A strain of Staphylococcus epidermis that’s common on healthy human skin may be protective against some types of skin cancer, according to findings from a study published in Science Advances.

The study, which was conducted in mice, found that a strain of S. epidermis produces 6-N-hydroxyaminopurine (6-HAP), a molecule that impairs DNA synthesis and prevents the development and spread of cancer tumors. However, not every strain produces 6-HAP: mice without 6-HAP-producing S. epidermis still developed tumors from UV exposure.

To test the intervention, mice received IV injections of 6-HAP every 48 hours for two weeks and were then transplanted with melanoma cells. Their tumor size was suppressed by more than 50% compared to control mice, and they exhibited no toxic effects from the treatment.

Researchers indicated that further studies are needed to understand how 6-HAP is produced, whether it can be used to prevent cancer, or whether lack of 6-HAP increases cancer risk.