The following article features coverage from the European Hematology Association (EHA) 2021 Virtual Congress. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Among patients with previously untreated chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL), ibrutinib and venetoclax improved progression-free survival (PFS) compared with chlorambucil plus obinutuzumab, according to research presented at the European Hematology Association (EHA) 2021 Virtual Congress.

Previous research suggests that ibrutinib and venetoclax may combine effectively to inhibit CLL cell proliferation and destroy circulating disease cells. For the randomized phase 3 GLOW study ( Identifier: NCT03462719), researchers compared the safety and efficacy of an ibrutinib/venetoclax combination with that of chlorambucil/obinutuzumab as first-line CLL/SLL treatments.

All enrolled patients were at least 65 years old or were at least 18 years old and had a cumulative illness rating scale score (CIRS) of greater than 6, or creatinine clearance of less than 70 mL/min. No enrolled patients had 17p deletions or TP53 mutations. The primary endpoint was independent review committee-assessed progression-free survival (PFS).

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Overall, 211 patients were enrolled and randomly assigned to receive ibrutinib/venetoclax (106 patients) or chlorambucil/obinutuzumab (105 patients). The median patient age was 71 years, 57.8% of patients were male, and a greater proportion of patients in the ibrutinib/venetoclax group had a CIRS score higher than 6 (69.8% vs 58.1% in the chlorambucil/obinutuzumab group).

The median follow-up was 27.7 months. At this point, the median PFS was superior in the ibrutinib/venetoclax group (hazard ratio, 0.216; P < .0001; median PFS: not reached vs 21 months in the chlorambucil/obinutuzumab group). PFS improvements were seen regardless of CIRS score group and age group.

At 3 months after treatment discontinuation, the undetectable minimal residual disease rate in bone marrow was 51.9% in the ibrutinib/venetoclax group vs 17.1% in the chlorambucil/obinutuzumab group (P < .0001); rates were also improved in peripheral blood (54.7% vs 39%, respectively; P = .0259). Forty-nine of 58 (84.5%) patients in the ibrutinib/venetoclax group maintained these undetectable minimal residual disease rates in peripheral blood until 12 months post-treatment discontinuation.

The tumor lysis syndrome risk decreased for 84.6% of patients in the ibrutinib/venetoclax group.

The most common grade 3 or worse treatment-emergent adverse events included neutropenia/neutrophil count decrease (34.9%), diarrhea (10.4%), and hypertension (7.5%) in the venetoclax/ibrutinib group. Grade 5 adverse events were noted in 7 patients in the venetoclax/ibrutinib group compared with 2 patients in the chlorambucil/obinutuzumab group.

Overall survival data were not mature at the time of analysis.

Disclosure: The presenter declared affiliations with Abbvie, Astra Zeneca, Bristol Myers Squibb, Genmab, Janssen, LAVA, and Roche/Genentech.

Read more of Cancer Therapy Advisor’s coverage of the EHA 2021 Virtual Congress by visiting the conference page.


Kater A, Owen C, Moreno C, et al. Fixed-duration ibrutinib and venetoclax (I+V) versus chlorambucil plus obinutuzumab (Clb+O) for first-line (1l) chronic lymphocytic leukemia (CLL) primary analysis of the phase 3 GLOW study. Paper presented at: European Hematology Association 2021 Virtual Congress; June 2021; Abstract LB1902.