A phase 1 trial of intravenous 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) in patients with advanced solid tumours
Horsley L., Cummings J., Middleton M., Ward T., Backen A., Clamp A., Dawson M., Farmer H., Fisher N., Halbert G., Halford S., Harris A., Hasan J., Hogg P., Kumaran G., Little R., Parker GJM., Potter P., Saunders M., Roberts C., Shaw D., Smith N., Smythe J., Taylor A., Turner H., Watson Y., Dive C., Jayson GC.
Background: 4-(N-(S-glutathionylacetyl)amino) phenylarsenoxide (GSAO) is a water-soluble mitochondrial toxin that binds to adenine nucleotide translocase in the inner mitochondrial membrane, thereby targeting cell proliferation. This phase 1 study investigated safety, dose-limiting toxicities (DLTs), maximum tolerated dose (MTD) and pharmacokinetics (PK) of GSAO as a daily 1-h infusion for 5 days a week for 2 weeks in every three. Pharmacodynamics of GSAO was evaluated by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and circulating markers of angiogenesis. Methods: Patients with advanced solid tumours received GSAO in a dose-escalation trial according to a standard '3 + 3' design that was guided by toxicity and, for the final dose escalation, by arsenic PK data. Results: A total of 34 patients were treated with GSAO across 9 dose levels (1.3-44.0 mg/m2). Treatment was well tolerated with few adverse events. An additional three patients were enrolled at the 12.4 mg/m 2 dose level following a DLT of derangement of liver function tests (grade 4). At the 44.0 mg/m2 dose level, two out of three patients had DLTs (reversible encephalopathy; paroxysmal atrial fibrillation). Conclusions: The MTD of GSAO was 22.0 mg/m2/day. There was no biomarker evidence from DCE-MRI or circulating markers of angiogenesis of an anti-vascular effect of GSAO. © 2013 Springer-Verlag Berlin Heidelberg.