Correlation between pharmacokinetic parameters of 5-fluorouracil and related metabolites and adverse reactions in East-Asian patients with advanced colorectal cancer

A Rodent Model of Human-Dose-Equivalent 5-Fluorouracil: Toxicity in the Liver, Kidneys, and Lungs

5-Fluorouracil (5-FU) is a chemotherapy drug widely used to treat a range of cancer types, despite the recurrence of adverse reactions. Therefore, information on its side effects when administered at a clinically recommended dose is relevant. On this basis, we examined the effects of the 5-FU clinical treatment on the integrity of the liver, kidneys, and lungs of rats. For this purpose, 14 male Wistar rats were divided into treated and control groups and 5-FU was administered at 15 mg/kg (4 consecutive days), 6 mg/kg (4 alternate days), and 15 mg/kg on the 14th day. On the 15th day, blood, liver, kidney, and lung samples were collected for histological, oxidative stress, and inflammatory evaluations. We observed a reduction in the antioxidant markers and an increase in lipid hydroperoxides (LOOH) in the liver of treated animals. We also detected elevated levels of inflammatory markers, histological lesions, apoptotic cells, and aspartate aminotransferase. Clinical treatment with 5-FU did not promote inflammatory or oxidative alterations in the kidney samples; however, histological and biochemical changes were observed, including increased serum urea and uric acid. 5-FU reduces endogenous antioxidant defenses and increases LOOH levels in the lungs, suggesting oxidative stress. Inflammation and histopathological alterations were also detected. The clinical protocol of 5-FU promotes toxicity in the liver, kidneys, and lungs of healthy rats, resulting in different levels of histological and biochemical alterations. These results will be useful in the search for new adjuvants to attenuate the adverse effects of 5-FU in such organs.

Paclitaxel exposure-toxicity analysis reveals a pharmacokinetic determinant for dose-limiting neutropenia in East-Asian solid tumor patients: results from two prospective, phase II studies

PURPOSE

The time of a paclitaxel (PTX) concentration remains above 0.05 μM (Tc > 0.05) has been associated with PTX-induced adverse effects in Caucasians, while limited studies were reported in Asians. This study was aimed to explore the characteristics of Tc > 0.05 and the relationship between PTX exposure and toxicity in East-Asian patients.

METHODS

This study was based on two prospective phase II clinical trials and patients with advanced nasopharyngeal cancer (NPC) and non-small cell lung cancer (NSCLC) who were naïve to PTX were included independently. Eligible patients receive PTX (175 mg/m²) and carboplatin (AUC = 5) treatment every 3 weeks. PTX pharmacokinetic analysis was accessed. The relationship between PTX exposure and toxicities after first cycle as well as clinical efficacy was evaluated.

RESULTS

A total of 93 NPC and 40 NSCLC patients were enrolled. PTX exposure was consistent in two trials with average Tc > 0.05 duration of 38.8 h and 38.4 h, respectively. Average Tc > 0.05 in patients with grade 3/4 neutropenia was significantly higher than those without severe neutropenia in NPC patients (P = 0.003) and NSCLC patients (P = 0.007). Cut-off value of Tc > 0.05 were identified from the NPC cohort and then verified in the NSCLC cohort, dividing patients into high exposure Tc > 0.05 group (> 39 h) and low exposure group (≤ 39 h). Incidence of grade 3/4 neutropenia were significantly higher in the high exposure group in NPC cohort (43.3% vs 10.0%, P < 0.001) and NSCLC cohort (42.1% vs 9.5%, P = 0.028). No significant relationship between Tc > 0.05 and efficacy were observed.

CONCLUSION

Patients with PTX Tc > 0.05 duration above 39 h experience more severe neutropenia than those under 39 h. Prospective studies are needed to verify this threshold.