Moxetumomab pasudotox shows promise in relapsed, refractory hairy cell leukemia
CHICAGO — The investigational anti-CD22 recombinant immunotoxin, moxetumomab pasudotox, showed a high rate of response and eradicated minimal residual disease among heavily pretreated patients with relapsed/refractory hairy cell leukemia, according to findings from a phase 3 trial presented at the ASCO Annual Meeting.
“Moxetumomab pasudotox had an acceptable tolerability profile and is a nonchemotherapeutic agent that has the potential to become a standard of care for patients with relapsed/refractory hairy cell leukemia,” Robert J. Kreitman, MD, senior investigator at laboratory of molecular biology and head of the clinical immunotherapy section at the NCI, said during his presentation.
Hairy cell leukemia is a highly treatable disease. However, many patients require retreatment after relapse, for whom there is an unmet need for new therapies.
In the multicenter, single-arm, international study, researchers evaluated 40 µg/kg IV moxetumomab pasudotox (MedImmune/AstraZeneca) given on days 1, 3 and 5 of 28-day cycles for up to six cycles in 80 patients (median age, 60 years; 79% men) with relapsed/refractory hairy cell leukemia from 34 centers in 14 countries.
Forty-nine percent of patients had three or more prior lines of therapy and 75% had prior rituximab (Rituxan; Genentech, Biogen).
Durable complete response — defined as complete response with hematologic remission — served as the primary outcome. Secondary outcomes included overall response rate, PFS, safety, immunogenicity and pharmacokinetics.
At a median follow-up of 16.7 months, researchers observed an ORR of 75%, hematologic remission rate of 80%, complete response rate of 41% and durable complete response rate of 30%.
Among 33 patients who achieved a complete response, 82% had immunohistochemistry minimal residual disease-negative status. Eighty-percent of patients achieved hematologic remission, with a median onset of 1.1 months.
Median response duration and median PFS were not reached, Kreitman noted.
The most frequent treatment-related adverse events included nausea (28%), peripheral edema (26%), headache (21%), and pyrexia (20%). Adverse events that led to treatment discontinuation included hemolytic uremic syndrome in 5%, capillary leak syndrome in 3% and increased blood creatinine in 3%.
No treatment-associated deaths occurred. – by Jennifer Southall
Kreitman RJ, et al. Abstract 7004. Presented at: ASCO Annual Meeting; June 1-5, 2018; Chicago.
Disclosures: Kreitman reports receiving patents, royalties or other intellectual property from the NIH/NCI. Please see the abstract for all other authors’ relevant financial disclosures.