Ibrutinib Effective As First-line Therapy for Waldenstrom Macroglobulinemia

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Ibrutinib is used among patients with WM who have previously received treatment, but its efficacy as a first-line therapy among treatment-naive patients is unknown.
Ibrutinib is used among patients with WM who have previously received treatment, but its efficacy as a first-line therapy among treatment-naive patients is unknown.
The following article features coverage from the American Society of Hematology (ASH) 2017 meeting. Click here to read more of Cancer Therapy Advisor's conference coverage.

Ibrutinib is a safe and highly active treatment among previously untreated patients with Waldenstrom macroglobulinemia (WM), according to a poster being presented at the 2017 American Society of Hematology (ASH) Annual Meeting in Atlanta, Georgia.1

Ibrutinib — a Bruton's tyrosine kinase (BTK) inhibitor — is currently used among patients with WM who have previously received treatment, but its efficacy as a first-line therapy among treatment-naive patients is unknown.

For this prospective phase 2 study (ClinicalTrials.gov Identifier: NCT02604511), researchers enrolled 30 patients with untreated WM and administered ibrutinib 420 mg daily. Patients' baseline characteristics included median serum IgM of 4369 and median bone marrow disease involvement 65%. All patients had MYD88 mutation–positive disease, and 47% of patients had a CXCR4 mutation.

The median time on therapy was 8.1 months; the median time on therapy for patients with a CXCR4 wild-type or CXCR4 mutation was 9.4 months vs 8.0 months, respectively (P = .98). The overall response rate was 96.7%, the major response rate (greater than partial response) was 80%, and a very good partial response was reached by 17% of patients. No patients had a complete response.

Median serum IgM levels decreased from 4380 to 1786 (P = .0001) at best response; at baseline, 60% of patients had a serum IgM greater than 3000 mg/dL compared with just 7% of patients at best response (P < .0001).

At best response, median bone marrow involvement was reduced to 20% from 65% (P < .0001), and 70% and 80% of patients with adenopathy and splenomegaly, respectively, had a reduction or resolution of these conditions. Patients also had an increase in median hemoglobin levels, from 10.3 to 13.6 g/dL (P < .0001).

Mutated CXCR4 was associated with delayed patient response to ibrutinib.

The authors concluded that “[o]ur findings provide the first report of activity and safety of ibrutinib in previously untreated and symptomatic patients with [WM], and show that ibrutinib is highly active and well-tolerated as a single agent, with no unexpected toxicities.”

Read more of Cancer Therapy Advisor's coverage of the American Society of Hematology (ASH) 2017 meeting by visiting the conference page.

Reference

  1. Treon SP, Gustine J, Meid K, et al. Ibrutinib is highly active as first line therapy in symptomatic Waldenstrom's macroglobulinemia. Oral presentation at: American Society of Hematology 59th Annual Meeting & Exposition; December 9-12, 2017; Atlanta, GA.

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