6-Thioguanosine (or thioguanosine) is a metabolite of 6-thioguanine, an immunosuppressant and anticancer prodrug, and plays a major role in the prodrug's overall photoreactivity. 6-Thioguanosine has been shown to induce DNA damage and cell death upon exposure to UVA radiation, which is correlated to the significant increase in skin cancers following prolonged treatment with thiopurine prodrug. Also existed experiments where 6-thioguanosine was used to treat idiopathic myocardial hypertrophy and where it showed clinical value in cancer chemotherapy.