From the Journals

Targeted triplet shows potential for B-cell cancers



A triplet combination of targeted agents ublituximab, umbralisib, and ibrutinib may be a safe and effective regimen for patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) and other B-cell malignancies, according to early study results.

The phase 1 trial had an overall response rate of 84% and a favorable safety profile, reported lead author Loretta J. Nastoupil, MD, of the University of Texas MD Anderson Cancer Center, Houston, and her colleagues. The results suggest that the regimen could eventually serve as a nonchemotherapeutic option for patients with B-cell malignancies.

“Therapeutic targeting of the B-cell receptor signaling pathway has revolutionized the management of B-cell lymphomas,” the investigators wrote in the Lancet Haematology. “Optimum combinations that result in longer periods of remission, possibly allowing for discontinuation of therapy, are needed.”

The present triplet combination included ublituximab, an anti-CD20 monoclonal antibody; ibrutinib, a Bruton tyrosine kinase inhibitor; and umbralisib, a phosphoinositide 3-kinase delta inhibitor.

A total of 46 patients with CLL/SLL or relapsed/refractory B-cell non-Hodgkin lymphoma received at least one dose of the combination in dose-escalation or dose-expansion study sections.

In the dose-escalation group (n = 24), ublituximab was given intravenously at 900 mg, ibrutinib was given orally at 420 mg for CLL and 560 mg for B-cell non-Hodgkin lymphoma, and umbralisib was given orally at three dose levels: 400 mg, 600 mg, and 800 mg.

In the dose-expansion group (n = 22), umbralisib was set at 800 mg while the other agents remained at the previous doses; treatment continued until intolerance or disease progression occurred. The investigators monitored efficacy and safety at defined intervals.

Results showed that 37 out of 44 evaluable patients (84%) had partial or complete responses to therapy.

Among the 22 CLL/SLL patients, there was a 100% overall response rate for both previously treated and untreated patients. Similarly, all three of the patients with marginal zone lymphoma responded, all six of the patients with mantle cell lymphoma responded, and five of seven patients with follicular lymphoma responded. However, only one of the six patients with diffuse large B-cell lymphoma had even a partial response.

The most common adverse events of any kind were diarrhea (59%), fatigue (50%), infusion-related reaction (43%), dizziness (37%), nausea (37%), and cough (35%). The most common grade 3 or higher adverse events were neutropenia (22%) and cellulitis (13%).

Serious adverse events were reported in 24% of patients; pneumonia, rash, sepsis, atrial fibrillation, and syncope occurred in two patients each; abdominal pain, pneumonitis, cellulitis, headache, skin infection, pleural effusion, upper gastrointestinal bleeding, pericardial effusion, weakness, and diarrhea occurred in one patient each. No adverse event–related deaths were reported.

“The findings of this study establish the tolerable safety profile of the ublituximab, umbralisib, and ibrutinib triplet regimen in chronic lymphocytic leukemia or small lymphocytic lymphoma and relapsed or refractory B-cell non-Hodgkin lymphoma,” the investigators wrote. “This triplet combination is expected to be investigated further in future clinical trials in different patient populations.”

The study was funded by TG Therapeutics. The authors reported financial relationships with TG Therapeutics and other companies.

SOURCE: Nastoupil LJ et al. Lancet Haematol. 2019 Feb;6(2):e100-9.

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