Repurposed Drugs in Cancer Therapy: Old Medicines, New Hope

Repurposing Old Drugs for New Uses in Innovative Cancer Care

Repurposing existing medicines for cancer therapy is one of the most exciting developments in modern oncology. Many drugs originally designed for other illnesses show strong anti-cancer potential, often through surprising mechanisms like cutting off a tumor’s blood supply, boosting immunity, or directly triggering cancer cell death.

Here is a guide to the main categories of repurposed drugs being studied for cancer care. The hilighted drugs are our preferred ones.

🦟 Antimalarials

Artemisinin

• Extracted from Artemisia annua (sweet wormwood), a herb used in traditional Chinese medicine for over 2000 years.

• Available as a nutritional supplement (capsules, teas, tinctures).

• In the presence of iron, it produces reactive oxygen species (ROS) that selectively damage iron-rich cancer cells, such as cancer cells. This is another example of ferroptosis. See our post on ferroptosis.

• Also reduces angiogenesis (blood vessel growth to tumors).

• Studied in breast, lung, colon cancers, and leukemia.

Artesunate

• A semi-synthetic derivative of artemisinin, developed for more predictable potency and absorption.

• Approved globally as a malaria drug, available in tablets and injections.

• Anti-cancer effects include:

  • ROS generation (similar to artemisinin).

  • Sensitising tumors to chemotherapy and radiotherapy.

  • Immune modulation and anti-metastatic action.

• Clinical studies in colorectal, breast, and brain cancers show promising results.

Chloroquine / Hydroxychloroquine

• Long-used anti-malarials, also prescribed for autoimmune conditions like lupus.

• Block autophagy (a survival mechanism cancer cells use under stress).

• May make chemotherapy and immunotherapy more effective.

• Studied in pancreatic, breast, and glioblastoma patients.

💊 Non-Steroidal Anti-Inflammatories (NSAIDs)

Aspirin

• Classic pain reliever and heart-protective blood thinner.

• Blocks COX enzymes, reducing inflammation and metastasis.

• Strongest data in colorectal cancer prevention and recurrence reduction.

Celecoxib

• Prescription NSAID, specifically a COX-2 inhibitor.

• Cuts off tumor-supporting inflammation and angiogenesis.

• Studied in colorectal and lung cancers, often alongside chemotherapy.

🪱 Anti-Worm & Anti-Parasitic Drugs

Mebendazole

• Common anti-worm medicine.

• Disrupts microtubules inside cancer cells, similar to certain chemotherapy agents.

• Studied in glioblastoma, colon cancer, and melanoma.

Fenbendazole

• Veterinary version of mebendazole, widely used for animals.

• Works via the same microtubule disruption mechanism.

• Early lab and anecdotal human evidence in lung and brain cancers.

Ivermectin

• Anti-parasitic drug famous for treating river blindness and scabies.

• Interferes with cancer cell signaling, induces apoptosis, and boosts immune recognition.

• Early studies suggest promise, but clinical evidence in humans is still emerging.

❤️ Cardiovascular & Heart Drugs

Propranolol

• A beta-blocker used for hypertension, heart arrhythmias, and anxiety.

• Blocks stress hormones (adrenaline/noradrenaline) that fuel cancer growth and spread.

• Strongest evidence in angiosarcoma, melanoma, and breast cancer.

Statins (Atorvastatin, Simvastatin, etc.)

• Cholesterol-lowering drugs.

• Block the mevalonate pathway, which tumors use for growth.

• Evidence in breast, prostate, and ovarian cancers.

Nitroglycerin

• Long-used for angina and heart failure.

• Increases tumor oxygenation, making them more sensitive to chemo and radiotherapy.

• Studied in lung cancer.

🧬 Metabolic & Immune-Modulating Drugs

Metformin

• Diabetes drug.

• Activates AMPK pathway, reducing tumor energy supply and insulin signaling.

• Evidence in breast, prostate, colorectal, and pancreatic cancers.

Low-Dose Naltrexone (LDN)

• Standard naltrexone is used for addiction, but in low doses, it boosts endorphins and modulates the immune system.

• Reduces cancer-related inflammation and helps restore immune surveillance.

• Studied in breast, ovarian, and pancreatic cancers; widely used off-label for integrative oncology.

🧪 Other Repurposed Drugs

Doxycycline

• Broad-spectrum antibiotic.

• Targets cancer stem cells by interfering with mitochondrial function.

• Studied in breast and prostate cancers.

Disulfiram

• Originally for alcohol dependence (causes intolerance to alcohol).

• In the presence of copper, forms toxic compounds inside cancer cells.

• Studied in glioblastoma and metastatic breast cancer.

Cimetidine

• Stomach acid blocker for reflux and ulcers.

• Suppresses tumor-promoting histamine signaling and reduces metastasis.

• Best evidence in colorectal cancer (especially around surgery).

At Leicester Ozone Clinic, we can guide you in the science of repurposed cancer drugs and help you explore safe, evidence-informed integrative approaches.