The interim analysis of results from a phase 2 clinical trial of ATA188 for the treatment of multiple sclerosis (MS) has been completed by Atara Biotherapeutics, the developers of the treatment. Based on the interim analysis, the trial will continue without sample size adjustment.

“We are pleased to have completed the target enrollment for the EMBOLD study and look forward to sharing the topline results as planned at an appropriate forum in October 2023,” Jakob Dupont, MD, head of global research and development at Atara, said in a press release.

“We look forward to completing the EMBOLD study as we aspire to demonstrate a potentially transformative profile for ATA188 in patients with progressive MS who have high unmet needs and limited options,” Pascal Touchon, president and chief executive officer of Atara, said.

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The phase 2 trial called EMBOLD is a randomized, placebo-controlled study that aims to evaluate the safety and efficacy of ATA188 as well as its effect on clinical disability, as assessed by confirmed improvements in the Expanded Disability Status Scale (EDSS) at 12 months in patients with primary and secondary progressive MS. 

The interim analysis focused on EDSS improvement at 6 months as well as overall safety. It also assessed whether a sample size increase was necessary. It was concluded that there was not enough data to draw conclusions about the predictive value of EDSS improvement after 6 months and that the trial should continue till the final analysis of confirmed EDSS improvement at 12 months.

The trial is still recruiting participants in the US, Australia, and Canada and is expected to be completed in February 2026.

ATA188 is an off-the-shelf T-cell candidate that can specifically target B cells infected by Epstein-Barr Virus, a virus associated with MS among other conditions.


Atara Biotherapeutics announces completion of the ATA188 phase 2 EMBOLD study interim analysis in patients with progressive MS. News release. Atara Bio; July 12, 2022.

Phase 1/2 study to evaluate the safety and efficacy of ATA188 in subjects with progressive multiple sclerosis (EMBOLD). US National Library of Medicine. Updated June 30, 2022. Accessed July 15, 2022.