---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-205107"
form_type: "8-K"
ticker: "APVO"
cik: "0001671584"
company_name: "Aptevo Therapeutics Inc."
filed_at: "2025-09-16T23:59:59+00:00"
generated_at: "2026-05-17T06:30:24.062070+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Aptevo reports 100% remission rate in Cohort 3 of Phase 1b/2 RAINIER trial for mipletamig in AML

## Summary
- 100% remission rate (CR/CRi) in Cohort 3 with mipletamig + venetoclax + azacitidine for newly diagnosed AML unfit for intensive chemo.
- No dose-limiting toxicities or cytokine release syndrome observed across all RAINIER cohorts; safety profile clean.
- 40% of treated patients achieved minimal residual disease (MRD)-negative status, a marker associated with improved outcomes.
- Cohort 4 now enrolling at next dose level; data expected at major medical conference in Q4 2025.
- Frontline AML market is multibillion-dollar; mipletamig could redefine standard of care if later-stage data confirm.

## SEC filing metadata
- accession: 0001193125-25-205107
- form_type: 8-K
- ticker: APVO
- cik: 0001671584
- company_name: Aptevo Therapeutics Inc.
- filed_at: 2025-09-16T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1671584/000119312525205107/0001193125-25-205107-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1671584/000119312525205107/apvo-20250916.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-205107
- JSON: https://secwatch.observer/filing/0001193125-25-205107.json
- Plain text: https://secwatch.observer/filing/0001193125-25-205107.txt

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