---
schema_version: "secwatch.filing_event.v1"
accession: "0001140361-25-045836"
form_type: "8-K"
ticker: "INSM"
cik: "0001104506"
company_name: "INSMED Inc"
filed_at: "2025-12-17T23:59:59+00:00"
generated_at: "2026-05-16T12:51:55.959730+00:00"
event_type: "other_material"
sentiment: "negative"
materiality_score: 0.8
calibrated_materiality_score: 0.8
confidence: "high"
source: SEC EDGAR
---

# Insmed brensocatib fails Phase 2b CRSsNP; acquires INS1148 antibody

## Summary
- Phase 2b BiRCh study missed primary endpoint: placebo LS mean -2.44, brensocatib 10mg -2.21, 40mg -2.33.
- All secondary endpoints also not met; Insmed discontinues CRSsNP program immediately.
- Brensocatib well tolerated with no new safety signals; 40 mg dose had 69.9% TEAEs vs 65.3% placebo.
- Acquired INS1148 (anti-SCF248 mAb) from Opsidio; plans Phase 2 in interstitial lung disease and asthma.
- INS1148 targets only inflammatory c-Kit signaling, sparing homeostatic pathways, potentially first-in-class.

## SEC filing metadata
- accession: 0001140361-25-045836
- form_type: 8-K
- ticker: INSM
- cik: 0001104506
- company_name: INSMED Inc
- filed_at: 2025-12-17T23:59:59+00:00
- event_type: other_material
- sentiment: negative
- materiality_score: 0.8
- calibrated_materiality_score: 0.8
- confidence: high
- sec_items: 7.01, 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1104506/000114036125045836/0001140361-25-045836-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1104506/000114036125045836/ef20061465_8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001140361-25-045836
- JSON: https://secwatch.observer/filing/0001140361-25-045836.json
- Plain text: https://secwatch.observer/filing/0001140361-25-045836.txt

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