Treatment With the Combination of Rituximab and Intravenous γ Globulin Is Effective in Promoting Engraftment in Donor-Specific Antibody Positive Patients Receiving Myeloablative Conditioning Haploidentical Stem Cell Transplantation.

Donor-specific anti-HLA antibodies (DSAs) are a major cause of engraftment failure in patients receiving haploidentical stem cell transplantation (HaploSCT). Effective procedures are needed for those who demand urgent transplantation and have no other donor options. We here retrospectively analyzed 13 patients with DSAs successfully treated with desensitization of rituximab and intravenous γ globulin (IVIg) before HaploSCT from March 2017 to July 2022. All 13 patients had DSA mean fluorescence intensity >4000 of at least 1 loci before desensitization. Of the 13 patients, 10 patients were with the initial diagnosis of malignant hematological diseases, and 3 were diagnosed with aplastic anemia. Patients were treated with 1 (n = 3) or 2 (n = 10) doses of rituximab (375 mg/m for 1 dose). All patients receive the same total dose of 0.4 g/kg of IVIg within 72 hours before haploidentical stem cell administration to neutralize the remaining DSA. All patients achieved neutrophil engraftment, and 12 patients achieved primary platelet engraftment. The patient with primary platelet engraftment failure received purified CD34-positive stem cell infusion nearly 1 year after transplantation and achieved platelet engraftment thereafter. The estimated 3-year overall survival is 73.4%. Although further studies on larger numbers of patients are needed, it is clear that the combination of IVIg and rituximab is an effective way to clear DSA and has a strong effect on promoting engraftment and survival for patients with DSA. It is a practical and adaptable combination of treatment options.