Equine Antithymocyte Globulin Research Articles

Efficacy and safety of avatrombopag in combination with immunosuppressive therapy in treatment-naïve and relapsed/refractory severe aplastic anaemia: protocol for the DIAAMOND-Ava-FIRST and DIAAMOND-Ava-NEXT Bayesian Optimal Phase II trials

IntroductionImmunosuppressive therapy (IST) with antithymocyte globulin (ATG) and ciclosporin is standard of care for patients with severe aplastic anaemia (sAA) not eligible or suitable for allogeneic stem cell transplant. While...

Autologous Stem Cell Transplantation with Intensity Modulated Total Body Irradiation Conditioning for Systemic Sclerosis

Based on the seminal SCOT trial, autologous stem cell transplantation (HSCT) using myeloablative total body irradiation (TBI) and anti-thymocyte globulin (ATG) as a conditioning regimen has become a standard treatment option for certain patients with systemic sclerosis (SSc). In patients with SSc, normal organs are more radiosensitive and prone to compromised function, and therefore lungs and kidneys require dose reduction. With traditional techniques, TBI requires heavy and thick physical blocks, which can be cumbersome and have poor reproducibility. We hypothesized that intensity modulated radiation therapy (IMRT) TBI compared to standard anteroposterior (AP)/posteroanterior (PA) TBI would facilitate improvements in dosimetry and reproducibility (due to not requiring physical blocks) without compromising outcomes. Herein, we report a single-institution retrospective analysis of patients with SSc treated with an IMRT TBI. Patients with SSc who underwent HSCT with TBI between 2017 and 2022 were eligible. All patients underwent conditioning with equine ATG, cyclophosphamide 120 mg/kg, and IMRT TBI administered twice-daily to a total dose of 800 cGy in 200 cGy fractions. A minimum of 80% of the PTV was to receive prescription dose. Mean lung and kidney dose were to be less than 200 cGy. Patients were then replanned using an AP/PA technique for dosimetric comparison. The primary endpoint was planning target volume (PTV), lung, and kidney dosimetry. Secondary endpoints included event-free survival (EFS), overall survival (OS), disease-modifying antirheumatic drug-free survival (DMARD-FS), treatment related mortality (TRM), and toxicity. A total of 14 patients were eligible for our analysis. On dosimetric analysis, the mean dose to the PTV was significantly higher on the IMRT compared to the AP/PA plans (809.4 cGy versus 728.5 cGy, p<0.001). The mean dose to the lungs (239.5 cGy versus 443.9 cGy, p<0.001) and kidneys (204.9 cGy versus 281.2 cGy, p<0.001) was significantly lower. Median follow-up was 34.6 months (1.0-51.7 months). There was one case of TRM secondary to respiratory failure. The 24-month OS, EFS, and DMARD-FS estimates were 92.9%, 74.3%, and 70.0%, respectively. Three patients experienced adverse events, which included respiratory failure (n = 1), renal failure (n = 1), and death (n = 1). No patients experienced clinically significant pneumonitis or nephritis that were deemed to be a likely consequence of TBI. Five patients subsequently initiated DMARDs, but three did so due to worsening skin symptoms without other major organ dysfunction. Use of IMRT TBI as part of the conditioning regimen for HSCT for SSc yields improved dosimetry relative to a standard AP/PA technique, with efficacy and toxicity outcomes comparable with published data. This technique should be considered for patients undergoing HSCT for SSc and warrants inclusion in prospective trials for SSc that involve TBI.

Active Clinical Trials in Hepatic Encephalopathy: Something Old, Something New and Something Borrowed.

Hepatic encephalopathy (HE) is a potentially reversible neurocognitive syndrome that occurs in patients with acute or chronic liver disease. Currently, most of the therapies for HE aim to reduce ammonia production or increase its elimination. To date, only two agents have been approved as treatments for HE: lactulose and rifaximin. Many other drugs have also been used, but data to support their use are limited, preliminary or lacking. The aim of this review is to provide an overview and discussion of the current development of treatments for HE. Data from ongoing clinical trials in HE were obtained from the ClinicalTrials.gov website, and a breakdown analysis of studies that were active on August 19th, 2022, was performed. Seventeen registered and ongoing clinical trials for therapeutics targeting HE were identified. More than 75% of these agents are in phase II (41.2%) or in phase III (34.7%). Among them, there are many old acquaintances in the field, such as lactulose and rifaximin, some new entries such as fecal microbiota transplantation and equine anti-thymocyte globulin, an immunosuppressive agent, but also some therapies borrowed from other conditions, such as rifamycin SV MMX and nitazoxanide, two antimicrobial agents FDA approved for the treatment of some types of diarrheas or VE303 and RBX7455, two microbiome restoration therapies, currently used as treatment of high-risk Clostridioides difficile infections. If working, some of these drugs could soon be used as valid alternatives to current therapies when ineffective or be approved as novel therapeutic approaches to improve the quality of life of HE patients.

Autologous Stem Cell Transplantation With Intensity Modulated Total Body Irradiation Conditioning for Systemic Sclerosis

Autologous stem cell transplantation (HSCT) using myeloablative total body irradiation (TBI) and anti-thymocyte globulin (ATG) as a conditioning regimen has become a standard treatment option for certain patients with systemic sclerosis (SSc). Normal organs are more radiosensitive and prone to compromised function in SSc, and therefore lungs and kidneys require dose reduction. We evaluated the role of intensity modulated radiation therapy (IMRT) TBI compared to standard anteroposterior (AP)/posteroanterior (PA) TBI technique. Patients with SSc who underwent HSCT with TBI between 2017 and 2022 were eligible. All patients underwent conditioning with equine ATG, cyclophosphamide 120 mg/kg, and IMRT TBI to a total dose of 800 cGy in 200 cGy fractions. Patients were replanned using an AP/PA technique for dosimetric comparison. Patients were evaluated for outcomes including event-free survival (EFS), overall survival (OS), disease-modifying antirheumatic drug-free survival (DMARD-FS), and treatment related mortality (TRM). 14 patients were eligible for our analysis. Median follow-up was 34.6 months (1.0-51.7 months). There was one case of TRM secondary to respiratory failure. The 24-month OS, EFS, and DMARD-FS estimates were 92.9%, 74.3%, and 70.0%, respectively. Three patients experienced adverse events, which included respiratory failure (n=1), renal failure (n=1), and death (n=1). Five patients subsequently initiated DMARDs, but three did so due to worsening skin symptoms without other major organ dysfunction. On dosimetric analysis, the mean dose to the planning target volume (PTV) was significantly higher on the IMRT compared to the AP/PA plans (809.4 cGy versus 728.5 cGy, p<0.001). The mean dose to the lungs (239.5 cGy versus 443.9 cGy, p<0.001) and kidneys (204.9cGy versus 281.2 cGy, p<0.001) was significantly lower. Use of IMRT TBI as part of the conditioning regimen for HSCT for SSc yields improved dosimetry with efficacy and toxicity outcomes comparable with published data.

Equine antithymocyte globulin for treatment of acute T-cell mediated rejection

Equine antithymocyte globulin for treatment of acute T-cell mediated rejection

Comparable Long-Term Outcomes of Low-Dose Versus Standard-Dose Equine Anti-Thymocyte Globulin with Cyclosporine in Aplastic Anemia

Background: Immunosuppressant therapy (IST) with equine anti-thymocyte globulin (eATG) and cyclosporine is the current standard treatment for transplant-ineligible aplastic anemia (AA) patients. Recently eltrombopag has been added to this IST backbone. The standard dose of eATG is 40mg/kg/day, however, the ideal dose of eATG is not known. We studied the efficacy of 25 mg/kg/day x 4 days (low-dose) with standard-dose eATG in transplant-ineligible AA patients at our tertiary care centre. Methods: AA patients (age >12 years) who received eATG and cyclosporine from 2003 to 2021 were retrospectively analysed.The choice of eATG dose was based on patients'finances. Patients developing nephrotoxicity with cyclosporine were switched to oral mycophenolate mofetil. Overall response rates (ORR) [complete response (CR) and partial response (PR)] were analysed at 3 months, 6 months and 12 months after eATG.Kaplan-Meier survival analyses were performed to analyse overall survival (OS) and event free survival (EFS). Results: Ninety-three AA patients received eATG during the study period. Their median age was 30 years (range 13-65 years); 60 (64.5%) were males. PNH clone was present in 33 (35.5%) patients. Median duration from symptom onset to diagnosis was 3 months (range 1-100 months). 62 patients (66.7%) received low-dose eATG; 31 patients (33.3%) received standard-dose eATG. 17 patients (18.3%) received eltrombopag in addition to eATG plus cyclosporine. The number of patients eligible for response assessment at 3 months, 6 months and 12 months were 93 (100%), 86 (92.4%) and 80 (86%), respectively. ORRs in the total study population at 3 months, 6 months, and 12 months were 49.5%, 66.3%, and 72.5%, respectively; respective CR rates were 5.4%, 14% and 20%. The differences between ORRs among low-dose versus standard-dose eATG groups at 3 months (50% vs 48.4%; p = 0.88), 6 months (63.8% vs 71.4%; p = 0.67) and 12 months (69.6% vs 79.2%; p = 0.167) were statistically insignificant. Median duration of oral cyclosporine after eATG was 25 months (range 3-144 months); 23 patients (24.7%) who were having suboptimal response at 6 months (PR 15, NR 8) and 12 months (PR 18, NR 5) achieved CR after 12 months with the continuation of cyclosporine. The median duration of follow up was 52 months (range 3-229 months). 11 patients (11.8%) relapsed after eATG (7 in low-dose group, 4 in standard-dose group) after a median duration of 32 months (range 12-84 months). Two patients (2.1%) underwent clonal evolution to AML and MDS-EB2 at 83 months and 35 months, respectively (both in standard-dose group). 15 patients (16.1%) died during follow up and 18 (19.3%) were lost to follow up. 10-year OS and 10-year EFS of the total study population were 80% and 64%, respectively. There was no significant difference between low-dose and standard-dose groups in terms of 10-year OS (82.4% vs 74.8%; p = 0.43) and 10-year EFS (64.5% vs 63.1%; p = 0.64), respectively. Conclusion: This study revealed that low-dose eATG and standard dose eATG have comparable response rates and long-term survival. CR rates continue to improve with continuation of oral cyclosporine beyond 12 months in patients who have partial or no response at 6 and 12 months. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Autologous Stem Cell Transplantation (ASCT) for Refractory Juvenile-Onset Systemic Sclerosis (jSSc) Is Safe and Well Tolerated and Improves Clinical and Patient-Reported Outcomes

Introduction: jSSc is a rare autoimmune disease that leads to inflammation, fibrosis, and dysfunction of multiple organ systems which can cause skin sclerosis, interstitial lung disease (ILD), myositis, fasciitis, gastrointestinal and vascular disease. Severe SSc is often refractory to immunomodulatory medications including newer targeted agents. ASCT has demonstrated success in adults with SSc, but experience and data in pediatric patients is limited. Methods: We report our first four consecutive adolescent and young adult ASCT patients. All patients were referred to our scleroderma center at UPMC Children's Hospital of Pittsburgh where they were evaluated by our multidisciplinary team. Baseline patient characteristics are summarized in Table 1. Patients met criteria for ASCT by severity of lung or skin disease, or both. The first 3 patients had severe ILD or musculoskeletal chest wall weakness resulting in pulmonary function tests (PFTs) below traditional cut offs for adult SSc ASCT trials. All four patients had refractory disease and had previously received 3-8 immunomodulatory medications. Autologous stem cells were mobilized with cyclophosphamide and filgrastim and collected via pheresis. Following this, conditioning chemoradiation was administered per an IRB-approved individual treatment plan (Patients 1-3) or on our clinical trial NCT03630211 (Patient 4) with rituximab, anti-thymocyte globulin (ATG), TBI 600 cGy with lung and kidney shielding, and cyclophosphamide or thiotepa +/- alemtuzumab. A CD34+ selected cryopreserved autologous peripheral blood stem cell graft was infused on day 0. Antimicrobial prophylaxis was given per institutional standard and PCRs for EBV, CMV and adenovirus were closely monitored. Steroids were weaned off by 5 weeks post-ASCT. Results: The median cell dose was 5.9 e6 CD34/kg. All patients engrafted, with median neutrophil engraftment on day 11 (range 11-15), and median platelet engraftment (>50K) on day 18.5 (range 16-20). There were infusion-related side effects with equine ATG, but none with rabbit ATG. There were no cases of sinusoidal obstructive syndrome, thrombotic microangiopathy or clinically significant bleeding. No patients required a PCA for pain and received minimal (median=3) doses of narcotics. Patients were discharged from the hospital a median of 19 days after transplant (range 17-21). Only one patient was readmitted, and had a negative 48 hour infectious rule out. Two patients acquired COVID-19 infections at 5 and 19.5 months post-ASCT; both remained outpatient with quick improvement after treatment with best available therapy. There were no viral reactivations, bacterial or fungal infections. There has been no evidence of organ toxicity and there are objective improvements in clinical parameters as well as patient reported outcomes (PROs) over the follow-up visits (Table 2). All patients demonstrated an improvement in their skin involvement, as measured by the modified Rodnan Skin Score (mRSS). There was an improvement in clinical symptoms and exam findings of Raynaud's. The lower esophageal sphincter became less hypotensive; objective measures and symptoms of gastroesophageal reflux were much improved. Despite severely reduced values of forced vital capacity (FVC) and diffusing capacity of the lungs for carbon monoxide (DLCO) prior to ASCT, all subjects regained pre-ASCT values. All patients demonstrated an improvement in their PROs and report improvement in fatigue, pain, and the ability to participate in activities of daily living. All patients are off immunomodulatory medications. Tandem serial skin biopsies of the forearm support decreased collagen burden and disappearance of a myofibroblasts population with single cell RNA sequencing (n=3, timepoints 0, 6, 12 mos; data not shown), which correlates with an improvement in the skin score. Conclusions: In refractory jSSc patients, ASCT is well tolerated, even in patients with severe disease who would otherwise not be eligible for clinical trials based on exclusion criteria that were developed for adults with SSc. ASCT can serve as a hard reset to the immune system for patients with this refractory autoimmune disease, with improvements in clinical parameters that reflect disease modification involving the skin, musculoskeletal, vascular, and gastrointestinal systems. Further clinical research treating patients with this rare disease is of great need. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Efficacy and Safety of Avatrombopag in Combination with Immunosuppressive Therapy in Treatment-Naïve and Relapsed/Refractory Severe Aplastic Anaemia - the Diaamond-Ava-First and Diaamond-Ava-Next Bayesian Optimal Phase II Trials

Background: Improving treatment for patients with severe aplastic anemia (sAA) is a priority. Immunosuppressive therapy (IST) with antithymocyte globulin (ATG) and ciclosporin is standard of care for patients with sAA not eligible or suitable for allogeneic stem cell transplant. While 50-75% of patients respond to IST, few achieve complete responses and a significant proportion are refractory or relapse. The addition of eltrombopag, a thrombopoietin-receptor agonist (TPO-A), to IST has been shown to improve hematological responses in sAA. Avatrombopag is a second-generation TPO-A, and like eltrombopag, lacks competitive binding with endogenous TPO, suggesting it may also be effective in AA. Avatrombopag has potential advantages over eltrombopag, including dosing, toxicity profile and pharmacokinetics. It has also been shown to have greater in vitro and in vivo pharmacological potency than eltrombopag. However, to date avatrombopag has not been studied in sAA. Methods: The DIAAMOND Ava-FIRST and DIAAMOND Ava-NEXT trials are investigator-initiated, non-randomised, single-arm registry-based Bayesian Optimal Phase II (BOP2) trials. The FIRST trial is evaluating avatrombopag in addition to IST in patients with untreated sAA. Patients receive IST (equine ATG and ciclosporin) plus avatrombopag from day 1 until day 180 at 60 mg oral daily and dose adjusted according to platelet count. Two primary endpoints, complete response (CR) rate and acquired clonal evolution (ACE) at 6 months are monitored at each interim analysis where a go/no-go decision is made by evaluating the posterior probability of the events of interest. The maximum sample size is 50 evaluable patients. The stopping boundaries were calculated with a target false positive rate of 10% under the global null as recommended in phase II studies. The performance of the trial and operating characteristics were assessed with 10,000 simulations. Other trial endpoints which are collected until 24 months following enrolment include rate and time to first hematological response, survival, cytogenetic evolution, progression to hematological malignancy, safety and quality of life. Exploratory assessments of interest include changes in iron studies and marrow iron stores, longitudinal cell free DNA somatic mutation analysis and T-cell receptor repertoire studies. In the NEXT trial, patients with relapsed or refractory sAA, six or more months following at least one course of horse or rabbit ATG are eligible. All patients receive avatrombopag at 60 mg oral daily from day 1 until day 180, further additional IST is at the discretion of the treating clinician. Two primary endpoints, hematological response (HR) rate and ACE are monitored at each interim analysis following which a go/no-go decision is made as described in the FIRST trial. The trials are embedded within the Australian Aplastic Anaemia and Other Bone Marrow Failure Syndromes Registry, which will allow long-term follow-up of participants after completion of the trial (at 24 months). Progress: The FIRST trial has enrolled 40 patients and the NEXT trial 16 patients. The dosing of avatrombopag was changed after the initial eleven patients were enrolled, when the starting dose was 20 mg daily and increased to a maximum of 60 mg daily over 8 weeks based on hematological response. This change was made based on observed tolerability of the maximum (60 mg) dose and timing of response rates. Interim analyses have been performed for both trials and stopping boundaries for efficacy or safety have not been met.

93 - Distally-Timed Equine Antithymocyte Globulin (eATG) in Allogeneic Hematopoietic Cell Transplantation (HCT) Conditioning – Pharmacokinetics and the Relationship between Total E-ATG Levels, Pre-HCT Absolute Lymphocyte Count, Immune Reconstitution, and Graft-Versus-Host Responses

93 - Distally-Timed Equine Antithymocyte Globulin (eATG) in Allogeneic Hematopoietic Cell Transplantation (HCT) Conditioning – Pharmacokinetics and the Relationship between Total E-ATG Levels, Pre-HCT Absolute Lymphocyte Count, Immune Reconstitution, and Graft-Versus-Host Responses

Sars-Cov-2 Infection Associated with Aplastic Anemia and Pure Red Cell Aplasia

Introduction: Aplastic anemia (AA) is a life-threatening disorder characterized by pancytopenia and a hypocellular bone marrow. Pure red cell aplasia (PRCA) is a similar disorder with primary reduction in the red blood cell population and virtual absence of erythroid precursors in the bone marrow. While the etiology of immune mediated marrow failure is multifactorial, preceding viral infections have been associated with the disease; these include parvovirus B19, cytomegalovirus, and Epstein-Barr virus. We present four cases of immune mediated marrow failure with either preceding or simultaneous SARS-CoV-2 infection.Methods: The medical records of patients treated for AA or PRCA at the University of Texas Southwestern Medical Center, Parkland Hospital, and the National Institutes of Health (NIH) were reviewed for SARS-CoV-2 infection. Four patients without prior hematological diseases were identified who had SARS-CoV-2 infection prior to or with simultaneous the diagnosis of AA or PRCA.Results: Patient #1 was a 22-year-old white female who was diagnosed with asymptomatic COVID-19 10 days prior to her pancytopenia and AA diagnosis was confirmed by bone marrow biopsy (5% cellularity; Table 1). Her extensive work-up including HIV, hepatitis panel, immunoglobulins, B12 and folate was negative, and she underwent HLA-matched family donor hematopoietic stem cell transplant. Patient #2 was a 69-year-old Asian female who presented to her primary care physician with symptoms of fatigue and was found to be pancytopenic. CBC from a few months prior was completely normal. Further work-up was positive for COVID-19 and negative for HIV, nutritional deficiency, or hemolysis. She did not have respiratory symptoms, was eventually diagnosed with pRBC and platelet transfusion-dependent severe AA (5-10% cellularity on bone marrow), and underwent treatment with cyclosporine, equine antithymocyte globulin, and eltrombopag. She has had a partial response to this therapy. Both patients had bone marrow specimens stained for SARS-CoV-2 by immunohistochemistry that were negative. Patient #3 was a 76-year-old white male who was diagnosed with COVID-19 4 months prior to presenting with a non-ST segment myocardial infarction and found to be profoundly anemic, requiring pRBC transfusion. He re-presented with chest pain one week later and was found to be anemic again, and required transfusion. A trial of darbepoetin alfa was unsuccessful. Extensive work-up for malignancy, infection, and autoimmune etiologies were negative. He was diagnosed with PRCA based on the bone marrow biopsy and initiated treatment with cyclosporine. Patient # 4 was diagnosed with severe AA (presenting as pancytopenia) and COVID-19 infection. He had fatigue for one month and fever, chills and sore throat one-week prior seeking medical care. Testing for hepatitis, HIV, EBV, and CMV was negative. He was treated on a clinical trial (NCT04304820) at NIH with cyclosporine and eltrombopag until SARS-CoV-2 PCR was negative then received equine anti-thymocyte globulin. He has achieved a complete hematologic response at 6 months and remains well at last follow-up.Conclusion: The four patients described had minimal respiratory COVID-19 symptoms, but they presented with cytopenia and were eventually diagnosed with bone marrow failure. It is possible that this is co-incidental due to the high prevalence of SARS-CoV-2. However, there is emerging evidence that COVID-19 pneumonia is a hyperinflammatory and immune dysregulated state improved by dexamethasone therapy. Other immune mediated hematologic conditions, such as autoimmune hemolytic anemia and immune thrombocytopenia, have been reported. The onset from infection to cytopenia appears rapid, although patients often presented with symptoms for many days prior to diagnosis and thus testing may have been delayed from the onset of infection. This case series does not provide a mechanistic link between SARS-CoV-2 infection and bone marrow failure, but it raises the possibility that SARS-CoV-2 may mediate an immunologic response that contributes to marrow failure. Patients appear to respond well to standard immunosuppressive treatment. Further cases and studies are needed to determine if this is directly linked to SARS-CoV-2 and whether the natural history and response to standard therapy is different than idiopathic cases. [Display omitted] DisclosuresYoung: Novartis: Research Funding.

Efficacy of Low Dose Generic Antithymocyte Globulin and Cyclosporine in Idiopathic Aplastic Anemia

Background: In transplant ineligible idiopathic aplastic anemia (IAA) patients, immunosuppressant therapy (IST) with equine Anti-thymocyte globulin (eATG) and cyclosporine is a standard treatment option. In resource constraint settings, where cost is an indisputable determinant of care, haematologists perennially face challenges to come forward with economical yet effective treatment strategies to ensure wider affordability. To explore cost-effective therapeutic options for this under addressed patient population, we studied the efficacy of a lower dose of generic eATG.Methods: Transplant ineligible AA patients (age > 12 years) treated with generic eATG (Thymogam) and cyclosporine from January 2010 to December 2016 were retrospectively analysed. Efficacy of low dose generic eATG (25 mg/kg/d for 4 days) was analysed and compared with standard dose of generic eATG (40 mg/kg/d for 4 days). The choice of eATG dose was based on affordability of the patient. The patients who had completed eATG therapy and followed up at 3 months and 6 months were included in efficacy analysis. Overall response rate (ORR) [including complete response (CR) and partial response (PR)] at 3 months and 6 months were analysed.Results: Thirty-four AA patients treated with generic eATG and cyclosporine were analysed. Mean age was 23.74 years (range 13-45 years); 22 (64.7%) were males. PNH clone was present in 13 (38.2%) patients. Median duration of follow up was 21.1 months (range 3-42 months). Out of 34 patients included in the study, one patient died on day 15 of therapy due to febrile neutropenia, 32 followed up at 3 months and 30 completed 6 months follow up. ORR in the study population was 48.8% at 3 months and 60.6% at 6 months. Difference between ORR at 3 months with low dose (42.9%, CR 0, PR 6) and standard dose eATG (47.3%, CR 0, PR 9) was not significantly significant (p = 0.8). Similarly, difference in ORR at 6 months was not statistically significant between low dose (53.8%, CR 0, PR 7) and standard dose (61.1%, CR 1, PR 10) eATG (p = 0.537). Serious adverse events were observed in three patients in low dose group [non-fatal febrile neutropenia 1; seizure 1; acute kidney injury (AKI) 1] and 7 patients in standard dose group [death due to febrile neutropenia 1; non-fatal febrile neutropenia 2; intracranial bleed 1; AKI 2; flash pulmonary edema 1]. On multivariate analysis for ORR at 6 months, none of the expected variables (age, absolute neutrophil count, absolute lymphocyte count, interval between onset of symptoms to initiation of therapy) could reach statistical significance. Two patients relapsed (after 30 months and 36 months, respectively) after receiving low dose ATG and three patients relapsed after receiving standard dose ATG (after 18 months, 26 months and 38 months, respectively).Conclusion: We found that efficacy of low dose generic eATG was similar to the standard dose generic eATG. We conclude that IST with low dose generic eATG and cyclosporine is an efficacious and economical approach that can potentially enhance treatment affordability in IAA patients. However, prospective studies with larger number of patients are needed to further validate these results. DisclosuresNo relevant conflicts of interest to declare.

A Mixed-chimerism Protocol Utilizing Thymoglobulin and Belatacept Did Not Induce Lung Allograft Tolerance, Despite Previous Success in Renal Allotransplantation.

In kidney transplantation, long-term allograft acceptance in cynomolgus macaques was achieved using a mixed-chimerism protocol based on the clinically available reagents, rabbit anti-thymocyte globulin (ATG), and belatacept. Here, we have tested the same protocol in cynomolgus macaques transplanted with fully allogeneic lung grafts. Five cynomolgus macaques underwent left orthotopic lung transplantation. Initial immunosuppression included equine ATG and anti-IL6RmAb induction, followed by triple-drug immunosuppression for 4 mo. Post-transplant, a nonmyeloablative conditioning regimen was applied, including total body and thymic irradiation. Rabbit ATG, belatacept, anti-IL6RmAb, and donor bone marrow transplantation (DBMT) were given, in addition to a 28-d course of cyclosporine. All immunosuppressant drugs were stopped on day 29 after DBMT. One monkey rejected its lung before DBMT due to AMR, after developing donor-specific antibodies. Two monkeys developed fatal post-transplant lymphoproliferative disorder, and both monkeys had signs of cellular rejection in their allografts upon autopsy. The remaining 2 monkeys showed severe cellular rejection on days 42 and 70 post-DBMT. Cytokine analysis suggested higher levels of pro-inflammatory markers in the lung transplant cohort, as compared to kidney recipients. Although the clinically applicable protocol showed success in kidney transplantation, the study did not show long-term survival in a lung transplant model, highlighting the organ-specific differences in tolerance induction.

Outcomes of Severe Seronegative Hepatitis-associated Aplastic Anemia: A Pediatric Case Series.

Hepatitis-associated aplastic anemia (HAAA) is a potentially life-threatening diagnosis without clear treatment guidelines. The goal of the study was to characterize the presentation, evaluation, histopathology, and outcomes of therapy in children with HAAA to guide future research and to develop standardized care guidelines for this rare disease. Retrospective chart review of 4 patients with HAAA who presented to Children's Hospital Colorado between 2016 and 2019 was conducted. Patient presentation, evaluation, bone marrow and liver pathology, interventions, and clinical course were collected. Immunohistochemistry of liver biopsies was performed. We treated 4 patients with HAAA without liver failure. All had evidence of systemic hyperinflammation and CD8+ T cell predominant liver tissue infiltration. One had a genetic mutation predisposing him to immune-mediated disease, but all other genetic testing was negative. In 3 of the 4 patients, hepatitis was poorly responsive to standard therapy with steroids, azathioprine, or tacrolimus; however, sustained biochemical remission of hepatitis was induced after more aggressive immunosuppressive therapies including Anti-Thymocyte Globulin (ATG) at standard immunosuppressive therapy (IST) dosing for severe Aplastic Anemia (sAA). Two patients underwent hematopoietic stem cell transplant (HSCT); 1 as first line therapy and 1 for refractory sAA. We found that ATG-based IST induced remission of hepatitis in patients with steroid-refractory HAAA. This is also an appropriate initial treatment for severe Aplastic Anemia, though may not prevent the need for HSCT. We propose that equine ATG based IST at standard dosing regimen for sAA is a therapy that in select cases can be considered early on in the treatment course and could lead to a sustained remission of both hepatitis and sAA. This should be considered in collaboration with a pediatric hematologist.

245 - Distal Equine Anti-Thymocyte Globulin (ATG) As an Adjunct to Reduced Intensity Conditioning and Posttransplantation Cyclophosphamide (PTCy) for Allogeneic Hematopoietic Cell Transplantation (HCT) in Patients with Benign and Malignant Disorders of T Cell Proliferation or Dysregulation

245 - Distal Equine Anti-Thymocyte Globulin (ATG) As an Adjunct to Reduced Intensity Conditioning and Posttransplantation Cyclophosphamide (PTCy) for Allogeneic Hematopoietic Cell Transplantation (HCT) in Patients with Benign and Malignant Disorders of T Cell Proliferation or Dysregulation

Evolution of Moderate Aplastic Anemia into Subclinical PNH/AA and Successful Treatment with Reduced Intensity Haplo-HSCT: A Pediatric Case Report

Introduction: Aplastic Anemia (AA) is diagnosis made after the exclusion of other acquired or inherited disease that can present with pancytopenia. In pediatric AA, there is often overlap with many other diseases including Paroxysmal Nocturnal Hemoglobinuria (PNH) and hypocellular myelodysplastic syndrome (MDS). The diagnosis is often difficult and can evolve. There are new tests and methodologies to guide diagnosis and treatment decision making. Case report: The patient is a previously healthy, 18-year-old Caucasian female referred for pancytopenia. Patient reported progressive fatigue and easy bruising for a month prior to evaluation. Initial white blood count was 2.4 x109/L, hemoglobin 9.7g/dl, platelets 39 x109/L, absolute neutrophil count (ANC) of 590, and absolute retic count 68 x 109/L. A bone marrow exam revealed a hypocellular marrow with 30% cellularity with no dysplasia or blasts on flow cytometry. Viral studies, folate and vitamin B12 levels were normal. Chromosomal analysis, Fluorescent In situ Hybridization (FISH) study for MDS, and telomere length assay were normal. A bone marrow failure (BMF) panel for sixty targeted genes showed no mutations associated with BMF. PNH studies by flow cytometry showed 2.6% erythroid, 2% granulocytes, 2.7% monocytes failed to express GPI associated anchoring proteins (GPI-APs) representing a small PNH clone, not unusual in patients with aplastic anemia (AA). Studies were c/w with moderate AA (mAA). Standard management of mAA is careful observation and treatment if the patient requires transfusions or ANC falls below 500. However, since our patient was soon starting college out of state, we decided to treat with Immunosuppressive Therapy (IST), consisting of equine Anti-thymocyte globulin (eATG) and Cyclosporine. At 24 weeks post IST, no response was observed and the patient was requiring more frequent platelet and red blood cell transfusions. Repeat PNH testing showed 2% erythroid, 5% monocytes and 4% granulocytes that were deficient in GPI-Aps (Table1). BM exam showed 60% cellularity that was consistent with a recovering marrow but there was relative erythroid hyperplasia, without evidence of dysplasia or blasts. At this time, with increasing marrow cellularity but persistent pancytopenia we began to strongly suspect MDS. However, repeat chromosomal analysis and FISH studies were normal and a Foundation One myeloid panel was negative for mutations associated with MDS. At 28 weeks post-IST, repeat BM exam revealed 70% cellularity, again with relative erythroid hyperplasia. At the same time PNH testing, showed that 1.3% erythrocytes, 5.6% granulocytes and 5.4% monocytes were negative for GPI-APs. We concluded that our patient evolved had from mAA to subclinical PNH/AA which accounted for the normocellular marrow. High Disease Activity (HDA) is defined as lactate dehydrogenase (LDH) ≥ 1.5 times upper limit of normal and is associated with large PNH clones. HDA can guide the use of eculizumab as pre-transplant therapy. (DeZern et al, 2012) Throughout the course of the disease, her LDH was normal. She did not have HDA and therefore, was not treated with eculizumab. Because of the normocellular marrow she was not eligible for CTN 1502-CHAMP study. However, the patient underwent reduced intensity conditioning (RIC) and a haplo paternal BMT, followed by post-transplant cyclophosphamide, as per CTN 1502- CHAMP. She tolerated her BMT well without major complications. She is now five months post-transplant, alive and well, fully engrafted with 100% donor chimerism and no signs of GVHD. Post-transplant PNH testing revealed all PNH clones were eliminated. Conclusion: This case illustrates the diagnostic challenges of patients presenting with pancytopenia and the overlap and possible evolution of disease classifications; new diagnostic testing including gene mutation screens to aid in diagnosis; new concepts such as HDA in PNH to help guide treatment decision making; and the successful use of RIC and haplo BMT in a patient with PNH/AA and a normocellular BM Disclosures No relevant conflicts of interest to declare.

Aplastic anemia in children: How good is immunosuppressive therapy?

Aplastic anemia (AA) is an uncommon disorder in children, with hematopoietic stem cell transplant being the 1st line therapy; immunosuppressive therapy (IST) is the alternative therapy and is the most commonly used modality of treatment. There is paucity of data from the developing countries regarding treatment outcome with IST. We aimed to assess the outcome of IST in children with AA. Data for 43 children treated with IST from January 2012 to January 2017 (5 years) were retrieved from clinic records. IST included equine antithymocyte globulin (ATG) along with cyclosporine A. Complete response, partial response and nonresponse was seen in 9 (21%), 14 (32.5%) and 20(46.5%) patients, respectively. The median time to best response in the whole cohort was 19.1 months. However, complete response occurred nearly 2-year post-IST. There was no difference in outcome related to severity of AA, the presence of PNH clone, higher ALC or different available brands of ATG. There was a significantly better rate of response (p value: .03) at 6 months in patients who went on to achieve a CR vs patients who achieved a final PR only. An overall response rate, including partial and complete response, of 53.5% was seen in our cohort with a 3-year OS of 63%. This is not at par to the outcome reported from developed nations. The available brands of ATG were similar in terms of response kinetics as well as survival. A delayed time to complete response with prolonged requirement of cyclosporine therapy was seen in the cohort.

The oral microbiome of patients undergoing treatment for severe aplastic anemia: a pilot study.

The microbiome, an intriguing component of the human body, composed of trillions of microorganisms, has prompted scientific exploration to identify and understand its function and role in health and disease. As associations between microbiome composition, disease, and symptoms accumulate, the future of medicine hinges upon a comprehensive knowledge of these microorganisms for patient care. The oral microbiome may provide valuable and efficient insight for predicting future changes in disease status, infection, or treatment course. The main aim of this pilot study was to characterize the oral microbiome in patients with severe aplastic anemia (SAA) during their therapeutic course. SAA is a hematologic disease characterized by bone marrow failure which if untreated is fatal. Treatment includes either hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST). In this study, we examined the oral microbiome composition of 24 patients admitted to the National Institutes of Health (NIH) Clinical Center for experimental SAA treatment. Tongue brushings were collected to assess the effects of treatment on the oral microbiome. Twenty patients received standard IST (equine antithymocyte globulin and cyclosporine) plus eltrombopag. Four patients underwent HSCT. Oral specimens were obtained at three time points during treatment and clinical follow-up. Using a novel approach to 16S rRNA gene sequence analysis encompassing seven hypervariable regions, results demonstrated a predictable decrease in microbial diversity over time among the transplant patients. Linear discriminant analysis or LefSe reported a total of 14 statistically significant taxa (p < 0.05) across time points in the HSCT patients. One-way plots of relative abundance for two bacterial species (Haemophilus parainfluenzae and Rothia mucilaginosa) in the HSCT group, show the differences in abundance between time points. Only one bacterial species (Prevotella histicola) was noted in the IST group with a p value of 0.065. The patients receiving immunosuppressive therapy did not exhibit a clear change in diversity over time; however, patient-specific changes were noted. In addition, we compared our findings to tongue dorsum samples from healthy participants in the Human Microbiome Project (HMP) database and found among HSCT patients, approximately 35% of bacterial identifiers (N = 229) were unique to this study population and were not present in tongue dorsum specimens obtained from the HMP. Among IST-treated patients, 45% (N = 351) were unique to these patients and not identified by the HMP. Although antibiotic use may have likely influenced bacterial composition and diversity, some literature suggests a decreased impact of antimicrobials on the oral microbiome as compared to their effect on the gut microbiome. Future studies with larger sample sizes that focus on the oral microbiome and the effects of antibiotics in an immunosuppressed patient population may help establish these potential associations.

Randomized Trials of Autologous Hematopoietic Stem Cell Transplantation for Diffuse Cutaneous Systemic Sclerosis: Systematic Review and Meta-Analysis with Trial Sequential Analysis of Overall Mortality

Background. Diffuse cutaneous systemic sclerosis (SSc) is a multi-system chronically progressive and debilitating autoimmune connective tissue disease affecting internal organs, characterized by a dysregulated immune system and the production of autoantibodies. Patients experience progressive cumulative mortality despite currently available immunosuppressive therapies.Objective. To assess the safety and efficacy of hematopoietic stem cell transplantation (SCT) with the research question: “what is the relative effect on overall mortality in patients with SSc and internal organ involvement treated with SCT compared to those treated with other available immunosuppressive therapies?”Design. Systematic review with meta-analysis of randomized controlled trials (RCTs), with trial sequential analysis (TSA) adjustment for random error and repetitive testing of sparse and accumulating data (Patel A et al BMJ 2014;349:g4561).Data sources. PubMed, PubMed Central, Web of Science, OvidSP, Cochrane central register of controlled trials (CENTRAL), clinicaltrials.gov, eudract.ema.europa.eu, controlled-trials.com, free Google search, relevant conference proceedings, hand searching of reference lists, and contact with authors as necessary. Search terms “systemic sclerosis” and “transplant”. The search was last updated on 21 July 2018.Eligibility criteria. RCTs of adult patients with SSc randomized to receive SCT compared with those who were randomized to receive a non-SCT treatment were included, if overall mortality outcome data were available.Data extraction. Two reviewers independently assessed articles for inclusion, extracted data to assess risk of bias, trial methods, patients, interventions, comparisons, and outcome. The relative risk (RR) of overall mortality was calculated using a random effects model accounting for clinical heterogeneity.Primary outcome measure. Overall mortality, using intension to treat (ITT) and per protocol (PP) analyses.Risk of Bias. Assessed using the Cochrane Risk of Bias Assessment Tool.Results. There were three eligible RCTs (ASSIST 2011, ASTIS 2014, SCOT 2018), including 250 patients followed for up to 7.8 years (156 patients in Europe and 94 in North America). All trials were open label and assessed as at unclear risk of bias. Peripheral blood stem cell collection: 2-4 g/m2 cyclophosphamide before reinfusion of thawed cryopreserved 2 million CD34+ cells/kg, or GCSF and CD34+ cell enrichment before reinfusion of thawed cells (median of 5.6 million cells/kg). Conditioning was cyclophosphamide 200 mg/kg with 6.5-7.5 mg/kg rabbit anti-thymocyte globulin (ATG) or 120 mg/kg with 8 Gy total body irradiation (TBI) (lung and kidney shielding with 2 Gy limit) and 90 mg/kg equine ATG. Supportive care included corticosteroids, angiotensin converting enzyme inhibitors (usually lisinopril), and aciclovir. Control group treatments comprised monthly cyclophosphamide, 0.5-1 g/m2, 6-12 infusions.Significant overall mortality benefit was observed in the SCT group, with both an ITT (RR 0.60, 95% confidence interval (CI) 0.40-0.90; P=0.01) and PP analysis (RR 0.52, 95% CI 0.33-0.83; P=0.006). Statistical heterogeneity was absent (I2=0%). SCT benefit was robust to TSA adjustment for both the ITT (RR 0.60, 95% CI 0.36-0.98; P=0.014; diversity adjusted information size (D2=0%) and PP analyses (RR 0.51, 95% CI 0.31-0.86; P=0.004; D2=0%). The information size for an ITT model had >70% power (Fig 1), while the PP model had >90% power (Fig 2). The corresponding number needed to treat (NNT) to prevent 1 death was 7 (95% CI 4-29) for the ITT analysis and 5 (95% CI 3-11) for the PP analysis.However, significantly higher CTCAE grade 3-4 infective (P<0.01) and hematological (P<0.01) adverse events were reported in the SCT group compared to control, with no difference for cardiovascular (P=0.92) and respiratory (P=0.24) events. More viral infection or reactivation events were reported in the SCT group compared to control (P=0.05): CMV (P=0.01), EBV (P=0.08), HSV (P=0.59). Importantly, subsequent malignancy was similar for both groups (P=0.96), 4-5%.Conclusions. Our analysis has sufficient information size to indicate that autologous SCT for patients with SSc and internal organ involvement is safe and efficacious. The magnitude of the reduction in long-term mortality of autologous SCT over other available therapies may be practice changing. DisclosuresNo relevant conflicts of interest to declare.

Renal Allograft Tolerance for End-Stage Renal Disease Patients with Hematologic Malignancies

The patients with end-stage renal disease (ESRD) associated with hematologic malignancy are unique as they are not eligible for kidney transplantation because of the malignancy and for bone marrow transplantation because of renal failure. In contrast to the ESRD patients without malignancy, induction of durable full or mixed chimerism is necessary to induce a graft versus tumor (GvT) effect. With durable chimerism, there is also a risk of GVHD. To achieve potent GvT responses and induce tolerance for the renal allograft, ten patients (median age: 50 years [range: 34-57 years]) with multiple myeloma and ESRD have undergone an HLA-matched combined kidney and bone marrow transplantation (CKBMT) with lead follow-up time of more than 19 years. The initial preparative regimen for HLA matched transplants consisted of high-dose cyclophosphamide (60mg/kg on days -6 and -5), equine antithymocyte globulin (Atgam 15-20 mg/kg on days -1, +1, +3 and +5) and pretransplant thymic irradiation (7Gy on day -1). Cyclosporine was tapered and discontinued as early as day 73 post-transplant. All ten patients achieved mixed chimerism. Two patients developed acute GVHD and three chronic GVHD after their initial transplant. Five of ten patients are alive, two with no evidence of myeloma from 7.2 to 19.2 years post-transplant. Three patients have normal or near-normal renal function without immunosuppression (IS). Two patients with normal renal function off IS were returned to IS because of chronic GVHD. The patient survival of our approach with HLA-matched CKBMT for refractory myeloma has been 100% at 3 years, which is superior to the reported survival of myeloma patients with dialysis dependent ESRD without CKBMT (25% at 3 years). The regimen for HLA matched CKBMT has been revised to a TBI-based conditioning which has consisted of TBI 2-4Gy on day -1, Atgam (20mg/kg on days -3, -1, +3 and +5) and post-transplant CNI. Two patients (one with myeloma and one with systemic AL amyloidosis and myelodysplastic syndrome) have been treated with this regimen. Both developed persistent full donor chimerism (one after a second transplant from the same donor for hematopoietic graft rejection) and are currently doing well without immunosuppression. This approach has recently been extended to HLA haplo-identical CKBMT using post-BMT cyclophosphamide for GVHD prophylaxis. The conditioning regimen consisted of pre- transplant conditioning with Thymoglobulin (replaced with fludarabine after the second patient), low-dose cyclophosphamide, and 2 Gy of TBI. GVHD prophylaxis was post-transplant high-dose cyclophosphamide (50 mg/kg/day on days +3 and +4) followed by tacrolimus and mycophenolate mofetil (MMF) starting on day +5. Five haplo-identical CKBMT have performed and two of them have been off immunosuppression. We conclude that CKBMT can provide both treatment for hematologic malignancy and renal allograft tolerance.

Allogeneic Matched Related Donor Bone Marrow Transplantation for Pediatric Patients With Severe Aplastic Anemia Using "Low-dose" Cyclophosphamide, ATG Plus Fludarabine.

The combination of cyclophosphamide (CY) and antithymocyte globulin (ATG) has been used as a standard conditioning regimen for matched related donor transplantation in patients with severe aplastic anemia. To decrease the regimen-related toxicity while maintaining appropriate engraftment and survival rates, fludarabine (FLU) was added to the regimen. Four pediatric patients received matched related donor bone marrow transplantation with CY (50 mg/kg×2) (instead of the 50 mg/kg×4 standard dosing), equine ATG (30 mg/kg×3), with the addition of FLU (30 mg/m×4). Graft versus host disease (GvHD) prophylaxis included a calcineurin inhibitor and methotrexate. No grade 4 acute toxicities occurred during the first 30 days after transplant. All patients engrafted with normalization of peripheral blood counts and transfusion independence. One patient developed grade 1 to 2 acute GvHD, followed by chronic GvHD that resolved. With a median follow-up of 41.7 months, all 4 patients are alive and transfusion free, with complete donor chimerism. This combination of a low-dose CY/ATG+FLU regimen was overall very well tolerated and contributed toward a successful outcome including engraftment, chimerism, and survival. This small pilot study shows that this cytoreductive regimen could be considered as the standard of care for transplantation of pediatric patients with aplastic anemia from HLA-matched siblings.