Capecitabine (Xeloda): from the laboratory to the patient's home

The effective combination therapies with irinotecan for colorectal cancer

Colorectal cancer is the third most common type of cancer worldwide and has become one of the major human disease burdens. In clinical practice, the treatment of colorectal cancer has been closely related to the use of irinotecan. Irinotecan combines with many other anticancer drugs and has a broader range of drug combinations. Combination therapy is one of the most important means of improving anti-tumor efficacy and overcoming drug resistance. Reasonable combination therapy can lead to better patient treatment options, and inappropriate combination therapy will increase patient risk. For the colorectal therapeutic field, the significance of combination therapy is to improve the efficacy, reduce the adverse effects, and improve the ease of treatment. Therefore, we explored the clinical advantages of its combination therapy based on mechanism or metabolism and reviewed the rationale basis and its limitations in conducting exploratory clinical trials on irinotecan combination therapy, including the results of clinical trials on the combination potentiation of cytotoxic drugs, targeted agents, and herbal medicine. We hope that these can evoke more efforts to conduct irinotecan in the laboratory for further studies and evaluations, as well as the possibility of more in-depth development in future clinical trials.

Identification of novel germline polymorphisms governing capecitabine sensitivity

BACKGROUND

Capecitabine, an oral 5-fluorouracil (5-FU) prodrug, is widely used in the treatment of breast, colorectal, and gastric cancers. To guide the selection of patients with potentially the greatest benefit of experiencing antitumor efficacy, or, alternatively, of developing toxicities, identifying genomic predictors of capecitabine sensitivity could permit its more informed use.

METHODS

The objective of this study was to perform capecitabine sensitivity genome-wide association studies (GWAS) using 503 well genotyped human cell lines from individuals representing multiple different world populations. A meta-analysis that included all ethnic populations then enabled the identification of novel germline determinants (single nucleotide polymorphisms [SNPs]) of capecitabine susceptibility.

RESULTS

First, an intrapopulation GWAS of Caucasian individuals identified reference SNP 4702484 (rs4702484) (within adenylate cyclase 2 [ADCY2]) at a level reaching genome-wide significance (P = 5.2 × 10(-8) ). This SNP is located upstream of the 5 methyltetrahydrofolate-homocysteine methyltransferase reductase (MTRR) gene, and it is known that the enzyme for MTRR is involved in the methionine-folate biosynthesis and metabolism pathway, which is the primary target of 5-FU-related compounds, although the authors were unable to identify a direct relation between rs4702484 and MTRR expression in a tested subset of cells. In the meta-analysis, 4 SNPs comprised the top hits, which, again, included rs4702484 and 3 additional SNPs (rs8101143, rs576523, and rs361433) that approached genome-wide significance (P values from 1.9 × 10(-7) to 8.8 × 10(-7) ). The meta-analysis also identified 1 missense variant (rs11722476; serine to asparagine) within switch/sucrose nonfermentable-related, matrix-associated, actin-dependent regulator of chromatin (SMARCAD1), a novel gene for association with capecitabine/5-FU susceptibility.

CONCLUSIONS

Toward the goal of individualizing cancer chemotherapy, the current study identified novel SNPs and genes associated with capecitabine sensitivity that are potentially informative and testable in any patient regardless of ethnicity.

Weekday on-weekend off oral capecitabine: a phase I study of a continuous schedule better simulating protracted fluoropyrimidine therapy

BACKGROUND

Although protracted intravenous 5-fluorouracil is superior to bolus regimens in terms of tumour exposure to the drug during DNA synthesis as well as activity and safety, the oral fluoropyrimidine capecitabine is administered intermittently. In this phase I study, we investigated an alternative, dose-intense continuous regimen.

MATERIALS AND METHODS

Oral capecitabine was administered twice daily continuously with weekend breaks, in patients with advanced solid tumours refractory to standard therapy. Dose escalation proceeded from 1,331 to 2,510 mg/m(2) daily. Dose limiting toxicity (DLT) consisted of any grade-3 or 4 adverse event except for alopecia and skin toxicity resolving within 7 days.

RESULTS

Twenty-five heavily pretreated patients participated in the study. No DLT occurred in the first four cohorts. Two out of four patients developed grade III diarrhoea in the fourth week of capecitabine at 2,510 mg/m(2) (DLT). The most common toxic episodes during all cycles of treatment were grade 1-2 fatigue, skin erythema, abdominal cramps, nausea, constipation and neutropenia. Disease regression was seen in three and stabilisation with clinical benefit in ten patients (clinical benefit response 54%). Pharmacokinetic studies of capecitabine and metabolites in four patients at 2,250 mg/m(2 )daily showed rapid absorption, short plasma half-lives with the exception of FBAL and absence of accumulation or conversion saturation during the course of therapy. At this dose, administered dose intensity in eight patients was 99.3% of the planned one.

CONCLUSIONS

Weekday on-weekend off capecitabine maximizes cytotoxic impact on tumour cells during S-phase by safely simulating protracted fluoropyrimidine therapy at a recommended dose (2,250 mg/m(2)) close to that of the intermittent schedule and clearly higher than the continuous one of 1,331 mg/m(2).

A new classification system of anticancer drugs - based on cell biological mechanisms

The arrival of a great number of new anticancer agents has made it necessary to reclassify all of them. We established a new classification system based on cell biological mechanisms. Anticancer drugs were grouped as cytotoxic drug and modifier, which could regulate the interaction of tumor, host and drugs. The modifiers were subdivided into three groups: cell biological modifier which reverses the abnormal biological behaviour of tumor cells, biological response modifier which regulates the host response of tumor and biochemical modulator which affects the host's metabolic pathway of cytotoxic drug to enhance the chemosensitivity or reduce the adverse reaction. Combination with cell biological modifiers and cytotoxic drugs play a double role of killer and rectifier for tumor cells, whereas biological response modifiers and cytotoxic drugs are combined to regulate the tumor-host interaction. Biochemical modulators and cytotoxic drugs are combined to enhance the chemosensitivity or improve the dose of cytotoxic drugs.