Effect of Curcumin on Dose Limiting Toxicity and Pharmacokinetics of Irinotecan in Patients With Solid Tumors

Treatment Plan This is a single-center, two-part, open label prospective study to define the maximum tolerated dose (MTD) of curcumin plus irinotecan and the pharmacokinetic effects of curcumin on irinotecan metabolism in patients with advanced colorectal cancer. Each cycle of irinotecan is defined as 28 days, with a dose of irinotecan administered on D1 and D15. The study will have two parts: Part 1 comprises the dose escalation portion of the study and Part 2 comprises the MTD expansion and pharmacokinetic study. Patients will be recruited from the GI oncology clinic of the North Carolina Cancer Hospital. After obtaining informed consent, patients will be entered into Part 1 of the study until the MTD has been defined. During study Part 1, patients will be given a 4 day run-in of curcumin prior to irinotecan dosing. The planned dose levels of curcumin will be 1, 2, 3, and 4 grams per day. Irinotecan will be dosed at 200 mg/m2 IV on days 1 and 15.46 Additional antineoplastic agents will not be allowed during the trial. Two patients will be enrolled at each dose level until a DLT occurs, beginning with the lowest dose level and increasing the level only after 2 patients have successfully completed a full irinotecan cycle at that dose level. Part 2 will investigate the effect of curcumin on irinotecan and SN-38 pharmacokinetics. We will expand the cohort of patients at the defined MTD in part 1. Patients will receive irinotecan alone for a single dose (D1). Curcumin, at the MTD, will be started on D11 and continued until the end of the cycle (D28). Irinotecan will be administered again on D15. Blood samples will be collected on the days of irinotecan infusion (D1 and D15) as follows: prior to treatment with irinotecan (baseline), immediately following the end of irinotecan infusion, and at 0.5, 1, 1.5, 2, 4, 6, and 24 hours following the end of the irinotecan infusion for irinotecan and SN-38 PK. All patients will continue on curcumin + irinotecan for further cycles until disease progression or toxicity occurs at the discretion of the treating physician (see section 5.6). For patients in study Part 1, we will offer to escalate the curcumin dose to the highest dose level that has been safely completed until an MTD has been estimated. Treatment Assignment Part 1: At the end of the screening period, eligible patients are assigned in cohorts of 2 at escalating doses until the first Dose Limiting Toxicity(DLT) is observed. DLT determination will be made based on one cycle in initial cohorts of 2. As much information as possible is used in the initial cohorts of 2. After the first DLT is observed, DLT rates at each dose are estimated using isotonic regression. For that, proportions of DLTs are computed at each dose first, then, if there is a violation of monotonicity, data at the violating dose levels are pooled and new proportions computed. The estimated DLT rate at the current dose is used to determine whether the dose will be increased, decreased or remained unchanged. The dose is to remain unchanged if the estimated DLT rate at the current dose is between \[0.17, 0.33\]; the dose is decreased if the estimated DLT rate is higher than 0.33; and the dose is increased if the estimated DLT is lower than 0.17. Dose assignment will progress with successful completion of two participants at each dose level until DLT occurs. Dose assignment after the first DLT will be made in collaboration with the study statistician for each patient. For Part 1, up to 20 patients will be assigned using the algorithm above. The MTD will be estimated when either the highest dose is reached with no DLTs or after 20 patients have completed the algorithm above. Part 2: After the MTD has been estimated, 10 new patients will be assigned to the "expanded MTD cohort" to estimate PK parameters for irinotecan and SN-38 (active metabolite of irinotecan) with and without curcumin. . The "expanded MTD cohort" might have more than 10 patients if Part 1 sample size is smaller than 20, as long as the total number of patients in the trial does not exceed 30. The estimated MTD might be re-evaluated if the estimated DLT rate at that dose is outside \[0.17, 0.33\].