Frequency and outcomes of obinutuzumab-induced thrombocytopenia

Obinutuzumab is a third-generation anti-CD20 monoclonal antibody widely used in the treatment of B-lymphoproliferative disorders but infrequently associated with severe thrombocytopenia, which can be life-threatening. The pathophysiology is unclear, but platelet clearance can be extremely rapid (usually within 24 h). In a retrospective case series, we have identified four cases among 149 recipients of obinutuzumab-containing chemotherapy regimens between 2015 and 2022 treated for haematological malignancies in Canberra, Australia (frequency 2.7%). We illustrate four cases of obinutuzumab-induced thrombocytopenia with a review of the literature. Research is required to identify the pathophysiology and improve early recognition and management of the condition in the context of multiagent chemotherapy.