NEW YORK –
Dr. Furman
Dr. Richard R. Furman
“In people who are genomically unstable, almost half will have their CLL progress on single agent BTK inhibitor therapy. These patients, I’d like to treat with combination of a Bruton’s tyrosine kinase inhibitor plus venetoclax,” said Richard R. Furman, MD, Morton Coleman MD Distinguished Professor of medicine at Weill Cornell Medicine/New York Presbyterian Hospital. He presented on treating relapsed CLL at the Great Debates and Updates Hematologic Malignancies Conference in New York, April 13-15.
The efficacy of venetoclax (VX) in treating high risk CLL patients was demonstrated in the 2019 CLL14 trial (NCT02242942) in which the main entry criteria were being treatment-naive and being considered “unfit” for treatment, meaning that a patient’s Cumulative Illness Rating Scale score was >6, or they presented with decreased kidney function. Study participants were treated with six cycles of either venetoclax-obinutuzumab (VO) or chlorambucil-obinutuzumab (CO); the 4-year PFS was 74% vs. 35.4% (P < .0001) respectively. After 12 cycles of treatment, the 74% of patients in the VO group achieved undetectable minimal residual disease rate (MRD) vs. 32% in the CO group.
Achievement of MRD did predict for outcome, but Dr. Furman concluded that while MRD is a powerful prognostic tool, it is not clinically useful given the inability of its results to guide therapy. He went on to emphasize that “of those patients who achieved MRD levels of 10-4 after 12 cycles of venetoclax, 50% had worsening and 50% had improvement of the residual disease, suggesting that we do not know the optimal duration of venetoclax treatment, as half of the patients still continue to derive benefit.”
Dr. Furman noted that ibrutinib (IB) and the second-generation drugs zanubrutinib (ZB) and acalabrutinib (AL) are all effective, but that the second-generation Bruton’s tyrosine kinase inhibitors enable patients to derive the benefit of remaining on treatment longer, because the rate of concerning cardiac complications is lower than with IB.
The ALPINE trial (NCT03734016) confirmed ZB’s significantly improved overall response rate at 78.3% vs. IB’s 62.5%, as well as a lower rate of atrial fibrillation (2.5%) vs. IB (10.1%).
Noninferiority of AL vs. IB in high-risk relapsed CLL patients was demonstrated in the ELEVATE-RR trial (NCT02477696) with both drugs having a median PFS of 38.4 months. With a median follow up of 41 months, AL demonstrated less atrial fibrillation/atrial flutter, compared with IB (9.4% vs. 16.0%) with no difference in grade > 3 infections. Furthermore, AL’s half-life being shorter than that of IB means that side effects are shorter lived.
“That’s the advantage of the second generation of Bruton’s tyrosine kinase inhibitors,” said Stefan Glück, MD, PhD, a hematologic oncologist and independent consultant who was formerly affiliated with the Sylvester Comprehensive Cancer Center and taught at the Miller School of Medicine at the University of Miami.
Dr. Glück added that “acalabrutinib and zanubrutinib have demonstrated strong efficacy and safety. When patients no longer respond to these drugs, the addition of VX is crucial. It has a completely different mechanism of action and can reverse resistance to Bruton’s tyrosine kinase inhibitors, allowing them to start working again.”
Dr. Furman also discussed proteolysis-targeting chimeras (PROTACs), one area that he expects to make a significant impact as a future therapy for CLL and many other malignancies. Despite the fact these agents are in phase I studies, he commented that “they appear, thus far, to have tremendous potential.”
Dr. Furman disclosed relationships with Abbvie, Acerta/AstraZeneca, Beigene, Jansen, TG Therapeutics, Genentech-Roche, Incyte Corporation, Loxo Oncology, MEI Pharma, Morphosys, Pharmacyclics, Sanofi/Genzyme, and X4 Pharmaceuticals. Dr. Glück reported no conflicts of interest.