Chronomodulated oxaliplatin plus Capecitabine (XELOX) as a first line chemotherapy in metastatic colorectal cancer: A Phase II Brunch regimen study

Diurnal Changes in Capecitabine Clock-Controlled Metabolism Enzymes Are Responsible for Its Pharmacokinetics in Male Mice

The circadian timing system controls absorption, distribution, metabolism, and elimination processes of drug pharmacokinetics over a 24-h period. Exposure of target tissues to the active form of the drug and cytotoxicity display variations depending on the chronopharmacokinetics. For anticancer drugs with narrow therapeutic ranges and dose-limiting side effects, it is particularly important to know the temporal changes in pharmacokinetics. A previous study indicated that pharmacokinetic profile of capecitabine was different depending on dosing time in rat. However, it is not known how such difference is attributed with respect to diurnal rhythm. Therefore, in this study, we evaluated capecitabine-metabolizing enzymes in a diurnal rhythm-dependent manner. To this end, C57BL/6J male mice were orally treated with 500 mg/kg capecitabine at ZT1, ZT7, ZT13, or ZT19. We then determined pharmacokinetics of capecitabine and its metabolites, 5'-deoxy-5-fluorocytidine (5'DFCR), 5'-deoxy-5-fluorouridine (5'DFUR), 5-fluorouracil (5-FU), in plasma and liver. Results revealed that plasma C_max and AUC_0-6h (area under the plasma concentration-time curve from 0 to 6 h) values of capecitabine, 5'DFUR, and 5-FU were higher during the rest phase (ZT1 and ZT7) than the activity phase (ZT13 and ZT19) (p < 0.05). Similarly, C_max and AUC_0-6h values of 5'DFUR and 5-FU in liver were higher during the rest phase than activity phase (p < 0.05), while there was no significant difference in liver concentrations of capecitabine and 5'DFCR. We determined the level of the enzymes responsible for the conversion of capecitabine and its metabolites at each ZT. Results indicated the levels of carboxylesterase 1 and 2, cytidine deaminase, uridine phosphorylase 2, and dihydropyrimidine dehydrogenase (p < 0.05) are being rhythmically regulated and, in turn, attributed different pharmacokinetics profiles of capecitabine and its metabolism. This study highlights the importance of capecitabine administration time to increase the efficacy with minimum adverse effects.

Exploring the link between chronobiology and drug delivery: effects on cancer therapy

Circadian clock is an impressive timing system responsible for the control of several metabolic, physiological and behavioural processes. Nowadays, the connection between the circadian clock and cancer occurrence and development is consensual. Therefore, the inclusion of circadian timing into cancer therapy may potentially offer a more effective and less toxic approach. This way, chronotherapy has been shown to improve cancer treatment efficacy. Despite this relevant finding, its clinical application is poorly exploited. The conception of novel anticancer drug delivery systems and the combination of chronobiology with nanotechnology may provide a powerful tool to optimize cancer therapy, instigating the incorporation of the circadian timing into clinical practice towards a more personalized drug delivery. This review focuses on the recent advances in the field of cancer chronobiology, on the link between cancer and the disruption of circadian rhythms and on the promising targeted drug nanodelivery approaches aiming the clinical application of cancer chronotherapy.

Assessment of pharmacokinetic variations of capecitabine after multiple administration in rats: a physiologically based pharmacokinetic model

PURPOSE

Capecitabine is a prodrug of 5-fluorouracil (5-FU) used for the treatment of colorectal cancer, with a two-week course of administration. However, the variance in plasma concentration and metabolic enzyme activities after multiple administration of capecitabine and its metabolites is unknown. The aim of this study was to identify the variance and predict the plasma concentration profile of capecitabine and its metabolites, using metabolic enzyme activities, to develop a more effective and safer medication.

METHODS

Rats orally received 180 mg/kg of capecitabine once a day for two weeks. Blood samples were collected nine times, and plasma concentration was measured on day 1, 7, and 14. The liver and small intestine were removed after blood sampling and were used in vitro to evaluate metabolic enzyme activities of carboxylesterase, cytidine deaminase, and thymidine phosphorylase. A physiologically based pharmacokinetic (PBPK) model was developed using in vitro results.

RESULTS

Area under the plasma concentration-time curve from 0 h to infinity of 5-FU on day 7 and day 14 was significantly lower than that on day 1. Intrinsic clearance of thymidine phosphorylase in the liver on day 7 and day 14 was 1.4 and 1.3 times lower than that on day 1, respectively. The PBPK model described the observed plasma concentration of capecitabine and its metabolites.

CONCLUSION

The decreased plasma concentration of capecitabine was caused by decreased metabolic enzyme activity. Efficacy can be improved by dose adjustment of capecitabine based on metabolic enzyme activities, using the PBPK model.

Circadian variations in the pharmacokinetics of the oral anticancer agent tegafur-uracil (UFT) and its metabolites in rats

Uracil-tegafur (UFT) is an oral anticancer drug containing uracil and 5‑fluorouracil prodrug tegafur and is widely used for adjuvant chemotherapy of colorectal cancer. Although clinical data show circadian variations in plasma 5‑fluorouracil concentrations during its long-term infusion, and feasibility studies of chronomodulated administration have been previously reported, the circadian pattern in plasma 5‑fluorouracil concentration after UFT administrations remains unclear. The aim of this study was to identify factors causing circadian variations in UFT pharmacokinetics and estimate circadian patterns of plasma 5‑fluorouracil concentration corresponding to UFT dosing time in rats. Rats were orally administered UFT (15 mg/kg as tegafur) at three different times of the day: 07:00 (23 h after light onset, HALO), 13:00 (5 HALO), or 19:00 (11 HALO), and then plasma concentrations of tegafur, 5‑fluorouracil, and uracil were measured after UFT administration. We found that the area under the plasma concentration-time curves (AUC_0-∞) of 5‑fluorouracil depended on the UFT dosing time of day with a 2.4-fold difference between the peak (at 19:00: 13.7 ± 1.4 μmol·h/L) and trough (at 13:00: 5.6 ± 1.3 μmol·h/L). The simulated population mean clearance of 5‑fluorouracil followed a 24-h cosine circadian curve, with the highest value in the early light phase being 2.2-fold higher than the lowest value in the early dark phase, which was an inverse circadian pattern compared to the plasma 5‑fluorouracil concentration. The plasma tegafur levels suggested that circadian variation in tegafur absorption and conversion to 5‑fluorouracil are factors causing variations in plasma 5‑fluorouracil levels following UFT administration. In conclusion, the circadian pattern of 5‑fluorouracil clearance and circadian variations in tegafur pharmacokinetics are important determinants of plasma 5‑fluorouracil concentrations following UFT administration. This knowledge could help in developing a chronomodulated administration strategy of UFT for improving clinical outcomes.

Genetic polymorphisms in cyclin H gene are associated with oxaliplatin-induced acute peripheral neuropathy in South Indian digestive tract cancer patients

PURPOSE

Digestive tract cancer patients treated with oxaliplatin are often associated with the development of peripheral neuropathy. The aim of the present study is to identify the influence of single-nucleotide polymorphisms (SNPs) in genes involved in oxaliplatin metabolism, cell cycle control, detoxification or excretion pathways with the development of oxaliplatin-induced acute peripheral neuropathy (acute OXAIPN) and its severity among digestive tract cancer patients treated with oxaliplatin-based chemotherapy.

PATIENTS AND METHODS

A total of 228 digestive tract cancer patients undergoing with the oxaliplatin-based chemotherapy between November 2014 and December 2016 were included in the current study. Genomic DNA was extracted from peripheral blood by standard phenol-chloroform method. Genotyping of five SNPs in four genes [GSTP₁ (rs1965), ABCG2 (rs3114018), CCNH (rs2230641, rs3093816), AGXT (rs4426527)] was carried out by Real-Time TaqMan SNP genotyping assay.

RESULTS

We found that the two genetic variants rs2230641 and rs3093816 in cyclin H (CCNH) gene were significantly associated with both the incidence and severity of acute OXAIPN. For CCNH-rs2230641 (AA vs AG+GG; dominant model) Incidence: OR 2.62, 95% CI 1.44-4.75, p = 0.001, severity; OR 4.64, 95% CI 1.58-13.62, p = 0.002. For CCNH-rs3093816 (AA vs AG+GG; dominant model); incidence: OR 3.43, 95% CI 1.57-7.50, p = 0.001; severity: OR 2.36, 95% CI 1.05-5.30, p = 0.033.

CONCLUSIONS

The results of the present study found significant association between CCNH polymorphisms and acute OXAIPN development. However, further studies are warranted from independent groups to validate our study results.

Circadian variations in the pharmacokinetics of capecitabine and its metabolites in rats

Capecitabine, an orally available prodrug of 5-fluorouracil, is widely used to treat patients with colorectal cancer. Although various studies have shown circadian variations in plasma 5-fluorouracil concentrations during long-term infusion, it is still unknown whether circadian variations also exist following administration of capecitabine. The present study aimed to investigate whether the pharmacokinetics of capecitabine and its metabolites, including 5-fluorouracil, vary according to administration time in rats. Rats were orally administered capecitabine (180mg/kg) at 07:00 (23h after light onset, HALO), 13:00 (5 HALO), or 19:00h (11 HALO). Plasma concentrations of capecitabine and its metabolites, such as 5'-deoxy-5-fluorocytidine (5'-DFCR), 5'-deoxy-5-fluorouridine (5'-DFUR), and 5-fluorouracil, were determined after capecitabine administration. The results showed that the t_1/2 and AUC_0-∞ values of 5-fluorouracil differed as a function of the dosing time of capecitabine. The maximum and minimum mean t_1/2 values of 5-fluorouracil were obtained when the drug was administered at 07:00h (23 HALO: 3.1±1.2h) and 13:00h (5 HALO: 1.5±0.6h), respectively. The AUC_0-∞ value of 5-fluorouracil at 07:00h (23 HALO: 533.9±195.7μmol∙h/L) was 1.8-fold higher than the value at 13:00h (5 HALO: 302.5±157.1μmol∙h/L). The clearance of 5-fluorouracil followed a cosine circadian curve, and the simulated population mean clearance was highest at rest times and lowest during active times in rats. The results for the plasma 5'-DFCR and 5'-DFUR levels indicated that circadian variations in the sequential metabolism of capecitabine to 5-fluorouracil would also affect plasma 5-fluorouracil levels following capecitabine administration. In conclusion, the pharmacokinetics of capecitabine and its metabolites, including 5-fluorouracil, varied according to time of dosing, suggesting that the capecitabine administration time is an important factor in achieving sufficient efficacy and reducing toxicity in patients.

Molecular Aspects of Circadian Pharmacology and Relevance for Cancer Chronotherapy

The circadian timing system (CTS) controls various biological functions in mammals including xenobiotic metabolism and detoxification, immune functions, cell cycle events, apoptosis and angiogenesis. Although the importance of the CTS is well known in the pharmacology of drugs, it is less appreciated at the clinical level. Genome-wide studies highlighted that the majority of drug target genes are controlled by CTS. This suggests that chronotherapeutic approaches should be taken for many drugs to enhance their effectiveness. Currently chronotherapeutic approaches are successfully applied in the treatment of different types of cancers. The chronotherapy approach has improved the tolerability and antitumor efficacy of anticancer drugs both in experimental animals and in cancer patients. Thus, chronobiological studies have been of importance in determining the most appropriate time of administration of anticancer agents to minimize their side effects or toxicity and enhance treatment efficacy, so as to optimize the therapeutic ratio. This review focuses on the underlying mechanisms of the circadian pharmacology i.e., chronopharmacokinetics and chronopharmacodynamics of anticancer agents with the molecular aspects, and provides an overview of chronotherapy in cancer and some of the recent advances in the development of chronopharmaceutics.

Oxaliplatin-induced Peripheral Neuropathy in South Indian Cancer Patients: A Prospective Study in Digestive Tract Cancer Patients

Purpose:

The aim of the current study is to report our prospective experience on the prevalence of oxaliplatin-induced peripheral neuropathy (OXAIPN) in patients with digestive tract cancers treated with oxaliplatin-based combination therapy.

Materials and Methods:

A total of 219 patients scheduled to be treated with oxaliplatin-based combination therapy were prospectively examined at baseline and follow-up during the therapy between November 2014 and December 2016. The incidence of acute OXAIPN was measured using a descriptive questionnaire (yes/no question) based on sum of number of symptoms present and NCI-CTCAE version 4.03 was applied to clinically grade the severity of chronic OXAIPN.

Results:

Acute and chronic OXAIPN was found in 108 of 219 (49.3%) and 127 of 219 (58%) patients, respectively. Out of 11 acute OXAIPN symptoms, the vast majority of patients manifested cold-induced pharyngolaryngeal (63.8%) dysesthesias or perioral (61.1%) paresthesias. Development of acute OXAIPN was predictive of subsequent development of chronic OXAIPN (P = 0.0001). All the patients received a median cumulative dose of 780 mg/m² (range: 130–1040 mg/m²). There was a significant correlation between the patients who received the median cumulative dose and the development of chronic OXAIPN. The incidences of OXAIPN in patients with median cumulative dose of ≤780 mg/m² was 51/120 (42.5%) and >780 mg/m² was OXAIPN 76/99 (76.7%) (P = 0.0001).

Conclusion:

The current study results demonstrate that the vast majority of patients who receive oxaliplatin-based combination chemotherapy will manifest acute OXAIPN that may contribute to the development of chronic peripheral neuropathy on repeated courses of drug administration.