Arsenic Trioxide

Arsenic trioxide injection is an arsenical indicated: For induction of remission and consolidation in patients with APL who are refractory to, or have relapsed from, retinoid and anthracycline chemotherapy, and whose APL is characterized by the presence of the t(15;17) translocation or PML/RAR-alpha gene expression. ( 1.2 )

1.2 Relapsed or Refractory APL Arsenic trioxide injection is indicated for induction of remission and consolidation in patients with APL who are refractory to, or have relapsed from, retinoid and anthracycline chemotherapy, and whose APL is characterized by the presence of the t(15;17) translocation or PML/RAR-alpha gene expression.

Injection: 10 mg/10 mL (1 mg/mL) arsenic trioxide clear solution in a single-dose vial. Injection: 12 mg/6 mL (2 mg/mL) arsenic trioxide clear solution in a single-dose vial. Injection: 10 mg/10 mL (1 mg/mL) and 12 mg/6 mL (2 mg/mL) arsenic trioxide in single-dose vials. ( 3 )

Arsenic trioxide is contraindicated in patients with hypersensitivity to arsenic. Hypersensitivity to arsenic. ( 4 )

Hepatotoxicity : Monitor hepatic function tests at least twice weekly during induction and at least once weekly during consolidation. Withhold arsenic trioxide for certain elevations in AST, alkaline phosphatase and bilirubin and resume at reduced dose upon resolution. ( 2.3 , 5.4 ) Ca r c in og e n e sis: Arsenic trioxide is a human carcinogen. Monitor patients for the development of second primary malignancies. ( 5.5 ) Embryo – F e ta l Toxicity: Can cause fetal harm. Advise of potential risk to a fetus and use of effective contraception. ( 5.6 , 8.1 , 8.3 )

5.1 Differentiation Syndrome Differentiation syndrome, which may be life-threatening or fatal, has been observed in patients with acute promyelocytic leukemia (APL) treated with arsenic trioxide. In clinical trials, 16 to 23% of patients treated with arsenic trioxide for APL developed differentiation syndrome. Signs and symptoms include unexplained fever, dyspnea, hypoxia, acute respiratory distress, pulmonary infiltrates, pleural or pericardial effusion, weight gain, peripheral edema, hypotension, renal insufficiency, hepatopathy and multi-organ dysfunction. Differentiation syndrome has been observed with and without concomitant leukocytosis, and it has occurred as early as day 1 of induction to as late as the second month induction therapy. If differentiation syndrome is suspected, temporarily withhold arsenic trioxide injection and immediately initiate dexamethasone 10 mg intravenously every 12 hours and hemodynamic monitoring until resolution of signs and symptoms for a minimum of 3 days [see Dosage and Administration (2.3) ] .

5.2 Cardiac Conduction Abnormalities Patients treated with arsenic trioxide can develop QTc prolongation, torsade de pointes, and complete atrioventricular block. In the clinical trial of patients with relapsed or refractory APL treated with arsenic trioxide monotherapy, 40% had at least one ECG tracing with a QTc interval greater than 500 msec. A prolonged QTc was observed between 1 and 5 weeks after start of arsenic trioxide infusion, and it usually resolved by 8 weeks after arsenic trioxide infusion. There are no data on the effect of arsenic trioxide on the QTc interval during the infusion of the drug. The risk of torsade de pointes is related to the extent of QTc prolongation, concomitant administration of QTc prolonging drugs, a history of torsade de pointes, pre-existing QTc interval prolongation, congestive heart failure, administration of potassium-wasting diuretics, or other conditions that result in hypokalemia or hypomagnesemia. The risk may be increased when arsenic trioxide is coadministered with medications that can lead to electrolyte abnormalities (such as diuretics or amphotericin B) [see Drug Interactions (7) ] . Prior to initiating therapy with arsenic trioxide, assess the QTc interval by electrocardiogram, correct pre-existing electrolyte abnormalities, and consider discontinuing drugs known to prolong QTc interval. Do not administer arsenic trioxide to patients with a ventricular arrhythmia or prolonged QTc. If possible, discontinue drugs that are known to prolong the QTc interval. If it is not possible to discontinue the interacting drug, perform cardiac monitoring frequently [see Drug Interactions (7) ]. During arsenic trioxide therapy, maintain potassium concentrations above 4 mEq/L and magnesium concentrations above 1.8 mg/dL. Monitor ECG weekly and more frequently for clinically unstable patients. For patients who develop a QTc Framingham greater than 450 msec for men or greater than 460 msec for women, withhold arsenic trioxide and any medication known to prolong the QTc interval. Correct electrolyte abnormalities. When the QTc normalizes, and electrolyte abnormalities are corrected, resume arsenic trioxide at a reduced dose [see Dosage and Administration (2.3) ] .

5.3 Encephalopathy Serious encephalopathies were reported in patients receiving arsenic trioxide. Monitor patients for neurological symptoms, such as confusion, decreased level of consciousness, seizures, cognitive deficits, ataxia, visual symptoms and ocular motor dysfunction. Advise patients and caregivers of the need for close observation. W er nicke’s Encephalopathy Wernicke’s encephalopathy occurred in patients receiving arsenic trioxide. Wernicke’s encephalopathy is a neurologic emergency that can be prevented and treated with thiamine. Consider testing thiamine levels in patients at risk for thiamine deficiency (e.g., chronic alcohol use, malabsorption, nutritional deficiency, concomitant use of furosemide). Administer parenteral thiamine in patients with or at risk for thiamine deficiency. Monitor patients for neurological symptoms and nutritional status while receiving arsenic trioxide. If Wernicke’s encephalopathy is suspected, immediately interrupt arsenic trioxide and initiate parenteral thiamine. Monitor until symptoms resolve or improve and thiamine levels normalize.

5.4 Hepatotoxicity Long-term liver abnormalities can occur in patients with APL treated with arsenic trioxide. During treatment with arsenic trioxide injection, monitor hepatic function tests at least twice weekly during induction and at least once weekly during consolidation. Withhold arsenic trioxide injection if elevations in AST or alkaline phosphatase occur to greater than 5 times the upper limit of normal and/or elevation in serum total bilirubin occurs to greater than 3 times the upper limit of normal and resume at reduced dose upon resolution [see Dosage and Administration (2.3) ] .

5.5 Carcinogenesis The active ingredient of arsenic trioxide, is a human carcinogen. Monitor patients for the development of second primary malignancies.

5.6 Embryo-Fetal Toxicity Arsenic trioxide can cause fetal harm when administered to a pregnant woman. Arsenic trioxide was embryolethal and teratogenic in rats when administered on gestation day 9 at a dose approximately 10 times the recommended human daily dose on a mg/m² basis. A related trivalent arsenic, sodium arsenite, produced teratogenicity when administered during gestation in mice at a dose approximately 5 times the projected human dose on a mg/m² basis and in hamsters at an intravenous dose approximately equivalent to the projected human daily dose on a mg/m² basis. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with arsenic trioxide injection and for 6 months after the last dose. Advise males with female partners of reproductive potential to use effective contraception during treatment with arsenic trioxide injection and for 3 months after the last dose [see Use in Specific Populations (8.1 , 8.3 )] .

The following clinically significant adverse reactions are described elsewhere in the labeling: Differentiation Syndrome [see Warnings and Precautions (5.1) ] Cardiac Conduction Abnormalities [see Warnings and Precautions (5.2) ] Encephalopathy [see Warnings and Precautions (5.3) ] Hepatotoxicity [see Warnings and Precautions (5.4) ] Carcinogenesis [see Warnings and Precautions (5.5) ] The most common adverse reactions (>30%) are nausea, cough, fatigue, pyrexia, headache, abdominal pain, vomiting, tachycardia, diarrhea, dyspnea, hypokalemia, leukocytosis, hyperglycemia, hypomagnesemia, insomnia, dermatitis, edema, QTc prolongation, rigors, sore throat, arthralgia, paresthesia, and pruritus ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Avet Pharmaceuticals Inc. at 1-866-901-DRUG (3784) 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. R e lapsed or Refractory APL Safety information was available for 52 patients with relapsed or refractory APL who participated in clinical trials of arsenic trioxide. Forty patients in the Study PLRXAS01 received the recommended dose of 0.15 mg/kg, of whom 28 completed both induction and consolidation cycles. An additional 12 patients with relapsed or refractory APL received doses generally similar to the recommended dose. Serious adverse reactions observed in the 40 patients with refractory or relapsed APL enrolled in Study PLRXAS01 included differentiation syndrome (n=3), hyperleukocytosis (n=3), QTc interval ≥500 msec (n=16, 1 with torsade de pointes), atrial dysrhythmias (n=2), and hyperglycemia (n=2). The most common adverse reactions (>30%) were nausea, cough, fatigue, pyrexia, headache, abdominal pain, vomiting, tachycardia, diarrhea, dyspnea, hypokalemia, leukocytosis, hyperglycemia, hypomagnesemia, insomnia, dermatitis, edema, QTc prolongation, rigors, sore throat, arthralgia, paresthesia, and pruritus. Table 5 describes the adverse reactions in patients aged 5 to 73 years with APL who received arsenic trioxide at the recommended dose. Similar adverse reactions profiles were seen in the other patient populations who received arsenic trioxide. Table 5: Adverse Reactions (≥5%) in Patients with Relapsed or Refractory APL Who Received Arsenic Trioxide Injection in Study PLRXAS01 B ody System Adverse reaction Any Grade Adverse Reactions G r ade ≥3 Adverse Reactions n % n % G astrointestinal disorders Nausea 30 75 Abdominal pain (lower & upper) 23 58 4 10 Vomiting 23 58 Diarrhea 21 53 Sore throat 14 35 Constipation 11 28 1 3 Anorexia 9 23 Appetite decreased 6 15 Loose stools 4 10 Dyspepsia 4 10 Oral blistering 3 8 Fecal incontinence 3 8 Gastrointestinal hemorrhage 3 8 Dry mouth 3 8 Abdominal tenderness 3 8 Diarrhea hemorrhagic 3 8 Abdominal distension 3 8 Respiratory Cough 26 65 Dyspnea 21 53 4 10 Epistaxis 10 25 Hypoxia 9 23 4 10 Pleural effusion 8 20 1 3 Post nasal drip 5 13 Wheezing 5 13 Decreased breath sounds 4 10 Crepitations 4 10 Rales 4 10 Hemoptysis 3 8 Tachypnea 3 8 Rhonchi 3 8 G e ne r al disorders and administration site conditions Fatigue 25 63 2 5 Pyrexia (fever) 25 63 2 5 Edema – non-specific 16 40 Rigors 15 38 Chest pain 10 25 2 5 Injection site pain 8 20 Pain – non-specific 6 15 1 3 Injection site erythema 5 13 Weight gain 5 13 Injection site edema 4 10 Weakness 4 10 2 5 Hemorrhage 3 8 Weight loss 3 8 Drug hypersensitivity 2 5 1 3 Nervous system disorders Headache 24 60 1 3 Insomnia 17 43 1 3 Paresthesia 13 33 2 5 Dizziness (excluding vertigo) 9 23 Tremor 5 13 Convulsion 3 8 2 5 Somnolence 3 8 Coma 2 5 2 5 Cardiac disorders Tachycardia 22 55 ECG QT corrected interval prolonged >500 msec 16 40 Palpitations 4 10 ECG abnormal other than QT interval prolongation 3 8 Met abolism and nutrition disorders Hypokalemia 20 50 5 13 Hypomagnesemia 18 45 5 13 Hyperglycemia 18 45 5 13 ALT increased 8 20 2 5 Hyperkalemia 7 18 2 5 AST increased 5 13 1 3 Hypocalcemia 4 10 Hypoglycemia 3 8 Acidosis 2 5 Hematologic disorders Leukocytosis 20 50 1 3 Anemia 8 20 2 5 Thrombocytopenia 7 18 5 13 Febrile neutropenia 5 13 3 8 Neutropenia 4 10 4 10 Disseminated intravascular coagulation 3 8 3 8 Lymphadenopathy 3 8 Sk in and subcutaneous tissue disorders Dermatitis 17 43 Pruritus 13 33 1 3 Ecchymosis 8 20 Dry skin 6 15 Erythema – non-specific 5 13 Increased sweating 5 13 Facial edema 3 8 Night sweats 3 8 Petechiae 3 8 Hyperpigmentation 3 8 Non-specific skin lesions 3 8 Urticaria 3 8 Local exfoliation 2 5 Eyelid edema 2 5 M u sculoskeletal, connective tissue, and bone disorders Arthralgia 13 33 3 8 Myalgia 10 25 2 5 Bone pain 9 23 4 10 Back pain 7 18 1 3 Neck pain 5 13 Pain in limb 5 13 2 5 P sychiatric disorders Anxiety 12 30 Depression 8 20 Agitation 2 5 Confusion 2 5 Vascular disorders Hypotension 10 25 2 5 Flushing 4 10 Hypertension 4 10 Pallor 4 10 Infections and infestations Sinusitis 8 20 Herpes simplex 5 13 Upper respiratory tract infection 5 13 1 3 Bacterial infection – non-specific 3 8 1 3 Herpes zoster 3 8 Nasopharyngitis 2 5 Oral candidiasis 2 5 Sepsis 2 5 2 5 Reproductive system disorders Vaginal hemorrhage 5 13 Intermenstrual bleeding 3 8 Ocular disorders Eye irritation 4 10 Blurred vision 4 10 Dry eye 3 8 Painful red eye 2 5 Renal and urinary disorders Renal failure 3 8 1 3 Renal impairment 3 8 Oliguria 2 5 Incontinence 2 5 E ar disorders Earache 3 8 Tinnitus 2 5 Other Clinically Relevant Adverse Reactions L e uk ocytosis Arsenic trioxide can induce proliferation of leukemic promyelocytes resulting in a rapid increase in white blood cell count. Leukocytosis greater than 10 Gi/L developed during induction therapy in 50% of patients receiving arsenic trioxide monotherapy for relapsed/refractory APL. In the relapsed/refractory setting, a relationship did not exist between baseline WBC counts and development of hyperleukocytosis nor baseline WBC counts and peak WBC counts.

6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval use of arsenic trioxide injection. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate the frequency or establish a causal relationship to drug exposure. Cardiac disorders: Ventricular extrasystoles in association with QT prolongation, ventricular tachycardia in association with QT prolongation, including torsade de pointes, atrioventricular block, and congestive heart failure. Ear and labyrinth disorders: Deafness Hematologic disorders: Pancytopenia, bone marrow necrosis Infections: Herpes zoster Investigations: Gamma-glutamyltransferase increased Musculoskeletal and connective tissue disorders: Bone pain, myalgia, rhabdomyolysis Neoplasms benign, malignant and unspecified: Melanoma, pancreatic cancer, squamous cell carcinoma Nervous system disorders: Peripheral neuropathy, paresis, seizures, confusion, encephalopathy, Wernicke’s encephalopathy, posterior reversible encephalopathy syndrome Skin and subcutaneous tissue disorders: Toxic epidermal necrolysis

Drugs That Can Prolong the QT/QTc Interval Concomitant use of these drugs and arsenic trioxide may increase the risk of serious QT/QTc interval prolongation [see Warnings and Precautions (5.1) ] . Discontinue or replace with an alternative drug that does not prolong the QT/QTc interval while the patient is using arsenic trioxide. Monitor ECGs more frequently in patients when it is not feasible to avoid concomitant use. Drugs That Can Lead to Electrolyte Abnormalities Electrolyte abnormalities increase the risk of serious QT/QTc interval prolongation [see Warnings and Precautions (5.1) ] . Avoid concomitant use of drugs that can lead to electrolyte abnormalities. Monitor electrolytes more frequently in patients who must receive concomitant use of these drugs and arsenic trioxide. Drugs That Can Lead to Hepatotoxicity Use of these drugs and arsenic trioxide may increase the risk of serious hepatotoxicity [see Warnings and Precautions (5.4) ] . Discontinue or replace with an alternative drug that does not cause hepatotoxicity while the patient is using arsenic trioxide. Monitor liver function tests more frequently in patients when it is not feasible to avoid concomitant use.

Lactation : Advise not to breastfeed. ( 8.2 ) Renal Impairment : Monitor patients with severe renal impairment (creatinine clearance less than 30 mL/min) for toxicity when treated with arsenic trioxide; dose reduction may be warranted. ( 8.6 ) Hepatic Impairment : Monitor patients with severe hepatic impairment (Child-Pugh Class C) for toxicity when treated with arsenic trioxide. ( 8.7 )

8.1 Pregnancy Risk Summary Based on the mechanism of action [see Clinical Pharmacology (12.1) ] and findings in animal studies, arsenic trioxide can cause fetal harm when administered to a pregnant woman. Arsenic trioxide was embryolethal and teratogenic in rats when administered on gestation day 9 at a dose approximately 10 times the recommended human daily dose on a mg/m² basis ( see Data ). A related trivalent arsenic, sodium arsenite, produced teratogenicity when administered during gestation in mice at a dose approximately 5 times the projected human dose on a mg/m² basis and in hamsters at an intravenous dose approximately equivalent to the projected human daily dose on a mg/m² basis. There are no studies with the use of arsenic trioxide in pregnant women, and limited published data on arsenic trioxide use during pregnancy are insufficient to inform a drug- associated risk of major birth defects and miscarriage. Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. 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% to 4% and 15% to 20%, respectively. Data Human Data One patient was reported to deliver a live infant with no reported congenital anomalies after receiving arsenic trioxide during the first five months of pregnancy. A second patient became pregnant three months after discontinuing arsenic trioxide and was reported to have a normal pregnancy outcome. A third patient was a pregnant healthcare provider who experienced dermal contact with liquid arsenic trioxide and had a normal pregnancy outcome after treatment and monitoring. A fourth patient who became pregnant while receiving arsenic trioxide had a miscarriage. Animal Data Studies in pregnant mice, rats, hamsters, and primates have shown that inorganic arsenicals cross the placental barrier when given orally or by injection. An increase in resorptions, neural-tube defects, anophthalmia and microphthalmia were observed in rats administered 10 mg/kg of arsenic trioxide on gestation day 9 (approximately 10 times the recommended human daily dose on a mg/m² basis). Similar findings occurred in mice administered a 10 mg/kg dose of a related trivalent arsenic, sodium arsenite (approximately 5 times the projected human dose on a mg/m² basis), on gestation days 6, 7, 8, or 9. Intravenous injection of 2 mg/kg sodium arsenite (approximately equivalent to the projected human daily dose on a mg/m² basis) on gestation day 7 (the lowest dose tested) resulted in neural-tube defects in hamsters.

8.2 Lactation Risk Summary Arsenic trioxide is excreted in human milk. There are no data on the effects of arsenic trioxide on the breastfed child or on milk production. Because of the potential for serious adverse reactions in a breastfed child, advise women not to breastfeed during treatment with arsenic trioxide and for 2 weeks after the final dose.

8.3 Females and Males of Reproductive Potential Arsenic trioxide can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1) ]. Pregnancy Testing Conduct pregnancy testing in females of reproductive potential prior to initiation of arsenic trioxide. Contraception Females Advise females of reproductive potential to use effective contraception during treatment with arsenic trioxide and for 6 months after the final dose. Males Advise males with female partners of reproductive potential to use effective contraception during treatment with arsenic trioxide and for 3 months after the final dose. Infertility Males Based on testicular toxicities including decreased testicular weight and impaired spermatogenesis observed in animal studies, arsenic trioxide may impair fertility in males of reproductive potential [see Nonclinical Toxicology (13.1) ] .

8.4 Pediatric Use The safety and efficacy of arsenic trioxide as a single agent for treatment of pediatric patients with relapsed or refractory APL is supported by the pivotal phase 2 study in 40 patients with relapsed or refractory APL. Five patients below the age of 18 years (age range: 5 to 16 years) were treated with arsenic trioxide at the recommended dose of 0.15 mg/kg/day. A literature review included an additional 17 patients treated with arsenic trioxide for relapsed or refractory APL, with ages ranging from 4 to 21 years. No differences in efficacy and safety were observed by age.

8.5 Geriatric Use Use of arsenic trioxide as monotherapy in patients with relapsed or refractory APL is supported by the open-label, single-arm trial that included 6 patients aged 65 and older (range: 65 to 73 years). A literature review included an additional 4 patients aged 69 to 72 years who were treated with arsenic trioxide for relapsed or refractory APL. No overall differences in safety or effectiveness were observed between these patients and younger patients.

8.6 Renal Impairment Exposure of arsenic trioxide may be higher in patients with severe renal impairment [see Clinical Pharmacology (12.3) ] . Monitor patients with severe renal impairment (creatinine clearance [CL CR ] less than 30 mL/min) frequently for toxicity; a dose reduction may be warranted. The use of arsenic trioxide in patients on dialysis has not been studied.

8.7 Hepatic Impairment Since limited data are available across all hepatic impairment groups, caution is advised in the use of arsenic trioxide in patients with hepatic impairment [see Clinical Pharmacology (12.3) ] . Monitor patients with severe hepatic impairment (Child-Pugh Class C) frequently for toxicity.

The mechanism of action of arsenic trioxide is not completely understood. Arsenic trioxide causes morphological changes and DNA fragmentation characteristic of apoptosis in NB4 human promyelocytic leukemia cells in vitro . Arsenic trioxide also causes damage or degradation of the fusion protein promyelocytic leukemia (PML)-retinoic acid receptor (RAR)-alpha.