Investigational Drug Information for Epacadostat

What is the drug development status for Epacadostat?

Epacadostat is an investigational drug.

There have been 56 clinical trials for Epacadostat. The most recent clinical trial was a Phase 3 trial, which was initiated on December 15^th 2017.

The most common disease conditions in clinical trials are Carcinoma, Neoplasms, and Carcinoma, Non-Small-Cell Lung. The leading clinical trial sponsors are Incyte Corporation, Merck Sharp & Dohme Corp., and National Cancer Institute (NCI).

There are zero US patents protecting this investigational drug and zero international patents.

Summary for Epacadostat

US Patents	1,082
International Patents	2,698
US Patent Applications	2,739
WIPO Patent Applications	808
Japanese Patent Applications	249
Clinical Trial Progress	Phase 3 (2017-12-15)
Vendors	64

Recent Clinical Trials for Epacadostat

Title	Sponsor	Phase
An Umbrella Study to Determine the Safety and Efficacy of Various Monotherapy or Combination Therapies in Neoadjuvant Urothelial Carcinoma	Incyte Corporation	Phase 2
Safety and Efficacy of Retifanlimab (INCMGA00012) Alone or in Combination With Other Therapies in Participants With Advanced or Metastatic Endometrial Cancer Who Have Progressed on or After Platinum-based Chemotherapy.	European Network for Gynaecological Oncological Trial groups(ENGOT)	Phase 2
Safety and Efficacy of Retifanlimab (INCMGA00012) Alone or in Combination With Other Therapies in Participants With Advanced or Metastatic Endometrial Cancer Who Have Progressed on or After Platinum-based Chemotherapy.	GOG Foundation	Phase 2

See all Epacadostat clinical trials

Clinical Trial Summary for Epacadostat

Top disease conditions for Epacadostat

Top clinical trial sponsors for Epacadostat

See all Epacadostat clinical trials

US Patents for Epacadostat

Drugname	Patent Number	Patent Title	Patent Assignee	Estimated Expiration
Epacadostat		Bicyclic fused pyrimidine compounds as TAM inhibitors	Incyte Corporation (Wilmington, DE)
Epacadostat		.beta.-substituted .beta.-amino acids and analogs as chemotherapeutic agents and uses thereof	Quadriga Biosciences, Inc. (Los Altos, CA)
Epacadostat		1,2,5-oxadiazoles as inhibitors of indoleamine 2,3-dioxygenase	Incyte Corp , Incyte Holdings Corp
Epacadostat		Synergistic combination of immunologic inhibitors for the treatment of cancer	The University of Chicago (Chicago, IL)
Epacadostat		Tank-binding kinase inhibitor compounds	Gilead Sciences, Inc. (Foster City, CA)

International Patents for Epacadostat

Drugname	Country	Document Number	Estimated Expiration	Related US Patent
Epacadostat	World Intellectual Property Organization (WIPO)	WO2017027717	2035-08-12
Epacadostat	Argentina	AR105592	2035-08-03
Epacadostat	Australia	AU2016302243	2035-08-03
Epacadostat	Canada	CA2994404	2035-08-03
Epacadostat	China	CN108026026	2035-08-03

Summary:
Epacadostat (INCB024360), an IDO1 enzyme inhibitor developed by Incyte, has experienced significant setbacks in clinical development. Originally aimed at cancer immunotherapy, its development was curtailed after Phase 3 trial failures for melanoma. Market projections have shifted downward due to these failures, but interest persists in combination therapies and new indications, which could sustain future growth.

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What Is the Development Status of Epacadostat?

Epacadostat was designed to inhibit indoleamine 2,3-dioxygenase 1 (IDO1), an enzyme that modulates immune response by breaking down tryptophan into kynurenine. Elevated IDO1 activity correlates with immune evasion in tumors.

• Indications: Primarily targeted at advanced melanoma, non-small cell lung cancer, renal cell carcinoma, and other solid tumors.

• Clinical Trials:

Last updated: February 16, 2026

• Phase 3: Incyte conducted ECHO-301/KEYNOTE-252, combining epacadostat with pembrolizumab (Keytruda) for melanoma.
• Outcome: The trial failed to meet its primary endpoint; median progression-free survival (PFS) no better than pembrolizumab alone.
• Impact: Incyte halted further development for melanoma and shifted focus away from monotherapy.

Current Status (2023): No active registration for late-stage trials involving epacadostat. Development efforts pivot to biomarker-driven combination therapies.

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What Were the Key Clinical Trial Results?

Trial	Phase	Combination	Result	Outcome
ECHO-301/KEYNOTE-252	3	Epacadostat + pembrolizumab	No significant improvement in PFS or OS	Terminated
Other trials (various solid tumors)	Early	Various combinations	Mixed or inconclusive	Many discontinued or suspended

The failure was attributed to insufficient inhibition of IDO1’s role in immune evasion or compensatory pathways in tumors. This cast doubt on monotherapy efficacy and discouraged further investment in related indications.

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What Are Market Implications and Projections?

Pre-Clinical and Early-Stage Interest

Despite Phase 3 failures, research into IDO1 inhibition continues, notably:

• Combination Therapies: Trials combining IDO1 inhibitors with checkpoint inhibitors, chemotherapy, and targeted therapies.
• Biomarker Identification: Focus on patient subsets with high IDO pathway activity.

Market Size and Forecast

• Pre-Failure Projections: The global cancer immunotherapy market was expected to reach USD 150 billion by 2030, with IDO1 inhibitors accounting for a significant share.
• Post-Failure Adjustments: Market size expectations reduced by approximately 30%. The IDO1 inhibitor segment may be valued at USD 2-5 billion within immuno-oncology by 2027, contingent on successful combination strategies.

Key Market Drivers:

• Rising R&D investments in combination regimens.
• Increased understanding of tumor microenvironment modulation.
• Regulatory interest in companion diagnostics for patient stratification.

Competition and Future Outlook

• Other IDO1 inhibitors: Gilead’s navoximod (GDC-0919), which also saw clinical setbacks.
• Alternative approaches: Kynurenine pathway modulators, such as TDO inhibitors, are under development.

Regulatory Environment

Regulators maintain cautious stance following the ECHO-301 results. Future approvals depend on biomarker-driven data, with the FDA emphasizing patient stratification.

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What Are the Main Challenges for Future Development?

• Efficacy Concerns: Lack of clear evidence for the benefit of IDO1 inhibition alone or in current combination regimens.
• Biomarker Validation: Identifying predictive markers to select responsive populations remains complex.
• Market Competition: Emergence of alternative immune modulation strategies reduces reliance on IDO1 inhibitors.
• Regulatory Uncertainty: Need for tangible proof of clinical benefit to justify continued investment.

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What Are Opportunities for Resurgence?

• Novel Combination Strategies: Use with vaccines, other co-inhibitory molecules, or metabolic pathway inhibitors.
• New Indications: Exploring roles in infectious diseases or autoimmune conditions where IDO1 activity is implicated.
• Next-Generation Inhibitors: Development of more potent or selective compounds that overcome current limitations.

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Key Takeaways

• Development of epacadostat has been halted in melanoma following failed Phase 3 trials.
• The broader IDO1 inhibitor market has contracted but retains potential via combination therapies.
• Success depends on biomarker validation, patient stratification, and innovative combinations.
• Regulatory agencies are cautious, demanding more compelling evidence.
• Future growth may emerge from novel indications and next-generation compounds.

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Frequently Asked Questions

1. Will Incyte or other companies resume development of epacadostat?
Unlikely, given the failure in late-stage melanoma. However, early-stage trials for other indications or combinations may continue if promising biomarker data emerges.

2. Are there alternative IDO1 inhibitors still in development?
Yes. Gilead (navoximod) and other companies are pursuing different compounds, though market momentum has waned.

3. Can epacadostat find a niche in non-oncology indications?
Potentially. Areas like autoimmune diseases or chronic infections could provide alternative pathways, but clinical data is limited.

4. How does the failure impact the broader immunotherapy landscape?
It tempers enthusiasm for IDO1 as a standalone target; however, combination strategies remain viable.

5. What are the key factors for future success in IDO pathway targeting?
Biomarker-driven patient selection, innovative combination regimens, more potent next-generation inhibitors, and regulatory alignment.

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Citations:
[1] Incyte Corporation. "Epacadostat Clinical Trials." Accessed 2023.