CLINICAL TRIALS PROFILE FOR CYSTEAMINE HYDROCHLORIDE

505(b)(2) Clinical Trials for cysteamine hydrochloride

This table shows clinical trials for potential 505(b)(2) applications. See the next table for all clinical trials

Trial Type	Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
New Formulation	NCT00001736 ↗	New Cysteamine Eye Drops Formulation to Treat Corneal Crystals in Cystinosis	Completed	National Eye Institute (NEI)	Phase 1	1998-05-01	This study will evaluate the safety and effectiveness of a new formulation of eye drops used to treat cystine crystals that form in the corneas of patients with cystinosis. Cystinosis is an inherited disease caused by a defective enzyme, in which excessive amounts of the amino acid cystine accumulate in the body. Among others, symptoms include poor growth and development of kidney failure. In addition, after 10 to 20 years, the cornea-the outside covering of the eye over the iris and pupils-becomes so packed with cystine crystals that small, painful breaks may develop. This corneal condition is treated with cysteamine eye drops. This study is designed to provide additional information about this medication that the Food and Drug Administration requires before approving it for marketing. The study will examine, in two separate but simultaneous investigations, the safety and effectiveness of a new cysteamine formulation. In both studies, before treatment begins, patients will have a complete eye examination, and photographs of the eye will be taken using a bright flash. Safety Study Children and adults currently enrolled in a cystinosis study at the National Institutes of Health may participate in this trial. They will receive the current cysteamine formulation in one eye and the new preparation in the other eye. The drops will be given every hour during waking hours. Patients will be observed daily for the first week of treatment and will be called at 2 weeks and 4 weeks to check on side effects, if any. At 6 months, they will undergo a repeat eye examination. Patients (or their parents) will keep a daily diary recording the condition of each eye. Effectiveness Study Children and adults from Ann Arbor, Michigan, LaJolla, California, and the NEI clinic may be enrolled in this study. Participants will receive medication as described above for the safety trial. They will be observed daily for the first week and will have repeat eye examinations, including photographs, at months 3, 6, 9 and 12 to see if the crystals have decreased. Patients will keep a daily diary of the condition of both eyes.
New Formulation	NCT00010426 ↗	Randomized Study of New Formulation Ophthalmic Cysteamine Hydrochloride for Corneal Cystine Accumulation in Patients With Cystinosis	Completed	Leadiant Biosciences, Inc.	N/A	1999-12-01	OBJECTIVES: I. Determine the proportion of patients with cystinosis who experience a serious adverse effect when treated with a new formulation of cysteamine hydrochloride for corneal cystine accumulation. II. Determine the proportion of patients with a reduction in corneal crystal density of 1.00 unit when treated with this regimen.
New Formulation	NCT00010426 ↗	Randomized Study of New Formulation Ophthalmic Cysteamine Hydrochloride for Corneal Cystine Accumulation in Patients With Cystinosis	Completed	Sigma Tau Pharmaceuticals, Inc.	N/A	1999-12-01	OBJECTIVES: I. Determine the proportion of patients with cystinosis who experience a serious adverse effect when treated with a new formulation of cysteamine hydrochloride for corneal cystine accumulation. II. Determine the proportion of patients with a reduction in corneal crystal density of 1.00 unit when treated with this regimen.
New Formulation	NCT00010426 ↗	Randomized Study of New Formulation Ophthalmic Cysteamine Hydrochloride for Corneal Cystine Accumulation in Patients With Cystinosis	Completed	FDA Office of Orphan Products Development	N/A	1999-12-01	OBJECTIVES: I. Determine the proportion of patients with cystinosis who experience a serious adverse effect when treated with a new formulation of cysteamine hydrochloride for corneal cystine accumulation. II. Determine the proportion of patients with a reduction in corneal crystal density of 1.00 unit when treated with this regimen.

All Clinical Trials for cysteamine hydrochloride

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00001213 ↗	Cysteamine Eye Drops to Treat Corneal Crystals in Cystinosis	Completed	National Eye Institute (NEI)	Phase 2	1986-04-01	Cystinosis is an inherited disease that results in poor growth and kidney disease, among other things. The damage to the kidneys and other organs is thought to be due to accumulation of cystine inside the cells of various body tissues. This chemical also accumulates in the cornea-the covering of the eye over the pupil and iris. After 10 to 20 years, the corneas of some patients become so packed with crystals that the surfaces may become irregular, occasionally causing small, painful breaks. Patients enrolled in a NIH study on cystinosis are receiving the drug cysteamine. Taken by mouth, this drug reduces cystine in some tissues, but not in the cornea. This study began in 1986 to test whether cysteamine eye drops could prevent or reduce corneal cystine crystals in these patients. The drops have been very effective in removing crystals and reducing pain in patients who take the medication as directed. Patients who do not take the medication as prescribed do not benefit. After the effectiveness of the drops was proven, the main purpose was modified to continue to evaluate the long-term safety and effectiveness of cysteamine eye drops for treating cystine crystals in the corneas of patients with cystinosis until the drops are approved by the Food and Drug Administration (FDA). When the New Drug Application (NDA) for the Sigma-Tau standard formulation is granted, this protocol will be terminated.
NCT00001736 ↗	New Cysteamine Eye Drops Formulation to Treat Corneal Crystals in Cystinosis	Completed	National Eye Institute (NEI)	Phase 1	1998-05-01	This study will evaluate the safety and effectiveness of a new formulation of eye drops used to treat cystine crystals that form in the corneas of patients with cystinosis. Cystinosis is an inherited disease caused by a defective enzyme, in which excessive amounts of the amino acid cystine accumulate in the body. Among others, symptoms include poor growth and development of kidney failure. In addition, after 10 to 20 years, the cornea-the outside covering of the eye over the iris and pupils-becomes so packed with cystine crystals that small, painful breaks may develop. This corneal condition is treated with cysteamine eye drops. This study is designed to provide additional information about this medication that the Food and Drug Administration requires before approving it for marketing. The study will examine, in two separate but simultaneous investigations, the safety and effectiveness of a new cysteamine formulation. In both studies, before treatment begins, patients will have a complete eye examination, and photographs of the eye will be taken using a bright flash. Safety Study Children and adults currently enrolled in a cystinosis study at the National Institutes of Health may participate in this trial. They will receive the current cysteamine formulation in one eye and the new preparation in the other eye. The drops will be given every hour during waking hours. Patients will be observed daily for the first week of treatment and will be called at 2 weeks and 4 weeks to check on side effects, if any. At 6 months, they will undergo a repeat eye examination. Patients (or their parents) will keep a daily diary recording the condition of each eye. Effectiveness Study Children and adults from Ann Arbor, Michigan, LaJolla, California, and the NEI clinic may be enrolled in this study. Participants will receive medication as described above for the safety trial. They will be observed daily for the first week and will have repeat eye examinations, including photographs, at months 3, 6, 9 and 12 to see if the crystals have decreased. Patients will keep a daily diary of the condition of both eyes.
NCT00002110 ↗	A Phase II/III Study of Cysteamine (Mercaptoethylamine) and Zidovudine for the Treatment of HIV Disease	Completed	Mylan Laboratories	Phase 2	1969-12-31	To determine the safety and tolerance of low-dose versus high-dose cysteamine administered concurrently with zidovudine (AZT). To determine the pharmacokinetics and effects on immune function and viral load in patients receiving these drug regimens.
NCT00010426 ↗	Randomized Study of New Formulation Ophthalmic Cysteamine Hydrochloride for Corneal Cystine Accumulation in Patients With Cystinosis	Completed	Leadiant Biosciences, Inc.	N/A	1999-12-01	OBJECTIVES: I. Determine the proportion of patients with cystinosis who experience a serious adverse effect when treated with a new formulation of cysteamine hydrochloride for corneal cystine accumulation. II. Determine the proportion of patients with a reduction in corneal crystal density of 1.00 unit when treated with this regimen.

Clinical Trial Conditions for cysteamine hydrochloride

Condition Name

Condition Name for cysteamine hydrochloride
Intervention	Trials
Cystinosis	12
Cystic Fibrosis	2
Corneal Cystine Crystals	1
Leigh Syndrome	1

Condition MeSH

Condition MeSH for cysteamine hydrochloride
Intervention	Trials
Cystinosis	12
Fanconi Syndrome	3
Cystic Fibrosis	2
Non-alcoholic Fatty Liver Disease	2

Clinical Trial Locations for cysteamine hydrochloride

Trials by Country

Trials by Country for cysteamine hydrochloride
Location	Trials
United States	53
France	5
Netherlands	4
United Kingdom	4
Italy	2

Trials by US State

Trials by US State for cysteamine hydrochloride
Location	Trials
California	11
Texas	6
Ohio	5
Illinois	5
Georgia	5

Clinical Trial Progress for cysteamine hydrochloride

Clinical Trial Phase

Clinical Trial Phase for cysteamine hydrochloride
Clinical Trial Phase	Trials
PHASE2	2
Phase 4	2
Phase 3	4

Clinical Trial Status

Clinical Trial Status for cysteamine hydrochloride
Clinical Trial Phase	Trials
Completed	18
RECRUITING	5
Terminated	3

Clinical Trial Sponsors for cysteamine hydrochloride

Sponsor Name

Sponsor Name for cysteamine hydrochloride
Sponsor	Trials
Horizon Pharma USA, Inc.	7
Raptor Pharmaceuticals Inc.	7
Thiogenesis Therapeutics, Inc.	3

Sponsor Type

Sponsor Type for cysteamine hydrochloride
Sponsor	Trials
Industry	27
Other	18
NIH	8

Cysteamine Hydrochloride Clinical Trials Update, Market Analysis, and Market Projection (2026–2036)

Last updated: July 26, 2026

Cysteamine hydrochloride is a long-established, small-molecule therapy used primarily for nephropathic cystinosis. Pipeline activity is concentrated in (1) oral delayed-release delivery systems that seek to improve adherence and cystine control and (2) regulatory strategy around drug product updates and potential generic entry risk management. Commercial projections hinge on cystinosis patient counts, payer coverage for specialty drugs, and uptake of improved-release formulations versus legacy dosing.

---

What is cysteamine hydrochloride used for and what is the clinical evidence base?

Answer (featured snippet): Cysteamine hydrochloride treats nephropathic cystinosis by reducing intracellular cystine in lysosomes, slowing renal deterioration and other complications. Clinical evidence includes historically established efficacy for cystine depletion and improvements in renal outcomes, supported by long-term follow-up and real-world use patterns.

Key clinical endpoints used in cystinosis programs

• Leukocyte cystine levels (primary pharmacodynamic marker in many programs)
• Time to renal decline, CKD progression, and renal replacement therapy
• Tubular function metrics and organ complication progression
• Safety outcomes tied to chronic dosing (GI effects, dosing tolerability)

Common dosing context that shapes trials

Cysteamine products are used chronically and require strict adherence. Trials and product updates generally focus on:

• Improving bioavailability and tolerability
• Reducing frequency or improving release profile
• Maintaining cystine depletion durability between doses

---

What clinical trials are currently active or recently updated for cysteamine hydrochloride?

Answer (featured snippet): Current clinical-trials activity for cysteamine hydrochloride largely reflects drug product lifecycle work (formulation, bioequivalence, pharmacokinetics, and adherence-focused endpoints) and investigator-led studies tied to cystinosis care pathways rather than new mechanism-of-action efforts.

Typical trial designs used in cysteamine lifecycle development

• Open-label PK and pharmacodynamic (cystine depletion) studies in cystinosis patients
• Comparative studies versus reference cysteamine products, often with leukocyte cystine outcomes
• Safety and tolerability cohorts emphasizing long-term chronic administration

Trial update themes seen in the cysteamine drug class

• Adherence improvements through altered release profiles and dosing convenience
• Expanded subgroup inclusion such as pediatric versus adult cohorts
• Product switching studies to quantify cystine control stability

Trial reporting cadence and what to watch

• PK bridging outcomes that correlate with sustained cystine depletion
• Adverse event rates across chronically dosed populations
• Dropout and adherence metrics that predict payer and physician adoption

---

How many patients have nephropathic cystinosis and what does that imply for cysteamine hydrochloride demand?

Answer (featured snippet): Nephropathic cystinosis is ultra-rare. Addressable demand is driven by the prevalence of diagnosed patients in treated geographies and the fraction who sustain long-term cystine-lowering therapy.

Demand drivers

• Diagnosed prevalence versus undiagnosed pool
• Pediatric initiation and persistence on therapy
• Switching between cysteamine products based on tolerability and coverage
• Geographic access to specialized nephrology care

Demand constraints

• Lifelong treatment requirement reduces churn once patients are stable
• Small absolute patient volumes cap near-term revenue growth absent major diagnosis expansions

---

What is the market size for cysteamine hydrochloride and how does pricing vary by region?

Answer (featured snippet): Market revenue is dominated by specialty pricing in major markets and is highly sensitive to payer reimbursement, specialty pharmacy channel structure, and product-specific pricing rather than broad volume expansion.

Market segmentation that matters commercially

• By geography: US, EU5, UK, and rest-of-world specialty systems
• By product form: immediate-release versus delayed-release variants
• By patient line: incident (new diagnosis) versus prevalent (ongoing therapy)

Pricing and contracting dynamics in rare disease specialty drugs

• Payer-specific formularies and step-edits can shift uptake
• Specialty pharmacy distribution affects net pricing via contracting and rebates
• Physician preference is strongly influenced by tolerability and dosing simplicity

---

Which companies market cysteamine hydrochloride products and how concentrated is the competitive landscape?

Answer (featured snippet): The cysteamine market is typically concentrated among companies controlling marketed cysteamine formulations and those holding exclusivity for specific delivery systems, with competition increasingly shaped by drug product line extensions and potential generic entry mechanics.

Competitive factors

• Product switching based on cystine control and GI tolerability
• Institutional procurement patterns at cystinosis specialty centers
• Coverage decisions that favor a limited number of products per payer

What determines share shifts

• Evidence of comparable or improved cystine depletion with better adherence
• Real-world tolerability and adherence outcomes
• Contracting and formulary placement

---

How does cysteamine hydrochloride compare with other cystinosis therapies in efficacy and adoption?

Answer (featured snippet): Cysteamine remains the primary cystine-depleting therapy class for nephropathic cystinosis. Adoption depends more on delivery profile, tolerability, and adherence than on differences in mechanism since alternatives are limited.

Delivery system differences that drive market positioning

• Release profile and dosing frequency influence adherence
• Side-effect profile influences persistence
• Pharmacodynamic “between-dose” cystine control determines perceived effectiveness

Adoption levers

• Demonstrated maintenance of cystine depletion
• Evidence in pediatric cohorts and tolerability in long-term use
• Payer and specialty center alignment

---

What patent and exclusivity issues protect cysteamine hydrochloride products?

Answer (featured snippet): Protection for cysteamine class products is typically layered: compound or use patents may be long expired, while drug product patents, formulation patents, and regulatory exclusivities can extend market protection for specific marketed formulations.

Key protection types to map in diligence

• Orange Book listed patents for specific NDCs (US)
• Formulation and dosing regimen patents (composition and release technology)
• Method-of-use patents (rare, but can exist for specific regimens or patient subsets)
• Pediatric exclusivity and other regulatory exclusivities (product-specific)

What this means for competitive entry

• Generic entry risk depends on whether ANDA submissions can avoid listed patents
• Formulation changes are the most common basis for switching and non-interchangeability

---

What is the Orange Book status of cysteamine hydrochloride and which patents are most relevant to generic entry?

Answer (featured snippet): Orange Book status is tied to specific approved cysteamine drug products and their listed patents, with the most relevant entries typically being formulation, method-of-use, and dosing regimen patents that cover the marketed dosage form.

Litigation and Paragraph IV risk mapping (what usually matters)

• Any active or historical Paragraph IV litigation for cysteamine products
• Settlement terms that control “at-risk” launch dates
• Country-by-country differences in patent enforceability and registration

---

When does cysteamine hydrochloride lose exclusivity and what generic launch scenarios exist?

Answer (featured snippet): Exclusivity loss is product-specific and depends on the last-to-expire combination of regulatory exclusivity and Orange Book patent expirations for each marketed dosage form.

Generic launch scenario logic (market impact)

• If formulation patents expire earlier than method-of-use, entry may be delayed by litigation
• If settlement exists, entry dates can be hard-bounded by agreement terms
• If bioequivalence requires formulation matching, adoption barriers remain even after approval

---

What formulation patents and delivery system patents matter most for cysteamine uptake?

Answer (featured snippet): For chronic cysteamine therapy, formulation and release technology patents often matter more commercially than compound patents, because payer and clinician preference tracks with tolerability and cystine control across dosing intervals.

Common technical patent themes in cysteamine product estates

• Enteric or delayed-release coatings and delivery materials
• Particle size, granulation, and release kinetics controls
• Combination dosing methods and patient adherence regimens
• Stability and manufacturing process claims tied to consistent release

---

What clinical trial evidence would support switching to a different cysteamine hydrochloride product?

Answer (featured snippet): Switching decisions generally rely on PK bridging plus pharmacodynamic evidence of sustained cystine depletion, backed by tolerability and adherence outcomes in pediatric and adult cohorts.

Switching evidence categories

• Leukocyte cystine control curves across dosing intervals
• Safety profile during the first months after switching
• Adherence measures such as missed-dose rates or discontinuation
• Real-world persistence to therapy over 6 to 24 months

---

How big is revenue exposure to product switching, competitive entry, and payer restriction?

Answer (featured snippet): Revenue exposure is concentrated in (1) the ability to hold prevalent patients and (2) the ability to win incident patients at diagnosis, both of which are sensitive to formulary coverage and net pricing after competitive pressure.

Revenue sensitivity model (structure)

• Base demand: diagnosed nephropathic cystinosis prevalent population
• Incidence: new diagnoses per year
• Retention: persistence on therapy
• Share: product-level share among available cysteamine formulations
• Net price: list price adjusted by rebates and specialty contracting

Key risks

• If a competing formulation improves tolerability, share can shift quickly at specialty centers
• Payer formulary restrictions can shift net price and channel access
• Generic entry can compress net price if product interchangeability is recognized clinically

---

Market projection for cysteamine hydrochloride (2026–2036): growth, scenarios, and milestones

Answer (featured snippet): For ultra-rare cystinosis therapy, volume growth is slow and revenue growth depends mainly on net pricing, retention, and product mix shift. The dominant scenario is modest growth with periodic step-changes when switching or competitive pressures occur.

Scenario framework

• Base case: gradual incident diagnosis growth, stable persistence, modest net price changes, steady share for the incumbent product(s)
• Bull case: favorable formulary expansions, improved adherence-linked outcomes, increased uptake of preferred delivery formats
• Bear case: earlier-than-expected competitive entry or payer restriction, leading to net price compression and share losses

What milestones will move the projection

• Regulatory approvals of new cysteamine product forms or updated labeling that expands use
• Patent expiry events and outcomes of any patent challenges that enable at-risk or non-at-risk entry
• Trial readouts that demonstrate stronger cystine control durability or improved tolerability

Projection drivers to quantify (how revenue should be modeled)

• Diagnosed patient counts by geography and age group
• Expected annual incidence and survival/CKD progression patterns that sustain prevalence
• Product-level cystine control performance translating to persistence
• Net price trajectory by payer segment

(Note: specific numeric projections, patient counts, NDC-level Orange Book lists, patent expiration dates, and company shares require product-level dataset extraction from Orange Book, FDA labeling, and trial registries. Without that product-specific extraction, numeric projections would not meet an accuracy standard for high-stakes decisions.)

---

Key Takeaways

• Cysteamine hydrochloride demand is driven by ultra-rare nephropathic cystinosis prevalence and lifelong adherence, not by broad-market uptake.
• Clinical trial updates in the cysteamine class are concentrated on delivery and lifecycle work that ties pharmacokinetics to durable leukocyte cystine depletion and tolerability.
• Competitive and exclusivity dynamics are product-specific and hinge on formulation patents and Orange Book listings tied to specific dosage forms.
• Market projection should be built on diagnosed prevalence, incident growth, retention, and product mix shifts, with step-change risk around patent expiry and formulary contracting.

---

FAQs

1. What pharmacodynamic markers are used to assess cysteamine hydrochloride in cystinosis trials?
2. How does cysteamine delivery profile (immediate vs delayed release) affect adherence and cystine control?
3. What Orange Book patent categories most often delay generic entry for cysteamine products?
4. How do settlement agreements with generic challengers typically affect launch timing in rare-disease specialty drugs like cysteamine?
5. Which pediatric-specific data are most important for cysteamine product labeling changes and payer approvals?

---

References

1. FDA Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations (current edition).
2. ClinicalTrials.gov (cysteamine hydrochloride and nephropathic cystinosis search results, current listings).
3. FDA labels and prescribing information for marketed cysteamine products (as published).