Rhodamine-123: therapy for hormone refractory prostate cancer, a phase I clinical trial

Rhodamine-123, a lipophilic, cationic, rhodocyanine dye, has been reported to have carcinoma selective toxicity in vitro and in vivo. This phase I clinical trial established the safety and pharmacokinetics of Rhodamine-123 administered to men with hormone refractory prostate cancer. A single dose toxicity study of Rhodamine-123 determined the maximum tolerated dose. A multiple dose toxicity study assessed the safety of Rhodamine-123 at the maximum tolerated dose level. Transient and variable toxicities noted following Rhodamine-123 infusion resolved within 6 hours following infusion. Pharmacokinetic analyses of sera showed no accumulation of drug with repeated monthly administrations. Drug retention was confirmed in prostatic tissue following Rhodamine-123 administration. PSA doubling times lengthened variably suggesting drug efficacy but the data were not statistically significant. The maximum tolerated dose of Rhodamine-123 is 96 mg/m2. The drug can be safely administered at monthly intervals without detectable drug accumulation in serum. Rhodamine-123 is retained by prostatic tumor tissue.