Cancer Research UK trial looks at 6-MP in BRCA-mutated cancers

A Phase II clinical trial funded by Cancer Research UK (CRUK) is exploring whether combination therapy with the immunosuppressive 6-MP (6-mercaptopurine, Purinethol) may offer a new option for women with advanced breast or ovarian cancer caused by faulty BRCA1 or BRCA2 genes. According to CRUK, around one in every 800 women in the UK carries a faulty BRCA1 gene and one in 500 has a faulty BRCA2 gene. Mutations in these genes are thought to account for about 2-5% of all breast cancer cases.
Specifically, the combination of 6-MP and another chemotherapy treatment, methotrexate, could help women with BRCA-deficient cancers who are resistant either to platinum-based chemotherapy drugs such as cisplatin or to the newer PARP inhibitors.
CRUK says, Cell-based laboratory studies have suggested that the thiopurine class of drugs, which includes 6-MP, is effective at killing BRCA-deficient cancer cells even after they have developed resistance to treatments such as PARP inhibitors and cisplatin.
Launched at the University of Oxford’s Experimental Cancer Medicine Centre (ECMC), the new study aims to recruit 65 patients at 10 centres around the UK. All of these patients will have advanced breast or ovarian cancer and will be known carriers of either BRCA1 or BRCA2 gene mutations.
6-MP is normally used to treat acute lymphocytic leukaemia, although it may also be prescribed for other conditions such as Crohn’s disease or ulcerative colitis.