Metastatic Breast Cancer by Circulating Tumor DNA

This study will evaluate the efficacy and safety of 6-mercaptopurine (6MP) in combination with methotrexate (MTX) in patients with breast or ovarian cancer who are known to have a BRCA (breast cancer gene) mutation.

This study will evaluate the efficacy and safety of 6-mercaptopurine (6MP) in combination with methotrexate (MTX) in patients with breast or ovarian cancer who are known to have a BRCA (breast cancer gene) mutation. 6MP is used instead of thioguanine(6TG) as it is converted to the same cytotoxic moiety as 6TG, ie. thioguanine nucleotides, but with reduced toxic effects. Low dose methotrexate is used in combination with 6MP as it promotes the formation of thioguanine nucleotides.