This research is looking at the safety of an investigational medication called TOP-N53 for people with systemic sclerosis, a condition where the skin and sometimes internal organs become thick and hard. The study is for adults aged 18 to 69 who have painful fingertip wounds, also known as digital ulcers. Participants can still be on a stable dose of Sildenafil, a medication sometimes used for blood flow issues.

In this study, participants will receive either the investigational medication or a placebo, which is a look-alike substance that has no active medication. The study lasts up to 31 days and will include up to 8 clinic visits, with 2 possible phone check-ins. Doctors will make sure the treatment is safe and check its effects on symptoms like blood flow, itch, and pain.

• Participants must be able to follow instructions and not have certain medical conditions that could make the study unsafe for them.
• Participants cannot have very severe skin thickening or other serious health issues.
• Pregnant or breastfeeding women cannot take part, and certain medications cannot be used during the study.