Post-transplant Setting Research Articles

Active Tuberculosis After Solid Organ Transplantation in Individuals With Negative Pretransplant QuantiFERON-TB Gold Testing: A Case Series

Active tuberculosis (TB) in solid organ transplant (SOT) recipients most commonly occurs due to reactivation of latent infection and is associated with poor clinical outcomes, including allograft loss and death. National transplant societies, including the American Society of Transplantation, recommend screening for latent TB prior to transplant, with treatment in the peritransplant setting to reduce the subsequent risk of TB reactivation. Though screening is traditionally conducted using laboratory-based assays, such as the QuantiFERON-TB Gold, false negatives may occur in SOT candidates due to anergy from end-stage organ dysfunction, highlighting the need for a multimodal diagnostic approach. In this case series, we describe the clinical characteristics and outcomes of 3 SOT recipients at the University of Pennsylvania with negative pretransplant QuantiFERON-TB Gold testing who subsequently developed active TB in the posttransplant setting, contributing to a growing body of knowledge regarding this challenging population. Each patient experienced a complicated clinical course that arose in part from the lack of diagnosis of TB prior to transplant. Because all had epidemiologic risk factors for TB, the findings of our study highlight the need for more individualized approaches to pretransplant TB screening.

Analysis of Subset Chimerism for MRD-Detection and Pre-Emptive Treatment in AML.

Allogeneic hematopoietic stem cell transplantation (alloHCT) represents the only potentially curative treatment in high-risk AML patients, but up to 40% of patients suffer from relapse after alloHCT. Treatment of overt relapse poses a major therapeutic challenge and long-term disease control is achieved only in a minority of patients. In order to avoid post-allograft relapse, maintenance as well as pre-emptive therapy strategies based on MRD-detection have been used. A prerequisite for the implementation of pre-emptive therapy is the accurate identification of patients at risk for imminent relapse. Detection of measurable residual disease (MRD) represents an effective tool for early relapse prediction in the post-transplant setting. However, using established MRD methods such as multicolor flow cytometry or quantitative PCR, sensitive MRD monitoring is only applicable in about half of the patients with AML and advanced MDS undergoing alloHCT. Donor chimerism analysis, in particular when performed on enriched leukemic stem and progenitor cells, e.g. CD34+ cells, is a sensitive method and has emerged as an alternative option in the post alloHCT setting. In this review, we will focus on the current strategies for lineage specific chimerism analysis, results of pre-emptive treatment using this technology as well as future developments in this field.

Plasmapheresis for Thrombotic Microangiopathy Due to a Post-transplant Lymphoproliferative Disorder

We report a case of thrombotic microangiopathy (TMA) diagnosed in the kidney allograft of a 59-year-old woman who had developed plasmacytoma type monomorphic posttransplant lymphoproliferative disorder (PTLD) 30 years after a simultaneous pancreas and kidney transplant. This report demonstrates a rare etiology of TMA in a kidney allograft occurring in association with PTLD-associated monoclonal gammopathy. The main teaching points are: 1) PTLD may be considered in the work-up of a new TMA in the immunosuppressed post-transplant setting, and 2) a paraprotein-associated condition should be considered as clinically relevant coexistent in a patient with TMA because paraproteins are over-represented in patients with otherwise unexplained TMAs.

Mucosa-Associated Lymphoid Tissue (MALT) Lymphoma in the Gastrointestinal Tract in the Modern Era.

Simple SummaryExtranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma), which is frequently linked to chronic antigenic stimulation, is clinically an indolent B-cell lymphoma. The most common site is the stomach, accounting for 35% of MALT lymphomas, with a strong association with Helicobacter pylori (H. pylori) infection. Although antibiotic eradication is first-line therapy for gastric MALT lymphoma, a recent trend showing increasing H. pylori-negative cases may require different treatment strategies. Intestinal MALT lymphoma, including immunoproliferative small intestinal disease, is relatively rare, and the pathogenesis and therapeutic approach have not been fully elucidated. In addition, the gastrointestinal tract was recently considered a preferable site of Epstein–Barr-virus-negative marginal zone lymphoma in the post-transplant setting. We review the updated clinicopathological features, treatment, and evolving concepts of MALT lymphoma of the gastrointestinal tract.Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) typically arises from sites such as the stomach, where there is no organized lymphoid tissue. Close associations between Helicobacter pylori and gastric MALT lymphoma or Campylobacter jejuni and immunoproliferative small intestinal disease (IPSID) have been established. A subset of tumors is associated with chromosomal rearrangement and/or genetic alterations. This disease often presents as localized disease, requiring diverse treatment approaches, from antibiotic therapy to radiotherapy and immunochemotherapy. Eradication therapy for H. pylori effectively cures gastric MALT lymphoma in most patients. However, treatment strategies for H. pylori-negative gastric MALT lymphoma are still challenging. In addition, the effectiveness of antibiotic therapy has been controversial in intestinal MALT lymphoma, except for IPSID. Endoscopic treatment has been noted to usually achieve complete remission in endoscopically resectable colorectal MALT lymphoma with localized disease. MALT lymphoma has been excluded from post-transplant lymphoproliferative disorders with the exception of Epstein–Barr virus (EBV)-positive marginal zone lymphoma (MZL). We also describe the expanding spectrum of EBV-negative MZL and a close association of the disease with the gastrointestinal tract.

Immunotherapy in liver transplantation for hepatocellular carcinoma: Pros and cons.

Liver transplantation (LT) has emerged as a curative strategy for hepatocellular carcinoma (HCC), but contributes to a higher predisposition to HCC recurrence in the immunosuppression context, especially for tumors beyond the Milan criteria. Although immunotherapy has dramatically improved survival for immunocompetent patients and has become the standard of care for a variety of tumors, including HCC, it is mainly used outside the scope of organ transplantation owing to potentially fatal allograft rejection. Nevertheless, accumulative evidence has expanded the therapeutic paradigms of immunotherapy for HCC, from downstaging or bridging management in the pretransplant setting to the salvage or adjuvant strategy in the posttransplant setting. Generally, immunotherapy mainly includes immune checkpoint inhibitors (ICIs), adoptive cell transfer (ACT) and vaccine therapy. ICIs, followed by ACT, have been most investigated in LT, with some promising results. Because of the complex tumor microenvironment and immunoreactivity when immunosuppressants are combined with immunotherapy, it is difficult to reach formulations for immunosuppressant adjustment and the optimal selection of immunotherapy as well as patients. In addition, the absence of effective biomarkers for identifying rejection and tumor response is still an unresolved barrier to successful clinical immunotherapy applications for LT. In this review, we comprehensively summarize the available evidence of immunotherapy used in LT that is specific to HCC. Moreover, we discuss clinically concerning issues regarding the concurrent goals of graft protection and antitumor response.

Application of machine learning in liver transplantation: a review.

Machine learning (ML) has been increasingly applied in the health-care and liver transplant setting. The demand for liver transplantation continues to expand on an international scale, and with advanced aging and complex comorbidities, many challenges throughout the transplantation decision-making process must be better addressed. There exist massive datasets with hidden, non-linear relationships between demographic, clinical, laboratory, genetic, and imaging parameters that conventional methods fail to capitalize on when reviewing their predictive potential. Pre-transplant challenges include addressing efficacies of liver segmentation, hepatic steatosis assessment, and graft allocation. Post-transplant applications include predicting patient survival, graft rejection and failure, and post-operative morbidity risk. In this review, we describe a comprehensive summary of ML applications in liver transplantation including the clinical context and how to overcome challenges for clinical implementation. Twenty-nine articles were identified from Ovid MEDLINE, MEDLINE Epub Ahead of Print and In-Process and Other Non-Indexed Citations, Embase, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials. ML is vastly interrogated in liver transplantation with promising applications in pre- and post-transplant settings. Although challenges exist including site-specific training requirements, the demand for more multi-center studies, and optimization hurdles for clinical interpretability, the powerful potential of ML merits further exploration to enhance patient care.

Hypomethylating Agent-Based Combination Therapies to Treat Post-Hematopoietic Stem Cell Transplant Relapse of Acute Myeloid Leukemia

Allogeneic stem cell transplantation still represents the best curative option for most patients with acute myeloid leukemia, but relapse is still dramatically high. Due to their immunologic activity and safety profile, hypomethylating agents (HMAs) represent an interesting backbone for combination therapies. This review reports mechanism of action, safety, and efficacy data on combination strategies based on HMAs in the setting of post-allogeneic stem cell transplant relapse. Several studies highlighted how HMAs and donor lymphocyte infusion (DLI) combination may be advantageous. The combination strategy of HMA with venetoclax, possibly in association with DLI, is showing excellent results in terms of response rate, including molecular responses. Lenalidomide, despite its well-known high rates of severe graft-versus-host disease in post-transplant settings, is showing an acceptable safety profile in association with HMAs with a competitive response rate. Regarding FLT3 internal tandem duplication (ITD) mutant AML, tyrosine kinase inhibitors and particularly sorafenib have promising results as monotherapy and in combination with HMAs. Conversely, combination strategies with gemtuzumab ozogamicin or immune checkpoint inhibitors did not show competitive response rates and seem to be currently less attractive strategies. Associations with histone deacetylase inhibitors and isocitrate dehydrogenase 1 and 2 (IDH1/2) inhibitors represent new possible strategies that need to be better investigated.

Prevention and Treatment of Acute Myeloid Leukemia Relapse after Hematopoietic Stem Cell Transplantation: The State of the Art and Future Perspectives.

Allogeneic hematopoietic stem cell transplantation (HSCT) for high-risk acute myeloid leukemia (AML) represents the only curative option. Progress has been made in the last two decades in the pre-transplant induction therapies, supportive care, selection of donors and conditioning regimens that allowed to extend the HSCT to a larger number of patients, including those aged over 65 years and/or lacking an HLA-identical donor. Furthermore, improvements in the prophylaxis of the graft-versus-host disease and of infection have dramatically reduced transplant-related mortality. The relapse of AML remains the major reason for transplant failure affecting almost 40–50% of the patients. From 10 to 15 years ago to date, treatment options for AML relapsing after HSCT were limited to conventional cytotoxic chemotherapy and donor leukocyte infusions (DLI). Nowadays, novel agents and targeted therapies have enriched the therapeutic landscape. Moreover, very recently, the therapeutic landscape has been enriched by manipulated cellular products (CAR-T, CAR-CIK, CAR-NK). In light of these new perspectives, careful monitoring of minimal-residual disease (MRD) and prompt application of pre-emptive strategies in the post-transplant setting have become imperative. Herein, we review the current state of the art on monitoring, prevention and treatment of relapse of AML after HSCT with particular attention on novel agents and future directions.

Checkpoint Inhibitors and Other Immune-Based Therapies in Acute Myeloid Leukemia.

Immune checkpoint inhibitors have been investigated in acute myeloid leukemia (AML) with an intent to harness the immune microenvironment components to generate an immune response against leukemia. Anti-cytotoxic T-lymphocyte-associated antigen 4 and anti-programmed cell death 1/programmed cell death ligand 1 antibodies have been evaluated in combination with low-intensity therapy and cytotoxic chemotherapy, both in the pretransplant and posttransplant settings. Although the objective response rates with programmed cell death 1- and programmed cell death ligand 1-based therapies have been relatively low, durable stable disease and hematologic improvement were noted in a subset of patients, important endpoints in patients with limited therapeutic options. Novel AML and myelodysplastic syndrome-specific checkpoints such as TIM3 antibodies in combination with azacitidine are showing encouraging efficacy, especially durability of response, in ongoing studies. Anti-CD47/SIRPα therapy in combination with azacitidine has shown encouraging efficacy and safety in frontline AML, especially in TP53-mutated AML, a population of significant unmet need. Other T cell-based immune therapies are under investigation. T-cell and natural killer cell bispecific and trispecific engagers have shown modest activity in patients with relapsed and/or refractory AML albeit with frequent cytokine release syndrome. Chimeric antigen receptor T-cell therapy showed immense success in many lymphoid malignancies and is being evaluated in AML. Future trials should be designed to select patients based on markers of response and tailor therapies according to predictive biomarkers.

De novo and recurrence of metabolic dysfunction-associated fatty liver disease after liver transplantation.

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a new acronym adopted from the consensus of international experts. Given the increasing prevalence of MAFLD in pre-transplant settings, de novo and recurrent graft steatosis/MAFLD are common in post-transplant settings. The impact of graft steatosis on long-term outcomes is unclear. The current knowledge of incidence rate, risk factors, diagnosis, long-term outcomes, and management of graft steatosis (both de novo and recurrent) is discussed in this review.

Treatment of AML Relapse After Allo-HCT

With advances in allogeneic hematopoietic stem cell transplant (allo-HCT), disease relapse has replaced transplant-related mortality as the primary cause of treatment failure for patients with acute myeloid leukemia (AML). The efficacy of allo-HCT in AML is a consequence of a graft-versus-leukemia (GVL) effect that is mediated by T lymphocytes, and unique mechanisms of immune evasion underlying post-allo-HCT AML relapses have recently been characterized. Relapsed AML following allo-HCT presents a particularly vexing clinical challenge because transplant-related toxicities, such as graft-versus-host (GVHD) and infections, increase the risk of treatment-related morbidity and mortality. In general, the prognosis of relapsed AML following allo-HCT is poor with most patients failing to achieve a subsequent remission and 2-year survival consistently <15%. The two factors that have been found to predict a better prognosis are a longer duration of post-transplant remission prior to relapse and a lower disease burden at the time of relapse. When considered in combination with a patient’s age; co-morbidities; and performance status, these factors can help to inform the appropriate therapy for the treatment of post-transplant relapse. This review discusses the options for the treatment of post-transplant AML relapse with a focus on the options to achieve a subsequent remission and consolidation with cellular immunotherapy, such as a second transplant or donor lymphocyte infusion (DLI). While intensive reinduction therapy and less intensive approaches with hypomethylating agents have long represented the two primary options for the initial treatment of post-transplant relapse, molecularly targeted therapies and immunotherapy are emerging as potential alternative options to achieve remission. Herein, we highlight response and survival outcomes achieved specifically in the post-transplant setting using each of these approaches and discuss how some therapies may overcome the immunologic mechanisms that have been implicated in post-transplant relapse. As long-term survival in post-transplant relapse necessarily involves consolidation with cellular immunotherapy, we present data on the efficacy and toxicity of both DLI and second allo-HCT including when such therapies are integrated with reinduction. Finally, we provide our general approach to the treatment of post-transplant relapse, integrating both novel therapies and our improved understanding of the mechanisms underlying post-transplant relapse.

Post-relapse survival in Waldenstrom macroglobulinemia patients experiencing therapy failure following autologous transplantation.

Waldenström macroglobulinemia (WM) is a rare B-cell lymphoproliferative malignancy. Autologous hematopoietic cell transplantation (auto-HCT) is considered in a subset of WM patients with relapsed disease. While registry data has shown a benefit for auto-HCT in relapsed WM, there is a paucity of data on outcomes of patients relapsing after auto-HCT. Eligibility criteria included adult patients with relapsed/refractory WM who underwent auto-HCT between 2007 and 2017. The primary endpoint was post-relapse overall survival (PR-OS). Secondary endpoints were to identify factors prognostic of PR-OS. Of the 48 patients with WM who underwent auto-HCT, 22 (46%) experienced relapse following auto-HCT. Median PR-OS of relapsed WM patients after auto-HCT (n=22) was not reached (NR) (95% confidence interval [CI]: 17.5months-NR). Among patients who relapsed <1year versus ≥1year from auto-HCT, the median PR-OS was 18.4months (95%CI: 0.8-NR) months and NR (95%CI: 17.5-NR), respectively (p=0.06). Of note, disease status at the time of transplant, CR/VGPR versus partial remission did not appear to impact PR-OS. The median PR-OS was significantly longer in patients who received ibrutinib in the post-transplant setting compared to those who did not (NR vs. 18.4 months, 95%CI: 9.1-NR, p=0.02). On univariable analysis, the presence of complex karyotype (RR=4.87, 95% CI=1.22-19.53) and a higher number of prior lines of therapy (RR=1.81, 95% CI=1.23-2.67) were associated with a significantly higher risk of relapse. This is the only study to date that evaluated outcomes of WM patients who relapsed following auto-HCT and provides a benchmark for future trials evaluating survival following auto-HCT relapse.

Pembrolizumab (PEM) Added to ICE Chemotherapy Results in High Complete Metabolic Response Rates in Relapsed/Refractory Classic Hodgkin Lymphoma (cHL): A Multi-Institutional Phase II Trial

Pembrolizumab (PEM) Added to ICE Chemotherapy Results in High Complete Metabolic Response Rates in Relapsed/Refractory Classic Hodgkin Lymphoma (cHL): A Multi-Institutional Phase II Trial

Successful Treatment with ALVR105 for Disseminated Adenovirus Infection in an Infant after Allogeneic Hematopoietic Cell Transplantation: A Case Report

Background: Adenovirus (AdV) disease is one of the most difficult-to-manage complications in infants and children who have received allogeneic hematopoietic cell transplantation (HCT). Cidofovir has been used off-label as preemptive anti-adenoviral therapy. It is the current standard of care treatment, but data supporting its therapeutic value are lacking, and its use is limited by severe renal toxicity.Case: A 10-month-old male with infantile osteopetrosis underwent a single-unit umbilical cord blood transplant (TNC = 21.78 × 10 7/kg, CD34 = 10.5 × 10 5/kg) after myeloablative conditioning (busulfan, cyclophosphamide, and anti-thymocyte globulin). Cyclosporine and mycophenolate mofetil (MMF) were used for graft versus host disease (GVHD) prophylaxis. A positive test for adenovirus from a respiratory viral panel pre-transplant delayed conditioning for six weeks until the patient had two negative tests, one week apart. His post-transplant course was complicated by severe veno-occlusive disease starting on day +3, with secondary respiratory and renal failure. The patient was started on continuous renal replacement therapy along with intravenous defibrotide and high-dose steroids. Neutrophil engraftment did not occur until day +38. Post-engraftment, the patient developed a skin rash diagnosed as GVHD by biopsy, which was treated with corticosteroids at 2 mg/kg/day. As part of viral infection surveillance, the patient received a weekly blood PCR test for adenovirus; on day +25 it was noted he had reactivated adenovirus. He had been demonstrating overall clinical improvement, including declining hepatic transaminases and bilirubin, and reduced respiratory support requirements until day +39, when he developed fever with an increased need for respiratory support and rising transaminases. The respiratory viral panel showed that the patient was positive for adenovirus. Further workup also showed adenovirus PCR positive in stool and increase in quantitative adenoviremia, all consistent with disseminated adenoviral infection. The use of cidofovir was contraindicated in this patient due to renal toxicity.ALVR105 (Viralym-M), an allogeneic, off-the-shelf, multivirus-specific T-cell therapy (VST) that can target AdV, BKV, CMV, EBV, HHV-6, and JCV, was provided by AlloVir on a compassionate-use basis. A cell line that was HLA matched to the patient at 2 out of 8 HLA-A, HLA-B, HLA-DR, and HLA-DQ alleles was identified. After emergency IND approval, institutional review board approval, and family consent, one ALVR105 dose of 0.7 × 10 7 cells was infused on day +48. The dosage was calculated based on the patient's age, weight (8.5 kg), body surface area (0.35 m 2), and the dosing regimen used in a previous phase 2 trial. The patient developed fever and low blood pressure around 30 hours post-infusion, requiring an increase in his existing inotropic support and stress dose hydrocortisone. This was likely associated with underlying post-transplant complications, but a possible association with ALVR105 infusion could not be ruled out.The patient's viral load decreased substantially in the following weeks (Table 1). Concurrently, his liver enzymes, pulmonary secretions, and respiratory support requirements all improved. His respiratory secretions became negative for adenovirus PCR at day +28 post-infusion of ALVR105.At the time of writing, the patient was day +100 post-transplant (day +56 post-infusion of ALVR105), and his veno-occlusive disease had improved. Supplemental oxygen was no longer required, but volume-assured pressure was still in use, likely due to hepatosplenomegaly. The patient had detectable adenovirus viremia but below the threshold of quantitative measurement (<190 copies/ ml). The patient remains well-engrafted with evidence of persistent ALVR105 (Viralym-M) as illustrated in Table-2, but the % of Allovir cells are below our lab's 5% validation threshold. The patient's GVHD has resolved. MMF dosing was stopped on day + 31 from transplant, and the patient is receiving only cyclosporine and physiologic doses of hydrocortisone.Conclusion: In this infant with post allogeneic HCT disseminated adenovirus infection, ALVR105 appeared to be safe and was temporally associated with marked clinical improvement, suggesting VSTs may be of value in very young patients with adenovirus infection. This represents the first use of ALVR105 in an infant (< 1-year-old) patient. [Display omitted] DisclosuresMoon: Allovir: Current Employment, Current equity holder in publicly-traded company. OffLabel Disclosure:Virus specific cell therapy, used against adenovirus infection in post-transplant setting.

Isocitrate Dehydrogenase (IDH) 1 and 2 Mutation Is an Independent Predictor of Better Outcome in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Hematopoietic Stem Cell Transplantation: A Study of the ALWP of EBMT

Isocitrate Dehydrogenase (IDH) 1 and 2 Mutation Is an Independent Predictor of Better Outcome in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Hematopoietic Stem Cell Transplantation: A Study of the ALWP of EBMT

Mitochondrial DNA Mutations Distinguish Individual Donor- and Recipient-Derived Immune Cells Following Matched Unrelated Allogeneic Stem Cell Transplantation

▪Reconstitution of donor hematopoiesis after allogeneic hematopoietic stem cell transplantation (HSCT) forms the basis for effective graft-versus-leukemia responses, but mixed chimerism is not an infrequent outcome. How the donor and host hematopoietic system interact under conditions of mixed chimerism remains incompletely understood. Multi-modal single cell sequencing platforms are increasingly available and provide information regarding cell identities and interactions at high resolution. However, the analysis of post-transplant immune reconstitution requires consistent distinguishing of donor- and recipient-derived cells, which for sparse single cell sequencing data until now has remained a challenge.Recently, mitochondrial DNA (mtDNA) mutations have been recognized for their potential as personal genetic barcodes that can be detected with mitochondrial single cell assay for transposase-accessible chromatin with sequencing (mtscATAC-seq). We hypothesized that individual-specific mtDNA mutations could provide a sensitive and robust approach for distinguishing donor- from recipient-derived cells, and therefore tested this approach on bone marrow (BM) samples from patients with relapsed acute myeloid leukemia (AML) post-HSCT. We employed ATAC with select cell surface antigen profiling by sequencing (ASAP-seq), which enables the detection of mtDNA mutations within distinct surface marker-defined cell populations alongside chromatin accessibility. We selected serial samples collected from the ETCTN 10026 study, which tested combined decitabine (days 1-5, every 4 weeks, start cycle 0) and ipilimumab (day 1, every 4 weeks, start cycle 1) in relapsed AML post-HSCT. We focused on 13 samples (study entry, on treatment and disease progression) from 3 patients: AML1012 (HSCT from a matched related donor [MRD]), and AML1010 and AML1026 (matched unrelated donor [MUD]-HSCT).In total, we obtained 33,943 ASAP-seq profiles, including 3,283 single T cells. While clustering using single cell chromatin profiles alone only allowed identification of either CD4 + or CD8 + T cells, integration with surface marker expression enabled more detailed annotations of 8 T cell subpopulations and NK cells. Further, phenotypically distinct subpopulations such as CD57 + CD4 + and CD8 + T cells shared highly similar chromatin profiles, and 11.1% of CD4 + and 33.7% of CD8 + T cells would have been mislabeled based on clustering of chromatin profiles alone. Thus, ASAP-seq identified T cell subsets with markedly improved accuracy and resolution than scATAC-seq alone.Upon evaluation of mtDNA mutations to discriminate donor- and recipient-derived single T cells, we found that this was unreliable for MRD-HSCT (AML1012), but highly robust in the setting of MUD-HSCT (AML1010, AML1026), consistent with maternal inheritance of mitochondrial genomes. For the latter two patients, we identified 48 donor- and 26 recipient-specific mtDNA mutations, all with high heteroplasmy (range 82 - 99%). Presence of donor- and recipient-derived mtDNA mutations was mutually exclusive, and recipient-specific mtDNA mutations were also detectable in AML cells. Clinical bulk and mtDNA mutation-based single T cell chimerisms were highly correlated (r = 0.97).AML1010 had sustained complete T cell chimerism (>97%) during study treatment. In AML1026, the mtDNA mutation-based T cell chimerism rose from 55% to 71% after 1 cycle of decitabine and then remained stable until disease progression 3 months later. This was associated with increased percentage of donor-derived CD4 + T cells (45% [study entry] vs. 71% [after 1 cycle of decitabine], p < 0.01), while donor-derived CD8 + T cells remained unchanged at 76%. Across all studied timepoints in AML1026, donor versus recipient skewing was also highest in CD4 + T cell subsets, with fewer naïve (20% vs. 31%, p < 0.01) but more donor-derived CD57 + CD4 + T cells (13% vs. 3%, p < 0.01).We demonstrate that mtDNA mutations can discriminate between donor- and recipient-derived single cells, enabling detection and in-depth characterization of chimeric immune cell dynamics after MUD HSCT. This approach will allow to systematically dissect conditions of mixed chimerism in the post-transplant setting with larger studies. DisclosuresDeAngelo: Abbvie: Research Funding; Takeda: Consultancy; Servier: Consultancy; Pfizer: Consultancy; Novartis: Consultancy, Research Funding; Jazz: Consultancy; Incyte: Consultancy; Forty-Seven: Consultancy; Autolus: Consultancy; Amgen: Consultancy; Agios: Consultancy; Blueprint: Research Funding; Glycomimetrics: Research Funding. Neuberg: Madrigal Pharmaceuticals: Other: Stock ownership; Pharmacyclics: Research Funding. Sankaran: Cellarity: Consultancy; Forma: Consultancy; Novartis: Consultancy; Branch Biosciences: Consultancy; Ensoma: Consultancy. Soiffer: Jasper: Consultancy; Jazz Pharmaceuticals, USA: Consultancy; Precision Biosciences, USA: Consultancy; Juno Therapeutics, USA: Other: Data Safety Monitoring Board; Kiadis, Netherlands: Membership on an entity's Board of Directors or advisory committees; Rheos Therapeutics, USA: Consultancy; Gilead, USA: Other: Career Development Award Committee; NMPD - Be the Match, USA: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy. Garcia: Genentech: Research Funding; Prelude: Research Funding; Pfizer: Research Funding; AstraZeneca: Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Wu: Pharmacyclics: Research Funding; BioNTech: Current equity holder in publicly-traded company. OffLabel Disclosure:ipilimumab to modulate anti-leukemia immunity in the post-transplant and transplant-naive context

Efficacy and Safety of Cyclosporine Treatment in Autoimmune Cytopenias: The Experience of Two Italian Reference Centers

▪Background: Autoimmune cytopenias (immune thrombocytopenia ITP, autoimmune hemolytic anemia AIHA, and chronic idiopathic neutropenia CIN) are a heterogeneous group of disorders characterized by the presence of autoantibodies directed against platelets (PLT), erythrocytes, and neutrophils (ANC). Frontline steroids are the mainstay of treatment, although most patients relapse and require 2 nd line therapies which slightly differ according to disease subtype. Rituximab is mainly effective in AIHA, although only a fraction of cases would experience long-term relapse-free. Splenectomy may be contraindicated due to age and risk of thrombotic and infectious complications and thrombopoietin-receptor agonists (TPO-RA), effective in more than 70% of ITP patients, may result in great PLT fluctuations and increased bone marrow reticulin fibrosis.Cyclosporine (CyA) is an immunosuppressant used for over 30 years in the post-transplant setting and in the treatment of aplastic anemia. It is a manageable oral drug with known toxicities and its plasma concentrations may be monitored to optimize treatment. However, few data exist about its efficacy in autoimmune cytopenias either used as single drug or in combination with other treatments.Aim: The aim of this study was to evaluate the efficacy and safety of CyA in a cohort of patients with ITP, AIHA, and CIN, followed at two reference hematology centers in Milan, Italy.Methods: Medical charts of consecutive patients treated with CyA 3-5 mg/ kg day in the last 20 years were evaluated. Responses were assessed at 3, 6 and 12 months, and divided into partial (PR, for Hb> 10 g/dL; PLT> 30x 109/L and ANC> 0.8 x 109/L) and complete (CR, for Hb> 12 g/dL; PLT> 100x109/L; ANC>1 x 109/L). Adverse events were recorded according to CTCAE criteria.Results: 41 patients, 27 ITP (66%), 11 AIHA (27%) and 3 CIN (7%), were included, 16 men (39%) and 25 women (61%), with a median age of 60 year (21-81). The median time from diagnosis to CyA start was of 10 years (5-15), with a median of 3 (1-8) previous therapy lines. Most patients were receiving concomitant treatment including steroids (N=13), IVIG (3), or TPO-RA (14). Reasons to start CyA included no response to previous treatments (N=27), platelets fluctuations (N=5) or bone marrow fibrosis (N=5) on TPO-RA, and contraindication for splenectomy (N=4). Median duration of CyA therapy was 5 years (1-9) and 34 patients (83%) responded: 34% CR, 44% PR at month+3; 39% CR and 39% PR at month+6; and 26%CR and 43%PR at month+12 (Figure 1). Specifically, median PLTs increased by 32 x10^9/L at month+3, by 121 x10^9/L at month+6, and by 43 x10^9/L at month+12. Median Hb improved by 0.5 g/dL at month+3, by 1 g/dL at month+6, and by 2,6 g/dL at month +12. Median ANC augmented by 0.7 x10^9/L at month +3, by 1.7 x10^9/L at month +6, and by 0.07 x10^9/L at month +12. Importantly, 9 patients could stop steroids, and 10 subjects discontinued or tapered TPO-RA (5 each). Better responses were observed in ITP patients with baseline bone marrow hypocellularity (p = 0.01), absence of reticulin fibrosis (p=0.02), and in those not previously splenectomized (p=0.04). Among AIHA cases, those with IgG+C direct antiglobulin test positivity showed higher percentage of non-response (67 versus 22% in IgG+). Adverse events were mainly G1-2, occurring in 52% of patients, and included asthenia, dyspnea, myalgia, nausea, vomiting, diarrhea and abdominal pain, epistaxis, petechiae and an Escherichia Coli cystitis. Three patients on concomitant long-term steroids developed a G3 event (1 pulmonary embolism, 1 Aspergillus lung infection and 1 bronchitis), and 1 died for Pneumocystis jirovecii pneumonia.Conclusion: Cyclosporine was effective in about 80% of highly pretreated patients and allowed tapering/discontinuation of concomitant treatments in 63% of cases. Responses were higher in those with ITP, and hypocellular bone marrow without reticulin fibrosis. The occurrence of infectious episodes, including a fatal pneumonia, warrants careful surveillance in this heavily pretreated patient population. [Display omitted] DisclosuresFattizzo: Kira: Speakers Bureau; Alexion: Speakers Bureau; Novartis: Speakers Bureau; Momenta: Honoraria, Speakers Bureau; Annexon: Consultancy; Apellis: Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Bianchi: Agios pharmaceutics: Consultancy, Membership on an entity's Board of Directors or advisory committees. Barcellini: Agios: Honoraria, Research Funding; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Alexion Pharmaceuticals: Honoraria.

Phase II Trial of Eprenetapopt (APR-246) in Combination with Azacitidine (AZA) As Maintenance Therapy for TP53 Mutated AML or MDS Following Allogeneic Stem Cell Transplantation (SCT)

Phase II Trial of Eprenetapopt (APR-246) in Combination with Azacitidine (AZA) As Maintenance Therapy for TP53 Mutated AML or MDS Following Allogeneic Stem Cell Transplantation (SCT)

Effect of the Neddylation Inhibitor Pevonedistat on Normal Hematopoietic Stem Cell Subsets and Immune Cell Composition

Introduction: Antitumor activity of the neddylation inhibitor pevonedistat has been documented in several hematologic and non-hematologic malignancies. Unexpectedly, Zhou et al (PNAS, 2016) discovered a dose-dependent biphasic effect of pevonedistat in solid tumor cell lines. While micromolar concentrations inhibited tumor cell growth, low nanomolar concentrations significantly increased cell proliferation and tumor stem cell self-renewal both in vitro and in vivo. The effect of low-dose pevonedistat has not yet been explored in the field of hematopoietic stem cell transplantation. Therefore, we evaluated how pevonedistat affects the viabiilty, growth and proportions of CD34 + cell subpopulations. In view of the emerging role of neddylation in the regulation of both innate and adaptive immunity, we also investigated the influence of pevonedistat on T-cell activation to explore a potentially beneficial effect on posttransplant immune complications.Methods and Results: Using the WST-1 assay we confirmed the biphasic effect of pevonedistat on normal mobilized CD34 + cells. Incubation for 72 h with 0.1 µM pevonedistat significantly increased metabolic activity as a surrogate parameter for proliferation, while 1.0 µM pevonedistat showed a cytotoxic effect. We explored the underlying mechanism for the low-dose effect. Since Zhou et al. previously showed that pevonedistat can promote tumor stem cell proliferation by inducing EGFR homodimerization, we used a proximity ligation assay and found that 0.1 µM pevonedistat induced EGFR homodimerization in normal mobilized CD34 + cells, too. In addition to homodimerization, we also looked at phosphorylation at Tyr1068, a marker of EGFR activation. By flow cytometry, we showed that phosphorylation was increased by 0.01 µM and 0.1 µM pevonedistat. Using an ELISA-based transcription assay, we also observed a biphasic effect of pevonedistat on c-Myc expression, which is regarded as a marker of ‘stemness’. Incubation with pevonedistat for 72 hrs at 0.01 and 0.1 µM stimulated expression of c-Myc, whereas incubation at 1.0 µM downregulated c-Myc.Fractions of hematopoietic stem and progenitor cell (HSPC) subpopulations were measured in CD34 + cells from cord blood after incubation with 0.01, 0.1 and 1.0 µM pevonedistat. Flow cytometry was performed using antibodies against CD34, CD45RA and CD133, as well as 7-AAD for testing cell viability. Exposure to pevonedistat for 72 hrs at 0.1 µM caused an increase in the number of CD34 + cells compared to vehicle-treated CD34+ cells at 72 h as well as compared to initial number of CD34+ cells, whereas 1.0 µM caused a significant decrease. The absolute number of multipotent progenitors (MPP) (CD34 +CD133 +CD45RA -) remained relatively stable at all concentrations, while lympho-myeloid progenitors (LMPP) (CD34+CD133+CD45RA+) and late progenitors (LP) (CD34+CD133-CD45RA+) increased slightly with 0.1 µM pevonedistat compared with controls. However, a significant decrease in LMPP and LP cell numbers was observed at 1.0 µM.Different concentrations of pevonedistat were tested for their capability to modulate allogeneically stimulated T cell activation in a multi-donor mixed lymphocyte reaction (mdMLR) assay in vitro. Mesenchymal stromal cells (MSCs)-derived extracellular vesicles (MSC-EV) were used as internal immuno-modulatory and non-immuno-modulatory controls in the assay. After 5 days, alterations in the immune cell composition were analyzed by flow cytometry. Pevonedistat was not toxic for MNCs in the mdMLR. However, it decreased the number of activated (CD25high CD54+) CD4+ cells and CD8+ cells.Conclusions: One of the problems in the post-transplant period is a rapid decline in MPP numbers, associated with increased risk of engraftment failure. We showed that low-dose pevonedistat (0.1 µM) is capable of increasing the number of CD34 + cells in vitro while keeping the absolute number of MPPs stable. This finding, together with the observed increase in c-Myc expression, suggests that pevonedistat may help to preserve ‘stemness’ of CD34+ donor cells, thus supporting engraftment of hematopoietic stem and progenitor cells. Furthermore, the immunosuppressive effects revealed by mdMLR suggest that low-dose pevonedistat may also play a useful immunomodulatory role in the post-transplant setting to potentially reduce the risk of graft-versus-host disease. [Display omitted] DisclosuresMajidi: Takeda: Research Funding. Germing: Jazz Pharmaceuticals: Honoraria; Bristol-Myers Squibb: Honoraria, Other: advisory activity, Research Funding; Celgene: Honoraria; Novartis: Honoraria, Research Funding; Janssen: Honoraria. Zeiser: Incyte, Mallinckrodt, Novartis: Honoraria, Speakers Bureau. Gattermann: Celgene: Honoraria; Takeda: Research Funding; Novartis: Honoraria.

Rescue liver re-transplantation after graft loss due to severe rejection in the setting of pre-transplant nivolumab therapy

Immune checkpoint inhibitors (ICI) have been used to treat hepatocellular carcinoma (HCC) since 2017. The safety of ICIs in the setting of solid organ transplantation remains controversial. When used in the post-transplant setting, ICIs have been associated with high allograft rejection rates, but there are few published reports on the use of ICIs prior to transplant. We present the first reported case of rescue liver re-transplantation after loss of the first allograft due to severe acute rejection with extensive hepatic necrosis in the setting of pre-transplant ICI therapy with the PD-1 inhibitor nivolumab. It is likely that the durable immune response triggered by nivolumab contributes to graft rejection, therefore extreme caution should be taken when using ICIs before transplant until further investigation has been conducted on their safety in the pre-transplant setting.