Comparison of SB17 and reference ustekinumab in healthy adults: A randomized, double-blind, single-dose, phase I study.

OBJECTIVE: This study compared the pharmacokinetic (PK) characteristics of SB17 (Samsung Bioepis, Incheon, Republic of Korea), a proposed biosimilar of ustekinumab (UST) against reference UST (Stelara, Janssen Biotech, Horsham, PA, USA). MATERIALS AND METHODS: This double-blind, three-arm, parallel-group, single-dose study randomized 201 healthy adult subjects 1 : 1 : 1 to receive 45 mg of SB17, European Union-sourced UST (EU-UST) or United States of America-sourced UST (US-UST) via subcutaneous (SC) injection. Primary endpoints were area under the concentration-time curve from time zero to infinity (AUCinf) and maximum serum concentration (Cmax). Safety, tolerability, and immunogenicity were investigated. RESULTS: All 90% confidence intervals (CIs) for the ratios of AUCinf and Cmax between groups were within the predefined bioequivalence margin of 0.8 - 1.25. The geometric LSMeans ratios of AUCinf and Cmax were 0.99 and 0.90 for SB17/EU-UST, 1.01 and 0.94 for SB17/US-UST, and 1.02 and 1.05 for EU-UST/US-UST, respectively. The proportion of subjects with treatment-emergent adverse events (TEAEs) was comparable between SB17, EU-UST, and US-UST (68.7, 58.2, and 65.7%). No deaths, serious adverse events (SAEs), or severe TEAEs were reported. The incidence of subjects testing positive for post-dose anti-drug antibodies (ADAs) was 26.9%, 34.3%, and 34.3% in the SB17, EU-UST, and US-UST groups, respectively. Among the subjects with a positive ADA result at day 99/end of study, 53.8% (SB17 n = 5, EU-UST n = 12, and US-UST n = 11) were positive for neutralizing antibodies (NAbs). CONCLUSION: This study demonstrated bioequivalence of SB17, EU-UST, and US-UST in terms of PK. Safety, tolerability, and immunogenicity were also comparable between all groups.

Enhanced Immunogenicity of Engineered HER2 Antigens Potentiates Antitumor Immune Responses.

For cancer vaccines, the selection of optimal tumor-associated antigens (TAAs) that can maximize the immunogenicity of the vaccine without causing unwanted adverse effects is challenging. In this study, we developed two engineered Human epidermal growth factor receptor 2 (HER2) antigens, K965 and K1117, and compared their immunogenicity to a previously reported truncated HER2 antigen, K684, within a B cell and monocyte-based vaccine (BVAC). We found that BVAC-K965 and BVAC-K1117 induced comparable antigen-specific antibody responses and antigen-specific T cell responses to BVAC-K684. Interestingly, BVAC-K1117 induced more potent antitumor activity than the other vaccines in murine CT26-HER2 tumor models. In addition, BVAC-K1117 showed enhanced antitumor effects against truncated p95HER2-expressing CT26 tumors compared to BVAC-K965 and BVAC-K684 based on the survival analysis by inducing T cell responses against intracellular domain (ICD) epitopes. The increased ICD epitope-specific T cell responses induced by BVAC-K1117 compared to BVAC-K965 and BVAC-K684 were recapitulated in human leukocyte antigen (HLA)-untyped human PBMCs and HLA-A*0201 PBMCs. Furthermore, we also observed synergistic antitumor effects between BVAC-K1117 and anti-PD-L1 antibody treatment against CT26-HER2 tumors. Collectively, our findings demonstrate that inclusion of a sufficient number of ICD epitopes of HER2 in cellular vaccines can improve the antitumor activity of the vaccine and provide a way to optimize the efficacy of anticancer cellular vaccines targeting HER2.

GITR Agonism Triggers Antitumor Immune Responses through IL21-Expressing Follicular Helper T Cells.

Although treatment with the glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) agonistic antibody (DTA-1) has shown antitumor activity in various tumor models, the underlying mechanism is not fully understood. Here, we demonstrate that interleukin (IL)-21-producing follicular helper T (Tfh) cells play a crucial role in DTA-1-induced tumor inhibition. The administration of DTA-1 increased IL21 expression by Tfh cells in an antigen-specific manner, and this activation led to enhanced antitumor cytotoxic T lymphocyte (CTL) activity. Mice treated with an antibody that neutralizes the IL21 receptor exhibited decreased antitumor activity when treated with DTA-1. Tumor growth inhibition by DTA-1 was abrogated in Bcl6 fl/fl Cd4 Cre mice, which are genetically deficient in Tfh cells. IL4 was required for optimal induction of IL21-expressing Tfh cells by GITR costimulation, and c-Maf mediated this pathway. Thus, our findings identify GITR costimulation as an inducer of IL21-expressing Tfh cells and provide a mechanism for the antitumor activity of GITR agonism.

GM-CSF Promotes Antitumor Immunity by Inducing Th9 Cell Responses.

GM-CSF as an adjuvant has been shown to promote antitumor immunity in mice and humans; however, the underlying mechanism of GM-CSF-induced antitumor immunity remains incompletely understood. In this study, we demonstrate that GM-CSF potentiates the efficacy of cancer vaccines through IL9-producing Th (Th9) cells. GM-CSF selectively enhanced Th9 cell differentiation by regulating the COX2-PGE2 pathway while inhibiting the differentiation of induced regulatory T (iTreg) cells in vitro and in vivo GM-CSF-activated monocyte-derived dendritic cells converted tumor-specific naïve Th cells into Th9 cells, and delayed tumor growth by inducing antitumor CTLs in an IL9-dependent manner. Our findings reveal a mechanism for the adjuvanticity of GM-CSF and provide a rationale for the use of GM-CSF in cancer vaccines.