Raltitrexed, also known by the brand name Tomudex, is a chemotherapy medication. It belongs to a class of drugs called antimetabolites, which interfere with the normal growth processes of cells. This medication works by disrupting the ability of cancer cells to synthesize DNA, hindering their rapid division and proliferation.
What Raltitrexed Treats
Raltitrexed is primarily used for treating advanced colorectal cancer, particularly in situations where other common chemotherapy agents like fluorouracil are not suitable or tolerated. This includes patients who have experienced severe cardiotoxicity or other significant adverse reactions to fluorouracil-based treatments. Raltitrexed can be considered for both adjuvant therapy, which is given after initial treatment to reduce recurrence risk, and palliative chemotherapy for locally advanced or metastatic disease. Its use offers an alternative for patients who cannot continue standard 5-fluorouracil regimens.
How Raltitrexed Works
Raltitrexed functions as an antifolate drug, mimicking folic acid, a vitamin necessary for DNA synthesis. It targets and inhibits an enzyme called thymidylate synthase (TS). Thymidylate synthase is responsible for converting deoxyuridine monophosphate (dUMP) into deoxythymidine monophosphate (dTMP), a molecule required for building DNA.
Once inside cancer cells, raltitrexed undergoes a process called polyglutamation, which enhances its inhibitory effect and increases its retention. By blocking this enzyme, raltitrexed prevents dTMP formation, thereby disrupting DNA replication and repair. This disruption leads to what is known as “thymineless death” in rapidly dividing cancer cells, causing DNA damage, cell cycle arrest, and programmed cell death. Cancer cells are vulnerable to this mechanism due to their high rate of division and continuous need for DNA synthesis.
Administering Raltitrexed
Raltitrexed is administered intravenously as an infusion, typically by a chemotherapy nurse. The medication is usually diluted in 50 to 250 mL of 0.9% sodium chloride or 5% dextrose solution. The infusion is generally given over a 15-minute period.
Treatment with raltitrexed usually follows a cycle of every three weeks, where patients receive the infusion on day one and then have a 20-day rest period without treatment. Before each treatment cycle, healthcare professionals will perform blood tests to check blood cell counts, liver transaminases, serum bilirubin, and serum creatinine levels. Dosing adjustments or delays may be necessary if blood counts are not within acceptable ranges or if significant toxicity is present.
Potential Side Effects
Raltitrexed, like other chemotherapy agents, can cause a range of side effects, which vary among individuals. Gastrointestinal issues are common, including nausea, vomiting, and diarrhea, which can range from mild to severe and may require anti-sickness medications or other supportive care. Some patients may also experience constipation, abdominal pain, or a sore mouth and throat (mucositis).
Bone marrow suppression is another frequently observed side effect, resulting in reduced production of blood cells. This can manifest as anemia (low red blood cell count) leading to fatigue and breathlessness, leukopenia (low white blood cell count) increasing the risk of infection, and thrombocytopenia (low platelet count) causing easy bruising and bleeding. Regular blood tests are performed to monitor these changes, and treatment may be adjusted or delayed if counts are too low.
Liver function changes, indicated by elevated liver enzymes, can occur but are generally mild and reversible once treatment concludes. Other possible side effects include skin reactions like rashes and itching, fatigue, loss of appetite leading to weight loss, and flu-like symptoms such as fever, chills, and headaches. Patients should report any side effects to their healthcare provider for appropriate management, which might include temporary treatment breaks or dose reductions.