Trifluridine

Absorption

After oral administration of LONSURF with [14C]-trifluridine, at least 57% of the administered trifluridine was absorbed. Following a single dose of LONSURF (35 mg/m2) in patients with advanced solid tumors, the mean times to peak plasma concentrations (Tmax) of trifluridine was around 2 hours. Trifluridine area under the concentration-time curve from time 0 to the last measurable concentration (AUC0-last) was approximately 3-fold higher and maximum concentration (Cmax) was approximately 2-fold higher after multiple dose administration (twice daily for 5 days a week with 2 days rest for 2 weeks followed by a 14-day rest, repeated every 4 weeks) than after single-dose administration.
Following a single oral administration of LONSURF at 35 mg/m2 in patients with cancer, the mean time to peak plasma concentration (Tmax) of trifluridine was around 2 hours. For the ophthalmic formulation, systemic absorption appears to be negligible. A standardized high-fat, high-calorie meal decreased trifluridine Cmax by approximately 40% but did not change trifluridine AUC compared to those in a fasting state in patients with cancer following administration of a single dose of LONSURF 35 mg/m2.
In a dose finding study (15 to 35 mg/m2 twice daily), the AUC from time 0 to 10 hours (AUC0-10) of trifluridine tended to increase more than expected based on the increase in dose.

Toxicity

Intravenous LD50 in rat was 2946 mg/kg . Oral LD50 in rat and mouse were > 4379mg/kg . Overdosage via ocular instillation is unlikely. The highest dose of orally-administered Lonsurf, trifluridine in combination with tipiracil, administered in clinical studies was 180 mg/m^2 per day. The primary anticipated complication of an overdose is bone marrow suppression. There is no known antidote for trifluridine overdose: in case of an overdose, management should include customary therapeutic and supportive medical intervention aimed at correcting the presenting clinical manifestations and preventing their possible complications . Based on the findings from animal studies, trifluridine may cause fetal toxicity when administered to pregnant patients .

Description

Trifluridine (trifluorothymidine, TFT), a fluorinated pyrimidine nucleoside, is an anti-herpesvirus agent and an antitumor antimetabolite agent. It is an analog of thymidine which inhibits thymidylate synthase possesses antiviral and anticancer activity. After phosphorylation by thymidine kinase, it is incorporated into DNA where it induces DNA-damage and interferes with repair enzymes. Enhances frame shift insertion and deletion in CRISPR genome editing in pluripotent stem cells.

Chemical properties

White to Off-White Solid

Originator

Trifluorothymidine ,Mann,W. Germany,1975

The Uses of Trifluridine

Trifluridine is used as anti-herpesvirus antiviral agent in ophthalmie preparations.

Indications

As a standalone product, trifluridine is used for the ophthalmic treatment of primay keratoconjunctivitis and recurrent epithelial keratitis due to herpes simplex virus, types 1 and 2.
Trifluridine is also available as a combination product with tipiracil, which is indicated either alone or in combination with bevacizumab for the treatment of adult patients with metastatic colorectal cancer who have been previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, an anti-VEGF biological therapy, and if RAS wild-type, an anti-EGFR therapy. This combination product is also used for adult patients with metastatic gastric or gastroesophageal junction adenocarcinoma and were previously treated with at least two prior lines of chemotherapy that included a fluoropyrimidine, a platinum, either a taxane or irinotecan, and if appropriate, HER2/neu-targeted therapy.

What are the applications of Application

Trifluorothymidine is a substrate used to study the specificity and kinetics of thymidine kinases

Background

Trifluridine is a fluorinated pyrimidine nucleoside that is structurally related to idoxuridine . It is an active antiviral agent in ophthalmic solutions used mainly in the treatment of primary keratoconjunctivitis and recurrent epithelial keratitis due to herpes simplex virus. It displays effective antiviral activity against Herpes simplex virus type 1 and 2 .
The combination product of trifluridine with tipiracil marketed as Lonsurf has been approved in Japan, the United States, and the European Union for the treatment of adult patients with metastatic colorectal cancer who have been previously treated with fluoropyrimidine-, oxaliplatin- and irinotecan-based chemotherapy, an anti-VEGF biological therapy, and if RAS wild-type, an anti-EGFR therapy. In the anticancer therapy, trifluridine acts as a thymidine-based nucleoside metabolic inhibitor that gets incorporated into DNA of cancer cells following cell uptake to aberrate DNA function during cell replication .

Definition

ChEBI: Trifluridine is a pyrimidine 2'-deoxyribonucleoside compound having 5-trifluoromethyluracil as the nucleobase. An antiviral drug used mainly in the treatment of primary keratoconjunctivitis and recurrent epithelial keratitis. It has a role as an antiviral drug, an antimetabolite, an EC 2.1.1.45 (thymidylate synthase) inhibitor and an antineoplastic agent. It is a nucleoside analogue, an organofluorine compound and a pyrimidine 2'-deoxyribonucleoside.

Indications

Trifluridine (Viroptic) is a fluorinated pyrimidine nucleoside that has in vitro activity against HSV-1 and HSV- 2, vaccinia, and to a lesser extent, some adenoviruses. Activation of trifluridine requires its conversion to the 5 monophosphate form by cellular enzymes.Trifluridine monophosphate inhibits the conversion of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP) by thymidylate synthetase. In addition, it competes with deoxythymidine triphosphate (dTTP) for incorporation by both viral and cellular DNA polymerases. Trifluridine-resistant mutants have been found to have alterations in thymidylate synthetase specificity.

brand name

Viroptic (Monarch).

Therapeutic Function

Antiviral (ophthalmic)

General Description

Trifluridine, 5-trifluoromethyl-29-deoxyuridine (Viroptic),is a fluorinated pyrimidine nucleoside that demonstrates invitro inhibitory activity against HSV-1 and HSV-2, CMV,vaccinia, and some adenoviruses.Trifluridine possesses atrifluoromethyl group instead of an iodine atom at the 5-position of the pyrimidine ring.
synthetase, and the biologically generated triphosphatecompetitively inhibits thymidine triphosphate incorporationinto DNA by DNA polymerase. In addition, trifluridine inits triphosphate form is incorporated into viral and cellularDNA, creating fragile, poorly functioning DNA.Trifluridine is approved in the United States for the treatmentof primary keratoconjunctivitis and recurrent epithelialkeratitis caused by HSV types 1 and 2. Topical trifluridineshows some efficacy in patients with acyclovir-resistantHSV cutaneous infections.

Biochem/physiol Actions

Trifluorothymidine is a thymidine analog and is light sensitive. TFT serves as a thymidine kinase substrate to study enzyme specificity and kinetics. Incorporation of phosphorylated TFT into DNA induces damage, making it useful for DNA repair studies. TFT may also be used in the inhibition of thymidylate synthase and in screening mutant thymidine kinase gene.. It elicits antitumor activity in gastrointestinal (GI) cancers and has therapeutic potential to treat herpetic keratitis.

Mechanism of action

Trifluorothymidine is a fluorinated pyridine nucleoside structurally related to idoxuridine. It has been approved by the U.S. FDA and is a potent, specific inhibitor of replication of HSV-1 in vitro. Its mechanism of action is similar to that of idoxuridine. Like other antiherpes drugs, it is first phos-phorylated by thymidine kinase to mono-, di-, and triphosphate forms, which are then incorporated into viral DNA in place of thymidine to stop the formation of late virus mRNA and subsequent synthesis of the virion proteins.

Pharmacokinetics

Trifluridine exhibits an antiviral effect against herpes simplex virus, types 1 and 2 and vacciniavirus both in vitro and in vivo . Some strains of adenovirus that contribute to the pathology of keratoconjunctivitis were shown to be susceptible to trifluridine in vitro . While there is evidence from a study that cross-resistance may develop between trifluridine and idoxuridine or vidarabine, trifluridine was shown to effective in treating dendritic ulcers in patients with herpetic keratitis who are unresponsive to idoxuridine or vidarabine based on the results from masked comparative trials . In nonclinical studies, trifluridine/tipiracil hydrochloride demonstrated antitumour activity against both 5-fluorouracil (5-FU) sensitive and resistant colorectal cancer cell lines . The cytotoxic activity of trifluridine and tipiracil against several human tumour xenografts show high correlation with the amount of trifluridine incorporated into DNA, indicating that the primary mechanism of action of trifluridine involves the direct incorporation into the cancer cell DNA . Trifluridine and tipiracil demonstrated anti-tumor activity against KRAS wild-type and mutant human colorectal cancer xenografts in mice .
In clinical studies comprised of patients with previously treated metastatic colorectal cancer, treatment of trifluridine in combination with tipiracil in addition to best supportive care over a 5- or 7-month period resulted in increased progression-free survival (PFS), overall response rate (ORR) and disease control rate (DCR) compared to placebo . In an open-label study, administration of trifluridine at the recommended dosage in patients with advanced solid tumors had no clinically relevant effect on QT/QTc prolongation compared with placebo . Two out of 48 patients displayed had QTc greater than 500 msec and 1 of 42 patients (2.4%) had a QTc increase from baseline greater than 60 msec .

Pharmacokinetics

Trifluorothymidine is a synthetic halogenated pyrimidine nucleoside, first synthesized as an antitumor agent. It inhibits enzymes of the DNA pathway and is incorporated into both cellular and progeny viral DNA, causing faulty transcription of late messenger RNA and the production of incompetent virion protein. It does not require a viral thymidine kinase for monophosphorylation and is far less selective and more toxic than other analogs. It is active against HSV-1 and HSV-2, vaccinia virus, CMV and possibly adenovirus. Trifluorothymidine, when given IV, shows a plasma half-life of 18 minutes and is excreted in the urine either unchanged or as the inactive metabolite 5-carboxyuracil. When applied as a 1% ophthalmic solution, it rapidly enters the aqueous humor of HSV-infected rabbits’ eyes but is cleared within 60–90 min.

Side Effects

The most frequent adverse reactions to trifluridine administration are transient burning or stinging and palpebral edema. Other adverse reactions include superficial punctate keratopathy, epithelial keratopathy, hypersensitivity, stromal edema, irritation, keratitis sicca, hyperemia, and increased intraocular pressure.
Trifluridine is mutagenic in vitro and carcinogenic and teratogenic when administered subcutaneously to animals. Topical trifluridine was not teratogenic in animal studies. Because it is applied topically in humans, the likelihood of systemic effects is low.

Synthesis

Trifluridine, 5-trifluoromethyl-1-(2-deoxyribofuranosyl)pyrimidin-2, 4-(1H.3H)-dione (36.1.22), is synthesized from 5-trifluoromethyluracil. This is synthesized by the following scheme. It begins with trifluoroacetone, from which the oxynitrile (36.1.16) is synthesized. Acetylation of this product gives the corresponding trifluoroacetate (36.1.16). Pyrrolysis of this compound gives trifluoromethylacrylonitrile (36.1.17). Adding to this dry hydrogen bromide in methanol solution in a process of which methanolysis of the nitrile group takes place the bromide 36.1.19 is obtained, which upon acidic hydrolysis undergoes heterocyclization to the dihydropyrimidine 36.1.20. Brominating of the obtained dihydropyrimidine with molecular bromine and subsequent dehydrobromination of the resulting product 36.1.21 on heating in dimethylformamide gives 5-trifluoromethyluracil (36.1.22). This is reacted with 2-deoxy-D-ribos-1-phosphate using the nucleoside phosphorylase enzyme, or by treating it with hyxamethyldisylazane and then with trichloromethylsilane to make 2,4- trimethylsilyloxy-5-trifluoromethyl pyrimidine (36.1.23).
Hexamethyldisilazane, which itself does not form trimethylsilyl ethers, is used because using a combination of two reagents leads to optimal yield of trimethylsilyl ethers. Reacting the resulting pyrimidine derivative with 3,5-bis-(4-nitrobenzoate)-2-deoxyribofuranosyl chloride in the presence of mercury (II) acetate makes the corresponding ditrimethylsilyloxy nucleoside, which when treated with an aqueous solution of potassium iodide to remove the protecting groups. The resulting product undergoes preliminary purification by chromatography, and then is treated with a methanol solution of diisopropylamine to remove the 4-nitrobenzoyl protection from the furanosyl part, giving the desired trifluridine.

Veterinary Drugs and Treatments

Trifluridine (trifluorothymidine; Viroptic?) is a pyrimidine nucleoside analog. It is structurally related to 2-deoxythymidine, the natural precursor of DNA synthesis. Trifluridine is poorly absorbed by the cornea and is virostatic. Viroptic? interrupts viral replication by substituting “nonsense” pyrimidine analogues. For this reason, a competent surface immunity is necessary to resolve ocular disease, with or without antiviral therapy. A recent in vitro study in which several strains of feline herpes virus were collected from the United States and were used to infect kidney epithelial cells showed that trifluridine was more effective at lower concentrations compared with several other agents. For this reason, trifluridine was the first choice drug employed in the treatment of feline herpes virus ocular disease for many years. Because of the topical toxicity associated with use of trifluridine in cats, its popularity has diminished greatly. In many milder cases, the irritation associated with topical trifluridine is more intense then the inflammation induced by viral infection. Antiviral agents have also been used in the treatment of superficial punctate keratitis in the horse, thought to be associated with equine herpes virus-2 (EHV-2) infection of the cornea.

Metabolism

Trifluridine is not metabolized by cytochrome P450 (CYP) enzymes. Trifluridine is mainly eliminated by metabolism via thymidine phosphorylase to form an inactive metabolite, 5-(trifluoromethyl) uracil (FTY). No other major metabolites were detected in plasma or urine. Other minor metabolites, such as 5-carboxy-2'-deoxyuridine found on the endothelial side of the cornea or 5-carboxyuraci, were also detected, but only at low or trace level in plasma and urine.

References

1) Bijnsdorp et al. (2010), Differential activation of cell death and autophagy results in an increased cytotoxic potential for trifluorothymidine compared to 5-fluorouracil in colon cancer cells; Int. J. Cancer, 126 2457
2) Temmink et al. (2010), Trifluorothymidine resistance is associated with decreased thymidine kinase and equilibrative nucleoside transporter expression or increased secretory phospholipase A2; Mol. Cancer Ther., 9 1047
3) Suzuki et al. (2011), Mode of action of trifluorothymidine (TFT) against DNA replication and repair enzymes; Int. J. Oncol., 39 263 4) Yu et al. (2015), Small molecules enhance CRISPR genome editing in pluripotent stem cells; Cell Stem Cell, 16 142