Fostamatinib

1 INDICATIONS AND USAGE 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.

2 DOSAGE AND ADMINISTRATION 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. Management of some adverse reactions may require dose-interruption, reduction, or discontinuation. A dose reduction schedule is provided in Table 1, based on daily dose. For example, if a patient is on the maximum dose at the time of an adverse reaction, the first dose reduction would be from 300 mg/day to 200 mg/day. Table 1: Dose Reduction Schedule Daily Dose Administered as: AM PM 300 mg/day 150 mg 150 mg 200 mg/day 100 mg 100 mg 150 mg/day 150 mg Once daily TAVALISSE should be taken in the morning. --- 100 mg/day If further dose reduction below 100 mg/day is required, discontinue TAVALISSE. 100 mg --- The recommended dose modifications for adverse reactions are provided in Table 2. Table 2: Recommended Dose Modifications and Management for Specific Adverse Reactions Adverse Reaction Recommended Action ALT = alanine aminotransferase; AST = aspartate aminotransferase; BP = blood pressure; BL = bilirubin; ULN = upper limit of normal; LFT = liver function tests (AST, ALT, total BL with fractionation if elevated, alkaline phosphatase); AST/ALT = AST or ALT Hypertension Stage 1: systolic between 130-139 or diastolic between 80-89 mmHg Initiate or increase dosage of antihypertensive medication for patients with increased cardiovascular risk, and adjust as needed until BP is controlled. If the BP target is not met after 8 weeks, reduce TAVALISSE to next lower daily dose (refer to Table 1). Stage 2: systolic at least 140 or diastolic at least 90 mmHg Initiate or increase dosage of antihypertensive medication, and adjust as needed until BP is controlled. If BP remains 140/90 mmHg or higher for more than 8 weeks, reduce TAVALISSE to next lower daily dose (refer to Table 1). If BP remains 160/100 mmHg or higher for more than 4 weeks despite aggressive antihypertensive therapy, interrupt or discontinue TAVALISSE. Hypertensive crisis: systolic over 180 and/or diastolic over 120 mmHg Interrupt or discontinue TAVALISSE. Initiate or increase dosage of antihypertensive medication, and adjust as needed until BP is controlled. If BP returns to less than the target BP, resume TAVALISSE at same daily dose. If repeat BP is 160/100 mmHg or higher for more than 4 weeks despite aggressive antihypertensive treatment, discontinue TAVALISSE. Hepatotoxicity AST/ALT is 3 × ULN or higher and less than 5 × ULN If patient is symptomatic (e.g., nausea, vomiting, abdominal pain): Interrupt TAVALISSE. Recheck LFTs every 72 hours until ALT/AST values are no longer elevated (below 1.5 × ULN) and total BL remains less than 2 × ULN. Resume TAVALISSE at next lower daily dose (refer to Table 1). If patient is asymptomatic: Recheck LFTs every 72 hours until ALT/AST are below 1.5 × ULN) and total BL remains less than 2 × ULN. Consider interruption or dose reduction of TAVALISSE if ALT/AST and TBL remain in this category (AST/ALT is 3 to 5 × ULN; and total BL remains less than 2 × ULN) If interrupted, resume TAVALISSE at next lower daily dose (refer to Table 1) when ALT/AST are no longer elevated (below 1.5 × ULN) and total BL remains less than 2 × ULN. AST/ALT is 5 × ULN or higher and total BL is less than 2 × ULN Interrupt TAVALISSE. Recheck LFTs every 72 hours: If AST and ALT decrease, recheck until ALT and AST are no longer elevated (below 1.5 × ULN) and total BL remains less than 2 × ULN; resume TAVALISSE at next lower daily dose (refer to Table 1). If AST/ALT persist at 5 × ULN or higher for 2 weeks or more, discontinue TAVALISSE. AST/ALT is 3 × ULN or higher and total BL is greater than 2 × ULN Discontinue TAVALISSE. Elevated unconjugated (indirect) BL in absence of other LFT abnormalities Continue TAVALISSE with frequent monitoring since isolated increase in unconjugated (indirect) BL may be due to UGT1A1 inhibition Diarrhea Diarrhea Manage diarrhea using supportive measures (e.g., dietary changes, hydration and/or antidiarrheal medication) early after the onset until symptom(s) have resolved. If symptom(s) become severe (Grade 3 or above), temporarily interrupt TAVALISSE. If diarrhea improves to mild (Grade 1), resume TAVALISSE at the next lower daily dose (refer to Table 1). Neutropenia Neutropenia If absolute neutrophil count decreases (ANC less than 1.0 × 10 9 /L) and remains low after 72 hours, temporarily interrupt TAVALISSE until resolved (ANC greater than 1.5 × 10 9 /L). Resume TAVALISSE at the next lower daily dose (refer to Table 1). 2.4 Dose Modification for Drug Interactions Concomitant use with a strong CYP3A4 inhibitor increases exposure to R406 (the major active metabolite). Monitor for toxicities of TAVALISSE that may require TAVALISSE dose modifications (see Table 1 ) when given concurrently with a strong CYP3A4 inhibitor [see Drug Interactions (7.1) ] . 2.5 Discontinuation Discontinue TAVALISSE after 12 weeks of treatment if the platelet count does not increase to a level sufficient to avoid clinically important bleeding [see Clinical Studies (14) ] .

6 ADVERSE REACTIONS 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. In the placebo controlled studies, the median duration of TAVALISSE exposure in these studies was 86 days (range 8 to 183) [see Clinical Studies (14) for additional details for patients on TAVALISSE ] . In the ITP double-blind studies, serious adverse drug reactions were febrile neutropenia, diarrhea, pneumonia, and hypertensive crisis, which each occurred in 1% of patients receiving TAVALISSE. In addition, severe adverse reactions observed in patients receiving TAVALISSE included dyspnea and hypertension (both 2%); and neutropenia, arthralgia, chest pain, diarrhea, dizziness, nephrolithiasis, pain in extremity, toothache, syncope and hypoxia (all 1%) [see Warnings and Precautions (5.1) ] . Table 3 presents the common adverse reactions from these studies. Table 3: Incidence of Common (≥ 5%) Adverse Reactions from Double-Blind Clinical Studies (FIT 1 and FIT 2) Adverse Reaction TAVALISSE (N=102) Placebo (N=48) Mild % Moderate % Severe % TOTAL % Mild % Moderate % Severe % TOTAL % ALT = Alanine aminotransferase AST = Aspartate aminotransferase Note: Common adverse reactions defined as all adverse reactions occurring at a rate of ≥ 5% of patients in the TAVALISSE group and greater than placebo rate. Diarrhea Includes diarrhea and frequent bowel movement. 21 10 1 31 13 2 0 15 Hypertension Includes hypertension, blood pressure (BP) increased, BP diastolic abnormal, and BP diastolic increased. 17 9 2 28 10 0 2 13 Nausea 16 3 0 19 8 0 0 8 Dizziness 8 2 1 11 6 2 0 8 ALT increased 5 6 0 11 0 0 0 0 AST increased 5 4 0 9 0 0 0 0 Respiratory infection Includes upper respiratory tract infection, respiratory tract infection, lower respiratory tract infection, and viral upper respiratory tract infection. 7 4 0 11 6 0 0 6 Rash Includes rash, rash erythematous and rash macular. 8 1 0 9 2 0 0 2 Abdominal pain Includes abdominal pain, and abdominal pain upper. 5 1 0 6 2 0 0 2 Fatigue 4 2 0 6 0 2 0 2 Chest pain 2 3 1 6 2 0 0 2 Neutropenia Includes neutropenia and neutrophil count decreased. 3 2 1 6 0 0 0 0 Table 4: Elevations in Hepatic Transaminases During Placebo-Controlled Clinical Studies Enzyme Maximum Level of Elevation Number of Patients (%) TAVALISSE (N=102) Placebo (N=48) Alanine aminotransferase (ALT) and/or Aspartate aminotransferase (AST) >3 and ≤5 × ULN 3 (3) 0 >5 and ≤10 × ULN 5 (5) 0 ≥10 × ULN 1 (1) 0

12.3 Pharmacokinetics 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. R406 exposure is approximately dose proportional up to 200 mg twice daily (1.3 times the 150 mg dosage). R406 accumulates approximately 2- to 3-fold upon twice daily dosing at 100–160 mg (0.67 to 1.06 times the 150 mg dosage). Absorption After oral administration of TAVALISSE, the absolute bioavailability of R406 was 55%. The median t max of R406 is approximately 1.5 hours (range: 1 to 4 hours). Negligible levels of fostamatinib were found in plasma. Effect of Food Administration of TAVALISSE with a high-calorie, high-fat meal (deriving approximately 150, 250, and 500–600 calories from protein, carbohydrate, and fat, respectively) increased R406 AUC by 23% and C max by 15% [see Dosage and Administration (2.1) ] . Distribution In in vitro studies, the R406 is 98.3% protein bound in human plasma. The red blood cell to plasma concentration ratio is approximately 2.6. The mean (± SD) volume of distribution at steady-state of R406 is 256 (± 92) L. Elimination The mean (± SD) terminal half-life of R406 is approximately 15 (± 4.3) hours. Metabolism TAVALISSE is metabolized in the gut by alkaline phosphatase to the major active metabolite, R406. R406 is extensively metabolized, primarily through pathways of CYP450-mediated oxidation (by CYP3A4) and glucuronidation (by UDP glucuronosyltransferase [UGT]1A9). R406 is the predominant moiety in the systemic circulation, and there was minimal exposure to any R406 metabolites. Excretion Following an oral dose of TAVALISSE, approximately 80% of the R406 metabolite is excreted in feces with approximately 20% excreted in the urine. The major component excreted in urine was R406 N-glucuronide. The major components excreted in feces were R406, O -desmethyl R406 and a metabolite produced by gut bacteria from the O -desmethyl metabolite of R406. Specific Populations Population pharmacokinetics analyses indicate TAVALISSE is not altered based on age, sex, race/ethnicity. In addition, the pharmacokinetics of TAVALISSE is not altered in patients with renal impairment (creatinine clearance [CLcr] ≥ 30 to < 50 mL/min, estimated by Cockcroft Gault equation and end stage renal disease requiring dialysis), or hepatic impairment (Child-Pugh Class A, B and C). Drug Interaction Studies Clinical Pharmacology Studies No significant interactions were seen with concomitant use of TAVALISSE with the following drugs: methotrexate (OAT1/3 transporters), midazolam (CYP3A4 substrate), microgynon (ethinyl estradiol and levonorgestrel), warfarin, pioglitazone (CYP2C8 substrate) and ranitidine (H2-antagonist that increases gastric pH). Effect of Other Drugs on TAVALISSE Strong CYP3A4 inhibitor : Concomitant use of ketoconazole (200 mg twice daily for 3.5 days) with a single dose of 80 mg TAVALISSE (0.53 times the 150 mg dosage) increased R406 AUC by 102% and C max by 37%. Moderate CYP3A4 Inhibitor : Concomitant use of verapamil (80 mg three times daily for 4 days) with a single dose of 150 mg TAVALISSE increased R406 AUC by 39% and C max by 6% . CYP3A4 inducer : Concomitant use of rifampicin (600 mg once daily for 8 days) with a single dose of 150 mg TAVALISSE decreased R406 AUC by 75% and C max by 59% . Effect of TAVALISSE on Other Drugs CYP3A4 substrate: Concomitant use of simvastatin (single dose 40 mg) with 100 mg twice daily TAVALISSE increased simvastatin AUC by 64% and C max by 113% and simvastatin acid AUC by 64% and C max by 83%. BCRP substrate : Concomitant use of rosuvastatin (single dose 20 mg) with 100 mg twice daily TAVALISSE increased rosuvastatin AUC by 95% and C max by 88%. P-gp substrate : Concomitant use of digoxin (0.25 mg once daily) with 100 mg twice daily TAVALISSE increased digoxin AUC by 37% and C max by 70% . In Vitro Studies TAVALISSE is an inhibitor of the human P-gp efflux transporter in vitro. CYP3A4 and UGT1A9 are involved in the metabolism of R406. R406 is a substrate of P-gp but not of other major transporters (OAT1/3, OCT2, OATP1B1/3, MRP2, and BCRP). R406 can inhibit CYP3A4 and BCRP, and can induce CYP2C8 activity. R406 is an inhibitor of UGT1A1. Inhibition of UGT1A1 may result in increased unconjugated bilirubin in the absence of other LFT abnormalities.