Isatuximab is unlikely to yield a response among patients with refractory T cell-acute lymphoblastic leukemia (T-ALL) or T cell-lymphoblastic lymphoma (T-LBL), according to research published in Cancer Medicine.
T-ALL and T-LBL, diseases of bone marrow progenitor cells, are linked with a high rate of relapse. Among patients older than 50 years, previously published work suggests the 5-year overall survival rate is approximately 25%, indicating an area of serious unmet clinical need.
It has also previously been established that both T-ALL and T-LBL show abnormally high CD38 expression, and such expression is linked with both disease proliferation and tumor growth. For this single-arm phase 2 study (ClinicalTrials.gov Identifier: NCT02999633), researchers evaluated whether isatuximab, an anti-CD38 monoclonal antibody, is safe and effective among patients with T-ALL or T-LBL.
Overall, 14 patients were included and received isatuximab 20 mg/kg. The median patient age was 33 years (range, 16-74), 85.7% of patients were male sex, 78.6% of patients had T-ALL, and 21.4% of patients had T-LBL. At baseline, 50% of patients had relapsed disease, 35.7% of patients had refractory disease, and 14.3% of patients had relapsed and refractory disease; the average number of prior therapy lines was 5.5.
At the time of analysis, no complete responses or complete responses with incomplete hematologic recovery were noted, and 11 patients had progressive disease. A total of 3 patients died of aplasia before response evaluation.
There were 10 patients (71.4%) who had a treatment-related adverse event (AE), of which the most common was an infusion reaction. Grade 3 or worse AEs occurred in 21.4% of patients.
“Most patients in the study discontinued treatment before optimal blood levels of isatuximab could be reached,” the authors wrote. “The poor response and safety profile of isatuximab monotherapy in this study led to an unsatisfactory risk/benefit ratio for this cohort of patients.”
Disclosure: The study author(s) declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of authors’ disclosures.
Boissel N, Chevallier P, Doronin V, et al. Isatuximab monotherapy in patients with refractory T-acute lymphoblastic leukemia or T-lymphoblastic lymphoma: Phase 2 study. Cancer Med. Published online February 2, 2022. doi:10.1002/cam4.4478