The Use of Ibrutinib in Italian CLL Patients Treated in a Real-World Setting (EVIDENCE): A Preliminary Report

Introduction

Ibrutinib is the only once-daily Bruton's tyrosine kinase (BTK) inhibitor with significant survival benefit vs chemo- and /or immunotherapy in multiple phase 3 studies of patients (pts) with chronic lymphocytic leukemia (CLL). It has profoundly changed the treatment landscape of CLL with the longest follow-up. However, seven years (yrs) after ibrutinib was approved in Italy by regulatory agencies for CLL treatment, available data on the patterns of care of such pts in the setting of clinical practice is limited.

Herein we present the first interim analysis (IA) of EVIdeNCE (ClinicalTrials.gov Identifier: NCT03720561), a multicenter, observational clinical study designed to describe the current management of pts receiving ibrutinib in real-world setting in Italy in terms of retention rate: the study's primary end point.

Methods

EVIDENCE 312 treatment-naïve (TN) 38% and relapsed/refractory (R/R) 62% pts with CLL according to the iwCLL diagnosis criteria observed at 39 Italian hematological institutions in the period between November 2018 and October 2019. Inclusion criteria were treatment with ibrutinib according to the European Summary of Product Characteristics as per routine clinical practice started within the previous 3 months. The purpose of this IA is to provide demographics and disease characteristics at baseline and a preliminary evaluation of ibrutinib retention rate after one year of follow-up, along with its safety profile.

Results

The median age of pts at the time of ibrutinib initiation was 71.0 yrs (range 41.0-89.0), with 60% ≥70 yrs, 63.2% male, and 90% with Eastern Cooperative Oncology Group (ECOG) performance 0-1. Baseline Rai stage 0-I, II, and III-IV accounted for 18.3%, 29.7% and 52.1% pts, respectively. Patients in stage IV were observed in 40% of the R/R and 27% in TN subgroup. Considering 120 pts with known mutational status, del(17p) and/or TP53 mutation were present in 50.0% of pts (TN=52.1%, R/R=48.6%), while IGHV was unmutated in 35.0% (TN=33.3% and R/R=36.15) and mutated in 15.0% (TN=14.6%, R/R=15.3%). At baseline, 62.9% of pts had comorbidities and 30.6% presented with a history of cardiovascular diseases (CVDs). A CIRS score ≥6 was observed in 28.5% of pts. The median time from CLL diagnosis to the start of ibrutinib was 5.1 yrs (TN 1.75 yrs vs R/R 7.27 yrs).

At least 1 treatment-emergent adverse event (TEAE) of any grade was experienced by 70.7% of pts. Frequencies were as follows: infections (30.8%; COVID-19 infections 3.2%), arthralgia (10.8%), neutropenia (9.3%), fatigue (8.4%), diarrhea (7.7%), atrial fibrillation (7.4%; grade 3-4, 4.2%), fever (7.1%), rash (6.4%), anemia (6.1%) and hypertension (4.2%). Mild bleeding TEAEs were reported in 16.1% of pts with no major bleeding event. TEAEs were more frequent in the elderly (≥65 yrs) while no significant differences in the rate of TEAEs were recorded in TN and R/R pts (69.7% vs 71.4%, respectively). Serious TEAEs were reported in 21.9% of pts.

Overall in intention to treat (ITT), 32 deaths (10%) were observed (TN=8, R/R=24). The most common causes of death were infections (3.5%) and progressive disease (PD) (1.9%).

Permanent discontinuation was observed in 56 (18%) of the pts (TN=17.2%, R/R=18.7%) and it mostly occurred within the first 6 months. Main causes of discontinuation were toxicity (6.1%), PD (3.8%) or death (3.5%). Temporary interruptions (≤ 3 months without therapy and/or dose modifications) during the whole observation period occurred in 30.3% (TN=35.3%, R/R=27.2%) and 37.7% (TN=37.5%, R/R=37.8%) of pts, respectively, mainly determined by toxicity and clinical judgment.

Finally, in this first IA after 17.3 months (range 1.1 - 27.0) median follow-up, the ibrutinib retention rate (calculated as the ratio between the number of patients who retained ibrutinib treatment over the total number of patients at risk) at 1-year was 81.9% [95% confidence interval (CI), 77.2% - 86.1%] with no difference between TN 83.2% (95% CI, 75.2% - 89.4%) and R/R 81.2% pts (95% CI, 74.9% - 86.4%).

Conclusions

EVIDENCE is the first real-world study of ibrutinib use in CLL clinical practice in Italy. Ibrutinib retention rate at one-year suggests a better knowledge and expertise of hematologists in the management of ibrutinib-related toxicities that may result in an improved long-term outcome of pts with CLL.