Uniform conditioning regardless of donor in bone marrow transplantation for severe aplastic anemia

Protective factors, management and prognosis of mixed chimerism after allogeneic hematopoietic stem cell transplantation for severe aplastic anemia in children

Mixed chimerism (MC) frequently arises in children with severe aplastic anemia (SAA) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nonetheless, there is a paucity of research regarding potential predictors and effective interventions. This retrospective study, performed on 150 pediatric patients with SAA who underwent allo-HSCT between December 2015 and June 2022, explored the characteristics, risk factors, treatment, and prognosis of MC. A total of 29 patients (19.3%) developed MC following allo-HSCT, with two individuals experiencing MC twice. The CTX + ATG regimen was associated with the development of MC. Peripheral blood (PB) + bone marrow (BM) stem cell graft and a high number of CD34+ cells were identified as independent protective factors for MC. The cumulative incidence of grade II-IV acute graft-versus-host disease was significantly elevated in donor chimerism (DC) relative to MC. Among MC patients with cytopenia, only two patients who received increased immunosuppression alone were effective. Complete DC was achieved in all four patients who received the second transplantation. In conclusion, we emphasize that prompt second transplantation is essential when cellular therapy and enhanced immunosuppression fail for MC patients with cytopenia.

Measuring Patient Preferences to Inform Clinical Trial Design: An Example in Rheumatoid Arthritis

BACKGROUND

Allogeneic bone marrow transplantation (BMT) may be a curative treatment for patients with rheumatoid arthritis (RA), but it has serious risks, including death. It is uncertain whether patients would accept the risks and benefits of BMT and participate in clinical trials. We conducted a discrete choice experiment (DCE) to quantify risk tolerance and benefit-risk trade-offs to inform the design of a clinical trial for BMT.

METHODS

We conducted a DCE with three attributes (three levels each): chance of stopping disease progression (50-90%), increased chance of death in year after transplant (3-15%), and chance of chronic graft-versus-host disease (cGVHD) (3-15%). An orthogonal main effects design of nine binary choice tasks were presented for two scenarios: one considering their current situation and a second scenario where the patient has failed seven anti-rheumatic drugs. Participants were recruited from the Rheum4U inflammatory arthritis registry. Choice data were analyzed using a logit model accounting for multiple responses per participant.

RESULTS

Sixty patients participated. Most (82%) had severe disease, and the median number of anti-rheumatic drugs previously taken was 6 (range 0-18). As expected, an increased chance of stopping disease progression increases the probability of choosing BMT, while increased chance of both risks decreases the probability. Patients were willing to accept a 3% increase in risk of death or 6% increase in chance of chronic GVHD for a 10% increase in the chance of stopping disease progression. For the most clinically likely BMT risk-benefit profiles, and the likely initial target population of patients who have failed multiple biologics, between 72% and 91% of patients would choose BMT.

CONCLUSIONS

Patients with RA are willing to accept substantial risks for a chance to stop disease progression with BMT, suggesting that a pilot trial of BMT for RA could successfully recruit patients. Preference studies have an important role in informing patient-centered clinical trial planning and design.

Allogeneic Hematopoietic Cell Transplantation for the Treatment of Severe Aplastic Anemia: Evidence-Based Guidelines From the American Society for Transplantation and Cellular Therapy

Allogeneic hematopoietic cell transplantation (HCT) is a potentially curative treatment for severe aplastic anemia (SAA). Existing guidance about HCT in SAA is primarily derived from expert reviews, registry data and societal guidelines; however, transplant-specific guidelines for SAA are lacking. A panel of SAA experts, both pediatric and adult transplant physicians, developed consensus recommendations using Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology employing a GRADE guideline development tool. The panel agrees with previous recommendations for the preferential use of bone marrow as a graft source and the use of rabbit over horse antithymocyte globulin (ATG) for HCT conditioning. Fludarabine containing regimens are preferred for patients at high risk of graft failure and those receiving matched unrelated or haploidentical donor transplant. Given advancements in HCT, the panel does not endorse the historical 40-year age cut-off for considering upfront HCT in adults, acknowledging that fit older patients may also benefit from HCT. The panel also endorses increased utilization of HCT by prioritizing matched unrelated or haploidentical donor HCT over immunosuppressive therapy in children and adults who lack a matched related donor. Finally, the panel suggests either calcineurin inhibitor plus methotrexate or post-transplant cyclophosphamide-based graft-versus-host disease (GVHD) prophylaxis for matched related or matched unrelated donor recipients. These recommendations reflect a significant advancement in transplant strategies for SAA and highlight the importance of ongoing and further research to revisit current evidence in terms of donor choice, conditioning chemotherapy, GVHD prophylaxis and post-transplant immunosuppression.

Modified Delphi panel consensus recommendations for management of severe aplastic anemia

ABSTRACT

Severe aplastic anemia (SAA) is a rare hematologic condition for which there is no clear management algorithm. A panel of 11 experts on adult and pediatric aplastic anemia was assembled and, using the RAND/University of California, Los Angeles modified Delphi panel method, evaluated >600 varying patient care scenarios to develop clinical recommendations for the initial and subsequent management of patients of all ages with SAA. Here, we present the panel's recommendations to rule out inherited bone marrow failure syndromes, on supportive care before and during first-line therapy, and on first-line (initial management) and second-line (subsequent management) therapy of acquired SAA, focusing on when transplant vs medical therapy is most appropriate. These recommendations represent the consensus of 11 experts informed by published literature and experience. They are intended only as general guidance for experienced clinicians who treat patients with SAA and are in no way intended to supersede individual physician and patient decision making. Current and future research should validate this consensus using clinical data. Once validated, we hope these expert panel recommendations will improve outcomes for patients with SAA.

Diagnostic evaluation in bone marrow failure disorders: what have we learnt to help inform the transplant decision in 2024 and beyond?

Aplastic anemia (AA) is the prototypical bone marrow failure syndrome. In the current era of readily available 'molecular annotation', application of comprehensive next-generation sequencing panels has generated novel insights into underlying pathogenetic mechanisms, potentially leading to improvements in personalized therapeutic approaches. New evidence has emerged as to the role of somatic loss of HLA class I allele expression in 'immune-mediated' AA, associated molecular aberrations, and risk of clonal evolution. A deeper understanding has emerged regarding the role of 'myeloid' gene mutations in this context, translating patho-mechanistic insights derived from wider clinical and translational research within the myeloid disorder arena. Here, we review contemporary 'tools' which aid in confirmation of a diagnosis of AA, with an additional focus on their potential in guiding therapeutic options. A specific emphasis is placed upon interpretation and integration of this detailed diagnostic information and how this may inform optimal transplantation strategies.