Failed 2025

    iTeos Therapeutics

    Big-pharma partnerships aren't insurance. GSK, Merck and Roche have all walked away from TIGIT programs. If your thesis is 'partner data will validate us,' the partner's decision terminates you.

    TL;DR — Failure Post-Mortem

    iTeos Therapeutics was a Biotech / Oncology startup founded in 2011 in Belgium. It raised $600M+ (public) before collapsing in 2025 — 14 years of runway burned. IdeaProof's AI Failure Score: 66/100, driven by gsk terminated tigit partnership after negative phase 2 lung cancer data. The shutdown affected employees, investors, and the broader Biotech / Oncology ecosystem. This case study breaks down the timeline, root causes, competitors that won, and replicable lessons for founders validating similar ideas today.

    Why did iTeos Therapeutics fail?

    iTeos Therapeutics failed in 2025 after 14 years of operation, losing $600M+ (public) in raised capital. The root cause was gsk terminated tigit partnership after negative phase 2 lung cancer data. Key lesson: Big-pharma partnerships aren't insurance. GSK, Merck and Roche have all walked away from TIGIT programs. If your thesis is 'partner data will validate us,' the partner's decision terminates you.

    Verifiable facts
    Sourced
    Founded → Closed

    2011 → 2025

    Funding Raised

    $600M+ (public)

    Industry

    Biotech / Oncology

    Country

    Belgium

    IdeaProof AI Failure Score

    66/100
    Market Fit Risk
    70
    Burn Rate Risk
    75
    Founder Risk
    45

    What Happened: The Timeline

    🚀

    2011

    iTeos Therapeutics founded in Belgium. Positioned in biotech / oncology.

    💰

    2011-2013

    Raises $600M+ (public) from Public shareholders (Nasdaq: ITOS); MPM Capital, Novo Holdings previously.

    ⚠️

    2024

    Warning signs emerge: gsk tigit termination.

    💀

    2025

    Shutdown announced. Root cause: gsk terminated tigit partnership after negative phase 2 lung cancer data.

    Root Causes

    GSK TIGIT termination
    Class-wide TIGIT mechanism failure
    Single-asset biotech dependency
    No second oncology program to pivot to

    iTeos Therapeutics was a Belgian oncology biotech IPO'd on Nasdaq in 2020 with a lead anti-TIGIT antibody, belrestotug, partnered with GSK in a $2B+ collaboration. In May 2025 GSK announced it was ending the TIGIT program after negative Phase 2 data. Two weeks later iTeos announced it would wind down operations, sell assets and return as much of its $600M+ cash pile to investors as possible. The failure follows Roche and Merck exits from TIGIT — an entire immuno-oncology mechanism has now been widely questioned. iTeos is a case study in how a single mechanism-of-action can take out multiple companies simultaneously.

    Causal Chain

    Derived · heuristic

    This is our reading of the causal chain — separated from the verifiable facts above. Timeline dates, funding numbers and filings are facts (see methodology); root / proximate / terminal attribution is judgement based on public evidence.

    Root cause

    A combination of demand-side, execution, and capital-market pressures that this record documents without isolating a single dominant driver.

    Contributing factors
    • GSK TIGIT termination
    • Class-wide TIGIT mechanism failure
    • Single-asset biotech dependency
    • No second oncology program to pivot to
    Proximate cause

    2024: Warning signs emerge: gsk tigit termination.

    Terminal event

    2025: Shutdown announced. Root cause: gsk terminated tigit partnership after negative phase 2 lung cancer data.

    Base rates

    External sources

    A single failure is an anecdote. These base rates give you the denominator — how common this outcome is across all startups matching iTeos Therapeutics's profile. Sources are third-party; we do not restate them as our own claims.

    ~97%
    industry

    of venture-backed consumer hardware startups do not reach a profitable exit within 10 years — hardware requires atypical capital efficiency to survive.

    PitchBook Emerging Tech Research (2023)
    ~70%
    industry

    of digital-health startups fail to reach breakeven; reimbursement complexity + regulatory approvals extend runway needs beyond typical VC horizons.

    Rock Health State of Digital Health (2023)
    ~90%
    all

    of startups ultimately fail — including ~10% that fail in the first year and the rest across the following decade.

    Startup Genome / CB Insights aggregate (2024)
    ~35%
    all

    of new US employer businesses survive past their 10th year (Bureau of Labor Statistics BED series).

    US Bureau of Labor Statistics — BED (2024)
    ~35%
    stage

    of Series A rounds ever graduate to Series B; the rest run out of runway or pivot without a follow-on.

    CB Insights Venture Capital Funnel (2023)

    Key Lessons Learned

    1. GSK TIGIT termination

    GSK TIGIT termination — a recurring pattern across biotech / oncology failures. Validate this risk before you scale.

    2. Class-wide TIGIT mechanism failure

    Class-wide TIGIT mechanism failure — a recurring pattern across biotech / oncology failures. Validate this risk before you scale.

    3. Single-asset biotech dependency

    Single-asset biotech dependency — a recurring pattern across biotech / oncology failures. Validate this risk before you scale.

    Frequently Asked Questions

    Sources & Confidence

    Every data point is tagged with its source type and our confidence in it. How we grade sources.

    Additional references
    Fierce Biotech

    Could This Failure Have Been Prevented?

    IdeaProof's AI validates market demand, competitive positioning, and business model viability in minutes — catching the exact issues that sank iTeos Therapeutics.

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    Spotted a factual error?

    Approved corrections are published in the public changelog with attribution.

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