SARS-CoV-2-specific T cells are generated in less than half of allogeneic HSCT recipients failing to seroconvert after COVID-19 vaccination.

Little is known about the cellular immune response to SARS-CoV-2 vaccination in patients after HSCT and B-NHL with iatrogenic B-cell aplasia. In nonseroconverted HSCT patients, induction of specific T-cell responses was assessed. The majority of allogeneic HSCT patients not showing humoral responses to vaccination also fail to mount antigen-specific T-cell responses.

Long-Term Remission of Acquired Von-Willebrand's Disease and Platelet Dysfunction after High-Dose Melphalan in a Patient with Multiple Myeloma.

Background: Autologous stem cell transplantation is considered a standard of care treatment in eligible patients with multiple myeloma, but puts the patient at high risk for infections and bleeding complications. Acquired von-Willebrand's disease (AVWD) and acquired platelet dysfunction are rare bleeding disorders that are associated with lymphoproliferative disorders such as multiple myeloma. Patients with acquired bleeding disorders who are planned for ASCT to treat the underlying condition are considered at highest risk for bleeding complications, and optimal treatment strategies are not known. Materials and Methods: We summarized the diagnostic and therapeutic approach to a patient affected by AVWD and acquired platelet disorder related to multiple myeloma. The patient who was planned for ASCT presented with moderate to severe bleeding symptoms. Results: Acute bleeding episodes were successfully controlled and prevented during induction and consolidation therapy with immunoglobulins, whereas replacement of plasma-derived VW factor showed no clinical improvement. High-dose melphalan-based consolidation therapy supported with autologous stem-cell transplantation led to an immediate and sustainable rise of von-Willebrand antigen and activity and a subsequent normalization of platelet aggregation activity. After a follow-up of 40 weeks, the patient maintained normalized VW levels and platelet aggregation capacity. There were no further signs or symptoms of bleeding. Conclusion: This case report highlights the necessity for combined supportive and causal treatment in patients with AVWD and paraproteinemic PD. High-dose melphalan with autologous stem cell support may function as a treatment option in patients with myeloma-related AVWD.

Functional Dominance of CHIP-Mutated Hematopoietic Stem Cells in Patients Undergoing Autologous Transplantation.

Clonal hematopoiesis of indeterminate potential (CHIP) is caused by recurrent somatic mutations leading to clonal blood cell expansion. However, direct evidence of the fitness of CHIP-mutated human hematopoietic stem cells (HSCs) in blood reconstitution is lacking. Because myeloablative treatment and transplantation enforce stress on HSCs, we followed 81 patients with solid tumors or lymphoid diseases undergoing autologous stem cell transplantation (ASCT) for the development of CHIP. We found a high incidence of CHIP (22%) after ASCT with a high mean variant allele frequency (VAF) of 10.7%. Most mutations were already present in the graft, albeit at lower VAFs, demonstrating a selective reconstitution advantage of mutated HSCs after ASCT. However, patients with CHIP mutations in DNA-damage response genes showed delayed neutrophil reconstitution. Thus, CHIP-mutated stem and progenitor cells largely gain on clone size upon ASCT-related blood reconstitution, leading to an increased future risk of CHIP-associated complications.