Vα24Jα18 TCR mAb (6B11 mAb) rendered iNKT cells cytotoxic to K562 cells in an FcγRII (CD32)-dependent manner. Moreover, iNKT cells treated with 6B11 mAb became cytotoxic to other CD32+ cell lines (U937 and Daudi). In addition, iNKT cells treated with 6B11 mAb suppressed K562 cell growth in a murine xenograft model in vivo. These data suggest that anti-iNKT TCR mAb treatment of iNKT cells can be applied as a therapeutic strategy to treat CD32+ cancers such as leukemia, lymphoma, and lung cancer. SIGNIFICANCE: Our findings unveiled that iNKT cells recognize and kill CD1d-negative target tumors via the anti-iNKT TCR mAb bound to CD32 at the tumor site, thereby bridging iNKT cells and CD1d-negative tumors. These findings shed light on the therapeutic potential of anti-iNKT TCR mAbs in NKT cell-based immunotherapy to treat CD1d-negative CD32+ cancers.

Long-term treatment outcomes in gastric cancer with oligometastasis.

Aim: While surgery is essential for curative treatment of gastric cancer with oligometastasis, its target, timing, and possibility of combination with other treatments are unclear. We herein investigated the clinical course and long-term outcomes of gastric cancer with oligometastasis in the real world setting to determine the optimal therapeutic strategy. Methods: The present study retrospectively analyzed 992 patients who received any treatment for metastatic or recurrent gastric adenocarcinoma at Tokyo Metropolitan Komagome Hospital between 2007 and 2019. Oligometastasis was defined as any one of the following: liver metastases (HEP) <3; lung metastases (PUL) <3; unilateral adrenal gland metastasis (ADR); para-aortic lymph node metastasis (PALN); or one, distant, lymph node metastasis, excluding the regional lymph nodes (LYM). Overall survival was compared by the characteristics and treatments for the oligometastasis, and univariate and multivariate analyses were used to identify the prognostic factors of overall survival. Results: Ninety-seven patients (9.8%) with the following metastasis sites were enrolled: HEP (n = 27), PUL (n = 2), ADR (n = 3), PALN (n = 55), and LYM (n = 10). The median survival time of the cohort was 22.8 months, and the five-year overall survival rate was 28.4%. On multivariate analysis, chemotherapy for the initial treatment (hazard ratio [HR]: 0.438; p = 0.048), distal gastrectomy and/or metastasectomy (HR: 0.290; p = 0.001), and R0 resection (HR: 0.373; p = 0.005) were identified as independent, positive factors of overall survival. Conclusion: The long-term outcomes of gastric cancer in patients with oligometastasis may improve if treatment is begun with chemotherapy rather than surgery.