Incidence, Management, and Prognosis of Graft Failure and Autologous Reconstitution after Allogeneic Hematopoietic Stem Cell Transplantation

Graft failure after allogeneic hematopoietic stem cell transplantation in pediatric patients with acute leukemia: autologous reconstitution or second transplant?

BACKGROUND

Graft failure (GF) is a rare but serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Prevention of graft failure remains the most advisable approach as there is no clear recommendation for the best strategies for reversing this complication. Administration of growth factor, additional hematopoietic progenitor boost, or a salvage HSCT are current modalities recommended for the treatment of GF. Autologous recovery without evidence of disease relapse occurs rarely in patients with GF, and in the absence of autologous recovery, further salvage transplantation following a second conditioning regimen is a potential treatment option that offers the best chances of long-term disease-free survival. The preconditioning regimens of second HSCT have a significant impact on engraftment and outcome, however, currently there is no consensus on optimal conditioning regimen for second HSCT in patients who have developed GF. Furthermore, a second transplant from a different donor or the same donor is still a matter of debate.

OBSERVATIONS

We present our experience in managing pediatric patients with acute leukemia who encountered graft failure following stem cell transplantation.

CONCLUSIONS AND RELEVANCE

Although a second transplantation is almost the only salvage method, we illustrate that some pediatric patients with acute leukemia who experience graft failure after an allogeneic stem cell transplant using Myeloablative conditioning (MAC) regimen may achieve long-term disease-free survival through autologous hematopoiesis recovery.

Autologous hematopoietic recovery after allogeneic hematopoietic stem cell transplantation: A case-based review

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely applied for the treatment of hematologic malignancies, but autologous hematopoietic recovery (AR) after allo-HSCT is rare clinically, especially after myeloablative conditioning (MAC). The mechanism of AR remains unclear so far, but the prognosis for most patients is relatively good. Second transplantation is preferred after disease relapse. Starting from a real-life clinical case scenario, herein we reviewed some of the crucial issues of AR in light of recent refinements, and discussed our patients based on the current evidence.

Long-term outcome of second allogeneic hematopoietic stem cell transplantation (HSCT2) for primary graft failure in patients with acute leukemia in remission: A study on behalf of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation

Second transplantation (HSCT2) is a potential treatment for primary graft failure (pGF). We assessed the outcome of HSCT2, performed between 2000 and 2021, for pGF in 243 patients with acute leukemia. Median age was 44.8 years. Conditioning at first HSCT (HSCT1) was myeloablative (MAC) in 58.4%. Median time from HSCT1 to HSCT2 was 48 days. Donors for HSCT2 were the same as for HSCT1 in 49%. Engraftment post HSCT2 was achieved by 73.7% of patients. The incidence of acute (a) graft versus host disease (GVHD) grades II-IV and III-IV was 23.2 and 8.1%. 5-year total and extensive chronic (c) GVHD was 22.3 and 10.1%. 5-year nonrelapse mortality (NRM), relapse incidence (RI), leukemia-free survival (LFS), overall survival (OS) and GVHD free, relapse-free survival (GRFS) was 51.6, 18.8, 29.6, 30.7 and 22.4%, respectively. Infections were the main cause of death. In multivariable analysis, being transplanted at second vs. first remission, lower Karnofsky performance status (KPS; <90) and receiving MAC at HSCT1 were adverse prognostic factors for NRM, LFS, OS, and GRFS, as was increased age for NRM, LFS, OS. We conclude that HSCT2 can rescue about a third of the patients who experienced pGF, but NRM is as high as 50%.

PD-L1's Role in Preventing Alloreactive T Cell Responses Following Hematopoietic and Organ Transplant

Over the past decade, Programmed Death-Ligand 1 (PD-L1) has emerged as a prominent target for cancer immunotherapies. However, its potential as an immunosuppressive therapy has been limited. In this review, we present the immunological basis of graft rejection and graft-versus-host disease (GVHD), followed by a summary of biologically relevant molecular interactions of both PD-L1 and Programmed Cell Death Protein 1 (PD-1). Finally, we present a translational perspective on how PD-L1 can interrupt alloreactive-driven processes to increase immune tolerance. Unlike most current therapies that block PD-L1 and/or its interaction with PD-1, this review focuses on how upregulation or reversed sequestration of this ligand may reduce autoimmunity, ameliorate GVHD, and enhance graft survival following organ transplant.

The Development of New Agents for Post-Hematopoietic Stem Cell Transplantation Non-Infectious Complications in Children

Hematopoietic stem cell transplantation (HSCT) is often the only curative treatment option for patients suffering from various types of malignant diseases and some non-cancerous conditions. Nevertheless, it is associated with a high risk of complications leading to transplant-related mortality and long-term morbidity. An increasing number of therapeutic and prevention strategies have been developed over the last few years to tackle the complications arising in patients receiving an HSCT. These strategies have been mainly carried out in adults and some are now being translated into children. In this manuscript, we review the recent advancements in the development and implementation of treatment options for post-HSCT non-infectious complications in pediatric patients with leukemia and other non-malignant conditions, with a special attention on the new agents available within clinical trials. We focused on the following conditions: graft failure, prevention of relapse and early interventions after detection of minimal residual disease positivity following HSCT in acute lymphoblastic and myeloid leukemia, chronic graft versus host disease, non-infectious pulmonary complications, and complications of endothelial origin.