aid: third-arc-bio
name: Third Arc Bio
description: >-
  Third Arc Bio is a clinical-stage biotechnology company headquartered in Lower Gwynedd,
  Pennsylvania, developing multifunctional antibodies that build immune synapses to precisely
  activate or inhibit T cells. Its ARCStim platform targets solid tumors and its ARCTag platform
  pursues tissue-specific precision immune regulation for immunology and inflammation (I&I)
  indications; lead program ARC101 is a bispecific T-cell engager in a Phase 1 trial in patients
  with CLDN6-expressing solid tumors. The company launched in 2022 with seed financing from Omega
  Funds, raised an oversubscribed $165M Series A, and closed a $52M Series A extension in February
  2026 with Andreessen Horowitz joining the syndicate. Third Arc Bio publishes no public API,
  developer portal, SDK or machine-readable specification — it is a therapeutics developer, not a
  software vendor.
image: https://thirdarcbio.com/thirdarc-og-image.png
url: https://raw.githubusercontent.com/api-evangelist/third-arc-bio/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
x-tier: profiled
x-tier-reason: enrichment-pass-no-api-surface
specificationVersion: '0.20'
created: '2026-08-30'
modified: '2026-08-30'
tags:
- Company
- Biotechnology
- Therapeutics
- Antibodies
- Oncology
- Immunology
- Life Sciences
- Clinical Stage
apis: []
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: DomainSecurity
  url: security/third-arc-bio-domain-security.yml
- type: Website
  url: https://thirdarcbio.com/
- type: PrivacyPolicy
  url: https://thirdarcbio.com/privacy-policy/
- type: TermsOfService
  url: https://thirdarcbio.com/terms-of-service/
- type: Blog
  url: https://thirdarcbio.com/news/
- type: Support
  url: mailto:info@thirdarcbio.com
- type: LinkedIn
  url: https://www.linkedin.com/company/third-arc-bio/
- type: LLMsTxt
  url: llms/third-arc-bio-llms.txt
x-enrichment:
  date: '2026-08-30'
  status: minimal
  artifacts_added: 3
  pass: local-v1
x-coverage:
  state: none
  reason: not-a-software-company
  detail: >-
    Third Arc Bio is a clinical-stage antibody therapeutics developer; thirdarcbio.com is a Gatsby
    static marketing site with only science, pipeline, team, news and policy pages, and every
    contract-discovery path (/openapi.json, /swagger.json, /api-docs, /docs, /developers, /api,
    /graphql, /llms.txt) plus every /.well-known/ document returns the site's 404 body, while
    api., developer., docs. and mcp. subdomains do not resolve in DNS.
  evidence:
  - url: https://thirdarcbio.com/
    status: 200
  - url: https://thirdarcbio.com/openapi.json
    status: 404
  - url: https://thirdarcbio.com/developers
    status: 404
  - url: https://thirdarcbio.com/.well-known/agent-card.json
    status: 404
  - url: https://thirdarcbio.com/.well-known/api-catalog
    status: 404
  checked: '2026-08-30'