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Synribo

Last reviewed on RxList: 1/5/2017
Drug Description

 SYNRIBO®
(omacetaxine mepesuccinate) Injection

DESCRIPTION

SYNRIBO contains the active ingredient omacetaxine mepesuccinate, a cephalotaxine ester. It is a protein synthesis inhibitor. Omacetaxine mepesuccinate is prepared by a semi-synthetic process from cephalotaxine, an extract from the leaves of Cephalotaxus sp. The chemical name of omacetaxine mepesuccinate is cephalotaxine, 4-methyl (2R)-hydroxyl-2-(4-hydroxyl-4-methylpentyl) butanedioate (ester).

Omacetaxine mepesuccinate has the following chemical structure:

SYNRIBO® (omacetaxine mepesuccinate) Structural Formula Illustration

The molecular formula is C29H39NO9 with a molecular weight of 545.6 g/mol. SYNRIBO for Injection is a sterile, preservative-free, white to off-white, lyophilized powder in a single-use vial. Each vial contains 3.5 mg omacetaxine mepesuccinate and mannitol. SYNRIBO is intended for subcutaneous administration after reconstitution with 1.0 mL of 0.9% Sodium Chloride Injection, USP. The pH of the reconstituted solution is between 5.5 and 7.0.

Indications & Dosage

INDICATIONS

SYNRIBO is indicated for the treatment of adult patients with chronic or accelerated phase chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKI).

DOSAGE AND ADMINISTRATION

Induction Schedule

The recommended starting schedule for induction is 1.25 mg/m²administered subcutaneously twice daily for 14 consecutive days every 28 days, over a 28-day cycle. Cycles should be repeated every 28 days until patients achieve a hematologic response.

Maintenance Dosing

The recommended maintenance schedule is 1.25 mg/m²administered subcutaneously twice daily for 7 consecutive days every 28 days, over a 28-day cycle. Treatment should continue as long as patients are clinically benefiting from therapy.

Dose Adjustments And Modifications

Hematologic Toxicity

SYNRIBO treatment cycles may be delayed and/or the number of days of dosing during the cycle reduced for hematologic toxicities (e.g. neutropenia, thrombocytopenia). [see WARNINGS AND PRECAUTIONS]

Complete blood counts (CBCs) should be performed weekly during induction and initial maintenance cycles. After initial maintenance cycles, monitor CBCs every two weeks or as clinically indicated. If a patient experiences Grade 4 neutropenia (absolute neutrophil count (ANC) less than 0.5 x 109/L) or Grade 3 thrombocytopenia (platelet counts less than 50 x 109/L) during a cycle, delay starting the next cycle until ANC is greater than or equal to 1.0 x 109/L and platelet count is greater than or equal to 50 x 109/L. Also, for the next cycle, reduce the number of dosing days by 2 days (e.g. to 12 or 5 days).

Non-Hematologic Toxicity

Manage other clinically significant non-hematologic toxicity symptomatically. Interrupt and/or delay SYNRIBO until toxicity is resolved.

Preparation And Administration Precautions

SYNRIBO should be prepared in a healthcare facility and administered by a healthcare professional. Omacetaxine mepesuccinate is an antineoplastic product. Follow special handling and disposal procedures.

Reconstitute SYNRIBO with one mL of 0.9% Sodium Chloride Injection, USP, prior to subcutaneous injection. After addition of the diluent, gently swirl until a clear solution is obtained. The lyophilized powder should be completely dissolved in less than one minute. The resulting solution will contain 3.5 mg/mL SYNRIBO.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.

Avoid contact with the skin. If SYNRIBO comes into contact with skin, immediately and thoroughly wash affected area with soap and water.

Use SYNRIBO within 12 hours of reconstitution when stored at room temperature and within 24 hours of reconstitution if stored at 2°C to 8°C (36°F to 46°F). Protect reconstituted solution from light. After administration, any unused solution should be discarded properly1.

HOW SUPPLIED

Dosage Forms And Strengths

SYNRIBO for Injection contains 3.5 mg omacetaxine mepesuccinate; as a sterile, preservative-free, white to off-white lyophilized powder in a single-use vial.

SYNRIBO (omacetaxine mepesuccinate) for Injection is supplied in 8 mL clear glass single-use vial in individual cartons. Each vial contains 3.5 mg of SYNRIBO (omacetaxine mepesuccinate) for Injection (NDC 63459-177-14).

Storage And Handling

Store at 20°C to 25°C (68°F to 77°F); excursions permitted from 15°C to 30°C (59°F to 86°F). Until use, keep product in carton to protect from light. Omacetaxine mepesuccinate is an antineoplastic product. Follow special handling and disposal procedures1.

REFERENCES

1. OSHA Hazardous Drugs. OSHA. http://www.osha.gov/SLTC/hazardousdrugs/index.html.

Distributed by: Teva Pharmaceuticals USA, Inc. North Wales, PA 19454. Revised: February 2014.

Side Effects & Drug Interactions

SIDE EFFECTS

The following serious adverse reactions have been associated with SYNRIBO in clinical trials and are discussed in greater detail in other sections of the label.

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 safety data for SYNRIBO are from 3 clinical trials which enrolled a total of 163 adult patients with TKI resistant and/or intolerant chronic phase (N=108) and accelerated phase (N=55) CML. All patients were treated with initial induction therapy consisting of a dose of 1.25 mg/m²administered subcutaneously twice daily for 14 consecutive days every 28 days (induction cycle). Responding patients were then treated with the same dose and a twice daily schedule for 7 consecutive days every 28 days (maintenance cycle).

Clinical Trials Experience

Chronic Phase CML

The median duration of exposure for the 108 patients with chronic phase CML was 7.4 months (range 0 to 43 months). The median total cycles of exposure was 6 (range 1 to 41), and the median total dose delivered during the trials was 131 mg/m²(range 1.2 to 678). Among the patients with chronic phase CML, 87% received 14 days of treatment during cycle 1. By cycles 2 and 3, the percentage of patients receiving 14 days of treatment decreased to 42% and 16% respectively. Of the 91 patients who received at least 2 cycles of treatment, 79 (87%) had at least 1 cycle delay during the trials. The median number of days of cycle delays was greatest for cycle 2 (17 days) and cycle 3 (25 days) when more patients were receiving induction cycles. Adverse reactions were reported for 99% of the patients with chronic phase CML. A total of 18% of patients had adverse reactions leading to withdrawal. The most frequently occurring adverse reactions leading to discontinuation were pancytopenia, thrombocytopenia, and increased alanine aminotransferase (each 2%). A total of 87% of patients reported at least 1 Grade 3 or Grade 4 treatment emergent adverse reactions (Table 1).

Table 1: Adverse Reactions Occurringa in at Least 10% of Patients (Chronic Myeloid Leukemia – Chronic Phase)

Adverse reactions Number (%) of Patients
(N=108)
All reactions Grade 3 or 4 reactions
Patients with at least 1 commonly occurring adverse reaction 107 (99) 94 (87)
Blood and Lymphatic System Disorders
  Thrombocytopenia 82 (76) 73 (68)
  Anemia 66 (61) 39 (36)
  Neutropenia 57 (53) 51 (47)
  Lymphopenia 18 (17) 17 (16)
  Bone Marrow Failure 11 (10) 11 (10)
  Febrile Neutropenia 11 (10) 11 (10)
Gastrointestinal Disorders
  Diarrhea 44 (41) 1 (1)
  Nausea 38 (35) 1 (1)
  Constipation 15 (14) 0
  Abdominal Pain/Upper Abdominal Pain 25 (23) 0
  Vomiting 13 (12) 0
General Disorders and Administration Site Conditions
  Fatigue 31 (29) 5 (5)
  Pyrexia 27 (25) 1 (1)
  Asthenia 25 (23) 1 (1)
  Edema Peripheral 17 (16) 0
  Infusion and injection site related reactionsb 38 (35) 0
Infections and Infestationsc 52 (48) 12 (11)
Metabolism and Nutrition Disorders
  Anorexia 11 (10) 1 (1)
Musculoskeletal and Connective Tissue Disorders
  Arthralgia 20 (19) 1 (1)
  Pain in Extremity 14 (13) 1 (1)
  Back Pain 13 (12) 2 (2)
  Myalgia 12 (11) 1 (1)
Nervous System Disorders
  Headache 22 (20) 1 (1)
Psychiatric Disorders
  Insomnia 13 (12) 1 (1)
Respiratory, Thoracic and Mediastinal Disorders
  Cough 17 (16) 1 (1)
  Epistaxis 18 (17) 1 (1)
Skin and Subcutaneous Tissue Disorders
  Alopecia 16 (15) 0
  Rash 12 (11) 0
a Occurred in the period between the first dose and 30 days after the last dose.
bIncludes infusion related reaction, injection site erythema, injection site hematoma, injection site hemorrhage, injection site hypersensitivity, injection site induration, injection site inflammation, injection site irritation, injection site mass, injection site edema, injection site pruritus, injection site rash, and injection site reaction.
c Infection includes bacterial, viral, fungal, and non-specified.

Serious adverse reactions were reported for 51% of patients. Serious adverse reactions reported for at least 5% of patients were bone marrow failure and thrombocytopenia (each 10%), and febrile neutropenia (6%). Serious adverse reactions of infections were reported for 8% of patients. Deaths occurred while on study in five (5%) patients with CP CML. Two patients died due to cerebral hemorrhage, one due to multi-organ failure, one due to progression of disease, and one from unknown causes.

Accelerated Phase CML

Median total cycles of exposure was 2 (range 1 to 29), and the median total dose delivered during the trials was 70 mg/m². The median duration of exposure for the 55 patients with accelerated phase CML was 1.9 months (range 0 to 30 months). Of the patients with accelerated phase CML, 86% received 14 days of treatment during cycle 1. By cycles 2 and 3, the percentage of patients receiving 14 days of treatment decreased to 55% and 44% respectively. Of the 40 patients who received at least 2 cycles of treatment, 27 (68%) had at least 1 cycle delay during the trials. The median number of days of cycle delays was greatest for cycle 3 (31 days) and cycle 8 (36 days). Adverse reactions regardless of investigator attribution were reported for 100% patients with accelerated phase CML. A total of 33% of patients had adverse reactions leading to withdrawal. The most frequently occurring adverse reactions leading to withdrawal were leukocytosis (6%), and thrombocytopenia (4%). A total of 84% of patients reported at least 1 Grade 3 or Grade 4 treatment emergent adverse reaction (Table 2).

Table 2: Adverse Reactions Occurringa in at Least 10% of Patients (Chronic Myeloid Leukemia – Accelerated Phase)

Adverse reactions Number (%) of Patients
(N=55)
All reactions Grade 3 or 4 reactions
Patients with at least 1 commonly occurring adverse reaction 55 (100) 47 (86)
Blood and Lymphatic System Disorders
  Anemia 28 (51) 21 (38)
  Febrile Neutropenia 11 (20) 9 (16)
  Neutropenia 11 (20) 10 (18)
  Thrombocytopenia 32 (58) 27 (49)
Gastrointestinal Disorders
  Diarrhea 19 (35) 4 (7)
  Nausea 16 (29) 2 (4)
  Vomiting 9 (16) 1 (2)
  Abdominal Pain/Upper Abdominal Pain 9 (16) 0
General Disorders and Administration Site Conditions
  Fatigue 17 (31) 5 (9)
  Pyrexia 16 (29) 1 (2)
  Asthenia 13 (24) 1 (2)
  Chills 7 (13) 0
  Infusion and injection site related reactionsb 12 (22) 0
Infections and Infestationsc 31 (56) 11 (20)
Metabolism and Nutrition Disorders
  Anorexia 7 (13) 1 (2)
Musculoskeletal and Connective Tissue Disorders
  Pain in Extremity 6 (11) 1 (2)
Nervous System Disorders
  Headache 7 (13) 0
Respiratory, Thoracic and Mediastinal Disorders
  Cough 8 (15) 0
  Dyspnea 6 (11) 1 (2)
  Epistaxis 6 (11) 1 (2)
aOccurred in the period between the first dose and 30 days after the last dose.
bIncludes infusion related reaction, injection site erythema, injection site hematoma, injection site hemorrhage, injection site hypersensitivity, injection site induration, injection site inflammation, injection site irritation, injection site mass, injection site edema, injection site pruritus, injection site rash, and injection site reaction.
cInfection includes bacterial, viral, fungal, and non-specified.

Serious adverse reactions were reported for 60% of patients. Serious adverse reactions reported for at least 5% of patients were febrile neutropenia (18%), thrombocytopenia (9%), anemia (7%), and diarrhea (6%). Serious adverse reactions of infections were reported for 11% of patients.

Death occurred while on study in 5 (9%) patients with AP CML. Two patients died due to cerebral hemorrhage and three due to progression of disease.

Laboratory Abnormalities in Chronic and Accelerated Phase CML

Grade 3/4 laboratory abnormalities reported in patients with chronic and accelerated phase CML are described in Table 3. Myelosuppression occurred in all patients treated with SYNRIBO. [see WARNINGS AND PRECAUTIONS] Five patients with chronic phase CML and 4 patients with accelerated phase CML permanently discontinued SYNRIBO due to pancytopenia, thrombocytopenia, febrile neutropenia, or bone marrow necrosis. An event of hyperosmolar non-ketotic hyperglycemia was reported in one patient in the safety population and a similar case has been reported in the literature. Two patients with chronic phase CML permanently discontinued SYNRIBO due to elevated transaminases.

Table 3: Grade 3/4 Laboratory Abnormalities in Clinical Studies in Patients with Chronic Phase and Accelerated Phase CML

  Chronic Phase % Accelerated Phase %
Hematology Parameters
  Hemoglobin Decreased 62 80
  Leukocytes Decreased 72 61
  Neutrophils Decreased 81 71
  Platelets Decreased 85 88
Biochemistry Parameters
  Alanine aminotransferase (ALT) Increased 6 2
  Bilirubin Increased 9 6
  Creatinine Increased 9 16
  Glucose Increased 10 15
  Uric Acid Increased 56 57
  Glucose Decreased 8 6

Additional Data From Safety Population

The following adverse reactions were reported in patients in the SYNRIBO clinical studies of patients with chronic phase and accelerated phase CML at a frequency of 1% to less than 10%. Within each category, adverse reactions are ranked on the basis of frequency.

Cardiac Disorders: tachycardia, palpitations, acute coronary syndrome, angina pectoris, arrhythmia, bradycardia, ventricular extrasystoles.

Ear and Labyrinth Disorders: ear pain, ear hemorrhage, tinnitus. Eye Disorders: cataract, vision blurred, conjunctival hemorrhage, dry eye, lacrimation increased, conjunctivitis, diplopia, eye pain, eyelid edema.

Gastrointestinal Disorders: stomatitis, mouth ulceration, abdominal distension, dyspepsia, gastroesophageal reflux disease, gingival bleeding, aphthous stomatitis, dry mouth, hemorrhoids, gastritis, gastrointestinal hemorrhage, melena, mouth hemorrhage, oral pain, anal fissure, dysphagia, gingival pain, gingivitis.

General Disorders and Administration Site Conditions: mucosal inflammation, pain, chest pain, hyperthermia, influenza-like illness, catheter site pain, general edema, malaise.

Immune System Disorders: hypersensitivity.

Injury, Poisoning and Procedural Complications: contusion, transfusion reaction.

Metabolism and Nutrition Disorders: decreased appetite, diabetes mellitus, gout, dehydration.

Musculoskeletal and Connective Tissue Disorders: bone pain, myalgia, muscular weakness, muscle spasms, musculoskeletal chest pain, musculoskeletal pain, musculoskeletal stiffness, musculoskeletal discomfort.

Nervous System Disorders: dizziness, cerebral hemorrhage, paresthesia, convulsion, hypoesthesia, lethargy, sciatica, burning sensation, dysgeusia, tremor.

Psychiatric Disorders: anxiety, depression, agitation, confusional state, mental status change.

Renal and Urinary Disorders: dysuria.

Respiratory, Thoracic and Mediastinal Disorders: pharyngolaryngeal pain, nasal congestion, dysphonia, productive cough, rales, rhinorrhea, hemoptysis, sinus congestion.

Skin and Subcutaneous Tissue Disorders: erythema, pruritus, dry skin, petechiae, hyperhidrosis, night sweats, ecchymosis, purpura, skin lesion, skin ulcer, rash erythematous, rash papular, skin exfoliation, skin hyperpigmentation.

Vascular Disorders: hematoma, hypertension, hot flush, hypotension.

DRUG INTERACTIONS

Based on the findings from in vitro drug interaction studies with SYNRIBO, no clinical drug interaction trials were warranted. [see CLINICAL PHARMACOLOGY]

Warnings & Precautions

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Myelosuppression

In uncontrolled trials with SYNRIBO, patients with chronic phase and accelerated phase CML experienced NCI CTC (version 3.0) Grade 3 or 4 thrombocytopenia (85%, 88%), neutropenia (81%, 71%), and anemia (62%, 80%), respectively. Fatalities related to myelosuppression occurred in 3% of patients in the safety population (N=163). Patients with neutropenia are at increased risk for infections, and should be monitored frequently and advised to contact a physician if they have symptoms of infection or fever. Monitor complete blood counts weekly during induction and initial maintenance cycles and every two weeks during later maintenance cycles, as clinically indicated. In clinical trials myelosuppression was generally reversible and usually managed by delaying next cycle and/or reducing days of treatment with SYNRIBO. [see DOSAGE AND ADMINISTRATION and ADVERSE REACTIONS]

Bleeding

SYNRIBO causes severe thrombocytopenia which increases the risk of hemorrhage. In clinical trials with CP and AP CML patients, a high incidence of Grade 3 and 4 thrombocytopenia (85% and 88%, respectively) was observed. Fatalities from cerebral hemorrhage occurred in 2% of patients treated with SYNRIBO in the safety population. Severe, non-fatal, gastrointestinal hemorrhages occurred in 2% of patients in the same population. Most bleeding events were associated with severe thrombocytopenia. Monitor platelet counts as part of the CBC monitoring as recommended. [see Myelosuppression] Avoid anticoagulants, aspirin, and non-steroidal anti-inflammatory drugs (NSAIDs) when the platelet count is less than 50,000/μL as they may increase the risk of bleeding.

Hyperglycemia

SYNRIBO can induce glucose intolerance. Grade 3 or 4 hyperglycemia was reported in 11% of patients in the safety population. Hyperosmolar non-ketotic hyperglycemia occurred in 1 patient treated with SYNRIBO in the safety population. Monitor blood glucose levels frequently, especially in patients with diabetes or risk factors for diabetes. Avoid SYNRIBO in patients with poorly controlled diabetes mellitus until good glycemic control has been established.

Embryo-Fetal Toxicity

SYNRIBO can cause fetal harm when administered to a pregnant woman. Omacetaxine mepesuccinate caused embryo-fetal death in animals. Females of reproductive potential should avoid becoming pregnant while being treated with SYNRIBO. There are no adequate and well-controlled studies of SYNRIBO in pregnant women. If this drug is used during pregnancy, or if the patient becomes pregnant while receiving this drug, the patient should be apprised of the potential hazard to the fetus. [see Use in Specific Populations]

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

No carcinogenicity studies have been conducted with omacetaxine mepesuccinate. Omacetaxine mepesuccinate was genotoxic in an in vitro chromosomal aberration test system in Chinese hamster ovary (CHO) cells, but was not mutagenic when tested in an in vitro bacterial cell assay (Ames test), and it did not induce genetic damage using an in vivo mouse micronucleus assay. SYNRIBO may impair male fertility. Studies in mice demonstrated adverse effects on male reproductive organs. Bilateral degeneration of the seminiferous tubular epithelium in testes and hypospermia/aspermia in the epididymides were reported in the highest dose group (2.33 mg/kg/day reduced to 1.67 mg/kg/day; 7 to 5 mg/m²/day) following subcutaneous injection of omacetaxine mepesuccinate for six cycles over six months. The doses used in the mice were approximately two to three times the clinical dose (2.5 mg/m²/day) based on body surface area.

Use In Specific Populations

Pregnancy

Pregnancy Category D

[see WARNINGS AND PRECAUTIONS]

Based on its mechanism of action and findings from animal studies, SYNRIBO can cause fetal harm when administered to pregnant women. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to a fetus. In an embryo-fetal development study, pregnant mice were administered omacetaxine mepesuccinate subcutaneously during the period of organogenesis at doses of 0.21 or 0.41 mg/kg/day. Drug-related adverse effects included embryonic death, an increase in unossified bones/reduced bone ossification and decreased fetal body weights. Fetal toxicity occurred at doses of 0.41 mg/kg (1.23 mg/m²) which is approximately half the recommended daily human dose on a body surface area basis.

Nursing Mothers

It is not known whether omacetaxine mepesuccinate is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reaction in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

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

Geriatric Use

In the chronic and accelerated phase CML efficacy populations 23 (30%) and 16 (46%) patients were ≥ 65 years of age. For the age subgroups of < 65 years of age and ≥ 65 years of age, there were differences between the subgroups, with higher rates of major cytogenetic responses (MCyRs) in younger patients with CP CML compared with older patients (23% vs. 9%, respectively) and higher rates of major hematologic responses (MaHRs) in older patients with AP CML compared with younger patients (31% vs. 0%, respectively). Patients ≥ 65 years of age were more likely to experience toxicity, most notably hematologic toxicity.

Renal Impairment

No formal studies assessing the impact of renal impairment on the pharmacokinetics of omacetaxine mepesuccinate have been conducted.

Hepatic Impairment

No formal studies assessing the impact of hepatic impairment on the pharmacokinetics of omacetaxine mepesuccinate have been conducted.

Effect of Gender

Of the 76 patients included in the chronic phase CML population efficacy analysis, 47 (62%) of the patients were men and 29 (38%) were women. For patients with chronic phase CML, the MCyR rate in men was higher than in women (21% vs. 14%, respectively). There were differences noted in the safety profile of omacetaxine mepesuccinate in men and women with chronic phase CML although the small number of patients in each group prevents a definitive assessment. There were inadequate patient numbers in the accelerated phase subset to draw conclusions regarding a gender effect on efficacy.

Overdosage & Contraindications

OVERDOSE

A patient in the clinical program received an overdose of 2.5 mg/m²twice daily for 5 days. The patient presented with gastrointestinal disorders, gingival hemorrhage, alopecia, and Grade 4 thrombocytopenia and neutropenia. When SYNRIBO treatment was temporarily interrupted the gastrointestinal disorders and hemorrhagic syndrome resolved, and neutrophil values returned to within normal range. The alopecia and thrombocytopenia (Grade 1) improved, and SYNRIBO was restarted.

CONTRAINDICATIONS

None.

Clinical Pharmacology

CLINICAL PHARMACOLOGY

Mechanism Of Action

The mechanism of action of omacetaxine mepesuccinate has not been fully elucidated but includes inhibition of protein synthesis and is independent of direct Bcr-Abl binding. Omacetaxine mepesuccinate binds to the A-site cleft in the peptidyl-transferase center of the large ribosomal subunit from a strain of archaeabacteria. In vitro, omacetaxine mepesuccinate reduced protein levels of the Bcr-Abl oncoprotein and Mcl-1, an anti-apoptotic Bcl-2 family member. Omacetaxine mepesuccinate showed activity in mouse models of wild-type and T315I mutated Bcr-Abl CML.

Pharmacokinetics

The dose proportionality of omacetaxine mepesuccinate is unknown. A 90% increase in systemic exposure to omacetaxine mepesuccinate was observed between the first dose and steady state.

Absorption

The absolute bioavailability of omacetaxine mepesuccinate has not been determined. Omacetaxine mepesuccinate is absorbed following subcutaneous administration, and maximum concentrations are achieved after approximately 30 minutes.

Distribution

The steady-state (mean ± SD) volume of distribution of omacetaxine mepesuccinate is approximately 141 ± 93.4 L following subcutaneous administration of 1.25 mg/m²twice daily for 11 days. The plasma protein binding of omacetaxine mepesuccinate is less than or equal to 50%.

Metabolism

Omacetaxine mepesuccinate is primarily hydrolyzed to 4'-DMHHT via plasma esterases with little hepatic microsomal oxidative and/or esterase-mediated metabolism in vitro.

Elimination

The major elimination route of omacetaxine mepesuccinate is unknown. The mean percentage of omacetaxine mepesuccinate excreted unchanged in the urine is less than 15%. The mean half-life of omacetaxine mepesuccinate following subcutaneous administration is approximately 6 hours.

Drug Interactions

Cytochrome P450 Enzymes (CYPs): Omacetaxine mepesuccinate is not a substrate of CYP450 enzymes in vitro. Omacetaxine mepesuccinate and 4'-DMHHT do not inhibit major CYPs in vitro at concentrations that can be expected clinically. The potential for omacetaxine mepesuccinate or 4'-DMHHT to induce CYP450 enzymes has not been determined.

Transporter Systems: Omacetaxine mepesuccinate is a P-glycoprotein (P-gp) substrate in vitro. Omacetaxine mepesuccinate and 4'DMHHT do not inhibit P-gp mediated efflux of loperamide in vitro at concentrations that can be expected clinically.

Assessment For Risk Of QT Prolongation

In an uncontrolled pharmacokinetic study there were no reports of QTcF > 480 ms or ΔQTcF > 60 ms in 21 treated patients who received omacetaxine mepesuccinate 1.25 mg/m²BID for 14 consecutive days. There was no evidence for concentration-dependent increases in QTc for omacetaxine mepesuccinate or 4'-DMHHT. Although the mean effect on QTc was 4.2 ms (upper 95% CI: 9.5 ms), QTc effects less than 10 ms cannot be verified due to the absence of a placebo and positive controls.

Clinical Studies

The efficacy of SYNRIBO was evaluated using a combined cohort of adult patients with CML from two trials. The combined cohort consisted of patients who had received 2 or more approved TKIs and had, at a minimum, documented evidence of resistance or intolerance to dasatinib and/or nilotinib. Resistance was defined as one of the following: no complete hematologic response (CHR) by 12 weeks (whether lost or never achieved); or no cytogenetic response by 24 weeks (i.e., 100% Ph positive [Ph+]) (whether lost or never achieved); or no major cytogenetic response (MCyR) by 52 weeks (i.e., ≥ 35% Ph+) (whether lost or never achieved); or progressive leukocytosis. Intolerance was defined as one of the following: 1) Grade 3-4 non-hematologic toxicity that does not resolve with adequate intervention; or 2) Grade 4 hematologic toxicity lasting more than 7 days; or 3) any Grade ≥ 2 toxicity that is unacceptable to the patient.

Patients with NYHA class III or IV heart disease, active ischemia or other uncontrolled cardiac conditions were excluded. Patients were treated with omacetaxine mepesuccinate at a dose of 1.25 mg/m²administered subcutaneously twice daily for 14 consecutive days every 28 days (induction cycle). Responding patients were then treated with the same dose and twice daily schedule for 7 consecutive days every 28 days (maintenance cycle). Patients were allowed to continue to receive maintenance treatment for up to 24 months. Responses were adjudicated by an independent Data Monitoring Committee (DMC).

Chronic Phase CML (CP CML)

A total of 76 patients with chronic phase CML were included in the efficacy analysis. The demographics were: median age 59 years, 62% were male, 30% were 65 years of age or older, 80% were Caucasian, 5% were African-American, 4% were Asian and 4% were Hispanic. Thirty-six (47%) patients had failed treatment with imatinib, dasatinib, and nilotinib. Most patients had also received prior non-TKI treatments, most commonly hydroxyurea (54%), interferon (30%), and/or cytarabine (29%). The efficacy endpoint was based on MCyR (adjudicated by a DMC).

Table 4: Efficacy Results Evaluated by DMC for Patients with CP CML

  Patients
(N=76)
Primary Response – MCyR
  Total with MCyR, n (%) 14 (18.4)
  95% confidence interval (10.5% – 29.0%)
Cytogenetic Response, n (%)
  Confirmed complete 6 (7.9)
  Confirmed partial 3 (3.9)
Cytogenetic response evaluation is based on standard cytogenetic analysis (at least 20 metaphases).
Complete: 0% Ph+ cells, Partial > 0% to 35% Ph+ cells

The mean time to MCyR onset in the 14 patients was 3.5 months. The median duration of MCyR for the 14 patients was 12.5 months (Kaplan-Meier estimate).

Accelerated Phase CML (AP CML)

A total of 35 patients with accelerated phase CML were included in the efficacy analysis. The demographics were: median age was 63 years, 57% were male, 46% were 65 years of age or older, 68% were Caucasian, 23% were African-American, 3% were Asian and 3% were Hispanic. Twenty-two (63%) of 35 patients with accelerated phase had failed treatment with imatinib, dasatinib, and nilotinib. Most patients had also received prior non-TKI treatments, most commonly hydroxyurea (43%), interferon (31%), and/or cytarabine (29%). The efficacy endpoint was assessed based on MCyR and MaHR (complete hematologic response [CHR] or no evidence of leukemia [NEL]). The efficacy results for the patients with accelerated phase as adjudicated by the DMC are shown in Table 5.

Table 5: Efficacy Results Evaluated by DMC for Patients with AP CML

  Patients
(N=35)
Primary Response – MaHR
  Total with MaHR, n (%) 5 (14.3)
  95% confidence interval (4.5% -30.3%)
  CHR 4 (11.4)
  NEL 1 (2.9)
Primary Response – MCyR
Total with MCyR, n (%) 0
MaHR is defined as complete hematologic response (CHR) or no evidence of leukemia (NEL): CHR -absolute neutrophil count ≥ 1.5 × 109/liter, platelets ≥ 100 × 109/liter, no blood blasts, bone marrow blasts < 5%, no extramedullary disease; NEL -Morphologic leukemia-free state, defined as < 5% bone marrow blasts.

The mean time to response onset in the 5 patients was 2.3 months. The median duration of MaHR for the 5 patients was 4.7 months (Kaplan-Meier estimate).

Medication Guide

PATIENT INFORMATION

Instructions for Use

SYNRIBO®
(sin-RYE-bo)
(omacetaxine mepesuccinate) for Injection, for Subcutaneous Use

Read this Instructions for Use before you inject SYNRIBO for the first time and each time you get a refill. Also read the Medication Guide for SYNRIBO. 

Before you or your caregiver injects SYNRIBO, your healthcare provider will show you how to properly: 

  • handle syringes and inject SYNRIBO
  • dispose of used supplies for injecting SYNRIBO
  • clean up any spilled SYNRIBO

Important:

  • Be sure that you store SYNRIBO exactly as your healthcare provider tells you to. See the section “How should I store SYNRIBO?” in the Medication Guide.  
  • Never try to re-cap the needle. This could cause a needle-stick injury.
  • If SYNRIBO comes into contact with your skin, wash the area well with soap and water.

Your healthcare provider will arrange for you to receive all of the supplies that you will need for each injection of SYNRIBO:

  • syringe with attached needle, containing SYNRIBO for injection
  • protective eyewear, such as protective eyeglasses (not regular eyeglasses) or face shield
  • gloves
  • disposal biohazard container
  • absorbent pads for use to clean up an accidental spill of SYNRIBO
  • alcohol swabs
  • gauze pads

You may also need an adhesive bandage.

Never mix SYNRIBO yourself. If you don't receive syringes already filled with SYNRIBO, contact your doctor or pharmacy.  

Step 1. Preparing to give an injection of SYNRIBO.

  • Find a clean flat work surface.    
  • Wash your hands well with soap and water. 
  • Put on a pair of gloves and your protective eyewear before you handle the syringe containing SYNRIBO. Wearing gloves and protective eyewear protects you from splashes or spills. See Figure A.
  • Look at the date printed on the syringe label to make sure that the expiration date has not passed. Do not use if the expiration date has passed and contact your doctor or pharmacy immediately.
  • Gather the rest of your supplies and place them on your work surface.

Figure A

Put

Step 2. Choose an injection site.

  • You may inject SYNRIBO into your thigh or stomach-area (abdomen). See Figure B. The injection can be given in the back of your arm if a caregiver is giving the injection. See Figure C.   
  • Use a different site for each injection to help decrease tenderness at the injection site. Each injection site should be at least 1 inch away from any recently used injection site.
  • Do not inject SYNRIBO into areas of your skin that are tender, red, bruised, hard, or that have scars or stretch marks.   

Choose

Step 3. Prepare the injection site.

  • Clean the injection site well with an alcohol wipe and allow it to air dry. See Figure D.

Clean

Step 4. Inject SYNRIBO.

  • Carefully remove the needle cap by pulling, taking care not to stick yourself. See Figure E.   
  • Do not press down on the plunger.
Carefully

  • With one hand, pinch skin of injection site between your thumb and forefinger. See Figure F.

Pinch

  • With your other hand, hold the syringe at a 45 degree or 90 degree angle to your skin. Use a quick dart-like motion to insert the needle through the skin at the injection site. See Figures G and H. The needle should go through the skin but not into your muscle.

Injecting

  • Slowly push down on the plunger with your thumb until syringe is empty. See Figure I. 

Slowly

  • Stop pinching your skin. Quickly remove needle and then apply pressure on injection site with a dry gauze pad. You can put a small adhesive bandage over the injection site if there is bleeding. See Figure J.

Apply

  • Follow the instructions below for how to dispose of the syringe, needle, and other supplies used to give your injection. Never try to re-cap the needle. This could cause a needle-stick injury.
  • Remove your gloves. Wash your hands right away with soap and water, and then remove your protective eyewear.

How should I throw away (dispose of) used SYNRIBO syringes, needles, and other supplies?

  • Throw away (dispose of) used SYNRIBO syringes, needles, and other used supplies in an appropriate biohazard container.
  • Return the biohazard container to your healthcare provider for disposal.  
  • Do not place used syringes, needles, or other supplies in a household trash or recycle container. Do not re-cap or clip the used needle. This could cause a needle-stick injury.
  • Do not throw away the protective eyewear. You will need them for each dose of SYNRIBO.

What should I do in case of an accidental SYNRIBO spill?

  • Your healthcare provider will arrange for you to receive supplies to use in case you spill SYNRIBO.  
  • Follow your healthcare provider's instructions about how to clean up a SYNRIBO spill.
  • Do not touch a spill unless you are wearing gloves and protective eyewear.  
  • Use an absorbent pad to wipe up the spill. Wash the area with soap and water. Use an extra absorbent pad or paper towel to dry the area.
  • Place the pad, gloves, and other supplies that were used to clean the spill in the biohazard container.   
  • Call your healthcare provider right away to report the spill.   

This Instructions for Use has been approved by the U.S. Food and Drug Administration

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