NEW YORK – The Food and Drug Administration’s 2016 approval of the Bruton’s tyrosine kinase inhibitor ibrutinib (IB) as a frontline therapy for chronic lymphocytic leukemia (CLL) dramatically improved overall survival rates for patients with this condition. Follow-up data from 8 years after the RESONATE-2 trial indicated that patients with CLL (65 years or older) who remain on IB therapy can expect to live as long as someone in the general population.
Physicians now face two challenges in frontline CLL treatment: finding safe and effective drugs with fewer side effects, allowing patients to maintain therapy; and offering young or genomically high-risk patients treatments that reduce the risk of relapse.
courtesy Dr. Allan
Dr. John N. Allan
said John N. Allan, associate professor at Weill Cornell Medicine, New York, in his presentation on frontline CLL treatments at the Great Debates and Updates Hematologic Malignancies Conference. “This is true even of older patients or those with comorbidities because this class of drug allows us to keep patients on treatment with excellent long-term outcomes.”
Results from the Alpine trial (NCT03734016), which included patients with and without high genomic risk, confirmed the superiority of the second generation Bruton’s tyrosine kinase inhibitor zanubrutinib (ZB) versus ibrutinib in terms of overall response rate 86.2% versus 75.5%, progression free survival 2-years after treatment 79.5% versus 67.3%, and adverse events (AEs) leading to discontinuation 15.4% versus 22.2% respectively.
The SEQUOIA trial (NCT03336333) demonstrated the effectiveness of ZB versus bendamustine + rituximab combination (BR) therapy in treatment-naive CLL / small lymphocytic leukemia patients with normal and high genomic risk. Overall 24-month progression free survival (PFS) was 85% in the ZB cohort vs. 69% in the BR cohort. This trend held true among high-risk subgroups like patients with an unmutated IgVH gene or 11q22.3 gene deletion.
Therapies known as “doublets” and “triplets” (which include a Bruton’s tyrosine kinase inhibitor in addition to other drugs) are not FDA approved for frontline CLL treatment. Yet studies suggest that young patients who are better able to tolerate AEs or high-risk patients with a greater risk of relapse (even on monotherapy maintenance), may derive benefits from multidrug frontline treatment.
“With doublets and triplets, doctors add treatment intensity up front so that patients can have a fixed duration of therapy versus continuous indefinite therapy,” said Vu Nguyen MD, a hematologist at Oakland (Calif.) Medical Center. “This is encouraging because if you can have a fixed duration of treatment, patients can come off treatment agents and hopefully have a prolonged remission and normal lifespan without chronic therapy and side effects.”
The CAPTIVATE study confirmed this approach with 3 cycles of IB followed by 12 cycles of IB + venetoclax leading to a 24-month PFS rate of 94% in patients with high risk or relapse. “Furthermore, 95% of study participants patients less than 70 years old completed 12 months of combination treatment without major problems,” said Dr. Allan. He concluded his remarks by noting that “we need longer term data on the use of combination therapy for frontline CLL treatment to confirm if and when it should be used.”
Dr. Allan disclosed relationships with Adaptive Biotechnologies, ADC Therapeutics, AstraZeneca, BeiGene, Epizyme, Genentech, Janssen, Lilly, Pharmacyclics, and TG Therapeutics. Dr. Nguyen reported no disclosures.