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ST-246

Phase 2

Orthopoxviral Disease | Small molecule | Infectious Disease |SIGA Technologies Inc.|Last Updated: Sep 11, 2026

Success Probability

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Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials1
Total Enrollment107

FDA Designations

No designations recorded

Clinical trial landscape

ST-246 · 2 trials · 2 indications

Phase 2 1Phase 1 1
NCT00907803Safety, Tolerability, Pharmacokinetics (PK) of the Anti-Orthopox Drug, ST-246Orthopoxviral Disease
COMPLETED107 Analytics
PHASE2COMPLETED
Safety, Tolerability, Pharmacokinetics (PK) of the Anti-Orthopox Drug, ST-246
Orthopoxviral DiseaseUnlock trial analytics

Study Endpoints

Primary Endpoints

Number of Study Participants Who Tolerated a Single Daily Oral ST-246 Dose as Determined by Safety Parameter Changes According to the DAIDS (Division of Acquired Immunodeficiency Syndrome) Adverse Events (AE) Grading Table.
Days 1 to 14; then 24, 48, 72, 96 and 120 hours and 4 weeks after final dose

Subjects were administered a single, daily oral dose of ST-246 (400 or 600 mg)and changes in safety parameteres were monitored. Safety parameters included adverse events, vital signs, physical examinations, laboratory tests (hematology, blood chemistry, and urinalysis) and electrocardiograms. The DAIDS AE grading table is a list of common terms and severity (intensity) of parameters used to describe adverse events occurring in NIAID-sponsored clinical studies/trials.

Number of Study Participants Who Tolerated ST-246 (250, 400 or 800mg) as Determined by Changes in Safety Parameters, According to the Division of Acquired Immunodeficiency Syndrome (DAIDS) Adverse Events (AE) Grading Table
Days 1, 6, 14-16, 21-24, 28-31, and 51-53

Evaluated safety parameters included: 1. physical examination/vital signs 2. electrocardiograms (heart rate, PR interval, QRS duration, QT interval, and QTc Bazett) 3. laboratory safety tests (hematology, chemistry, urinalysis) 4. adverse events (AEs) For a)-c), statistical values (mean, standard deviation, median, minimum, maximum) and changes from baseline (Day 1 pre-dose) to each time-point, were compared to laboratory normal reference ranges. If values for a)-d) were a Grade 3 or higher (in DAIDS AE Table)and ST-246-related, they were considered severe and significant, respectively.

Secondary Endpoints

Evaluation of Pharmacokinetic Parameters to Assess Interventions: Cmax
Day 1 post-dose
Evaluation of Pharmacokinetic Parameters to Assess Interventions: Tmax
Day 1 post-dose
Evaluation of Pharmacokinetic Parameters to Assess Interventions: AUCtau
Day 1 post-dose
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Study Design & Arms

AllocationRANDOMIZED
MaskingDOUBLE
ModelPARALLEL
PurposeOTHER

Treatment Arms

ArmTypeDescription
ST-246 400 mgEXPERIMENTALST-246 400mg (2 x 200 mg Capsules) Orally Once Daily for 14 days
ST-246 600 mgEXPERIMENTALST-246 600 mg (3 x 200 mg Capsules) Orally Once Daily for 14 days
PlaceboPLACEBO_COMPARATORMatching Placebo capsules, Orally Once Daily for 14 days
ST-246EXPERIMENTAL250 mg, 400 mg or 800 mg of ST-246 given once daily for 21 days

Interventions

NameTypeDescription
ST-246 400 mgDRUGCapsules, 400 mg daily for 14 days
ST-246 600 mgDRUGCapsules, 600 mg daily for 14 days
PlaceboDRUGCapsules, once daily for 14 days
ST-246DRUG250 mg, 400 mg or 800 mg capsules given once daily for 21 days
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Eligibility Criteria

Age Range18 Years to 75 Years
SexALL
Healthy VolunteersYes
Study Sites3

Inclusion Criteria: 1. 18 - 75 yrs 2. Healthy volunteer 3. Ability to consent 4. Available for clinical follow-up for study 5. Not taking other medications 6. Adequate venous access 7. Using adequate birth control; negative pregnancy test 8. Able and willing to avoid alcohol for screening and study...

Countries:United States
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Frequently asked questions about ST-246

What is ST-246 used for?

ST-246 is an investigational small molecule being developed for Orthopoxviral Disease and for use in healthy volunteers. It is being studied as a potential treatment for orthopoxviral infections, which include diseases such as smallpox and monkeypox. The drug is currently in clinical development and is not yet approved.

Who makes ST-246?

ST-246 is being developed by SIGA Technologies Inc., a biopharmaceutical company traded on the stock exchange under the ticker symbol SIGA. The company is conducting clinical trials to evaluate the safety, tolerability, and pharmacokinetics of ST-246 in healthy volunteers and in patients with Orthopoxviral Disease.

What phase is ST-246 in?

ST-246 is in clinical development, with completed trials in Phase 1 and Phase 2. The Phase 1 trial evaluated safety, tolerability, and pharmacokinetics over 21 days in healthy volunteers, while the Phase 2 trial assessed safety, tolerability, and pharmacokinetics in healthy volunteers for Orthopoxviral Disease. ST-246 is investigational and not yet approved.

What clinical trials is ST-246 in?

ST-246 has been studied in two completed clinical trials. NCT00431951 was a Phase 1, escalating, multiple-dose trial in healthy volunteers. NCT00907803 was a Phase 2 trial evaluating the safety, tolerability, and pharmacokinetics of the anti-orthopox drug ST-246. Both trials were conducted in the United States.

Is ST-246 FDA approved?

ST-246 is not FDA approved. It is an investigational drug currently in clinical development. Clinical trials have been completed to evaluate its safety and tolerability, but it has not yet received approval from the FDA for any indication. The drug remains under investigation for Orthopoxviral Disease.