[Clinical analysis of autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation in thalassemia major]

HSCT remains the only cure for patients with transfusion-dependent thalassemia until gene therapy strategies are proven to be safe

Patients with β-thalassemia suffer from severe anemia, iron overload and multiple complications, that affect their quality of life and well-being. Allogeneic hematopoietic stem cell transplantation (HSCT) from an HLA-matched sibling donor, performed in childhood, has been the gold standard for thalassemic patients for decades. Unfortunately, siblings are available only for the minority of patients. Fully matched unrelated donors have been the second choice for cure, with equal results as far as overall survival is concerned, having though the cost of frequent and serious complications. On the other hand, haploidentical transplantation is performed more frequently during the last decade, with promising results. Gene therapy represents a novel therapeutic approach, with impressive results from clinical trials, both from gene addition strategies, as well as from the emerging gene editing tools. After reviewing current critical points of HSCT using alternative donors and assessing recently reported safety issues of gene therapy methods, we conclude that, although a breakthrough, the safety of gene therapy remains to be established.

Refractory autoimmune haemolytic anaemia following allogenic haematopoietic stem cell transplantation: successful treatment of rituximab

Objective

To investigate the effectiveness and safety of rituximab in treating autoimmune haemolytic anaemia (AIHA) after allogeneic haematopoietic stem cell transplantation (allo-HSCT).

Methods

Patients with refractory AIHA following allo-HSCT were treated once-weekly with rituximab 375 mg/m² for a total of four doses. In an animal study, recipient CB6F1 mice were conditioned with busulfan/fludarabine and transplanted with splenocytes and T-cell-depleted bone marrow from C57Bl/6 mice. In this animal model, anti-CD20 monoclonal antibody (mAb) was evaluated to see if it could prevent graft versus host disease (GVHD). GVHD was monitored by body weight loss, GVHD clinical scores and the survival of each group of mice. Histopathological analyses of the skin, intestine, liver and lung were used to analyse the severity of GVHD.

Results

After rituximab therapy, refractory AIHA was resolved in all four patients as shown by increased haemoglobin levels. B-cell proportions were reduced with a relative increase of the proportions of T-cells following rituximab treatment. None of the four patients experienced chronic GVHD. In the animal model, anti-CD20 mAb treatment reduced GVHD.

Conclusions

Rituximab therapy deserves consideration for the treatment of post-HSCT patients with refractory AIHA. Further studies are needed to define the therapeutic role of this anti-CD20 mAb.