Inrebic

Required Concomitant Medications

During treatment with INREBIC, all patients should receive prophylaxis with thiamine 100 mg orally daily [see Dosage and Administration (2.7) and Warnings and Precautions (5.1)].

Recommended Dosage

Conduct baseline testing of thiamine (Vitamin B1) levels prior to initiation of INREBIC [see Dosage and Administration (2.7), Warnings and Precautions (5.1)].

The recommended dosage of INREBIC is 400 mg taken orally once daily for patients with a baseline platelet count of greater than or equal to 50 × 109/L.

INREBIC may be taken with or without food. Administration with a high fat meal may reduce the incidence of nausea and vomiting.

Modify the dose for patients using concomitant strong CYP3A4 inhibitors, and in patients with severe renal impairment (creatinine clearance (CLcr) 15 mL/min to 29 mL/min) [see Dosage and Administration (2.4, 2.5)].

If a dose of INREBIC is missed, the next scheduled dose should be taken the following day.

Patients that are on treatment with ruxolitinib before the initiation of INREBIC must taper and discontinue according to the ruxolitinib prescribing information.

Monitoring for Safety

Obtain the following blood tests prior to starting treatment with INREBIC, periodically during treatment, and as clinically indicated [see Warnings and Precautions (5.1, 5.2, 5.4, 5.5)]:

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Thiamine (Vitamin B1) level

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Complete blood count with platelets

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Creatinine and BUN

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Hepatic panel

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Amylase and lipase

Dose Modifications with Concomitant Use of Strong CYP3A4 Inhibitors

Reduce INREBIC dose when administering with strong CYP3A4 inhibitors to 200 mg once daily.

In cases where coadministration with a strong CYP3A4 inhibitor is discontinued, INREBIC dosage should be increased to 300 mg once daily during the first two weeks after discontinuation of the CYP3A4 inhibitor, and then to 400 mg once daily thereafter as tolerated [see Drug Interactions (7.1)].

Dose Modifications for Severe Renal Impairment

Reduce INREBIC dose to 200 mg once daily in patients with severe renal impairment (creatinine clearance (CLcr) 15 mL/min to 29 mL/min as estimated by Cockcroft-Gault (C-G) equation).

Dose Modifications for Adverse Reactions

Modify dose for hematologic and nonhematologic adverse reactions per Table 1 and Table 2. Discontinue INREBIC in patients unable to tolerate a dose of 200 mg daily. See Warnings and Precautions for other mitigating strategies.

Consider dose reductions for patients who become transfusion-dependent during treatment with INREBIC.

Management of Thiamine Levels and Wernicke's Encephalopathy (WE)

Assess thiamine levels and nutritional status prior to starting INREBIC. Do not start INREBIC in patients with thiamine deficiency. However, if thiamine levels are low, replete thiamine prior to starting treatment. While on INREBIC treatment all patients should receive prophylaxis with daily 100 mg oral thiamine and should have thiamine levels assessed as clinically indicated. If Wernicke's encephalopathy is suspected, immediately discontinue treatment with INREBIC and initiate parenteral thiamine treatment. Monitor until symptoms resolve or improve and thiamine levels normalize [see Warnings and Precautions (5.1) and Adverse Reactions (6.1)].

Pregnancy

Lactation

Pediatric Use

The safety and effectiveness of INREBIC in pediatric patients have not been established.

Geriatric Use

Of the total number of patients with myelofibrosis who received an INREBIC dose of 400 mg in the clinical studies, 47.3% were greater than 65 years of age and 12.3% were greater than 75 years of age. No overall differences in safety or effectiveness of INREBIC were observed between these patients and younger patients.

Renal Impairment

Reduce INREBIC dose when administered to patients with severe renal impairment (CLcr 15 mL/min to 29 mL/min by Cockcroft-Gault) [see Dosage and Administration (2.5) and Clinical Pharmacology (12.3)]. No modification of the starting dose is recommended for patients with mild to moderate renal impairment (CLcr 30 mL/min to 89 mL/min by Cockcroft-Gault). Due to potential increase of exposure, patients with preexisting moderate renal impairment require more intensive safety monitoring, and if necessary, dose modifications based on adverse reactions [see Dosage and Administration (2.6)].

Encephalopathy, Including Wernicke's

Serious and fatal encephalopathy, including Wernicke's encephalopathy, has occurred in INREBIC-treated patients. Serious cases were reported in 1.3% (8/608) of patients treated with INREBIC in clinical trials and 0.16% (1/608) of cases were fatal.

Wernicke's encephalopathy is a neurologic emergency resulting from thiamine (Vitamin B1) deficiency. Signs and symptoms of Wernicke's encephalopathy may include ataxia, mental status changes, and ophthalmoplegia (e.g., nystagmus, diplopia). Any change in mental status, confusion, or memory impairment should raise concern for potential encephalopathy, including Wernicke's, and prompt a full evaluation including a neurologic examination, assessment of thiamine levels, and imaging. Assess thiamine levels in all patients prior to starting INREBIC. Do not start INREBIC in patients with thiamine deficiency. However, if thiamine levels are low, replete thiamine prior to starting treatment. While on treatment all patients should receive prophylaxis with oral thiamine and should have thiamine levels assessed as clinically indicated. If encephalopathy is suspected, immediately discontinue INREBIC and initiate parenteral thiamine. Monitor until symptoms resolve or improve and thiamine levels normalize [see Dosage and Administration (2.7) and Adverse Reactions (6.1)].

Anemia and Thrombocytopenia

Treatment with INREBIC can cause anemia and thrombocytopenia.

Gastrointestinal Toxicity

Gastrointestinal toxicities are the most frequent adverse reactions in INREBIC-treated patients. During the randomized treatment period, diarrhea occurred in 66% of patients, nausea in 62% of patients, and vomiting in 39% of patients. Grade 3 diarrhea and vomiting occurred in 5% and 3.1% of patients, respectively. The median time to onset of any grade nausea, vomiting, and diarrhea was 1 day, with 75% of cases occurring within 2 weeks of treatment.

Consider providing appropriate prophylactic antiemetic therapy (e.g., 5-HT3 receptor antagonists) during INREBIC treatment. Treat diarrhea with antidiarrheal medications promptly at the first onset of symptoms. For Grade 3 or higher nausea, vomiting, or diarrhea not responsive to supportive measures within 48 hours, interrupt INREBIC until resolved to Grade 1 or less or baseline. Restart dose at 100 mg daily below the last given dose [see Dosage and Administration (2.6 )]. Monitor thiamine levels and replete as needed.

Hepatic Toxicity

Elevations of ALT and AST (all grades) during the randomized treatment period occurred in 43% and 40%, respectively, with Grade 3 or 4 in 1% and 0%, respectively, of INREBIC-treated patients. The median time to onset of any grade transaminase elevation was approximately 1 month, with 75% of cases occurring within 3 months.

Monitor hepatic function at baseline, periodically during treatment, and as clinically indicated. For Grade 3 or higher ALT and/or AST elevations (greater than 5 × ULN), interrupt INREBIC dose until resolved to Grade 1 or less or to baseline. Restart dose at 100 mg daily below the last given dose. If reoccurrence of a Grade 3 or higher elevation of ALT/AST, discontinue treatment with INREBIC [see Dosage and Administration (2.6)].

Amylase and Lipase Elevation

Grade 3 or higher amylase and/or lipase elevations developed in 2% and 10%, respectively, of INREBIC-treated patients. The median time to onset of any grade amylase or lipase elevation was 15 days, with 75% of cases occurring within 1 month of starting treatment. One patient developed pancreatitis in the fedratinib clinical development program (n=608) and pancreatitis resolved with treatment discontinuation.

Monitor amylase and lipase at baseline, periodically during treatment, and as clinically indicated. For Grade 3 or higher amylase and/or lipase elevations, interrupt INREBIC until resolved to Grade 1 or less or to baseline. Restart dose at 100 mg daily below the last given dose [see Dosage and Administration (2.6)].

Major Adverse Cardiac Events (MACE)

Another Janus Kinase (JAK)-inhibitor has increased the risk of MACE, including cardiovascular death, myocardial infarction, and stroke (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which INREBIC is not indicated.

Consider the benefits and risks for the individual patient prior to initiating or continuing therapy with INREBIC, particularly in patients who are current or past smokers and patients with other cardiovascular risk factors. Patients should be informed about the symptoms of serious cardiovascular events and the steps to take if they occur.

Thrombosis

Another JAK-inhibitor has increased the risk of thrombosis, including deep venous thrombosis, pulmonary embolism, and arterial thrombosis (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which INREBIC is not indicated. In patients with MF treated with INREBIC in clinical trials, the rates of thromboembolic events were similar in INREBIC and placebo treated patients.

Promptly evaluate and treat patients with symptoms of thrombosis.

Secondary Malignancies

Another JAK-inhibitor has increased the risk of lymphoma and other malignancies excluding nonmelanoma skin cancer (NMSC) (compared to those treated with TNF blockers) in patients with rheumatoid arthritis, a condition for which INREBIC is not indicated. Patients who are current or past smokers are at additional increased risk.

Consider the benefits and risks for the individual patient prior to initiating or continuing therapy with INREBIC, particularly in patients with a known malignancy (other than a successfully treated NMSC), patients who develop a malignancy, and patients who are current or past smokers.

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.

The data in the WARNINGS AND PRECAUTIONS Section 5.1 Encephalopathy, including Wernicke's, reflect exposure to INREBIC as a single agent in 608 patients who received more than one dose (ranging from 30 mg to 800 mg) in Studies JAKARTA, ARD11936, JAKARTA2, ARD12042, ARD12888, TED12037/TED12015, INT12497, and TES13519, of whom 459 were patients with myelofibrosis, including 97 patients previously treated with ruxolitinib. Among the 608 patients receiving INREBIC, the median drug exposure was 37 weeks and the median number of cycles initiated was 9 cycles. Fifty-nine percent of 608 patients were exposed for 6 months or longer and 39% were exposed for 12 months or longer.

Using the dataset described above, the most common adverse reactions in >20% of patients (N=608) were diarrhea, nausea, anemia, vomiting, fatigue, thrombocytopenia, and constipation.

Effect of Other Drugs on INREBIC

Effect of INREBIC on Other Drugs

Mechanism of Action

Fedratinib is an oral kinase inhibitor with activity against wild type and mutationally activated Janus Associated Kinase 2 (JAK2) and FMS-like tyrosine kinase 3 (FLT3). Fedratinib is a JAK2-selective inhibitor with higher inhibitory activity for JAK2 over family members JAK1, JAK3 and TYK2. Abnormal activation of JAK2 is associated with myeloproliferative neoplasms (MPNs), including myelofibrosis and polycythemia vera. In cell models expressing mutationally active JAK2V617F or FLT3ITD, fedratinib reduced phosphorylation of signal transducer and activator of transcription (STAT3/5) proteins, inhibited cell proliferation, and induced apoptotic cell death. In mouse models of JAK2V617F-driven myeloproliferative disease, fedratinib blocked phosphorylation of STAT3/5, and improved survival, white blood cell counts, hematocrit, splenomegaly, and fibrosis.

Pharmacodynamics

Fedratinib inhibited cytokine-induced STAT3 phosphorylation in whole blood from patients with myelofibrosis. The inhibition of STAT3 phosphorylation was maximal approximately 2 hours after the first dose, with values returning to near baseline at 24 hours. After daily administration of fedratinib, levels of inhibition at steady state PK were similar to the maximal inhibition reached after the first dose of 300 (0.75 times the recommended dose), 400 or 500 mg (1.25 times the recommended dose) of fedratinib.

Pharmacokinetics

INREBIC at 300 mg to 500 mg once daily (0.75 to 1.25 times the recommended dose) results in a dose proportional increase in geometric mean fedratinib peak concentrations (Cmax) and the area under the plasma concentration time curve over the dosing interval (AUCtau). The mean steady state levels are achieved within 15 days of daily dosing. The mean accumulation ratio ranged between 3- to 4-fold.

At the dose of 400 mg once daily, the geometric mean (coefficient of variation, %CV) fedratinib Cmax is 1804 ng/mL (49%) and AUCtau is 26870 ng.hr/mL (43%) in patients with myelofibrosis.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Fedratinib was not carcinogenic in the 6-month Tg.rasH2 transgenic mouse model.

Fedratinib was not mutagenic in a bacterial mutagenicity assay (Ames test) or clastogenic in in vitro chromosomal aberration assay (Chinese hamster ovary cells) or in vivo in a micronucleus test in rats.

In a fertility study in rats, fedratinib was administered for at least 70 days (males) and 14 days (females) prior to cohabitation and up to the implantation day (gestation day 7). Fedratinib had no effect on the estrous cycle parameters, mating performance, fertility, pregnancy rate or reproductive parameters in male or female rats at doses up to 30 mg/kg. The exposure (AUC) at the dose of 30 mg/kg/day is approximately 0.10 to 0.13 times the clinical exposure at the recommended daily dose.

Animal Toxicology and/or Pharmacology

The JAK/STAT pathway has been implicated in bone formation and metabolism, and its inhibition may cause bone abnormalities, e.g., in developing bone. There is currently no evidence of bone abnormalities in patients who received INREBIC.

JAKARTA

JAKARTA (NCT01437787) was a double-blind, randomized, placebo-controlled trial in patients with intermediate-2 or high-risk myelofibrosis, post-polycythemia vera myelofibrosis or post-essential thrombocythemia myelofibrosis with splenomegaly. A total of 289 patients were randomized to receive either INREBIC 500 mg (N=97), 400 mg (n=96) or placebo (n=96) once daily for at least 6 cycles. The median age was 65 years (range 27 to 86 years), 47% of patients were older than 65 years and 59% were male. Sixty-four percent (64%) of patients had primary MF, 26% had post-polycythemia vera MF, and 10% had post-essential thrombocythemia MF. Fifty-two percent (52%) of patients had intermediate-2 risk, and 48% had high-risk disease. The median baseline hemoglobin level was 10.2 g/dL. The median baseline platelet count was 214 × 109/L; 16% of patients had a platelet count <100 × 109/L and 84% of patients had a platelet count ≥100 × 109/L. Patients had a baseline median palpable spleen length of 15 cm. Patients had a baseline median spleen volume as measured by magnetic resonance imaging (MRI) or computed tomography (CT) of 2568 mL (range of 316 to 8244 mL) (the upper limit of normal is approximately 300 mL). Patients underwent MRI or CT spleen volume assessment (after the third and sixth cycle) with a follow-up scan 4 weeks after Cycle 6.

The efficacy of INREBIC in the treatment of patients with primary or secondary myelofibrosis was established based upon the proportion of patients achieving greater than or equal to a 35% reduction from baseline in spleen volume at the End of Cycle 6 as measured by MRI or CT with a follow-up scan 4 weeks later.

Efficacy analyses are presented in Table 5.

Figure 1 shows the percent change in spleen volume from baseline for patients who have an evaluable MRI/CT at the End of Cycle 6.

Figure 1: Percent Change in Spleen Volume from Baseline at the End of Cycle 6 for Each Patient in the Phase 3 Study, JAKARTA

N*: Subjects with available percent change in spleen volume at EOC6.

Based on Kaplan-Meier estimates, the median duration of spleen response was 18.2 months for the INREBIC 400 mg group.

Additional outcomes included the proportion of patients with a 50% or greater reduction in Total Symptom Score from baseline to the End of Cycle 6 as measured by the modified Myelofibrosis Symptom Assessment Form (MFSAF) v2.0 diary.

The modified MFSAF v2.0 is a patient diary capturing the 6 core symptoms of MF: night sweats, itching, abdominal discomfort, early satiety, pain under ribs on left side, and bone or muscle pain. The modified MFSAF diary was completed daily during the week prior to Day 1 of each treatment cycle, and at the End of Cycle 6. Symptom scores ranged from 0 ("absent") to 10 ("worst imaginable"). These scores were added to create the Total Symptom Score, which has a maximum score of 60. At baseline, the mean Total Symptom Score was 17.95 in the 400 mg group and 15.45 in the placebo group.

The proportion of patients with a 50% or greater reduction in Total Symptom Score was 40% in the INREBIC 400 mg group and 9% in the placebo group (Table 6). Results are excluded for 22 patients: 6 patients with a baseline Total Symptom Score of zero (2 in the INREBIC 400 mg group and 4 in the placebo group) and 16 patients with missing baseline (5 in the INREBIC 400 mg group and 11 in the placebo group).

Figure 2 shows the percent change in Total Symptom Score from baseline at the End of Cycle 6 for each patient.

Figure 2: Percent Change from Baseline in Total Symptom Score at the End of Cycle 6 for Each Patient in the Phase 3 Study, JAKARTA

N*: Subjects with available percent change in Total Symptom Score at EOC6.

Figure 3 displays the proportion of patients with at least a 50% improvement in each of the individual symptoms that comprised the Total Symptom Score indicating that all 6 of the symptoms contributed to the higher Total Symptom Score response rate in the group treated with INREBIC.

Figure 3: Proportion of Patients Achieving 50% or Greater Reduction in Individual Symptom Scores at the End of Cycle 6 with Nonzero Baseline Scores

How Supplied

INREBIC (fedratinib) 100 mg capsules: Reddish brown, opaque, size 0 capsule, printed with "FEDR 100 mg" in white ink.

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Bottles of 120 capsules (NDC 59572-720-12)

Storage

Store below 30°C (86°F).