Skin Graft-versus-host Disease Research Articles

Autophagy differentially regulates tissue tolerance of distinct target organs in graft-versus-host disease models.

Tissue-intrinsic mechanisms that regulate severity of systemic pathogenic immune-mediated diseases, such as acute graft-versus-host disease (GVHD), remain poorly understood. Following allogeneic hematopoietic stem cell transplantation, autophagy, a cellular stress protective response, is induced in host nonhematopoietic cells. To systematically address the role of autophagy in various host nonhematopoietic tissues, both specific classical target organs of acute GVHD (intestines, liver, and skin) and organs conventionally not known to be targets of GVHD (kidneys and heart), we generated mice with organ-specific knockout of autophagy related 5 (ATG5) to specifically and exclusively inhibit autophagy in the specific organs. When compared with wild-type recipients, animals that lacked ATG5 in the gastrointestinal tract or liver showed significantly greater tissue injury and mortality, while autophagy deficiency in the skin, kidneys, or heart did not affect mortality. Treatment with the systemic autophagy inducer sirolimus only partially mitigated GVHD mortality in intestine-specific autophagy-deficient hosts. Deficiency of autophagy increased MHC class I on the target intestinal epithelial cells, resulting in greater susceptibility to damage by alloreactive T cells. Thus, autophagy is a critical cell-intrinsic protective response that promotes tissue tolerance and regulates GVHD severity.

Post-Transplant Cyclophosphamide, Abatacept, and Vedolizumab to Prevent Graft-Versus-Host Disease after Hematopoietic Stem Cells Transplantation from Haploidentical Donors in Children with Acute Leukemia: Results of a Prospective Trial

Introduction Graft-versus-host disease (GvHD) remains a crucial complication associated with significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). High-dose post-transplantation cyclophosphamide (PTCy) targets alloreactive donor T cells proliferating early after HSCT, promotes regulatory T cells, and prevents severe GVHD. The effectiveness of PTCy-based regimens varies depending on the graft source and intensity of the preparative regimen. Improvement of GVHD control with novel targeted agents, added to the backbone of PTCy, could further increase the safety of HSCT and reduce the morbidity and complications of standard regimens of pharmacological immune suppression. In this pilot trial, we evaluated the safety and efficacy of abatacept and vedolizumab in unmanipulated haploidentical transplantation among children with leukemia. Materials and methods A total of 54 pts with acute leukemia (AML- 18, ALL-36, 26 female, 28 male, the median age at HSCT - 7,4 years (0,4-16,8), underwent unmanipulated allogeneic bone marrow (BM) (n=53) or peripheral blood stem cell (PBSC)(n=1) transplantation between March 2022 and May 2023. All donors were haploidentical relatives, represented Disease status at transplant was CR1 in 25 pts, CR³2 in 29 pts. For all patients, it was the 1-st transplantation. All patients received myeloablative conditioning, either TBI-based (n=30) or 24 treosulfan-based (n=24), with either cyclophosphamide (n=47) or etoposide (n=7) as a second agent. Prophylaxis of graft-versus-host-disease (GVHD) consisted of CsA from day-1 to day 180, 50 mg/kg of Cph on days +3 and +4, abatacept at 10 mg/kg on days +5, +14, +28, +45, +60 and vedolizumab at 10 mg/kg (capped at 300 mg) on days -1, +14, +28. The median dose of CD34+ cells was 4,7 x10 6/kg (range 1,2-17), and the CD3 dose was 42 x10 6/kg. Results Primary engraftment was achieved in 53 (98%) pts; the median time to neutrophil and platelet recovery was 20 and 23 days, respectively. All engrafted pts had verified morphologic remission and achieved complete donor chimerism by day +30. One patient failed to engraft, relapsed, and required rescue with a second HSCT from an alternative donor. The regimen was generally well tolerated. Acute toxicity consisted of grade III-IV mucositis (n=5); grade II-III hemorrhagic cystitis (n=4); grade III-V veno-occlusive disease (n=2) (all cases of VOD developed after pre-HSCT use of inotozumab); bloodstream infections (n=8). Four patients were admitted to the intensive care unit due to septic events or VOD. The median follow-up time for survivors was seven months (range: 1 -15). Transplant-related mortality was 2% (95% CI:0,3-14): one patient with ALL previously treated with inotozumab died in CR due to consequences of severe VOD on day + 60. The cumulative incidence of aGVHD grade II-IV was 36% (95% CI, 25 - 52), and grade 3-4 was 9% (95% CI, 4 - 22). In 13 cases, aGVHD was limited to skin: grade 2 (n=12), grade 4 (n=1), in two cases to the gut: grade 3(n=1), grade 4(n=1), three patients had skin and gut GVHD: grade 2 (n=2), grade 3(n=1) and one had skin and liver GVHD grade 3. The cumulative incidence of gut aGVHD grade II-IV was 9% (95% CI, 4 - 22). Eleven patients with GVHD responded to first-line immunosuppressive treatment, while 8 received additional therapy. The cumulative incidence of relapse was 11% (95%CI:5-26) in the entire cohort. EFS and OS were 89% (95%CI: 79-97) and 98% (95%CI: 94-100). The GVHD- and relapse-free survival was 78% (95%CI:67-88). Conclusion Our data suggest that adding vedolizumab and abatacept to the PTCy-based GVHD prophylaxis backbone is well tolerated and may reduce the incidence of gut GVHD among children with acute leukemia grafted from haploidentical donors. This approach can be further developed to reduce exposure to calcineurin inhibitors and deploy additional anti-leukemia effectors after HSCT.

Clinical Characteristics, Management, and Allogeneic Hematopoietic Cell Transplantation of Patients with Toll-like Receptor 8 Gain-of-Function Mutations

Toll-like receptor 8 gain-of-function (TLR8 GOF) is a recently described inborn error of immunity due to germline or somatic mutations in the TLR8 gene and characterized by severe neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases, bone marrow failure. Treatment of TLR8 GOF has been challenging to date, and guidance for optimal therapy is lacking. We describe the clinical characteristics and management of 10 patients with TLR8 GOF variants, including the first female patient and further clinical outcome on the 6 patients initially reported with this disease with a focus on the role of allogeneic hematopoietic cell transplantation (HCT). All but one patient were male ranging from 0.5 months to 28 years at age of symptom onset. Eight patients had somatic mutations with variant allele frequencies of 7-26%; two patients had germline mutations. The 9 male patients all had severe neutropenia and varying degrees of anemia and/or thrombocytopenia. Oral ulcers, recurrent infections, hepatosplenomegaly, and hypogammaglobulinemia were common. Immune phenotype was variable, ranging from severe lymphopenia to marked T cell lymphoproliferation. Several patients had an inverted CD4:CD8 T cell ratio and skewing of T cell subsets to the terminal effector memory phenotype. Increased double-negative T cells were also observed. All patients had low class switched memory B cells. Bone marrows were hypo- to hypercellular with marked myeloid hypoplasia, and in most cases, with increased T cells, large granular lymphocytes, and/or lymphoid aggregates. Neutropenia was initially responsive to granulocyte colony stimulating factor (GCSF) +/- steroids in several patients but ultimately become refractory to therapy. Immunomodulatory agents and chemotherapy were unsuccessful. Six patients underwent allogeneic HCT; two patients died at 8 and 18 years without definitive therapy; and one patient was lost to follow-up. The female patient had germline disease and presented with pure red blood cell aplasia at 2 weeks of life and is scheduled to undergo HCT. Transplant data were available for 5 of 6 patients who underwent HCT. Age at transplant was 3 to 21 years. One patient who received a graft from a 7/8 HLA-matched unrelated donor developed severe veno-occlusive disease and secondary graft failure. The patient underwent a second transplant and ultimately died. Another patient received a matched sibling donor HCT while critically ill from Candida lusitaniae and mucormycosis infection with associated multisystem organ failure. The patient engrafted with 100% donor chimerism but died on day +15 post-HCT. The remaining 3 patients are alive and well 8 months to 2 years post-HCT. Two patients received grafts from HLA-matched donors (1 sibling and 1 unrelated) with reduced intensity conditioning and cyclophosphamide, mycophenolate mofetil and vorinostat for graft-versus-host disease (GVHD) prophylaxis. The third patient underwent a haploidentical HCT with myeloablative conditioning and post-transplant cyclophosphamide. Post-HCT complications included acute skin and/or gastrointestinal GVHD that was responsive to therapy in all patients, and severe lung GVHD in one patient. There were no major infectious complications. All three patients had full donor chimerism in myeloid and T cells with complete resolution of disease phenotype at last follow-up. The patient for whom detailed transplant data is not available received a haploidentical HCT. He developed mixed myeloid chimerism for which he received multiple donor lymphocyte infusions and was alive at last contact >3 years post-HCT. TLR8 GOF should be considered in male and female patients with severe, unexplained neutropenia refractory to GCSF, and particular care should be taken when investigating for mutations given the disease-causing variant allele frequencies as low as 7%. Neutropenia and immune dysregulation were refractory to all therapies in our cohort, and TLR8 GOF was fatal in two patients who did not receive definitive therapy. Allogeneic HCT is curative and should be considered without delay for medically suitable patients.

Treosulfan Based Haploidentical Αß T Cell Depleted HSCT Represents a Curative Alternative in Pediatric and Adult Patients with Transfusion Dependent Thalassaemia

Background: Quality of life remains severely compromised in patients suffering from Transfusion Dependent Thalassemia (TDT) despite optimal supportive care. HSCT with a MSD, the current curative option, achieving a 92.1% 2y-OS in children and 84.4% in adults (EBMT registry). Unfortunately, availability of MDs is limited, so that haploidentical HSCT is increasingly explored. Methods: 13 TDT patients (median age: 11 years; range: 2-23) received either a CD3 +/CD19 + (n=4; all class II/III) or αß/CD19 + (n=10; 7 class II, II/III) T-haplo-HSCT and were compared with 8 TDT-patients (7 class II, II/III, III) receiving a BM graft from a MSD (median age: 11 years; range: 4-22). Indication for T-haplo HSCT patients was severe iron overload/ transfusion-associated complications. All patients received an identical conditioning regimen consisting of treosulfan, thiotepa, fludarabine (FTT) and ATG-Grafalon, with the only difference in the timing of ATG (upfront in T-haplo-HSCT, prior to d0 in MSD-HSCT). Immunosuppression (IST) was maintained for a minimum of 180 days consisting of calcineurin inhibitors (mainly tacrolimus) and MMF. Results: The OS and DFS for MSD and T-haplo-HSCT was 100%/100% and 100%/92%, respectively (Table 1). The median follow-up was 30 months for MSD (range 4-72) and 38 months for T-haplo-HSCT (range 4-86). Neutrophil engraftment was achieved after a median of 31 days for MSD patients and 17 days for T-haplo-HSCT with a median of 5 x 10 8 TNC/kg (range: 3.28-7.88) and 15 x 10 6 CD3 +/CD19 + or αβ/CD19 + depleted CD34 + cells/kg (range: 9.2-24.2), respectively. One patient received two T-haplo HSCT, due to primary graft failure partly due to a major AB0 incompatibility. A mixed chimerism was observed in 3/7 MSD-HSCT (median 92%; range 27.5-100%) and in T-haplo-HSCT in 2/13 patients (median 99%; range: 45.3 -100%). Transfusion independence was achieved in all MSD and in all but one T-haplo patient. In MSD and in T-haplo-HSCT, IST was terminated after a median of 173 days and 226 days (range: 112-347), respectively. MSD patients reached CD4 counts >50/µl on day +43 (median; range: 25-125) and T-haplo-HSCT patients on day +114 (median; range: 33-173). The treosulfan-based conditioning regimen was well tolerated with no VOD/SOS observed in this high-risk population. No case of acute or chronic Graft-versus-Host disease (GvHD) was observed in the MSD population. In T-haplo-HSCT, 3 patients experienced grade I acute GvHD (skin) which resolved with prednisolone and in 2 cases with additional extracorporeal photopheresis. Only the oldest patient experienced mild chronic skin GvHD, which resolved by day +580. No severe infectious complications occurred despite a prolonged chimerism-triggered weaning of the IST. Conclusions: Independent of donor availability, graft rejection and iron-overload related organ damage (VOD/SOS) are major pitfalls in transplanting advanced stage TDT patients. Treosulfan demonstrated to be an excellent alternative to busulfan in this setting reflected in the safety and efficacy data of this pilot series. Overall, outcomes of T-haplo-HSCT in TDT are very encouraging with a competitive OS, so that a transplant indication in pediatric and AYA TDT patients lacking a MD is feasible.

Outcomes of Treosulfan Vs. Busulfan Based Conditioning Regimens in Adult Patients Undergoing Allogeneic HSCT: Real Life Data from a Single Center

Introduction The type of conditioning regimen has a great impact on the outcome of patients who undergo allogeneic HSCT since graft versus host disease (GVHD), infections, regimen related organ and tissue toxicities are among the most important causes of post-transplant mortality. Despite the regimen related toxicity profile of busulfan, supported by information from the results of clinical trials and real-world data, it is still commonly used worldwide. Treosulfan has advantages in terms of dose of administration, lower incidence of sinusoidal obstruction syndrome and lower neurotoxicity. We aimed to retrospectively investigate outcomes and compare results of patients who underwent matched and haploidentical allogeneic HSCT with treosulfan based or busulfan based reduced intensity conditioning, non-myeloablative conditioning and myeloablative conditioning regimens in our institution. Methods From September 2016 to November 2022, treosulfan was administered to 94 patients while 85 patients received busulfan. We analyzed outcomes as regimen related-toxicity, chronic and acute GVHD, overall survival, non-relapse mortality, relapse related mortality and fungal infection. The myeloablative dose of busulfan was 12.8 mg/kg while it was 9.6 mg/kg for the non myeloablative regimen which was combined with fludarabine. The myeloablative dose of treosulfan was 42 mg/m2 while a dose range of 30-36 mg/m2 was administered for the reduced intensity conditioning. Results The median follow up was 14 months for the treosulfan group while it was 11 months for the busulfan group (p = 0.16). Regimen related toxicity, which was monitored during the hospital stay and 3 months after discharge were 11.7% and 7.1% for treosulfan and busulfan respectively and were similar between two groups. Extensive chronic GVHD was encountered in 15.7% of the patients in the treosulfan group compared to 32.1% in the busulfan group (p < 0.001). Similarly, chronic skin GVHD was observed in 3.6% of the patients who received treosulfan while it was seen in 22.6% of the busulfan group (p < 0.001). Acute GVHD (grade 3 or higher) was encountered in 32.2% of the patients within the treosulfan group while it was encountered in 31.6% of the patients in the busulfan group. Overall survival was 47.5% and 36.5 % in the treosulfan group and busulfan groups respectively. The relapse-related mortality was 17 % in the treosulfan group while it was 34% in the busulfan group. Fungal infection was observed in 23.4% and 36.5% of the patients in treosulfan and busulfan groups respectively. Conclusion Treosulfan, with a lower chronic GVHD incidence and similar regimen related toxicity profile appears to be a safe alternative to busulfan and prospective randomized controlled trials are needed to confirm the results in our study. Keywords: Busulfan; treosulfan; conditioning regimen; stem cell transplantation

Janus Kinase (JAK) 1 Inhibition Results in Significant Changes in Serum Proteins and Peripheral T-Cell Populations That Correlated with Clinical Scores in Chronic Graft Versus Host Disease (GVHD) Patients (an Analysis from GRAVITAS-309)

Background: Chronic GVHD (cGVHD) occurs in 30-70% of allogeneic hematopoietic cell transplantation patients, and the rate has increased over the past 2 decades. Based on the degree of organ involvement, cGVHD is classified as mild, moderate, or severe. Standard treatment includes systemic corticosteroids (CS), together with immunosuppressive agents. GRAVITAS-309 (NCT03584516) was designed as a 2-part, multicenter, randomized trial to assess efficacy and safety of itacitinib, an orally bioavailable, selective JAK1 inhibitor, in combination with CS as first-line treatment for moderate to severe cGVHD. The dose-finding, open-label, randomized portion of the study initially investigated itacitinib at 200 mg once daily (qd) and 300 mg qd in combination with CS (methylprednisolone or prednisone); both doses were well tolerated. The trial was expanded to test itacitinib 400 mg qd and 300 mg twice daily (bid); the initial 300 mg qd cohort was expanded and a CS monotherapy cohort was added. Results from the expanded portion of the study (n=139 patients) showed improved overall response rate (ORR) at 6 months in patients treated with itacitinib + CS vs CS alone (Im, et al. Blood 2022;140[Suppl 1]:1870). Here, we analyzed samples collected from patients in 4 cohorts (cohort A [300 mg qd], cohort B [400 mg qd], cohort C [300 mg bid], and cohort D [CS alone]) for systemic proteins and immune cell populations, to support investigation into the itacitinib mechanism of action and to correlate with clinical outcomes. Methods: Peripheral blood mononuclear cells (PBMCs) and serum were collected before treatment (baseline, day 1), and day 7, day 14 (PBMCs only), and day 28 following treatment initiation. Serum proteins were analyzed using the OLINK Target 96 platform, and circulating T-cell subsets were measured using flow cytometry of PBMCs and presented as a percentage of parent population. Samples were assessed irrespective of patients' response. Most of the patients (70-100% per cohort) with samples available for analysis were responders (achieved complete or partial responses). Results: Serum levels of proteins, including several proposed as potential prognostic cGVHD biomarkers, changed significantly at day 28 relative to baseline following treatment with itacitinib (Table 1). Levels of elafin, a marker of acute GVHD of the skin, were significantly reduced and levels of dickkopf-3 (DKK3), a marker of sclerotic and nonsclerotic cGVHD, were significantly increased in itacitinib cohorts only. Based on a repeated measures correlation analysis, both markers significantly correlated with overall clinical skin scores (elafin: r=+0.43; DKK3: r=-0.53; both P<0.001). Serum levels of other reported markers of cGVHD, including osteopontin, C-X-C motif chemokine ligand (CXCL) 9 and CXCL10, were significantly decreased exclusively in itacitinib-treated cohorts, and not in the CS only cohort. Some proteins, including matrix metalloproteinase (MMP) 3, increased in all cohorts, suggesting that changes in these proteins cannot be attributed to itacitinib alone, but may reflect response to CS; other proteins, such as suppression of tumorigenicity (ST2), remained unchanged in response to treatment in all cohorts. CS treatment alone resulted in an increase in naive CD4 T cells (CD4 +CD8 ->CD45RA +CCR7 -) and a corresponding reduction of CD4 effector memory T cells (CD4 +CD8 ->CD45RA -CCR7 +) within 28 days (Figure 1, cohort D). Changes in naive CD4 T cells following CS monotherapy were significantly attenuated by itacitinib ( P<0.05 vs CS at day 28), particularly at the 400 mg qd dose (Figure 1, cohort B), which demonstrated the best ORR at 6 months (53% with 400 mg qd vs 36% with CS). Conclusions: Analysis of patient samples from GRAVITAS-309 revealed that serum elafin and DKK3 levels significantly correlated with skin GVHD scores, possibly reflecting the systemic origin of observed skin manifestations. Serum levels of osteopontin, CXCL9, and CXCL10 were specifically reduced by itacitinib in patients with cGVHD and may represent potential pharmacodynamic markers. Observed changes in different peripheral T-cell populations in patients' samples following itacitinib treatment were consistent with those reported in murine GVHD models, suggesting a potential role of naive CD4 + T cells in driving this disease. Planned future analyses will include identification of novel biomarkers that correlate with organ involvement.

Outcome of Multiple Myeloma Patients Undergoing Allogeneic Stem Cell Transplant with Post-Transplant Cyclophosphamide - a Single Center Experience

Objective: The survival of multiple myeloma (MM) patients has improved significantly in the past decade with the development of new effective treatments including immunomodulators, monoclonal antibodies, and chimeric antigen receptor T cell (CAR-T) therapy. However, to date, none of the available treatments is curative for MM. In high-risk and relapsed patients, allogeneic stem cell transplant (allo-SCT) achieved long term survival in carefully selected MM patients. Here, we report our experience in MM patients who received allo-SCT at Thomas Jefferson University Hospital (TJUH). We aim to define the role of allo-SCT in the new era of MM treatment. Method: We retrospectively analyzed data of 57 MM patients who received allo-SCT at TJUH from 1996-2023. We used EZR software to analyze post-transplant outcomes including overall survival (OS) and disease-free survival (DFS) with Kaplan Meier method. Cumulative incidence (CI) calculated by EZR was used to determine relapse rate (RR) and non-relapse mortality (NRM). Median time to neutrophil and platelet engraftment was analyzed by Excel 2022. Results: The median age was 53 years old (range from 34-68 years old); 29 females and 28 males. Mean follow up time was 57.9 months (range from 0 to 253.6 months). Thirty-two patients received reduced intensity conditioning, 11 patients received myeloablative conditioning regimen, and 5 patients received non-myeloablative conditioning regimens. Thirty-one patients received matched related donor (MRD), 3 patients received matched unrelated donor (MUD), 21 patients received haploidentical (HI), and 2 patients received mismatched unrelated donor stem cell grafts. Time to neutrophil and platelet engraftment data was available for 33 and 29 patients, respectively. The median time to neutrophil engraftment was 12 days (range from 3-23 days). and the median time to platelet engraftment was 16 days (range from 6-51days). The 3-year and 5-year probabilities of OS were 53.2% (95% confidence interval is 38.7% to 65.7%) and 48.3% (95% confidence interval is 33.9% to 61.3%) respectively. The 3-year and 5-year probability of DFS were 37% (95% confidence interval is 21.6% to 52.5%) and 26.2% (95% confidence interval is 12.6% to 42%) respectively. Since 2009, most of the patients (33/36) in this study received post-transplant cyclophosphamide. Thus, we compared the OS for patients who received allo-SCT before 2009 and after 2009. The 5-years OS was 28.6% (95% confidence interval is 7.8% to 42.5%) and 62.7% (95% confidence interval is 43% to 77.2%) for patients who received allo-SCT before 2009 and after 2009 respectively (P=0.029). Among 43 patients with available relapse date data, the CI of relapse at 3 years was 36.9% (95% confidence interval 21.5%-52.4%) and the CI of NRM at 3 years was 26.1% (95% confidence interval 14%-39.9%). Thirty-five patients were evaluable for acute graft versus host disease (GVHD). Nine patients developed grade I-IV acute GVHD (25.7%) and 2 patients experienced grade III-IV acute GVHD (5.7%). Four out of 35 evaluable patients experienced chronic GVHD (11.4%): 2 patients had mild to moderate scleroderma, one patient had severe chronic skin GVHD and one had severe lung chronic GVHD. For 36 patients received allo-SCT after 2009, 3 died from relapse, 3 patients died from infection, 2 died from GVHD, 2 from unknown cause, one from brain bleeding, one from non-infectious pulmonary failure and one from acute heart failure. Conclusion: In MM patients with high-risk feature or relapsed/refractory disease, allo-SCT can be curative for approximately a third of the patients. Post-transplant cyclophosphamide coupled with contemporaneous MM treatments significantly increased the survival of allo-SCT MM patients in the modern era.

Abatacept-Prophylaxis Based Haploidentical Transplantation May Allow Sustained Engraftment and Offset Gvhd in Non-Malignant Disorders

Introduction: Non-malignant disorders (NMD) derive no benefit from graft-versus-host disease (GVHD) after allogeneic hematopoietic transplantation (HCT). Transplantation designed to optimize engraftment and immune reconstitution while minimizing GVHD and organ toxicities is desirable. Post-transplant cyclophosphamide (PTCy) decreases severe chronic GVHD risk in radiation-containing regimens for NMD when combined with serotherapy (anti-thymocyte globulin) (PMID: 22955919; PMID: 30500440). Abatacept effectively offsets GVHD following unrelated donor (URD) HCT (PMID: 33449816; PMID: 32813873). Based on these reports, NCT03128996 was developed for haploidentical transplantation in NMD after radiation-free reduced intensity conditioning (RIC) combining PTCy + Abatacept for GVHD prophylaxis. Serotherapy does not contribute to GVHD prophylaxis in this RIC approach. Outcomes focused on safety and GVHD- free donor engraftment in children with NMD and no better donor options. Method: Conditioning included alemtuzumab (day -22 to -19), fludarabine (day -8 to -4), melphalan (day -3) and thiotepa (day -4) as previously published (hydroxyurea prior to RIC was used in proliferative marrow disorders) (PMID: 32813873). Stem cell source was bone marrow (BM) or CD34-selected peripheral blood cells with a fixed CD3 cell dose of 1x10^6/kg recipient weight. GVHD prophylaxis included tacrolimus (day -1, with wean beginning 6-9 months post-HCT), PTCy on days +3 and +4, mycophenolate mofetil until day +28, and monthly abatacept doses until 13 months post-HCT. Survival, safety, donor chimerism, GVHD incidence, and incidence of post HCT infection were primary outcome measures. Results: Eleven patients 6 to 24 years old (median 9 years) underwent HCT for adrenoleukodystrophy ( 2), sickle cell disease (SCD) ( 6), aplastic anemia ( 1), second transplant for severe combined immunodeficiency ( 1) and STAT 5B gain-of-function mutation ( 1). Eight were trial participants and 3 treated according to trial guidelines. All patients tolerated abatacept infusions and engrafted with neutrophil recovery (>500/cu mm) at a median of 17 days (range 15-24 days). As of 7/31/2023, median follow up is 411 days (range 83-1979 days). The mean myeloid and T-cell chimerisms at D100 (n=10) and 1 year (n=6) were 97.8%+/- 5.3 and 96.3% +/- 6.4 and 98.6% +/- 3.3 and 95% +/-8.7, respectively. One patient with SCD has low myeloid engraftment (24%) at 7 months post-HCT (lymphoid 91%); a stem cell boost is planned after immune suppression with fludarabine/Cytoxan/ATG (PMID: 35798858). Viral reactivation was noted in 4 patients, none developed CMV disease or EBV post-transplant lymphoproliferation. One patient developed grade 1 acute GVHD. Of 6 evaluable patients, one developed localized chronic skin GVHD. This patient remains on systemic immune suppression beyond 13 months (ruxolitinib). The overall and GVHD-free survival at 1-year post HCT in evaluable patients (N=6) is 100 % and 83%, respectively. Conclusion: Promising preliminary results in this cohort support continuation of the trial with longer term follow-up. The effective suppression of GVHD without serious infectious complications in the first year post-HCT is encouraging. Virus reactivation was however noted early post-HCT and requires monitoring and prophylaxis. Incorporating abatacept into GVHD prophylaxis was successful in achieving desired outcomes; the phase 1 portion of the study is completed and the phase 2 trial and follow-up are ongoing.

Allogeneic Bone Marrow Transplantation from HLA-Identical or Haploidentical Donors for Children and Adolescents with Sickle Cell Disease: A Feasible Curative Option

The only curative option widely available for sickle cell disease (SCD) is bone marrow transplantation (BMT). Since few patients have a healthy matched sibling donor (MSD), haploidentical (haplo) donors have expanded the donor pool to approximately 90% of the patients. The addition of thiotepa to the Johns Hopkins conditioning therapy backbone dor haplo BMT showed durable engraftment and excellent overall survival. However, graft rejection has remained an important obstacle. Our challenge in these patients has been to augment the conditioning therapy to provide adequate engraftment, while maintaining a low transplant-related mortality. Methods: Retrospective data of all 26 patients with SCD followed by our group after MSD (n=7) and haplo (n=19) BMT performed in four different institutions. With a MSD, conditioning was rATG 4.5mg/kg, Busulfan (Bu, AUC 4,500), Fludarabine (Flu, 120mg/m²) or rATG, Bu, Cyclophosphamide (Cy, 200mg/kg) and with haplo donors, rATG 4.5mg/kg, Thiotepa 10mg/kg, Flu 150mg/m², Cy 29 mg/kg and TBI 2Gy. Patients were prepared to BMT with intense hypertransfusion/bleeding or erythrocytapheresis to keep HbS<30 and Hb~10g/dL, reticulocytes <10% for 2-3 months prior to BMT, with intensive chelation to keep ferritin <1,000ng/mL. The presence of donor specific antibodies would exclude the patient from undergoing BMT. Due to two consecutive secondary graft failures (no detectable donor cells despite initial engraftment) and two falling mixed chimerism among the first 13 patients undergoing haplo, the doses of the conditioning therapy were increased to Cy 50 mg/kg and TBI 4Gy in a single fraction, as previously used in our patients with aplastic anemia undergoing BMT. Six consecutive patients received this augmented conditioning therapy. All patients had serial chimerism measured by STR. The graft-versus-host disease (GVHD) prophylaxis included Cyclosporine - Methotrexate in MSD and post-transplant Cy/mesna, mycophenolate mofetil and sirolimus in haplo. Results: Between September 2016 and April 2023, 26 patients underwent BMT, with a median age of 11 years (4-20), half of them females, 7 with a MSD and 19 an haplo (4 siblings, 6 fathers, and 9 mothers); 77% of the donors had sickle cell trait. The graft was bone marrow in all but one patient with Sb thal and Hodgkin's lymphoma. The median follow-up was 15.5 months. All patients engrafted. BMT with MSD had excellent outcomes and stable chimerism. Among the first 13 patients undergoing haplo, secondary graft failure occurred very suddenly in two patients (CD34 cell doses of 2 and 8x10 6 CD34/kg), both male teenagers; two additional patients had a significant drop in chimerism up to 30% donor cells but responded to serial donor leukocyte infusions 1-5 x10 6 CD3/kg (2 and 6) and developed very mild skin GVHD. The other patients maintained > 89-100% donor cells. Thereafter, with the augmented conditioning regimen, all six consecutive patients have stable 100% donor chimerism. Acute II-III GVHD was observed in 34% and chronic GVHD in 15% of the patients. Viral reactivations (CMV, HHV6, BKV, HHV7 and EBV) were observed in all patients. Overall survival is 100% and rejection-free survival is 83% at 1 year (Figures 1, 2). Conclusions: Allogeneic BMT with an HLA-identical or haploidentical family donor was feasible to treat SCD with an excellent overall survival. With a larger cohort and longer follow-up, the long-term effects of this strategy will be thoroughly studied.

Memory T Cell Donor Lymphocyte Infusion As a Treatment for Viral Reactivations after Pediatric Haploidentical Hematopoietic Stem Cell Transplant

Introduction Viral reactivations, including cytomegalovirus (CMV), Epstein-Barr virus (EBV), adenovirus (ADV), human herpesvirus 6 (HHV6), and BK virus (BKV), constitute significant infectious complications following pediatric hematopoietic stem cell transplant (HSCT). abT cell depletion of haploidentical graft prevents risk of graft-versus-host disease (GVHD) but leads to delayed immune recovery and increased risk of viral reactivations. Donor lymphocyte infusion (DLI) with CD45RA-depleted memory T cells has been reported as an effective method to rapidly recover T cell immunity post HSCT. We hereby report the experience of CD45RA-depleted memory T cell infusion to treat viral reactivation following pediatric abT cell depleted haploidentical HSCT in our center over the last three years. Methods We retrospectively reviewed pediatric patients with abT cell depleted haploidentical transplant from related donors in our center from 2021-2023, and those who received memory T cell DLI for one or more viral reactivations. We routinely infuse CD45RA depleted memory T cells (dose at 1x10 6 CD3 T cells/kg) on the day of stem cell infusion prophylactically. Surplus of memory T cells harvested was cryopreserved for future use. Viral reactivations were monitored regularly after transplant by blood PCR assays (twice weekly for CMV; once weekly for EBV, ADV, and HHV-6). BK virus of urine and blood were monitored if patients became symptomatic for hemorrhagic cystitis. Once virus reactivation is identified, we start antiviral medications and infuse cryopreserved donor memory T cells for treatment. If subsequent virus PCR tests remain positive, donor memory T cells are infused every 1-2 weeks until the test is negative. Results A total of 52 memory T cell infusions were administered to 22 patients for viral reactivation after HSCT. Half of the patients (n=11) required only one infusion for viral clearance, whereas the other half received memory T cell infusion for 2-9 times. 19 patients (86.4%) are alive at time of data collection and analysis (July 2023), and 18 patients (81.8%) are in complete remission. The characteristics of patients and transplants are summarized in Table 1. The viral reactivations, which are intended to treat, include CMV (57.7%), EBV (7.7%), ADV (23.1%), BKV (15.4%) and HHV6 (9.6%), and some patients suffered from multiple viral reactivations at the time of memory T cell infusion (so the total percentage is more than 100%). The median day of memory T cell infusion post-transplant was day 46 (range 4-183). The median and most commonly used cell dose was 2 (0.025 - 20.5) x 10 6/kg CD3+ memory T cells (CD45RA depleted). The median duration to achieve negative PCR test for each virus are 13 days (CMV), 24 days (EBV),72 days (ADV), 15 days (HHV-6) and 88 days (BKV) (Figure 1). Thus most of the patients were CMV PCR negative within 15 days after DLI. All DLI were well tolerated. One patient (4.5%) was reported to suffer from stage 2 skin GVHD post donor memory T cell infusion. Conclusions CD45RA-depleted donor memory T cell infusion is a safe, feasible and effective treatment for viral reactivation following pediatric haploidentical stem cell transplant.

Diverse macrophage populations contribute to distinct manifestations of human cutaneous graft-versus-host disease.

Graft-versus-host disease (GvHD) is a major life-threatening complication of allogeneic haematopoietic stem cell transplantation (HSCT), limiting the broad application of HSCT for haematological malignancies. Cutaneous GvHD is described as a post-transplant inflammatory reaction by skin-infiltrating donor T cells and remaining recipient tissue-resident memory T cells. Despite the major influence of lymphocytes on GvHD pathogenesis, the complex role of mononuclear phagocytes (MNPs) in tissues affected by GvHD is increasingly appreciated. To characterize the identity, origin and functions of MNPs in patients with acute cutaneous GvHD. Using single-cell RNA sequencing and multiplex tissue immunofluorescence, we identified an increased abundance of MNPs in skin and blood from 36 patients with acute cutaneous GvHD. In cases of sex-mismatched transplantation, we used expression of X-linked genes to detect rapid tissue adaptation of newly recruited donor MNPs resulting in similar transcriptional states of host- and donor-derived macrophages within GvHD skin lesions. We showed that cutaneous GvHD lesions harbour expanded CD163+ tissue-resident macrophage populations with anti-inflammatory and tissue-remodelling properties including interleukin-10 cytokine production. Cell-cell interaction analyses revealed putative signalling to strengthen regulatory T-cell responses. Notably, macrophage polarization in chronic cutaneous GvHD types was proinflammatory and drastically differed from acute GvHD, supporting the notion of distinct cellular players in different clinical GvHD subtypes. Overall, our data reveal a surprisingly dynamic role of MNPs after HSCT. Specific and time-resolved targeting to repolarize this cell subset may present a promising therapeutic strategy in combatting GvHD skin inflammation.

Understanding and treatment of cutaneous graft-versus-host-disease.

The skin is the outermost mechanical barrier where dynamic immune reactions take place and is the most commonly affected site in both acute and chronic graft-versus-host disease (GVHD). If not properly treated, pain and pruritis resulting from cutaneous GVHD can increase the risk of secondary infection due to erosions, ulcerations, and damage of underlying tissues. Furthermore, resulting disfiguration can cause distress and significantly impact patients' quality of life. Thus, a deeper understanding of skin-specific findings of GVHD is needed. This review will highlight some promising results of recent pre-clinical studies on the pathophysiology of skin GVHD and summarize the diagnostic and staging/grading procedures according to the clinical manifestations of skin GVHD. In addition, we will summarize outcomes of various GVHD treatments, including skin-specific response rates.

First-line steroid-free systemic treatment of acute and chronic graft-versus-host disease after novel prophylaxis regimens.

In the early randomized trials the efficacy of calcineurin inhibitors (CNI) in the treatment of graft-versus-host disease (GVHD) was comparable to corticosteroids (CS), but these results became obsolete with the introduction of CNIs in prophylaxis. Recently several effective CNI-free GVHD prophylaxis regimens were introduced based on posttransplantation cyclophosphamide (PTCY) and αβ ex vivo T-cell depletion (αβ-TCD). Among patients treated under these protocols 34 patients with grade II-IV acute (aGVHD) and 40 with moderate and severe chronic (cGVHD) disease were treated with CNIs or other CS-free regimens as the first line. Overall response rate (ORR) was significantly higher in cGVHD than in aGVHD: 80% (95% CI 68-92) vs 47% (95% CI 30-64%), p = 0.0031. In aGVHD it was almost completely restricted to isolated stage III skin GVHD. In cGVHD patients with moderate disease ORR was higher than in severe: 96% (95% CI 88-100%) vs 56% (95%CI 32-81%), p = 0.0022. Two-year overall survival was 76% (95% CI 58-87%) in aGVHD and 95% (95% CI 81-99%) in cGVHD. Failure-free survival was 21% (95% CI 9-37%) in aGVHD and 81% (95% CI 64-91%) in cGVHD. Patients responding to steroid-free regimens had lower use of systemic antibiotics (p = 0.0095), antifungals (p = 0.0319) and antivirals (p < 0.0001).

Low Dose Ruxolitinib in Indian Haplo-Identical Transplant Patients with Steroid Refractory Acute Graft Versus Host Disease

Background: The number of allogeneic bone marrow transplants done in India is increasing by year. Unlike west, this region had got its own unique complications in the post-transplant period especially multi drug resistant gram negative bacterial sepsis reflecting in a higher transplant related mortality. With increasing number of Haplo-identical transplants, the problem of steroid refractory Graft versus host disease (GVHD) is a major reason for post-transplant morbidity and mortality. As most available immunosuppressive agents worsen cytopenia and in turn sepsis, we need a relatively safer method of managing steroid refractory GVHD in our setting. In this observational study, we used a lower dose of 5mg per day Ruxolitinib for a period of minimum 60 days post-transplant to look into clinical benefit. This dose was chosen considering the recovering platelet count and financial considerations in our resource limited setting. Method: This observational study was conducted from July 2019 to January 2022. A total of 11 steroid refractory GVHD Haploidentical transplant patients were chosen for data analysis that completed the scheduled dosage regimen of Ruxolitinib. Nine out of 11 patients were Acute Myeloid leukemia and two were Acute Lymphoblastic leukemia. The standard conditioning regimen in all was Fludarabine / Busulfan & Cyclophosphamide based conditioning. Additional GVHD medications used were PTCy, Tacrolimus, MMF and steroids with oral budesonide. Tab Ruxolitinib was started around Day +5 post steroids in people who were fitting into steroid refractory acyte GVHD at a fixed dose of 5mg OD for a minimum period of ten weeks. Two cases had one week dose interruption due to cytopenia. Results : At start of Ruxolitinib seven patients had Grade III gut and liver GVHD and rest four had grade II GVHD. Skin was grade II in all patients. When evaluated at Day +58 of Ruxolitinib, all patients were alive and nine of them were on tapering doses of steroids. All continued Tacrolimus at therapeutic doses. No excess bleeding or cytopenia requiring transfusion support happened during this period. As mentioned earlier two cases Ruxolitinib was stopped in view of platelet counts going below 20,000. On evaluation at day +100 post transplant, two patients continued to have grade II Liver, gut and skin GVH and one patient expired on day +48 to sepsis. Rest of eight patients had a Grade I skin, liver and gut GVHD and were able to continue Ruxolitinib further. We started Ruxolitinib taper in cases where steroids were stopped. As case numbers were very low and it's a pilot observation study, we didn't do detailed statistical analysis which may be misleading and give false promises. Conclusion: In our setup, we were finding it a difficulty to use the prescribed 10mg BD Ruxolitinib dose in adults due to fear of worsening cytopenia /sepsis and financial toxicity. We tried to observe the benefit of a lower dose in steroid refractory GVHD post Haplo-identical bone marrow transplant. No pharmaco-genetic assays were done and it's a very small sample size. This observational study revealed a better efficacy and tolerability of this dosing regimen in Indian Haplo-identical patients with a considerable response without compromising blood counts. The results are looking more promising to conduct this study in a bigger scale to benefit our patients from resource limited settings. Reference Zhao Y, Shi J, Luo Y, Gao F, Tan Y, Lai X, Yu J, Wei G, Huang H. Calcineurin Inhibitors Replacement by Ruxolitinib as Graft-versus-Host Disease Prophylaxis for Patients after Allogeneic Stem Cell Transplantation. Biol Blood Marrow Transplant. 2020 May;26(5):e128-e133. doi: 10.1016/j.bbmt.2020.01.012. Epub 2020 Jan 23. PMID: 31982545.

Haploidentical Hematopoietic Stem Cell Transplant Plus Add-Back NK Cells in Pediatric High-Risk ALL

Introduction: Natural killer (NK) lymphocytes are cells of innate immunity that protect against tumor and infections. NK cells recognize self and non-self HLA class I ligands, are regulated by a balance between activator and inhibitory signals through surface receptors, and can interact with HLA class I molecules on target cells. Killer-cell Immunoglobulin-like Receptors (KIRs) are inhibitory molecules expressed on NK cells and belong to the immunoglobulin superfamily. KIRs function to "educate" NK cells in effective defense against unhealthy self/non-self cells and tolerance against healthy self cells. NKs are thought to play a key role in preventing early relapse of hematologic malignancies, virus infection and graft versus host disease (GvHD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT).In B-/T-cell alpha/beta depleted haplo-HSCT, donor-versus-recipient allo-reactive NK cells can exert an efficient graft versus leukemia (GvL) effect, mediated by inhibitory KIRs where the HLA ligand is missing on recipient cells. Donor NK cells after haplo-HSCT are "immature" and not effective as the mature NKs. These immature NK cells are CD56bright, are derived from CD34+ stem cells, and mature to a CD56dim phenotype. The mature CD56dim NK cells are characterized by acquisition of KIRs, CD16 and CD57 in mature stages, which have functional significance in targeting and medicating their cytolytic activity. Based on these considerations, we performed haplo-HSCT with donor NK cell add-back to provide mature, functional immunological surveillance against tumor (MRD) and virus reactivation, which can frequently occur in manipulated haplo-HSCT for pediatric acute lymphoblastic leukemia (ALL). Methods: We evaluated the alloreactive effect of donor-derived NK cells in three pediatric high-risk ALL who underwent B-/T-cell alpha/beta depleted haplo-HSCT followed by donor NK infusion. Patients' characteristics are summarized in the Table. All 3 patients were male; median age was 13 months. Patients 1 and 2 had infant ALL, and patient 3 had refractory-relapsed (r/r) ALL. All patients received a median of 3 lines chemotherapy. Patient 1 received a prior allo-HSCT. Patients 1 and 2 received chemo-based conditioning regimens consisting of thyotepa, and fludarabine; In addition, patient1received treosulfan, and patient 2 received busulfan. Treosulfan was given to patient 1, due to less toxicity profile given prior allo-HSCT. Patient 3 received Total Body Irradiation (TBI), thyotepa, and fludarabine. All patients received rituximab and letermovirfor EBV and CMV prophylaxis, respectively, for all patients. Mother was Donor for all patients. Median CD34+, CD19+, CD3+-alpha/beta cell dose was 8.8, 0.05, 0.41 x 106/kg, respectively. NK cell allo-reactivity was tested by evaluating KIR genotyping and KIR/KIR-ligand mismatch in graft-versus-host direction. All three patients present KIR/KIR-ligand mismatch. Results: Engraftment was day +13, +14 and +19 for ANC, and +14, +18 and +17 for PLT (for both >20K and >50K), for patients 1, 2 and 3, respectively. NK cell number were monitored on day +7, +14, +21 and +28 (data pending). Patients received NK cell infusion on day 30 +/- 2 days. No infusion reactions were observed. MedianNK infused were 256x106/kg. None of the patients developed CMV, EBV or ADV reactivation. Patient 2 developed Grade 2 acute GvHD (skin) treated with steroids. No Grade GvHD 3-4 was observed. Median follow up was 58 days. All patients had full donor chimerism at day 30 ±2. All patients are currently in hematological CR; patient 1 converted to positive MRD at nine months from transplant. Conclusion: Alloreactive NK cell add-back infusion after B-/T-cell alpha/beta depleted haplo-HSCT could represent an effective option to improve transplant outcome and prevent virus reactivation. These NK cells may improve efficacy by enhancing GvL and could contribute to maintain the "disease control" through immunologic surveillance in high-risk ALL. Indeed, NK killing, which is higher in mature NK cells, depends on acquisition of sequential phenotypic maturation. Thus, infusion of mature donor NK cells may help to maintain control of MRD and virus reactivation through immunologic surveillance. Although our preliminary observations seem to be promising, this hypothesis should be confirmed in clinical trial of a larger number of patients. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Associations of Minor Histocompatibility Antigens with Clinical Outcomes Following Allogeneic Hematopoietic Cell Transplantation

Introduction Donor T-cell recognition of tumor-presented minor histocompatibility antigens (mHAs) is thought to be a central mediator of the therapeutic graft versus leukemia (GvL) effect following allogeneic hematopoietic cell transplantation (alloHCT). In contrast, graft versus host disease (GvHD) develops when donor T-cells react to mHAs presented by normal recipient cells. While the role of mHAs in outcomes following alloHCT is recognized, it has not been well-characterized. It remains unclear whether GvL and GvHD are mediated by the cumulative effect of total mHAs in a donor-recipient pair (DRP) or individual immunodominant mHAs. We hypothesized that an increased mHA count and individual mHAs would be associated with lower relapse and disease-related mortality (DRM) and/or increased GvHD mortality. To this end, we predicted genome-wide mHA peptides in a large patient population and analyzed the associations between clinical outcomes and 1) the total number of predicted class I and class II mHAs, and (2) individual and groups of mHAs. Methods The study population consisted of 2249 European American DRPs in the DISCOVeRY-BMT dataset treated for Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS) with alloHCT. To predict mHAs in a DRP, we translated nonsynonymous SNP alleles present in alloHCT recipients, but absent in their donor, into all possible peptides of varying lengths that would encompass the altered amino acid. To identify mHAs most likely to be immunogenic, peptides were filtered based on (1) source protein gene expression data in GvL and GvHD target tissues, including AML, liver, skin, and colon, from UCSC's Xena Dataset repository and (2) recipient HLA binding affinity from netMHCpan. To test the association of mHA count and individual mHAs with all-cause mortality (OS) and leukemia-free survival (LFS) we used cox proportional hazard models and competing risk models for DRM, treatment-related mortality (TRM), and GvHD mortality. Individual mHA analyses were stratified by HLA type to recognize that T-cell responses depend on HLA-mHA complexes. Models were adjusted for clinical covariates. Bonferroni correction for multiple testing was based on the number of independent SNPs. Results Patients with a class I mHA count greater than the population median had a 39% (HR=1.39, 95%CI 1.005,1.772, P=0.046) increase in hazard of GvHD mortality compared to those with a count less than the median. Patients with a class II mHA count greater than the population median had a decreased overall survival compared to those with a count less than the median (Fig. 1, P=0.029). In recipients with HLA-B*08:01, the class I mHA DLRCKYISL was associated with increased risk of GVHD mortality (HR=2.84, 95%CI 1.52,5.31, P=0.01). Within HLA-B*40:01, WEHGPTSLL was associated with decreased LFS (HR=1.94, 95%CI 1.27,2.95, P=0.044). Within HLA-C*03:04, STSPTTNVL was associated with increased risk of DRM (HR=2.32, 95%CI 1.5,3.6, P=0.008). In recipients with HLA-DRB1*15:01, the class II mHA YQEIAAIPSAGRERQ was associated with increased risk of TRM (HR=3.05, 95%CI 1.75,5.31, P=0.02). Two mHAs, WEHGPTSLL and STSPTTNVL, were found within the HLA haplotype B*40:01-C*03:04. Recipients with both mHAs (versus neither) had a greater hazard of 1-year all-cause mortality (HR=3.58, P=7.9×10-5) and DRM (HR=3.65, P=0.003) (Fig. 2). Patients with either mHA (versus neither) had greater 1-year all-cause mortality (HR=1.69, P=0.008) and increased DRM (HR=2.05, P=0.008) Conclusions The number of class I mHAs in a DRP was associated with increased GvHD mortality, which is consistent with our hypothesis. We also found two mHAs correlated with GvHD mortality and DRM which may represent increased GvH effects driven by these peptides. However, contrary to our hypothesis, an increased number of class II mHAs was correlated with greater risk of all-cause mortality that may be due to decreased LFS. Similarly, we found two mHAs correlated with increased DRM and decreased LFS. These two mHAs are found in an HLA haplotype where they exhibit a dose effect relationship with the risk of DRM and decreased OS. These findings may reflect an unexpectedly attenuated GvL effect that requires further investigation. Our study reports the first large scale investigation of the role of predicted mHA peptides in clinical outcomes following alloHCT. If validated, these results may be used to help guide clinical decision making. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Real World Favourable Experience of Haematopoietic Stem Cell Transplantation during Acute Coronavirus Disease 2019 in a Highly-Vaccinated Asian Population

Background Patients with high-risk haematological malignancies often progress and succumb to their disease without a timely haematopoietic stem cell transplantation (HCT). However, in patients undergoing HCT following acute Coronavirus disease 2019 (COVID-19) infection, there is a significant morbidity and mortality risk. Few recent reports suggest that allogeneic and autologous HCT may be feasible in patients who have recovered from COVID-19, but there is little data on the optimal timing and safety of HCT following the infection. High rates of COVID-19 community transmission were observed in a highly-vaccinated population of Singapore between September 2021 and April 2022, affecting many HCT recipients. In this study at the largest tertiary transplant centre in Singapore, we analyzed the outcome of patients who underwent HCT following COVID-19 infection in the preceding 120 days or with active COVID-19 infection during transplant. Methods We conducted a retrospective analysis of consecutive patients admitted to Singapore General Hospital for planned HCT from September 2021 and April 2022. Written informed consent was obtained, and patients were followed up for transplant-related outcomes. The date of diagnosis of COVID-19 was based on the first positive SARS-CoV-2 PCR nasopharyngeal swab. Patients who were diagnosed with COVID-19 within 120 days prior to stem cell infusion were included in the study. Results We studied 10 allogeneic and 1 autologous HCT patients, with acute myeloid leukaemia (n=3), acute lymphoblastic leukaemia (n=2), chronic myeloid leukaemia (n=2), myelofibrosis (n=1), severe aplastic anaemia (n=1), Hodgkin lymphoma (n=1) and multiple myeloma (n=1). Median interval between diagnosis of COVID-19 to HCT infusion was 53 days (range 1-118). 6 were tested negative by PCR and 2 were prolonged low-level viral shedders detectable by PCR, prior to HCT. 3 patients were diagnosed with COVID-19 immediately prior to HCT infusion, at Days -1, -3 and -5 respectively. Median duration of COVID-19 infection defined by time to negative PCR was 20 days. All allogeneic HCT patients had 2 doses of COVID-19 mRNA vaccines (Pfizer-BioNTech BNT162b2 or Moderna mRNA-1273) prior to infection, and the autologous HCT patient was unvaccinated. Median receptor binding domain IgG serology titre (Abbott assay) in vaccinated patients was 1301 AU/ml at the time of COVID-19 diagnosis. COVID-19 disease severity by WHO guidelines was mild in 9, moderate in 1 and critical in 1 patient. 8 patients received antivirals; 5 of them had concurrent monoclonal antibodies (sotrovimab, n=4; casirivimab-imdevimab, n=1). Median age at HCT was 53 years (range 26-70); 64% of patients had low-risk HCT-comorbidity index, 45% were male, and 55% were of high-risk by the disease risk index. Allogeneic HCT patients received peripheral blood stem cells from matched siblings donors (MSD, n=3), matched unrelated donors (MUD, n=2) or haploidentical donors (n=5). 50% of patients received myeloablative conditioning regimen (n=5); and prophylaxis for graft-versus-host disease (GvHD) included calcineurin inhibitors and/or mycophenolate mofetil. Haploidentical transplant patients received post-transplant cyclophosphamide (PTCy, n=3) or ex-vivo TCRalpha-beta depleted grafts (n=2). A relapsed AML patient received haploidentical TCRalpha-beta depleted graft without conditioning regimen. A median of 5.5 x 10^6 CD34+ cells/kg (range 2.9-10.1) was infused. Median time to neutrophil and platelet engraftment were 10 days (range 10-17) and 12 days (range 10-20) respectively, in both MSD and MUD recipients (Table 1), comparable to that of non-COVID-19 cohorts. 2 patients died of non-relapse pulmonary complications on D+43 and D+50 post HCT respectively. 2 out of 10 allogeneic HCT patients developed grade II acute GvHD of skin, but none grade III-IV acute GvHD. Median follow up was 103 days (range 43-208), and GvHD-free/relapse-free survival (GRFS) among surviving patients at D+100 was 78%. There was no evidence of COVID-19 reinfection or late complications, or increase in viral reactivation of CMV, EBV and HHV6. Discussion Our study suggests that timely HCT can be safely performed with favourable outcome for patients with haematological malignancies, following acute COVID-19 infection in a fully-vaccinated cohort. Immunization, viral therapeutics and a careful disease risk-benefit assessment play a crucial role. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

ATYPICAL PRESENTATION OF FAT EMBOLISM SYNDROME IN AN IMMUNOCOMPROMISED PATIENT

ATYPICAL PRESENTATION OF FAT EMBOLISM SYNDROME IN AN IMMUNOCOMPROMISED PATIENT

Longitudinal proteomics study of serum changes after allogeneic HSCT reveals potential markers of metabolic complications related to aGvHD

Even though hematopoietic stem cell transplantation (HSCT) allows successful treatment for many malignant and non-malignant disorders, its curative potential remains limited by severe side effects, including infections and other transplant-related complications such as graft-versus-host disease (GvHD). This study examined changes in serum proteome via high-performance two-dimensional gel electrophoresis (2-DE) during HSCT to search for diagnostic biomarkers for post-HSCT complications. Longitudinal proteomic analysis revealed proteins related to metabolic complications and hemolytic anemia. Retinol-binding protein 4 (RBP4), a reliable marker of insulin resistance, was identified, and is possibly associated with the onset mechanism of acute graft-versus-host disease (aGvHD) and/or skin GvHD. Although the cause of insulin resistance is not fully understood, it is thought to be associated with adipocytes inflammation induced by RBP4, iron overload and hemolytic anemia after HSCT, as observed in this study. The present study has demonstrated that insulin resistance and metabolic complications could be immediate complications after transplantation and are associated with aGvHD. The biomarkers revealed in this study are promising tools to be used for improving the early diagnosis of HSCT-associated complications, especially aGvHD, possibly even before clinical manifestations.

Established and Emerging Treatments of Skin GvHD

Graft-versus-host disease (GvHD) of the skin is a severe allo-immune reaction and complication following allogeneic stem cell transplantation. Over the past years, intensive pre-clinical research has led to an improved understanding of the pathophysiology of acute and to a lesser extend chronic GvHD. This has translated into the approval of several new agents for the treatment of both forms of GvHD. This review summarizes the most recent advances in underlying pathomechanisms, clinical trials and newly approved agents for GvHD, with a special focus on skin involvement.