Allogeneic Organ Transplantation Research Articles

Unlocking Transplant Tolerance with Biomaterials.

For patients suffering from organ failure due to injury or autoimmune disease, allogeneic organ transplantation with chronic immunosuppression is considered the god standard in terms of clinical treatment. However, the true "holy grail" of transplant immunology is operational tolerance, in which the recipient exhibits a sustained lack of alloreactivity toward unencountered antigen presented by the donor graft. This outcome is resultant from critical changes to the phenotype and genotype of the immune repertoire predicated by the activation of specific signaling pathways responsive to soluble and mechanosensitive cues. Biomaterials have emerged as a medium for interfacing with and reprogramming these endogenous pathways toward tolerance in precise, minimally invasive, and spatiotemporally defined manners. By viewing seminal and contemporary breakthroughs in transplant tolerance induction through the lens of biomaterials-mediated immunomodulation strategies-which include intrinsic material immunogenicity, the depot effect, graft coatings, induction and delivery of tolerogenic immune cells, biomimicry of tolerogenic immune cells, and in situ reprogramming-this review emphasizes the stunning diversity of approaches in the field and spotlights exciting future directions for research to come.

Comparison of Long-Term Outcomes of Surgical Treatment of Human Papillomavirus-Dependent Neoplastic Lesions in Patients With Chronic Immunosuppression After Allogenic Organ Transplantation and Patients With Primary or Acquired Immunodeficiency—A One-Center Experience

Immunodeficiency predisposes to severe manifestations of human papillomavirus (HPV) infection, including extensive, recalcitrant anogenital lesions and their progression towards carcinomas. This holds for primary and acquired immunodeficiencies, and post-transplant immunosuppressive therapy. About 50% to 90% of patients receiving chronic immunosuppression after allogenic transplantation develop HPV-associated lesions within 4 to 5 years, comprising 10% to 15% of patients presenting with (pre)cancerous HPV-dependent anogenital lesions. Immunodeficiency is one of the highest risk factors associated with severe clinical manifestations of HPV-associated cancers. The primary objective of this work is to compare the long-term therapeutic effectiveness of surgical intervention for HPV-dependent lesions in transplant recipients undergoing chronic immunosuppression and patients burdened with primary or acquired immunodeficiencies. Two groups of 30 patients (selected for most extensive presentations of HPV-dependent neoplastic anogenital lesions), who underwent surgical treatment of these lesions were followed up for 3 to 5 years. The first group comprised patients who qualified and underwent kidney or liver transplantation (10 for a rare disease indication) and are under chronic immunosuppressive regimens. The second group comprised patients burdened by primary or acquired immunodeficiency (15 each). The recurrence rate in the follow-up period was the primary compared parameter. The recurrence rate was higher in the second group, amounting to >15%. For the first group a <5% recurrence rate was observed for recipients without rare disease indications, compared to <15% for recipients with such indications. The importance of rapid surgical intervention and the need for postoperative monitoring for recurrence is highlighted. Chronic immunosuppression demonstrates high relative safety and efficacy in terms of HPV-dependent anogenital lesion recurrence.

Mechanism Exploration on the Immunoregulation of Allogeneic Heart Transplantation Rejection in Rats With Exosome miRNA and Proteins From Overexpressed IDO1 BMSCs.

Immunoregulation and indoleamine 2,3-dioxygenase 1 (IDO1) play pivotal roles in the rejection of allogeneic organ transplantation. This study aims to elucidate the immune-related functional mechanisms of exosomes (Exos) derived from bone marrow-derived mesenchymal stem cells (BMSCs) overexpressing IDO1 in the context of allogeneic heart transplantation (HTx) rejection. A rat model of allogeneic HTx was established. Exos were extracted after transfection with oe-IDO1 and oe-NC from rat BMSCs. Exos were administered via the caudal vein for treatment. The survival of rats was analyzed, and reverse transcription qualitative PCR (RT-qPCR) and immunohistochemistry (IHC) were employed to detect the expression of related genes. Histopathological examination was conducted using hematoxylin and eosin (HE) staining, and flow cytometry was utilized to analyze T-cell apoptosis. Proteomics and RNA-seq analyses were performed on Exos. The data were subjected to functional enrichment analysis using the R language. A protein interaction network was constructed using the STRING database, and miRWalk, TargetScan, and miRDB databases predicted the target genes, differentially expressed miRNAs, and transcription factors (TFs). Exos from BMSCs overexpressing IDO1 prolonged the survival time of rats undergoing allogeneic HTx. These Exos reduced inflammatory cell infiltration, mitigated myocardial damage, induced CD4 T-cell apoptosis, and alleviated transplantation rejection. The correlation between Exos from BMSCs overexpressing IDO1 and immune regulation was profound. Notably, 13 immune-related differential proteins (Anxa1, Anxa2, C3, Ctsb, Hp, Il1rap, Ntn1, Ptx3, Thbs1, Hspa1b, Vegfc, Dcn, and Ptpn11) and 10 significantly different miRNAs were identified. Finally, six key immune proteins related to IDO1 were identified through common enrichment pathways, including Thbs1, Dcn, Ptpn11, Hspa1b, Il1rap, and Vegfc. Thirteen TFs of IDO1-related key miRNAs were obtained, and a TF-miRNA-mRNA-proteins regulatory network was constructed. Exosome miRNA derived from BMSCs overexpressing IDO1 may influence T-cell activation and regulate HTx rejection by interacting with mRNA.

Tacrolimus Pharmacotherapy: Infectious Complications and Toxicity in Organ Transplant Recipients; An Updated Review.

After allogeneic organ transplantation, in order to reduce the risk of rejection, tacrolimus is given. In fact, infection is reported as one of the most common side effects of tacrolimus that might be associated with graft failure. This study aims to review the association between the occurrence of infections due to toxicity following the administration of tacrolimus in organ transplant recipients. Scientific literature on the pharmacotherapy of tacrolimus after organ transplantation, infections, and neurotoxicity were searched using PUBMED.Gov (https://pubmed.ncbi.nlm.nih.gov/), Web of Science, and Scopus (n=108). All articles were screened, and the data associated with the topic of interest was extracted. The primary outcome was infection and neurotoxicity. Total area under the curve exposure, the ratio of parent drug/metabolites of tacrolimus was reported to be correlated with aggressive events such as infection episodes. A trough/dose ratio may demonstrate the net state of immunosuppression and drug-related events. The most frequent infectious complication of tacrolimus after organ transplantation was reported as urinary tract infections (UTIs). Virulent strains of recombinant Listeria monocytogenes, in addition to an increase in bacterial burden in the liver and spleen tissues, were reported in experimental animal studies. Patient survival was significantly lower in recipients with UTIs in the first post-transplant month. A higher degree of immunosuppression was associated with recurrent UTIs and drug-resistant organisms. By inhibiting the cerebral immune system, tacrolimus could cause neurodegeneration. Transplant type, gut dysmotility, acute or chronic condition before transplant surgery, use of azole, antifungal, hematocrit, tacrolimus methods of detection, the total area under the curve, and duration of hospital stay could define the risk of infection through the first month of transplant surgery. In addition, neurological and infectious complications could be associated with the higher amounts of tacrolimus trough levels (C0). Polypharmacy based on tacrolimus, antiviral, and antifungal drugs, in addition to neurotoxicity, could increase the risk of opportunistic infections such as cytomegalovirus within the first year of organ transplantation.

Pushing the boundaries of innovation: the potential of ex vivo organ perfusion from an interdisciplinary point of view.

Ex vivo machine perfusion (EVMP) is an emerging technique for preserving explanted solid organs with primary application in allogeneic organ transplantation. EVMP has been established as an alternative to the standard of care static-cold preservation, allowing for prolonged preservation and real-time monitoring of organ quality while reducing/preventing ischemia-reperfusion injury. Moreover, it has paved the way to involve expanded criteria donors, e.g., after circulatory death, thus expanding the donor organ pool. Ongoing improvements in EVMP protocols, especially expanding the duration of preservation, paved the way for its broader application, in particular for reconditioning and modification of diseased organs and tumor and infection therapies and regenerative approaches. Moreover, implementing EVMP for in vivo-like preclinical studies improving disease modeling raises significant interest, while providing an ideal interface for bioengineering and genetic manipulation. These approaches can be applied not only in an allogeneic and xenogeneic transplant setting but also in an autologous setting, where patients can be on temporary organ support while the diseased organs are treated ex vivo, followed by reimplantation of the cured organ. This review provides a comprehensive overview of the differences and similarities in abdominal (kidney and liver) and thoracic (lung and heart) EVMP, focusing on the organ-specific components and preservation techniques, specifically on the composition of perfusion solutions and their supplements and perfusion temperatures and flow conditions. Novel treatment opportunities beyond organ transplantation and limitations of abdominal and thoracic EVMP are delineated to identify complementary interdisciplinary approaches for the application and development of this technique.

Case report on prolonged kidney graft survival without immunosuppressive therapy after allogeneic hematopoietic stem cell transplantation

Background. The possibility of inducing immunological tolerance in allogeneic organ transplant recipients is a research goal of the transplantology community, as it will ensure the likelihood of complete engraftment of a foreign organ. However, such a task presently remains difficult to accomplish.Objective: to demonstrate longterm kidney graft survival without signs of acute rejection and without immunosuppressive therapy in a patient who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) from a haploidentical donor for post-transplant lymphoproliferative disorder (PTLD).Methods and materials. Recipient’s graft function was assessed using clinical, laboratory, instrumental and pathomorphological examination methods. Results. With no immunosuppressive therapy for more than four years, the kidney recipient showed stable, satisfactory graft function.Conclusion. The described clinical case demonstrates the development of immunological tolerance to a kidney graft in a recipient of allogeneic hematopoietic stem cells (HSCs).

Dynamic monitoring of ctDNA to predict response to immunotherapy plus chemotherapy in BTC.

e14550 Background: The survival of advanced BTC patients, especially those who received palliative surgery was unfavorable and the treatment options for these patients were limited. Immune checkpoint inhibitors （ICIs） were approved for the treatment for patients with BTC. However, only a subset of patients benefits from this treatment and the clinical performance was not well evaluated. Therefore, there is a need for a method that can promptly and dynamically evaluate the efficacy of patients receiving immunotherapy. Previous studies have shown that ctDNA can detect relapse and monitor therapeutic efficacy in diverse cancer. We performed a retrospective observational study examining whether ctDNA could serve as a biomarker to track treatment responses in BTC. Methods: Patients diagnosed with advanced BTC and who received ICI were screened and enrolled between January 2020 and October 2022 at Shanghai Eastern Hepatobiliary Surgery Hospital. The key inclusion criteria for patients were as follows: a recent diagnosis of gallbladder/intrahepatic cholangiocarcinoma; received immunotherapy (or plus target therapy); received ctDNA NGS monitoring. Patients were excluded based on the following criteria: patients with multiple primary cancers, or had history of allogeneic organ transplantation or allogeneic hematopoietic stem cell transplantation, or HIV infected person, or severe infections with poor clinical control. Blood samples were collected for ctDNA analysis at the beginning, after 3 and 6 months of ICI treatment. Results: The median age was 66 (42-79), and 12 (44.4%) were male. The ECOG score was mostly 1 (23 cases, 85.2%). Most of the patients were stage IV (21, 77.8%), and there were 5 (18.5%) stage III patients, 1 (3.7%) stage II and 0 (0%) stage I patients. The BTC patients were mostly histologically diagnosed with gallbladder cancer (GBC, 11, 40.7%) and intrahepatic cholangiocarcinoma (8 cases, 29.63%). There were 55% patients received palliative surgery. Among all mutations detected in ctDNA, the mutation status of KRSA at baseline was detected to be related to patient survival, and the KRAS-mut group had a significantly lower probability of overall survival compared to the KRAS-WT group (p=0.014). Patients with more than 3 new mutations during treatment presented a significantly unfavorable OS (p=0.025) and a trend of unfavorable PFS (p=0.062). Besides, patients with increasing amounts of total ctDNA during dynamic monitoring showed significantly worse overall survival probability (p=0.023). Conclusions: Mutation of KRAS in tissues at baseline might be a predictive marker of response to immunotherapy and survival prognosis. ctDNA as a compose biomarker can monitor treatment responses and predict overall survival. Considering the small size and the relatively short follow-up time of our cohort, further prospective and randomized controlled studies are indispensable.

Abstract CT129: Trial in progress: ATHENA-1 - a phase 1, open-label, first-in-human study to assess safety and tolerability of REGN5837 in combination with odronextamab in patients with relapsed/refractory aggressive B-cell non-Hodgkin lymphomas

Abstract Background: Many patients with relapsed/refractory (R/R) aggressive B-cell non-Hodgkin lymphoma (B-NHL) are unable to tolerate, access, or benefit from intensive chemo-therapeutic approaches or cellular therapies and will invariably relapse; therefore, novel approaches are urgently required. Odronextamab (REGN1979) is a hinge-stabilized, human CD20 × CD3 IgG4-based bispecific antibody that elicits T-cell-mediated cytotoxicity of malignant B cells. In a Phase 1 study, odronextamab monotherapy showed a manageable safety profile with encouraging preliminary activity in heavily pre-treated patients with R/R B-NHL (Bannerji R, et al. Lancet Haematol. 2022;9(5):e327-39). REGN5837 is a hinge-stabilized, human CD28 × CD22 IgG4-based bispecific antibody that provides a co-stimulatory signal (signal 2). When combined with odronextamab (signal 1), REGN5837 improved anti-tumor efficacy and survival in in vivo diffuse large B-cell lymphoma tumor models via enhanced T-cell expansion. We hypothesize that combining REGN5837 with odronextamab may deepen and extend anti-tumor activity in patients with aggressive lymphoma. Methods: ATHENA-1 (NCT05685173) is a Phase 1, open-label, first-in-human study of REGN5837 in combination with odronextamab in patients with R/R aggressive B-NHL. During induction, odronextamab and REGN5837 will be administered weekly over 21-day cycles. To mitigate potential CRS events, odronextamab will be introduced with step-up dosing as a monotherapy, followed by introduction of REGN5837 on C2 D15 with step-up dosing. Maintenance will consist of 28-day cycles (odronextamab and REGN5837 administration on D1, 15). Patients who achieve a sustained complete response (≥9 months) will have study drug(s) administration changed to once every 4 weeks. Patients must be aged ≥18 years, have Eastern Cooperative Oncology Group performance status ≤1, with adequate organ function, and have CD20+ aggressive B-NHL that progressed after ≥2 lines of systemic therapy containing at least an anti-CD20 antibody and an alkylating agent, with or without prior chimeric antigen receptor T-cell therapy. Exclusion criteria include prior allogeneic stem cell transplant, organ transplant, or CD20xCD3 bispecific antibodies, or mantle cell lymphoma or central nervous system lymphoma. Primary endpoints are incidence of dose-limiting toxicities and the incidence and severity of treatment-emergent adverse events. Secondary endpoints include pharmacokinetics of odronextamab and REGN5837, anti-drug antibody incidence, objective response rate, complete response rate, duration of response, progression-free survival, and overall survival. Enrolment is planned to open in early 2023. Citation Format: John Baird, Pim G. Mutsaers, Jeremy S. Abramson, Manjusha Namuduri, Jingjin Li, Nickolas A. Sophos, Min Zhu, Jurriaan Brouwer-Visser, Hesham Mohamed, Aafia Chaudhry, Andrew J. Davies. Trial in progress: ATHENA-1 - a phase 1, open-label, first-in-human study to assess safety and tolerability of REGN5837 in combination with odronextamab in patients with relapsed/refractory aggressive B-cell non-Hodgkin lymphomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT129.

Phase 1b Trial of Anti-Immunoglobulin-like Transcript 3 Monoclonal Antibody MK-0482 Monotherapy in Relapsed/Refractory Acute Myeloid Leukemia and Chronic Myelomonocytic Leukemia

Background: Immunoglobulin-like transcript 3 (ILT3) is a cell surface inhibitory receptor expressed on various immune cells including dendritic cells, monocytic myeloid cells, and macrophages. The expression of ILT3 on dendritic cells and myeloid cells is thought to be involved in immune suppression and antigen-specific immune tolerance, contributing to an immunosuppressive tumor microenvironment. Acute myeloid leukemia (AML) is a type of cancer characterized by bone marrow that makes a large number of abnormal blood cells. In monocytic AML, ILT3 is highly expressed, and its signaling can mediate T-cell suppression and promote tumor infiltration (Deng M et al. Nature. 2018;562:605-609). Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm characterized by dysplasia, abnormal production and accumulation of monocytic cells, and with an elevated risk of transforming into AML. Based on the M2GEN database, ILT3 is also highly expressed in CMML. Thus, targeting ILT3 may exhibit antitumor activity in patients with AML and CMML. Currently, limited effective treatments are available for AML and CMML, especially in the relapse and refractory setting. MK-0482, a humanized IgG4 anti-ILT3 monoclonal antibody, has been evaluated as monotherapy and in combination with pembrolizumab at doses ≤2250 mg every 3 weeks (Q3W) in patients with advanced solid tumors. Patients treated with MK-0482 had a manageable safety profile, and modest antitumor activity was observed with MK-0482 plus pembrolizumab (Gutierrez M et al. J Clin Oncol. 2022;40. Abstract 2505). In this phase 1b study (NCT05038800), we are evaluating the safety and the pharmacokinetic (PK) and pharmacodynamic (PD) profiles of MK-0482 in relapsed or refractory (r/r) AML and CMML. Study Design and Methods: Adult patients with AML with myelomonocytic or monoblastic/monocytic differentiation or CMML and with confirmed refractory or relapsed disease after treatment with available therapies will be eligible for enrollment. All patients must have an ECOG performance status of 0-2, adequate organ function, and a white blood cell count ≤20 × 109/L. Patients with active central nervous system leukemia, isolated extramedullary disease (ie no leukemic involvement), acute promyelocytic leukemia, or who have previously received allogeneic stem cell or organ transplant <60 days of treatment will be excluded. In part 1 (dose escalation), MK-0482 will be evaluated at dose levels ranging from 7.5 mg to 750 mg Q3W for ≤35 cycles with an accelerated titration design followed by a modified toxicity probability interval design in ~20 patients. After the recommended phase 2 dose (RP2D) is determined, 10 to 15 additional patients with AML with myelomonocytic or monoblastic/monocytic differentiation will be enrolled in part 2 (dose expansion). The primary objective of the study is to determine safety and tolerability and RP2D. Secondary objectives include characterizing the PK profile of MK-0482 monotherapy and antileukemia activities in AML as assessed by complete remission (CR), composite CR, and objective response per the 2017 European Leukemia Net AML response criteria. Exploratory objectives include assessment of receptor occupancy in peripheral blood and tumor biopsies, molecular biomarkers, and antileukemic activities in patients with CMML. Dose-limiting toxicities will be observed for 21 days after the first dose in cycle 1 and adverse events (AEs) will be assessed through 30 days after treatment discontinuation (90 days for serious AEs; 30 days if new anticancer therapy is initiated) per National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.0. Disease assessment will be performed by investigator at baseline and prior to day 1 of cycles 3, 5, and 7, followed by every 3 cycles until disease progression or confirmed CR. Samples for PK analyses will be collected before and after treatment on day 1 of cycles 1-4, 6, 8, and every 4 cycles thereafter. The study is currently ongoing.

Accommodation in allogeneic and xenogeneic organ transplantation: Prevalence, impact, and implications for monitoring and for therapeutics

Accommodation refers to acquired resistance of organs or tissues to immune or inflammatory reactions that might otherwise cause severe injury or rejection. As first observed in ABO-incompatible kidney transplants and heterotopic cardiac xenografts, accommodation was identified when organ transplants continued to function despite the presence of anti-graft antibodies and/or other reactants in the blood of recipients. Recent evidence suggests many and perhaps most organ transplants have accommodation, as most recipients mount B cell responses specific for the graft. Wide interest in the impact of graft-specific antibodies on the outcomes of transplants prompts questions about which mechanisms confer protection against such antibodies, how accommodation might be detected and whether and how rejection could be superimposed on accommodation. Xenotransplantation offers a unique opportunity to address these questions because immune responses to xenografts are easily detected and the pathogenic impact of immune responses is so severe. Xenotransplantation also provides a compelling need to apply these and other insights to decrease the intensity and toxicity of immunosuppression that otherwise could limit clinical application.

Controversial Interactions of Tacrolimus with Dietary Supplements, Herbs and Food

Tacrolimus is an immunosuppressive calcineurin inhibitor used to prevent rejection in allogeneic organ transplant recipients, such as kidney, liver, heart or lung. It is metabolized in the liver, involving the cytochrome P450 (CYP3A4) isoform CYP3A4, and is characterized by a narrow therapeutic window, dose-dependent toxicity and high inter-individual and intra-individual variability. In view of the abovementioned facts, the aim of the study is to present selected interactions between tacrolimus and the commonly used dietary supplements, herbs and food. The review was based on the available scientific literature found in the PubMed, Scopus and Cochrane databases. An increase in the serum concentration of tacrolimus can be caused by CYP3A4 inhibitors, such as grapefruit, pomelo, clementine, pomegranate, ginger and turmeric, revealing the side effects of this drug, particularly nephrotoxicity. In contrast, CYP3A4 inducers, such as St. John’s Wort, may result in a lack of therapeutic effect by reducing the drug concentration. Additionally, the use of Panax ginseng, green tea, Schisandra sphenanthera and melatonin in patients receiving tacrolimus is highly controversial. Therefore, since alternative medicine constitutes an attractive treatment option for patients, modern healthcare should emphasize the potential interactions between herbal medicines and synthetic drugs. In fact, each drug or herbal supplement should be reported by the patient to the physician (concordance) if it is taken in the course of immunosuppressive therapy, since it may affect the pharmacokinetic and pharmacodynamic parameters of other preparations.

The Potential Clinical Application of Induced Tolerogenic Macrophages.

The Potential Clinical Application of Induced Tolerogenic Macrophages.

Abstract CT124: NeoCOAST-2: a randomized, open-label, phase 2 study of neoadjuvant durvalumab plus novel immunotherapies and chemotherapy (CT) followed by adjuvant durvalumab plus novel agents, in patients with resectable non-small-cell lung cancer (NSCLC)

Abstract Background: Neoadjuvant and adjuvant platinum-based CT improve survival rates in patients with resectable, early-stage NSCLC vs surgery alone. PD-1/PD-L1 inhibitors have shown clinical efficacy in patients with resectable, early-stage NSCLC, in both the neoadjuvant and adjuvant settings. The anti-PD-L1 monoclonal antibody (mAb) durvalumab, in combination with either the anti-CD73 mAb oleclumab or the anti-NKG2A mAb monalizumab, improved response rates and progression-free survival in patients with unresectable, Stage III NSCLC in the phase 2 COAST trial (NCT03822351). The NeoCOAST trial (NCT03794544) is currently evaluating the combination of durvalumab with oleclumab or monalizumab as neoadjuvant treatment in patients with resectable, early-stage NSCLC. NeoCOAST-2 (NCT05061550) is a multicenter study of neoadjuvant durvalumab combined with CT and either oleclumab or monalizumab, followed by surgery and adjuvant durvalumab plus oleclumab or monalizumab, in patients with resectable, Stage IIA-IIIA NSCLC. Methods: Eligible patients must have previously untreated, histologically/cytologically confirmed NSCLC, a WHO/ECOG performance status of 0 or 1, and life expectancy of ≥12 weeks. Patients must have tumor samples available for biomarker analyses, have planned surgery consisting of lobectomy, sleeve resection, or bilobectomy, and have a pre- or post-bronchodilator FEV1 of 1.0 L and DLCO &amp;gt;40% postoperative predictive value. Patients with sensitizing EGFR mutations or ALK translocations, history of allogeneic organ transplantation, active or prior documented autoimmune or inflammatory disorders, or uncontrolled intercurrent illness, are excluded. Approximately 140 patients will be randomized 1:1, stratified by PD-L1 expression (&amp;lt;1% vs ≥1%), to receive IV durvalumab + oleclumab or monalizumab + CT Q3W for 4 cycles prior to surgery, followed by durvalumab + oleclumab or monalizumab Q4W post surgery. Surgery must occur within 40 days of the last dose of neoadjuvant therapy. Patients will receive adjuvant therapy starting within 10 weeks after surgery, for 12 cycles or until disease progression (per RECIST v1.1). The primary endpoints are pathological complete response rate per blinded independent pathologist review, and safety and tolerability. Secondary endpoints include investigator-assessed event-free survival and disease-free survival, feasibility of planned surgery, major pathological response rate, changes in circulating tumor DNA, investigator-assessed objective response rate following neoadjuvant therapy, overall survival, pharmacokinetics and immunogenicity. Citation Format: Tina Cascone, Alexander Spira, Rosario G. Campelo, Dong-Wan Kim, Oday Hamid, Yee Soo-Hoo, Rakesh Kumar, Italia Grenga, Patrick Forde. NeoCOAST-2: a randomized, open-label, phase 2 study of neoadjuvant durvalumab plus novel immunotherapies and chemotherapy (CT) followed by adjuvant durvalumab plus novel agents, in patients with resectable non-small-cell lung cancer (NSCLC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT124.

Evaluation of equine xenogeneic mixed lymphocyte reactions using 5-ethynyl-2’-deoxyuridine (EdU)

Allogeneic solid organ transplantation is currently the only treatment option for end stage organ disease. The shortage of available donor organs has driven efforts to utilize xenogeneic organs for transplantation. In vitro methods for evaluating immune-compatibility are a quick and low cost means of screening novel tissue products prior to more involved, expensive, and invasive live animal studies. Recently, a new analog of the DNA base thymidine, 5-ethynyl-2’-deoxyuridine (EdU), was developed. It may be used in a fast, efficient and specific means of evaluating cell proliferation via flow cytometry. This study was designed to test and optimize this platform for assessing equine xenogeneic one-way mixed lymphocyte reaction (MLR) to porcine stimulator cells. Furthermore, it was hypothesized that an enriched T-lymphocyte (T-cell) population would generate a stronger proliferative response to stimulation, and higher levels of cytokine production when compared to unfractionated peripheral blood mononuclear cells (PBMCs). PBMCs and T-cells were isolated from 3 horses and 4 pigs. Equine xenogeneic MLRs were set up using porcine allogeneic MLRs as a reference for clinically acceptable levels of cell proliferation. Equine T-cells showed significantly greater EdU incorporation in one-way xenogeneic MLRs than equine PBMCs. However, there was no significant difference in cell proliferation between porcine T-cell and PBMC as responders in allogenic one-way MLRs. Given the results of this study, we consider that enriched equine T-cells should be used in preference to unfractionated PBMCs when attempting to evaluate the equine xenogeneic response using the EdU assay as an indicator of suitability for transplant in vivo.

Establishment of Chimerism and Organ Transplant Tolerance in Laboratory Animals: Safety and Efficacy of Adaptation to Humans.

The definition of immune tolerance to allogeneic tissue and organ transplants in laboratory animals and humans continues to be the acceptance of the donor graft, rejection of third-party grafts, and specific unresponsiveness of recipient immune cells to the donor alloantigens in the absence of immunosuppressive treatments. Actively acquired tolerance was achieved in mice more than 60 years ago by the establishment of mixed chimerism in neonatal mice. Once established, mixed chimerism was self-perpetuating and allowed for acceptance of tissue transplants in adults. Successful establishment of tolerance in humans has now been reported in several clinical trials based on the development of chimerism after combined transplantation of hematopoietic cells and an organ from the same donor. This review examines the mechanisms of organ graft acceptance after establishment of mixed chimerism (allo-tolerance) or complete chimerism (self-tolerance), and compares the development of graft versus host disease (GVHD) and graft versus tumor (GVT) activity in complete and mixed chimerism. GVHD, GVT activity, and complete chimerism are also discussed in the context of bone marrow transplantation to treat hematologic malignancies. The roles of transient versus persistent mixed chimerism in the induction and maintenance of tolerance and organ graft acceptance in animal models and clinical studies are compared. Key differences in the stability of mixed chimeras and tolerance induction in MHC matched and mismatched rodents, large laboratory animals, and humans are examined to provide insights into the safety and efficacy of translation of results of animal models to clinical trials.

The Significance of RHD Genotyping and Characteristic Analysis in Chinese RhD Variant Individuals.

BackgroundRhD is the most important and complex blood group system because of its highly polymorphic and immunogenic nature. RhD variants can induce immune response by allogeneic transfusion, organ transplantation, and fetal immunity. The transfusion strategies are different for RhD variants formed by various alleles. Therefore, extensive investigation of the molecular mechanism underlying RhD variants is critical for preventing immune-related blood transfusion reactions and fetal immunity.MethodsRhD variants were collected from donors and patients in Zhejiang Province, China. The phenotypes were classified using the serologic method. The full coding regions of RHD gene were analyzed using the PCR-SBT method. The multiplex ligation-dependent probe amplification (MLPA) assay was used to analyze the genotype and gene copy number. SWISS-MODLE and PyMOL software were used to analyze 3D structures of RhD caused by the variant alleles. The effect of non-synonymous substitutions was predicted using Polymorphism Phenotyping algorithm (PolyPhen-2), Sorting Intolerant From Tolerant (SIFT), and Protein Variation Effect Analyzer (PROVEAN) software.ResultsIn the collected RhD variants, 28 distinct RHD variant alleles were identified, including three novel variant alleles. RH-MLPA assay is advantageous for determining the copy number of RHD gene. 3D homology modeling predicted that protein conformation was disrupted and may explain RhD epitope differential expression. A total of 14 non-synonymous mutations were determined to be detrimental to the protein structure.DiscussionWe revealed the diversity of RHD alleles present in eastern Chinese RhD variants. The bioinformatics of these variant alleles extended our knowledge of RhD variants, which was crucial for evaluating their impact to guide transfusion support and avoid immune-related blood transfusion reactions.

Erythropoietin Reduces Auto- and Alloantibodies by Inhibiting T Follicular Helper Cell Differentiation.

Although high-affinity IgG auto- and alloantibodies are important drivers of kidney inflammation that can result in ESKD, therapeutic approaches that effectively reduce such pathogenic antibodies remain elusive. Erythropoietin (EPO) has immunomodulatory functions, but its effects on antibody production are unknown. We assessed the effect and underlying mechanisms of EPO/EPO receptor (EPOR) signaling on primary and secondary, T cell-dependent and T-independent antibody formation using in vitro culture systems, murine models of organ transplantation and lupus nephritis, and mice conditionally deficient for the EPOR expressed on T cells or B cells. In wild-type mice, recombinant EPO inhibited primary, T cell-dependent humoral immunity to model antigens and strong, polyclonal stimuli, but did not alter T-independent humoral immune responses. EPO also significantly impaired secondary humoral immunity in a potent allogeneic organ transplant model system. The effects required T cell, but not B cell, expression of the EPOR and resulted in diminished frequencies of germinal center (GC) B cells and T follicular helper cells (TFH). In vitro and in vivo experiments showed that EPO directly prevented TFH differentiation and function via a STAT5-dependent mechanism that reduces CD4+ T cell expression of Bcl6. In lupus models, EPO reduced TFH, GC B cells, and autoantibody production, and abrogated autoimmune glomerulonephritis, demonstrating clinical relevance. In vitro studies verified that EPO prevents differentiation of human TFH cells. Our findings newly demonstrate that EPO inhibits TFH-dependent antibody formation, an observation with potential implications for treating antibody-mediated diseases, including those of the kidney.

Individualized tissue-engineered veins as vascular grafts: A proof of concept study in pig.

Personalized tissue engineered vascular grafts are a promising advanced therapy medicinal product alternative to autologous or synthetic vascular grafts utilized in blood vessel bypass or replacement surgery. We hypothesized that an individualized tissue engineered vein (P-TEV) would make the body recognize the transplanted blood vessel as autologous, decrease the risk of rejection and thereby avoid lifelong treatment with immune suppressant medication as is standard with allogenic organ transplantation. To individualize blood vessels, we decellularized vena cava from six deceased donor pigs and tested them for cellular removal and histological integrity. A solution with peripheral blood from the recipient pigs was used for individualized reconditioning in a perfusion bioreactor for seven days prior to transplantation. To evaluate safety and functionality of the individualized vascular graft in vivo, we transplanted reconditioned porcine vena cava into six pigs and analyzed histology and patency of the graft at different time points, with three pigs at the final endpoint 4-5weeks after surgery. Our results showed that the P-TEV was fully patent in all animals, did not induce any occlusion or stenosis formation and we did not find any signs of rejection. The P-TEV showed rapid recellularization in vivo with the luminal surface covered with endothelial cells. In summary, the results indicate that P-TEV is functional and have potential for use as clinical transplant grafts.

#50: Cytomegalovirus Retinitis Among Pediatric Hematopoietic Stem Cell and Solid Organ Transplantation Recipients: A Contemporary Review

Abstract Background Cytomegalovirus infection can cause significant morbidity and mortality after transplantation. Cytomegalovirus retinitis (CMVR) can be a major complication of tissue invasive CMV disease in transplant recipients. There are little data regarding the contemporary incidence and outcomes of CMVR among pediatric transplant recipients. Methods We performed a retrospective cohort analysis of allogeneic hematopoietic (allo-HCT) and solid organ transplant (SOT) recipients who received medical care at Nationwide Children’s Hospital (NCH) from 1/1/10–11/30/20 and had a diagnosis of CMVR to describe the incidence, timing post-transplant, ocular manifestations, management, and outcomes. Basic demographic and clinical data, pre-transplant donor/recipient CMV serostatus, and post-transplant CMV infection data were collected. Graft-specific CMV surveillance and prophylaxis strategies were performed according to NCH hospital guidelines. During the study period, quantitative plasma CMV PCR assays included copies/mL (2010–2013) and WHO international standard IU/mL (2013–2020). Results During the 10-year study period, 347 patients underwent allo-HCT (N=214) or SOT (N=133; heart N=46, liver N=36, kidney N= 52; 1 patient had concomitant kidney and liver transplantation); median age was 8.6 years [range 0.1–25.9] and 198 (56.5%) were male. In total, 98 patients had CMV DNAemia post-transplant, and CMVR was diagnosed in 3 (HCT=2, SOT=1), for an overall CMVR incidence of 0.86% among all transplant recipients and occurring in 3% of patients with CMV DNAemia. No CMVR was diagnosed in patients without CMV DNAemia. An ophthalmologic examination was performed in 58 (59%) of patients with any DNAemia compared with 67 (27%) of patients without DNAemia. CMVR was diagnosed on funduscopic examination a median of 183 days [range 34–512] post-transplant based on visual symptomatology (N=2) or by routine eye screening prompted by DNAemia (N=1). CMV DNAemia at the time of CMVR was 1,463 copies/mL, 3,000, and 14,204 IU/mL; all patients had prolonged (&amp;gt;3 months) CMV detection before CMVR. One SOT recipient had concomitant pathology confirming CMV gastrointestinal tract disease. Two of the 3 CMVR cases occurred in the setting of genotypic UL94 CMV resistance mutations (A594V, H520Q)(Figure 1). Two patients were already receiving CMV antiviral therapy (maribavir N=1; valganciclovir=1) at the time of CMVR diagnosis. After the CMVR diagnosis, all patients were prescribed systemic foscarnet. Adjunctive therapies included concurrent intravitreal antiviral therapy (ganciclovir N=1; foscarnet N=1) and adoptive immunotherapy with CMV antiviral specific T-cells (N=1, HCT). Improvement of ocular symptoms occurred in 2 patients at 15 and 20 days after starting targeted CMV antiviral therapy; one patient developed permanently impaired vision. Conclusion CMVR remains as an important complication in transplant recipients. Although CMVR incidence was low in our cohort of transplant recipients, it occurred most frequently in cases of CMV resistance, prolonged DNAemia, and led to permanent visual impairment in 1 of 3 patients. The development of resistant CMV may have a role in the occurrence, progression, and severity of CMVR. Additional pediatric-specific data are needed to better characterize CMVR and inform optimal prevention strategies.

Three-dimensional Printing-Driving Liver Therapies.

End-stage liver diseases have long been a threat to human health, and so far, the treatment of these diseases lacks effective means. Allogenic organ transplantation has become the last straw for most of the patients with end-stage liver diseases. However, this technique has been greatly limited by the serious shortage of donors and other factors, such as immune rejection, drug syndrome, and high cost. Recently, the emergence of three-dimensional (3D) bioprinting technologies, together with the magnetic resonance imaging (MRI) and computed tomography (CT) techniques, has driven the rapid growth of this field toward liver therapies. There are several basic requirements for liver 3D bioprinting. From information collection of diseased livers, to 3D printing of liver substitutes (containing the major structural, material and functional characters), and to clinical applications, suitable 'bioinks' and 'bioprinters' have played essential roles. In this review, we highlight the advanced 'bioinks' and 'bioprinters' that have been used for vascularized and innervated liver tissue 3D bioprinting. Further studies for the incorporation of biliary networks in the bioartificial livers have been emphasized. It is expected that when all the bottle-neck problems for liver 3D bioprinting are solved, batch (i.e. mass) and personalized production of bioartificial livers will make it very easy to treat end-stage liver diseases.