Diagnosis of Post-Hematopoietic Stem Cell Transplantation Bronchiolitis Obliterans Syndrome in Children: Time for a Rethink?

Hematopoietic stem cell transplantation (HSCT) is undertaken in children with the aim of curing a range of malignant and nonmalignant conditions. Unfortunately, pulmonary complications, especially bronchiolitis obliterans syndrome (BOS), are significant sources of morbidity and mortality post-HSCT. Currently, criteria developed by a National Institutes of Health (NIH) working group are used to diagnose BOS in children post-HSCT. Unfortunately, during the development of a recent American Thoracic Society (ATS) Clinical Practice Guideline on this topic, it became apparent that the NIH criteria have significant limitations in the pediatric population, leading to late diagnosis of BOS. Specific limitations include use of an outdated pulmonary function testing reference equation, a reliance on spirometry, use of a fixed forced expiratory volume in 1 second (FEV1) threshold, focus on obstructive defects defined by FEV1/vital capacity, and failure to acknowledge that BOS and infection can coexist. In this review, we summarize the evidence regarding the limitations of the current criteria. We also suggest potential evidence-based ideas for improving these criteria. Finally, we highlight a new proposed criteria for post-HSCT BOS in children that were developed by the authors of the recently published ATS clinical practice guideline, along with a pathway forward for improving timely diagnosis of BOS in children post-HSCT.

Ruxolitinib en pacientes que recibieron trasplante alogénico de células progenitoras hematopoyéticas y desarrollan enfermedad de injerto contra huésped (EICH) crónica, refractarios o dependientes a los corticoides y que han recibido terapia inmunosupresora a dosis máxima / Ruxolitinib in patients who received allogeneic hematopoietic progenitor cell transplantation and develop chronic graft-versus-host disease (GVHD), refractory or dependent to corticosteroids and who have received maximum-dose immunosuppressive therapy

INTRODUCCIÓN: Cuadro clínico: La Enfermedad de Injerto Contra Huésped (EICH) es una complicación multisistémica frecuente y potencialmente mortal del Trasplante Alogénico de Células Progenitoras Hematopoyéticas (TACPH). Las complicaciones están influenciadas por factores relacionados con el paciente como la edad, el estado funcional, comorbilidades, y pueden afectar la piel, boca, ojos, pulmón, hígado e intestinos. La EICH crónica se presenta entre el 30% a 70% de pacientes post TACPH. En estos pacientes, la mortalidad por EICH crónica puede alcanzar hasta un 10%, siendo una de las principales causas de muerte, superada únicamente por la recaída de la enfermedad primaria. La mortalidad por EICH crónica puede atribuirse tanto a complicaciones propias de la enfermedad como a la terapia inmunosupresora, y está fuertemente correlacionada con la respuesta al tratamiento de primera línea. Por otro lado, la EICH crónica contribuye de manera sustancial a la morbilidad, deterioro funcional y disminución de la calidad de vida. Los pacientes que viven con EICH crónica tienen el doble de probabilidad de desarrollar otra enfermedad grave o potencialmente mortal, con un mayor riesgo de segundas neoplasias, enfermedad cardiovascular, infecciones y complicaciones pulmonares. Estos pacientes suelen experimentar ansiedad, angustia, menor resiliencia, deterioro de la calidad de vida, estado funcional deficiente y pobre funcionalidad social. Entre los factores de riesgo se ha descrito el aumento de la edad del huésped, el estado del citomegalovirus (CMV) del donante y del huésped, la seropositividad del virus de Epstein-Barr (VEB) del donante, el trasplante de células madre de sangre periférica versus trasplante de médula ósea, EICH aguda previa, la presencia de un ambiente estéri

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

BACKGROUND: In 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. METHODS: In 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. RESULTS: In 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. CONCLUSIONS: Among 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.).

Haematopoietic Stem Cell Transplantation (HSCT) for Primary Immune System Disorders in Children: A Single Centre Experience.

OBJECTIVE: To determine the outcomes of allogeneic HSCT in children with primary immune system disorders (PID). STUDY DESIGN: Descriptive Cross-sectional study. Place and Duration of the Study: Armed Forces bone marrow transplant centre / National Institute of Bone Marrow Transplant (AFBMTC / NIBMT), Rawalpindi, Pakistan, from October 2012 to December 2021. METHODOLOGY: Data of all cases undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic HSCT. All patients presenting to AFBMTC / NIBMT with PID, age <12 years. Patients with organ dysfunction secondary to repeated infections were excluded from the study. Data of all patients and their donors undergoing HSCT for immune system disorders were analysed for variables affecting outcome and overall survival in the first 180 days after allogeneic bone marrow transplant. Neutrophil engraftment was defined as absolute neutrophil count ≥0.5 × 109/L for 3 consecutive days, while platelet engraftment as platelet count ≥20 × 109/L without platelet transfusion for one week. Overall survival (OS) was taken as time from the date of HSCT till day + 180 post-transplant. RESULTS: A total of 42children including 29 boys and 13 girls underwent HSCT for PID. The mean age was 2.1±2.8 years. Underlying diagnosis was haemophagocytic lymphohistiocytosis (HLH), severe immune deficiency (SCID), leukocyte adhesion defect (LAD), X-linked agammaglobulinemia, chronic granulomatous disease (CGD) and Job's syndrome in 18 (42.9%), 16 (38.1%), 3(7.1%), 2 (4.8%), 2 (4.8%) and 1 (2.4%) patients respectively. Thirty-one (73.8%) children had fully HLA-matched donors while 11 (26.2%) had haplo-matched donors. Major immediate post-transplant complications were febrile neutropenia, mucositis and SOS/VOD in 31 (73.8%), 9 (21.4%) and 4 (10.0%) cases, respectively. Eight (19.0%) had CMV reactivation, acute GVHD was seen in 17 (40.4%) cases, while 1 (2.3%) case had chronic GVHD. Twelve (28.6%) patients died, out of which 5 had graft failure, 3 had VOD, 2 had pneumonia, 1 had severe GVHD, and 1 died due to seizures. Overall survival (OS) in this study was 71.4% with survival reaching up to 80.6% in fully matched HSCT. CONCLUSION: HLH and SCID were the commonest immune disorders requiring HSCT. Graft failure leading to neutropenic sepsis was the commonest cause of mortality. OS was better in fully matched HSCT as compared to haplo-identical HSCT. KEY WORDS: Immune deficiency, Severe combined immunodeficiency, Haematopoietic stem cell transplantation.

A potential mechanism by which aspiration of duodenogastric fluid augments the risk for bronchiolitis obliterans syndrome after lung transplantation.

OBJECTIVE: Aspiration of duodenogastric refluxate may damage the respiratory epithelium of lung allografts in transplant recipients. We sought to define a mechanism by which aspiration of duodenogastric fluid augments the risk of bronchiolitis obliterans syndrome after lung transplant in a murine model. METHODS: We analyzed the immunological effects of acute aspiration of duodenogastric fluid (0.5 mL/kg) on transplant naive (strain DBA/2J) and transplanted mice (strain B6D2F1/J to strain DBA/2J). Serum antibodies to the lung self-antigens (SAgs) K-alpha1 tubulin and collagen-V were determined by enzyme-linked immunosorbent assay. Exosomes were isolated from serum, and immunoblot membranes were probed for antibodies to lung SAgs. Lung sections were assessed for fibrotic burden and obliterative bronchiolitis lesions by histologic and immunohistochemical analyses, including trichrome staining. RESULTS: Transplanted mice that received duodenogastric fluid developed higher levels of antibodies to the lung SAgs K-alpha1 tubulin and collagen-V and exosomes with lung SAgs on posttransplant days 14 and 28 than transplanted mice with sham aspiration or transplant naive mice (with and without aspiration). All lung allografts demonstrated severe grade A4 rejection on posttransplant day 14, with the highest mean fibrotic burden and mean number of obliterative bronchiolitis-like lesions per microscopic field on day 28 in recipients with aspiration. CONCLUSIONS: This study links aspiration of duodenogastric fluid after lung transplant to higher autoimmune responses to lung SAgs and the release of circulating exosomes with lung SAgs, which together promote sustained immune responses leading to extensive lung parenchymal damage and, ultimately, severe obliterative bronchiolitis-the histologic hallmark of bronchiolitis obliterans syndrome.