Common side effects of Selinexor include hematological toxicity, gastrointestinal reactions, and systemic symptoms, which require dosage adjustments or symptomatic treatment based on specific symptoms to alleviate. The following will explain the classification of side effects and corresponding mitigation methods.

1. Hematological toxicity

(1) Thrombocytopenia: The incidence is high, and regular monitoring of platelet count is necessary. If grade 3-4 thrombocytopenia occurs, treatment should be interrupted until it returns to ≤ grade 1, and subsequent treatment should be restarted at the original dose or at a reduced dose.

(2) Neutropenia: may increase the risk of infection. When grade 3-4 neutropenia accompanied by fever occurs, medication should be suspended. After recovery, granulocyte colony-stimulating factor (G-CSF) support may be considered.

(3) Anemia: For moderate to severe anemia, it is necessary to evaluate whether blood transfusion or erythropoietin treatment is needed. For persistent anemia, dosage adjustment should be considered.

2. Gastrointestinal reactions

(1) Nausea/vomiting: Prophylactic use of 5-HT3 receptor antagonists (such as ondansetron) in combination with dexamethasone. If grade 3-4 vomiting occurs, medication should be suspended until improvement occurs, and the dose can be reduced and restarted later.

(2) Diarrhea: Mild to moderate diarrhea can be controlled with loperamide, while severe diarrhea requires temporary cessation of treatment and correction of electrolyte imbalance.

(3) Decreased appetite: It is recommended to eat small meals frequently and receive nutritional support. Continuous weight loss requires an assessment of whether dosage adjustment is necessary.

3. Systemic symptoms

(1) Fatigue: graded management, level 2 fatigue requires assessment of comorbidities, and level 3 or above requires treatment to be suspended until recovery to ≤ level 1.

(2) Hyponatremia: Regularly monitor electrolytes. If symptomatic hyponatremia occurs, medication should be suspended and sodium salts should be supplemented.

4. Other adverse reactions

(1) Infection risk: Immunosuppression may increase the likelihood of opportunistic infections, and fever symptoms should be monitored. Antibiotics should be used preventively if necessary.

(2) Neurological symptoms such as dizziness and blurred consciousness need to be evaluated for their association with hyponatremia, and in severe cases, medication should be discontinued.

5. General Principles of Mitigation Methods

(1) Dose adjustment: Adopt a three-level dose adjustment strategy based on toxicity grading (such as reducing from 80mg to 60mg or 40mg).

(2) Supporting treatment: including symptomatic treatment such as antiemetic, antidiarrheal, blood transfusion, G-CSF, etc.

(3) Monitoring requirements: Regular monitoring of blood routine, electrolytes, liver function and other indicators before and during treatment.