Cabozantinib Capsules: A Multi-Targeted Therapy for Progressive Medullary Thyroid Cancer

　　1.Why Does Medullary Thyroid Cancer Require Targeted Therapy?

　　Medullary thyroid cancer(MTC)originates from the parafollicular C cells of the thyroid gland and represents a relatively rare form of thyroid malignancy.Unlike the more common papillary and follicular thyroid cancers,MTC is insensitive to radioactive iodine therapy.Some patients present with local invasion or distant metastasis at the time of diagnosis.When surgery cannot achieve complete tumor removal or the disease progresses,systemic pharmacotherapy becomes essential,and targeted agents play a central role in disease management.

　　2.Mechanism of Action of Cabozantinib Capsules

　　Cabozantinib is an oral small-molecule multi-target tyrosine kinase inhibitor(TKI)that acts on multiple kinases closely associated with tumor development,including RET,MET,VEGFR-1/2/3,AXL,ROS1,and KIT.These signaling pathways are involved in tumor cell proliferation,angiogenesis,invasion,and metastasis.By simultaneously blocking multiple pathways,cabozantinib suppresses tumor growth and dissemination from several dimensions.This multi-target synergistic mechanism distinguishes it from single-target agents and provides a unique advantage in addressing tumor heterogeneity and drug resistance.

　　3.Clinical Efficacy and Applicable Population

　　Cabozantinib capsules received FDA approval in 2012,becoming the first multi-target kinase inhibitor approved for progressive,metastatic medullary thyroid cancer.Clinical studies have demonstrated that cabozantinib significantly prolongs progression-free survival in eligible MTC patients,offering an important systemic treatment option for those with advanced disease.

　　It is important to note that cabozantinib is not indicated for all types of thyroid cancer.Differentiated thyroid cancers such as papillary and follicular thyroid cancer follow different treatment strategies.Patients should select appropriate treatment plans based on their pathological type and disease stage under professional medical guidance.Treatment outcomes may also be influenced by disease stage,tumor molecular characteristics,overall health status,and prior treatment history.

　　4.Precautions and Common Adverse Reactions

　　The recommended dose of cabozantinib capsules is 140 mg once daily,taken on an empty stomach(avoiding food for at least 2 hours before and 1 hour after dosing).Capsules should be swallowed whole and must not be opened or chewed.Common adverse reactions during treatment include diarrhea,palmar-plantar erythrodysesthesia(hand-foot syndrome),fatigue,decreased appetite,weight loss,and hypertension.Most of these can be managed through dose adjustments or supportive care.

　　Additionally,the capsule and tablet formulations differ in dosage and bioavailability and should not be interchanged without medical supervision.Patients should carefully verify the formulation and specifications when obtaining the medication,strictly follow medical instructions,and undergo regular monitoring of blood pressure,liver function,and renal function during treatment.