---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-23-273808"
form_type: "8-K"
ticker: "ATRA"
cik: "0001604464"
company_name: "Atara Biotherapeutics, Inc."
filed_at: "2023-11-09T23:59:59+00:00"
generated_at: "2026-06-08T06:43:30.572433+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Atara's Phase 2 ATA188 for non-active PMS misses primary endpoint; cash runway extended beyond Q3 2025

## Summary
- EMBOLD misses primary endpoint; treatment arm CDI 6% vs 33% in Phase 1; placebo rate 16% exceeded expected 4-6%.
- No new safety signals observed; favorable safety profile for ATA188 in the study.
- Company plans significant expense reductions on ATA188; focuses on allogeneic CAR-T pipeline; cash runway extended beyond Q3 2025.
- Catalysts: ATA3431 preclinical data at ASH Dec 2023; Phase 1 data for ATA3219 in B-NHL expected H2 2024.
- Tab-cel partnership with Pierre Fabre provides additional payments and significant double-digit royalties.

## SEC filing metadata
- accession: 0001193125-23-273808
- form_type: 8-K
- ticker: ATRA
- cik: 0001604464
- company_name: Atara Biotherapeutics, Inc.
- filed_at: 2023-11-09T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.85
- calibrated_materiality_score: 0.85
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1604464/000119312523273808/0001193125-23-273808-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1604464/000119312523273808/d139069d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-23-273808
- JSON: https://secwatch.observer/filing/0001193125-23-273808.json
- Plain text: https://secwatch.observer/filing/0001193125-23-273808.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.