NEW ORLEANS – The investigative agent ublituximab was well tolerated and demonstrated rapid B-cell depletion in patients with relapsing multiple sclerosis, results from an ongoing phase II trial showed.
“Ublituximab is a novel, chimeric monoclonal antibody targeting a unique epitope on the CD20 antigen, and glycoengineered to enhance affinity for all variants of FcyRIlla receptors, thereby demonstrating greater antibody-dependent cellular toxicity activity than rituximab and ofatumumab,”
In a trial supported by TG Therapeutics, which is developing the agent, Dr. Lovett-Racke of the department of microbial infection and immunity at the Ohio State University Medical Center, Columbus, and her associates reported data from 24 patients who received ublituximab at doses markedly less than those used in ongoing phase III oncology studies, and at a range of infusion times, with a goal of rapid infusions.
The study ran for 48 weeks, and the primary endpoint was responders rate, defined as a percent of patients with at least a 95% reduction in peripheral CD19-positive B-cells within 2 weeks after the second infusion. All patients received the same total dose of 600 mg; only infusion times differed. (Ublituximab was administered on day 1, day 15, and week 24. Placebo IV infusion dose was administered on day 1 and day 15 only.)
The mean age of the study participants was 40 years, and the distribution of time from diagnosis was less than 5 years in 11 patients, 5-10 years in 7 patients, and greater than 10 years in 6 patients.
To date, ublituximab has been well tolerated, with only mild infusion reactions being observed, even with infusion times reduced to 1 hour. The researchers also found that ublituximab resulted in 99% B-cell depletion, meeting the study endpoint of greater than 95% depletion within 2 weeks of the second dose, which is comparable to ocrelizumab.
“Every patient has met the endpoint so far,” Dr. Lovett-Racke said. “Although there is a transient decrease in T cells after the initial dose of ublituximab, T-cell numbers are fairly stable over time. Memory B cells seem slightly more resistant to depletion, but are efficiently depleted in all patients. A comprehensive analysis of B- and T-cell profiles is being performed to understand how B-cell depletion influences T-cell profiles, and to characterize the B-cell repletion.”
TG Therapeutics funded the study. Dr. Lovett-Racke disclosed having received research grants from the National Institutes of Health, the National Multiple Sclerosis Society, and the Strategic Pharmaceutical Academic Research Consortium.