Comparison of Classification of Indications for Allogeneic and Autologous Transplant for Adults in ASTCT Guidelines and Evidence Available in Published Literature

Effect of Autograft CD34+ Dose on Outcome in Pediatric Patients Undergoing Autologous Hematopoietic Stem Cell Transplant for Central Nervous System Tumors

Consolidation with autologous hematopoietic stem cell transplantation (HSCT) has improved survival for patients with central nervous system tumors (CNSTs). The impact of the autologous graft CD34+ dose on patient outcomes is unknown. We wanted to analyze the relationship between CD34+ dose, total nucleated cell (TNC) dose, and clinical outcomes, including overall survival (OS), progression-free survival (PFS), relapse, non-relapse mortality (NRM), endothelial-injury complications (EIC), and time to neutrophil engraftment in children undergoing autologous HSCT for CNSTs. A retrospective analysis of the CIBMTR database was performed. Children aged <10 years who underwent autologous HSCT between 2008 to 2018 for an indication of CNST were included. An optimal cut point was identified for patient age, CD34+ cell dose, and TNC, using the maximum likelihood method and PFS as an endpoint. Univariable analysis for PFS, OS, and relapse was described using the Kaplan-Meier estimator. Cox models were fitted for PFS and OS outcomes. Cause-specific hazards models were fitted for relapse and NRM. One hundred fifteen patients met the inclusion criteria. A statistically significant association was identified between autograft CD34+ content and clinical outcomes. Children receiving >3.6×106/kg CD34+ cells experienced superior PFS (p = .04) and OS (p = .04) compared to children receiving ≤3.6 × 106/kg. Relapse rates were lower in patients receiving >3.6 × 106/kg CD34+ cells (p = .05). Higher CD34+ doses were not associated with increased NRM (p = .59). Stratification of CD34+ dose by quartile did not reveal any statistically significant differences between quartiles for 3-year PFS (p = .66), OS (p = .29), risk of relapse (p = .57), or EIC (p = .87). There were no significant differences in patient outcomes based on TNC, and those receiving a TNC >4.4 × 108/kg did not experience superior PFS (p = .26), superior OS (p = .14), reduced risk of relapse (p = .37), or reduced NRM (p = .25). Children with medulloblastoma had superior PFS (p < .001), OS (p = .01), and relapse rates (p = .001) compared to those with other CNS tumor types. Median time to neutrophil engraftment was 10 days versus 12 days in the highest and lowest infused CD34+ quartiles, respectively. For children undergoing autologous HSCT for CNSTs, increasing CD34+ cell dose was associated with significantly improved OS and PFS, and lower relapse rates, without increased NRM or EICs.

Strong Cellular Immune Response, but Not Humoral, against SARS-CoV-2 in Oncohematological Patients with Autologous Stem Cell Transplantation after Natural Infection

Oncohematological patients show a low immune response against SARS-CoV-2, both to natural infection and after vaccination. Most studies are focused on the analysis of the humoral response; therefore, the information available about the cellular immune response is limited. In this study, we analyzed the humoral and cellular immune responses in nine individuals who received chemotherapy for their oncohematological diseases, as well as consolidation with autologous stem cell transplantation (ASCT), after being naturally infected with SARS-CoV-2. All individuals had asymptomatic or mild COVID-19 and were not vaccinated against SARS-CoV-2. These results were compared with matched healthy individuals who also had mild COVID-19. The humoral response against SARS-CoV-2 was not detected in 6 of 9 oncohematological individuals prior to ASCT. The levels of antibodies and their neutralization capacity decreased after ASCT. Conversely, an enhanced cytotoxic activity against SARS-CoV-2-infected cells was observed after chemotherapy plus ASCT, mostly based on high levels of NK, NKT, and CD8+TCRγδ+ cell populations that were able to produce IFNγ and TNFα. These results highlight the importance of performing analyses not only to evaluate the levels of IgGs against SARS-CoV-2, but also to determine the quality of the cellular immune response developed during the immune reconstitution after ASCT.