Phase III GLOW trial: Ibrutinib plus venetoclax in previously untreated CLL/SLL

Pavlovsky then discussed the 4-year follow-up data for the GLOW trial. Fixed-duration ibrutinib + venetoclax continued to significantly improve PFS, with estimated 3.5-year PFS rates of 74.6% for the ibrutinib + venetoclax cohort and 24.8% for the chlorambucil + obinutuzumab cohort. Pavlovsky noted that MRD status had a low impact on PFS. 4-year PFS was significantly longer for patients treated with ibrutinib + venetoclax compared with those receiving chlorambucil + obinutuzumab (HR, 0.214; 95% CI, 0.138−0.334; p < 0.001), and the observed improvement in PFS with ibrutinib + venetoclax was consistent across subgroups such as older patients and those with comorbidities, as well as stratification factors such as IGHV mutational status. The detailed 4-year outcomes were recently published on the Lymphoma Hub.

Furthermore, Pavlovsky discussed the safety data from the GLOW trial. Adverse events of Grade ≥3 occurred for 75.5% and 69.5% of patients treated with ibrutinib + venetoclax and chlorambucil + obinutuzumab, respectively, with neutropenia being most common in both arms at 34.9% and 49.5%, respectively. There were 11 and 12 all-cause deaths in the ibrutinib + venetoclax and chlorambucil + obinutuzumab arms, respectively. 

Pavlovsky concluded that, overall, oral, once-daily, fixed-duration ibrutinib + venetoclax provided deeper, longer, and more sustained responses in the GLOW trial vs chlorambucil + obinutuzumab, significantly extending PFS in older patients with previously untreated CLL/SLL and comorbidities. 

This presentation was followed by a panel discussion between Pavlovsky, Gilles Salles, Martin Dreyling, Stefano Luminari, Ulrich Jӓger, and Francesc Bosch, covering the following questions:  

Pavlovsky reviewed the GLOW trial results, other fixed-duration regimens, and BTK inhibitor / BCL21 combinations, and the panel debated the practicalities of incorporating fixed-duration ibrutinib + venetoclax as a treatment regimen for previously untreated patients with CLL/SLL. The panel commented that the GLOW trial outcomes reinforce the concept of time-limited therapy for unfit patients. The utility of fixed-duration ibrutinib + venetoclax in older vs younger populations was discussed, and its potential to reduce hospital admissions was noted. The panel emphasized the need for cardiac monitoring with the combination. They also discussed the timing of MRD assessment and the importance of mutational status when deciding between ibrutinib + venetoclax and obinutuzumab + venetoclax. Lastly, it was noted that the ibrutinib + venetoclax regimen is not currently approved in the US. 

Supported by an educational grant from Janssen Biotech, Inc., administered by Janssen Scientific Affairs, LLC. All content is developed by SES in collaboration with an expert steering committee; funders are allowed no influence on the content of this resource.