Hematopoietic stem cell boost for persistent neutropenia after CAR T-cell therapy: a GLA/DRST study

Hematotoxicity after chimeric antigen receptor (CAR) T-cell therapy is associated with infection and death but management remains unclear. We report results of 31 patients receiving hematopoietic stem cell boost (HSCB; 30 autologous, 1 allogeneic) for either sustained severe neutropenia of grade 4 (<0.5 x 109/L), sustained moderate neutropenia (<= 1.5 x 109/L) and high risk of infection, or neutrophil count <= 2.0 x 109/L and active infection. Median time from CAR T-cell therapy to HSCB was 43 days and median absolute neutrophil count at time of HSCB was 0.2. Median duration of neutropenia before HSCB was 38 days (range, 7-151). Overall neutrophil response rate (recovery or improvement) was observed in 26 patients (84%) within a median of 9 days (95% confidence interval, 7-14). Time to response was significantly associated with the duration of prior neutropenia (P = .007). All nonresponders died within the first year after HSCB. One-year overall survival for all patients was 59% and significantly different for neutropenia (<= 38 days; 85%) vs neutropenia >38 days before HSCB (44%; P = .029). In conclusion, early or prophylactic HSCB showed quick response and improved outcomes for sustained moderate to severe neutropenia after CAR-T.

Automated summary

Hematotoxicity after CAR-T therapy can be managed with hematopoietic stem cell boost (HSCB), which showed a quick response and improved outcomes for sustained moderate to severe neutropenia. 31 patients received HSCB, with an overall neutrophil response rate of 84% and a median response time of 9 days. Patients with shorter duration of neutropenia had significantly better survival outcomes compared to those with longer duration. The 1-year overall survival rate was 59%.