How long should the sunitinib treatment cycle be considered before stopping the drug?

Sunitinib is a broad-spectrum multi-target tyrosine kinase inhibitor, mainly used for the treatment of malignant diseases such as renal cell carcinoma (RCC), gastrointestinal stromal tumors (GIST) and pancreatic neuroendocrine tumors. The drug blocks tumor angiogenesis and cell proliferation by inhibiting multiple receptors, such as VEGFR, PDGFR, KIT, etc., thereby delaying the course of the disease. The medication cycle and whether to discontinue sunitinib is a highly individualized issue that needs to be comprehensively judged based on multiple factors such as the patient’s disease stage, clinical response, side-effect tolerance, and imaging changes.

In the standard treatment plan, sunitinib often adopts a cyclic administration mode of "4 weeks of medication + 2 weeks of drug off", that is, every 6 weeks is a complete cycle. According to clinical practice, patients need to take it for multiple cycles continuously to observe the efficacy. Usually, imaging or tumor marker evaluation is started after at least 2 to 3 cycles of treatment. If the treatment effect is stable, that is, the disease is well controlled (such as partial remission or stable disease), treatment may be continued for several months or even longer. In some patients with kidney cancer or GIST, sunitinib is used long-term as maintenance therapy until the disease progresses or the side effects are intolerable.

Regarding the timing of drug discontinuation, current international guidelines generally recommend that drug discontinuation be considered under the following circumstances: first, the patient has clear disease progression, and imaging confirms tumor recurrence, metastasis, or enlargement, suggesting the need to change the treatment plan; second, serious adverse reactions occur, such as refractory hypertension, severe cardiotoxicity, uncontrollable bleeding, or liver and kidney failure, etc. At this time, suspension or permanent discontinuation of the drug needs to be considered based on the doctor's evaluation; third, some patients can try to discontinue the drug for observation after long-term disease stabilization, but this strategy requires strict follow-up to catch signs of recurrence in a timely manner.

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