Rabbit Antithymocyte Globulin Research Articles

Influence of induction therapy and antiretroviral regimen on outcomes in kidney transplant recipients living with human immunodeficiency.

Kidney transplantation has a survival benefit for people with human immunodeficiency virus (HIV) and end-stage kidney disease, however increased rates of rejection remain an issue. Questions remain regarding the impact of induction immunosuppression therapy and antiretroviral (ARV) choice on long-term outcomes. We performed a multicenter retrospective analysis of outcomes in recipients with HIV who received kidneys from donors without HIV transplanted between 2004 and 2019. The association between induction and ARV regimens and long-term outcomes including rejection, graft, and recipient survival over 5 years was investigated using Cox regression modeling. Seventy-eight kidney transplants (KT) performed in 77 recipients at five US transplant centers were included, with median follow up of 7.1 (4.3-10.7) years. Overall recipient and graft survival were 83% and 67%, respectively. Rejection occurred in 37% (29/78). Recipients with rejection were more likely to be younger, recipients of deceased donor organs, and Black. Receipt of rabbit anti-thymocyte globulin (rATG) induction without protease-inhibitor (PI)-based ARVs was associated with 83% lower risk of rejection (adjusted hazard ratio (aHR) 0.17 (95% CI 0.05-0.63), p =.007) and a non-statistically significantly lower risk of graft failure (aHR 0.18 (0.03-1.16), p =.07) when compared to those who received other induction and ARV combinations. In this multicenter retrospective study, we found a trend toward lower rejection and improved graft survival among those who received both rATG for induction and PI-sparing ARVs.

Clinical outcomes of patients receiving three versus four doses of methotrexate with concomitant antithymocyte globulin in match unrelated donor allogeneic stem cell transplant: A single‐center experience

AbstractMethotrexate (MTX) doses on days +1, +3, +6, and +11 after match unrelated donor allogeneic stem cell transplant (MUD HSCT) is a common graft‐versus‐host disease (GVHD) prophylaxis regimen. However, the overlapping toxicity of MTX with conditioning chemotherapy sometimes warrants the omission of the fourth dose of MTX. Prior single‐institution studies showed conflicting results comparing the outcomes of patients who received three versus four doses of MTX, but to our knowledge, the effect of concomitant antithymocyte globulin (ATG) has not been reported. Charts of patients who underwent MUD HSCT between 2009 and 2023 were reviewed. Patients received rabbit ATG (Thymoglobulin), given at 0.5 mg/kg on day −3, 2 mg/kg on day −2, and 2.5 mg/kg on day −1. MTX is given at 15 mg/m2 on day +1 and 10 mg/m2 on days +3, +6, and +11. Severe mucositis was the most common indication for day +11 MTX omission (82%). We identified 292 patients (116 in 3 dose cohort and 176 in 4 dose cohort). Median follow‐up was 23 months (range 1–151). Patients in the 4 doses cohort were more frequently male (68% vs. 50%, p < 0.01), received a reduced intensity conditioning regimen (38.0% vs. 22%, p < 0.01), were older (median 58 vs. 54 years, p = 0.02), and received a transplant in the earlier era (median HSCT year 2014 vs. 2018, p < 0.01). A statistically significant difference was not evidenced between the cohorts for the following outcomes: acute GVHD (aGVHD) (HR 1.1, 95% CI 0.9–1.5), chronic GVHD (cGVHD) (HR 1.3, 95% CI 0.8–1.6), relapse‐free survival (RFS) (HR 1.0, 95% CI 0.6–1.5), non‐relapse mortality (NRM) (HR 1.4, 95% CI 0.9–2.2), and overall survival (OS) (HR 1.2, 95% CI 0.9–1.7). Both cohorts had similar median time to neutrophil engraftment at 14 days. When ATG is incorporated, omission of day +11 MTX does not significantly impact the rate of engraftment or cumulative incidence of aGVHD, cGVHD, RFS, NRM, and OS.

The state of the art in the treatment of severe aplastic anemia: immunotherapy and hematopoietic cell transplantation in children and adults.

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure where marrow disruption is driven by a cytotoxic T-cell-mediated autoimmune attack against hematopoietic stem cells. The key diagnostic challenge in children, but also in adults, is to exclude the possible underlying congenital condition and myelodysplasia. The choice of treatment options, either allogeneic hematopoietic cell transplantation (alloHCT) or immunosuppressive therapy (IST), depends on the patient's age, comorbidities, and access to a suitable donor and effective therapeutic agents. Since 2022, horse antithymocyte globulin (hATG) has been available again in Europe and is recommended for IST as a more effective option than rabbit ATG. Therefore, an update on immunosuppressive strategies is warranted. Despite an improved response to the new immunosuppression protocols with hATG and eltrombopag, some patients are not cured or remain at risk of aplasia relapse or clonal evolution and require postponed alloHCT. The transplantation field has evolved, becoming safer and more accessible. Upfront alloHCT from unrelated donors is becoming a tempting option. With the use of posttransplant cyclophosphamide, haploidentical HCT offers promising outcomes also in AA. In this paper, we present the state of the art in the management of severe AA for pediatric and adult patients based on the available guidelines and recently published studies.

(1114) - Weight-Adjusted Rabbit Antithymocyte Globulin Induction and Outcomes in Heart Transplantation

(1114) - Weight-Adjusted Rabbit Antithymocyte Globulin Induction and Outcomes in Heart Transplantation

Comparison of rabbit ATLG and ATG for GVHD prophylaxis in hematological malignancies with haploidentical hematopoietic stem cell transplantation.

Rabbit anti-human T lymphocyte globulin (ATLG) and anti-thymocyte globulin (ATG) are commonly used for graft-versus-host disease (GVHD) prophylaxis in allogeneic hematopoietic stem cell transplantation (HSCT). Yet, their efficacy and safety have seldom been compared in hematological malignancies with haploidentical HSCT. A retrospective analysis with 28 ATLG (total dosage, 20-30mg/kg) and 18 ATG (total dosage, 8-10mg/kg) patients were performed. The cumulative incidences of chronic GVHD and relapse were comparable between both groups. ATLG showed a trend towards a lower acute GVHD incidence (28.6% vs. 44.4%, P = 0.242) and 3-year non-relapse mortality (10.7% vs. 27.8%, P = 0.160), and had a significantly higher 3-year overall survival (OS, 64.3% vs. 33.3%, P = 0.033) and GVHD-free and relapse-free survival (GRFS, 32.1% vs. 11.1%, P = 0.045) compared with ATG. Multivariate Cox regression analysis demonstrated ATLG was independently associated with a favorable OS (hazard ratio [HR] = 0.37, 95% confidence interval [CI]: 0.16-0.86, P = 0.020) and GRFS (HR = 0.51, 95%CI: 0.26-1.00, P = 0.051). Furthermore, ATLG had a lower risk of fever (25.0% vs. 61.1%, P = 0.014) and hemorrhage cystitis (7.1% vs. 38.9%, P = 0.008) than ATG-T. In conclusion, ATLG confers more survival benefit and a better safety profile than ATG and can be used in hematological malignancies with haploidentical HSCT. Prospective designed trials with a larger sample size are warranted to confirm the results in the future.

ATG or post-transplant cyclophosphamide to prevent GVHD in matched unrelated stem cell transplantation?

There is a high risk of GVHD and non-relapse mortality (NRM) after allogeneic stem cell transplantations (alloSCT) from unrelated donors. Prophylaxis with rabbit anti-thymocyte globulin (rATG) is standard in Europe but post-transplantation Cyclophosphamide (PTCy) is an emerging alternative. We analyzed outcomes of rATG (n = 7725) vs. PTCy (n = 1039) prophylaxis in adult patients with hematologic malignancies undergoing peripheral blood alloSCT from 10/10 antigen-matched unrelated donors (MUD) between January 2018 and June 2021 in the EBMT database. The provided P-values and hazard ratios (HR) are derived from multivariate analysis. Two years after alloSCT, NRM in the PTCy group was 12.1% vs. 16.4% in the rATG group; p = 0.016; HR 0.72. Relapse was less frequent after PTCy vs. rATG (22.8% vs. 26.6%; p = 0.046; HR 0.87). Overall survival after PTCy was higher (73.1% vs. 65.9%; p = 0.001, HR 0.82). Progression free survival was better after PTCy vs. rATG (64.9% vs. 57.2%; p < 0.001, HR 0.83). The incidence of chronic GVHD was lower after PTCy (28.4% vs. rATG 31.4%; p = 0.012; HR 0.77), whereas the incidence and severity of acute GVHD were not significantly different. GVHD-free relapse-free survival was significantly higher in the PTCy arm compared to the rATG arm (2 y incidence: 51% vs. 45%; HR: 0.86 [95% CI 0.75–0.99], p = 0.035). In the absence of evidence from randomized controlled trials, our findings support a preference for the use of PTCy in adult recipients of peripheral blood alloSCTs from MUD.

PTCy versus ATG as graft-versus-host disease prophylaxis in mismatched unrelated stem cell transplantation

There is an increased risk of GVHD and of non-relapse mortality (NRM) after allogeneic stem cell transplantations (alloSCT) when mismatched unrelated donors (MMUD) are used. In Europe, it is standard practice to use rabbit anti-thymocyte globulin (rATG) to reduce the high NRM and GVHD risks after MMUD alloSCT. As an alternative to rATG, post-transplantation Cyclophosphamide (PTCy) is in increasing clinical use. It is currently impossible to give general recommendations regarding preference for one method over another since comparative evidence from larger data sets is lacking. To improve the evidence base, we analyzed the outcome of rATG vs. PTCy prophylaxis in adult patients with hematologic malignancies undergoing first peripheral blood alloSCT from MMUD (9/10 antigen match) between Jan 2018 and June 2021 in the database of the European Society for Blood and Marrow Transplantation (EBMT). We performed multivariate analyses using the Cox proportional-hazards regression model. We included 2123 patients in the final analyses (PTCy, n = 583; rATG, n = 1540). p values and hazard ratios (HR) presented here are multivariate outcomes. Two years after alloSCT we found a lower NRM in the PTCy group of 18% vs. 24.9% in the rATG group; p = 0.028, HR 0.74. Overall survival in the PTCy cohort was higher with 65.7% vs. 55.7% in the rATG cohort; p < 0.001, HR 0.77. Progression-free survival was also better in the PTCy patients with 59.1% vs. 48.8% when using rATG; p = 0.001, 0.78. The incidences of chronic GVHD and acute GVHD were not significantly different between the groups. We found significantly lower NRM as well as higher survival in recipients of peripheral blood alloSCTs from MMUD receiving PTCy as compared to rATG. The results of the current analysis suggest an added value of PTCy as GVHD prophylaxis in MMUD alloSCT.

Impact of Cumulative 6 mg/kg Antithymocyte Globulin on Early Posttransplant Outcomes in Kidney Transplant Recipients with Delayed Graft Function.

Introduction: Delayed graft function in kidney transplant is associated with an increased risk of rejection and graft loss. Use of rabbit antithymocyte globulin induction in delayed graft function has been correlated with less rejection compared to basiliximab, but optimal dosing remains unknown. Program Evaluation Aims: The purpose of this evaluation was to retrospectively assess the short-term effectiveness and tolerability of a clinical protocol that increased the net state of immunosuppression in delayed graft function kidney transplant recipients using cumulative 6 mg/kg rabbit antithymocyte globulin induction. Design: This retrospective cohort included 88 kidney transplant recipients with delayed graft function, transplanted between January 2017 and March 2021, who either received cumulative 4.5 mg/kg pre-protocol or 6 mg/kg post-protocol rabbit antithymocyte globulin. Outcomes evaluated were biopsy-proven acute rejection and incidence of graft loss, infection, and cytopenia at 6 months. Results: A significant reduction of biopsy-proven acute rejection incidence occurred post-protocol implementation (10/33, 30.3% vs 6/55, 10.9%; P = .04). Of those with rejection, significantly less post-protocol patients were classified as acute cellular rejection (9/10, 90.0% vs 2/6, 33.3%; P = .04). No death-censored graft loss was observed in either group. Rates of cytopenia and infection were similar pre- versus post-protocol implementation. Conclusion: Increasing the exposure to rabbit antithymocyte globulin and maintenance immunosuppression in delayed graft function kidney transplant recipients was tolerable and significantly reduced rejection occurrence at 6 months.

Outcomes of haploidentical peripheral blood stem cell transplantation following myeloablative conditioning using two types of rabbit ATG: a propensity score-matched analysis.

During hematopoietic stem cell transplantation (HSCT), ATG depletes T cells in-vivo to improve engraftment and prevent graft-versus-host disease (GVHD). Here, we compared the clinical efficacy of two different types of ATGs: thymoglobulin and anti-human T-lymphocyte immunoglobulin (Grafalon). A total of 469 patients who received haploidentical transplantation were enrolled in this retrospective study. We applied a propensity score (PS)-matched analysis and 209 patients were assigned to each group. Clinical outcomes were compared between two groups and primary outcome was overall survival (OS). There was no significant difference in OS between two groups. Within the first 180days after HSCT, Grafalon was associated with lower incidences of Epstein-Barr virus (EBV) viremia (31.6 vs. 54.5%, P < 0.0001) and cytomegalovirus viremia (CMV) viremia (54.5 vs. 67.9%, P = 0.005) compared to thymoglobulin. Patients receiving Grafalon had a higher rate of moderate/severe chronic GVHD (26.3 vs. 18.2%, P = 0.046). However, the incidences of engraftment failure, grade II-IV acute GVHD, relapse, non-relapse mortality (NRM), and GVHD-free relapse-free survival (GRFS) did not differ greatly between groups. In the subgroup analysis, Grafalon improved the OS of lymphoid malignancies with young ages (< 40years old) (HR, 0.55; P = 0.04) or with a high/very high disease risk index (HR, 0.36; P = 0.04). In the myeloid cohort, Grafalon reduced NRM in the patients who received non-female for male transplantation grafts (HR, 0.17; P = 0.02). Our results suggest the two types of ATG may differentially influence transplant outcomes and it may optimize ATG selection according to the condition of patients.

Gut Immunomodulation with Vedolizumab prior to Allogeneic Hematopoietic Stem Cell Transplantation in Pediatric Patients with Inflammatory Bowel Disease

Inborn errors of immunity (IEI) are often associated with inflammatory bowel disease (IBD). IEI can be corrected by allogeneic hematopoietic stem cell transplantation (HSCT); however, peritransplantation intestinal inflammation may increase the risk of gut graft-versus-host disease (GVHD). Vedolizumab inhibits the homing of lymphocytes to the intestine and may attenuate gut GVHD, yet its role in preventing GVHD in pediatric patients with IEI-associated IBD has not been studied. Here we describe a cohort of pediatric patients with IEI-associated IBD treated with vedolizumab before and during allogeneic HSCT. The study involved a retrospective chart review of pediatric patients with IEI-associated IBD treated with vedolizumab at 6 weeks, 4 weeks, and 1 week before undergoing HSCT. The conditioning regimen consisted of treosulfan, fludarabine, and cyclophosphamide with rabbit antithymocyte globulin, and GVHD prophylaxis included tacrolimus and steroids. Eleven patients (6 females) with a median age of 5 years (range, .4 to 14 years) with diverse IEI were included. IBD symptoms were characterized by abdominal pain, loose stools, and blood in stools. Four patients had developed a perianal fistula, and 1 patient had a rectal prolapse. One patient had both a gastrostomy tube and a jejunal tube in situ. Treatment of IBD before HSCT included steroids in 11 patients, anakinra in 2, infliximab in 4, sulfasalazine in 2, mesalazine in 2, and vedolizumab. IBD symptoms were considered controlled in the absence of abdominal pain, loose stools, or blood in stools. Graft sources for HSCT were unrelated donor cord in 5 patients (2 with a 5/8 HLA match, 2 with a 7/8 match, and 1 with a 6/8 match), peripheral blood stem cells in 5 patients (2 haploidentical, 1 with a 9/10 HLA match, and 2 with a 10/10 match), and bone marrow in 1 patient (10/10 matched sibling donor). The median number of vedolizumab infusions was 4 (range, 3 to 12) before HSCT and 1 (range, 1 to 3) after HSCT, and all were reported to be uneventful. All patients had engrafted. Acute GVHD occurred in 4 patients and was limited to grade I skin GVHD only. Chronic GVHD occurred in 1 patient and again was limited to the skin. There was no gut GVHD. Three patients experienced cytomegalovirus viremia, and 2 patients had Epstein-Barr virus viremia. At the time of this report, all patients were alive with no evidence of IBD at a median follow-up of 15 months (range, 3 to 39 months). Administration of vedolizumab pre- and post-HSCT in pediatric patients with IEI-associated IBD is well tolerated and associated with a low rate of gut GVHD. These findings provide a platform for the prospective study and use of vedolizumab for GVHD prophylaxis in pediatric patients with known intestinal inflammation as a pre-HSCT comorbidity.

The impact of induction therapy on the risk of posttransplant lymphoproliferative disorder in adult kidney transplant recipients with donor-recipient serological Epstein-Barr virus mismatch

Posttransplant lymphoproliferative disorder (PTLD) poses a significant concern in Epstein-Barr virus (EBV)–negative patients transplanted from EBV-positive donors (EBV R-/D+). Previous studies investigating the association between different induction agents and PTLD in these patients have yielded conflicting results. Using the Organ Procurement and Transplant Network database, we identified EBV R-/D+ patients >18 years of age who underwent kidney-alone transplants between 2016 and 2022 and compared the risk of PTLD with rabbit antithymocyte globulin (ATG), basiliximab, and alemtuzumab inductions. Among the 6620 patients included, 64.0% received ATG, 23.4% received basiliximab, and 12.6% received alemtuzumab. The overall incidence of PTLD was 2.5% over a median follow-up period of 2.9 years. Multivariable analysis demonstrated that the risk of PTLD was significantly higher with ATG and alemtuzumab compared with basiliximab (adjusted subdistribution hazard ratio [aSHR] = 1.98, 95% confidence interval [CI] 1.29-3.04, P = .002 for ATG and aSHR = 1.80, 95% CI 1.04-3.11, P = .04 for alemtuzumab). However, PTLD risk was comparable between ATG and alemtuzumab inductions (aSHR = 1.13, 95% CI 0.72-1.77, P = .61). Therefore, the risk of PTLD must be taken into consideration when selecting the most appropriate induction therapy for this patient population.

Immunosuppression withdrawal in living-donor renal transplant recipients following induction with antithymocyte globulin and rituximab: Results of a prospective clinical trial

Durable tolerance in kidney transplant recipients remains an important but elusive goal. We hypothesized that adding B cell depletion to T cell depletion would generate an immune milieu postreconstitution dominated by immature transitional B cells, favoring tolerance. The Immune Tolerance Network ITN039ST Research Study of ATG and Rituximab in Renal Transplantation was a prospective multicenter pilot study of live donor kidney transplant recipients who received induction with rabbit antithymocyte globulin and rituximab and initiated immunosuppression (IS) withdrawal (ISW) at 26 weeks. The primary endpoint was freedom from rejection at 52 weeks post-ISW. Six of the 10 subjects successfully completed ISW. Of these 6 subjects, 4 restarted immunosuppressive medications due to acute rejection or recurrent disease, 1 remains IS-free for over 9 years, and 1 was lost to follow-up after being IS-free for 42 weeks. There were no cases of patient or graft loss. CD19+ B cell frequencies returned to predepletion levels by 26 weeks posttransplant; immunoglobulin D+CD27--naïve B cells predominated. In contrast, memory cells dominated the repopulation of the T cell compartment. A regimen of combined B and T cell depletion did not generate the tolerogenic B cell profile observed in preclinical studies and did not lead to durable tolerance in the majority of kidney transplant recipients.

First-in-human Study With LIS1, a Next-generation Porcine Low Immunogenicity Antilymphocyte Immunoglobulin in Kidney Transplantation.

Polyclonal rabbit antithymocyte globulins (ATGs) are commonly used in organ transplantation as induction. Anti-N-glycolylneuraminic acid carbohydrate antibodies which develop in response to rabbit carbohydrate antigens might lead to unwanted systemic inflammation. LIS1, the first new generation of antilymphocyte globulins (ALGs) derived from double knockout swine, lacking carbohydrate xenoantigens was already tested in nonhuman primates and rodent models. This open-label, single-site, dose escalation, first-in-human, phase 1 study evaluated the safety, T cell depletion, pharmacokinetics, and pharmacodynamics of LIS1. In an ascending dose cohort (n = 5), a primary kidney transplant recipient at low immunologic risk (panel reactive antibody [PRA] < 20%), received LIS1 for 5 d at either 0.6, 1, 3, 6, or 8 mg/kg. After each patient completed treatment, the data safety monitoring board approved respective dose escalation. In the therapeutic dose cohort (n = 5) in patients with PRA <50% without donor specific antibodies, 2 patients received 8 mg/kg and 3 patients 10 mg/kg. CD3+ T cell depletion <100/mm3 at day 2 was observed in all patients who received 6, 8, and 10 mg/kg of LIS1. The terminal half-life of LIS1 was 33.7 d with linearity in its disposition. Lymphocyte repopulation was fast and pretransplant lymphocyte subpopulation counts recovered within 2-4 wk. LIS1 was well tolerated, neither cytokine release syndrome nor severe thrombocytopenia or leukopenia were noticed. Antibodies to LIS1 were not detected. In this first-in-human trial, genome-edited swine-derived polyclonal LIS1 ALG was well tolerated, did not elicit antidrug antibodies, and caused time-limited T cell depletion in low- and medium-risk kidney transplant recipients.

Impact of rabbit anti-thymocyte globulin (ATG) exposure on outcomes after ex vivo T-cell–depleted hematopoietic cell transplantation in pediatric and young adult patients

Background aimsTraditional weight-based dosing of rabbit anti-thymocyte globulin (rATG) used in allogeneic hematopoietic cell transplantation (HCT) to prevent graft-versus-host disease (GVHD) and graft rejection leads to variable exposures. High exposures induce delayed CD4+immune reconstitution (CD4+IR) and greater mortality. We sought to determine the impact of rATG exposure in children and young adults receiving various types of EX-VIVO T-cell–depleted (EX-VIVO-TCD) HCT. MethodsPatients receiving their first EX-VIVO-TCD HCT (CliniMACS CD34+, Isolex or soybean lectin agglutination), with removal of residual T cells by E-rosette depletion (E-) between 2008 and 2018 at Memorial Sloan Kettering Cancer Center were retrospectively analyzed. rATG exposure post-HCT was estimated (AU*d/L) using a validated population pharmacokinetic model. Previously defined rATG-exposures, <30, 30–55, ≥55 AU*d/L, were related with outcomes of interest. Cox proportional hazard and cause-specific models were used for analyses. ResultsIn total, 180 patients (median age 11 years; range 0.1–44 years) were included, malignant 124 (69%) and nonmalignant 56 (31%). Median post-HCT rATG exposure was 32 (0–104) AU*d/L. Exposure <30 AU*d/L was associated with a 3-fold greater probability of CD4+IR (P < 0.001); 2- to 4-fold lower risk of death (P = 0.002); and 3- to 4-fold lower risk of non-relapse mortality (NRM) (P = 0.02). Cumulative incidence of NRM was 8-fold lower in patients who attained CD4+IR compared with those who did not (P < 0.0001). There was no relation between rATG exposure and aGVHD (P = 0.33) or relapse (P = 0.23). Effect of rATG exposure on outcomes was similar in three EX-VIVO-TCD methods. ConclusionsIndividualizing rATG dosing to target a low rATG exposure post-HCT while maintaining total cumulative exposure may better predict CD4+IR, reduce NRM and increase overall survival, independent of the EX-VIVO-TCD method.

Safety and efficacy of autologous haematopoietic stem-cell transplantation with low-dose cyclophosphamide mobilisation and reduced intensity conditioning versus standard of care in refractory Crohn's disease (ASTIClite): an open-label, multicentre, randomised controlled trial

A previous controlled trial of autologous haematopoietic stem-cell transplantation (HSCT) in patients with refractory Crohn's disease did not meet its primary endpoint and reported high toxicity. We aimed to assess the safety and efficacy of HSCT with an immune-ablative regimen of reduced intensity versus standard of care in this patient population. This open-label, multicentre, randomised controlled trial was conducted in nine National Health Service hospital trusts across the UK. Adults (aged 18-60 years) with active Crohn's disease on endoscopy (Simplified Endoscopic Score for Crohn's Disease [SES-CD] ulcer sub-score of ≥2) refractory to two or more classes of biological therapy, with no perianal or intra-abdominal sepsis or clinically significant comorbidity, were recruited. Participants were centrally randomly assigned (2:1) to either HSCT with a reduced dose of cyclophosphamide (intervention group) or standard care (control group). Randomisation was stratified by trial site by use of random permuted blocks of size 3 and 6. Patients in the intervention group underwent stem-cell mobilisation (cyclophosphamide 1 g/m2 with granulocyte colony-stimulating factor (G-CSF) 5 μg/kg) and stem-cell harvest (minimum 2·0 × 106 CD34+ cells per kg), before conditioning (fludarabine 125 mg/m2, cyclophosphamide 120 mg/kg, and rabbit anti-thymocyte globulin [thymoglobulin] 7·5 mg/kg in total) and subsequent stem-cell reinfusion supported by G-CSF. Patients in the control group continued any available conventional, biological, or nutritional therapy. The primary outcome was absence of endoscopic ulceration (SES-CD ulcer sub-score of 0) without surgery or death at week 48, analysed in the intention-to-treat population by central reading. This trial is registered with the ISRCTN registry, 17160440. Between Oct 18, 2018, and Nov 8, 2019, 49 patients were screened for eligibility, of whom 23 (47%) were randomly assigned: 13 (57%) to the intervention group and ten (43%) to the control group. In the intervention group, ten (77%) participants underwent HSCT and nine (69%) reached 48-week follow-up; in the control group, nine (90%) reached 48-week follow-up. The trial was halted in response to nine reported suspected unexpected serious adverse reactions in six (46%) patients in the intervention group, including renal failure due to proven thrombotic microangiopathy in three participants and one death due to pulmonary veno-occlusive disease. At week 48, absence of endoscopic ulceration without surgery or death was reported in three (43%) of seven participants in the intervention group and in none of six participants in the control group with available data. Serious adverse events were more frequent in the intervention group (38 in 13 [100%] patients) than in the control group (16 in four [40%] patients). A second patient in the intervention group died after week 48 of respiratory and renal failure. Although HSCT with an immune-ablative regimen of reduced intensity decreased endoscopic disease activity, significant adverse events deem this regimen unsuitable for future clinical use in patients with refractory Crohn's disease. Efficacy and Mechanism Evaluation Programme, a Medical Research Council and National Institute for Health Research partnership.

Predictive value of thyroid function in severe aplastic anemia patients treated with immunosuppressive therapy.

To explore the predictive value of thyroid function in severe aplastic anemia (SAA) patients treated with immunosuppressive therapy (IST), 149 SAA patients in our center were enrolled between February 2015 and June 2020 in this study. We assessed the thyroid function of 134 patients without primary thyroid diseases, and discovered that 89 patients were accompanied by abnormal thyroid hormone, especially low triiodothyronine (T3). Patients with higher pretreatment-free T3 (FT3) levels (>5 pmol/L) demonstrated superior response rates at 3 and 6 months after IST compared to those with lower FT3 levels (54.5% vs 35.4%, P = .020; 67.3% vs 46.9%, P = .020). Multivariate analysis indicated that shorter disease duration (≤56 days) and response at 6 months were independent favorable factors of overall survival (relative risk [RR] = 2.66, 95% confidence interval [CI] = 1.03-6.90, P = .040; RR = 30.10, 95% CI = 4.02-225.66, P = .001). The 6-year failure-free survival (FFS) was 53.8% (95% CI = 40.9%-65.1%). Multivariate analysis revealed that patients with a response at 6 months, shorter duration (≤56 days) and receiving rabbit antithymocyte globulin (ATG) had better FFS outcomes than those without a response at 6 months, with a longer duration and receiving porcine ATG (RR = 22.6, 95% CI = 7.9-64.9, P < .001; RR = 2.4, 95% CI = 1.3-4.5, P = .006; RR = 2.5, 95% CI = 1.1-5.8, P = .030). In conclusion, FT3 levels reflect the severity of SAA, and patients with higher FT3 levels (>5 pmol/L) had superior response rates than those with lower ones.

Immunoglobulin A Deposits In Renal Allografts: A Prospective Longitudinal Single-Center Study

Aims and ObjectivesTo describe the prevalence of IgA deposits in renal allografts in a cohort of renal transplant recipients and to analyse their management strategies and histopathology.To assess graft function and proteinuria after 1 year of follow up. Materials and MethodsA Prospective longitudinal follow up study carried out in VPS Lakeshore Hospital and Research Centre, Kochi, Kerala over a period of five years (July 2015 to June 2020). Kidney transplant recipients with allograft biopsies that reported IgA deposits (IgAD) on immunofluorescence were included in the study. Light microscopy and immunofluorescence studies were performed. MEST-C Scoring was done in patients with pathogenic IgA deposits. Treatment strategies included increased baseline steroid dosage, rituximab administration and plasma exchange. Clinical details and management strategies were analysed and patients were followed up for 1 year after diagnosis. Changes in graft function (S. Creatinine) and proteinuria (Urine Protein/Creatinine ratio) was analysed. Clinico-pathological correlation with the MEST-C scores was also done. ResultsOut of 1036 kidney transplants done in the study period, 760 graft biopsies were performed. 64 cases had post transplant deposition of IgA (8%). Mean age was 45±11.25SD years. The study had 51 males and 13 females. Induction immunosuppression comprised of rabbit antithymocyte globulin in 29 (45%) patients and basiliximab in 35 (54%). Maintenance immunosuppression in all comprised of tacrolimus, mycophenolate mofetil and steroids. There were 2 groups: Group A (pathogenic IgAD) and Group B (incidental IgAD). Group A had 46 cases (71.9%), out of which 8 had ‘active’ IgA nephropathy (endocapillary proliferation, crescents and IgA vasculitis), and 38 had ‘inactive’ IgA deposits. In patients with active deposits, 3 had cellular crescents (18%, 30% and 23%), all 8 had endocapillary proliferation and 2 had vasculitis. Group B had 18 cases (28.1%), comprising T cell mediated rejections (5), antibody mediated rejection (8), BK virus nephropathy (1) and interstitial fibrosis and tubular atrophy (4). In Group A, 22 (47.8%) presented with graft dysfunction, 8 (17.3%) with isolated proteinuria and 14 (30.4%) patients presented with a combination. 2 (4.3%) patients had neither. 14 (30.4%) presented within 1 month of renal transplant. In patients of group A, at the end of 1 year of treatment, mean S. Creatinine reduced to 1.68mg/dl from 1.84mg/dl and the mean protein/creatinine ratio reduced from 1.2 to 0.5. (±1.17). In patients with ‘active IgA’ lesions, at the end of 1 year of treatment mean S. Creatinine increased slightly to 1.68mg/dl (±0.47SD) from 1.48mg/dl (±0.52SD) and the mean protein/creatinine ratio reduced from 2.32 (±1.56SD) to 1.05. (±1.70SD). In the 16 patients with IgA deposits and proteinuria, at the end of 1 year of treatment mean S. Creatinine decreased to 1.41 ±0.32 SD mg/dl from 1.47±0.37SD mg/dl and the mean protein/creatinine ratio reduced from 1.12±1.31 SD to 0.39±0.75 SD. In the remaining 22 patients with acute tubular injury, at the end of 1 year mean S. Creatinine decreased to 1.92 ±0.32 SD mg/dl from 2.1±0.8SD mg/dl and the mean protein/creatinine ratio reduced from 1.1±1.31 SD to 0.66±1.45 SD. In MEST-C scoring analysis, all scores were 0 in 20 (43.4%) biopsies, only M1 score in 11 (23.9%) biopsies, only E1 score in 10 biopsies (21.7%), S1 in 13 (28.2%) cases. ConclusionsImmunoglobulin A deposits occur commonly after transplant, these may represent recurrence, de novo IgA or donor derived IgA deposits. Although commonly benign, some may cause significant graft dysfunction and graft loss. IgA deposition can present as varying combinations of graft dysfunction and proteinuria. Active IgA pathologies may occur early in the post transplant course, may have significant graft dysfunction and need proactive management. There is correlation between segmental sclerosis and proteinuria. Evidence for efficacy of Rituximab, plasma exchange and prolonged courses of steroids is wanting, however some benefit is possible. Long term follow up is essential.

Porcine antilymphocyte globulin versus rabbit antithymocyte globulin for intensive immunosuppressive therapy of acquired aplastic anemia: A meta-analysis and systematic review.

Several studies have reported that porcine antilymphocyte globulin (pALG) has a significant effect on aplastic anemia (AA), but their conclusions are inconsistent. To objectively evaluate its efficacy and safety, a meta-analysis was conducted. We systematically searched the relevant literature on pALG vs. rabbit antithymocyte globulin (rATG) as the first-line treatment in AA patients until August 31, 2022, in electronic databases: PubMed, Cochrane Library, Web of Science, etc. Two researchers independently extracted data and evaluated the quality of the study. Stata 14.0 was used for statistical analysis. 50 studies were included in the analysis. The overall responses at 3, 6, and 12 months between the pALG group and rATG group were equivalent. We analyzed early mortality, total mortality, relapse rates, and 5-year survival after the administration of pALG or rATG, and there was no significant difference between the pALG and rATG groups. In our study, the incidence of infection in the pALG group was better than that in the rATG group, OR=0.63, 95% CI (0.44-0.88), p=0.008, which showed a statistically significant difference. The efficacy of pALG in AA patients is equivalent to that of rATG. rATG was associated with a significantly higher incidence rate of infection than pALG.

T-cell receptor sequencing reveals selected donor-reactive CD8+ T cell clones resist antithymocyte globulin depletion after kidney transplantation

High frequencies of donor-reactive memory T cells in the periphery of transplant candidates prior to transplantation are linked to the development of posttransplant acute rejection episodes and reduced allograft function. Rabbit antithymocyte globulin (rATG) effectively depletes naïve CD4+ and CD8+ T cells for >6 months posttransplant, but rATG’s effects on human donor-reactive T cells have not been carefully determined. To address this, we performed T cell receptor β-chain sequencing on peripheral blood mononuclear cells aliquots collected pretransplant and serially posttransplant in 7 kidney transplant recipients who received rATG as induction therapy. We tracked the evolution of the donor-reactive CD4+ and CD8+ T cell repertoires and identified stimulated pretransplant, CTV-(surface dye)-labeled, peripheral blood mononuclear cells from each patient with donor cells or third-party cells. Our analyses showed that while rATG depleted CD4+ T cells in all tested subjects, a subset of donor-reactive CD8+ T cells that were present at high frequencies pretransplant, consistent with expanded memory cells, resisted rATG depletion, underwent posttransplant expansion and were functional. Together, our data support the conclusion that a subset of human memory CD8+ T cells specifically reactive to donor antigens expand in vivo despite induction therapy with rATG and thus have the potential to mediate allograft damage.

In Vivo Effects of Porcine and Rabbit Antithymocyte Globulin in Patients with Severe Aplastic Anemia

Background: Severeaplastic anemia (SAA) is a bone marrow failure disorder mediated by T lymphocytes, resulting in severe deficiency of hematopoietic stem cells. Horse antithymocyte globulin (H-ATG) plus cyclosporin was the first-line therapy for SAA patients in the absence of an HLA-matched sibling 1. The inhibitory effect of Rabbit-ATG (R-ATG) on lymphocytes is more deeply than that of H-ATG, and the recovery of CD4 T cells is slower, resulting in poor efficacy in SAA patients 2. Porcine ATG (P-ATG) and R-ATG are two available immunosuppressive choices in China mainland, the first-line formulation of ATG remains unknown. Methods: From November 2020 through September 2022, we performed a prospective, multi-center, non-randomized trial comparing two ATG formulations. 15 patients received R-ATG therapy and 45 patients treated with P-ATG were collected by prospective registration (ChiCTR2200055696) in the Chinese Eastern Collaboration Group of Anemia (CECGA). The pharmacokinetics, dynamic changes of peripheral blood cells were evaluated. Hematologic responses were also evaluated at 3, 6 months after treatment. Results: In both P-ATG-treated and R-ATG-treated patients, ATG reached highest concentration 5 days after treatment (1268.4 ± 381.1 ug/ml and 641.2 ± 448.5 ug/ml for P-ATG and R-ATG, respectively), and gradually decreased. At week 2, week 3 and 1 month from the peak values when be assessed, the P-ATG concentration decreased by 70.3%, 81.7%, and 85.4%, while the R-ATG concentration decreased by 68.9%, 88.5%, and 92.2%, respectively. R-ATG showed more powerful effects in depleting peripheral blood lymphocytes than P-ATG, while P-ATG displayed rapid recovery of T cells (CD3 + T cells, CD4 + T cells and CD8 + T cells) (P-ATG vs R-ATG, CD3 + T cells: 30.18 ± 6.04% vs 0.49 ± 0.37%, p=0.0036; 60.58 ± 8.02% vs 7.16 ± 7.16%, p=0.0016; 77.83 ± 3.17% vs 59.67 ± 7.93%, p= 0.015 for day 3, week 1 and week 3, respectively; CD4 + T cells: 9.13 ± 2.20% vs 0.03 ± 0.02%, p=0.013, 24.49 ± 4.21% vs 1.75 ± 1.75%, p=0.0076; 38.49 ± 3.02% vs 17.62 ± 3.79%, p=0.0007 for day 3, week 1 and week 3, respectively; CD8 + T cells: 16.77 ± 4.15 vs 0.10 ± 0.067, p=0.015; 27.55 ± 3.56% vs 4.94 ± 4.94%, p=0.0036; 33.80 ± 2.19% vs 35.67 ± 6.20, p=0.72 for day 3, week 1 and week 3, respectively). There were lower number of neutrophils in patients treated with R-ATG than those treated with P-ATG during the first week after immunosuppressive therapy (P-ATG vs R-ATG, Day 3: 3.46 ± 0.49 vs 1.29 ± 0.56, p=0.02; Day 5: 3.73 ± 0.56 vs 1.12 ± 0.55, p=0.02). The overall response rates were comparable between P-ATG and R-ATG at third month and sixth month (60% vs 40%, p=0.24; 60% vs 60%, p=1). Early infection rates (within 1 month) showed no significant differences in two formulations (P-ATG vs R-ATG, 33.33% vs 46.67%, p=0.76). There were five deaths in patients treated with P-ATG and three deaths in R-ATG-treated patients (P-ATG vs R-ATG, 11.1% vs 20.0%, p=0.40). Conclusion: P-ATG and R-ATG showed different pharmacokinetics and effects on neutrophils, lymphocyte subsets, which may lead to diverse immunosuppression. These two kinds of globulins showed comparable overall response rate after treatment. Reference 1. Scheinberg P, Nunez O, Weinstein B, et al. Horse versus rabbit antithymocyte globulin in acquired aplastic anemia. N Engl J Med. 2011;365(5):430-438. 2. Feng X, Scheinberg P, Biancotto A, et al. In vivo effects of horse and rabbit antithymocyte globulin in patients with severe aplastic anemia. Haematologica. 2014;99(9):1433-1440.