Raltitrexed-induced hepatotoxicity: multivariate analysis of predictive factors

Molecular docking to Toxoplasma gondii thymidylate synthase-dihydrofolate reductase and efficacy of raltitrexed in infected mice

Toxoplasmosis is a zoonosis of worldwide distribution. Currently, two drugs, pyrimethamine and sulfadiazine, are used as a reference in the treatment of toxoplasmosis, but the resistance of Toxoplasma gondii appears as a relevant public health problem. In order to identify new drugs to toxoplasmosis treatment, we performed a molecular docking of raltitrexed to T. gondii thymidylate synthase-dihydrofolate reductase (TS-DHFR) and also evaluated its efficacy in infected mice. Initially, raltitrexed was docked on the crystallographic structures of TS-DHFR from T. gondii and Mus musculus. Then, 48 h after infection with the T. gondii RH strain, different groups of mice received an oral dose of raltitrexed (0.15, 0.75, and 1.5 mg kg^-1). Two days after treatments, raltitrexed was able to prevent mortality and reduce the number of tachyzoites in the peritoneal fluid and liver imprints from infected mice. The results showed that raltitrexed has important protective activities against the T. gondii RH strain. Molecular docking still suggests that the effects against the parasite may be dependent on the inhibition of T. gondii thymidylate synthase. This study opens new perspectives for the use of raltitrexed in patients infected with T. gondii, especially when conventional treatments do not exhibit the expected efficacy.

Raltitrexed-based chemotherapy for advanced colorectal cancer

AIMS

To evaluate the efficiency and safety profile of raltitrexed-based chemotherapy in the treatment of advanced colorectal cancer.

METHODS

An electronic search was undertaken to identify randomized controlled trials comparing raltitrexed-based regimen to 5-fluorouracil-based regimen in patients with advanced colorectal cancer. The outcomes included overall survival, overall response rate and toxicities.

RESULTS

This meta-analysis included 11 studies with 4622 patients. Overall, there were no significant differences between the two regimens in terms of overall survival (HR=1.06, 95% CI: 0.96-1.17, P=0.23) or overall response rate (RR=1.09, 95% CI: 0.86-1.38, P=0.47). In subgroup analysis, patients in raltitrexed/oxaliplatin group had significantly higher partial response (RR=1.53, 95% CI: 1.17-2.00, P=0.002), overall response rate (RR=1.42, 95% CI: 1.10-1.82, P=0.006), disease control rate (RR=1.16, 95% CI: 1.04-1.29, P=0.009) and lower progressive disease (RR=0.61, 95% CI: 0.45-0.84, P=0.002) when compared to 5-fluorouracil/leucovorin/oxaliplatin group. Occurrence of severe anemia (RR=2.23, 95% CI: 1.38-3.59, P=0.0001), asthenia (RR=2.29, 95% CI: 1.36-3.84, P=0.002), hepatic disorders (RR=7.51, 95% CI: 1.30-43.56, P=0.02), and nausea/vomit (RR=1.70, 95% CI: 1.03-2.81, P=0.04) were significantly higher with the raltitrexed arm treatment, while frequencies of grade 3/4 alopecia (RR=0.36, 95% CI: 0.26-0.50, P<0.00001) and stomatitis/mucositis (RR=0.14, 95% CI: 0.07-0.31, P<0.00001) were increased in the 5-fluorouracil group.

CONCLUSIONS

Raltitrexed-based chemotherapy regimen leads to an equivalent overall survival and response rates with acceptable toxicities compared to traditional 5-fluorouracil-based regimen in patients with advanced colorectal cancer. Raltitrexed can be a treatment option for these patients when 5-fluorouracil-based regimens are not tolerated or inappropriate.

Design of the anti-tuberculosis drugs induced adverse reactions in China National Tuberculosis Prevention and Control Scheme Study (ADACS)

BACKGROUND

More than 1 million tuberculosis (TB) patients are receiving the standard anti-TB treatment provided by China National Tuberculosis Prevention and Control Scheme (CNTS) in China every year. Adverse reactions (ADRs) induced by anti-TB drugs could both do harm to patients and lead to anti-TB treatment failure. The ADACS aimed to explore ADRs' incidences, prognoses, economical and public health impacts for TB patients and TB control, and build a DNA bank of TB patients.

METHODS/DESIGN

Multiple study designs were adopted. Firstly, a prospective cohort with 4488 sputum smears positive pulmonary tuberculosis patients was established. Patients were followed up for 6-9 months in 52 counties of four regions. Those suspected ADRs should be checked and confirmed by Chinese State Food and Drug Administration (SFDA). Secondly, if the suspected ADR was anti-TB drug induced liver injury (ATLI), a nested case-control study would be performed which comprised choosing a matched control and doing a plus questionnaire inquiry. Thirdly, health economical data of ADRs would be collected to analyze financial burdens brought by ADRs and cost-effectiveness of ADRs' treatments. Fourthly, a drop of intravenous blood for each patient was taken and saved in FTA card for DNA banking and genotyping. Finally, the demographic, clinical, environmental, administrative and genetic data would be merged for the comprehensive analysis.

DISCUSSION

ADACS will give an overview of anti-TB drugs induced ADRs' incidences, risk factors, treatments, prognoses, and clinical, economical and public health impacts for TB patients applying CNTS regimen in China, and provide suggestions for individualized health care and TB control policy.

Cancer chemotherapy I: hepatocellular injury

Although hepatotoxicity is a frequent concern with all medications, chemotherapeutic agents are more often implicated in causing liver damage than most other drug classes. In many instances, these reactions are considered dose related because cytotoxic therapy directed at rapidly growing cancer cells may readily impact hepatocytes even though they are dividing more slowly. Because the stakes (remission of cancer) are high, so are the risks that the oncologist and the patient are willing to assume. The dose of many chemotherapeutic agents is limited by the toxic effects on the lungs, bone marrow, kidneys, and gastrointestinal system, including the liver. An awareness of the toxic potential of each chemotherapeutic agent is necessary before initiation of new oncologic treatments.

An official ATS statement: hepatotoxicity of antituberculosis therapy

Drug-induced liver injury (DILI) is a problem of increasing significance, but has been a long-standing concern in the treatment of tuberculosis (TB) infection. The liver has a central role in drug metabolism and detoxification, and is consequently vulnerable to injury. The pathogenesis and types of DILI are presented, ranging from hepatic adaptation to hepatocellular injury. Knowledge of the metabolism of anti-TB medications and of the mechanisms of TB DILI is incomplete. Understanding of TB DILI has been hampered by differences in study populations, definitions of hepatotoxicity, and monitoring and reporting practices. Available data regarding the incidence and severity of TB DILI overall, in selected demographic groups, and in those coinfected with HIV or hepatitis B or C virus are presented. Systematic steps for prevention and management of TB DILI are recommended. These include patient and regimen selection to optimize benefits over risks, effective staff and patient education, ready access to care for patients, good communication among providers, and judicious use of clinical and biochemical monitoring. During treatment of latent TB infection (LTBI) alanine aminotransferase (ALT) monitoring is recommended for those who chronically consume alcohol, take concomitant hepatotoxic drugs, have viral hepatitis or other preexisting liver disease or abnormal baseline ALT, have experienced prior isoniazid hepatitis, are pregnant or are within 3 months postpartum. During treatment of TB disease, in addition to these individuals, patients with HIV infection should have ALT monitoring. Some experts recommend biochemical monitoring for those older than 35 years. Treatment should be interrupted and, generally, a modified or alternative regimen used for those with ALT elevation more than three times the upper limit of normal (ULN) in the presence of hepatitis symptoms and/or jaundice, or five times the ULN in the absence of symptoms. Priorities for future studies to develop safer treatments for LTBI and for TB disease are presented.

Uridine diphosphate glucuronosyl transferase 1A1 promoter polymorphism predicts the risk of gastrointestinal toxicity and fatigue induced by irinotecan-based chemotherapy

BACKGROUND

In the current Phase II study, the authors evaluated the association between genomic polymorphic variants in uridine diphosphate glucuronosyl transferase (UGT1A1), methylenetetrahydrofolate reductase (MTHFR), and thymidylate synthase (TS) genes, and the incidence of the adverse effects of irinotecan and raltitrexed in previously heavily treated patients with metastatic colorectal carcinoma.

METHODS

Fifty-six patients received irinotecan (at a dose of 80 mg/m(2) on Days 1, 8, 15, and 22 every 5 wks), combined with raltitrexed (at a dose of 3 mg/m(2) every 3 wks). Genotyping for the MTHFR C677T polymorphism, the TATA box region in the UGT1A1 promoter, and tandem repeats in the TS promoter was performed on genomic DNA extracted from blood. Nineteen variables related to patient, disease, and treatment characteristics, together with genotypes, were analyzed using a binary logistic regression model with stepwise selection to evaluate their correlation with adverse reactions.

RESULTS

Toxicities (determined according to the National Cancer Institute Common Toxicity Criteria) were evaluated in 169 cycles. Grade 3/4 neutropenia was reported to occur in 2% of cycles, Grade 2-4 nausea was reported to occur in 19% of cycles, Grade 2-4 emesis was reported to occur in 9% of cycles, Grade 2-4 diarrhea was reported to occur in 20% of cycles, Grade 2/3 fatigue was reported to occur in 11% of cycles, and Grade 3/4 hepatic toxicity was reported to occur in 7% of cycles. Homozygosis for six TA repeats in the promoter region of the UGT1A1 gene was found to be the main predictive factor for diarrhea (P < 0.00005), emesis (P = 0.0001), and fatigue (P = 0.007). Homozygosis for two tandem repeats in the TS promoter was found to be predictive of a reduced incidence of fatigue (P = 0.044). MTHFR C677T polymorphism was not found to be associated with any adverse reaction.

CONCLUSIONS

In the current study, UGT1A1 promoter polymorphism was found to be predictive of the risk of diarrhea, emesis, and fatigue caused by chemotherapy with irinotecan and raltitrexed. Screening for UGT1A1 promoter polymorphism may be clinically useful for identifying patients at a higher risk of developing a severe or potentially life-threatening toxicity after irinotecan-based chemotherapy.

Phase I Trial and Pharmacokinetic Study of Raltitrexed in Children with Recurrent or Refractory Leukemia: A Pediatric Oncology Group Study

PURPOSE

To evaluate the toxicity, antileukemic activity, and pharmacology of raltitrexed administered weekly for 3 weeks to patients with refractory or recurrent leukemia.

EXPERIMENTAL DESIGN

Raltitrexed was administered as a 15-minute infusion for 3 consecutive weeks every 5 weeks, at doses ranging from 1.3 to 2.8 mg/m(2). The first course was used to determine the dose-limiting toxicities and maximum tolerated dose. Correlative studies included an assessment of raltitrexed pharmacokinetics and measurement of plasma 2'-deoxyuridine concentrations, a surrogate measure of thymidylate synthase inhibition.

RESULTS

Twenty-one children (18 evaluable) with refractory leukemia received 25 courses of raltitrexed. The dose-limiting toxicity was reversible elevation in liver transaminases at the 2.8-mg/m(2) dose level and the maximum tolerated dose was 2.1 mg/m(2) per dose. Pharmacokinetics were best characterized by a two-compartment model with a clearance of 139 mL/min/m(2) (8.3 L/h/m(2)), a 2.4-L volume of distribution, an initial half-life (t(1/2alpha)) of 6 minutes, and a terminal half-life (t(1/2beta)) of 45 minutes. There were three objective responses.

CONCLUSIONS

Raltitrexed was well tolerated when administered as a single agent to children with recurrent or refractory leukemia. We observed preliminary evidence of antileukemia activity using this weekly dosing schedule and these observations support further evaluation of raltitrexed in this population.