The US Food and Drug Administration has approved ibrutinib (Imbruvica Capsules, Pharmacyclics, Inc.) for the treatment of patients with Waldenstrom’s macroglobulinemia (WM). 

Ibrutinib was initially approved in November 2013 for the treatment of patients with mantle cell lymphoma (MCL) who have received at least one prior therapy.  

Ibrutinib also received approval in February 2014 for the treatment of chronic lymphocytic leukaemia (CLL) in patients who received at least one prior therapy and in July 2014 for the treatment of CLL with 17p deletion.

The approval was based on demonstration of durable responses in a single arm, multi-centre clinical trial enrolling 63 patients with previously treated WM. 

Patients received ibrutinib 420 mg orally once daily.

The response rate included complete response (CR), very good partial response (VGPR), and partial response (PR).

The response rate was 61.9% (95%CI 48.8, 73.9).

The responses consisted of VGPR (11.1%) and PR (50.8%). 

No patient achieved a complete response.

The median response duration was not reached (range of 2.8 to 18.8 months). 

The median time to response was 1.2 months.

The most common adverse reactions (greater than or equal to 25%) in patients with B-cell malignancies (MCL, CLL, WM) were thrombocytopenia, neutropenia, diarrhoea, anaemia, fatigue, musculoskeletal pain, bruising, nausea, upper respiratory tract infection, and rash.

The recommended dose and schedule for ibrutinib for the treatment of patients with WM is 420 mg orally once daily.

Click here for full prescribing information, including clinical trial information, safety, dosing, drug-drug interactions and contraindications.

Source: FDA