People with progressive forms of multiple sclerosis (MS) and past exposure to the Epstein-Barr virus are responding to a potential immunotherapy known as ATA188, tolerating the treatment well and with signs that suggest effectiveness, early updated data from an ongoing Phase 1 trial show.
The research, “Preliminary safety and efficacy of ATA188, a pre-manufactured, unrelated donor (off-the-shelf, allogeneic) Epstein-Barr virus-targeted T-cell immunotherapy for patients with progressive forms of multiple sclerosis,” was presented at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) held in Stockholm (Sept. 11–13).
Infection with the Epstein-Barr virus (EBV) is linked to a greater susceptibility to MS. EBV promotes the expansion of immune B-cells, which can produce autoantibodies against myelin, the protective coating of nerve fibers that is progressively damaged in this disease.
People with MS are believed to be deficient in T-cells, which would normally kill EBV-infected B-cells.
ATA188, by Atara Biotherapeutics, is designed to overcome this deficiency by providing allogeneic immune T-cells that target EBV in B-cells. (Allogeneic cells are from donors with no family or genetic relationship to the recipient; an advantage is that these cells are available immediately, or “off-the-shelf.”)
The Phase 1 study (NCT03283826), taking place in the U.S. and Australia, is assessing the safety and efficacy of ATA188 in progressive MS patents — here, a near equal mix of secondary progressive disease (SPMS) and primary progressive MS (PPMS) — ages 18 to 66. Patients are assigned to four groups, each testing a different cell dose: 5 x 106, 1 x 107, 2 x 107, and 4 x 107.
Clinically recognized MS scales are assessing ATA188 effectiveness at baseline (study start), and at roughly 3, 6, and 12 months after initial treatment. These include the Expanded Disability Status Scale (EDSS), the Fatigue Severity Score, the MS Impact Scale, the Timed 25-Foot Walk (T25FW) — where patients walk 25 feet as quickly and safely as possible — the 9-Hole Peg Test of hand and finger skills, 12-Item MS Walking Scale, and tests of visual acuity.
Early data previously reported showed that treatment with ATA188 was well-tolerated across the four groups, with no evidence of cytokine release syndrome (a form of systemic inflammatory response), graft versus host disease (which refers to the attack of the host’s cells by transplanted stem cells), or dose-limiting toxicities.