First-line ibrutinib-venetoclax in chronic lymphocytic leukemia: GLOW 67-month results and grade 3/4 adverse event-free progression-free survival

Long-term efficacy and toxicity data are needed to inform optimal first-line treatment for individual patients with chronic lymphocytic leukemia (CLL). We report long-term outcomes of ibrutinib-venetoclax in older/comorbid patients at 67-month median follow-up of the phase III GLOW study (NCT03462719) and report grade 3/4 treatment-emergent adverse event (TEAE)-free progression-free survival (PFS). Patients were randomized 1:1 to ibrutinib-venetoclax ( n = 106) or chlorambucil-obinutuzumab ( n = 105). Sixty-six-month overall survival (OS) rates were 79.0% and 60.8% for ibrutinib-venetoclax and chlorambucil-obinutuzumab, respectively (hazard ratio [HR] 0.46). Ibrutinib-venetoclax reduced the risk of requiring second-line therapy by 77.4% and continued to improve PFS vs chlorambucil-obinutuzumab (66-month rates: 51.7% vs 18.1%, HR 0.27), regardless of IGHV/measurable residual disease (MRD) status. Ibrutinib-venetoclax-treated patients with undetectable MRD at end-of-treatment had better PFS outcomes than those with detectable MRD, especially in patients with unmutated IGHV. Grade 3/4 TEAE-free PFS was 21.4 months longer for ibrutinib-venetoclax vs chlorambucil-obinutuzumab (51.6 vs 30.2 months). Ibrutinib-venetoclax maintains superior OS, superior PFS, reduction in need for second-line treatment, and longer PFS duration without grade 3/4 TEAEs vs chlorambucil-obinutuzumab. Fixed-duration ibrutinib-venetoclax is an effective first-line treatment option for older/comorbid patients with previously untreated CLL, providing durable disease control and preserving future treatment options.