Axitinib

Introduction Overview

Generic Name

axitinib

Brand Name

Inlyta

Dosage Form

oral tablet

Drug Class

Multikinase inhibitors, VEGF/VEGFR inhibitors

Pharmacokinetics

Absorption:
Axitinib is rapidly absorbed following oral administration, with peak plasma concentrations typically reached within 2 to 6 hours post-dose. It demonstrates moderate bioavailability, and the rate of absorption may be moderately affected by food intake, though administration with or without food does not significantly impact overall exposure. The drug is consistently absorbed across patients, making once or twice-daily dosing feasible. Factors such as gastrointestinal pH and motility can slightly alter absorption but not to a clinically meaningful extent.

Distribution:
Once absorbed, axitinib exhibits extensive plasma protein binding, primarily to albumin, exceeding 99%. The volume of distribution (Vd) suggests moderate tissue penetration, allowing effective targeting of tumor sites. The drug distributes into peripheral compartments but does not significantly accumulate in red blood cells or cerebrospinal fluid. Distribution characteristics facilitate effective targeting of tumor vasculature, although limited central nervous system penetration is expected.

Metabolism:
Axitinib undergoes extensive hepatic metabolism predominantly via the cytochrome P450 enzyme CYP3A4/5, with minor contributions from CYP1A2, CYP2C19, and UGT1A1-mediated glucuronidation pathways. Metabolites include a mixture of hydroxylated and demethylated compounds that are less pharmacologically active. Hepatic impairment can lead to altered metabolism and increased exposure, necessitating caution or dose adjustments in severe liver dysfunction. Axitinib’s reliance on CYP3A4 for metabolism renders it susceptible to interactions with CYP3A4 inhibitors and inducers, which can significantly modify plasma levels.

Elimination:
The elimination of axitinib and its metabolites occurs primarily via biliary and fecal routes, with minimal renal excretion of unchanged drug (<20%). The terminal half-life ranges from approximately 2.5 to 6 hours, supporting a twice-daily dosing regimen to maintain steady plasma concentrations. Renal impairment appears to have limited impact on elimination, and no starting dose adjustment is generally required in patients with mild to severe renal dysfunction. Axitinib's clearance may be influenced by hepatic function and concurrent medications, reflective of its metabolism via CYP450 enzymes.

Dosage Forms

Available Dosage Forms:
Inlyta is available as oral immediate-release tablets. Specific tablet strengths include 1 mg, 3 mg, 5 mg, and 7 mg.

Dosages for Adults and Adolescents:
The recommended adult dosing for advanced renal cell carcinoma is an initial dose of 5 mg orally twice daily, approximately 12 hours apart. Dose titration can be implemented up to 10 mg twice daily or down to 2 mg twice daily based on individual tolerability and safety parameters such as blood pressure, organ function, and adverse effects. The dosing adjustments aim to optimize therapeutic response while minimizing toxicity.

Specific Patient Populations:
No dosage adjustment is necessary for patients with mild or moderate renal impairment; however, data are limited in severe renal impairment. In patients with hepatic impairment, particularly moderate to severe dysfunction, caution is advised, and dose adjustments may be necessary due to increased drug exposure. The safety and efficacy of Inlyta have not been established in pediatric populations; therefore, its use is not recommended in children. Patients with advanced liver impairment require careful monitoring. Additionally, dosing must be modified or temporarily withheld prior to surgical procedures to minimize bleeding risk.

Mechanism Of Action

Axitinib, the active pharmaceutical ingredient in Inlyta, is a potent and selective inhibitor of vascular endothelial growth factor receptors (VEGFR) 1, 2, and 3. These receptor tyrosine kinases are critical mediators of angiogenesis, the process by which new blood vessels form from pre-existing vasculature, a mechanism essential for tumor growth and metastasis. Axitinib binds competitively to the ATP-binding site of these receptors, inhibiting their kinase activity and thereby abrogating downstream signaling pathways involved in endothelial cell proliferation, migration, and survival.

At the cellular level, this inhibition blocks VEGF-driven signaling cascades such as the MAPK/ERK and PI3K/AKT pathways, resulting in reduced angiogenic responses and vascular permeability. By impeding neovascularization, axitinib effectively starves tumors of the oxygen and nutrients necessary for their continued growth and metastatic potential. This targeted mechanism differentiates it from traditional cytotoxic chemotherapy agents that non-selectively attack dividing cells.

Biochemically, axitinib's role as a multikinase inhibitor extends to selectivity against other kinases like platelet-derived growth factor receptor (PDGFR) and c-Kit, though with less potency. This multikinase activity may contribute to a broader anti-tumor effect but also accounts for some off-target toxicities observed clinically. Comparative to other VEGFR inhibitors, axitinib exhibits a higher binding affinity and inhibitory potency, which correlates with its pronounced pharmacodynamic effects.

Clinical studies have demonstrated that blockade of the VEGF/VEGFR axis via axitinib substantially improves progression-free survival in advanced renal cell carcinoma. The clinical efficacy validates the mechanistic rationale, as tumors highly dependent on angiogenesis show measurable response and regression. Ongoing research continues to explore combination strategies with immunotherapies to synergize anti-angiogenic and immune-mediated tumor control, reflecting evolving understanding of the complex tumor microenvironment.

Pharmacological Actions

Inhibits vascular endothelial growth factor receptors (VEGFR-1, VEGFR-2, VEGFR-3) tyrosine kinase activity.
Blocks tumor angiogenesis resulting in reduced blood supply to cancer cells.
Exerts anti-proliferative effects on endothelial cells by disrupting VEGF signaling pathways such as MAPK/ERK and PI3K/AKT.
Inhibits additional receptor tyrosine kinases including PDGFR and c-Kit at lower potency, contributing to anti-tumor activity.
Demonstrates potent and selective inhibition of kinase activity with high binding affinity to VEGFR.
Induces tumor starvation by decreasing oxygen and nutrient delivery through impaired neovascularization.
Modulates tumor microenvironment to reduce metastatic progression associated with abnormal blood vessel formation.
Exhibits targeted action compared to cytotoxic chemotherapeutic agents, resulting in a more favorable toxicity profile.
Potentiates anti-tumor immune responses when combined with immunotherapies by altering tumor vasculature.
Improves progression-free survival in advanced renal cell carcinoma through sustained VEGFR blockade.
Reduces vascular permeability and edema associated with VEGF-mediated signaling.
Influences downstream cellular processes including endothelial cell migration, survival, and differentiation.
Has dose-dependent biological activity supporting individualized titration in clinical use.

Therapeutic Or Clinical Uses

Treatment of advanced renal cell carcinoma (RCC) after failure of at least one prior systemic therapy.
Used as part of combination therapy with agents such as pembrolizumab or avelumab for first-line treatment of advanced RCC.
Employed in cases where targeted anti-angiogenic therapy is indicated to inhibit tumor growth and progression.
Reduces tumor vascularization resulting in delayed disease progression and tumor shrinkage in kidney cancer.
Serves as a second-line or later treatment option following resistance or intolerance to cytokine therapies or other TKIs.
Used to improve progression-free survival in patients with metastatic RCC.
Applied in clinical trials exploring efficacy in other VEGF-dependent tumors.
Off-label exploration in other solid tumors where VEGF/VEGFR pathways are implicated.
Potential therapeutic option in patients unsuitable for conventional chemotherapy due to side effect profile.
Contributes to multimodal cancer treatment strategies combining targeted therapy with immunotherapy or chemotherapy.
Helps manage disease in patients with advanced kidney cancer who have limited treatment options.
Assists in maintaining quality of life by controlling tumor progression with oral administration.
May be used in clinical settings to assess individualized patient response via dose modification.

Side Or Adverse Effects

Hypertension (increased blood pressure) observed frequently, requiring monitoring and management.
Gastrointestinal disturbances including nausea, vomiting, diarrhea, and constipation.
Liver function abnormalities manifested as elevated liver enzymes, jaundice, or hepatotoxicity.
Fatigue and weakness common among patients during therapy.
Mucosal inflammation such as stomatitis, mouth sores, and inflammation of nasal, ocular, or gastrointestinal mucosa.
Hand-foot syndrome characterized by rash, redness, itching, and peeling skin on the palms and soles.
Severe bleeding events including gastrointestinal hemorrhage, hemoptysis, or other organ bleeds.
Rare but serious events such as gastrointestinal perforation or fistula formation.
Cardiovascular events including chest pain, heart failure symptoms, and arrhythmias.
Thyroid dysfunction including both hypothyroidism and hyperthyroidism, necessitating thyroid function monitoring.
Hematologic abnormalities such as easy bruising, unusual bleeding, or thrombocytopenia.
Headaches, dizziness, confusion, or seizures reported in some patients.
Weight loss and decreased appetite, contributing to general malaise.
Respiratory symptoms like cough and shortness of breath due to vascular or inflammatory effects.
Allergic reactions including hives, facial swelling, or anaphylaxis in rare cases.

Precautions

Monitor blood pressure regularly due to risk of hypertension; manage elevated readings promptly.
Conduct baseline and periodic liver function tests to detect hepatotoxicity early.
Assess thyroid function before and during treatment to identify and manage dysfunction.
Evaluate cardiovascular status, especially in patients with prior heart disease or risk factors.
Avoid concurrent use with strong CYP3A4 inhibitors or inducers to prevent altered axitinib levels.
Use effective contraception during treatment and for at least one week after discontinuation due to teratogenic risk.
Avoid administering to pregnant or breastfeeding women given potential for fetal harm and neonatal exposure.
Inform surgical teams to withhold the drug at least 24 hours prior to surgical procedures to decrease bleeding or wound healing complications.
Patients with gastrointestinal risks such as perforations or fistulas require careful assessment before prescribing.
Caution advised in patients with bleeding disorders or active hemorrhage due to increased bleeding risk.
Assess renal function before treatment, though no starting dose adjustment is typically needed for renal impairment.
Instruct patients not to consume grapefruit products to avoid pharmacokinetic interactions.
Monitor for symptoms of severe adverse reactions such as gastrointestinal perforation or severe bleeding.
Ensure proper hydration and nutrition to minimize gastrointestinal side effects.
Advise patients to report new symptoms promptly, including signs of infection, bleeding, or cardiovascular events.

Warnings

Use is contraindicated in pregnancy due to risk of fetal harm, including birth defects and miscarriage.
Axitinib use by either parent can cause teratogenicity; effective contraception is mandatory.
Increased risk of serious and potentially fatal bleeding events; patients should promptly report signs of bleeding.
Potential for gastrointestinal perforation or fistula formation, which can be life-threatening.
Regular monitoring of blood pressure is critical as hypertension is a common and serious side effect.
Severe liver injury can occur; early detection through laboratory tests is vital.
Risk of cardiovascular events including heart attack, heart failure, and stroke, especially in susceptible individuals.
Discontinue therapy at least 24 hours prior to scheduled surgeries to reduce hemorrhagic or wound healing complications.
Drug may cause thyroid dysfunction necessitating ongoing monitoring and appropriate management.
Use caution in patients with bleeding disorders or those receiving anticoagulants due to additive bleeding risk.
Avoid breast-feeding while on treatment and for at least 2 weeks after the last dose.
Not evaluated for safety and efficacy in pediatric populations; usage in children is not recommended.
Possibility of severe hypersensitivity or allergic reactions including anaphylaxis.
Severe gastrointestinal symptoms such as persistent vomiting or diarrhea require medical evaluation.
Dose modifications or discontinuation may be required for intolerable or severe adverse effects.

Contraindication

Known hypersensitivity or allergy to axitinib or any of its excipients.
Pregnancy due to high risk of fetal malformations and miscarriage.
Patients with active gastrointestinal perforation or fistulas.
Severe uncontrolled hypertension despite antihypertensive therapy.
Concurrent use with drugs contraindicated due to potential severe drug interactions that cannot be managed.
Patients with significant bleeding events or bleeding disorders that increase hemorrhage risk.
Breastfeeding mothers due to potential drug secretion and risk to infant.
Known severe hepatic impairment without appropriate monitoring and dose adjustment.
Patients with recent major surgery where impaired wound healing could pose significant risks.
Any condition where the risks of axitinib outweigh the potential benefits as judged by the healthcare provider.

Drug Interactions

Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) increase axitinib plasma concentration, requiring dose adjustment.
Strong CYP3A4 inducers (e.g., rifampin, phenytoin) decrease axitinib exposure, potentially reducing efficacy.
Grapefruit and grapefruit juice inhibit CYP3A4 and may elevate axitinib levels, increasing toxicity risk; avoid consumption.
Concurrent use with anticoagulants or antiplatelet drugs may enhance bleeding risk.
Combination with other antihypertensive agents may require blood pressure dose monitoring due to additive effects.
Drugs that prolong QT interval should be used cautiously due to potential cardiac risks.
Concomitant use of immunosuppressive agents may alter immune response and toxicity profile.
Medications affecting UGT1A1 or minor CYP enzymes may have variable impact on axitinib metabolism.
Herbal supplements such as St. John's Wort may induce CYP3A4 and reduce axitinib efficacy.
No clinically significant interaction with alcohol has been reported, but alcohol may exacerbate side effects.
Interactions with vitamins or over-the-counter supplements have not been well characterized; caution advised.
Co-administration with other VEGFR or multikinase inhibitors increases risk of overlapping toxicities.
Potential interaction with P-glycoprotein substrates; monitoring recommended.
Caution with strong CYP inhibitors may necessitate axitinib dose adjustment and close monitoring.
Regular review of patient medication list is important to identify and manage possible interactions.

Preparations Of The Drug

Inlyta oral tablets available in 1 mg strength for flexible dose titration.
3 mg oral tablets allowing intermediate dosing options.
5 mg oral tablets, the standard starting dose strength for most patients.
7 mg oral tablets provided for dose escalation when clinically appropriate.
Immediate-release oral tablet formulations designed for twice-daily dosing.
Tablets supplied in blister packs or bottles with clear labeling for dosing schedules.
Storage recommendations include keeping tablets at room temperature away from moisture and heat.
Packaging supports patient adherence with adequate supply for dosing intervals.
Instructions to swallow tablets whole without crushing or chewing to maintain bioavailability.
No injectable or alternative solid dosage forms currently marketed under Inlyta brand.
Manufactured under strict quality controls to ensure potency and stability.
Each preparation is scored to aid in dose modification if clinically required.
Packaging includes comprehensive patient information leaflets and safety warnings.
Product supplied with dosing calendars and educational materials for patient support.
Desiccant packs included to preserve tablet integrity during storage.