Maximum tolerated dose study

The intraperitoneal (IP) acute and subchronic maximum tolerated doses (MTD) of CPX-POM were determined in fasted male C57BL/6 mice under study conditions according to the principles of Good Laboratory Practices (GLP). In the acute MTD phase, mice were given a single IP dose of CPX-POM. Doses were given under a flexible dosing regimen adopted from OECD Acute Oral Toxicity Test Guideline 425, Up-and-Down Acute Toxicity Procedure⁵⁸. Doses were based on the tolerability, as determined by clinical observations, of the previous dose. Animals were observed for a minimum of two hours post-dose. Subsequent doses were adjusted based on observations of drug-related adverse effects (if any) from the previous dose. Dosing was staggered with five mice studied per dose group. Parameters examined included mortality, morbidity, clinical observations, and body weights. In dose cohort 1, IP doses were administered at a volume of 20 mL/kg resulting in a dose of 940 mg/kg as CPX-POM; in dose cohort 2, IP doses were administered at a volume of 10 mL/kg resulting in a dose of 470 mg/kg as CPX-POM; in dose cohort 3, IP doses were administered at a volume of 15 mL/kg resulting in a dose of 705 mg/kg as CPX-POM. Based on clinical observations from the first three treatment groups it was determined that additional dose groups were unnecessary. In the subchronic MTD phase, once-daily IP doses of CPX-POM were administered for 10 consecutive days to three treatment groups of ten mice each. Vehicle was administered IP once daily to a control group of ten mice as well. Dose levels for the subchronic MTD phase were selected based on the determination of the acute MTD. IP doses of test article were administered at volumes of 2.5 mL/kg, 5 mL/kg, and 10 mL/kg, resulting in doses of 117.5 mg/kg, 235 mg/kg, and 470 mg/kg, respectively, as CPX-POM. Doses were administered volumetrically based on the most recent body weight of the animal. Consistent with the acute MTD phase of this study, parameters examined included mortality/morbidity, clinical observations, and body weights. In addition, necropsies were performed on each animal with kidneys, liver, urinary bladder, and urinary tract tissues collected. Based on the absence of gross pathology findings, these tissues were not further processed.