Background Obinutuzumab is an anti-CD20 monoclonal antibody approved in combination with chlorambucil for patients with chronic lymphocytic leukaemia (CLL) and comorbidities, making them unsuitable for full-dose fludarabine-based therapy.

Purpose To analyse the safety and effectiveness of obinutuzumab combined with chlorambucil as first-line treatment in our hospital.

Material and methods Observational, retrospective, descriptive study. Inclusion criteria: adults (>18 years) that initiate treatment with obinutuzumab-chlorambucil. Study period: January 2017 to September 2018. Demographic variables: gender, age; clinical variables: diagnose and cumulative illness rating scale (CIRS); and therapy-related: adverse events and suspension. Safety was evaluated in all patients that received at least one obinutuzumab dose by analysing adverse events (AE) from clinical records, treatment delays and/or concomitant medication required. AE are classified following the 5.0 version of National Institute Cancer: Common Terminology Criteria for Adverse Events. Effectiveness was evaluated following International Workshop CLL; Halleck 2008 criteria a minimum of 3 months after the end of treatment.

Results Seven patients were included (four male and three female), median age: 72 years (rank 67–82). Median CIRS punctuation: 9 (rank 6–11). All patients received premedication with corticosteroids, antipyretic and antihistaminic to avoid infusion-related reactions (IRRs) and allopurinol as prophylaxis for tumour lysis syndrome.

During the first infusion, two patients presented hypertension, abdominal pain and cold as grade 1–2 IRRs requiring temporary interruption. IRRs were not recorded in the following perfusions.

Four patients presented haematologic toxicity, grade 3 neutropenia, requiring G-CSF, treatment delay was only required in one of them.

Other AE: grade 2 anaemia treated with erythropoietin (n=1), grade 2 thrombocytopenia (n=1), respiratory infections (n=2; one patient with hypogammaglobulinaemia previous to treatment required hospital admission and treatment suspension).

By the time the study was finished, effectiveness was evaluated in four up to six patients that finished treatment: complete response (n=3) and partial response (n=1).

Conclusion In our experience, the obinuzumab-chlorambucil scheme presented a good safety profile in patients with comorbidities. The main AE were IRRs: limited to first administration that did not require treatment suspension; and neutropaenia, which was the most frequent haematologic toxicity.

Regarding response, a continuous monitoring is necessary to confirm long-term effectiveness.

References and/or acknowledgements No conflict of interest.