Clinical-stage biopharmaceutical company Pharmacyclics has announced results from Phase II study of oral Bruton's tyrosine kinase (BTK) inhibitor, Ibrutinib, conducted in patients with Waldenstrom's Macroglobulinemia (WM).
The Phase II study, which is designed to assess the efficacy and tolerability of ibrutinib, evaluated 35 relapsed/refractory WM patients Memorial Health System, which received a median of two prior therapies.
According to the data, the best overall response rate was 83%, with the decrease in bone marrow disease burden after six treatment cycles was 40% from 70%, while IgM levels reduced from 3,190mg/dL at baseline to 1,232mg/dL.
The red blood cell production also improved with increasing levels of hematocrit from 30.8% to 39.7%.
Patients with WM exhibited similar safety profile as compared to other B-cell malignancies, while infrequent grade 3 and higher adverse events were associated with ibrutinib treatment.
Waldenstrom's Research Bing Center director and Dana-Farber Cancer Institute and Brigham and Women's Hospital, Boston, attending physician Dr Steven Treon said the data provided further evidence of the role of BTK in tumour growth, in addition to activity and tolerance of ibrutinib for Waldenstrom's patients.
"Despite the relatively small patient population, there are currently no approved treatments specifically for Waldenstrom's, so the need for novel therapies such as ibrutinib should not be underestimated," Treon said.
With a minimum of six cycles of follow up, 91.4% of patients remained on the study.
In order to evaluate the safety and efficacy of ibrutinib in WM, an additional 28 patients were included in the study, which currently has enrolled a total of 63 patients.
The investigational ibrutinib is being jointly developed by Pharmacyclics and Janssen Research & Development.