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OST31-164 · OST31

Vaccine (Live attenuated vaccine) · Immune activation, directed at HER2/neu (ERBB2)

Phase 2 Most advanced trial

1 Registered trials

What is OST31-164?

OST31-164 is a live attenuated Listeria monocytogenes vaccine encoding a fusion protein with HER2/neu epitopes and listeriolysin O. It activates T-cell responses against HER2-expressing tumor cells while inhibiting regulatory T cells and myeloid-derived suppressor cells. It is studied in bone cancer.

Summary written with AI from the sources listed at the end of this page.

At a glance

Also known as: OST31
Drug type: Vaccine (Live attenuated vaccine)
Targets: HER2/neu (ERBB2) (antigen)
Mechanism: Immune activation, directed at HER2/neu (ERBB2)
Pathways: MHC I antigen presentation, T-cell activation, Treg inhibition, MDSC inhibition
Therapy area: Oncology
In trials of: OSTX
FDA status: Investigational, not approved in the US. Most advanced trial: Phase 2

🧪 Clinical trials

Trial	Phase	Condition	Status	Sponsor
NCT04974008	Phase 2	Bone Cancer	Active not recruiting	OSTX

Trials of the companies BioRadar tracks, from ClinicalTrials.gov, most advanced phase first.

Conditions studied

Bone Cancer

Other drugs acting on ERBB2

Neratinib FDA approved Trastuzumab Deruxtecan FDA approved Trastuzumab Emtansine FDA approved Zanidatamab FDA approved ADCT-502 Phase 1 BH-30643 Phase 1/2 CGT4255 Phase 1 CUDC-101 Phase 1 ELVN-002 Phase 1 Enozertinib Phase 1/2 NVL-330 Phase 1 TTX-MC138 Phase 1/2

Sources

Updated Oct 3, 2026.

Data: FDA (Drugs@FDA, Purple Book, DailyMed), NIH (NCI Thesaurus, GSRS, RxNorm), ClinicalTrials.gov • Informational purposes only, not medical or investment advice. • All drugs A–Z