Acalabrutinib, a next-generation Bruton tyrosine kinase inhibitor, provides prolonged progression-free survival and better tolerability, compared with standard-of-care regimens for relapsed or refractory chronic lymphocytic leukemia (CLL), according to final results from the phase 3 ASCEND study.
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The estimated 18-month progression-free survival (PFS) at a median of 22 months was 82% in 155 patients treated with acalabrutinib, compared with 48% in 155 treated with investigator’s choice of either idelalisib-rituximab (IdR) or bendamustine-rituximab (BR), which were given in 119 and 36 patients, respectively, Paolo Ghia, MD, PhD, reported at the Society of Hematologic Oncology virtual meeting.
The benefits of acalabrutinib were apparent regardless of high-risk genetic characteristics: Those with and without both del(17p) and TP53 mutations had similarly good PFS outcomes with acalabrutinib versus IdR/BR (HRs, 0.11 and 0.29, respectively), as did those with versus without unmutated IgVH (HRs, 0.28 and 0.30, respectively), said Dr. Ghia, professor of medical oncology at the Università Vita-Salute San Raffaele and IRCCS Ospedale San Raffaele, Milan.
The median overall survival was not reached in either arm, but estimated 18-month OS was 88% in both groups, likely because of the crossover being allowed for nonresponders in the IdR/BR groups, he noted.
Overall responses
The investigator-assessed overall response rates, including partial response or better, were also similar in the groups at 80% and 84%, respectively, and ORR, including partial response with lymphocytosis, was 92% versus 88%.
The duration of response was not reached in the acalabrutinib arm versus 18 months with IdR/BR, and estimated duration of response was 85% versus 49%.
The median drug exposure with acalabrutinib was approximately double that with IdR and about four times that of BR, Dr. Ghia said, noting that the difference between acalabrutinib and BR is explained by the short 6-month duration of treatment with BR, but the difference between acalabrutinib and IdR is because of adverse events (AEs).
Adverse events
AEs were the most common reason for treatment discontinuation in all three groups, but they led to discontinuation in only 16% with acalabrutinib versus 56% with IdR, he added.
The rates of AEs and AEs of clinical interest were generally similar to those reported at the interim analysis as presented in 2019 at the European Hematology Association annual meeting and published in the Journal of Clinical Oncology, despite the additional 6 months of follow up, he said.
Additionally, the incidence of grade 3 or higher AEs, serious AEs, and treatment-related AEs were all greater with IdR than with acalabrutinib or BR. The most common AEs with acalabrutinib were headache, neutropenia, diarrhea, and upper-respiratory infection, which were mostly grade 1 or 2. The most common grade 3 or higher AEs were neutropenia, anemia, and pneumonia, which were reported in 12%, 17%, and 7% of patients.
Confirmatory results
“The final results from the ASCEND study confirm the findings at the interim analysis and support the favorable efficacy and safety of acalabrutinib versus standard-of-care regimens ... in patients with relapsed/refractory CLL,” Dr. Ghia said.
“Overall, these final results from ASCENT support the use of acalabrutinib in patients with relapsed/refractory CLL, including those with high-risk genetic features.”
This study was sponsored by Acerta Pharma. Dr. Ghia reported consulting or advisory roles, grant or research funding, and/or honoraria from Abbvie, BeiGene, Janssen, Gilead Sciences, Sunesis Pharmaceuticals, Juno Therapeutics, ArQule, Adaptive Biotechnologies, Dynamo Therapeutics, MEI Pharma, and Novartis.
SOURCE: Ghia P et al. SOHO 2020, Abstract CLL-091.