Severe Graft-versus-host Disease Research Articles

Role of Defibrotide in the Prevention of Murine Model Graft-versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Vascular endothelial cells are entirely exposed and damaged during the pathogenesis of acute GVHD. Defibrotide is a mixture of single-stranded oligonucleotides that has several pharmacological effects that contribute to its endothelial protective properties. B10.BR mice were conditioned followed by the infusion of donor C57BL/6J T-cell depleted (TCD) bone marrow cells with or without splenocytes. Animals were either treated with defibrotide or appropriate controls daily for the first week and then three times per week thereafter. Allogeneic defibrotide-treated recipients demonstrated significantly better survival with reduced clinical GVHD. Significantly reduced organ pathology in the gut was associated with significantly decreased T-cell infiltration in the ileum and colon on day +28. Serum cytokine analysis revealed significantly reduced level of TNF and IL-6 at day +7 and TNF at day +28 in allogeneic defibrotide treated recipients. Significantly reduced levels of ICAM-1, Angiopoietin-2 in serum and reduced VCAM-1 and HCAM in the ileum and colon of allogeneic defibrotide-treated recipients were observed. Improved survival was seen in the GVL model (C3H.SW into C57BL/6J mice with C1498-luc). Defibrotide treatment through its anti-inflammatory and endothelial-protective effects reduces the severity of acute GVHD, while not impairing GVL activity.

Dynamics of polyclonal immuno-reconstitution after allogeneic transplant with post-transplant cyclophosphamide and letermovir.

Cytomegalovirus (CMV) reactivations are strong stimulators of immune-reconstitution (IR) in hematopoietic stem cell transplantation (HSCT) recipients. Herein, we analyzed 317 CMV-seropositive consecutive patients (n = 109 letermovir, LTV; n = 208 no-LTV), undergoing HSCT with post-transplant cyclophosphamide (PTCy) and calcineurin inhibitor- (CNI) free graft-versus-host-disease (GvHD) prophylaxis. At day+90, median CD19+/mm3 was higher in LTV-cohort: 5.5 [0;439] versus 2 [0;294], p = 0.008; median CD3+/mm3 counts were lower in LTV-cohort, with no differences in CD4+, CD8+ and NK-cells. At day+180 median CD3+, CD4+ and CD8+/mm3 values were comparable between groups. Higher CD19+/mm3 counts were observed in LTV-cohort: 62 [0; 2983] versus 42 [0; 863]. Significantly higher median NK/mm3 values were seen in LTV-cohort: 225.5 [0;763] versus 163.5 [0;1181], p = 0.0003. The impact of LTV on B-cell IR at 3 months and NK-cell levels at 6 months was retained in multivariate analysis (p < 0.01), whereas the effect on T-cells was not confirmed. Moreover, we confirmed a significant reduction of clinically-relevant CMV, and moderate-to- severe chronic GvHD in LTV-cohort. Overall, in our study the use of LTV was associated with a slight improvement of B-cell and NK-cells reconstitution, with only minor impact on T-cell subsets, giving new insights on polyclonal IR for HSCT recipients in the LTV era.

Nutritional interventions in patients with graft-versus-host.

This review aims to highlight the benefits of nutrition before and during graft-versus-host disease (GvHD) and the promising precision medicine approach that should be offered to prevent and mitigate GvHD. The intestinal damage induced by preconditioning/conditioning chemotherapies is the main trigger of GvHD. Impaired nutritional status and decreased plasma citrulline level, which is the most sensitive biomarker of intestinal barrier health, predict the occurrence of acute GvHD after allogeneic hematopoietic cell transplantation (allo-HCT). Optimal oral and/or enteral nutrition and a lack of vitamin D deficiency limit this intestinal damage. As intestinal dysbiosis plays an important role in GvHD, probiotics and prebiotics supplementation could be a promising therapy. Diverting enterostomy combined with parenteral nutrition saves the lives of patients with severe steroid-refractory gastrointestinal GvHD. Regardless of age, healthy nutritional status and a healthy gut barrier are protective factors against GvHD in patients undergoing allo-HCT, and above all, these are closely dependent on adequate oral and/or enteral intake. Therefore, maintaining gut barrier integrity through adequate oral nutrition before allo-SCT and early first-line enteral nutrition after allo-HCT are of critical importance, not forgetting vitamin D supplementation. In the future, probiotics and prebiotics are expected to play a growing role for replenishing the commensal microbiota given the impact of gut dysbiosis on GvHD. Parenteral nutrition remains the only nutritional support that can be used in the event of severe gastrointestinal GvHD.

BI07 Outcomes of oral squamous cell carcinoma following haematopoietic stem cell transplantation

Abstract Haematopoietic stem cell transplant (HSCT) recipients are at increased risk of malignancies, including cancers of the oral cavity, with a reported observed-to-expected ratio of 10.7, accounting for 14% of all solid tumours following HSCT. We report 10 cases of oral squamous cell carcinoma (SCC; 2016–2022) in HSCT recipients from a single tertiary centre [nine men and one woman; median age at diagnosis 52 years (range 27–66)]. Thirty per cent were ex-smokers and 10% current smokers. Prior to HSCT, 50% had reduced intensity conditioning, 40% had myeloablative conditioning and 10% had both. Eighty per cent were recipients of sibling allografts and 20% were recipients from matched unrelated donors. Ninety per cent had a history of chronic graft-versus-host disease (GVHD), with affected sites including the mouth (n = 6), skin (n = 6), eyes (n = 5), lungs (n = 4), kidneys (n = 3) and liver (n = 1). Forty per cent had active severe manifestations of oral GVHD. Treatments used for oral GVHD included topical immunosuppression (n = 5), oral immunosuppression (n = 6) and extracorporeal photopheresis (ECP; n = 2). Median latency from HSCT to oral SCC diagnosis was 10 years (range 4–22). At the time of SCC diagnosis, 20% were not taking immunosuppressants, 20% were being treated with topical corticosteroids and 50% with oral immunosuppression, and one patient was recently treated with ECP. Examination findings at SCC diagnosis included induration, ulceration, tenderness, bleeding, hyperkeratosis, speckling and lymphadenopathy (n = 1). Fifty per cent were asymptomatic. In 40% of cases, a previous biopsy showed hyperplastic or dysplastic changes. The commonest sites of SCC were the tongue (n = 4) and buccal mucosa (n = 3). The disease stage (TNM) at presentation ranged from T1N0M0 to T4N2M0. Sixty per cent of cases were T3 or T4 and 40% had nodal involvement. Management included radical surgical resection in 90% of cases; 10% received adjuvant radiotherapy and 10% chemoradiotherapy. One patient with an SCC on the lower lip underwent resection using Mohs micrographic surgery. Median duration of follow-up for the cohort was 0.8 years (range 0.4–5.7) with a 50% mortality rate. In our cohort, median survival following oral SCC diagnosis was 0.8 years (range 0.4–5.0) and SCC-specific mortality was 30% (n = 3). We report the largest UK case series, to the best of our knowledge, of oral SCC post-HSCT. The data show a long latency from HSCT to the onset of oral SCC, highlighting the importance of regular, active oral surveillance by haematologists, dermatologists, oral specialists and dentists. This follow-up is recommended irrespective of the severity of GVHD and length of iatrogenic immunosuppression. Intensive surveillance is indicated in groups at higher risk with a history of chronic oral GVHD.

Precision Delivery of Steroids as a Rescue Therapy for Gastrointestinal Graft-versus-Host Disease in Pediatric Stem Cell Transplant Recipients

Graft versus host disease (GVHD) is one of the most serious complications following stem cell transplant in children and is a major cause of morbidity and mortality. Corticosteroids remain the mainstay of treatment, and although a majority of children respond to systemic steroids, those refractory to or dependent upon corticosteroids suffer from complications secondary to long-term steroid administration. This problem has prompted consideration of steroid-sparing treatment strategies, although the time to clinical remission can be variable. Intraarterial corticosteroid delivery has been used in adults as a rescue therapy in steroid-resistant patients, but its use in children has been limited. We investigated the feasibility of intraarterial steroid administration into the bowel and/or liver in a cohort of six pediatric patients with acute GVHD. All patients successfully underwent treatment with no serious adverse effects. Five of five (100%) patients with gastrointestinal bleeding due to GVHD had rapid symptom improvement by 48 h, which was durable up to three weeks. Three of four (75%) patients with hepatic GVHD had improved cholestasis following intraarterial steroid administration. Our experience with this small cohort preliminarily demonstrated the feasibility and safety of intraarterial steroid administration in children with acute GVHD. This approach warrants consideration as a rescue therapy in steroid-refractory cases and as a “bridge” therapy for children with severe acute GVHD who are transitioning to steroid-sparing regimens.

Post-Transplantation Cyclophosphamide-Based Graft-versus-Host Disease Prophylaxis

BackgroundIn patients undergoing allogeneic hematopoietic stem-cell transplantation (HSCT), a calcineurin inhibitor plus methotrexate has been a standard prophylaxis against graft-versus-host disease (GVHD). A phase 2 study indicated the potential superiority of a post-transplantation regimen of cyclophosphamide, tacrolimus, and mycophenolate mofetil.MethodsIn a phase 3 trial, we randomly assigned adults with hematologic cancers in a 1:1 ratio to receive cyclophosphamide–tacrolimus–mycophenolate mofetil (experimental prophylaxis) or tacrolimus–methotrexate (standard prophylaxis). The patients underwent HSCT from an HLA-matched related donor or a matched or 7/8 mismatched (i.e., mismatched at only one of the HLA-A, HLA-B, HLA-C, and HLA-DRB1 loci) unrelated donor, after reduced-intensity conditioning. The primary end point was GVHD-free, relapse-free survival at 1 year, assessed in a time-to-event analysis, with events defined as grade III or IV acute GVHD, chronic GVHD warranting systemic immunosuppression, disease relapse or progression, and death from any cause.ResultsIn a multivariate Cox regression analysis, GVHD-free, relapse-free survival was significantly more common among the 214 patients in the experimental-prophylaxis group than among the 217 patients in the standard-prophylaxis group (hazard ratio for grade III or IV acute GVHD, chronic GVHD, disease relapse or progression, or death, 0.64; 95% confidence interval [CI], 0.49 to 0.83; P=0.001). At 1 year, the adjusted GVHD-free, relapse-free survival was 52.7% (95% CI, 45.8 to 59.2) with experimental prophylaxis and 34.9% (95% CI, 28.6 to 41.3) with standard prophylaxis. Patients in the experimental-prophylaxis group appeared to have less severe acute or chronic GVHD and a higher incidence of immunosuppression-free survival at 1 year. Overall and disease-free survival, relapse, transplantation-related death, and engraftment did not differ substantially between the groups.ConclusionsAmong patients undergoing allogeneic HLA-matched HSCT with reduced-intensity conditioning, GVHD-free, relapse-free survival at 1 year was significantly more common among those who received cyclophosphamide–tacrolimus–mycophenolate mofetil than among those who received tacrolimus–methotrexate. (Funded by the National Heart, Lung, and Blood Institute and others; BMT CTN 1703 ClinicalTrials.gov number, NCT03959241.)

Second allogeneic hematopoietic stem cell transplantation with reduced-intensity conditioning and donor changes in relapsed hematological malignancies after the first allogeneic transplant

Objective: The purpose of this study was to assess the safety and efficacy of a second allogeneic hematopoietic stem cell transplantation (allo-HSCT) with reduced-intensity conditioning (RIC) in patients with hematological malignancies who had relapsed after the first allo-HSCT. Methods: Between April 2018 and June 2021, 44 patients with hematological malignancies (B-ALL 23, T-ALL/T-LBL 4, AML15, and MDS 2) were enrolled and retrospectively examined. Unrelated donors (n=12) or haploidentical donors (n=32) were used. Donors were replaced in all patients for the second allo-HSCT. Hematological and immunological germline predisposition genes and hematopoietic and immune function tests were used to select the best-related donor. Total body irradiation (TBI) /fludarabine (FLU) -based (n=38), busulfan (BU) /FLU-based (n=4), total marrow irradiation (TMI) /FLU-based (n=1), and BU/cladribine-based (n=1) were the RIC regimens used. For graft versus host disease (GVHD) prevention, cyclosporine, mycophenolate mofetil, short-term methotrexate, and ATG were used. Eighteen (40.9%) of 44 patients with gene variations for which targeted medications are available underwent post-transplant maintenance therapy. Results: The median age was 25 years old (range: 7-55). The median interval between the first and second HSCT was 19.5 months (range: 6-77). Before the second allo-HSCT, 33 (75%) of the patients were in complete remission (CR), whereas 11 (25%) were not. All patients had long-term engraftment. The grade Ⅱ-Ⅳ GVHD and severe acute GVHD rates were 20.5% and 9.1%, respectively. Chronic GVHD was found in 20.5% of limited patterns and 22.7% of severe patterns. CMV and EBV reactivation rates were 29.5% and 6.8%, respectively. Hemorrhage cystitis occurred in 15.9% of cases, grade Ⅰ or Ⅱ. The 1-yr disease-free survival (DFS), overall survival (OS), and cumulative recurrence incidence (RI) rates of all patients were 72.5% (95% CI, 54.5%-84.3%), 80.6% (95% CI, 63.4%-90.3%), and 25.1% (95% CI, 13.7%-43.2%), respectively, with a median follow-up of 14 (2-39) months. There were eight deaths (seven relapses and one infection). The rate of non-relapse mortality (NRM) was only 2.3%. The CR patients' 1-yr RI rate was significantly lower than the NR patients (16.8% vs 48.1%, P=0.026). The DFS rate in CR patients was greater than in NR patients, although there was no statistical difference (79.9% vs 51.9%, P=0.072). Univariate analysis revealed that CR before the second allo-HSCT was an important prognostic factor. Conclusion: With our RIC regimens, donor change, and post-transplant maintenance therapy, the second allo-HSCT in relapsed hematological malignancies after the first allo-HSCT is a safe and effective treatment with high OS and DFS and low NRM and relapse rate. The most important factor influencing the prognosis of the second allo-HSCT is the patient's illness condition before the transplant.

Survival and late mortality among patients who survived disease-free for 2 years after stem cell transplantation.

Most events that limit life expectancy after allogeneic haematopoietic stem cell transplantation (allo-HSCT) occur within the first 2 years; however, treatment outcomes in long-term survivors who survive for at least 2 years post-HSCT without relapse are yet to be elucidated. To explore the life expectancy trends and late complications and to assess the main mortality-related factors, we investigated the characteristics of patients who received allo-HSCT for haematological malignancies from 2007 to 2019 in our centre and survived in remission for 2 years. A cohort of 831 patients was enrolled; of these, 508 received grafts from haploidentical-related donors (61.1%). The estimated overall survival rate at 10 years was 91.9% (95% confidence interval [CI], 89.8-93.5), which was affected by prior grade III-IV acute graft-versus-host disease (GVHD) (hazard ratio [HR], 2.98; 95% CI, 1.47-6.03; p = 0.002) and severe chronic GVHD (HR, 3.60; 95% CI, 1.93-6.71; p < 0.001). The probability of late relapse and non-relapse mortality at 10 years was 8.7% (95% CI, 6.9-10.8) and 3.6% (95% CI, 2.5-5.1) respectively. The top cause of late mortality was relapsed (49.0%). Projected long-term survival in 2-year disease-free survivors following allo-HSCT was excellent. Strategies should be implemented to minimise the late death-specific hazards in recipients.

Phase II Study of Myeloablative 7-8/8-Matched Allotransplantation with Post-Transplantation Cyclophosphamide, Tacrolimus, and Mycophenolate Mofetil

Graft-versus-host disease (GVHD) is the major toxicity of allogeneic hematopoietic cell transplantation (HCT). We hypothesized that a GVHD prophylaxis regimen of post-transplantation cyclophosphamide (PTCy), tacrolimus (Tac), and mycophenolate mofetil (MMF) would be associated with incidences of acute and chronic GVHD in patients receiving a matched or single antigen mismatched HCT. This Phase II study was conducted at the University of Minnesota using a myeloablative regimen of either total body irradiation (TBI) at a total dose of 1320 cGy, administered in 165-cGy fractions, twice daily from day -4 to day -1, or busulfan (Bu) 3.2 mg/kg daily (cumulative area under the curve, 19,000 to 21,000 μmol/min/L) plus fludarabine (Flu) 40 mg/m2 once daily on days -5 to -2, followed by a GVHD prophylaxis regimen of PTCy 50 mg/kg on days +3 and +4, Tac, and MMF beginning on day +5. The primary endpoint was the cumulative incidence of chronic GVHD necessitating systemic immunosuppression (IST) at 1 year post-transplantation. Between March 2018 and May 2022, we enrolled 125 pediatric and adult patients, with a median follow-up of 813 days. The incidence of chronic GVHD necessitating systemic IST at 1 year was 5.5%. The rate of grade II-IV acute GVHD was 17.1%, and that of grade III-IV acute GVHD was 5.5%. Two-year overall survival was 73.7%, and 2-year graft-versus-host disease-free, relapse-free survival was 52.2%. The 2-year cumulative incidence of nonrelapse mortality was 10.2%, and the rate of relapse was 39.1%. There was no statistically significant difference in survival outcomes between recipients of matched donor transplants versus recipients of 7/8 matched donor transplants. Our data show that myeloablative HCT with PTCy/Tac/MMF results in an extremely low incidence of severe acute and chronic GVHD in well-matched allogeneic HCT.

From support to therapy: rethinking the role of nutrition in acute graft-versus-host disease.

Allogeneic Hematopoietic stem cell transplantation (HSCT) offers a potential cure for patients with hematologic malignancies. Unfortunately, graft-versus-host disease (GVHD) remains a major obstacle to the greater success of this treatment. Despite intensive research efforts over the past several decades, GVHD is still a major cause of morbidity and mortality in patients receiving allogeneic HSCT. The genetic disparity between donor and recipient is the primary factor that dictates the extent of alloimmune response and the severity of acute GVHD (aGVHD). However, some nongenetic factors are also actively involved in GVHD pathogenesis. Thus, identifying host factors that can be readily modified to reduce GVHD risk is of important clinical significance. We are particularly interested in the potential role of nutrition, as a nongenetic factor, in the etiology and management of aGVHD. In this article, we summarize recent findings regarding how different routes of nutritional support and various dietary factors affect aGVHD. Since diet is one of the most important factors that shape gut microbiota, we also provide evidence for a potential link between certain nutrients and gut microbiota in recipients of allogeneic HSCT. We propose a shifting role of nutrition from support to therapy in GVHD by targeting gut microbiota.

Efficacy of CLAE Chemotherapy Regimen Followed by Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Relapsed/Refractory Acute Leukemia

To observe the efficacy and safety of CLAE intensive chemotherapy followed by allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with relapsed/refractory acute leukemia (R/R AL). CLAE regimen [cladribine 5 mg/(m2·d), d 1-5; cytarabine 1.5 g/(m2·d), d 1-5; etoposide 100 mg/(m2·d), d 3-5] followed by allo-HSCT was used to treat 3 R/R AL patients. The patients received CLAE chemotherapy in relapsed or refractory status and underwent bone marrow puncture to judge myelodysplastic state. After an interval of 3 to 5 days, followed by preconditioning regimen for allo-HSCT [fludarabine 30 mg/(m2·d), d -7 to d -3; busulfan 0.8 mg/kg q6h, d -6 to d -3 or d -5 to d -2. If the bone marrow hyperplasia was not active and the blasts were less than 10%, busulfan should be used for 3 days. If the bone marrow hyperplasia was active and the blasts were more than 10%, busulfan should be used for 4 days]. Cyclosporin A, mycophenolate mofetil and short-term methotrexate were used for graft-versus-host disease (GVHD) prevention. After transplantation, the status of minimal residual disease (MRD) and bone marrow chimerism were regularly monitored in all 3 patients, and demethylation drugs or dasatinib were used to prevent recurrence 3 months after transplantation. 2 patients with t(11;19) translocation and relapse/refractory acute myeloid leukemia recurred within 6 months after induction of remission, and received intensive chemotherapy with CLAE regimen followed by haploidentical allo-HSCT and unrelated donor allo-HSCT, respectively. The two patients both relapsed 6 months after transplantation, then achieved complete remission by donor lymphocyte infusion, interferon, interleukin-2 and other methods, and disease-free survival was 2 years after transplantation. The other patient was chronic myelogenous leukemia who developed acute lymphoblastic leukemia during oral administration of tyrosine kinase inhibitor, accompanied by T315I and E255K mutations in ABL1 kinase region and additional chromosomal abnormalities. After morphological remission by induction chemotherapy, central nervous system leukemia was complicated. Intensive chemotherapy with CLAE regimen followed by sibling allo-HSCT was performed in the positive state of MRD. The patient relapsed 3 months after transplantation, and achieved remission after chimeric antigen receptor T-cell (CAR-T) therapy, however, he died 5 months after transplantation because of severe cytokine release syndrome (CRS) and GVHD. CLAE regimen followed by allo-HSCT may be an effective salvage treatment option for R/R AL patients to prolong the overall survival.

Early in vivo generation of Vγ9Vδ2 T-cells after haploidentical stem cell transplant with post-transplant cyclophosphamide: Updated results of a monocentric phase 1 study.

7050 Background: The presence of donor Vγ9Vδ2 T-cells after haploidentical hematopoietic stem cell transplant (haplo-HSCT) has been associated with improved disease-free survival. These cells, that kill tumor cells in a non-MHC restricted manner and do not induce graft-versus-host disease (GVHD) can be generated by stimulation with bisphosphonate zoledronic acid (ZA), in combination with interleukin-2 (IL-2). Methods: A prospective monocentric phase 1 dose-escalating study aimed at demonstrating the possibility to generate Vγ9Vδ2 T-cells in vivo after haplo-HSCT with post-transplant cyclophosphamide (PTCY). A 3x3 protocol was designed to determine the maximum tolerated dose (MTD) of early administration of increasing low-doses of IL-2 in combination with a fixed dose of ZA, starting the first Monday after day+15 post-transplant. A single dose of 4 mg IV ZA was administered, followed, by subcutaneous injections of IL-2, 5 days/week, for 4 consecutive weeks. Three IL-2 doses were tested: 2, 4 and 6 million UI/infusion. Main inclusion criteria were patients (pts) between 18-70 years old with a hematological disease eligible for haplo-SCT using a Baltimore-based conditioning, no HLA-matched sibling or unrelated donor, no contra-indication to ZA nor IL-2 and informed consent. MTD was defined by the dose just below that which yielded 2/3 or 2/6 dose limiting toxicities (DLT), including severe or recurrent acute GVHD. Vγ9Vδ2 T-cells monitoring was performed in multiparameter flow cytometry on blood samples collected before conditioning, on the day of the first ZA and IL-2 injection, once a week+-3 for 4 weeks and at day +70 post-graft. The protocol was registered at ClinicalTrials.gov as NCT03862833. Results: Twenty-six pts were included between April 2019 and September 2022 (including 7 controls). Three pts withdraw their consents in the experimental group, and 16 pts were treated with ZA and IL-2 (level 1 n = 7 including 1 not evaluable for DLT, level 2 n = 3, level 3 n = 6). First injections occurred at a median of 20 days after Day 0 (range: 17-21). One, 0 and 1 DLT and 4, 2, 2 acute GVHD (all grade II-III) were documented, and MTD was not reached. Vγ9Vδ2 T cells were clearly detectable in both controls and treated pts before conditioning. The median highest value (0.6x106/L, range: 0.0-3.2) was observed at a median of 12 days (8-12) after first infusion of ZA+IL-2. A significantly higher proportion of Vγ9Vδ2 T cells was observed at days +22 and +29 in treated pts compared to controls. At the date of the submission, 3 relapse/progression occurred in treated pts, and 10 are alive in CR. Median OS is not reached. Conclusions: Early in vivo generation of Vγ9Vδ2 T cells is possible after haplo-SCT with PTCY by using a combination of ZA and repeated IL-2 infusions. The DMT has not been reached. This study lays the groundwork for future phase 2/3 studies. Clinical trial information: NCT03862833 .

Acute Graft-versus-Host Disease: An Update on New Treatment Options.

Acute graft-versus-host disease (GVHD) occurs in approximately 50% of patients and remains a primary driver of non-relapse and transplant-related mortality. The best treatment remains prevention with either in vivo or ex vivo T-cell depletion, with multiple strategies used worldwide based on factors such as institution preference, ability to perform graft manipulation, and ongoing clinical trials. Predicting patients at high risk for developing severe acute GVHD based on clinical and biomarker-based criteria allows for escalation or potential de-escalation of therapy. Modern therapies for treatment of the disease include JAK/STAT pathway inhibitors, which are standard of care in the second-line setting and are being investigated for upfront management of non-severe risk based on biomarkers. Salvage therapies beyond the second-line remain suboptimal. In this review, we will focus on the most clinically used GVHD prevention and treatment strategies, including the accumulating data on JAK inhibitors in both settings.

A prospective phase 2 clinical trial of a C5a complement inhibitor for acute GVHD with lower GI tract involvement.

Involvement of lower gastrointestinal tract (LGI) occurs in 60% of patients with graft-versus-host-disease (GVHD). Complement components C3 and C5 are involved in GVHD pathogenesis. In this phase 2a study, we evaluated the safety and efficacy of ALXN1007, a monoclonal antibody against C5a, in patients with newly diagnosed LGI acute GVHD receiving concomitant corticosteroid. Twenty-five patients were enrolled; one was excluded from the efficacy analysis based upon negative biopsy. Most patients (16/25, 64%) had acute leukemia; 52% (13/25) had an HLA-matched unrelated donor; and 68% (17/25) received myeloablative conditioning. Half the patients (12/24) had a high biomarker profile,Ann Arbor score 3; 42% (10/24) had high-risk GVHD per Minnesota classification. Day-28 overall response was 58% (13/24 complete response, 1/24 partial response), and 63% by Day-56 (all complete responses). Day-28 overall response was 50% (5/10) in Minnesota high-risk and 42% (5/12) in high-risk Ann Arbor patients, increasing to 58% (7/12) by Day-56. Non-relapse mortality at 6-months was 24% (95% CI 11-53). The most common treatment-related adverse event was infection (6/25, 24%). Neither baseline complement levels (except for C5), activity, nor inhibition of C5a with ALXN1007 correlated with GVHD severity or responses. Further studies are needed to evaluate the role of complement inhibition in GVHD treatment.

Abatacept GVHD prophylaxis in unrelated hematopoietic cell transplantation for pediatric bone marrow failure.

Hematopoietic cell transplantation (HCT) is the only readily available cure for many life-threatening pediatric nonmalignant diseases (NMD), but most patients lack a matched related donor and are at higher risk for graft-versus-host disease (GVHD). Use of abatacept (Aba) to target donor T-cell activation has been safe and effective in preventing GVHD after unrelated donor (URD) HCT for malignant diseases (Aba2 trial). Our primary objective wasto evaluate the tolerability of Aba added to standard GVHD prophylaxis (cyclosporine and mycophenolate mofetil) in pediatric patients with NMD undergoing URD HCT. In this single-arm, single-center phase 1 trial, 10 patients receiving reduced intensity or nonmyeloablative conditioning underwent URD HCT. Immune reconstitution was assessed longitudinally via flow cytometry and compared to pediatric patients on Aba2. Nine patients successfully engrafted, with 1 primary graft rejection in the setting of inadequate cell dose; secondary graft rejection occurred in 1 patient with concurrent cytomegalovirus viremia. Two deaths occurred, both unrelated to Aba. One patient developed probable posttransplant lymphoproliferative disease, responsive to rituximab and immune suppression withdrawal. No patients developed severe acute or chronic GVHD, and 8 patients were off systemic immunosuppression at 1 year. Immune reconstitution did not appear to be impacted by Aba, and preservation of naïve relative to effector memory CD4+ T cells was seen akin to Aba2. Thus, 4 doses of Aba were deemed tolerable in pediatric patients with NMD following URD HCT, with encouraging preliminary efficacy and supportive immune correlatives in this NMD cohort.

Round-Robin test for the histological diagnosis of acute colonic Graft-versus-Host disease validating established histological criteria and grading systems

Histomorpholgy is one of the mainstays of acute Graft-versus-host disease (GvHD) diagnosis. However, concerns about reproducibility and the most appropriate grading system question its usefulness. Our aim was to assess histomorphological parameters and previously reported grading systems for GvHD regarding reproducibility and validity. Moreover, we propose that sum scores, derived by combining separately scored morphological parameters into a total score, might provide a simplified but equally effective means to grade GvHD. A total of 123 colon biopsies were assessed across four pathologists for intestinal GvHD using a Round-Robin test and results were correlated with clinical findings. Interobserver reproducibility was high for histological parameters that were evaluated as indicators of acute GvHD. Published grading systems were moderately reproducible (ICC 0.679–0.769) while simplified sum scores, in comparison, showed better interrater reliability (ICC 0.818–0.896). All grading systems and sum scores were associated with clinical signs of GvHD and in part with therapy response and survival. However, they were not able to stratify patients according to the clinical severity of GvHD. In a hot-spot analysis 1 crypt apoptotic body (CAB) in 10 crypts was a reasonable cut-off value for minimal diagnostic criteria of GvHD. In conclusion, histology can contribute to the diagnosis of GvHD and is reproducible. Published grading systems are able to reflect clinical findings as are simplified sum scores, which showed improved reproducibility and might be easier to handle as they are based on adding up histological parameters rather than transferring histological findings into a separate grading system. Sum scores will have to be further tested in a prospective setting.

Shared graft-versus-leukemia minor histocompatibility antigens inDISCOVeRY-BMT.

T-cell responses to minor histocompatibility antigens (mHAs) mediate graft-versus-leukemia (GVL) effects and graft-versus-host disease (GVHD) in allogeneic hematopoietic cell transplantation. Therapies that boost T-cell responses improve allogeneic hematopoietic cell transplant (alloHCT) efficacy but are limited by concurrent increases in the incidence and severity of GVHD. mHAs with expression restricted to hematopoietic tissue (GVL mHAs) are attractive targets for driving GVL without causing GVHD. Prior work to identify mHAs has focused on a small set of mHAs or population-level single-nucleotide polymorphism-association studies. We report the discovery of a large set of novel GVL mHAs based on predicted immunogenicity, tissue expression, and degree of sharing among donor-recipient pairs (DRPs) in the DISCOVeRY-BMT data set of 3231 alloHCT DRPs. The total number of predicted mHAs varied by HLA allele, and the total number and number of each class of mHA significantly differed by recipient genomic ancestry group. From the pool of predicted mHAs, we identified the smallest sets of GVL mHAs needed to cover 100% of DRPs with a given HLA allele. We used mass spectrometry to search for high-population frequency mHAs for 3 common HLA alleles. We validated 24 predicted novel GVL mHAs that are found cumulatively within 98.8%, 60.7%, and 78.9% of DRPs within DISCOVeRY-BMT that express HLA-A∗02:01, HLA-B∗35:01, and HLA-C∗07:02, respectively. We confirmed the immunogenicity of an example novel mHA via T-cell coculture with peptide-pulsed dendritic cells. This work demonstrates that the identification of shared mHAs is a feasible and promising technique for expanding mHA-targeting immunotherapeutics.

Sequence matters: Total body irradiation (TBI)-based myeloablative conditioning with post-transplant cyclophosphamide may reduce the early nonrelapse mortality compared with pretransplant cyclophosphamide plus TBI.

High-dose total body irradiation (TBI) is considered a cornerstone of myeloablative conditioning for allogeneic stem cell transplantation (allo-SCT). We retrospectively compared the main outcomes of an HLA matched or 1-allele mismatched related or unrelated allo-SCT in adult patients affected by acute leukemia (AL) or myelodysplastic syndromes (MDS). Fifty-nine patients received cyclophosphamide (Cy)-TBI (13.5 Gy) and graft-versus-host disease (GVHD) prophylaxis with a calcineurin-inhibitor plus methrotrexate (CyTBI group) and 28 patients received fludarabine-TBI (8.8-13.5 Gy) and GVHD prophylaxis with PTCy and tacrolimus (FluTBI-PTCy group). Median follow-up for survivors was 82 and 22 months. The 12-month probability of overall survival and progression-free survival were similar (p = .18, p = .7). The incidence of Grades 2-4 and 3-4 acute GVHD, and the incidence of moderate-to-severe chronic GVHD were higher in the CyTBI group (p = .02, p < .01and p = .03). Nonrelapse mortality (NRM) at 12 months posttransplant was higher in the CyTBI group (p = 0.05), while the incidence of relapse was similar in both groups (p = 0.7). The number of GVHD-free and relapse-free patients without systemic immunosuppression (GRFS) at 1-year posttransplant was higher in the FluTBI-PTCy group (p = 0.01). The study confirms the safety and efficacy of a novel FluTBI-PTCy platform with reduced incidence of severe acute and chronic GVHD, and early improvement of NRM.

Abstract 5195: BNDG B2m KO plus mouse model is a powerful tool for immunotherapy

Abstract The B-NDG (Biocyotgen; NOD; DNAPK null; IL2rg knockout) mouse model was developed to be an ideal testing platform for anti-tumor therapies in Cell-Line and Patient Derived Xenograft Models (CDX and PDX respectively). B-NDG mice exhibit several notable advantages over classical NOD-scid mice, including increased life span, NK cell deletion, and significantly improved xenograft efficiency. However, like the NOD-scid mice, the utility of B-NDG mice in long-term studies is severely limited by a high incidence of severe and early-onset GvHD (Graft versus Host Disease) - limiting experimental durations to as little as 30 days. To reduce the incidence and severity of GvHD in B-NDG mice, Biocytogen developed the B-NDG B2m KO plus mice. B-NDG B2m KO plus mice was generated using Cas9 approach. Specifically, endogenous mouse B2m was deleted, while B2m cDNA was fused with Fcgrt. MHC Class I and Class II expressions, and immune markers were verified by flow cytometry. Concentration of i.v. administered human IgG was quantified by ELISA. CDX models were generated, and antitumor therapies were administered using established protocols described below. Compared with NOD-scid and B-NDG mice, B-NDG B2m KO plus mice showed undetectable MHC Class I expression in all tested tissues, without compromising MHC Class II expression. Moreover, no significant change in immune profiles or IgG turnover was detected, demonstrating highly targeted disruption of MHC Class I expression in B-NDG B2m KO plus mice. In the human PBMC-induced GvHD model, B-NDG B2m KO plus mice showed significantly improved survival, delayed onset and reduced clinical severity throughout the course of the model. Compared with B-NDG mice, B-NDG B2m KO plus mice exhibits significantly prolonged usefulness, demonstrating utility for up to 50 days after engraftment. To demonstrate the advantages of our B-NDG B2m KO plus mouse model, we conducted two proof-of concept studies that are often limited by GvHD. In the first study, B-NDG B2m KO plus mice were engrafted with human PBMCs and tumorigenic RKO cells on Day 0 and 14 respectively, treated with either vehicle or pembrolizumab and ipilimumab on Day 20, and observed until Day 48. Pembro/ipi treatment significantly inhibited tumor growth. In the second study, B-NDG B2m KO plus mice were engrafted with tumorigenic human NCI-H226 cells on Day 0, treated with either vehicle or CAR-T cells (5E5) once tumor size reached ~150 mm3 (around Day 20), and observed until Day 56. CAR-T treatment significantly suppressed tumor growth. Together, these studies demonstrated that the B-NDG B2m KO plus mouse model is a powerful tool for extended term anti-tumor studies, especially for studies involving immuno- and CAR-T therapies. Citation Format: Hongmei Jiang, Jianqiu Xiao, Travis Rothrock. BNDG B2m KO plus mouse model is a powerful tool for immunotherapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5195.

Post-transplant cyclophosphamide as sole GHVD prophylaxis after matched reduced-intensity conditioning allotransplant.

Post-transplant cyclophosphamide (PTCY) alone as graft-versus-host disease (GVHD) prophylaxis may avoid/reduce short- and mid-term toxicities of drugs commonly used for GVHD prophylaxis, accelerate immune reconstitution after the graft to decrease infections and facilitate the early integration of adjunct maintenance therapies to prevent relapse. A prospective phase 2 study was designed in order to assess the feasibility and safety of PTCY as a sole GVHD prophylaxis in adult patients receiving a Baltimore-based reduced-intensity conditioning (RIC) peripheral blood (PB) allogeneic hematopoietic stem cell transplantation (Allo-HSCT) with a matched donor. Patients were planned to be included stepwise up to 59 evaluable PTCY recipients, in order to be able to stop the protocol in case of excessive corticosteroid resistant grade 3-4 severe acute GVHD (aGVHD). Because a high incidence of grade 2-4 aGVHD was observed after analysis of the first 27 patients, the protocol was amended to test the addition of 1 day of anti-thymoglobulin to PTCY. In spite of this, the trial had to be stopped after 38 treated patients, because of an unacceptable rate of grade 3-4 aGVHD. Donors were matched related to 12 patients and unrelated to 26. With a median follow-up of 29.6 months, 2-year overall, disease-free and GVHD-free relapse-free (GRFS) survivals were respectively 65.4%, 62.1% and 46.9%. Cumulative incidences of grade 2-4 and 3-4 aGVHD at day 100 were 52.6% and 21.1%, respectively, while that of moderate/severe chronic(c) GVHD was 15.7% at 2 years. Addition of ATG to PTCY did influence neither aGVHD, cGVHD nor GRFS. Despite paradoxically good survivals, especially GRFS, this study failed to demonstrate that PTCY (±ATG) alone can be used for Baltimore-based RIC PB Allo-HSCT with matched donors. Other combinations should be tested to try and avoid long-term use of immunosuppressive drugs following Allo-HSCT in this setting.