---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-24-272814"
form_type: "8-K"
ticker: "ACLX"
cik: "0001786205"
company_name: "Arcellx, Inc."
filed_at: "2024-12-09T23:59:59+00:00"
generated_at: "2026-05-29T05:44:19.343014+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.85
calibrated_materiality_score: 0.85
confidence: "high"
source: SEC EDGAR
---

# Arcellx iMMagine-1 study: 97% ORR, 62% CR/sCR, no delayed neurotoxicity in RRMM

## Summary
- Phase 2 pivotal iMMagine-1: 86 patients evaluable; ORR 97% (83/86), CR/sCR 62% (53/86) at median 9.5-month follow-up.
- No delayed neurotoxicities (Parkinsonism, cranial nerve palsies, Guillain-Barré) in >150 dosed patients across Phase 1 and iMMagine-1.
- Phase 1 study shows 30.2-month median PFS at 38.1 months follow-up; median OS not reached.
- MRD negativity achieved in 93.1% (54/58) evaluable at ≥10⁻⁵ sensitivity.
- Safety: 86% had Grade ≤1 CRS; 91% had no ICANS; most common Grade ≥3 TEAE was neutropenia (54%).

## SEC filing metadata
- accession: 0001193125-24-272814
- form_type: 8-K
- ticker: ACLX
- cik: 0001786205
- company_name: Arcellx, Inc.
- filed_at: 2024-12-09T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- 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/1786205/000119312524272814/0001193125-24-272814-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1786205/000119312524272814/d917635d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-24-272814
- JSON: https://secwatch.observer/filing/0001193125-24-272814.json
- Plain text: https://secwatch.observer/filing/0001193125-24-272814.txt

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