Tipiracil – Combined Gastrointestinal Cancer Therapy
Tipiracil is a supportive pharmacological agent and a potent inhibitor of the enzyme thymidine phosphorylase. While it possesses no inherent antineoplastic activity on its own, it is a critical component of combination therapy designed to significantly potentiate the clinical effects of cytotoxic drugs. Without its intervention, the primary active substance would be degraded by the body almost instantaneously, failing to achieve any therapeutic objectives.
The mechanism of action of tipiracil involves the selective and irreversible blockade of the enzyme thymidine phosphorylase (TP). Normally, this enzyme actively participates in nucleoside metabolism and rapidly degrades trifluridine as soon as it enters the systemic circulation or the liver. Without the protection provided by tipiracil, trifluridine would be destroyed too quickly to accumulate in tumor tissue at the concentration required to arrest cancer cell division. Tipiracil effectively "shuts down" this catabolic pathway, thereby drastically increasing the bioavailability of the primary drug and maintaining stable high plasma levels over a prolonged period. Furthermore, modern research suggests that inhibiting TP may provide an additional anti-angiogenic effect, as this enzyme is functionally identical to the platelet-derived endothelial cell growth factor (PD-ECGF), which stimulates the growth of new capillaries within a tumor mass, ensuring its nutrient supply.
The medication is used exclusively as part of a fixed combination with trifluridine at a strictly defined molecular ratio of 1:0.5.
Indications
Tipiracil is utilized solely as part of combination therapy for the treatment of the following categories of adult patients:
- Metastatic Colorectal Cancer: treatment of colon or rectal cancer in patients who have previously been treated with fluoropyrimidine, oxaliplatin, and irinotecan-based chemotherapy, as well as appropriate targeted anti-VEGF and anti-EGFR biological agents.
- Metastatic Gastric Cancer: including adenocarcinoma of the gastroesophageal junction in patients who have previously received at least two lines of standard systemic therapy for advanced disease.
- Refractory Cases: application in clinical scenarios where the tumor demonstrates resistance to prior lines of conventional chemotherapy.
Dosage and administration
The dosing regimen for tipiracil is always inextricably linked to the dose of trifluridine contained within the same tablet formulation.
- Available Strengths: film-coated tablets containing 15 mg trifluridine / 6.14 mg tipiracil or 20 mg trifluridine / 8.19 mg tipiracil.
- Administration Schedule: the drug is taken twice daily (strictly within one hour after completing breakfast and dinner) for 5 consecutive days, followed by a mandatory two-day rest period.
- Cycling: this schedule is repeated for two weeks, followed by a rest period lasting 14 days. The complete treatment cycle spans 28 days.
- Dose Calculation: the treating oncologist calculates the required dosage based on the patient's individual body surface area (m²).
- Guidelines: tablets must be swallowed whole; it is strictly prohibited to break, crush, or chew them.
