During cancer immunoediting, loss of major histocompatibility complex class I (MHC-I) in neoplasm contributes to the evasion of tumours from host immune system. Recent studies have demonstrated that most natural killer (NK) cells that are found in advanced cancers are defective, releasing the malignant MHC-I-deficient tumours from NK-cell-dependent immune control. Here, we show that a natural killer T (NKT)-cell-ligand-loaded tumour-antigen expressing antigen-presenting cell (APC)-based vaccine effectively eradicates these advanced tumours. During this process, we find that the co-expression of Tim-3 and PD-1 marks functionally exhausted NK cells in advanced tumours and that MHC-I downregulation in tumours is closely associated with the induction of NK-cell exhaustion in both tumour-bearing mice and cancer patients. Furthermore, the recovery of NK-cell function by IL-21 is critical for the anti-tumour effects of the vaccine against advanced tumours. These results reveal the process involved in the induction of NK-cell dysfunction in advanced cancers and provide a guidance for the development of strategies for cancer immunotherapy.

BVAC-C is a B cell-based and monocyte-based immuno-therapeutic vaccine transfected with a recombinant human papillomavirus (HPV) 16/18 E6/E7 gene and loaded with alpha-galactosyl ceramide, which is a natural killer T cell ligand. This phase I study sought to determine the tolerability and immunogenicity of BVAC-C in platinum-resistant recurrent cervical cancer patients. Patients with HPV 16-positive or 18-positive recurrent or persistent cervical cancer who had received at least one prior platinum-based combination chemotherapy were enrolled. BVAC-C was injected intravenously three times every four weeks, and dose escalation was planned in a three-patient cohort design at doses of 1 × 107, 4 × 107, or 1 × 108 cells/dose. Eleven patients were enrolled, and six (55%) patients had received two or more lines of platinum-based chemotherapy prior to enrollment. Treatment-related adverse events (TRAEs) were observed in 21 cycles. Most TRAEs were mild fever (n = 6.55%) or myalgia (n = 4.36%). No dose-limiting toxicities occurred. The overall response rate was 11% among nine patients evaluable, and the duration of response was 10 months. Five patients (56%) achieved a stable disease for 4.2–11 months as their best overall response. The median progression-free survival in all patients was 6.8 months (95% CI, 3.2 to infinite months), and the overall survival rate at 6 and 12 months was 89% (95% CI, 71 to 100%) and 65% (95% CI, 39 to 100%), respectively. BVAC-C induced the activation of natural killer T cells, natural killer cells, and HPV 16/18 E6/E7-specific T cells upon vaccination in all patients evaluated. BVAC-C was well tolerated and demonstrated a durable anti-tumor activity with an immune response in HPV 16-positive or 18-positive recurrent cervical carcinoma patients. A Phase 2 efficacy trial is currently underway.

4534 Background: BVAC-B is an autologous B cell- and monocyte-based immunotherapeutic vaccine transfected with recombinant HER2/neu gene and loaded with alpha-galactosyl ceramide, a natural killer T cell ligand. It may have activity against HER2/neu positive cancer. Preclinical data in mouse models have shown promising anti-tumor activity by eliciting broad spectrum of immune responses against HER2/neu positive tumor cells. We report here the results of phase 1 study of BVAC-B in HER2 positive advanced gastric cancer. Methods: Metastatic gastric cancer with IHC > 1+ of HER2/neu were eligible for enrollment. Two weeks before treatment, subjects were admitted to hospital for collection of PBMC and plasma by lymphapheresis. The PBMC were sent to Cellid for vaccine manufacturing which took a day. BVAC-B was given intravenously at 0, 4, 8, and 12 weeks. Subjects received low (2.5X 107 cells/dose), medium (5.0X 107 cells/dose) or high dose (1.0X 108 cells/dose). Endpoints included safety, tolerability and MTD for phase 2 trial. Exploratory outcomes included immune responses after BVAC-B administration. Results: As of January 29, 2020, 8 subjects were treated with BVAC-B at doses of 2.5X 107 cells/dose (n=1), 5.0X 107 cells/dose (n=1) and 1.0X 108 cells/dose (n=6). Median line of therapy at which BVAC-B was administered was 4 (range, 2-9). Mean duration treatment was 1.8 (range 1-4) cycles. The most common treatment related adverse events were fever (n=4, 50%). One subject enrolled in medium dose experienced cytokine release syndrome (G2) with high fever (39.3℃) and hypotension 8 hours after first administration, but was manageable with hydration and supportive management. Other adverse events included increase of AST and ALT (G1, n=1 and G2, n=2), and hypotension (G1, n=1). There were no adverse events which led to treatment discontinuation. Immunologic response analysis showed that BVAC-B induced activation of natural killer T cells, natural killer cells, HER2/neu specific T cells, and release of HER2/neu specific antibody upon vaccinations in few patients who were evaluated. Conclusions: BVAC B is feasible and has acceptable toxicity profile. We considered all dose evaluated in this study available for phase 2 study, given that the maximum tolerated dose is expected to exceed the maximum dose administered in this study. For clinically relevant effect, further studies are warranted, including earlier line of exposure to BVAC-B as well as combination treatments. Clinical trial information: NCT03425773 .

Several COVID-19 platforms have been licensed across the world thus far, but vaccine platform research that can lead to effective antigen delivery is still ongoing. Here, we constructed AdCLD-CoV19 that could modulate humoral immunity by harboring SARS-CoV-2 antigens onto a chimeric adenovirus 5/35 platform that was effective in cellular immunity. By replacing the S1/S2 furin cleavage sequence of the SARS-CoV-2 Spike (S) protein mounted on AdCLD-CoV19 with the linker sequence, high antigen expression was confirmed in various cell lines. The high levels of antigen expression contributed to antigen-specific antibody activity in mice and non-human primates (NHPs) with a single vaccination of AdCLD-CoV19. Furthermore, the adenovirus-induced Th1 immune response was specifically raised for the S protein, and these immune responses protected the NHP against live viruses. While AdCLD-CoV19 maintained neutralizing antibody activity against various SARS-CoV-2 variants, it was reduced to single vaccination for β and ο variants, and the reduced neutralizing antibody activity was restored with booster shots. Hence, AdCLD-CoV19 can prevent SARS-CoV-2 with a single vaccination, and the new vaccine administration strategy that responds to various variants can maintain the efficacy of the vaccine.

Purpose BVAC-B is an autologous B cell– and monocyte-based immunotherapeutic vaccine that contains cells transfected with a recombinant human epidermal growth factor receptor 2 (<i>HER2</i>) gene and loaded with the natural killer T cell ligand alpha-galactosylceramide. Here, we report the first BVAC-B study in patients with HER2-positive advanced gastric cancer.Materials and Methods Patients with advanced gastric cancer refractory to standard treatment with HER2+ immunohistochemistry ≥ 1 were eligible for treatment. Patients were administered low (2.5×10⁷ cells/dose), medium (5.0×10⁷ cells/dose), or high dose (1.0×10⁸ cells/dose) of BVAC-B intravenously four times every 4 weeks. Primary endpoints included safety and maximum tolerated BVAC-B dose. Secondary endpoints included preliminary clinical efficacy and BVAC-B-induced immune responses.Results Eight patients were treated with BVAC-B at low (n=1), medium (n=1), and high doses (n=6). No dose-limiting toxicity was observed, while treatment-related adverse events (TRAEs) were observed in patients treated with medium and high doses. The most common TRAEs were grade 1 (n=2) and grade 2 (n=2) fever. Out of the six patients treated with high-dose BVAC-B, three had stable disease with no response. Interferon gamma, tumor necrosis factor-α, and interleukin-6 increased after BVAC-B treatment in all patients with medium and high dose, and HER2-specific antibody was detected in some patients.Conclusion BVAC-B monotherapy had a safe toxicity profile with limited clinical activity; however, it activated immune cells in heavily pretreated patients with HER2-positive gastric cancer. Earlier treatment with BVAC-B and combination therapy is warranted for evaluation of clinical efficacy.