Photo from Janssen Biotech
Health Canada has approved the BTK inhibitor ibrutinib (Imbruvica) as a treatment for patients with Waldenström’s macroglobulinemia (WM).
Ibrutinib was first approved in Canada in November 2014 for the treatment of patients with chronic lymphocytic leukemia (CLL), including those with 17p deletion, who have received at least one prior therapy, or for the frontline treatment of patients with CLL and 17p deletion.
In July 2015, ibrutinib was granted conditional approval for the treatment of patients with relapsed or refractory mantle cell lymphoma.
Health Canada’s approval of ibrutinib for WM was based on results of a multicenter, phase 2 study in which researchers tested the drug (given at 420 mg once daily) in 63 patients with previously treated WM.
The patients’ median age was 63 (range, 44-86), and their median number of prior therapies was 2 (range, 1-11).
Initial data showed an overall response rate of 87.3% in patients who received ibrutinib for a median of 11.7 months.
Updated results from the study were published in NEJM in April 2015. After a median treatment duration of 19.1 months, the overall response rate was 91%.
At 24 months, the estimated rate of progression-free survival was 69%, and the estimated rate of overall survival was 95%.
The most common grade 2-4 adverse events were neutropenia (22%) and thrombocytopenia (14%). Ibrutinib-related neutropenia and thrombocytopenia were reversible but required a dose reduction in 3 patients and treatment discontinuation in 4 patients.
Grade 2 or higher bleeding events occurred in 4 patients, and there were 15 infections considered possibly related to ibrutinib.
Treatment-related atrial fibrillation (AFib) occurred in 3 patients, all of whom had a prior history of paroxysmal AFib. AFib resolved when treatment was withheld, and all 3 patients were able to continue on therapy per protocol without an additional event.
Ibrutinib is co-developed by Cilag GmbH International (a member of the Janssen Pharmaceutical Companies) and Pharmacyclics LLC, an AbbVie company. Janssen Inc. markets ibrutinib as Imbruvica in Canada.
