Alternative donor transplant of benign primary hematologic disorders

A Validated Risk Stratification That Incorporates MAGIC Biomarkers Predicts Long-Term Outcomes in Pediatric Patients with Acute GVHD

Acute graft versus host disease (GVHD) is a common and serious complication of allogeneic hematopoietic cell transplantation (HCT) in children but overall clinical grade at onset only modestly predicts response to treatment and survival outcomes. Two tools to assess risk at initiation of treatment were recently developed. The Minnesota risk system stratifies children for risk of nonrelapse mortality (NRM) according to the pattern of GVHD target organ severity. The Mount Sinai Acute GVHD International Consortium (MAGIC) algorithm of 2 serum biomarkers (ST2 and REG3α) predicts NRM in adult patients but has not been validated in a pediatric population. We aimed to develop and validate a system that stratifies children at the onset of GVHD for risk of 6-month NRM. We determined the MAGIC algorithm probabilities (MAPs) and Minnesota risk for a multicenter cohort of 315 pediatric patients who developed GVHD requiring treatment with systemic corticosteroids. MAPs created 3 risk groups with distinct outcomes at the start of treatment and were more accurate than Minnesota risk stratification for prediction of NRM (area under the receiver operating curve (AUC), .79 versus .62, P = .001). A novel model that combined Minnesota risk and biomarker scores created from a training cohort was more accurate than either biomarkers or clinical systems in a validation cohort (AUC .87) and stratified patients into 2 groups with highly different 6-month NRM (5% versus 38%, P < .001). In summary, we validated the MAP as a prognostic biomarker in pediatric patients with GVHD, and a novel risk stratification that combines Minnesota risk and biomarker risk performed best. Biomarker-based risk stratification can be used in clinical trials to develop more tailored approaches for children who require treatment for GVHD.

KIR in Allogeneic Hematopoietic Stem Cell Transplantation: Need for a Unified Paradigm for Donor Selection

Allogeneic hematopoietic stem cell transplantation (aHSCT) is a lifesaving therapy for hematological malignancies. For years, a fully matched HLA donor was a requisite for the procedure. However, new immunosuppressive strategies have enabled the recruitment of viable alternative donors, particularly haploidentical donors. Over 95% of patients have at least two potential haploidentical donors available to them. To identify the best haploidentical donor, the assessment of new immunogenetic criteria could help. To this end, the clinical benefit of KIR genotyping in aHSCT has been widely studied but remains contentious. This review aims to evaluate the importance of KIR-driven NK cell alloreactivity in the context of aHSCT and explain potential reasons for the discrepancies in the literature. Here, through a non-systematic review, we highlight how the studies in this field and their respective predictive models or scoring strategies could be conceptually opposed, explaining why the role of NK cells remains unclear in aHCST outcomes. We evaluate the limitations of each published prediction model and describe how every scoring strategy to date only partly delivers the requirements for optimally effective NK cells in aHSCT. Finally, we propose approaches toward finding the optimal use of KIR genotyping in aHSCT for a unified criterion for donor selection.

The impact of donor-specific anti-human leukocyte antigen antibodies in salvage haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide in patients with nonmalignant disorders

The presence of donor-specific anti-human leukocyte antigen (HLA) antibodies (DSAs) has been recognized as a major risk factor for graft failure (GF) after haploidentical hematopoietic cell transplantation with posttransplant cyclophosphamide (haplo-PTCy). However, the role of DSAs in salvage haplo-PTCy for rescuing patients with nonmalignant disorders (NMDs) has not yet been reported. The present study retrospectively analyzed 22 patients with NMDs who underwent salvage haplo-PTCy from January 2008 to December 2017. The median age at the time of the rescue haplo-PTCy was 9 years (range, 1-26 years). Median time from the first transplant to second haplo-PTCy was 56 days (range, 37-591 days). Among all patients, six (27.3%) had DSAs, with a median DSA strength (mean fluorescence intensity [MFI]) of 5201 (range, 1412-11,543) in the first DSA testing. In addition, the median DSA MFI was 2672 (range, 832-10,498) before the bone marrow infusion. Overall, GF occurred in 5 (25%) of the 20 assessable patients. Three of four (75%) patients with DSAs experienced GF versus 2 of 16 (12.5%) DSA-negative patients (P = 0.032). The median DSA MFI for patients with GF was 6437 (range, 1412-10,498) versus 1845 (range, 832-2672) for those who engrafted or had early death (P = 0.030). One-year event-free survival was significantly lower in DSA-positive patients than in those without DSAs (16.7% vs. 62.5%, P = 0.002). DSA-negative patients had an acceptable 1-year survival of 62.5%. In conclusion, this study suggests that DSAs may be associated with deleterious outcomes after salvage haplo-PTCy in patients with NMDs.

T-cell replete Haplo-identical HSCT with Post transplant Cyclophosphamide for Hemoglobinopathies: A retrospective analysis from a single center

We report herein haplo-identical hematopoietic stem cell transplantation (haplo-HSCT) by T-cell replete graft infusion, with post-transplant cyclophosphamide (PTCy) in patients with hemoglobinopathies. Patients received a conditioning regimen consisting of either busulfan, fludarabine, cyclophosphamide, with antithymocyte globulin or Thiotepa, antithymocyte globulin, fludarabine, cyclophosphamide, and TBI. The median follow-up period was 14.3 months (range, 1-63 months). Overall survival (OS) and disease-free survival (DFS) were 80% and 62.8%, respectively. Incidence of secondary graft failure was 14%. Incidences of acute graft-versus-host disease (aGvHD) and chronic graft-versus-host disease (cGvHD) were 22.5% and 20%, respectively. Cytomegalovirus (CMV) reactivation was observed in 42.5% of cases. The 100-day mortality rate was 20%, with sepsis and aGvHD being the predominant causes of death.

Infectious complications after hematopoietic stem cell transplantation for primary immunodeficiency in children: A multicenter nationwide study

PURPOSE

The aim of this nationwide study was to evaluate the characteristics of bacterial infections (BI), invasive fungal disease (IFD), and viral infections (VI) in pediatric patients with PID after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

PATIENTS AND METHODS

In total, 114 HSCT recipients were enrolled into the study. At least one infectious complication (IC) was diagnosed in 60 (52.6%) patients aged 0.1-17.7 years, that is, 59.5% with SCID and 49.4% with non-SCID.

RESULTS

Among 60 HSCT recipients diagnosed with at least one IC, 188 episodes of infectious complications (EIC) were recorded, that is, 46.8% of BI, 41.5% of VI, and 11.7% of proven/probable IFD. According to PID and HSCT donor type, the incidence of EIC was comparable (P = .679). The localization of infections differed significantly due to PID type (P = .002). After each HSCT donor type, the most common site of infection was GI. Overall, BI caused by Gram-positive strains (59.1%) were prevalent, especially Staphylococcaceae. The multidrug-resistant (MDR) pathogens were diagnosed in 52.3%, especially ESBL + Enterobacteriaceae. The profile of VI was comparable for SCID and non-SCID patients (P = .839). The incidence of IFD was comparable for each PID and HSCT donor type. Survival after infection was 91.5% and was comparable for PID and HSCT donor type.

CONCLUSIONS

The rate of patients diagnosed with IC among pediatric PID-HSCT recipients did not depend on PID type, but rather on HSCT donor type. The localization of IC depended on PID and HSCT donor type. Within bacterial infections, predominated Gram-positive strains and the MDR pathogens were responsible for more than half of EIC.

Posttransplant cyclophosphamide in allogeneic bone marrow transplantation for the treatment of nonmalignant hematological diseases

We present a single-center retrospective series of allogeneic bone marrow transplantation (BMT) with the use of posttransplant cyclophosphamide (PTCy) in the setting of nonmalignant hematological conditions. Nine patients were treated between 2013 and 2019. Nonmyeloablative conditioning consisted of antithymocyte globulin, fludarabine, low-dose cyclophosphamide, and total body irradiation (200cGy) followed by allogeneic bone marrow infusion. Post-BMT GVHD prophylaxis was with PTCy, tacrolimus, and mycophenolate mofetil. At a median follow-up of 24 months (range 4, 63), all patients are alive, with donor-derived hematopoiesis and free of significant acute or chronic GVHD. Donors were haploidentical (n = 6), fully matched unrelated (n = 2), and fully matched sibling (n = 1). Neutrophil and platelet engraftment occurred at a median of 21 days and 33 days, respectively, after transplantation. Three patients (3/9, 33%) experienced stage 1-2 acute skin GVHD. The only cases of chronic GVHD are in three patients (3/9, 33%) with ocular disease (two mild, one moderate). No patient has required systemic immunosuppression beyond 12 months after BMT. PTCy-based nonmyeloablative allogeneic BMT is safe and effective for nonmalignant hematologic conditions and should be prospectively compared with historical regimens.

Review of Haploidentical Hematopoietic Cell Transplantation

Use of haploidentical (haplo) donors for hematopoietic cell transplantation (HCT) has significantly increased in the last decade. The major advantage with this strategy is universal availability and faster acquisition of the donor, along with affordability and provision of immunotherapy in post-transplantation period. Historically, haplo-HCT was associated with compromised outcomes because of high rates of graft-versus-host disease and graft failure, but after the development of a post-transplantation high-dose cyclophosphamide strategy, which results in selective T-cell depletion, these issues have been addressed to a large extent. Nevertheless, graft failure, high treatment-related mortality due to graft-versus-host disease, infections, delayed immune reconstitution, and disease relapse remain significant concerns. As the experience with haplo-HCTs grows, the clinical outcomes are becoming more at par with those seen with fully matched unrelated donor allogeneic HCTs.

T Cell-Depleted and T Cell-Replete HLA-Haploidentical Stem Cell Transplantation for Non-malignant Disorders

PURPOSE OF REVIEW

Hematopoietic stem cell transplantation (HSCT) is a treatment option for children with malignant and non-malignant disorders as well as an expanding number of inherited disorders. However, only a limited portion of patients in the need of an allograft have an HLA-compatible, either related or unrelated, donor. Haploidentical HSCT is now considered a valid treatment option, especially in view of the recent insights in terms of graft manipulation. This review will offer an overview of clinical results obtained through the use of haploidentical HSCT in non-malignant diseases. We will analyze major advantages and drawbacks of both T cell depleted and unmanipulated HSCT, discussing future challenges for further improving patients' outcome.

RECENT FINDINGS

T cell depletion (TCD) aims to reduce the morbidity and mortality associated with graft-versus-host disease (GvHD). However, the delayed immune recovery and the risk of graft failure still remain potential problems. In the last years, the use of post-transplant cyclophosphamide has been shown to be an alternative effective strategy to prevent GvHD in recipients of haploidentical HSCT. Recent data suggest that both T cell depleted and T cell-replete haplo-HSCT are suitable options to treat children with several types of non-malignant disorders lacking an HLA-identical donor.

Clinical Features Before Hematopoietic Stem Cell Transplantation or Enzyme Replacement Therapy of Children With Combined Immunodeficiency

BACKGROUND

Survival of children with combined immunodeficiency is strongly related to patient's age and clinical situation at the time of hematopoietic stem cell transplantation (HSCT). We describe the clinical features before HSCT or enzyme replacement therapy (ERT) in a cohort of children treated in a National Reference Unit.

METHODS

A retrospective study of children with CIDs treated in our Hospital during a 20-year period (1995-2014) was performed, analyzing their clinical situation before HSCT/ERT.

RESULTS

Thirty-one children were included. Risk factors such as family history or consanguinity were present in 35% of cases, but only 3 children (9%) were initially studied because of family history. Median ages at clinical onset, diagnosis and HSCT/ERT were 3.3, 5.6 and 8.1 months, respectively. All patients had lymphopenia before HSCT/ERT. At the time of admission to our unit, 68% of cases had abnormal lung auscultation, 72% were malnourished, 45% reported chronic gastroenteritis and 35% had hepatosplenomegaly. Before HSCT/ERT, respiratory infections and sepsis episodes were documented in 80% and 42% of cases, respectively. In 23% of children, a viral systemic infection was confirmed. The mortality rate was 35%, and 72% of children who died had Gram-negative bacterial sepsis or a viral infection.

CONCLUSIONS

The present study shows the characteristics and outcome of children with CIDs in the absence of neonatal screening. Although all our patients had lymphopenia and most of them had suffered relevant infections or had a positive family history, these factors were not identified early. Respiratory and systemic viral infections were the main source of infection with important implications in clinical outcome. Our results highlight the importance of the implementation of neonatal screening, to improve survival rates.

Haploidentical hematopoietic stem cell transplantation with post-transplant high-dose cyclophosphamide in high-risk children: A single-center study

Recently, haploidentical transplantations have been performed with unmanipulated BM or PBSC. This approach is becoming more widely adopted with the use of PTCY. However, there is limited evidence about this approach in children. We present 15 children who received 16 haploidentical HSCT with unmanipulated BM or PBSC using PTCY for GVHD prophylaxis. Post-transplant CY(50 mg/kg IV) was given on the third and fifth day, and CsA or tacrolimus with MMF or MP was also used for GVHD prophylaxis. All patients engrafted at a median of 16 and 18 days for neutrophil and thrombocyte recovery, respectively. Grades II-III acute GVHD developed in seven patients, and mild chronic GVHD was found in two patients. Two patients died within the first 100 days due to sepsis (TRM 12.5%). Eleven patients are currently alive, with a median follow-up of 12 months (range 6-22 months). The 12-month OS and DFS were 75 ± 10.8% and 68.8 ± 11.6%, respectively. Our results with these high-risk patients are encouraging for haploidentical HSCT in pediatric patients. Future studies should continue to assess haploidentical HSCT, including comparison of other modalities, in a primary pediatric population.