Fostamatinib

Fostamatinib is a tyrosine kinase inhibitor with demonstrated activity against spleen tyrosine kinase (SYK). The major metabolite of fostamatinib, R406, inhibits signal transduction of Fc-activating receptors and B-cell receptor.

• TAVALISSE is indicated for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment. TAVALISSE is a kinase inhibitor indicated for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment.

• None. None.contraindicated

Initiate TAVALISSE at 100 mg orally twice daily with or without food. After 4 weeks, increase to 150 mg twice daily, if needed, to achieve platelet counts of at least 50 × 10 9 /L as necessary to reduce the risk of bleeding. ( 2.1 ) Manage adverse reactions using dose reduction, interruption of treatment, or discontinuation. ( 2.3 ) Discontinue TAVALISSE after 12 weeks of treatment if the platelet count does not increase to a level sufficient to avoid clinically important bleeding. ( 2.5 ) 2.1 Recommended Dosage Initiate TAVALISSE at a dose of 100 mg taken orally twice daily. After a month, if platelet count has not increased to at least 50 × 10 9 /L, increase TAVALISSE dose to 150 mg twice daily. Use the lowest dose of TAVALISSE to achieve and maintain a platelet count at least 50 × 10 9 /L as necessary to reduce the risk of bleeding. TAVALISSE may be taken with or without food. In the case of a missed dose of TAVALISSE, instruct patients to take their next dose at its regularly scheduled time. 2.2 Monitoring After obtaining baseline assessments: Monitor CBCs, including platelet counts, monthly until a stable platelet count (at least 50 × 10 9 /L) is achieved. Thereafter, continue to monitor CBCs, including neutrophils, regularly. Monitor liver function tests (LFTs) (e.g., ALT, AST, and bilirubin) monthly. Monitor blood pressure every 2 weeks until establishment of a stable dose, then monthly thereafter. 2.3 Dose Modification for Adverse Reactions TAVALISSE dose modification is recommended based on individual safety and tolerability.

Hypertension: Monitor blood pressure every 2 weeks until stable, then monthly. Manage hypertension using standard antihypertensive treatment and, if needed, interrupt, reduce or discontinue TAVALISSE. ( 5.1 ) Hepatotoxicity: Monitor LFTs monthly. If LFT levels are elevated, interrupt, reduce or discontinue TAVALISSE. ( 5.2 ) Diarrhea: Manage diarrhea with supportive measures. If diarrhea becomes severe, interrupt, reduce or discontinue TAVALISSE. ( 5.3 ) Neutropenia: Monitor ANC monthly, and for infection. If neutrophil count decreases below 1.0 × 10 9 /L, interrupt, reduce or discontinue TAVALISSE. ( 5.4 ) Embryo-Fetal Toxicity: TAVALISSE can cause fetal harm. Advise patients of potential risk to a fetus and to use effective contraception. ( 5.5 ) 5.1 Hypertension Hypertension can occur with TAVALISSE treatment; hypertensive crisis occurred in 1% of patients. Patients with pre-existing hypertension may be more susceptible to the hypertensive effects of TAVALISSE. Monitor blood pressure every 2 weeks until stable, then monthly and adjust or initiate antihypertensive therapy to ensure maintenance of blood pressure control during TAVALISSE therapy. If increased blood pressure persists despite appropriate therapy, TAVALISSE interruption, reduction or discontinuation may be necessary [see Dosage and Administration (2.3) ] . 5.2 Hepatotoxicity Elevated liver function tests (LFTs), mainly ALT and AST, can occur with TAVALISSE.

The following clinically important adverse reactions, that can become serious are described elsewhere in the labeling: Hypertension [ see Warnings and Precautions (5.1) ] Hepatotoxicity [ see Warnings and Precautions (5.2) ] Diarrhea [ see Warnings and Precautions (5.3) ] Neutropenia [ see Warnings and Precautions (5.4) ] The most common adverse reactions (≥5% and more than placebo) are diarrhea, hypertension, nausea, respiratory infection, dizziness, ALT/AST increased, rash, abdominal pain, fatigue, chest pain and neutropenia. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Rigel Pharmaceuticals, Inc. at 1-800-983-1329 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. TAVALISSE was studied in two randomized, double-blind, placebo-controlled trials that were identical in design. The data described below reflect exposure to TAVALISSE in 102 patients with chronic ITP who had received one or more prior ITP treatment(s). Groups were stratified with respect to splenectomy and severity of thrombocytopenia. Patients randomized to the TAVALISSE arm received 100 mg orally twice daily. Based upon platelet count and tolerability, if a patient's platelet count did not increase to at least 50 × 10 9 /L, the TAVALISSE dose could be increased to 150 mg twice daily after one month.

Pregnancy: Advise women of the risk to a fetus. ( 8.1 ) Lactation: Advise women not to breastfeed. ( 8.2 ) 8.1 Pregnancy Risk Summary Based on findings from animal studies and the mechanism of action, TAVALISSE can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1) ]. There are no available data in pregnant women to inform the drug-associated risk. In animal reproduction studies, administration of fostamatinib to pregnant rats and rabbits during organogenesis caused adverse developmental outcomes that were directly attributed to exposure in utero to the major fostamatinib metabolite (R406) at maternal exposures (AUC) as low as 0.3 and 10 times the exposure in patients at the maximum recommended human dose (MRHD), respectively (see Data ). Advise pregnant women of the potential risk to a fetus. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. An estimated background risk of major birth defects and miscarriage for the chronic ITP population is 8% and 4-11%, respectively.

Metabolism

TAVALISSE is a prodrug that is converted in the gut to the major active metabolite, R406. Mean (± standard deviation [SD]) exposure estimates of R406 are 550 (± 270) ng/mL for C max and 7080 (± 2670) ng∙h/mL for AUC.

There is no specific antidote for overdose with TAVALISSE, and the amount of R406 (the pharmacologically active metabolite of fostamatinib) cleared by dialysis is negligible. In the event of an overdose, monitor patient closely for signs and symptoms of adverse reactions, and treat the reactions with supportive care [see Warnings and Precautions (5) ] .

• Apr 17, 2018NDANDA209299Rigel Pharms

1. 1Diarrhoea90114%
2. 2Platelet Count Decreased84613%
3. 3Product Dose Omission Issue73111%
4. 4Off Label Use70711%
5. 5Hospitalisation4406.8%
6. 6Platelet Count3815.8%
7. 7Drug Ineffective3665.6%
8. 8Fatigue3385.2%
9. 9Death3255.0%
10. 10Blood Pressure Increased3235.0%
11. 11Headache2363.6%
12. 12Product Prescribing Issue2183.3%
13. 13Nausea2133.3%
14. 14Dizziness1933.0%
15. 15Hypertension1822.8%

The 10 most recently updated of 67 ClinicalTrials.gov registrations naming Fostamatinib as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• Syk Inhibition in MItigating Lung Allograft Rejection (SIMILAR): A Trial to Evaluate the Safety and Tolerability of Fostamatinib in Lung Transplant Patients With Donor-Specific Antibodies
  Not yet recruiting · Phase 1 · Interventional · 30 enrolled · National Heart, Lung, and Blood Institute (NHLBI)
  NCT06948097updated 2026-06-12
• Study to Evaluate the Safety and Tolerability of Escalating Doses of Fostamatinib in Subjects With Stable Sickle Cell Disease
  Recruiting · Phase 1 · Interventional · 25 enrolled · National Heart, Lung, and Blood Institute (NHLBI)
  NCT05904093updated 2026-05-28
• Perioperative Fostamatinib With Gemcitabine and Nab-paclitaxel in Resectable Pancreatic Cancer
  Recruiting · Phase 1 · Interventional · 36 enrolled · University of California, San Diego
  NCT06639724updated 2026-04-07
• Fostamatinib for Treating Acute Respiratory Distress Syndrome (ARDS) in Hospitalized Adults
  Not yet recruiting · Phase 2 · Interventional · 40 enrolled · Inova Health Care Services
  NCT06564207updated 2026-02-02
• Ruxolitinib Plus Fostamatinib for Steroid Refractory cGvHD
  Recruiting · Phase 1 · Interventional · 30 enrolled · Stefanie Sarantopoulos, MD, PhD.
  NCT06233110updated 2026-01-22
• Using Fostamatinib to Treat Post-Hematopoietic Stem Cell Transplant Immune-mediated Cytopenias
  Terminated · Phase 2 · Interventional · 1 enrolled · National Heart, Lung, and Blood Institute (NHLBI)
  NCT05502783updated 2025-12-05
• Inflammatory Signal Inhibitors for COVID-19 (MATIS)
  Completed · Phase 1 · Phase 2 · Interventional · 185 enrolled · Imperial College London
  NCT04581954updated 2025-11-18
• Extension Study (Extended Access) of Syk-inhibition Using Fostamatinib to Treat Posttransplant Immune-mediated Cytopenias
  Withdrawn · Phase 2 · Interventional · 0 enrolled · National Heart, Lung, and Blood Institute (NHLBI)
  NCT05509582updated 2025-11-10
• A Clinical Study in Patients With Chronic Idiopathic Thrombocytopenic Purpura in R788
  Completed · Phase 3 · Interventional · 34 enrolled · Kissei Pharmaceutical Co., Ltd.
  NCT04132050updated 2025-08-11
• International Sites: Novel Experimental COVID-19 Therapies Affecting Host Response
  Terminated · Phase 2 · Phase 3 · Interventional · 28 enrolled · NEAT ID Foundation
  NCT05593770updated 2025-05-02

Frequently asked questions

How does Fostamatinib work?

Fostamatinib is a tyrosine kinase inhibitor with demonstrated activity against spleen tyrosine kinase (SYK). The major metabolite of fostamatinib, R406, inhibits signal transduction of Fc-activating receptors and B-cell receptor.

What is Fostamatinib used for?

According to FDA labeling, Fostamatinib carries indications including: TAVALISSE is indicated for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment. TAVALISSE is a kinase inhibitor indicated for the treatment of thrombocytopenia in adult patients with chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fostamatinib?

Fostamatinib is classified as Other systemic hemostatics, Adenosine Receptor Antagonists, Tyrosine Kinase Inhibitors, Vasodilation.

What are the brand names for Fostamatinib?

Fostamatinib is marketed under brand names including Tavalisse.

What are the contraindications for Fostamatinib?

Fostamatinib labeling lists contraindications including: None. None.. Always consult the full prescribing information and a clinician.