Background and Importance The usual oral dosage of ibrutinib in chronic lymphatic leukaemia (CLL) is 420 mg every 24h. However, comorbidities, adverse effects and drug interactions require a dose reduction (DR), and the efficacy of treatment may be compromised.

Aim and Objectives To analyse the reasons of ibrutinib dose reduction and its consequences on disease progression/death.

Material and Methods Retrospective observational study that includes patients (n=60) diagnosed with CLL treated with ibrutinib between 09/16/2020-09/16/2022 and not involved in a clinical trial. The demographic characteristics of patients were the following: 43 males (72%), mean age 72.9 years (53-89).

Data collection include DR requirements, DR reasons, treatment suspensions, disease progression and death with their respective date recording.

The percentage of patients requiring DR and the reason thereof were calculated. Percentage of disease progression and death also. In addition, median treatment durations were calculated in months and expressed in percentages; overall median duration (OMD) and after DR requirement (DRMD).

The data was obtained from the electronic medical record (Osabide Global) and the electronic prescription program (Onkobide).

Results 35% of patients (n=21) required DR during the study period. The main reasons for DR were toxicity 76,1% (n=16), pharmacological interactions 9,5% (n=2), efficacy 4,8% (n=1), aging 4,8% (n=1) and patient decision 4,8% (n=1). 10% of DR patients (n=2) suffered CCL progression and 29% (n=6) died. 5% (n=2) of patients non-requiring DR suffered CCL progression and 13% (n=5) died. The OMD of the treatment was 17 months (0-73) and the DRMD was 12 months (0-70).

Conclusion and Relevance The ibrutinib DR does not influence the disease progression or mortality, although the sample size is not enough for a formal statistical analysis. Toxicity was identified as the most common reason for DR. The OMD and DAMD data presented in this work are lower than those commonly published in the literature (1) due to the technical limitations on the software systems.

Reference

1. Hardy-Abeloos C, Pinottiand R, Gabrilove J, Ibrutinib dose modifications in the management of CLL. Journal of Hematology and Oncology 2020;13:66 Available: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7275592/pdf/13045_2020_Article_870.pdf

Conflict of Interest No conflict of interest