13 July 2022 - - US-based T-cell immunotherapy company Atara Biotherapeutics, Inc. (NASDAQ: ATRA) has completed the planned Interim Analysis of the ATA188 Phase 2 randomized, placebo-controlled study (EMBOLD) in June 2022, the company said.

The IA included review by the Independent Data and Safety Monitoring Committee (IDSMC) of the efficacy, safety, and biomarker data available at the data cut off, based on which the IDSMC recommended the study continue without sample size adjustment.

The IA's primary focus was on expanded disability status scale improvement at six months and overall safety, and also included evaluation of EDSS beyond six months for patients with longer treatment duration, as well as other available clinical data and magnetization transfer ratio biomarker data.

The IA was also designed to assess if a sample size increase was needed based on a conditional power modeling approach. The IA was planned to occur before enrolling patient 80 to enable an increased sample size if needed.

The main assessment at the EMBOLD IA was EDSS improvement at six months, which in the 24-patient open label Phase 1 study, appeared to be predictive of confirmed EDSS improvement at 12 months (the primary endpoint for the EMBOLD study).

At the time of the EMBOLD IA, there were EDSS data on 34 patients evaluable at six months and 15 patients at 12 months (across both placebo and active groups with 1: 1 randomization).

Based on the analysis of the EMBOLD data available at the time of the IA, there was not a sufficient dataset to draw conclusions about the predictive value of six months EDSS improvement for 12 months EDSS improvement.

The IDSMC believes the six-month interim endpoint may be an inaccurate measure of the potential of this intervention in this condition.

The IDSMC recommended continuing the study without sample size adjustment until the final analysis of the primary endpoint of confirmed EDSS improvement at 12 months.

After completing the IA in June, the target enrollment of 80 patients was achieved.

Total enrollment will be higher as patients that were already in screening through the end of June will be allowed to continue the enrollment process.

Final read out of the study primary endpoint of confirmed EDSS improvement at 12 months is planned to occur in October 2023.

Atara Biotherapeutics, Inc is a pioneer in T-cell immunotherapy leveraging its novel allogeneic EBV T-cell platform to develop transformative therapies for patients with serious diseases including solid tumors, hematologic cancers and autoimmune disease.

With its lead program in Phase 3 clinical development and currently under review to support registration in Europe, Atara is the most advanced allogeneic T-cell immunotherapy company and intends to rapidly deliver off-the-shelf treatments to patients with high unmet medical need.

Its platform leverages the unique biology of EBV T cells and has the capability to treat a wide range of EBV-associated diseases, or other serious diseases through incorporation of engineered CARs (chimeric antigen receptors) or TCRs (T-cell receptors).

Atara is applying this one platform, which does not require TCR or HLA gene editing, to create a robust pipeline including: tab-cel (tabelecleucel) in Phase 3 development for Epstein-Barr virus-driven post-transplant lymphoproliferative disease (EBV+ PTLD); ATA188, a T-cell immunotherapy targeting EBV antigens as a potential treatment for multiple sclerosis; and multiple next-generation chimeric antigen receptor T-cell (CAR-T) immunotherapies for both solid tumors and hematologic malignancies.

Improving patients' lives is our mission and we will never stop working to bring transformative therapies to those in need.

Atara is headquartered in South San Francisco.