ATLANTA – The phosphoinositide 3-kinase (PI3K) delta inhibitor umbralisib is active and well tolerated as single-agent therapy in patients with relapsed or refractory marginal zone lymphoma, according to findings from the ongoing phase 2 UNITY-NHL study.
The best overall response rate (ORR) among 42 study participants with at least 9 months of follow-up was 52% by both independent review committee (IRC) and investigator assessment, and the complete response rate was 19%,, reported at the annual meeting of the American Association for Cancer Research.
The ORR by IRC assessment for those with extranodal, nodal, and splenic disease was 57%, 42%, and 43%, respectively, and for those with prior chemo-immunotherapy and those refractory to their last line of therapy, the ORR was 53% and 38%, respectively, said Dr. Fowler of MD Anderson Cancer Center, Houston.
The clinical benefit rate was 88%, and the median duration of response and progression-free survival (PFS) have not been reached; 12-month PFS is estimated at 66%, he added.
Patients in the marginal zone lymphoma cohort of the multicohort trial, which is evaluating umbralisib both as monotherapy and as part of various combinations in patients with previously treated non-Hodgkin’s lymphoma, received single agent umbralisib at a dose of 800 mg daily until disease progression or unacceptable toxicity.
“Most patients who have responded continue on drug,” he said in a video interview.
Dr. Fowler also further discussed the findings to date with respect to response, adverse events, and future directions in the wake of the breakthrough therapy designation recently granted by the Food and Drug Administration for umbralisib based on these findings.
“Despite the fact that a lot of things work in the front line, when patients relapse, especially when they become refractory to rituximab, there are limited options available,” he said, noting that currently used treatments are associated with significant adverse event and short remission times. “We still need better options.”