Motexafin gadolinium: a possible new radiosensitiser

Motexafin gadolinium (MGd, PCI-0120, Xcytrin, a metallotexaphyrin developed by Pharmacyclics, is a redox active drug that selectively targets tumour cells with a potential action as a radiosensitiser. In vitro and in vivo models showed radiation enhancement when radiation followed MGd administration. Phase I and II clinical studies showed that MGd was well-tolerated with a maximum-tolerated dose set at 6.3 mg/kg. Acute side effects of discolouration of the sclera, skin and urine are reversible. The clinical efficacy was determined in an international Phase III trial for brain metastases with a significant difference in time to neurological progression for lung cancer brain metastases in favour of MGd and whole brain radiation versus whole brain radiation only. For the treatment of glioblastoma multiforme, promising results are found in a Phase I trial with a median survival of 17.3 months. Further investigation of the combination of MGd and radiotherapy will be worthwhile.