Real-World Evidence on Therapeutic Strategies and Treatment-Sequencing in Patients with Chronic Lymphocytic Leukemia: An International Study of Eric, the European Research Initiative on CLL

The use of novel small molecule inhibitors alone or in combination with anti-CD20 monoclonal antibodies for chronic lymphocytic leukemia (CLL) has raised a number of questions on efficacy, tolerability, long-term treatment adherence in patients with heterogeneous clinical features. To fill this gap, we designed a study focusing on treatment sequencing in patients with CLL in order to (i) compare the outcome of patients treated with chemoimmunotherapy (CIT) combinations in first-line versus those receiving Bruton's tyrosine kinase inhibitors (BTKi); (ii) characterize the efficacy and tolerability of venetoclax-based regimens; (ii) understand the impact of treatment sequencing when it comes to chemo-free options including venetoclax after BTKi and vice versa. Data from consecutive sets of patients diagnosed with CLL between 2000-2020 attended at 77 institutions affiliated with ERIC were collected and analyzed. Collected variables included: demographics, clinical stage at diagnosis, IGHV gene somatic hypermutation status; cytogenetic status for chromosomes 11q, 13q 17p and 12 determined by fluorescence in situ hybridization; TP53 gene mutation status; treatment; treatment response; discontinuation; reason for discontinuation; death. We included 9173 patients with a diagnosis of CLL who received at least one line of treatment. The median age at diagnosis was 67 years with a male:female ratio of 1.9. The median follow-up was 78 months (IQR, 48-120 months). Regarding novel targeted agents, 1860/9173 (20.2%) patients had received at least one line of treatment with BTKi (ibrutinib, n=1788; acalabrutinib, n=72) over the disease course; 631/9173 (6.9%) with venetoclax; and, 447/9173 (4.9%) with the PI3K inhibitor idelalisib. Seventy-nine patients were treated with both BTKi and venetoclax (59 BTKi followed by BCL2i, 20 vice versa). At last follow-up, 5870/9173 patients (64.0%) were alive, 3229/9173 (35.2%) died and 74/9173 (0.8%) were lost to follow-up. Patients treated with BTKi in first-line were enriched for TP53 aberrations [del(17p) 27.6%, TP53 mutation 26.3%] and unmutated IGHV genes (69%) and obtained an ORR of 87.7%. Of these, 136 (26.3%) discontinued treatment after a median of 1.2 years (0.07-5.98); main reasons of discontinuation were toxicity (40.5%) and failure (26.2%). Among 631 patients treated with venetoclax at any line, 100 (15.8%) received BCL2 +/- anti-CD20 as first-line; 170 (26.9%) as second line (125 previously treated with CIT, 27 with BTKi)