Combining acalabrutinib with obinutuzumab may be safe and effective among patients with treatment-naive or relapsed/refractory chronic lymphocytic leukemia (CLL), according to research published in Cancer Discovery.
Ibrutinib, a Bruton’s tyrosine kinase (BTK) inhibitor, has drastically improved response rates among patients with CLL since its introduction. However, because the drug has alternative targets aside from BTK, there have been high rates of discontinuation due to toxicity in the real world setting, and the drug may not effectively combine with anti-CD20 monoclonal antibodies, which are standard in CLL therapy.
For this phase 1b/2 study, researchers evaluated whether acalabrutinib, a selective BTK inhibitor with fewer alternative targets than ibrutinib, is safe and effective with obinutuzumab, an anti-CD20 antibody, among patients with treatment-naive or relapsed/refractory CLL.
Of 45 included patients, 19 had treatment-naive disease and 26 had relapsed/refractory CLL. Other patient and disease characteristics, including genomic status, were balanced between the groups.
The overall response rate was 95% in the treatment-naive group and 92% in the relapsed/refractory group; the 3-year progression-free survival rates were 94% and 88%, respectively.
Among all patients, the rate of grade 3 to 4 adverse events was 71%. The most common adverse events were decreased neutrophil count (24%), syncope (11%), and decreased platelet count (9%). Five patients discontinued treatment because of treatment toxicity.
Complete response occurred in 32% of treatment-naive patients, compared with 8% of relapsed/refractory patients.
“In this study, acalabrutinib plus obinutuzumab was tolerable, with low rates of discontinuation due to adverse events,” the researchers wrote. “Further study of this combination is warranted in CLL and potentially in other lymphoid malignancies.”
Disclosures: Some authors have declared affiliations with the pharmaceutical industry. Please refer to the original study for a full list of disclosures.
1. Woyach JA, Blachly JS, Rogers KA, et al. Acalabrutinib plus obinutuzumab in treatment-naive and relapsed/refractory chronic lymphocytic leukemia [published online January 8, 2020]. Cancer Discov. doi:10.1158/2159-8290.CD-19-1130