Failed 2025

    iTeos Therapeutics: How the Death of TIGIT Ended a Public Belgian Oncology Biotech

    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) (capital raised, not a verified loss) before shutting down in 2025, 14 years after founding. IdeaProof's Failure Score is 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. $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

    Interpretive pattern, not company-specific evidence: this chain is derived from the recorded failure reason and may apply to many companies with the same reason.Timeline dates, funding numbers and filings are facts (see methodology); root / proximate / terminal attribution is judgement based on public evidence.

    Root cause

    GSK TIGIT termination

    Contributing factors
    • 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.

    ~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)

    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.

    After iTeos Therapeutics: hubs, comparisons and deep dives

    Compare the validation, funding and go-to-market choices that separate survivors from failures like iTeos Therapeutics.