The effect of thalidomide on the pharmacokinetics of irinotecan and metabolites in advanced solid tumor patients

Individualization of Irinotecan Treatment: A Review of Pharmacokinetics, Pharmacodynamics, and Pharmacogenetics

Since its clinical introduction in 1998, the topoisomerase I inhibitor irinotecan has been widely used in the treatment of solid tumors, including colorectal, pancreatic, and lung cancer. Irinotecan therapy is characterized by several dose-limiting toxicities and large interindividual pharmacokinetic variability. Irinotecan has a highly complex metabolism, including hydrolyzation by carboxylesterases to its active metabolite SN-38, which is 100- to 1000-fold more active compared with irinotecan itself. Several phase I and II enzymes, including cytochrome P450 (CYP) 3A4 and uridine diphosphate glucuronosyltransferase (UGT) 1A, are involved in the formation of inactive metabolites, making its metabolism prone to environmental and genetic influences. Genetic variants in the DNA of these enzymes and transporters could predict a part of the drug-related toxicity and efficacy of treatment, which has been shown in retrospective and prospective trials and meta-analyses. Patient characteristics, lifestyle and comedication also influence irinotecan pharmacokinetics. Other factors, including dietary restriction, are currently being studied. Meanwhile, a more tailored approach to prevent excessive toxicity and optimize efficacy is warranted. This review provides an updated overview on today’s literature on irinotecan pharmacokinetics, pharmacodynamics, and pharmacogenetics.

Thalidomide plus chemotherapy exhibit enhanced efficacy in the clinical treatment of T-cell non-Hodgkin's lymphoma: A prospective study of 46 cases

The treatment of T-cell non-Hodgkin's lymphoma (T-NHL) remains challenging. There is currently no standard regimen for the treatment of T-NHL in the first- or second-line setting. Thalidomide was previously shown to exert antitumor effects through inhibiting angiogenesis, promoting apoptosis and immunomodulatory activity. However, all the previous studies on the treatment of lymphoma with thalidomide included patient samples of limited size. In the present study, 46 cases of eligible T-NHL patients were randomized into i) the control group (conventional combined chemotherapy, n=22) and ii) the thalidomide group (thalidomide plus combined chemotherapy, n=24). The median dose of thalidomide was 200 mg (range, 150-400 mg) every night, without reported severe side effects. The clinical response to treatment was as follows: Complete response (CR) in 12 cases, partial response (PR) in 7, stable disease (SD) in 1 and progressive disease (PD) in 4 cases in the thalidomide group; and CR in 8 cases, PR in 6, SD in 3 and PD in 5 cases in the control group. The CR rate was 50.0 and 36.4% in the thalidomide and the control groups, respectively (P<0.05). The median progression-free and overall survival were 12 and undefined months, respectively, in the thalidomide group and 6 and 17 months, respectively, in the control group. The toxicity profile was considered acceptable in both groups. Our results indicated that thalidomide plus combined chemotherapy may exhibit enhanced efficacy in the clinical treatment of T-NHL. In addition, this type of treatment may reduce the frequency of adverse gastrointestinal reactions and help alleviate fear of chemotherapy. Therefore, thalidomide plus combined chemotherapy may be a viable option for the clinical treatment of T-NHL.

Therapeutic targeting of CPT-11 induced diarrhea: a case for prophylaxis

CPT-11 (irinotecan), a DNA topoisomerase I inhibitor is one of the main treatments for colorectal cancer. The main dose limiting toxicities are neutropenia and late onset diarrhea. Though neutropenia is manageable, CPT-11 induced diarrhea is frequently severe, resulting in hospitalizations, dose reductions or omissions leading to ineffective treatment administration. Many potential agents have been tested in preclinical and clinical studies to prevent or ameliorate CPT-11 induced late onset diarrhea. It is predicted that prophylaxis of CPT-11 induced diarrhea will reduce sub-therapeutic dosing as well as hospitalizations and will eventually lead to dose escalations resulting in better response rates. This article reviews various experimental agents and strategies employed to prevent this debilitating toxicity. Covered topics include schedule/dose modification, intestinal alkalization, structural/chemical modification, genetic testing, anti-diarrheal therapies, transporter (ABCB1, ABCC2, BCRP2) inhibitors, enzyme (β-glucuronidase, UGT1A1, CYP3A4, carboxylesterase, COX-2) inducers and inhibitors, probiotics, antibiotics, adsorbing agents, cytokine and growth factor activators and inhibitors and other miscellaneous agents.