Stealth BioTherapeutics
Stealth BioTherapeutics (now Mighty Therapeutics) is a clinical-stage biopharmaceutical company developing mitochondria-targeted therapeutics for ultra-rare genetic and age-related diseases, with FDA-approved FORZINITY (elamipretide) for Barth syndrome and a pipeline spanning dry AMD, cardiac, and neurological indications.
- Company typePrivate
- Founded2007
- HeadquartersNewton, United States
- Headcount51–100
- GTM typeB2B
- OfferingHardware or Manufacturing
What Stealth BioTherapeutics does
Stealth BioTherapeutics, which rebranded to Mighty Therapeutics in 2025-2026, is a clinical-stage and now early-commercial biopharmaceutical company developing mitochondria-targeted therapeutics for rare genetic and age-related diseases of mitochondrial dysfunction. The company's core technology is a proprietary platform of small molecules designed to localize to mitochondria and improve mitochondrial function, with elamipretide (branded FORZINITY) as the lead asset. FORZINITY received FDA accelerated approval on September 19, 2025, as the first-ever approved treatment for Barth syndrome, an ultra-rare genetic condition affecting approximately 150 individuals in the United States. The clinical pipeline includes bevemipretide eye drops for dry age-related macular degeneration (Phase 1 enrollment complete, Phase 2 planned for late 2026), SBT-255 for cardiac conditions, SBT-272 for dry AMD (Phase 1 results shared at ARVO 2025), and SBT-589 for neurological disorders including Leigh syndrome (preclinical, supported by an MRC Business Engagement Fund grant awarded in 2026).
The company monetizes its lead product through a specialty pharmaceutical distribution model. FORZINITY is priced at up to approximately $800,000 annually per patient, reflecting the ultra-rare disease pricing paradigm. Exclusive US distribution is handled through AnovoRx Specialty Pharmacy (commercial availability from December 2025), supported by the Mito Assist patient financial assistance program. Revenue streams are therefore concentrated in pharmaceutical product sales for an ultra-rare indication, with the broader pipeline representing optionality on future indications. The customer base is composed entirely of patients with ultra-rare mitochondrial diseases — initially Barth syndrome, with potential expansion into POLG1-related disease, Leigh syndrome, dry AMD, and cardiac conditions of mitochondrial dysfunction. The company is headquartered in Newton, Massachusetts, employs 51-100 people, and has raised approximately $171M+ in disclosed funding rounds led by Morningside Ventures and Pivotal bioVenture Partners.
Stealth BioTherapeutics firmographics
Firmographics- Name
- Stealth BioTherapeutics
- Legal name
- Stealth BioTherapeutics Inc.
- Website
- https://mightytx.com/
- Company type
- Private
- Founded year
- 2007
- Operating status
- Operating
- Headcount range
- 51–100 employees
- Short description
- Stealth BioTherapeutics (now Mighty Therapeutics) is a clinical-stage biopharmaceutical company developing mitochondria-targeted therapeutics for ultra-rare genetic and age-related diseases, with FDA-approved FORZINITY (elamipretide) for Barth syndrome and a pipeline spanning dry AMD, cardiac, and neurological indications.
- Ownership category
- akta.pro rank
Stealth BioTherapeutics industry classification
Industry- Product category
- Mitochondrial Therapeutics
- NAICS
- Biological Product (except Diagnostic) Manufacturing (325414), Research and Development in Biotechnology (except Nanobiotechnology) (541714)
- SIC
- Pharmaceutical Preparations (2834)
- akta.pro primary industry
- Genetic & Genomic Rare Disease Therapeutics (HLAIAIAA)
- akta.pro secondary industries
- Rare Ophthalmology Disorder Therapies (HLAIAIAK), Enzyme Replacement & Metabolic Disorder Therapies (HLAIAIAB)
Keywords
Where Stealth BioTherapeutics is headquartered
LocationHeadquarters
- HQ city
- Newton
- HQ country
- United States
- HQ region
- North America
Markets served
Stealth BioTherapeutics business model
Business model- GTM type
- B2B
- Offering type
- Hardware or Manufacturing
- Cost components
- Technology or R&D, Personnel, Operations, Marketing or Sales, Supply Chain
Revenue model
- Pharmaceutical Product Sales: Revenue from commercial sale of FDA-approved drug Forzinity (elamipretide) for Barth syndrome, distributed through specialty pharmacy partners.
Pricing tiers
| Model | Billing | Price |
|---|---|---|
| Other | Annual | FORZINITY (elamipretide) injection for Barth syndrome |
Go-to-market motion1 record
Distribution channels1 record
Marketing channels3 records
Stealth BioTherapeutics product offering
Product offeringCore offering
Stealth BioTherapeutics (now Mighty Therapeutics) is a clinical-stage biopharmaceutical company developing mitochondria-targeted therapeutics for ultra-rare genetic mitochondrial diseases and age-related conditions. Its lead approved product is FORZINITY (elamipretide), the first FDA-accelerated approved treatment for Barth syndrome, with a clinical pipeline including bevemipretide eye drops for dry AMD and earlier-stage candidates (SBT-255, SBT-589, SBT-272) targeting cardiac, neurological, and ophthalmic conditions associated with mitochondrial dysfunction.
Product overview
Stealth BioTherapeutics (now Mighty Therapeutics) is a mitochondrial medicine company with a focused pipeline targeting mitochondrial dysfunction across rare and age-related diseases. The company's approved product is FORZINITY (elamipretide), which received FDA accelerated approval in September 2025 as the first treatment for Barth syndrome. The clinical pipeline includes bevemipretide eye drops for dry age-related macular degeneration (Phase 1 completed enrollment, Phase 2 planned for late 2026), SBT-255 for cardiac conditions, SBT-589 for neurological disorders including Leigh syndrome (with MRC grant support), and SBT-272 for dry AMD. The company supports patients through its Mito Assist patient assistance program.
Differentiator
Problem solved
Functional benefit
Brands
- Mito Assist™: Patient support program providing support and financial assistance to patients with Barth syndrome receiving FORZINITY treatment.
- FORZINITY™
Products and services
- FORZINITY (elamipretide) FDA-accelerated approved injectable therapy indicated for Barth syndrome. It is the first-ever approved mitochondria-targeted therapeutic, addressing an ultra-rare genetic condition with no prior disease-modifying treatment options. Distributed via specialty pharmacy to prescribing physicians for affected patients.
- Bevemipretide Eye Drops Clinical-stage non-invasive ophthalmic formulation for dry age-related macular degeneration (dry AMD), a condition affecting approximately 10 million individuals in the United States with no FDA- or EMA-approved treatments currently available.
- SBT-255 Pipeline compound in development for cardiac conditions associated with mitochondrial dysfunction.
- SBT-589 Pipeline candidate being evaluated in preclinical studies for neurological disorders, including Leigh syndrome, under an MRC-funded research collaboration.
- SBT-272 Clinical candidate for dry age-related macular degeneration with Phase I results shared at ARVO 2025.
- Mito Assist Patient support program offering financial assistance and support services to patients with Barth syndrome prescribed FORZINITY.
Quantifiable outcome
- Phase 3 NuPOWER results supporting elamipretide in POLG1-related mitochondrial disease
- +1 more outcomes
Companies that use Stealth BioTherapeutics
Customer profileNamed customers1 record
Segments2 records
Ideal customer profiles3 records
Stealth BioTherapeutics technology and API
TechnologyTechnology focussed Yes
API detail
- Has API
- No
- API docs
- API detail
Core technology
AI maturity
App detail
Feature5 records
Stealth BioTherapeutics partnerships and signals
Strategic signalPartnerships
Four partnerships are on record, tiered core and major.
- UK Medical Research Council (MRC)coreAwarded MRC Business Engagement Fund grant to support preclinical evaluation of SBT-589 in mouse models of Leigh syndrome. Part of broader efforts to accelerate clinical translation of mitochondrial therapies.
- Mary Lyon Centre at MRC HarwellmajorResearch collaboration partner for preclinical evaluation of SBT-589 in mouse models of Leigh syndrome, part of MRC National Mouse Genetics Network.
- University College LondonmajorAcademic research partner collaborating on mitochondrial disease research including preclinical evaluation of SBT-589 and prior clinical research in primary mitochondrial myopathy.
- AnovoRx Specialty PharmacycoreExclusive commercial distribution partner for FORZINITY (elamipretide) injection in the United States. Commercial product availability expected from December 2025 through this specialty pharmacy channel.
Scale indicators5 records
Recent moves7 records
Expansion highlights6 records
Stealth BioTherapeutics competitors and assessment
Company assessmentEmerging players
- Iveric Bio (Astellas): Developed an FDA-approved complement inhibitor for geographic atrophy in dry AMD, now part of Astellas. Direct competitive overlap with Stealth BioTherapeutics' bevemipretide dry AMD program.
- Homology Medicines: Clinical-stage genetic medicines company developing treatments for rare genetic diseases using proprietary platform technology. Comparable in platform-based approach to addressing rare genetic conditions with limited treatment options.
- Mereo BioPharma: Clinical-stage biopharmaceutical company focused on rare diseases with a pipeline of specialty therapeutics. Comparable ultra-rare disease focus and small-cap clinical development approach.
- Apellis Pharmaceuticals: Focused on complement inhibition therapies with an approved treatment for geographic atrophy secondary to dry AMD. Direct competitor in the dry AMD space where Stealth BioTherapeutics' bevemipretide is being developed.
Direct peers
- BioMarin Pharmaceutical: Specialized rare disease biopharmaceutical company with multiple approved enzyme replacement and gene therapy products. Comparable in business model of developing and commercializing ultra-rare disease therapeutics at premium prices through specialty distribution.
- Ultragenyx Pharmaceutical: Focused exclusively on rare and ultra-rare genetic diseases with multiple approved products and a deep clinical pipeline. Highly comparable target patient populations and ultra-rare disease commercialization approach to Stealth BioTherapeutics.
- Amicus Therapeutics: Develops therapies for rare metabolic diseases including Pompe and Fabry disease using proprietary biologics and small molecules. Comparable in targeting rare genetic metabolic disorders with disease-modifying mechanisms.
- PTC Therapeutics: Rare disease biopharmaceutical company with approved products for Duchenne muscular dystrophy and other genetic disorders. Comparable rare disease pipeline strategy and use of accelerated regulatory pathways.
- Sarepta Therapeutics: Specializes in genetic medicines for rare neuromuscular diseases with premium-priced approved products. Comparable business model of developing first-in-class therapies for small rare disease populations under accelerated regulatory pathways.
Broad incumbents
- Reata Pharmaceuticals: Developed novel mitochondria-targeted therapies (bardoxolone) for rare diseases including Alport syndrome, now part of Biogen. Closest historical peer in the mitochondrial-targeted therapeutics category, validating the commercial viability of this mechanism.
Market position
Strengths5 records
Weaknesses5 records
Competitive moat4 records
Key risks7 records
Key highlights7 records
Customer concentration
Stealth BioTherapeutics social profiles
Digital presenceStealth BioTherapeutics financial estimates
Financial estimateRevenue estimate
Valuation estimate
Stealth BioTherapeutics leadership team
Management profileNumber of profiles
Profiles5 records
Stealth BioTherapeutics funding detail
Funding detailFunding overview
Funding rounds9 records
Investors10 records
Funding detail is available on the Subscription and Enterprise plan.Contact sales →
Stealth BioTherapeutics M&A and investment
M&A and investmentM&A
Investments
M&A and investment is available on the Subscription and Enterprise plan.Contact sales →
Frequently asked questions about Stealth BioTherapeutics
What does Stealth BioTherapeutics do?
Stealth BioTherapeutics (now Mighty Therapeutics) is a clinical-stage biopharmaceutical company developing mitochondria-targeted therapeutics for ultra-rare genetic mitochondrial diseases and age-related conditions. Its lead approved product is FORZINITY (elamipretide), the first FDA-accelerated approved treatment for Barth syndrome, with a clinical pipeline including bevemipretide eye drops for dry AMD and earlier-stage candidates (SBT-255, SBT-589, SBT-272) targeting cardiac, neurological, and ophthalmic conditions associated with mitochondrial dysfunction.
Is Stealth BioTherapeutics a public or private company?
Stealth BioTherapeutics is a private company. It is classified as venture growth investor backed and is currently operating.
When was Stealth BioTherapeutics founded?
Stealth BioTherapeutics was founded in 2007. It employs 51 to 100 people.
Where is Stealth BioTherapeutics based?
Stealth BioTherapeutics is headquartered in Newton, United States, in the North America region.
How does Stealth BioTherapeutics make money?
One revenue line is on record: pharmaceutical Product Sales.
Who are Stealth BioTherapeutics's main competitors?
Emerging players on record are Iveric Bio (Astellas), Homology Medicines, Mereo BioPharma and Apellis Pharmaceuticals. Direct peers are BioMarin Pharmaceutical, Ultragenyx Pharmaceutical, Amicus Therapeutics, PTC Therapeutics and Sarepta Therapeutics. Reata Pharmaceuticals is listed as a broad incumbent.
Does Stealth BioTherapeutics have an API?
No public API is recorded for Stealth BioTherapeutics.
What industry is Stealth BioTherapeutics in?
Stealth BioTherapeutics's product category is Mitochondrial Therapeutics. Its primary akta.pro industry code is HLAIAIAA, Genetic & Genomic Rare Disease Therapeutics, with a secondary code of HLAIAIAK, Rare Ophthalmology Disorder Therapies. Its NAICS code is 325414 and its SIC code is 2834.