April 17, 2020
Single-agent ibrutinib was found to have both sustained responses and long-term tolerability for the treatment of first-line or relapsed/refractory chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), according to a study published in Clinical Cancer Research.
John C Byrd, MD, division of hematology, department of medicine, The Ohio State University Medical School, and colleagues conducted a phase 1b/2 study with an extended follow-up up to 8 years, representing the longest follow-up for single agent ibrutinib, or any BTK inhibitor, to date.
The phase 1b/2 PCYC-1102 (n=133) and extension study PCYC-1103 (n=199) comprised patients receiving single-agent ibrutinib in first-line or relapsed/refractory CLL/SLL.
Patient’s average overall response rate for both studies was 89% with similar rates in first-line (87%; complete response, 35%) and relapsed/refractory settings (89%; 10%).
Progression-free survival (PFS) rates for an estimated 7 years were 83% in first-line and 34% in relapsed/refractory settings. The researcher noted that 4 patients had CLL progression (n=11 with Richter's transformation).
“Median PFS was not reached with first-line ibrutinib,” Dr Byrd and colleagues explained. “In relapsed/refractory CLL/SLL, median PFS was 52 months overall, 26 months in patients with chromosome 17p deletion, 51 months with 11q deletion, not reached with trisomy 12 or 13q deletion, and 88 months in patients without these cytogenetic abnormalities.”
The estimated 7-year overall survival rates were 84% and 55% for first-line and relapsed/refractor, respectively.
Most commonly observed grade ≥3 adverse events were hypertension (28%), pneumonia (24%), and neutropenia (18%). “Adverse events leading to discontinuation in ≥2 patients were only observed in the relapsed/refractory setting (sepsis, diarrhea, subdural hematoma, Richter's transformation),” concluded the researchers.
Byrd JC, Furman RR, Coutre SE, et al. Ibrutinib Treatment for First-Line and Relapsed/Refractory Chronic Lymphocytic Leukemia: Final Analysis of the Pivotal Phase 1b/2 PCYC-1102 Study [published online ahead of print, 2020 Mar 24]. Clin Cancer Res. 2020;clincanres.2856.2019. doi:10.1158/1078-0432.CCR-19-2856