thymidine phosphorylase

Thymidine phosphorylase is inhibited by the drug tipiracil. Tipiracil increases trifluridine exposure by preventing thymidine phosphorylase from metabolizing the drug. A brand-new oral treatment for metastatic colorectal cancer combines trifluridine and piracil[2]. As a thymidine phosphorylase inhibitor, tipiracil has a first-pass effect that prevents FTD from degrading[3].

HeLa cells are plated in triplicate in 96-well plates at a density of 500 cells/180 μL/well and pre-cultured for 24 hours before receiving 20 μL of each drug solution for 24 or 72 hours. Following the 24 h treatment, cells are washed with phosphate-buffered saline (PBS) before being added to each well with drug-free medium and being incubated for an additional 48 h. A Cell Counting Kit-8 is used to assess the inhibition of cell growth. SAS[3] is used to determine the 50% inhibitory concentration (IC50) values from the absorbance data.

Absorption, Distribution and Excretion
Tilpirimidine is primarily absorbed via the gastrointestinal tract. Following a single dose of 35 mg/m² of TAS-102 (containing tilpirimidine and trifluorouridine), the area under the absorption curve (AUC) of tilpirimidine was 301 ng·h/ml, the maximum plasma concentration (Cmax) was 69 ng/ml, and the time to peak concentration (Tmax) was 3 hours. Consumption of high-fat, high-calorie foods reduced Cmax and AUC by 40%. A standardized high-fat, high-calorie diet resulted in approximately a 40% reduction in Cmax and AUC of tilpirimidine in cancer patients after a single dose of LONSURF 35 mg. Following a single oral dose of LONSURF (60 mg) with [14C]-tilpirimidine hydrochloride, 77% of the radioactivity was recovered, of which 27% was excreted in the urine and 50% in the feces. Tipiracil is the main component in urine and feces, with 6-hydroxymethylaminomethane (6-HMU) being the major metabolite. In patients with advanced solid tumors, the apparent volume of distribution (Vd/F) of tilpyrimidine hydrochloride after a single dose of LONSURF (35 mg/m²) was 333 L. The oral clearance (CL/F) of tilpyrimidine hydrochloride after a single dose of LONSURF (35 mg/m²) was 109 L/hr. Metabolism/Metabolites Tipiracil undergoes minimal first-pass metabolism. It is not metabolized by the liver or hepatocytes, nor by cytochrome P450 enzymes. The only tilpyrimidine metabolite present in extremely low amounts in human plasma, urine, or feces is 6-hydroxymethyluracil (6-HMU), but this metabolite is not specific to tilpyrimidine. It is presumed to be produced by Enterobacteriaceae. In plasma, the proportions of these two metabolites were: tepyrimidine 53.1% and 6-HMU 30.9%.
Biological half-life
After administration of LONSURF 35 mg/m², the mean elimination half-life and steady-state half-life (t_1/2) of tepyrimidine were 2.1 hours and 2.4 hours, respectively.

Protein Binding

Tipiracil has a plasma protein binding rate of less than 8%.

[1]. Thymidine phosphorylase influences [(18)F]fluorothymidine uptake in cancer cells and patients with non-small cell lung cancer. Eur J Nucl Med Mol Imaging. 2014 Jul;41(7):1327-35.

[2]. Lonsurf (Trifluridine plus Tipiracil): A New Oral Treatment Approved for Patients with Metastatic Colorectal Cancer. Am Health Drug Benefits. 2016 Mar;9(Spec Feature):97-100.

[3]. Repeated oral dosing of TAS-102 confers high trifluridine incorporation into DNA and sustained antitumor activity in mouse models. Oncol Rep. 2014 Dec;32(6):2319-26.

Tipiracil belongs to the pyrimidinone class of compounds and is a compound in which uracil is substituted at the 5 and 6 positions with chlorine and (2-iminopyrrolidone-1-yl)methyl groups, respectively. It (in hydrochloride form) is used in combination with the nucleoside metabolism inhibitor trifluorouridine for the treatment of advanced/recurrent unresectable colorectal cancer. It is an antitumor drug and also an EC 2.4.2.4 (thymidine phosphorylase) inhibitor. It is a pyrimidinone, organochlorine, carboxymidine, and pyrrolidine compound. Functionally, it is related to uracil. It is the conjugate base of tilpyrimidine (1+). Tipiracil is a thymidine phosphorylase inhibitor. When used in combination with trifluorouridine in a 1:0.5 ratio, it forms TAS-102. The primary action of tilpyrimidine in TAS-102 is to enhance the bioavailability of trifluorouridine by inhibiting its catabolism. TAS-102 is indicated for the treatment of metastatic colorectal cancer in patients who have previously received fluorouracil, oxaliplatin, and irinotecan chemotherapy, or anti-VEGF or anti-EGFR therapy. Tipiracil is a thymidine phosphorylase inhibitor. Its mechanism of action is as a thymidine phosphorylase inhibitor.

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Drug Indications
Tipiracil can also be used in combination with [trifluoperidine], either alone or in combination with [bevacizumab], for the treatment of adult patients with metastatic colorectal cancer who have previously received fluorouracil, oxaliplatin, and irinotecan chemotherapy, anti-VEGF biotherapy, and (if RAS wild-type) anti-EGFR therapy. This combination therapy is also indicated for the treatment of adult patients with metastatic gastric or gastroesophageal junction adenocarcinoma who have previously received at least two lines of chemotherapy (including fluorouracil, platinum, taxanes, or irinotecan, and, where appropriate, HER2/neu targeted therapy).
FDA Label

Mechanism of Action

Tipiramycin is a thymidine phosphorylase inhibitor. Its function is to prevent the breakdown of the active ingredient of trifluorouridine, thereby increasing the bioavailability of trifluorouridine and enhancing its systemic concentration. Furthermore, thymidine phosphorylase is reported to be an angiogenic factor, typically overexpressed in solid tumors. Thymidine phosphorylase is directly associated with poor prognosis; tumors with elevated enzyme expression tend to have increased angiogenesis and are therefore more malignant. Therefore, studies have shown that tilpyrimidine plays an additional role by downregulating tumor angiogenesis.
Pharmacodynamics

Tipiramycin prevents the conversion of trifluorouridine to 5-trifluoromethyl-2,4(1H,3H)-pyrimidinidone (an inactive major metabolite) by inhibiting thymidine phosphorylase. Therefore, tilpyrimidine can improve the bioavailability of trifluorouridine. On the other hand, thymidine phosphorylase is a known platelet-derived endothelial growth factor; inhibiting this enzyme can produce an indirect anti-angiogenic effect.

C9H11N4O2CL

242.66224

242.057

183204-74-2

Trifluridine/tipiracil hydrochloride mixture;733030-01-8;Tipiracil hydrochloride;183204-72-0

6323266

White to off-white solid

1.7±0.1 g/cm3

245ºC (decomposition)

1.743

-1.37

3

3

2

16

404

0

O=C1NC(C(Cl)=C(CN2C(CCC2)=N)N1)=O

QQHMKNYGKVVGCZ-UHFFFAOYSA-N

InChI=1S/C9H11ClN4O2/c10-7-5(12-9(16)13-8(7)15)4-14-3-1-2-6(14)11/h11H,1-4H2,(H2,12,13,15,16)

5-chloro-6-[(2-iminopyrrolidin-1-yl)methyl]-1H-pyrimidine-2,4-dione

Tipiracil

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

H2O: ~1 mg/mL (~4.1 mM)
DMSO: <1 mg/mL

Solubility in Formulation 1: 2 mg/mL (8.24 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)