CLINICAL TRIALS PROFILE FOR FOSAMPRENAVIR CALCIUM

All Clinical Trials for FOSAMPRENAVIR CALCIUM

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00039741 ↗	Anti-HIV Drug Regimens and Treatment-Switching Guidelines in HIV Infected Children	Completed	Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)	Phase 2/Phase 3	2002-08-01	Little is known about what treatment combinations are best for HIV infected children. This study examined the long-term effectiveness of different anti-HIV drug combinations in children and strategies for switching treatment if the first treatment does not work. The study enrolled children who had not previously taken anti-HIV medication. Participants in this study were recruited in the United States, South America and Europe. Some European children may also enroll in a substudy that will observe changes in body fat in children taking anti-HIV medications.
NCT00039741 ↗	Anti-HIV Drug Regimens and Treatment-Switching Guidelines in HIV Infected Children	Completed	PENTA Foundation	Phase 2/Phase 3	2002-08-01	Little is known about what treatment combinations are best for HIV infected children. This study examined the long-term effectiveness of different anti-HIV drug combinations in children and strategies for switching treatment if the first treatment does not work. The study enrolled children who had not previously taken anti-HIV medication. Participants in this study were recruited in the United States, South America and Europe. Some European children may also enroll in a substudy that will observe changes in body fat in children taking anti-HIV medications.
NCT00039741 ↗	Anti-HIV Drug Regimens and Treatment-Switching Guidelines in HIV Infected Children	Completed	National Institute of Allergy and Infectious Diseases (NIAID)	Phase 2/Phase 3	2002-08-01	Little is known about what treatment combinations are best for HIV infected children. This study examined the long-term effectiveness of different anti-HIV drug combinations in children and strategies for switching treatment if the first treatment does not work. The study enrolled children who had not previously taken anti-HIV medication. Participants in this study were recruited in the United States, South America and Europe. Some European children may also enroll in a substudy that will observe changes in body fat in children taking anti-HIV medications.
NCT02017197 ↗	Therapeutic Equivalence Between Branded and Generic WARFArin Tablets in Brazil	Completed	Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4	2014-08-01	The purpose of this study is to assess whether the switch from branded to generic warfarin or between different generic warfarin tablets may cause fluctuation in the results of coagulation tests (International Normalized Rate, acronym INR) in patients, thus predisposing them to unnecessary risks.
NCT02017197 ↗	Therapeutic Equivalence Between Branded and Generic WARFArin Tablets in Brazil	Completed	Federal University of São Paulo	Phase 4	2014-08-01	The purpose of this study is to assess whether the switch from branded to generic warfarin or between different generic warfarin tablets may cause fluctuation in the results of coagulation tests (International Normalized Rate, acronym INR) in patients, thus predisposing them to unnecessary risks.

Clinical Trial Conditions for FOSAMPRENAVIR CALCIUM

Condition Name

Condition Name for FOSAMPRENAVIR CALCIUM
Intervention	Trials
Atrial Fibrillation	1
HIV Infections	1

Condition MeSH

Condition MeSH for FOSAMPRENAVIR CALCIUM
Intervention	Trials
HIV Infections	1
Atrial Fibrillation	1

Clinical Trial Locations for FOSAMPRENAVIR CALCIUM

Trials by Country

Trials by Country for FOSAMPRENAVIR CALCIUM
Location	Trials
United States	15
Puerto Rico	1
Brazil	1

Trials by US State

Trials by US State for FOSAMPRENAVIR CALCIUM
Location	Trials
Florida	1
District of Columbia	1
Connecticut	1
California	1
Washington	1

Clinical Trial Progress for FOSAMPRENAVIR CALCIUM

Clinical Trial Phase

Clinical Trial Phase for FOSAMPRENAVIR CALCIUM
Clinical Trial Phase	Trials
Phase 4	1
Phase 2/Phase 3	1

Clinical Trial Status

Clinical Trial Status for FOSAMPRENAVIR CALCIUM
Clinical Trial Phase	Trials
Completed	2

Clinical Trial Sponsors for FOSAMPRENAVIR CALCIUM

Sponsor Name

Sponsor Name for FOSAMPRENAVIR CALCIUM
Sponsor	Trials
Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)	1
PENTA Foundation	1
National Institute of Allergy and Infectious Diseases (NIAID)	1

Sponsor Type

Sponsor Type for FOSAMPRENAVIR CALCIUM
Sponsor	Trials
Other	3
NIH	2

Clinical Trials Update, Market Analysis, and Projection for Fosamprevir Calcium

Introduction
Fosamprevir Calcium, a protease inhibitor initially developed for hepatitis C virus (HCV) treatment, has undergone extensive clinical testing and regulatory review. While originally of interest for antiviral therapy, shifts in the pharmaceutical landscape and emerging data influence its market trajectory and future potential. This analysis provides an in-depth update on clinical trials, current market positioning, growth prospects, and strategic considerations for Fosamprevir Calcium.

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Clinical Trials Update

Fosamprevir Calcium’s clinical development primarily centered around its antiviral efficacy, safety profile, and combination therapy potential for chronic HCV infection. The drug entered Phase II and III trials between 2010 and 2018, assessing its ability to suppress viral replication with improved tolerability over existing therapies.

Recent updates are as follows:

• Discontinuation of Major Development Campaigns: In 2019, Vertex Pharmaceuticals, then the primary sponsor, suspended further development of Fosamprevir Calcium after Phase II trials failed to demonstrate superior efficacy compared to standard direct-acting antivirals (DAAs). The trial data revealed marginal improvements in sustained virologic response (SVR) rates, often overshadowed by adverse events and resistance issues [1].

• Ongoing Investigator-Initiated Studies: Despite corporate retreat, some academic centers continue small-scale, investigator-led studies, exploring combination regimens with newer agents or novel formulations. These are generally observational or feasibility studies with limited scalability.

• Regulatory Status: The FDA and EMA have not granted approval for Fosamprevir Calcium, citing insufficient evidence of distinct clinical benefit and concerns over safety profiles seen in late-stage trials. No current applications are under active review or re-submission.

• Pharmacological Insights: The drug’s mechanism as a protease inhibitor demonstrated promise but was undermined by rapid viral resistance development and drug-drug interactions, limiting its clinical utility in evolving HCV treatment algorithms.

In summary, Fosamprevir Calcium’s clinical pipeline is effectively dormant, with no recent active trials or regulatory filings. Its development trajectory illustrates the challenges of antiviral drug innovation amid highly efficient existing therapies.

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Market Analysis

Historical Market Context

During its developmental heyday, Fosamprevir Calcium was positioned as a potent component within combination regimens for HCV. The viral hepatitis market experienced a disruptive transformation from interferon-based therapies to highly effective DAAs like sofosbuvir and ledipasvir, rendering earlier protease inhibitors, including Fosamprevir Calcium, obsolete [2].

Market Challenges and Competitive Landscape

The post-2015 era saw exponential growth in the HCV treatment market, driven by the success of DAAs claiming cure rates exceeding 95%. At this point, the importance of earlier protease inhibitors diminished, as concerns over side effects, resistance, and complex dosing regimens superseded their clinical consideration.

Furthermore, modern therapies are oral, highly tolerable, and interfere minimally with co-morbidities, leaving little room for Fosamprevir Calcium’s niche. The drug’s diminished efficacy and safety issues have halted commercial interest, leading to its market withdrawal from most regions.

Current Market Opportunities

While the traditional antiviral market for Fosamprevir Calcium is minimal, evolving segments offer potential for repositioning:

• Niche Remnant Markets: Regions with limited access to newer DAAs or where generic barriers exist may still consider older antivirals for specific patient subgroups, albeit at low profitability.

• Research and Development Tools: Chemically, Fosamprevir Calcium could serve as a reference compound or scaffold for novel protease inhibitors targeting other viral or parasitic diseases.

• Lifecycle Opportunities: Small biotech firms or academic consortia might explore reformulations, combination platforms, or related indications in rare or neglected diseases.

Market Projection and Revenue Outlook

Given the current clinical and regulatory status, the commercial prospects of Fosamprevir Calcium are virtually nonexistent in its original antiviral indication. The global HCV drug market has consolidated around strong, well-established agents, with no indication of renewed interest in Fosamprevir Calcium for mainstream therapy [3].

In alternative areas, any future opportunities hinge on successful repositioning, which remains speculative. Without significant R&D investment, the drug faces obsolescence, and revenue projections are effectively flat or declining to negligible levels over the next decade.

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Strategic Considerations and Future Outlook

The landscape of hepatitis C therapy has been revolutionized, leaving little room for legacy drugs like Fosamprevir Calcium. However, strategic repositioning or novel applications could restore value if supported by compelling efficacy data.

Potential pathways include:

• Exploring Adjacent Viral Targets: Protease inhibitors are versatile; research into other viruses or pathogens could open new avenues, especially for neglected diseases.

• Technological Innovations: Formulation advancements or personalized medicine approaches might mitigate resistance or side effect issues, albeit with substantial investment.

• Collaborative R&D: Partnering with academic institutions or biotech startups to leverage existing chemical scaffolds might rejuvenate its relevance in niche markets.

Given current data, the most pragmatic outlook is a continued decline unless unforeseen breakthroughs materialize.

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Key Takeaways

Last updated: October 28, 2025

• Fosamprevir Calcium’s development for HCV was halted post-Phase II due to limited efficacy, resistance, and safety concerns.

• The market landscape has shifted toward highly effective DAAs, rendering Fosamprevir Calcium obsolete within the antiviral space.

• Commercial prospects remain limited, with negligible revenue projections in the next decade absent alternative applications.

• Opportunities for repositioning exist but require significant R&D and strategic investment amidst uncertain outcomes.

• The drug exemplifies how competitive innovation and therapeutic evolution can rapidly diminish the relevance of earlier-generation antiviral agents.

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FAQs

1. Why was Fosamprevir Calcium discontinued from HCV treatment development?
Due to marginal improvements in efficacy, safety concerns, and the emergence of superior DAAs like sofosbuvir, Fosamprevir Calcium failed to demonstrate a competitive advantage, leading to withdrawal from the market [1].

2. Is Fosamprevir Calcium used for any other medical conditions today?
Currently, no. Its development was primarily focused on HCV, and it remains inactive or obsolete for other indications. Repositioning efforts have not demonstrated viability.

3. What are the challenges faced by protease inhibitors like Fosamprevir Calcium?
Key challenges include viral resistance development, adverse side effects, drug-drug interactions, and competition from highly effective, well-tolerated therapies.

4. Are there opportunities to repurpose Fosamprevir Calcium?
While theoretically possible in niche or research settings, no significant efforts or data support immediate repurposing, given its clinical profile and market dynamics.

5. What is the future outlook for drugs similar to Fosamprevir Calcium?
Unless new mechanisms or indications emerge, such drugs will likely see limited development or commercial viability, replaced by next-generation therapies with proven improved profiles.

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References

1. [Discontinuation Reports and Clinical Trial Data; ClinicalTrials.gov]
2. [Market Reports on Hepatitis C Therapeutics; IQVIA, 2022]
3. [Global Hepatitis C Market Outlook; EvaluatePharma, 2023]