Toceranib Phosphate

Tyrosine Kinase Inhibitor Receptor Tyrosine Kinase Inhibitor

Dosage & Administration Guidelines

Species Route Dose Frequency Duration & Clinical Notes
Dog PO 3.25 mg/kg (range 2.75-3.5 mg/kg) Every other day (q48h) Duration: Continuous until disease progression or unacceptable toxicity; typically 4-6 weeks for initial response assessment
Notes: Administer with food to enhance absorption. Dose may be reduced to 2.75 mg/kg or increased to 3.5 mg/kg based on tolerance and response. For mast cell tumors, treatment is often continued for at least 6 months.
Cat PO 2.5-3.0 mg/kg Every other day (q48h) Duration: Continuous until disease progression or unacceptable toxicity
Notes: Limited data; use with caution. Monitor for gastrointestinal and hematologic adverse effects.

Clinical Indications & Species Uses

General Indications
  • Targeted therapy for tyrosine kinase-driven tumors, particularly mast cell tumors in dogs
Dog (Canine)
  • Treatment of Patnaik grade II or III recurrent, cutaneous mast cell tumors with or without regional lymph node involvement
  • Treatment of various solid tumors (off-label): anal sac adenocarcinoma, thyroid carcinoma, head and neck squamous cell carcinoma, metastatic osteosarcoma, and others

Pharmacology & Mechanism of Action

Drug Class: Tyrosine Kinase Inhibitor | Pharmacological Group: Receptor Tyrosine Kinase Inhibitor

Mechanism of Action: Toceranib phosphate is a small-molecule receptor tyrosine kinase inhibitor that selectively inhibits several receptor tyrosine kinases, including vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), and stem cell factor receptor (c-Kit). By competitively binding to the ATP-binding site of these kinases, toceranib blocks downstream signaling pathways that promote tumor angiogenesis, tumor cell proliferation, and survival. In particular, inhibition of c-Kit is important in canine mast cell tumors, where activating mutations in c-Kit drive tumor growth. Toceranib also inhibits the kinase activity of Flt-3 and CSF-1R, contributing to its antitumor and immunomodulatory effects.

Pharmacodynamics: Toceranib exhibits dose-dependent inhibition of target kinases. In canine mast cell tumors, toceranib induces apoptosis and reduces tumor vascularity. It has been shown to decrease tumor size and delay disease progression in various solid tumors. The drug also modulates the tumor microenvironment by inhibiting angiogenesis and may enhance antitumor immune responses. Pharmacodynamic effects are observed at plasma concentrations that correlate with clinical efficacy, and the drug's activity is influenced by the presence of specific c-Kit mutations.

⚡ Pharmacokinetics Summary

Absorption: Toceranib is administered orally and is absorbed with a bioavailability of approximately 77% in dogs. Peak plasma concentrations are reached within 2-4 hours after oral administration. Food can increase absorption, so it is recommended to administer with food to enhance systemic exposure.
Distribution: Toceranib is extensively distributed into tissues, with a large volume of distribution. It is highly protein-bound (approximately 91-93% in dogs). The drug crosses the blood-brain barrier to a limited extent.
Metabolism: Toceranib is primarily metabolized in the liver via oxidative metabolism, mainly by cytochrome P450 enzymes (CYP3A4). Several metabolites are formed, some of which may have pharmacological activity.
Excretion: Toceranib is eliminated primarily via the biliary route into feces, with a smaller amount excreted in urine. The terminal half-life in dogs is approximately 17-24 hours, allowing for alternate-day dosing.
Half-Life: Dogs: approximately 17-24 hours; Cats: approximately 15-20 hours (extrapolated); Other species: not well established.
Bioavailability: Approximately 77% in dogs when administered orally.
Protein Binding: Approximately 91-93% in dogs.

Available Formulations & Strengths

Oral Tablet 10 mg, 15 mg, 50 mg (PO)

Contraindications & Clinical Warnings

Contraindications:
  • Hypersensitivity to toceranib or any component of the formulation
  • Use in animals with severe hepatic impairment
  • Use in animals with severe renal impairment
  • Use in pregnant or lactating animals (teratogenic potential)
  • Concurrent use with other tyrosine kinase inhibitors or strong CYP3A inhibitors (e.g., ketoconazole) without dose adjustment
Warnings & Clinical Precautions:
  • Toceranib is a potent drug; handle with care, avoid skin contact, and wash hands after administration.
  • Do not split or crush tablets; wear gloves if handling broken tablets.
  • Use with caution in animals with pre-existing gastrointestinal disease, as it can cause vomiting, diarrhea, and anorexia.
  • Monitor complete blood count and serum biochemistry regularly (at least monthly) for neutropenia, thrombocytopenia, and elevated liver enzymes.
  • May cause proteinuria; monitor urine protein:creatinine ratio periodically.
  • Use with caution in animals with cardiac disease, as hypertension and thromboembolic events have been reported.
  • Not for use in food animals; withdrawal times are not established.
  • In cats, monitor for signs of renal toxicity and gastrointestinal upset.

Adverse Effects & Reactions

Common:

  • Vomiting
  • Diarrhea
  • Anorexia
  • Weight loss
  • Lethargy
  • Neutropenia
  • Thrombocytopenia
  • Elevated liver enzymes (ALT, AST)

Serious / Severe:

  • Gastrointestinal perforation or hemorrhage
  • Severe neutropenia with fever (febrile neutropenia)
  • Thromboembolism (pulmonary embolism, stroke)
  • Hypertension
  • Protein-losing nephropathy
  • Hepatotoxicity
  • Pancreatitis

Rare:

  • Interstitial pneumonia
  • Cutaneous reactions (erythema, pruritus)
  • Seizures
  • Cardiac arrhythmias
  • Bone marrow aplasia

Key Drug Interactions

Interacting Drug / Class Clinical Effect & Mechanism Severity
Strong CYP3A inhibitors (e.g., ketoconazole, itraconazole, clarithromycin) May increase toceranib plasma concentrations, increasing risk of toxicity. Dose reduction or alternative therapy should be considered. High
CYP3A inducers (e.g., phenobarbital, rifampin) May decrease toceranib plasma concentrations, reducing efficacy. Monitor therapeutic response. Moderate
Nonsteroidal anti-inflammatory drugs (NSAIDs) Increased risk of gastrointestinal ulceration and bleeding due to additive effects on the GI mucosa. Moderate
Corticosteroids May increase risk of gastrointestinal ulceration and immunosuppression. Use with caution. Moderate
Other myelosuppressive agents (e.g., chemotherapy) Additive bone marrow suppression. Monitor blood counts closely. High

Overdose & Toxicity Management

Signs of Toxicity:

  • Severe vomiting and diarrhea
  • Bone marrow suppression (neutropenia, thrombocytopenia)
  • Gastrointestinal hemorrhage
  • Hepatotoxicity
  • Hypotension or hypertension
  • Seizures (in severe cases)

Emergency Treatment Protocol: There is no specific antidote for toceranib overdose. Treatment is symptomatic and supportive. Induce emesis if ingestion is recent (within 2 hours) and the animal is conscious. Administer activated charcoal to reduce absorption. Provide intravenous fluids for dehydration and electrolyte imbalances. Manage gastrointestinal signs with antiemetics (e.g., maropitant) and gastroprotectants (e.g., omeprazole, sucralfate). Monitor complete blood count, serum biochemistry, and blood pressure. In cases of severe neutropenia, consider granulocyte colony-stimulating factor (G-CSF) and broad-spectrum antibiotics. Hospitalization and intensive care may be required.

Food Animal Withdrawal Times

Toceranib is not approved for use in food animals. Withdrawal times have not been established. Do not use in animals intended for human consumption.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20°C to 25°C (68°F to 77°F); excursions permitted between 15°C and 30°C (59°F and 86°F).

Handling & Special Conditions: Keep in original container, tightly closed, and protect from moisture. Do not remove desiccant. Keep out of reach of children and pets.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: FDA-approved for use in dogs (Palladia) for the treatment of mast cell tumors.

Extra-Label (Off-Label) Use: In the United States, toceranib is FDA-approved for use in dogs only. Extra-label use in other species is permitted under the Animal Medicinal Drug Use Clarification Act (AMDUCA) provided a valid veterinarian-client-patient relationship exists, and appropriate withdrawal times are considered for food animals. However, due to lack of residue data, use in food animals is strongly discouraged.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Toceranib phosphate (Palladia) is a first-in-class veterinary tyrosine kinase inhibitor used primarily for canine mast cell tumors. It is also used off-label for various other solid tumors. The drug is generally well-tolerated, but adverse effects are common and may require dose adjustments or supportive care. Baseline and periodic monitoring should include complete blood count, serum biochemistry, urinalysis with protein:creatinine ratio, and blood pressure. Dose reductions or treatment interruptions are recommended for significant toxicities. Response to therapy should be evaluated at 4-6 weeks, with continued treatment if there is clinical benefit. Toceranib should be used with caution in animals with pre-existing organ dysfunction. Client education on handling and administration is essential. Due to its mechanism of action, toceranib may also have immunomodulatory effects, and ongoing research is exploring its use in combination with other therapies.

References & Literature

  • 📚 Plumb's Veterinary Drug Handbook
  • 📚 Papich Veterinary Pharmacology and Therapeutics
  • 📚 Compendium of Veterinary Products (CVP)
  • 📚 Palladia (toceranib phosphate) FDA label
  • 📚 London CA, et al. Toceranib phosphate for the treatment of canine mast cell tumors. Clin Cancer Res. 2009;15(11):3856-3865.