Busulfan

1 INDICATIONS AND USAGE Busulfan injection is indicated for use in combination with cyclophosphamide as a conditioning regimen prior to allogeneic hematopoietic progenitor cell transplantation for chronic myelogenous leukemia. Busulfan injection is an alkylating drug indicated for: Use in combination with cyclophosphamide as a conditioning regimen prior to allogeneic hematopoietic progenitor cell transplantation for chronic myelogenous leukemia (CML) ( 1 )

12.1 Mechanism of Action Busulfan is a bifunctional alkylating agent in which two labile methanesulfonate groups are attached to opposite ends of a four-carbon alkyl chain. In aqueous media, busulfan hydrolyzes to release the methanesulfonate groups. This produces reactive carbonium ions that can alkylate DNA. DNA damage is thought to be responsible for much of the cytotoxicity of busulfan.

2 DOSAGE AND ADMINISTRATION Pre-medicate with anticonvulsants (e.g. benzodiazepines, phenytoin, valproic acid or levetiracetam) and antiemetic ( 2.1 , 5.2 ) Dilute and administer as intravenous infusion. Do not administer as intravenous push or bolus ( 2.1 , 2.3 ) Recommended adult dose: 0.8 mg per kg of ideal body weight or actual body weight, whichever is lower, administered intravenously via a central venous catheter as a two-hour infusion every six hours for four consecutive days for a total of 16 doses ( 2.1 ) 2.1 Initial Dosing Information • Administer busulfan injection in combination with cyclophosphamide as a conditioning regimen prior to bone marrow or peripheral blood progenitor cell replacement. For patients weighing more than 12 kg, the recommended doses are: o Busulfan injection 0.8 mg per kg (ideal body weight or actual body weight, whichever is lower) intravenously via a central venous catheter as a two-hour infusion every six hours for four consecutive days for a total of 16 doses (Days -7, -6, -5 and -4). o Cyclophosphamide 60 mg per kg intravenously as a one-hour infusion on each of two days beginning no sooner than six hours following the 16 th dose of busulfan injection (Days -3 and -2). o Administer hematopoietic progenitor cells on Day 0. • Premedicate patients with anticonvulsants (e.g., benzodiazepines, phenytoin, valproic acid or levetiracetam) to prevent seizures reported with the use of high dose busulfan injection. Administer anticonvulsants 12 hours prior to busulfan injection to 24 hours after the last dose of busulfan injection [see Warnings and Precautions (5.2) ]. • Administer antiemetics prior to the first dose of busulfan injection and continue on a fixed schedule through busulfan injection administration. • Busulfan injection clearance is best predicted when the busulfan injection dose is administered based on adjusted ideal body weight. Dosing busulfan injection based on actual body weight, ideal body weight or other factors can produce significant differences in busulfan injection clearance among lean, normal and obese patients. o Calculate ideal body weight (IBW) as follows (height in cm and weight in kg): Men: IBW (kg) = 50+0.91x (height in cm -152) Women: IBW (kg) = 45+0.91x (height in cm -152) o For obese or severely obese patients, base busulfan injection dosing on adjusted ideal body weight (AIBW): AIBW= IBW + 0.25x (actual weight -IBW). 2.2 Preparation and Administration Precautions Busulfan injection is incompatible with polycarbonate. Do not use any infusion components (syringes, filter needles, intravenous tubing, etc.) containing polycarbonate with busulfan injection. Use an administration set with minimal residual hold-up volume (2 mL to 5 mL) for product administration. Busulfan injection is a cytotoxic drug. Follow applicable special handling and disposal procedures. Skin reactions may occur with accidental exposure. Use gloves when preparing busulfan injection. If busulfan injection or diluted busulfan injection solution contacts the skin or mucosa, wash the skin or mucosa thoroughly with water. Visually inspect parenteral drug products for particulate matter and discoloration prior to administration whenever the solution and container permit. Do not use if particulate matter is seen in the busulfan injection vial. 2.3 Preparation for Intravenous Administration Busulfan injection must be diluted prior to intravenous infusion with either 0.9% Sodium Chloride Injection, USP (normal saline) or 5% Dextrose Injection, USP (D5W). The diluent quantity should be 10 times the volume of busulfan injection, so that the final concentration of busulfan is approximately 0.5 mg per mL. Calculation of the dose for a 70 kg patient would be performed as follows: (70 kg patient) x (0.8 mg per kg) ÷ (6 mg per mL) = 9.3 mL busulfan injection (56 mg total dose). To prepare the final solution for infusion, add 9.3 mL of busulfan injection to 93 mL of diluent (normal saline or D5W) as calculated b

6 ADVERSE REACTIONS The following adverse reactions are discussed in more detail in other sections of the labeling: Myelosuppression [see Warnings and Precautions (5.1) ] Seizures [see Warnings and Precautions (5.2) ] Hepatic Veno-Occlusive Disease (HVOD) [see Warnings and Precautions (5.3) ] Embryo-fetal Toxicity [see Warnings and Precautions (5.4) ] Cardiac Tamponade [see Warnings and Precautions (5.5) ] Bronchopulmonary Dysplasia [see Warnings and Precautions (5.6) ] Cellular Dysplasia [see Warnings and Precautions (5.7) ] Most common adverse reactions (incidence >60%) were: myelosuppression, nausea, stomatitis, vomiting, anorexia, diarrhea, insomnia, fever, hypomagnesemia, abdominal pain, anxiety, headache, hyperglycemia and hypokalemia ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Eugia US LLC at 1-866-850-2876 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. Adverse reaction information is primarily derived from the clinical study (N=61) of busulfan and the data obtained for high-dose oral busulfan conditioning in the setting of randomized, controlled trials identified through a literature review. In the busulfan injection allogeneic stem cell transplantation clinical trial, all patients were treated with busulfan 0.8 mg per kg as a two-hour infusion every six hours for 16 doses over four days, combined with cyclophosphamide 60 mg per kg x2 days. Ninety-three percent (93%) of evaluable patients receiving this dose of busulfan maintained an AUC less than 1,500 µM•min for dose 9, which has generally been considered the level that minimizes the risk of HVOD. Table 1 lists the non-hematologic adverse reactions events through Bone Marrow Transplantation (BMT) Day +28 at a rate greater than or equal to 20% in patients treated with busulfan prior to allogeneic hematopoietic cell transplantation. Table 1: Summary of the Incidence (greater than or equal to 20%) of Non-Hematologic Adverse Reactions through BMT Day +28 in Patients who Received Busulfan Prior to Allogeneic Hematopoietic Progenitor Cell Transplantation 1. Includes all reported adverse reactions regardless of severity (toxicity grades 1 to 4) Non-Hematological Adverse Reactions 1 Percent Incidence BODY AS A WHOLE Fever 80 Headache 69 Asthenia 51 Chills 46 Pain 44 Edema General 28 Allergic Reaction 26 Chest Pain 26 Inflammation at Injection Site 25 Back Pain 23 CARDIOVASCULAR SYSTEM Tachycardia 44 Hypertension 36 Thrombosis 33 Vasodilation 25 DIGESTIVE SYSTEM Nausea 98 Stomatitis (Mucositis) 97 Vomiting 95 Anorexia 85 Diarrhea 84 Abdominal Pain 72 Dyspepsia 44 Constipation 38 Dry Mouth 26 Rectal Disorder 25 Abdominal Enlargement 23 METABOLIC AND NUTRITIONAL SYSTEM Hypomagnesemia 77 Hyperglycemia 66 Hypokalemia 64 Hypocalcemia 49 Hyperbilirubinemia 49 Edema 36 SGPT Elevation 31 Creatinine Increased 21 NERVOUS SYSTEM Insomnia 84 Anxiety 72 Dizziness 30 Depression 23 RESPIRATORY SYSTEM Rhinitis 44 Lung Disorder 34 Cough 28 Epistaxis 25 Dyspnea 25 SKIN AND APPENDAGES Rash 57 Pruritus 28 Additional Adverse Reactions by Body System Hematologic : Prolonged prothrombin time Gastrointestinal: Esophagitis, ileus, hematemesis, pancreatitis, rectal discomfort Hepatic: Alkaline phosphatase increases, jaundice, hepatomegaly Graft-versus-host disease: Graft-versus-host disease. There were 3 deaths (5%) attributed to GVHD. Edema: Hypervolemia, or documented weight increase Infection: Infection, pneumonia (fatal in one patient and life-threatening in 3% of patients) Cardiovascular: Arrhythmia, atrial fibrillation, ventricular extrasystoles, third degree heart block, thrombosis (all episodes were associated with the central venous catheter), hypotension, flushing and hot flashes, cardio

5 WARNINGS AND PRECAUTIONS Seizures: Initiate anticonvulsant prophylactic therapy prior to treatment with busulfan. Monitor patients with history of seizure disorder, head trauma or receiving epileptogenic drugs ( 5.2 ) Hepatic Veno-Occlusive Disease (HVOD): Increased risk of developing HVOD at AUC greater than 1,500 µM·min. Monitor serum transaminases, alkaline phosphatase and bilirubin daily ( 5.3 ) Embryo-fetal Toxicity: Can cause fetal harm. Advise of potential risk to a fetus and use of effective contraception ( 5.4 , 8.1 , 8.3 ) Cardiac tamponade has been reported in pediatric patients with thalassemia who received high doses of oral busulfan and cyclophosphamide. Abdominal pain and vomiting preceded the tamponade in most patients ( 5.5 ) 5.1 Myelosuppression The most frequent serious consequence of treatment with busulfan at the recommended dose and schedule is prolonged myelosuppression, occurring in all patients (100%). Severe granulocytopenia, thrombocytopenia, anemia, or any combination thereof may develop. Hematopoietic progenitor cell transplantation is required to prevent potentially fatal complications of the prolonged myelosuppression. Monitor complete blood counts, including white blood cell differentials, and quantitative platelet counts daily during treatment and until engraftment is demonstrated . Absolute neutrophil counts dropped below 0.5x10 9 /L at a median of 4 days post-transplant in 100% of patients treated in the busulfan clinical trial. The absolute neutrophil count recovered at a median of 13 days following allogeneic transplantation when prophylactic filgrastim was used in the majority of patients. Thrombocytopenia (less than 25,000/mm 3 or requiring platelet transfusion) occurred at a median of 5 to 6 days in 98% of patients. Anemia (hemoglobin less than 8.0 g/dL) occurred in 69% of patients. Use antibiotic therapy and platelet and red blood cell support when medically indicated. 5.2 Seizures Seizures have been reported in patients receiving high-dose oral busulfan at doses producing plasma drug levels similar to those achieved following the recommended dosage of busulfan. Despite prophylactic therapy with phenytoin, one seizure (1/42 patients) was reported during an autologous transplantation clinical trial of busulfan. This episode occurred during the cyclophosphamide portion of the conditioning regimen, 36 hours after the last busulfan dose. Initiate phenytoin therapy or any other alternative anti-convulsant prophylactic therapy (e.g., benzodiazepines, valproic acid or levetiracetam) prior to busulfan treatment [see Dosage and Administration (2.1) ]. Use caution when administering the recommended dose of busulfan to patients with a history of a seizure disorder or head trauma or who are receiving other potentially epileptogenic drugs. 5.3 Hepatic Veno-Occlusive Disease (HVOD) Current literature suggests that high busulfan area under the plasma concentration verses time curve (AUC) values (greater than 1,500 µM•min) may be associated with an increased risk of developing HVOD. Patients who have received prior radiation therapy, greater than or equal to three cycles of chemotherapy, or a prior progenitor cell transplant may be at an increased risk of developing HVOD with the recommended busulfan dose and regimen. Based on clinical examination and laboratory findings, HVOD was diagnosed in 8% (5/61) of patients treated with busulfan in the setting of allogeneic transplantation, was fatal in 2/5 cases (40%), and yielded an overall mortality from HVOD in the entire study population of 2/61 (3%). Three of the five patients diagnosed with HVOD were retrospectively found to meet the Jones’ criteria. The incidence of HVOD reported in the literature from the randomized, controlled trials was 7.7% to 12% [see Clinical Studies (14) ]. Monitor serum transaminases, alkaline phosphatase, and bilirubin daily through BMT Day +28 to detect hepatotoxicity, which may herald the onset of HVOD . 5.4 Embryo-fetal To

4 CONTRAINDICATIONS Busulfan is contraindicated in patients with a history of hypersensitivity to any of its components. Busulfan is contraindicated in patients with a history of hypersensitivity to any of its components ( 4 )

10 OVERDOSAGE There is no known antidote to busulfan other than hematopoietic progenitor cell transplantation. In the absence of hematopoietic progenitor cell transplantation, the recommended dosage for busulfan would constitute an overdose of busulfan. The principal toxic effect is profound bone marrow hypoplasia/aplasia and pancytopenia, but the central nervous system, liver, lungs, and gastrointestinal tract may be affected. Monitor hematologic status closely and institute vigorous supportive measures as medically indicated. Survival after a single 140 mg dose of Myleran ® Tablets in an 18 kg, 4-year old child has been reported. Inadvertent administration of a greater than normal dose of oral busulfan (2.1 mg per kg; total dose of 23.3 mg per kg) occurred in a 2-year old child prior to a scheduled bone marrow transplant without sequelae. An acute dose of 2.4 g was fatal in a 10-year old boy. There is one report that busulfan is dialyzable, thus dialysis should be considered in the case of overdose.