---
schema_version: "secwatch.filing_event.v1"
accession: "0000950170-23-051917"
form_type: "8-K"
ticker: "STRO"
cik: "0001382101"
company_name: "SUTRO BIOPHARMA, INC."
filed_at: "2023-10-04T23:59:59+00:00"
generated_at: "2026-06-10T04:37:59.334202+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.6
calibrated_materiality_score: 0.6
confidence: "high"
source: SEC EDGAR
---

# Sutro Biopharma and Vaxcyte finalize agreement triggering $5M payment; license amended

## Summary
- Vaxcyte agrees to pay Sutro $5.0M upon mutual agreement on Form Definitive Agreement, reached Sept 28, 2023.
- Amendment No. 3 modifies royalty reduction provisions, IP ownership, prosecution, and financial reporting terms.
- Vaxcyte gains rights to independently source cell-free extract from CMOs and option to internally manufacture extract.
- Amendment effective immediately; negotiated under December 2022 letter agreement between the companies.

## SEC filing metadata
- accession: 0000950170-23-051917
- form_type: 8-K
- ticker: STRO
- cik: 0001382101
- company_name: SUTRO BIOPHARMA, INC.
- filed_at: 2023-10-04T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.6
- calibrated_materiality_score: 0.6
- confidence: high
- sec_items: 1.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1382101/000095017023051917/0000950170-23-051917-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1382101/000095017023051917/stro-20230928.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0000950170-23-051917
- JSON: https://secwatch.observer/filing/0000950170-23-051917.json
- Plain text: https://secwatch.observer/filing/0000950170-23-051917.txt

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