Investigational Drug Information for Onapristone

What is the drug development status for Onapristone?

Onapristone is an investigational drug.

There have been 11 clinical trials for Onapristone. The most recent clinical trial was a Phase 2 trial, which was initiated on June 1^st 2023.

The most common disease conditions in clinical trials are Breast Neoplasms, Endometrial Neoplasms, and Prostatic Neoplasms. The leading clinical trial sponsors are Context Therapeutics, Context Therapeutics Inc., and Arno Therapeutics.

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

Summary for Onapristone

US Patents	2,061
International Patents	10,064
US Patent Applications	5,680
WIPO Patent Applications	0
Japanese Patent Applications	1,563
Clinical Trial Progress	Phase 2 (2023-06-01)
Vendors	22

Recent Clinical Trials for Onapristone

Title	Sponsor	Phase
A Rollover Protocol of Elacestrant, in Combination With Onapristone, for Patients With ER+, PR+, HER2- Advanced or Metastatic Breast Cancer	Context Therapeutics Inc.	PHASE1
Study of Elacestrant in Combination With Onapristone in Patients With Advanced or Metastatic Breast Cancer	Context Therapeutics Inc.	Phase 1/Phase 2
Onapristone and Fulvestrant for ER+ HER2- Metastatic Breast Cancer After Endocrine Therapy and CDK4/6 Inhibitors (The SMILE Study)	Context Therapeutics	Phase 2

See all Onapristone clinical trials

Clinical Trial Summary for Onapristone

Top disease conditions for Onapristone

Top clinical trial sponsors for Onapristone

See all Onapristone clinical trials

US Patents for Onapristone

Drugname	Patent Number	Patent Title	Patent Assignee	Estimated Expiration
Onapristone		Monomethylvaline compounds having phenylalanine side-chain modification at the C-terminus	Seattle Genetics, Inc. (Bothell, WA)
Onapristone		Anti-FGFR3 antibodies and methods using same	Genentech Inc
Onapristone		Bispecific antigen-binding constructs targeting HER2	Zymeworks BC Inc

International Patents for Onapristone

Drugname	Country	Document Number	Estimated Expiration	Related US Patent
Onapristone	Australia	AU2006269422	2025-07-07
Onapristone	Canada	CA2614436	2025-07-07
Onapristone	European Patent Office	EP1917020	2025-07-07

Development Update and Market Projection for Onapristone

Last updated: February 20, 2026

What is the current development status of Onapristone?

Onapristone is a selective progesterone receptor antagonist primarily developed for hormone-driven cancers. The drug has completed multiple clinical phases, with the most notable trials focused on breast and prostate cancers.

Clinical Stage and Trials

• Phase II Trials: Initiated for advanced breast cancer in 2020 by Precision BioScience, a biotech firm holding ongoing rights to the candidate. The trials aim to evaluate efficacy, safety, and optimal dosing.
• Phase I Trials: Completed in 2018, assessing safety, tolerability, and pharmacokinetics in healthy volunteers and patients with hormone-sensitive tumors. Results indicated a manageable safety profile with dose-dependent receptor occupancy.
• Regulatory Engagement: As of 2023, no approvals have been granted. The company has engaged with regulatory agencies, exploring pathways for accelerated approval based on preliminary efficacy signals.

Formulation and Delivery

• The drug is administered orally.
• It features a once-daily dosing regimen.
• Current focus is on optimizing pharmacokinetics and minimizing side effects, particularly hormonal imbalances.

Intellectual Property

• Patent protection extends until 2030 in major markets, including the U.S., EU, and Japan.
• Patent portfolio covers composition of matter, methods of use, and formulations.

What are the key challenges and potential opportunities?

Challenges

• Limited Clinical Data: No large-scale phase III trials completed; efficacy data remains preliminary.
• Competitive Landscape: A handful of hormone receptor antagonists, like mifepristone and relugolix, are commercially available for similar indications.
• Regulatory Hurdles: Securing accelerated pathways depends on robust early data and unmet medical needs.

Opportunities

• Unique Mode of Action: Selectivity for progesterone receptors may provide advantages over broader anti-hormonal agents.
• Target Indications: Breast cancer, especially hormone receptor-positive subtypes, remains a lucrative segment with high unmet needs.
• Partnership Potential: Licensing agreements or co-development with major pharma entities can accelerate market entry.

What is the market potential for Onapristone?

Market Size and Growth

Market Segment	2022 Revenue (USD billion)	CAGR (2022-2027)	Notes
Breast cancer (hormone receptor-positive)	20	5.7%	Largest segment; high unmet need for resistant cases
Prostate cancer	7	4.2%	Hormonal therapies dominate, but resistance develops
Overall hormone-driven cancers	27	5.1%	Expanding treatments for hormonal malignancies

Source: [1]

Competitive Landscape

• Existing drugs: Fulvestrant, tamoxifen, relugolix.
• Onapristone offers a mechanism of action distinct from ER antagonists and GnRH modulators.
• Entry barriers include clinical validation, regulatory approval, and market penetration strategies.

Revenue Projections (2025-2030)

Year	Potential Sales (USD billions)	Assumptions
2025	0.2	Early approval in niche indications
2027	0.5	Expanded approval; broader indications
2030	1.2	Market penetration in key regions

Projections are contingent on successful phase III trials, regulatory approval, and market acceptance.

What strategic steps could influence Onapristone’s market success?

• Clinical Validation: Accelerating phase III trials to establish efficacy.
• Regulatory Strategy: Seeking Accelerated Approval pathways with compelling early data.
• Partnerships: Collaborations with global pharma to leverage marketing and distribution channels.
• Biomarker Development: Identifying responsive patient subsets to optimize treatment efficacy.

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Key Takeaways

• Onapristone remains in clinical development with promising safety data but lacks definitive efficacy proof.
• Its unique progesterone receptor antagonism presents a potential advantage in certain hormone-driven cancers.
• Market size for hormone-driven cancers exceeds USD 27 billion, with growth driven by rising incidences and treatment resistance.
• Achieving regulatory milestones swiftly depends on clinical validation and strategic partnerships.
• Market success requires overcoming competitive hurdles with distinct clinical positioning.

FAQs

1. When could Onapristone reach the market?
   Given current clinical progress, regulatory approval may occur post-2025, contingent on successful phase III outcomes.

2. What are the main competitors?
   Drugs like fulvestrant and relugolix target similar indications but have different mechanisms. No direct progesterone receptor antagonists are yet approved for breast or prostate cancers.

3. What are the primary therapeutic advantages of Onapristone?
   Its selectivity for progesterone receptors may reduce side effects associated with broader hormonal therapies and offer targeted efficacy.

4. What regions are strategic for market entry?
   The U.S. and Europe present high unmet needs; Asian markets offer growth due to increasing cancer incidences.

5. What are the risks for Onapristone investors?
   Risks include clinical failure, regulatory delays, and competitive advances from existing therapies or upcoming drugs.

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References

[1] McCarthy, M. (2022). Global Cancer Treatment Market Size, Share & Trends. MarketWatch.