Incidence, duration, and severity of neutropenia in adults with B-cell acute lymphoblastic leukemia receiving blinatumomab consolidation.

Blinatumomab is a CD3 × CD19 antibody approved for adults with B-cell acute lymphoblastic leukemia (B-ALL). Blinatumomab is not considered myelosuppressive, but significant neutropenia has been seen in practice. We reviewed 95 patients with B-ALL who received blinatumomab at Dana-Farber Cancer Institute between 2015 and 2024. Of these, 71 patients were treated in morphologic remission with absolute neutrophil count (ANC) ≥1 × 109/L, for which 41% experienced grade ≥3 neutropenia and 13% developed ANC <0.1 × 109/L during blinatumomab. Neutropenia occurred more frequently during cycle 2 than cycle 1, and neutropenia did not necessarily portend worse neutropenia in later cycles. Multivariable analysis did not identify concurrent tyrosine kinase inhibitor use as a significant covariate for neutropenia. The nine patients who experienced ANC <0.1 × 109/L did not develop serious infections and received supportive care. Neutropenia occurs frequently and may be severe in patients with B-ALL who receive blinatumomab during remission, but complications appear manageable.