Atara’s Cell Therapies Rise for EBV+ PTLD, Sink for Multiple Sclerosis After Data Updates

Following a positive data announcement, Atara Biotherapeutics is advancing tabelecleucel (tab-cel; Atara Biotherapeutics), its allogeneic Epstein–Barr virus (EBV)-specific T-cell immunotherapy for patients with relapsed or refractory (r/r) or treatment-naïve Epstein-Barr virus-positive post-transplant lymphoproliferative disease (EBV+ PTLD) following solid organ transplant or hematopoietic cell transplant towards biologics license application (BLA) submission as well as an expanded indication.¹

“We are encouraged by our latest pivotal study data for tab-cel supporting our plan to file a BLA in Q2 2024, while our global commercial partner Pierre Fabre is starting to prepare the US launch,” Pascal Touchon, President and Chief Executive Officer, Atara, said in a statement.¹

The BLA for tab-cel will be supported by data from the phase 3 ALLELE study (NCT03394365), which has most recently demonstrated a 49% objective response rate (ORR; P <.0001) in patients with EBV+ PTLD, as well as an acceptable and consistent safety profile.¹ Tab-cel is approved under the name Ebvallo for this indication in Europe.

Atara recently reported data from an expanded population of patients with EBV+ PTLD with central nervous system involvement(CNS EBV+ PTLD) in the phase 2 EBVision trial (NCT04554914), which is also continuing to enroll patients with EBV+ immunodeficiency-associated lymphoproliferative diseases. In18 patients with CNS EBV+ PTLD, including 1patient with no prior treatment who achieved a complete response, ORR was 77.8%. Nonresponders had a 0% 1- and 2-year overall survival (OS) rate and responders had an 85.7% and 66.7% 1- and 2-year OS rate, respectively.Tab-cel was well tolerated, with no reports of serious treatment-related treatment-emergent adverse events (TEAEs) or serious treatment-related neurotoxicity, organ rejection, graft versus host disease, or tumor flare reaction of any grade.¹

WATCH NOW: Amer Beitinjaneh, MD, MSc, MPH, FACP, on Treating EBV+ PTLD With Tab-cel

On the other hand, the company is planning to discontinue the phase 2 EMBOLD trial (NCT03283826) of ATA188, its other allogeneic, EBV T-cell immunotherapy clinical-stage candidate, after it failed its primary endpoint of showing superiority over placebo in patients with multiple sclerosis (MS).²

"We are surprised and deeply disappointed with the results of EMBOLD, particularly for the MS patient community which is in urgent need of new treatment options. We are grateful to the patients and investigators who participated in the study, and to colleagues at Atara for their steadfast work,” Touchon said in a previous statement.² “We are further evaluating the EMBOLD data as we continue to believe in the critical role EBV plays in MS pathogenesis, however we anticipate stopping the study as no treatment benefit was observed.”

EMBOLD did not meet is primary end point of confirmed disability improvement (CDI) by expanded disability status scale (EDSS) at 12 months compared to placebo. Fluid and imaging biomarkers also failed to provide further supportive evidence. Patients in the treatment arm had a 6% CDI compared with a 33% CDI in the phase 1 trial. Investigators also observed a substantially greater than expected placebo rate of 16% for CDI at 12 months compared with an expected rate of 4-6% inpatients with nonactive progressive MS.²

REFERENCES

1. Atara Biotherapeutics to present recent progress and key upcoming milestones at the 42nd annual J. P. Morgan healthcare conference. News release. Atara Biotherapeutics. January 8, 2024. https://investors.atarabio.com/news-events/press-releases/detail/333/atara-biotherapeutics-to-present-positive-new-tab-cel
2.Atara Biotherapeutics announces primary analysis data from phase 2 EMBOLD clinical trial of ATA188 in non-active progressive multiple sclerosis. News release. Atara Biotherapeutics. November 8, 2023. https://investors.atarabio.com/news-events/press-releases/detail/330/atara-biotherapeutics-announces-primary-analysis-data-from