Abstract: The significance of antibody-identified epitopes stimulating humoral alloimmunity is not well understood in the identification of non-permissive human leukocyte antigen (HLA) mismatching patterns in hematopoietic stem cell transplantation (HSCT). This was a retrospective study in a cohort of 9,991 patients who underwent their first HSCT for hematologic malignancies from unrelated bone marrow donors in the Transplant Registry Unified Management Program (TRUMP). HLA eplet mismatches (EMM) were quantified using HLAMatchmaker (HLAMM). The median age of patients was 48 years (range, 16 to 77). The number of EMM in recipient-donor pairs in our study population ranged from 0 to 37 in HLA class I (median, 0) and 0 to 60 in HLA class II (median, 1). In addition to the known high-risk mismatch patterns in the Japanese cohort, HLA-C EMM in the GVH direction was associated with a significantly higher risk for grade III-IV aGVHD, leading to a higher risk of non-relapse mortality and lower overall survival (compared with HLA-C matched patients, HR 1.67, 95% CI 1.44–1.95; HR 1.39, 95% CI 1.25–1.54; HR 1.20, 95% CI 1.10–1.30, respectively). HLAMM-based epitope matching might be useful for identifying patients who are at high risk for serious complications after HSCT from HLA mismatched unrelated donors.

Abstract: For patients with malignant hematological diseases that relapse after allogeneic hematopoietic stem cell transplantation (HSCT), a second HSCT is thought to be a curative option. A second donor is usually searched for due to HLA discrepancy between the graft and the host. However, it is unclear whether HLA discrepancy between the graft and the first donor has an impact on the outcome of second HSCT. To address this issue, we focused on second HSCT patients who had received first HSCT from an HLA-mismatched (MM) donor and compared the effects of HLA discrepancy between graft and first donor with those between graft and host. We retrospectively analyzed 646 patients receiving second HSCT between 1994 and 2016 after an initial HLA-MM transplantation. With regard to the graft versus host results, the one-allele mismatch (1 MM) group (relative risk [RR], 1.88; 95% confidence interval [CI] , 0.79-4.45; p=0.163) and more than one-allele mismatch group (≥ 2 MM) (RR, 1.84; 95% CI, 0.75-4.51; p=0.182) had higher risks of grade III-IV acute GVHD compared to the HLA-matched (0 MM) group, although the results were not significant. In contrast, almost no difference in risk of acute GVHD was found among the 0, 1, and ≥ 2 MM group with respect to graft vs. first donor. Furthermore, with regard to graft vs. host, the ≥ 2 MM group showed a significantly higher risk of treatment-related mortality (TRM) (RR, 1.90; 95% CI, 1.04-3.50; p=0.038) compared to the 0 MM group. In contrast, the risk of relapse was slightly lower in the ≥ 2 MM group (RR, 068; 95% CI, 0.44-1.06; p=0.086). Consequently, no significant difference in OS was found among the three groups. In the analysis of each HLA allele MM, B allele MM between graft and host was associated with an increased risk of grade III-IV acute GVHD (RR 2.87; 95% CI, 1.42-5.79; p=0.003) and DR allele MM between graft and host was associated with a lower risk of relapse (RR, 0.75; 95% CI, 0.58-0.95; p=0.018) and higher risk of TRM (RR, 1.44; 95% CI, 1.03-2.00; p=0.033). In contrast, with regard to graft vs. first donor, there were no significant differences in relapse, TRM, or OS among the three groups, and also analysis of each HLA allele MM indicated no associations with relapse, TRM, or OS. These findings suggested that HLA discrepancy between graft and host, rather than between graft and first donor may induce transplant-related immunological responses in second HSCT leading to an increase in TRM. In conclusion, HLA-MM donor is an option after initial HLA-MM transplantation, however, TRM remains a challenge, particularly with a ≥ 2 MM donor regarding to graft versus host. In this study, the biological effects of HLA discrepancy between the graft and the first donor on the outcome appeared negligible, and our findings shed light on the role of nonhematopoietic APCs on transplant-related immunological responses. Figure. Figure. Disclosures Nakamae: Otsuka Pharmaceutical Co., Ltd.: Consultancy, Honoraria, Research Funding. Ichinohe:Mundipharma: Honoraria; Eisai Co.: Research Funding; Ono Pharmaceutical Co.: Research Funding; Alexion Pharmaceuticals: Honoraria; Zenyaku Kogyo Co.: Research Funding; Kyowa Hakko Kirin Co.: Research Funding; CSL Behring: Research Funding; Novartis.: Honoraria; Takeda Pharmaceutical Co.: Research Funding; Taiho Pharmaceutical Co.: Research Funding; Chugai Pharmaceutical Co.: Research Funding; Astellas Pharma: Research Funding; Repertoire Genesis Inc.: Research Funding; Sumitomo Dainippon Pharma Co.: Research Funding; Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; JCR Pharmaceuticals: Honoraria; Janssen Pharmaceutical K.K.: Honoraria; Pfizer: Research Funding; Nippon Shinyaku Co.: Research Funding; MSD: Research Funding; Otsuka Pharmaceutical Co.: Research Funding. Kanda:Ono: Consultancy, Honoraria, Research Funding; Shionogi: Consultancy, Honoraria, Research Funding; Nippon-Shinyaku: Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Kyowa-Hakko Kirin: Consultancy, Honoraria, Research Funding; Taiho: Research Funding; Pfizer: Research Funding; Taisho-Toyama: Research Funding; MSD: Research Funding; Novartis: Research Funding; Tanabe-Mitsubishi: Research Funding; Chugai: Consultancy, Honoraria, Research Funding; Otsuka: Research Funding; Dainippon-Sumitomo: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Eisai: Consultancy, Honoraria, Research Funding; Sanofi: Research Funding; CSL Behring: Research Funding; Asahi-Kasei: Research Funding; Celgene: Consultancy, Honoraria; Mochida: Consultancy, Honoraria; Alexion: Consultancy, Honoraria; Takara-bio: Consultancy, Honoraria.

Abstract: Background The immunological effect of human leukocyte antigen (HLA) disparity has not been fully elucidated by the number and locus of HLA antigens or alleles. Several methods to predict epitopes recognized by the immune system have been developed to understand the immunogenicity of amino acid sequences in mismatched HLA pairs. We investigated the association between mismatching of HLA antibody-identified epitopes and hematopoietic stem cell transplantation (HSCT) outcomes. Patients and Methods This was a retrospective cohort study with 9,991 patients who underwent their first HSCT for hematologic malignancies from unrelated bone marrow donors in the Transplant Registry Unified Management Program (TRUMP). HLA epitope mismatches (EMM) were quantified using HLA-matchmaker (HLAMM). We conducted a multivariate analysis using Cox proportional hazard regression for the overall survival and the Fine-Gray regression model for competing risks. Statistical analyses were performed with Stata version 15.1 and R version 4.0.2. Results The median follow-up period for survivors was 6.3 years (interquartile range [IQR], 2.5-9.2 years). The most common indication for HSCT was acute myeloid leukemia (n=3,917, 39.2%), followed by acute lymphoblastic leukemia (n=1,913, 19.2%), and mature lymphoid malignancies (n=1,906, 19.1%). HSCT from HLA-matched, HLA 1 allele mismatched, and HLA 2 or more allele mismatched donors was received by 6,200, 2660, and 1131 patients, respectively. The number of EMM in recipient-donor pairs in our study population ranged from 0 to 37 in HLA class I (median, 0) and 0 to 60 in HLA class II (median, 1). Patients were categorized into two groups, low and high EMM, using the median value for each epitope matching as the threshold. Higher HLA class I EMM in the graft-versus-host (GVH) direction was associated with a significantly higher risk of grade III-IV acute GVHD (aGVHD) (hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.21-2.36). Higher EMM for both class I and class II in the host-versus-graft (HVG) direction was associated with a significantly longer time to neutrophil engraftment (HR 0.78, 95% CI 0.65-0.95). In subgroup analysis limited to HLA 1 allele mismatch, class I high EMM group in the GVH direction had a significant association with higher risk for grade II-IV and grade III-IV aGVHD compared with both class I and class II low-EMM group (HR 1.69, 95% CI 1.16-2.47). Patients with HLA-C EMM accounted for 94.5% (n=1,603) of patients with HLA class I EMM. We further investigated the impact of HLA-C on severe aGVHD in relation to other known high-risk mismatch patterns. All killer immunoglobulin-like receptor (KIR)-ligand mismatched recipient-donor pairs (n=376) had HLA-C EMM. In multivariate analysis, patients with KIR-ligand mismatches and EMM did not show a higher incidence of grade III-IV aGVHD compared with KIR-ligand-matched patients with EMM (HR 0.96, 95% CI 0.74-1.25). In addition to the known high-risk mismatch patterns in the Japanese cohort (Kawase et al. Blood. 2007, Morishima et al. Haematologica. 2016), EMM was associated with a higher risk for grade III-IV aGVHD (Figure 1A, compared with HLA-C allele-matched patients (Match), HLA-C allele-mismatched patients without antigen mismatches, and EMM (group A): HR 0.78, 95% CI 0.41-1.48; HLA-C antigen-mismatched patients without EMM (group B): HR 0.56, 95% CI 0.28-1.15; HLA-C epitope-mismatched patients without high-risk mismatches (group C): HR 1.67, 95% CI 1.44-1.95; Patients with high-risk mismatches other than patient mismatched HLA-C*14:02 (group D): HR 2.01, 95% CI 1.50-2.69; Patients with patient mismatched HLA-C*14:02 (group E): HR 3.38, 95% CI 2.39-4.78). HLA-C epitope-mismatched patients without high-risk mismatches also showed a higher incidence of non-relapse mortality (NRM) and lower overall survival (OS) than HLA-C allele-matched patients (NRM (Figure 1B): HR 1.39, 95% CI 1.25-1.54; OS (Figure 1C): HR 1.20, 95% CI 1.10-1.30). Conclusion HLAMM-based epitope matching might be useful for identifying high-risk groups who can develop serious complications after HSCT from HLA-mismatched unrelated donors. In the HLA-C locus, epitope-mismatched recipient-donor pairs are non-permissive mismatched patterns along with known high-risk amino acid substitutions. Our findings might be helpful for clinicians in selecting permissive donors from alternative donor options. Figure 1 Figure 1. Disclosures Iwasaki: Amgen Astellas BioPharma: Honoraria; Astellas Pharma Inc.: Consultancy, Honoraria; Bristol-Myers Squibb Co: Honoraria; CHUGAI PHARMACEUTICAL Co., Ltd.: Honoraria; DAIICHI SANKYO Co., Ltd.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Eisai: Research Funding; Janssen Pharmaceutical K.K.: Honoraria, Membership on an entity's Board of Directors or advisory committees; Kyowa Kirin Co., Ltd.: Honoraria; Megakaryon Co: Honoraria, Membership on an entity's Board of Directors or advisory committees; NextGeM Inc: Patents & Royalties; Novartis Pharma K.K.: Honoraria; Ono Pharma Inc.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Sanofi K.K.: Honoraria; Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; SymBio Pharmaceuticals, Ltd.: Membership on an entity's Board of Directors or advisory committees; Takeda Pharmaceutical Company Limited: Honoraria, Membership on an entity's Board of Directors or advisory committees; TEIJIN PHARMA LIMTED.: Honoraria. Uchida: Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma Inc.: Honoraria. Kataoka: Ono Pharmaceutical: Honoraria, Research Funding; Celgene: Honoraria; Eisai: Honoraria, Research Funding; Astellas Pharma: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Chugai Pharmaceutical: Honoraria, Research Funding; AstraZeneca: Honoraria; Sumitomo Dainippon Pharma: Honoraria, Research Funding; Kyowa Kirin: Honoraria, Research Funding; Janssen Pharmaceutical: Honoraria; Takeda Pharmaceutical: Honoraria, Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding; Asahi Genomics: Current holder of individual stocks in a privately-held company; Shionogi: Research Funding; Teijin Pharma: Research Funding; Japan Blood Products Organization: Research Funding; Bristol-Myers Squibb: Research Funding; Mochida Pharmaceutical: Research Funding; JCR Pharmaceuticals: Research Funding; MSD: Research Funding. Kanda: MSD: Honoraria; Sanofi: Research Funding; Otsuka Pharmaceutical: Honoraria, Research Funding. Ichinohe: Daiichi Sankyo: Research Funding; Bristol-Myers Squibb: Honoraria; Chugai Pharmaceutical: Research Funding; CSL Behring: Honoraria, Research Funding; Eisai Co.: Honoraria, Research Funding; FUJIFILM Wako Chemicals.: Honoraria, Research Funding; Kyowa Kirin Co.: Honoraria, Research Funding; Ono Pharmaceutical Co.: Honoraria, Research Funding; Nippon Shinyaku Co: Research Funding; Otsuka Pharmaceutical Co.: Research Funding; Sumitomo Dainippon Pharma Co.: Honoraria, Research Funding; Taiho Pharmaceutical Co.: Research Funding; Takara Bio Inc.: Research Funding; Zenyaku Kogyo Co.: Research Funding; Celgene: Honoraria; Novartis Pharma K.K.: Honoraria; Repertoire Genesis Inc.: Honoraria, Research Funding; AbbVie Pharma: Research Funding; Astellas Pharma: Honoraria, Research Funding; Takeda Pharmaceutical Co.: Honoraria. Atsuta: Mochida Pharmaceutical Co., Ltd.: Speakers Bureau; Astellas Pharma Inc.: Speakers Bureau; AbbVie GK: Speakers Bureau; Kyowa Kirin Co., Ltd: Honoraria; Meiji Seika Pharma Co, Ltd.: Honoraria.

Abstract: High blood pressure increases bleeding risk during treatment with antithrombotic medication. The association between blood pressure levels and the risk of recurrent stroke during long-term secondary stroke prevention with thienopyridines (particularly prasugrel) has not been well studied. Methods: This was a post hoc analysis of the randomized, double-blind, multicenter PRASTRO-I trial (Comparison of Prasugrel and Clopidogrel in Japanese Patients With Ischemic Stroke-I). Patients with noncardioembolic stroke were randomly assigned (1:1) to receive prasugrel 3.75 mg/day or clopidogrel 75 mg/day for 96 to 104 weeks. Risks of any ischemic or hemorrhagic stroke, combined ischemic events, and combined bleeding events were determined based on the mean level and visit-to-visit variability, including successive variation, of systolic blood pressure (SBP) throughout the observational period. These risks were also compared between quartiles of mean SBP level and successive variation of SBP. Results: A total of 3747 patients (age 62.1±8.5 years, 797 women), with a median average SBP level during the observational period of 132.5 mm Hg, were studied. All the risks of any stroke (146 events; hazard ratio, 1.318 [95% CI, 1.094–1.583] per 10-mm Hg increase), ischemic stroke (133 events, 1.219 [1.010–1.466] ), hemorrhagic stroke (13 events, 3.247 [1.660–6.296]), ischemic events (142 events, 1.219 [1.020–1.466] ), and bleeding events (47 events, 1.629 [1.172–2.261]) correlated with increasing mean SBP overall. Similarly, an increased risk of these events correlated with increasing successive variation of SBP (hazard ratio, 3.078 [95% CI, 2.220–4.225] per 10-mm Hg increase; 3.051 [2.179–4.262]; 3.276 [1.172–9.092] ; 2.865 [2.042–4.011]; 2.764 [1.524–5.016] , respectively). Event rates did not differ between the clopidogrel and prasugrel groups within each quartile of SBP or successive variation of SBP. Conclusions: Both high mean SBP level and high visit-to-visit variability in SBP were significantly associated with the risk of recurrent stroke during long-term medication with either prasugrel or clopidogrel after stroke. Control of hypertension would be important regardless of the type of antiplatelet drugs. Registration: URL: https://www.clinicaltrials.jp ; Unique identifier: JapicCTI-111582.

Abstract: Mechanisms underpinning the dysfunctional immune response in severe acute respiratory syndrome coronavirus 2 infection are elusive. We analyzed single-cell transcriptomes and T and B cell receptors (BCR) of 〉 895,000 peripheral blood mononuclear cells from 73 coronavirus disease 2019 (COVID-19) patients and 75 healthy controls of Japanese ancestry with host genetic data. COVID-19 patients showed a low fraction of nonclassical monocytes (ncMono). We report downregulated cell transitions from classical monocytes to ncMono in COVID-19 with reduced CXCL10 expression in ncMono in severe disease. Cell–cell communication analysis inferred decreased cellular interactions involving ncMono in severe COVID-19. Clonal expansions of BCR were evident in the plasmablasts of patients. Putative disease genes identified by COVID-19 genome-wide association study showed cell type-specific expressions in monocytes and dendritic cells. A COVID-19-associated risk variant at the IFNAR2 locus (rs13050728) had context-specific and monocyte-specific expression quantitative trait loci effects. Our study highlights biological and host genetic involvement of innate immune cells in COVID-19 severity.

Abstract: Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge 1–5 . Here we conducted a genome-wide association study (GWAS) involving 2,393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3,289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene ( DOCK2 ), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis ( n  = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target.