What is fostatinib? What are its pharmacological effects and therapeutic principles?

Fostamatinib is an oral tyrosine kinase inhibitor (TKI) mainly used to treat chronic immune thrombocytopenia (ITP). It is a prodrug that is metabolized in the body to its active form, R406, which selectively inhibits spleen tyrosine kinase (SYK). SYK plays a key role in the immune system, especially participating in the Fc receptor and B cell receptor signaling pathways, affecting the function of immune cells.

In people with ITP, autoimmune abnormalities in the body cause the immune system to incorrectly recognize and destroy platelets. The main mechanism of action of fostatinib is to inhibit the SYK signaling pathway and block the phagocytosis of platelets by macrophages, thereby reducing platelet destruction and maintaining the number of platelets. In addition, inhibition of SYK can also reduce B cell-mediated autoantibody production, thereby reducing immune consumption of platelets.

The recommended dose of fostatinib is 100 mg twice daily. The dose can be adjusted to 150 mg twice daily based on the patient's platelet level and tolerance. This drug is primarily metabolized by the liver and excreted in bile and urine, so it should be used with caution in patients with impaired liver and kidney function.
In clinical trials, fostatinib has shown good efficacy in patients with refractory ITP, especially those who have failed to respond to corticosteroids or intravenous gamma globulin (IVIG) therapy. However, this drug may cause adverse reactions such as hypertension, diarrhea, abnormal liver function, and neutropenia. Therefore, blood pressure, liver enzyme levels, and routine blood tests need to be monitored regularly during treatment. Overall, fostatinib provides a new treatment option for ITP patients by modulating the immune system and reducing platelet destruction.
Reference: https://www.tavalisse.com/