EMBOLD data covering over 90 MS patients now due in November

Progressive MS patients were treated with ATA188 in Phase 1/2 study

Margarida Maia, PhD avatar

by Margarida Maia, PhD |

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Atara Biotherapeutics now is planning to announce in November the one-year data from its EMBOLD Phase 1/2 study, which is testing the company’s experimental treatment ATA188 for progressive forms of multiple sclerosis (MS).

The results, originally expected in October, will cover the trial’s primary endpoint of confirmed easing of disease-related disability — defined as an improvement in two study visits in a row — as based on the Expanded Disability Status Scale (EDSS), as well as other secondary clinical endpoints.

The data will be based on EDSS scores and the findings of other measures obtained from more than 90 patients who have completed at least one year of follow-up in the study.

“We are excited to soon conduct the primary analysis of the EMBOLD Phase 2 study in progressive MS, with clinical and biomarker data from more than 90 patients,” Pascal Touchon, president and CEO of Atara, said in a company press release.

The release stated that “Atara plans to communicate data from the primary analysis of the double-blind placebo-controlled … study in progressive MS in early November.”

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#ECTRIMS2022 – ATA188 Could Be ‘Game Changing’ for Progressive MS

Treatment designed to fight cells infected by Epstein-Barr virus

In MS, the immune system launches an attack against the body’s own tissues, causing inflammation and damage to nerve cells in the brain and spinal cord. Exactly what triggers this is unknown, but infection with the Epstein-Barr virus (EBV) is now established as a leading environmental risk factor for developing MS later in life.

EBV is a common virus best known for causing infectious mononucleosis, often simply called mono. After the initial infection, the virus can stay dormant inside B-cells, the immune cells responsible for producing antibodies.

ATA188 is an experimental therapy that uses immune T-cells to fight of EBV-infected immune cells in MS patients. It contains T-cells obtained from healthy donors who have previously been infected with EBV; the cells are, therefore, primed to recognize certain EBV proteins and launch an attack against the infected cells.

Atara has been testing the therapy candidate in people with progressive MS in the two-part EMBOLD trial (NCT03283826) since its launch in 2017. The trial specifically is examining how safe and well tolerated ATA188 is, and how well it improves clinical disability in people with nonactive primary progressive or nonactive secondary progressive MS.

The study was a double-blinded one, meaning that neither participants nor researchers knew which patients were receiving ATA188 and which were given the placebo.

Data from the trial’s Phase 1 part and its four-year extension portion showed that ATA188 may help patients achieve confirmed disability improvement, or a lessening of disability, defined as a reduction in EDSS scores recorded in at least two consecutive study visits.

Of the trial’s initial 24 patients, seven had disability improvements and 13 had maintained stable disability scores over about three years of follow-up. This benefit was maintained over time, with patients who experienced improvements continuing to have them at least after a median of 27.5 months, or more than two years.

In the Phase 2 part, patients were randomly assigned to receive ATA188 or a placebo, given in two treatment cycles, for one year. Then, in the second year, patients in the placebo group also received two cycles of ATA188, while the other group were given one cycle of ATA188 and one cycle of a placebo.

After completing the two-year trial, patients may enter an open-label extension and receive ATA188 for up to three more years.

So far, data have come from an initial group of 34 patients observed for at least six months and 15 patients who were followed for at least one year. However, that early data did not provide enough evidence to make definite conclusions about the benefits of ATA188.

In addition to announcing results from the primary outcome measure of confirmed disability improvement, the company anticipates sharing data for patients who have been observed for longer than one year.

Atara also has plans to present a new biomarker analysis from EMBOLD’s ongoing Phase 1 portion at the International Society of Neuroimmunology (ISNI) congress, being held August 20-24 in Canada.

According to this analysis, patients who experienced confirmed disability improvement with ATA188 had lower accumulation of glial fibrillary acidic protein (GFAP) in blood, a potential biomarker of disease progression in MS.