Patients with relapsed or refractory chronic lymphocytic leukemia (CLL) or small lymphocytic leukemia (SLL) who show a deletion of the short arm of chromosome 17 (del 17p) typically see a rapid progression of their disease, with an average life expectancy of less than 2 years once the disease relapses or stops responding to treatment.
In the largest prospective trial dedicated to treating patients with this disease profile, ibrutinib showed marked efficacy in overall response rates, according to data presented December 8, 2014, at the 56th Annual Meeting of the American Society of Hematology held in San Francisco.
The study, led by Susan O’Brien, MD, involved 144 patients: 137 with CLL and 7 with SLL. All had del 17p, their median age was 64 years, and 63% were stage III or IV. Patients received 420 mg of oral ibrutinib once daily until progression; all patients receiving at least 1 dose were included in the analysis. The overall rate of response (ORR) was 82.6%, including 17.4% with partial response with lymphocytosis. Complete response with incomplete bone marrow recovery was reported in 3 patients. An Independent Review Committee-assessed ORR is pending.
At a median follow-up of 13 months, the median progression-free survival and duration of response by investigator determination had not been reached. However, at 12 months, 79.3% of the patients were alive and progression-free and 88.3% of the responders were progression-free. Progressive disease was reported in 20 patients.
The most frequent adverse events (AEs) were diarrhea (36%), fatigue (30%), cough (24%), and arthralgia (22%). Atrial fibrillation was reported in 11 patients. Seven patients reported basal or squamous cell skin cancer. One patient had plasma cell myeloma.
The most frequent grade 3-4 AEs were neutropenia (14%), anemia (8%), pneumonia (8%), and hypertension (8%). Major hemorrhage was reported in 7 patients, all grade 2 or 3, and 16 patients stopped therapy due to AEs, with 8 later having fatal events.
At the time of data cut off, median treatment duration was 11.1 months, and 101 of the 144 patients continued treatment with ibrutinib.