5-fluorouracil Toxicity Research Articles

Review of the fluoropyrimidine antidote uridine triacetate.

In 2015, the United States Food and Drug Administration (FDA) approved uridine triacetate to treat overdose and severe toxicity of the fluoropyrimidine chemotherapy agents 5-fluorouracil (5-FU) and its oral prodrug capecitabine. Uridine triacetate is as an oral prodrug of uridine that competes with cytotoxic fluoropyrimidine metabolites for incorporation into nucleotides. Two million people worldwide start fluoropyrimidine chemotherapy each year, with 20-30% developing severe or life-threatening adverse effects, often attributable to a genetic predisposition such as dihydropyrimidine dehydrogenase deficiency. Whilst genetic prescreening is recommended prior to starting fluoropyrimidine agents, this only prevents 20-30% of early-onset life-threatening toxicity and so does not obviate the need for an antidote. Initial in-human studies established that uridine triacetate more than doubles the maximum tolerated weekly 5-FU bolus dose. A lack of clinical equipoise meant a placebo-controlled phase III trial was not ethical and so the phase III trials used historical controls. These found that uridine triacetate improved survival in those with fluoropyrimidine overdose and severe toxicity from 16% to 94%, with 34% able to resume chemotherapy within 30 days. Five case reports of delayed fluoropyrimidine toxicity demonstrate improvement following uridine triacetate treatment 120-504 h after last fluoropyrimidine administration, suggesting efficacy beyond the FDA licencing indications. Mechanistically uridine triacetate would be expected to be effective for overdose and severe toxicity of tegafur (a 5-FU prodrug), but there are no published case reports describing this. Uridine triacetate is available internationally through an expanded access scheme and has been available in the UK since 2019 on a named patient basis.

Rapid determination of uracil in biological fluids at mercury thin film electrode for early detection of potential 5-fluorouracil toxicity due to dihydropyrimidine dehydrogenase deficiency

Determination of plasma uracil was reported as a method for evaluation of Dihydropyrimidine dehydrogenase (DPD) activity that is highly demanded to ensure the safe administration of 5-fluorouracil (5-FU)-based therapies to cancer patients. This work reports the development of a simple electroanalytical method based on adsorptive stripping square wave voltammetry (AdSWV) at mercury film-coated glassy carbon electrode (MF/GCE) for the highly sensitive determination of uracil in biological fluids that can be used for diagnosis of decreased DPD activity. Due to the formation of the HgII–Uracil complex at the electrode surface, the accuracy of the measurement was not affected by the complicated matrices in biological fluids including human serum, plasma, and urine. The high sensitivity of the developed method results in a low limit of detection (≈1.3 nM) in human plasma samples, falling below the practical cut-off level of 15 ng mL−1 (≈0.14 μM). This threshold concentration is crucial for predicting 5-FU toxicity, as reported in buffer, and ≤1.15% in biological samples), and accuracy (recovery percentage close to 100%).

Hyaluronic acid-conjugated methotrexate and 5-fluorouracil for targeted drug delivery

The delivery of chemotherapeutical drugs via nanomaterials has become a focus of pharmaceutical research over several decades due to improved drug delivery to cancer cells, decreased side effects on normal tissues, and increased therapeutic efficacy. Herein, a novel hyaluronic acid-conjugated methotrexate and 5-fluorouracil nanodrug system has been developed to address the critical limitations associated with the high toxicity and side effects of methotrexate and 5-fluorouracil. Furthermore, this nanodrug system enhances the targeting capacity of drug molecules and facilitates the potential integration of multimodal drug therapies. Concomitantly, the synergistic effects of MTX with 5-fluorouracil have been shown to improve the therapeutic index of MTX while attenuating the associated toxicities of MTX. The structure and micromorphology of the novel nanodrug can be confirmed by 1HNMR, FT-IR, UV–Vis, DLS, TEM, and AFM. Due to the ability of HA to bind to CD44 receptors activated on the surface of cancer cells and its enhanced permeability and retention (EPR) effect, the novel nanodrug we designed and synthesized can effectively target cancer cells. Cell counting Kit-8 (CCK8), flow cytometry, and live-dead staining assays in vitro showed that this nanodrug system had high targeting and antitumor activity against CD44 receptors. By using drugs to act on patient-derived colorectal, liver, and breast cancer organoids, the anticancer effect of the nanodrug was identified and verified. These results showed that the nanodrug system developed in this study may have great potential as a targeted therapy for cancer.

Genotyping of <i>UGT1A1</i> and <i>DPYD</i> polymorphisms in patients with colorectal cancer. A review

The main treatment regimen for patients with metastatic colorectal cancer is still cycle-based chemotherapy with fluoropyridines combined with oxaliplatin and/or irinotecan. The activity of these chemotherapeutic agents depends on a predominant specific metabolism pathway. Therefore, the genetic features of the patient become important as a prognostic factor for the occurrence and severity of adverse events during therapy. The review addresses current views about the mechanisms of toxic activity of irinotecan and fluoropyrimidines, analyzes the results of pharmacogenotyping of UGT1A1 and DPYD polymorphisms, and published studies assessing the relationship between genetic variants of these genes and the safety of chemotherapy. A significant role of the population component is noted both in the distribution of gene allele frequencies and in their phenotypic expression. For some polymorphisms of the DPYD gene, dose-dependent associations with the toxicity of 5-fluorouracil have been established. Nevertheless, they determine only 1–8% of cases out of 40–60% of patients with adverse events and DPD protein deficiency associated with other enzyme activity reduction mechanisms. The pharmacological significance of UGT1A1 genetic variations is associated with toxicity prediction and helps allocate patients for more effective high-dose irinotecan therapy. Data is presented on the pharmacogenotyping of these markers to establish the dose of drugs in various national guidelines. Currently, the heterogeneity of the available pharmacogenetic data leaves open the question of determining the most appropriate dosing strategies for irinotecan and fluoropyrimidines. The widespread introduction of UGT1A1 and DPYD genotyping into clinical practice balances the economic feasibility and predictive value of biomarkers. As pharmacogenomics evolves rapidly, more robust research would overcome existing hurdles and facilitate personalized drug dosage decisions.

S2373 Dihydropyrimidine Dehydrogenase Deficiency Leading to Fluorouracil Toxicity in a Patient With Colorectal Adenocarcinoma

S2373 Dihydropyrimidine Dehydrogenase Deficiency Leading to Fluorouracil Toxicity in a Patient With Colorectal Adenocarcinoma

Discovery of novel tubulin CBSI (R)-9k from the indanone scaffold for the treatment of colorectal cancer.

In view of the serious adverse reactions and clinical toxicity of first line therapy 5-fluorouracil and lack of small molecule therapeutics in colorectal cancer chemotherapy, a series of natural scaffold-based 3-arylindanone derivatives (9a-q) were designed, synthesized and evaluated as tubulin polymerization inhibitors targeting the colchicine site. The most potent colchicine binding site inhibitor (CBSI), (R)-9k, exhibited 14-38 times more dominant anti-proliferative activity against three colon cancer cell lines than 5-fluorouracil. Particularly, (R)-9k showed higher selectivity against human normal cells compared with 5-fluorouracil and colchicine, and displayed negligible cardiotoxicity through hERG assessment. Furthermore, the binding of (R)-9k to the colchicine site was strongly supported by EBI competition assay and (R)-9k inhibited more tubulin polymerization than colchicine. Besides, the mechanism of action and binding modes of (R)-9k were verified by molecular dynamics simulations and docking. Therefore, (R)-9k could be regarded as a promising CBSI for colorectal cancer therapy.

Predicting Dihydropyrimidine Dehydrogenase Deficiency and Related 5-Fluorouracil Toxicity: Opportunities and Challenges of DPYD Exon Sequencing and the Role of Phenotyping Assays.

Deficiency of dihydropyrimidine dehydrogenase (DPD), encoded by the DPYD gene, is associated with severe toxicity induced by the anti-cancer drug 5-Fluorouracil (5-FU). DPYD genotyping of four recommended polymorphisms is widely used to predict toxicity, yet their prediction power is limited. Increasing availability of next generation sequencing (NGS) will allow us to screen rare variants, predicting a larger fraction of DPD deficiencies. Genotype-phenotype correlations were investigated by performing DPYD exon sequencing in 94 patients assessed for DPD deficiency by the 5-FU degradation rate (5-FUDR) assay. Association of common variants with 5-FUDR was analyzed with the SNPStats software. Functional interpretation of rare variants was performed by in-silico analysis (using the HSF system and PredictSNP) and literature review. A total of 23 rare variants and 8 common variants were detected. Among common variants, a significant association was found between homozygosity for the rs72728438 (c.1974+75A>G) and decreased 5-FUDR. Haplotype analysis did not detect significant associations with 5-FUDR. Overall, in our sample cohort, NGS exon sequencing allowed us to explain 42.5% of the total DPD deficiencies. NGS sharply improves prediction of DPD deficiencies, yet a broader collection of genotype-phenotype association data is needed to enable the clinical use of sequencing data.

Impact of Guidelines Regarding Dihydropyrimidine Dehydrogenase (DPD) Deficiency Screening Using Uracil-Based Phenotyping on the Reduction of Severe Side Effect of 5-Fluorouracil-Based Chemotherapy: A Propension Score Analysis.

Dihydropyrimidine dehydrogenase (DPD) deficiency is associated with severe fluoropyrimidines-induced toxicity. As of September 2018, French recommendations call for screening for DPD deficiency by plasma uracil quantification prior to all fluoropyrimidine-based chemotherapy. A dose reduction of fluoropyrimidine is recommended when uracil concentration is equal to or greater than 16 ng/mL. This matched retrospective study assessed the impact of DPD screening on the reduction of severe side effects and on the management of DPD-deficient patients. Using a propensity score, we balanced the factors influencing 5-Fluorouracil (5-FU) toxicity. Then, the severity scores (G3 and G4 severity as well as their frequency) of patients who did not benefit from DPD screening were compared with those of patients who benefited from DPD screening for each treatment cycle (from 1 to 4). Among 349 screened patients, 198 treated patients were included. Among them, 31 (15.7%) had DPD deficiency (median uracilemia 19.8 ng/mL (range: 16.1–172.3)). The median toxicity severity score was higher in the unscreened group for each treatment cycle (0 vs. 1, p < 0.001 at each cycle from 1 to 4) as well as the cumulative score during all courses of treatment (p = 0.028). DPD-deficient patients received a significantly lower dose of 5-FU (p < 0.001). This study suggests that pretherapeutic plasmatic uracil assessment, along with 5-FU dosage adjustment, may be beneficial in reducing 5-FU toxicity in real-life patients.

DPYD and TYMS polymorphisms as predictors of 5 fluorouracil toxicity in colorectal cancer patients

Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer death. 5-Fluorouracil (5-FU) is an essential component of systemic chemotherapy for CRC. Our objective was to determine the genotypic frequency of polymorphisms affecting dihydropyrimidine dehydrogenase (DPYD) and thymidylate synthetase (TYMS) genes and to correlate the genetic profile with the toxicity due to 5-FU, also considering nongenetic factors. This is a prospective study that involved 66 patients. We extracted DNA by salting out methods. We carried out the genotyping of the different polymorphisms by simple PCR for the TYMS 5'UTR and by PCR-RFLP for DPYD: 1905 + 1 G > A, 85 T > C, 496 A > G, 1679 T > G, c.483 + 18G > A and the TYMS: 5'UTR VNTR, 5'UTR G > C and 3'UTR. The study of the association of DPYD and TYMS polymorphisms with the various signs of toxicity under 5-FU revealed that the polymorphisms 496 A > G were significantly associated with hepatotoxicity: OR = 3.85 (p = 0.04). In addition, 85 T > C was significantly associated with mucositis and neurotoxicity: OR = 4.35 (p = 0.03), OR = 3.79 (p = 0.02). For TYMS, the only significant association we observed for 5'UTR with vomiting: OR = 3.34 (p = 0.04). The incidence of adverse reactions related to 5-FU appears to be influenced in patients with CRC by the identified DPYD and TYMS gene polymorphisms in the Tunisian population.

Case report: Uridine triacetate in the management of delayed onset 5-fluorouracil toxicity: A case report and review of literature

5-fluorouracil (5FU) and capecitabine are fluoropyrimidine anti-neoplastic drugs commonly used in the treatment of different types of cancer. Hereditary dihydropyrimdine deaminase (DPD), thymidylate synthase mutations and drug overdose may lead to life-threatening toxicities. Uridine triacetate (UTA) is an emergency treatment for overdoses and early onset, severe or life-threatening toxicities from fluoropyrimidines. It is approved for use in adults and children within 96 h of last fluoropyrimidine administration. We present the case of a 64-year-old male treated with 5-FU and oxaliplatin as adjuvant systemic therapy for stage IIIA rectal cancer who developed delayed central nervous system toxicity 18 days after initiating chemotherapy. He had rapidly worsening encephalopathy and ataxia. Laboratory workups, MRI brain and EEG were negative. He was started on UTA with concerns of 5-FU toxicity due to the life-threatening nature of his condition even beyond the recommended 96-h time cut-off. He had rapid improvement in clinical status and resolution of encephalopathy. DPD deficiency testing later resulted as heterozygous for IVS14+1G>A allele indicating enzyme deficiency. This report demonstrates the importance of identifying delayed side effects with fluoropyrimidine therapy and potential treatment for reversing these effects. We also did an extensive literature review and obtained reports from the uridine triacetate clinical trials on patients receiving UTA after the 96-h cut-off. Based on our experience and previous published reports, a patient developing life-threatening delayed 5-FU toxicity should also be considered for UTA on a case-by-case basis.

Pharmacogenetic Study of the Dihydropyridine Dehydrogenase Gene in Jordanian Patients with Colorectal Cancer.

Several studies have shown an association between 5-fluorouracil toxicity and variations in the dihydropyrimidine dehydrogenase (DPYD) gene. This cross-sectional study aims to elucidate the association between genetic variations in the DPYD gene and 5-fluorouracil toxicity among Jordanians with colorectal cancer (CRC). 80 CRC Patients were recruited to screen for mutations in the DPYD gene using the Sanger sequencing technique. Sequencing results were analyzed using Mutation Surveyor software, and mutational effects were predicted by the Mutation Tester bioinformatics tool. Three reported variants (c.85T>C, c.1740+40A>G, c.1740+39C>T) and one novel (g.97515583_97515584insA) variant were identified in this study. Results showed a significant association between these variants and toxicity to 5-Fluorouracil with P-values 0.002, 0.005, 0.019, 0.017, respectively. However, there was no significant association between variants and cancer free survival. The present study identified several variants in the DPYD gene among Jordanians with colorectal cancer, which are associated with toxicity to 5-Fluorouracil treatment.

Cytotoxic and Apoptotic Effects of the Combination of Borax (Sodium Tetraborate) and 5-Fluorouracil on DLD-1 Human Colorectal Adenocarcinoma Cell Line

Colorectal cancer (CRC) remains a crucial health problem due to the toxicity of 5-Fluorouracil (5-FU) as first-line chemotherapy agent for treating CRC. The anticancer effects of boron and its compounds have been shown in various cell lines. This study aimed to examine the cytotoxic and apoptotic effects of borax (sodium tetraborate) alone or along with 5-FU on human CRC cells, DLD-1. Cytotoxicity and apoptosis were determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay, 4',6-diamidino-2-phenylindole and annexin V/propidium iodide staining. The results showed that combined treatment revealed a significant time- and concentration-dependent cytotoxic effect on DLD-1 cells compared with borax or 5-FU treatment alone. The combination of borax and 5-FU induced a clear increase in the early apoptotic cell percentage, compared to the cells treated with monotherapies. Additionally, a significant increase in condensed and fragmented nuclei was detected in DLD-1 cells treated with the combination treatment compared with borax or 5-FU alone. Our current findings suggest that the combination of borax with 5-FU has a strong cytotoxic and apoptotic effect on the human CRC DLD-1 cells.

Influence of the skeletal muscle index on pharmacokinetics and toxicity of fluorouracil.

The body composition of patients has been associated with tolerability and effectiveness of anticancer therapy. This study aimed to assess the influence of the skeletal muscle index (SMI) on the pharmacokinetics and toxicity of fluorouracil. Patients treated in an oncological practice with fluorouracil-based chemotherapy and undergoing therapeutic drug monitoring were retrospectively investigated. Computed tomography images were analyzed to measure abdominal skeletal muscle areas in Hounsfield units for the psoas major muscle, back and total skeletal muscle to determine the SMI. For the latter, an automated segmentation method was used additionally. SMI measures were tested as covariates on fluorouracil clearance in a population pharmacokinetic model. Furthermore, regression analyses were performed to analyze the influence of SMI measures on the probability of clinically relevant adverse events (CTCAE grades ≥ 2). Fluorouracil plasma concentrations of 111 patients were available. Covariate analyses showed significant improvements of the model fit by all SMI measures. However, interindividual variability of fluorouracil clearance was only slightly reduced, whereas the SMI of the back muscle showed the largest reduction (-1.1 percentage points). Lower SMI values of the back muscle increased the probability for polyneuropathy and lower SMI of the psoas increased the probability for fatigue. Our results suggest that pharmacokinetics and toxicity of fluorouracil may be associated with specific SMI measures which deserve further investigation.

Use of 5-Fluorouracil Injections in Traumatic Cicatricial Malposition of Eyelids.

Scarring in the eyelid and periocular regions has both cosmetic and functional implications. Free and unrestricted movement of the eyelids is imperative for opening and closing of the eye and for protection of the ocular surface. Among the nonsurgical modalities of scar treatment, the antineoplastic drug 5-fluorouracil has been used widely.1 We share our experience with its use in posttraumatic cicatrizing eyelid malposition. All the patients had undergone primary treatment for eyelid trauma elsewhere. The patients presented with lagophthalmos (Fig. 1), ptosis, or cicatricial ectropion. [See Figure, Supplemental Digital Content 1, which shows a patient with ptosis caused by cicatricial tethering of eyelid at the lateral orbital rim. Photograph taken 4 weeks after the injury. Lateral view shows the scar (above) and the resolution of ptosis 4 weeks after the last injection. A total of 105 mg of 5-fluorouracil was injected in three sittings. The patient did not desire surgery. Lateral view after 5-fluorouracil injection shows improvement in the scar (below), https://links.lww.com/PRS/F327.] Twelve patients (mean age, 38.3 years; SD, 12.6 years; nine male and three female) received injections before any surgical intervention at our clinic.Fig. 1.: (Above) Clinical photograph showing cicatricial lagophthalmos 4 weeks after trauma. (Below) Clinical photograph of the patient at 12 months follow-up after injection of 5-fluorouracil (total 140 mg in four sittings).Measurements and clinical photographs were taken before and after injection. We continued the injections every 3 to 4 weeks or until improvement plateaued. The earliest injections were at 4 weeks, with a mean delay of 3.08 months. All cases were performed under topical anesthesia with a mixture of lignocaine 2.5% W/W and prilocaine 2.5% W/W (Prilox cream; Neon Laboratories, Bangalore, India). We injected 5-fluorouracil 50 mg/ml (Fluracil; Zydus Cadila, Ahmedabad, India) with a 26-gauge or 30-gauge needle in 0.1-ml aliquots injected at intervals of 5 mm into and around the scar. Traction sutures were applied to facilitate lengthening of the scar. The mean interval from injury to first presentation at our clinic was 3.08 months (range, 1 to 14 months). The mean dose of injections required was 54.3 mg (range, 15 to 105 mg) in one to four sittings. Objective improvement was seen in 11 of 12 patients (91.6 percent) (Fig. 1). [See Figure, Supplemental Digital Content 1, https://links.lww.com/PRS/F327.] Reconstructive surgery could be avoided in six of 12 patients (50 percent). Patients with anterior lamellar skin deficiency required surgery. Pain and burning sensation were reported after the first injections in the first two patients. Oral paracetamol 650 mg immediately after injection kept the patients comfortable. No patient experienced 5-fluorouracil toxicity on the ocular surface. No patient showed wound dehiscence or skin ulceration, known adverse events.2 5-Fluorouracil, an antimetabolite, acts both on the phase of proliferation and the phase of maturation in the healing wound. It inhibits DNA synthesis and repair.2 It also interferes with RNA function, reduces proliferation of dermal fibroblasts, and affects transforming growth factor–β signaling and formation of type 1 collagen.2,3 Reports also show that the inhibitory effects of 5-fluorouracil on fibroblast proliferation and fibroblast action last for more than 6 weeks after a single application.4 There are few original reports of periocular use of 5-fluorouracil.5 Conventional use has been to inject weekly or biweekly, starting soon after surgery.5 For our series, the drug was injected during the phase of wound maturation, with less frequent dosing. The injections were still effective, with few adverse events. We propose that injection of 5-fluorouracil is a safe and effective modality for wound modulation in eyelid scarring and can reduce the need for surgical intervention. PATIENT CONSENT Patients provided written informed consent for the use of their images. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.

Optimizing the prescription doses and tolerability of systemic therapy in head and neck cancer patients.

Squamous cell carcinoma of the head and neck accounts for 330 000 deaths and 650 000 cases worldwide annually. Systemic therapy is an essential pillar of multimodal therapy despite being accompanied with substantial toxicity. This article reviews the latest advances in systemic therapy for the treatment of locoregionally advanced and reccurent/metastatic head and neck cancer from a tolerability perspective. Multiple recent attempts have been made to optimize tolerability (and efficacy) of systemic therapy utilizing new regimens, modified prescription doses, drugs such as immunotherapies or genotyping to tailor the systemic therapy to the individual patient. Although treatment benefit has to be weighed against potential toxicity, it is reasonable to anticipate potential side effects of systemic therapies. In a vulnerable elderly or Asian patient population upfront dose modifications of cytotoxic chemotherapies might be reasonable. Special attention should be laid on the patient's nutritional status and early intervention recommended. Dihydropyrimidine dehydrogenase genotyping can predict 5-fluorouracil toxicity and identify patients for whom alternative regimens are more suitable. As for immune checkpoint inhibitor therapy, despite being well tolerated, the identification of biomarkers to predict reduced tolerability or severe toxicity would be highly desirable.

Synthesis of 5-fluorouracil-lactoside derivatives and experimental study on their anti-oral squamous cell carcinoma activity.

To reduce the toxicity of 5-fluorouracil (5-FU), design and synthesize 5-FU-lactoside derivatives, and preliminarily study their antitumor activities. Target compounds were prepared with Vorbrüggenglycation procedures, the structures were characterized through high resolution mass spectrometry (HRMS), 1H nuclear magnetic resonance (1HNMR), carbon-13 nuclear magnetic resonance (13CNMR), heteronuclear multiple quantum correlation (HMQC), and heteronuclear multiple bond correlation (HMBC). A cell counting kit (CCK)-8 test was performed to examine their in vitro toxicity and antitumor activity. Experimental data were tested by χ2, and statistically significant differences were denoted by P<0.05. The target compounds were synthesized through a simple and efficient method. 1HNMR, 13CNMR, HMQC, HMBC, and HRMS confirmed that Ⅰa and Ⅰb were 5-FU nucleoside derivatives substituted with lactoside groups at N-1 and N-3, respectively. The CCK-8 test verified that high concentrations (0.7 μmol·mL-1) of Ⅰa and Ⅰb inhibited the growth of normal oral keratinocytes (NOK) by 30.28% and 50.68% after 24 h of treatment. Both values were lower than the inhibitory effect of 5-FU (68.22%; P<0.05). Ⅰb had a significant inhibitory effect on the growth of two oral squamous cell carcinoma cell lines. The inhibition rates of Cal-27 cells and UM SCC-47 cells treated with 0.7 μmol·mL-1 for 24 h were 81.20% and 80.19%, respectively. Ⅰa and Ⅰb are less toxic than 5-FU. The antitumor activity of Ⅰb against oral squamous cell carcinoma cells is more obvious than that of Ⅰa.

Reproductive and developmental toxicities of 5-fluorouracil in model organisms and humans.

Chemotherapy, as an important clinical treatment, has greatly enhanced survival in cancer patients, but the side effects and long-term sequelae bother both patients and clinicians. 5-Fluorouracil (5-FU) has been widely used as a chemotherapeutic agent in the clinical treatment of various cancers, but several studies showed its adverse effects on reproduction. Reproductive toxicity of 5-FU often associates with developmental block, malformation and ovarian damage in the females. In males, 5-FU administration alters the morphology of sexual organs, the levels of reproductive endocrine hormones and the progression of spermatogenesis, ultimately reducing sperm numbers. Mechanistically, 5-FU exerts its effect through incorporating the active metabolites into nucleic acids directly, or inhibiting thymidylate synthase to disrupt the function of DNA and RNA, leading to profound effects on cellular metabolism and viability. However, some studies suggested that the toxicity of 5-FU on reproduction is reversible and certain drugs used in combination with 5-FU during chemotherapy could protect reproductive systems from 5-FU damage both in females and males. Herein, we summarise the recent findings and discuss underlying mechanisms of the 5-FU-induced reproductive toxicity, providing a reference for future research and clinical treatments.

Comparison of therapeutic efficacy and toxicity of docetaxel, cisplatin, and fluorouracil (TPF)-based induction chemotherapy plus concurrent chemoradiotherapy and chemoradiotherapy alone in locally advanced nasopharyngeal carcinoma.

Purpose:In recent years, docetaxel, cisplatin, and fluorouracil (TPF)-based induction chemotherapy plus concurrent chemoradiotherapy (CCRT) has been commonly applied for locally advanced nasopharyngeal carcinoma (LA-NPC). However, whether TPF+CCRT regimen is the best choice for LA-NPC remains unclear. This meta-analysis aims to elucidate and compare the efficacy and toxicity of TPF+CCRT versus CCRT alone for LA-NPC.Methods:Two investigators independently and systematically searched relevant studies available on PubMed, Embase, Cochrane Library, and Web of Science published before January 7, 2021. Data were extracted from eligible studies for assessing their qualities, and calculating pooled hazard ratios (HR), odds ratio (OR) and 95% confidence intervals (CI) using Review Manager software 5.3 (RevMan 5.3).Results:Five studies involving 759 LA-NPC patients were analyzed in the meta-analysis. Compared to CCRT alone, TPF-based IC plus CCRT significantly improved overall survival (OS) (HR = 0.53, 95% CI: 0.35–0.81, P = .003), progression-free survival (PFS) (HR = 0.63, 95% CI: 0.46–0.86, P = .004), distant metastasis-free survival (DMFS) (HR = 0.58, 95% CI: 0.39–0.86, P = .008), and locoregional failure-free survival (LRFFS) (HR 0.62, 95% CI: 0.43–0.90, P = .01). In addition, TPF-based IC plus CCRT mainly increased risks of grade 3/4 acute hematological toxicity and non-hematological toxicities like leukopenia (OR = 1.84, 95% CI: 0.42–8.03, P = .42), neutropenia (OR = 1.78, 95% CI: 0.23–13.82, P = .58), thrombocytopenia (OR = 1.76, 95% CI: 0.53–5.81, P = .35), febrile neutropenia (OR = 2.76, 95% CI: 0.07–101.89, P = .58), vomiting (OR = 18.94, 95% CI: 0.99–362.02, P = .05) and dry mouth (OR = 2.23, 95% CI: 0.22–22.57, P = .50), which were uncomplicated and manageable.Conclusions:TPF + CCRT is superb than CCRT alone for the management of LA-NPC. However, TPF+CCRT increases the incidences of grade 3/4 acute hematological toxicity and some non-hematological toxicities.

The effect of combined TPF and intensity modulated radiotherapy after TPF induction chemotherapy on locally advanced nasopharyngeal carcinoma: a retrospective analysis.

To evaluate the efficacy and toxicity of docetaxel, cisplatin, and fluorouracil (TPF) regimen followed by intensity modulated radiotherapy (IMRT) on locally advanced nasopharyngeal carcinoma (NPC). A total of 150 patients with locally advanced NPC [American Joint Committee on Cancer (AJCC) 2009 stage IIIa-IVb] received 2 or 3 cycles of a TPF regimen as induction chemotherapy. A group of 67 participants (TPF group) continued to receive TPF chemotherapy and radiotherapy, and the remaining 83 participants (P group) received cisplatin chemotherapy and radiotherapy. A median follow-up of 35 months (4-66 months) showed that there was no significant difference between P group and TPF group in progression-free survival (PFS) and overall survival (OS). The incidence rate of myelosuppression at 3-4 degrees was 16.9% and 34.3% in the P group and TPF group (P=0.029), respectively, and the oral mucosa reaction at 3-4 degrees was 18.1% and 37.3% in the P group and TPF group, respectively (P=0.007). The 3-4-degree skin reaction in the P group and TPF group was 15.7% and 29.9% (P=0.030), respectively. The rate of liver function injury in the P group was significantly lower than that in TPF group (P<0.05). Compared with concurrent cisplatin chemotherapy and radiotherapy, the concurrent TPF regimen and IMRT showed no significant improvement in OS and PFS in patients with advanced NPC, but exhibited more severe hematologic toxicity, oral mucosal responses, skin reactions, and liver functional impairment.

Pharmacokinetics and tolerance of repeated oral administration of 5-fluorocytosine in healthy dogs

Background5-fluorocytosine is a pyrimidine and a fluorinated cytosine analog mainly used as an antifungal agent. It is a precursor of 5-fluorouracil, which possesses anticancer properties. To reduce systemic toxicity of 5-fluorouracil during chemotherapy, 5- fluorocytosine can be used as a targeted anticancer agent. Expression of cytosine deaminase by a viral vector within a tumor allows targeted chemotherapy by converting 5-fluorocytosine into the cytotoxic chemotherapeutic agent 5-fluorouracil. However, little is known about the tolerance of 5-fluorocytosine in dogs after prolonged administration.ResultsIn three healthy Beagle dogs receiving 100 mg/kg of 5-fluorocytosine twice daily for 14 days by oral route, non-compartmental pharmacokinetics revealed a terminal elimination half-life of 164.5 ± 22.5 min at day 1 and of 179.2 ± 11.5 min, after 7 days of administration. Clearance was significantly decreased between day 1 and day 7 with 0.386 ± 0.031 and 0.322 ± 0.027 ml/min/kg, respectively. Maximal plasma concentration values were below 100 µg/ml, which is considered within the therapeutic margin for human patients. 5-fluorouracil plasma concentration was below the limit of detection at all time points. The main adverse events consisted of depigmented, ulcerated, exudative, and crusty cutaneous lesions 10 to 13 days after beginning 5-fluorocytosine administration. The lesions were localized to the nasal planum, the lips, the eyelids, and the scrotum. Histological analyses were consistent with a cutaneous lupoid drug reaction. Complete healing was observed 15 to 21 days after cessation of 5-fluorocytosine. No biochemical or hematological adverse events were noticed.ConclusionsLong term administration of 5-fluorocytosine was associated with cutaneous toxicity in healthy dogs. It suggests that pharmacotherapy should be adjusted to reduce the toxicity of 5-fluorocytosine in targeted chemotherapy.