A phase I and pharmacokinetic (PK) study of high dose selenomethionine (SLM) in combination with irinotecan (IRI) in patients with advanced solid tumors

2080 Background: SLM, an organic selenium (Se) compound, potentiates IRI activity, protects against toxicity, and allows dose-escalation of IRI in pre-clinical models. IRI dose-escalation in mice models was possible only in association with serum Se concentrations > 1200ng/ml. We initiated a phase I study of daily SLM with weekly IRI to investigate: 1) the maximum tolerated dose (MTD) of IRI when combined with high dose SLM; 2) the pharmacokinetics (PK) of both compounds. Methods: IRI was escalated in a standard 3+3 design. SLM was administered at a fixed dose of 2200 μg/day starting 1 week before the 1st dose of IRI. IRI was administered intravenously weekly x 4 repeated every 6 weeks (1cycle). Dose level (DL) 1 and DL2 consisted of IRI 125mg/m2 and 160mg/m2 respectively. Blood for Se was drawn on days 1, 2, 8, 15, 29 and 50 (and later where possible). Results: 10 evaluable pts were treated on study (M/F: 6/4; median age: 59; ECOG 0/1: 3/7; prior chemo: 10). At DL2, 3 out of 4 pts had G3 diarrhea (DLT). ...