2.1 Recommended Dosage

Administer the recommended pediatric dose of 52 mg/m 2as an intravenous infusion over 2 hours daily for 5 consecutive days.

• Repeat treatment cycles following recovery or return to baseline organ function, approximately every 2 to 6 weeks. Base dosage on the patient's body surface area (BSA), calculated using the actual height and weight before the start of each cycle. To prevent drug incompatibilities, do not administer other medications through the same intravenous line. Administer subsequent cycles no sooner than 14 days from the starting day of the previous cycle and provided the patient's ANC is ≥0.75 × 10 9/L.
• Provide supportive care, such as intravenous fluids, antihyperuricemic treatment, and alkalinize urine throughout the 5 days of clofarabine administration to reduce the effects of tumor lysis and other adverse reactions.
• Discontinue clofarabine if hypotension develops during the 5 days of administration.
• Monitor renal and hepatic function during the 5 days of clofarabine administration [see Warnings and Precautions (5.7, 5.8)] .
• Monitor patients taking medications known to affect blood pressure. Monitor cardiac function during administration of clofarabine.

2.2 Recommended Dosage Reduction for Renal Impairment

• Reduce the dose by 50% in patients with creatinine clearance (CrCL) between 30 and 60 mL/min. There is insufficient information to make a dosage recommendation in patients with CrCL less than 30 mL/min [see Use in Specific Populations (8.7)] .

2.3 Potential Concomitant Medications and Medications to Avoid

• Consider prophylactic antiemetic medications as clofarabine is moderately emetogenic.
• Consider the use of prophylactic steroids to mitigate Systemic Inflammatory Response Syndrome (SIRS) or capillary leak syndrome (e.g., hypotension, tachycardia, tachypnea, and pulmonary edema).
• Minimize exposure to drugs with known renal toxicity during the 5 days of clofarabine administration since the risk of renal toxicity may be increased.
• Avoid concomitant use of medications known to induce hepatic toxicity.

2.4 Dose Modifications and Reinitiation of Therapy after Adverse Reactions

2.5 Reconstitution/Preparation

Filter clofarabine through a sterile 0.2 micron syringe filter and then dilute with 5% Dextrose Injection, USP, or 0.9% Sodium Chloride Injection, USP, prior to intravenous infusion to a final concentration between 0.15 mg/mL and 0.4 mg/mL. Use within 24 hours of preparation. Store diluted clofarabine at room temperature (15°C to 30°C).

Discard unused portion in vial.

5.1 Myelosuppression

Clofarabine causes myelosuppression which may be severe and prolonged. Febrile neutropenia occurred in 55% and non-febrile neutropenia in an additional 10% of pediatric patients in clinical trials. At initiation of treatment, most patients in the clinical studies had hematological impairment as a manifestation of leukemia. Myelosuppression is usually reversible with interruption of clofarabine treatment and appears to be dose-dependent. Monitor complete blood counts [see Dosage and Administration (2.4)] .

5.2 Hemorrhage

Serious and fatal hemorrhage, including cerebral, gastrointestinal and pulmonary hemorrhage, has occurred. The majority of the cases were associated with thrombocytopenia. Monitor platelets and coagulation parameters and treat accordingly [see Adverse Reactions (6.2)] .

5.3 Infections

Clofarabine increases the risk of infection, including severe and fatal sepsis, and opportunistic infections. At baseline, 48% of the pediatric patients had one or more concurrent infections. A total of 83% of patients experienced at least one infection after clofarabine treatment, including fungal, viral and bacterial infections. Monitor patients for signs and symptoms of infection, discontinue clofarabine, and treat promptly.

5.4 Tumor Lysis Syndrome

Administration of clofarabine may result in tumor lysis syndrome associated with the break-down metabolic products from peripheral leukemia cell death. Monitor patients undergoing treatment for signs and symptoms of tumor lysis syndrome and initiate preventive measures including adequate intravenous fluids and measures to control uric acid.

5.5 Systemic Inflammatory Response Syndrome (SIRS) and Capillary Leak Syndrome

Clofarabine may cause a cytokine release syndrome (e.g., tachypnea, tachycardia, hypotension, pulmonary edema) that may progress to the systemic inflammatory response syndrome (SIRS) with capillary leak syndrome and organ impairment which may be fatal. Monitor patients frequently for these conditions. In clinical trials, SIRS was reported in two patients (2%); capillary leak syndrome was reported in four patients (4%). Symptoms included rapid onset of respiratory distress, hypotension, pleural and pericardial effusion, and multiorgan failure. Close monitoring for this syndrome and early intervention may reduce the risk. Immediately discontinue clofarabine and provide appropriate supportive measures. The use of prophylactic steroids (e.g., 100 mg/m 2hydrocortisone on Days 1 through 3) may be of benefit in preventing signs or symptoms of SIRS or capillary leak syndrome. Consider use of diuretics and/or albumin. After the patient is stabilized and organ function has returned to baseline, retreatment with clofarabine can be considered with a 25% dose reduction.

5.6 Venous Occlusive Disease of the Liver

Patients who have previously received a hematopoietic stem cell transplant (HSCT) are at higher risk for veno-occlusive disease (VOD) of the liver following treatment with clofarabine (40 mg/m 2) when used in combination with etoposide (100 mg/m 2) and cyclophosphamide (440 mg/m 2). Severe hepatotoxic events have been reported in a combination study of clofarabine in pediatric patients with relapsed or refractory acute leukemia. Two cases (2%) of VOD in the monotherapy studies were considered related to study drug. Monitor for and discontinue clofarabine if VOD is suspected.

5.7 Hepatotoxicity

Severe and fatal hepatotoxicity, including hepatitis and hepatic failure, has occurred with the use of clofarabine. In clinical studies, Grade 3–4 liver enzyme elevations were observed in pediatric patients during treatment with clofarabine at the following rates: elevated aspartate aminotransferase (AST) occurred in 36% of patients; elevated alanine aminotransferase (ALT) occurred in 44% of patients. AST and ALT elevations typically occurred within 10 days of clofarabine administration and returned to Grade 2 or less within 15 days. Grade 3 or 4 elevated bilirubin occurred in 13% of patients, with 2 events reported as Grade 4 hyperbilirubinemia (2%), one of which resulted in treatment discontinuation and one patient had multiorgan failure and died. Eight patients (7%) had Grade 3 or 4 elevations in serum bilirubin at the last time point measured; these patients died due to sepsis and/or multiorgan failure. Monitor hepatic function, and for signs and symptoms of hepatitis and hepatic failure. Discontinue clofarabine immediately for Grade 3 or greater liver enzyme and/or bilirubin elevations [see Dosage and Administration (2.4)] .

5.8 Renal Toxicity

Clofarabine may cause acute renal failure. In clofarabine treated patients in clinical studies, Grade 3 or 4 elevated creatinine occurred in 8% of patients and acute renal failure was reported as Grade 3 in three patients (3%) and Grade 4 in two patients (2%). Patients with infection, sepsis, or tumor lysis syndrome may be at increased risk of renal toxicity when treated with clofarabine. Hematuria occurred in 13% of clofarabine treated patients overall. Monitor patients for renal toxicity and interrupt or discontinue clofarabine as necessary [see Dosage and Administration (2.4)] .

5.9 Enterocolitis

Fatal and serious cases of enterocolitis, including neutropenic colitis, cecitis, and C difficilecolitis, have occurred during treatment with clofarabine. This has occurred more frequently within 30 days of treatment, and in the setting of combination chemotherapy. Enterocolitis may lead to necrosis, perforation, hemorrhage or sepsis complications. Monitor patients for signs and symptoms of enterocolitis and treat promptly.

5.10 Skin Reactions

Serious and fatal cases of Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) have been reported. Discontinue clofarabine for exfoliative or bullous rash, or if SJS or TEN is suspected [see Adverse Reactions (6.2)] .

5.11 Embryo-Fetal Toxicity

Based on findings from animal reproductive studies and the drug's mechanism of action, clofarabine can cause fetal harm when administered to a pregnant woman. Intravenous doses of clofarabine in rats and rabbits administered during organogenesis at doses that were below the maximum recommended human dose of 52 mg/m 2based on body surface area (mg/m 2) caused an increase in resorptions, malformations, and variations. Advise females of reproductive potential of the potential risk to a fetus and to use an effective method of contraception during treatment with clofarabine and for at least 6 months after the last dose. Advise males with female partners of reproductive potential to use effective contraception during treatment with clofarabine and for at least 3 months after the last dose [see Use in Specific Populations (8.1)] .

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.

The data described below reflect exposure to clofarabine in 115 pediatric patients with relapsed or refractory Acute Lymphoblastic Leukemia (ALL) (70 patients) or Acute Myelogenous Leukemia (AML) (45 patients).

In total, 115 pediatric patients treated in clinical trials received the recommended dose of clofarabine 52 mg/m 2daily × 5. The median number of cycles was 2. The median cumulative amount of clofarabine received by pediatric patients during all cycles was 540 mg.

Most common adverse reactions (≥25%): vomiting, nausea, diarrhea, febrile neutropenia, pruritus, headache, bacteremia, pyrexia, rash, tachycardia, abdominal pain, chills, fatigue, anorexia, pain in extremity, hypotension, epistaxis, and petechiae.

Table 1 lists adverse reactions by System Organ Class, including severe or life-threatening (NCI CTCAE Grade 3 or Grade 4), reported in ≥5% of the 115 patients in the 52 mg/m 2/day dose group (pooled analysis of pediatric patients with ALL and AML). More detailed information and follow-up of certain events is given below.

The following adverse reactions were reported in <5% of the 115 pediatric patients with ALL or AML:

Gastrointestinal Disorders:cecitis, pancreatitis

Hepatobiliary Disorders:hyperbilirubinemia

Immune System Disorders:hypersensitivity

Infections and Infestations:bacterial infection, Enterococcal bacteremia, Escherichia bacteremia, Escherichia sepsis, fungal infection, fungal sepsis, gastroenteritis adenovirus, infection, influenza, parainfluenza virus infection, pneumonia fungal, pneumonia primary atypical, Respiratory syncytial virus infection, sinusitis, staphylococcal infection

Investigations:blood creatinine increased

Psychiatric Disorders:mental status change

Respiratory, Thoracic and Mediastinal Disorder:pulmonary edema

Table 2 lists the incidence of treatment-emergent laboratory abnormalities after clofarabine administration at 52 mg/m 2among pediatric patients with ALL and AML (N=115).

6.2 Postmarketing Experience

The following adverse reactions have been identified during postapproval use of clofarabine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

• Gastrointestinal disorders: gastrointestinal hemorrhage including fatalities.
• Metabolism and nutrition disorders: hyponatremia
• Skin and subcutaneous tissue disorders: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN) (including fatal cases).

8.1 Pregnancy

8.2 Lactation

8.3 Females and Males of Reproductive Potential

8.4 Pediatric Use

Safety and effectiveness have been established in pediatric patients 1 to 21 years old with relapsed or refractory acute lymphoblastic leukemia.

8.5 Geriatric Use

Safety and effectiveness of clofarabine has not been established in geriatric patients aged 65 and older.

8.6 Adults with Hematologic Malignancies

Safety and effectiveness have not been established in adults.

8.7 Renal Impairment

Reduce the clofarabine starting dose by 50% in patients with CrCL of 30 to 60 mL/min. There is insufficient information to make a dosage recommendation in patients with CrCL less than 30 mL/min or in patients on dialysis.

The pharmacokinetics of clofarabine in patients with renal impairment and normal renal function were obtained from a population pharmacokinetic analysis of three pediatric and two adult studies. In patients with CrCL 60 to less than 90 mL/min (N=47) and CrCL 30 to less than 60 mL/min (N=30), the average AUC of clofarabine increased by 60% and 140%, respectively, compared to patients with normal (N=66) renal function (CrCL greater than 90 mL/min).

12.1 Mechanism of Action

Clofarabine is sequentially metabolized intracellularly to the 5ʹ-monophosphate metabolite by deoxycytidine kinase and mono- and di-phospho-kinases to the active 5ʹ-triphosphate metabolite. Clofarabine has affinity for the activating phosphorylating enzyme, deoxycytidine kinase, equal to or greater than that of the natural substrate, deoxycytidine. Clofarabine inhibits DNA synthesis by decreasing cellular deoxynucleotide triphosphate pools through an inhibitory action on ribonucleotide reductase, and by terminating DNA chain elongation and inhibiting repair through incorporation into the DNA chain by competitive inhibition of DNA polymerases. The affinity of clofarabine triphosphate for these enzymes is similar to or greater than that of deoxyadenosine triphosphate. In preclinical models, clofarabine has demonstrated the ability to inhibit DNA repair by incorporation into the DNA chain during the repair process. Clofarabine 5ʹ-triphosphate also disrupts the integrity of mitochondrial membrane, leading to the release of the pro-apoptotic mitochondrial proteins, cytochrome C and apoptosis-inducing factor, leading to programmed cell death.

Clofarabine is cytotoxic to rapidly proliferating and quiescent cancer cell types in vitro.

12.3 Pharmacokinetics

The population pharmacokinetics of clofarabine were studied in 40 pediatric patients aged 2 to 19 years (21 males/19 females) with relapsed or refractory acute lymphoblastic leukemia (ALL) or acute myelogenous leukemia (AML). At the given 52 mg/m 2dose, similar concentrations were obtained over a wide range of body surface areas (BSAs). Clofarabine was 47% bound to plasma proteins, predominantly to albumin. Based on non-compartmental analysis, systemic clearance and volume of distribution at steady-state were 28.8 L/h/m 2and 172 L/m 2, respectively. The terminal half-life was 5.2 hours. No apparent difference in pharmacokinetics was observed between patients with ALL and AML or between males and females.

No relationship between clofarabine or clofarabine triphosphate exposure and toxicity or response was found in this population.

Based on 24-hour urine collections in the pediatric studies, 49% to 60% of the dose is excreted in the urine unchanged. In vitrostudies using isolated human hepatocytes indicate very limited metabolism (0.2%). The pathways of non-hepatic elimination remain unknown.

Clofarabine has not been studied in patients with hepatic impairment.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Clofarabine has not been tested for carcinogenic potential.

Clofarabine was clastogenic in the in vitromammalian cell chromosome aberration assay (CHO cells) and in the in vivorat micronucleus assay. Clofarabine was not mutagenic in the bacterial mutation assay (Ames test).

Studies in mice, rats, and dogs have demonstrated dose-related adverse effects on male reproductive organs. Seminiferous tubule and testicular degeneration and atrophy were reported in male mice receiving intraperitoneal doses of 3 mg/kg/day (approximately 0.2-times the recommended human dose based on body surface area [BSA]). Rats receiving 25 mg/kg/day (approximately 3-times the recommended human dose based on BSA) in a 6-month intravenous study had testicular findings of bilateral degeneration of the seminiferous epithelium with retained spermatids and atrophy of interstitial cells. In a 6-month intravenous dog study, cell degeneration of the epididymis and degeneration of the seminiferous epithelium in the testes were observed at 0.375 mg/kg/day (approximately 0.1-times the recommended human dose on a BSA basis). Ovarian atrophy or degeneration and uterine mucosal apoptosis were observed in female mice at 75 mg/kg/day (approximately 4-times the recommended human dose on a mg/m 2basis), the only dose administered to female mice.

Dose Escalation Study in Pediatric Patients with Hematologic Malignancies

The safety and efficacy of clofarabine were evaluated in pediatric patients with refractory or relapsed hematologic malignancies in an open-label, dose-escalation, noncomparative study (NCT00042341, A Phase II, Open Label Study of Clofarabine in Pediatric Patients With Refractory or Relapsed Acute Lymphoblastic Leukemia). The starting dose of clofarabine was 11.25 mg/m 2/day intravenous infusion daily × 5 and escalated to 70 mg/m 2/day intravenous infusion daily × 5. This dosing schedule was repeated every 2 to 6 weeks depending on toxicity and response. Nine of 17 ALL patients were treated with clofarabine 52 mg/m 2daily for 5 days. In the 17 ALL patients there were 2 complete remissions (12%) and 2 partial remissions (12%) at varying doses. Dose-limiting toxicities in this study were reversible hyperbilirubinemia and elevated transaminase levels and skin rash, experienced at 70 mg/m 2. As a result of this study, the recommended dose for subsequent study in pediatric patients was determined to be 52 mg/m 2/day for 5 days.

Single-Arm Study in Pediatric ALL

Clofarabine was evaluated in an open-label, single-arm study of 61 pediatric patients with relapsed/refractory ALL. Patients received a dose of 52 mg/m 2intravenous infusion over 2 hours for 5 consecutive days repeated every 2 to 6 weeks for up to 12 cycles. There was no dose escalation in this study.

All patients had disease that had relapsed after and/or was refractory to two or more prior therapies. Most patients, 38/61 (62%), had received >2 prior regimens and 18/61 (30%) of the patients had undergone at least 1 prior transplant. The median age of the treated patients was 12 years, 61% were male, 39% were female, 44% were Caucasian, 38% were Hispanic, 12% were African-American, 2% were Asian and 5% were Other race.

The overall remission (OR) rate (Complete Remission [CR] + CR in the absence of total platelet recovery [CRp]) was evaluated. CR was defined as no evidence of circulating blasts or extramedullary disease, an M1 bone marrow (≤5% blasts), and recovery of peripheral counts [platelets ≥100 × 10 9/L and absolute neutrophil count (ANC) ≥1× 10 9/L]. CRp was defined as meeting all criteria for CR except for recovery of platelet counts to ≥100 × 10 9/L. Partial Response (PR) was also determined, defined as complete disappearance of circulating blasts, an M2 bone marrow (≥5% and ≤25% blasts), and appearance of normal progenitor cells or an M1 marrow that did not qualify for CR or CRp. Duration of remission was also evaluated. Transplantation rate was not a study endpoint.

Response rates for these studies were determined by an unblinded Independent Response Review Panel (IRRP).

Table 3 summarizes results for the pediatric ALL study. Responses were seen in both pre-B and T-cell immunophenotypes of ALL. The median cumulative dose was 530 mg (range 29–2815 mg) in 1 (41%), 2 (44%) or 3 or more (15%) cycles. The median number of cycles was 2 (range 1–12). The median time between cycles was 28 days with a range of 12 to 55 days.

Six (9.8%) patients achieved a PR; the clinical relevance of a PR in this setting is unknown.

Of 35 patients who were refractory to their immediately preceding induction regimen, 6 (17%) achieved a CR or CRp. Of 18 patients who had at least 1 prior hematopoietic stem cell transplant (HSCT), 5 (28%) achieved a CR or CRp.

Among the 12 patients who achieved at least a CRp, 6 patients achieved the best response after 1 cycle of clofarabine, 5 patients required 2 courses and 1 patient achieved a CR after 3 cycles of therapy.

Vials containing undiluted clofarabine should be stored at 25°C (77°F); excursions permitted to 15°C to 30°C (59°F to 86°F). Do not freeze. Retain in carton until contents are used.

Clofarabine is a cytotoxic drug. Follow applicable special handling and disposal procedures. 1

Hematologic Toxicity

Advise patients to return for regular blood counts and to report any symptoms associated with hematologic toxicity (such as weakness, fatigue, pallor, shortness of breath, easy bruising, petechiae, purpura, fever) to their physician [see Warnings and Precautions (5.1)] .

Infection

Advise patients of the signs or symptoms of infection (e.g., fever) and report to the physician immediately if any occur [see Warnings and Precautions (5.3)] .

Hepatic and Renal Toxicity

Advise patients to avoid medications including over the counter and herbal medications, which may be hepatotoxic or nephrotoxic, during the 5 days of clofarabine administration. Also, advise patients of the possibility of developing liver function abnormalities and to immediately report signs or symptoms of jaundice. Advise patients of the signs or symptoms of renal failure/acute renal failure [see Warnings and Precautions (5.7, 5.8)] .

Systemic Inflammatory Response Syndrome (SIRS)/Capillary Leak Syndrome

Advise patients of the signs or symptoms of SIRS, such as fever, tachycardia, tachypnea, dyspnea and symptoms suggestive of hypotension [see Warnings and Precautions (5.5)] .

Pregnancy

Advise pregnant women and females of reproductive potential of the potential risk to a fetus. Advise females to inform their healthcare provider of a known or suspected pregnancy [see Warnings and Precautions (5.11), Use in Specific Populations (8.3)] . Advise female patients of reproductive potential to use effective contraception during treatment with clofarabine and for at least 6 months after the last dose [see Use in Specific Populations (8.3)] . Advise males with female partners of reproductive potential to use effective contraception during treatment with clofarabine and for at least 3 months after the last dose [see Use in Specific Populations (8.3), Nonclinical Toxicology (13.1)] .

Lactation

Advise females not to breastfeed during treatment with clofarabine and for 2 weeks after the last dose [see Use in Specific Populations (8.2)] .

Gastrointestinal Disorders

Advise patients that they may experience nausea, vomiting, and/or diarrhea with clofarabine. If these symptoms are significant, they should seek medical attention [see Warnings and Precautions (5.9)] .

Rash

Advise patients that they may experience skin rash with clofarabine. If this symptom is significant, they should seek medical attention.