For patients with high-risk chronic lymphocytic leukemia (CLL), first-line therapy with a triple combination of targeted agents showed encouraging response rates in the phase 2.
Among 41 patients with untreated CLL bearing deleterious TP53 mutations and/or the 17p chromosomal deletion who received the GIVe regimen consisting of obinutuzumab (Gazyva), ibrutinib (Imbruvica), and venetoclax (Venclexta), the complete response rate at final restaging was 58.5%, and 33 patients with a confirmed response were negative for minimal residual disease after a median follow-up of 18.6 months, reported Henriette Huber, MD, of University Hospital Ulm, Germany.
“The GIVe regimen is promising first-line therapy for patients with high-risk CLL,” she said in a presentation during the virtual annual congress of the European Hematology Association.
The overall safety profile of the combination was acceptable, she said, but added that “some higher-grade infections are of concern.” The rate of grade 3 or greater infections/infestations in the study was 19.5%.
Sound rationale (with caveat)
Another adverse event of concern is the rate of atrial fibrillation in the comparatively young patient population (median age 62), noted Alexey Danilov, MD, PhD, of City of Hope in Duarte Calif., who commented on the study for MDedge.
He pointed out that second-generation Bruton’s tyrosine kinase (BTK) inhibitors such as acalabrutinib (Calquence) may pose a lower risk of atrial fibrillation than the BTK inhibitor ibrutinib used in the CLL2-GIVe study.
In general, however, the rationale for the combination is sound, Dr. Danilov said.
“Of all the patient populations that we deal with within CLL, this probably would be most appropriate for this type of therapy. Patients with deletion 17p or TP53 mutations still represent an unmet medical need compared to other patients who don’t have those mutations,” he said.
Patients with CLL bearing the mutations have lower clinical response rates to novel therapies and generally do not respond well to chemoimmunotherapy, he said.
“The question becomes whether using these all at the same time, versus sequential strategies – using one drug and then after that, at relapse, another – is better, and obviously this trial doesn’t address that,” he said.
The investigators enrolled 24 men and 17 women with untreated CLL with del(17p) and/or TP53 mutations and adequate organ function (creatinine clearance rate of more than 50 mL/min). The median age was 62 (range 35-85 years); 78% of patients had Binet stage B or C disease. The median Cumulative Illness Rating Scale (CIRS) score was 3 (range 0 to 8).
All patients received treatment with the combination for 6 months. The CD20 inhibitor obinutuzumab was given in a dose of 1,000 mg on days 1, 8 and 15 of cycle 1 and day 1 of cycles 2-6. The BTK inhibitor ibrutinib was given continuously at a dose of 420 mg per day beginning on the first day of the first cycle. Venetoclax, a B-cell lymphoma 2 (BCL-2) inhibitor, was started on day 22 of cycle 1, and was increased to 400 mg per day over 5 weeks until the end of cycle 12.
If patients achieved a complete remission (CR) or CR with incomplete recovery of blood counts (CRi) according to International Workshop on CLL criteria at final restaging (performed with imaging at the end of cycle 12 followed by bone marrow biopsy 2 months later), ibrutinib would be stopped beginning at cycle 15. Patients who did not have a CR or CRi would continue on ibrutinib until cycle 36.