This is a randomized, double-blind, within-subject placebo controlled study to evaluate the safety and efficacy of various doses of STP705 administered as intradermal Injection in subjects with hypertrophic scar. The goals are to determine the recommended Phase 2 dose, the pharmacokinetics and pharmacidynamics parameters, and conduct analysis of biomarkers common to the scar formation pathway.

This single-center, randomized, double-blind, within-subject placebo controlled study is designed to evaluate the safety and efficacy of various doses of STP705 administered as intradermal injection in subjects with linear hypertrophic scar.

Twenty four subjects will be divided equally among 3 cohorts (20, 30 and 40 μg/cm2/day dose level) of 8 subjects each. Each subject will receive both active (STP705) and control (Placebo) treatment twice a week for a total of 4 weeks. The total length of linear hypertrophic scar will be divided equally for treatment with STP705 and placebo. STP705 and Placebo will be injected intradermal every 1 cm length on the hypertrophic scar.

Subjects will be confined to clinic or research unit for 24 hours post-dosing after the first treatment administration for the serial PK assay and the blood sample will be collected at the following post-dosing times: 30 min, 1 hr, 2 hrs, 3 hrs, 4 hrs, 5hrs, 6 hrs, 8 hrs, 12 hrs, 16 hrs, 24 hrs, 32 hrs and 36 hrs. Post-dosing ECG will be performed 6 hours (±1 hr) after the first study drug administration and vital signs will be monitored every 2h till 12h post-administration. Adverse events and medications will be monitored throughout the study.

Inclusion Criteria:

1. Subject is able to understand and willing to conform to the study procedures and has signed the informed consent form (ICF).

2. Subject is male or female, between the ages of 18 and 60 years, inclusive.

3. Subject with a hypertrophic scar that meet all of the following criteria:

   • linear scar, ≥5 to ≤40 cm in length (Cohort A), ≥5 to ≤50 cm in length (Cohort B), ≥5 to ≤60 cm in length (Cohort C)
   • present for minimum 6 months and no greater than 24 months
   • located anywhere in the body except on the face or front of neck
   • resulting from surgical or traumatic injury

4. Subject is judged, by the Investigator, to be healthy as evidenced by lack of clinically significant abnormal findings on medical history, physical examination, electrocardiogram, vital signs, and clinical laboratory tests.

5. Subject is willing and able to complete the entire course of the trial and to comply with the trial instructions.

6. Subject, if female of child-bearing potential, has a negative serum pregnancy test at screening and a negative urine pregnancy test at prior to treatment and willing to use acceptable methods of contraception (birth control pills, barriers, or abstinence) throughout the study.

Exclusion Criteria:

1. Subjects identified as having keloid or burn scars
2. Subjects who are positive for hepatitis B surface antigen (HbsAg), hepatitis C antibody and HIV.
3. Concurrent use of corticosteroids (including inhaled steroids) and COX-2 inhibitors
4. Are immuno-compromised (HIV infected, cancer and other disease affecting the basal immune response)
5. Clinically significant cardiovascular, pulmonary, renal, endocrine, hepatic, neurological, psychiatric, immunological, gastrointestinal, hematological, or metabolic disease that is, in the opinion of the Investigator, not stabilized or may otherwise impact the results of the study.
6. Known allergy or hypersensitivity to the study drug(s) or one of the ingredients of the formulation.
7. Any infection or wound in the area to treat.
8. Female subjects who are pregnant or breast-feeding.
9. Participation in a clinical study involving administration of an investigational compound within the past 30 days.
10. Existence of any surgical, medical or laboratory condition that, in the judgment of the clinical investigator, might interfere with the safety, distribution, metabolism or excretion of the drug.