A pilot study of lower doses of ibrutinib in patients with chronic lymphocytic leukemia.

Abstract

Ibrutinib is highly efficacious and used at 420 mg/d for treatment of chronic lymphocytic leukemia (CLL). We previously demonstrated a decline in Bruton's tyrosine kinase (BTK) protein levels in CLL cells after 1 cycle of ibrutinib, suggesting ibrutinib dose could be lowered after the first cycle without loss of biological effect. To test this postulate, a pilot study (NCT02801578) was designed to systematically reduce ibrutinib dosing within the same patient with CLL over the course of three 28-day cycles. After an initial cycle of 420 mg/d, the dose was reduced to 280 mg/d in cycle 2, and then to 140 mg/d in cycle 3. Eleven patients began study treatment, and 9 completed the 3 cycles. Plasma and intracellular pharmacokinetics (PK), BTK occupancy, and pharmacodynamic (PD) response at different doses of ibrutinib were compared. Plasma and intracellular levels of ibrutinib were dose-dependent, and even the lowest dose was sufficient to occupy, on average, more than 95% of BTK protein. In concert, BTK downstream signaling inhibition was maintained with 140 mg/d ibrutinib in cycle 3, and there were comparable reductions in total and phospho-BTK (Tyr223) protein levels across 3 cycles. Reductions of plasma chemokine CCL3 and CCL4 levels, considered to be biomarkers of ibrutinib response, were similar during the 3 cycles. These PK/PD data demonstrate that after 1 cycle of ibrutinib at the standard 420 mg/d dose, the dose can be reduced without losing biological activity. Clinical efficacy of lower doses needs to be systematically evaluated. Such dose reductions would lower drug cost, lessen untoward toxicity, and facilitate rationale-based combinations. This trial was registered at www.clinicaltrials.gov as #NCT02801578.

• Authors: Lisa S Chen, Prithviraj Bose, Nichole D Cruz, Yongying Jiang, Qi Wu, Philip A Thompson, Shuju Feng, Michael H Kroll, Wei Qiao, Xuelin Huang, Nitin Jain, William G Wierda, Michael J Keating, Varsha Gandhi
• Journal: Blood (Blood) Vol. 132 Issue 21 Pg. 2249-2259 (11 22 2018) ISSN: 1528-0020 [Electronic] United States
• PMID: 30254130 (Publication Type: Clinical Trial, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2018 by The American Society of Hematology.

Chemical References

• Piperidines
• Protein Kinase Inhibitors
• Pyrazoles
• Pyrimidines
• ibrutinib
• Agammaglobulinaemia Tyrosine Kinase
• Adenine

Topics

• Adenine (analogs & derivatives)
• Agammaglobulinaemia Tyrosine Kinase (antagonists & inhibitors, metabolism)
• Aged
• Dose-Response Relationship, Drug
• Female
• Humans
• Leukemia, Lymphocytic, Chronic, B-Cell (drug therapy, metabolism)
• Male
• Middle Aged
• Pilot Projects
• Piperidines
• Protein Kinase Inhibitors (administration & dosage, therapeutic use)
• Pyrazoles (administration & dosage, therapeutic use)
• Pyrimidines (administration & dosage, therapeutic use)
• Signal Transduction (drug effects)
• Treatment Outcome