Suramin for breast and prostate cancer: a pilot study of intermittent short infusions without adaptive control.

Background: Suramin has shown promising activity against prostate and breast cancer but is severely neurotoxic. Complex adaptive pharmacokinetics have previously been used to adjust doses. We have undertaken a pilot study to assess the feasibility of administering suramin to outpatients with advanced cancer, using simple peak and trough monitoring.
Patients and Methods: Nine patients with cancer refractory to conventional therapy were studied, eight with breast cancer and one with prostate cancer. Two received continuous infusions of suramin 350 mg/m2/day through an indwelling central venous catheter. Both sustained axillary vein thromboses. Subsequent patients received suramin 500 mg/m2 as a one hour intravenous infusion thrice weekly until a trough serum level of 200 micrograms/ml was achieved. Treatment was repeated at 8 week intervals. Serum suramin levels were checked before and after each dose.
Results: Suramin treatment was well tolerated. Despite peak serum levels of up to 506 micrograms/ml, no serious toxicity was seen. No tumour responses were seen.
Conclusions: We conclude that suramin can be safely and conveniently administered to outpatients by intermittent infusion without using complex adaptive dosing strategies. Suramin merits further study in less heavily pretreated breast cancer patients.