Atara Biotherapeutics has announced initial safety results from the Phase I clinical trial of its allogeneic T-cell immunotherapy ATA188 in patients suffering from progressive multiple sclerosis (MS).

ATA188 is designed to target specific Epstein-Barr virus (EBV) antigens believed to be involved in the pathogenesis of the chronic neurological autoimmune disease.

The primary objective of ATA188’s ongoing multi-centre, open-label, single-arm, dose-escalating Phase I trial is to assess safety and tolerability for progressive MS patients.

According to data, the first three dose cohorts of the T-cell immunotherapy product were found to be well-tolerated without dose-limiting toxicities or ≥3 grade treatment-related, treatment-emergent adverse events.

Atara Biotherapeutics senior vice-president and chief medical officer AJ Joshi said: “We are encouraged by the initial ATA188 safety and tolerability results from the first three cohorts.

“We continue to enrol patients with progressive MS in the fourth and final planned dose escalation cohort and look forward to presenting preliminary efficacy results from the initial cohorts of this study at a scientific congress in the second half of 2019.”

The Phase I trial is currently working towards the determination of a recommended Phase II dose (RP2D).

Atara intends to perform a randomised, double-blind, placebo-controlled Phase Ib extension period for this trial using the RP2D after the open-label, dose-escalation period is complete.

The trial’s key secondary endpoints include clinical improvement measures such as expanded disability status scale (EDSS) and MRI imaging, along with additional clinical activity measures.

A total of 24-30 primary and secondary progressive MS (PPMS, SPMS) patients are expected to be recruited across the US and Australia.