2.1 Chronic Lymphocytic Leukemia (CLL)

The oral dose of Oforta™ is different than the intravenous fludarabine phosphate dose.

The recommended adult dose of Oforta™ is 40 mg/m2 administered by mouth daily for five consecutive days. Each 5-day course of treatment should commence every 28 days. Dosage may be decreased or delayed based on evidence of hematologic or nonhematologic toxicity. Physicians should consider delaying or discontinuing the drug if neurotoxicity occurs. Oforta™ can be taken either on an empty stomach or with food. The tablets have to be swallowed whole with water; they should not be chewed or broken.

The following table provides guidance for determining the number of tablets of Oforta™ to be administered based on body surface area (BSA):

A number of clinical settings may predispose to increased toxicity from Oforta™. These include advanced age, renal insufficiency, and bone marrow impairment. Such patients should be monitored closely for excessive toxicity and the dose modified accordingly. The optimal duration of treatment has not been clearly established. It is recommended that three additional cycles of Oforta™ be administered following the achievement of a maximal response and then the drug should be discontinued.

2.2 Renal Impairment

• Reduce dose by 20% in patients with mild to moderate renal impairment (creatinine clearance 30 to 70 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]
• Reduce dose by 50% in patients with severe renal impairment (creatinine clearance < 30 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]

5.1 Neurotoxicity

Dose-dependent neurotoxicity has been observed with fludarabine phosphate. Dose levels approximately 4 times greater (96 mg/m2/day for 5 days to 7 days) than the recommended intravenous dose (25 mg/m2/day for 5 days) were associated with a syndrome characterized by delayed blindness, coma and death. Symptoms appeared from 21 days to 60 days following the last dose. Thirteen of 36 patients (36.1%) who received fludarabine phosphate intravenously at high doses (≥ 96 mg/m2/day for 5 days to 7 days per course) developed severe neurotoxicity, while only one of 443 patients (0.2%) who received the drug intravenously at low doses (≤ 40 mg/m2/day for 5 days per course) developed toxicity. In the pivotal clinical study conducted with Oforta™ administered at 40 mg/m2, severe impairment of consciousness was reported in one patient. The effect of chronic administration of fludarabine phosphate on the central nervous system is unknown; however, patients have received the recommended dose for up to 15 courses of therapy. Physicians should consider delaying or discontinuing the drug if neurotoxicity occurs.

5.2 Bone Marrow Suppression

Severe bone marrow suppression, notably anemia, thrombocytopenia and neutropenia, has been reported in patients treated with fludarabine phosphate. In a study in adult solid tumor patients, the median time to nadir counts was 13 days (range, 3 days to 25 days) for granulocytes and 16 days (range, 2 days to 32 days) for platelets. Most patients had hematologic impairment at baseline either as a result of disease or as a result of prior myelosuppressive therapy. Cumulative myelosuppression may be seen. While chemotherapy-induced myelosuppression is often reversible, administration of Oforta™ requires careful hematologic monitoring.

Several instances of trilineage bone marrow hypoplasia or aplasia resulting in pancytopenia, sometimes resulting in death, have been reported in adult patients. The duration of clinically significant cytopenia in the reported cases has ranged from approximately 2 months to approximately 1 year. These episodes have occurred both in previously treated or untreated patients. One case of pancytopenia was reported in the pivotal clinical study conducted with Oforta™.

Instances of life-threatening and sometimes fatal autoimmune hemolytic anemia have been reported to occur after one or more cycles of treatment with fludarabine phosphate in patients with or without a previous history of autoimmune hemolytic anemia or a positive Coombs' test and who may or may not be in remission from their disease. Steroids may or may not be effective in controlling these hemolytic episodes. The majority of patients rechallenged with fludarabine phosphate developed a recurrence in the hemolytic process. The mechanism(s) which predispose patients to the development of this complication has not been identified. Patients undergoing treatment with Oforta™ should be evaluated and closely monitored for hemolysis.

5.3 Pulmonary Toxicity

A high incidence of fatal pulmonary toxicity was observed in a clinical investigation using fludarabine phosphate in combination with pentostatin (deoxycoformycin) for the treatment of refractory chronic lymphocytic leukemia (CLL) in adults. Therefore, the use of Oforta™ in combination with pentostatin is not recommended.

5.4 Infections

Of 133 adult patients with CLL who received intravenous fludarabine phosphate in two clinical trials, there were 29 fatalities during study. Approximately 50% of the fatalities were due to infection and 25% due to progressive disease. Of 183 adult patients with CLL that received Oforta™ in two clinical trials, there were 13 deaths. Approximately 50% of the deaths were due to progressive disease, while two patient deaths (15%) were attributed to infection. Monitor for signs and symptoms of infection.

5.5 Tumor Lysis Syndrome

Tumor lysis syndrome associated with fludarabine phosphate treatment has been reported in patients with CLL with large tumor burdens. Since Oforta™ can induce a response as early as the first week of treatment, precautions should be taken in those patients at risk of developing this complication.

5.6 Use of Transfusions

Transfusion-associated graft-versus-host disease has been observed rarely after transfusion of non-irradiated blood in fludarabine phosphate treated patients. Consideration should, therefore, be given to the use of irradiated blood products in those patients requiring transfusions while undergoing treatment with Oforta™.

5.7 Renal Impairment

Oforta™ must be administered cautiously in patients with renal impairment. Following dosing of the intravenous product, the total body clearance of 2-fluoro-ara-A has been shown to be directly correlated with creatinine clearance. Patients with mild to moderate impairment of renal function (creatinine clearance 30 to 70 mL/min/1.73 m2) should have their Oforta™ dose reduced by 20% and be monitored closely. Patients with severe impairment of renal function (creatinine clearance < 30 mL/min/1.73 m2) should have their Oforta™ dose reduced by 50% and be monitored closely.

5.8 Monitoring

• Hematologic and Nonhematologic Toxicity
  Oforta™ is an antineoplastic agent with potentially significant toxic side effects. Patients undergoing therapy should be closely observed for signs of hematologic and nonhematologic toxicity. Periodic assessment of peripheral blood counts is recommended to detect the development of anemia, neutropenia and thrombocytopenia.
• Hematopoietic Suppression
  During treatment, the patient's hematologic profile (particularly neutrophils and platelets) should be monitored regularly to determine the degree of hematopoietic suppression.
• Infections
  Patients treated with Oforta™ appear to be at an increased risk of infection. Monitor for signs and symptoms of infection.

5.9 Pregnancy

Based on its mechanism of action, Oforta™ can cause fetal harm when administered to a pregnant woman. Fludarabine phosphate administered to rats and rabbits during organogenesis caused an increase in resorptions, skeletal and visceral malformation, and decreased fetal body weights. If Oforta™ is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus. Women of childbearing potential should be advised to avoid becoming pregnant. Women of childbearing potential and fertile males must take contraceptive measures during and at least for 6 months after the cessation of therapy.
[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 Oforta™ in 159 patients exposed to the drug. Oforta™ was studied primarily in Study 1 in 78 patients with CLL who received prior therapy and in Study 2 in 81 patients with CLL who had not received prior therapy.

Based on experience with the intravenous and oral use of fludarabine phosphate, the most common adverse reactions include myelosuppression (neutropenia, thrombocytopenia and anemia), fever and chills, infection, and nausea and vomiting. Other commonly reported events include malaise, fatigue, anorexia, and weakness. Serious opportunistic infections have occurred in patients with CLL treated with fludarabine phosphate. The most frequently reported adverse reactions and those reactions which are more clearly related to the drug, as reported in clinical studies conducted with intravenous and oral fludarabine phosphate, are arranged below according to body system.

6.2 Post Marketing Experience

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

7.1 Pentostatin

The use of Oforta™ in combination with pentostatin is not recommended due to the risk of severe pulmonary toxicity. [See Warnings and Precautions (5.6)]

8.1 Pregnancy

8.3 Nursing Mothers

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

8.4 Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

8.5 Geriatric Use

Of 78 previously treated patients with B-CLL treated with Oforta™ 50% were ≥ age 65 and 3% were ≥ age 75. The response rate was generally lower among patients age 65 and older. Among previously treated patients (Study 1) age 65 and older, the overall objective response, according to standardized response criteria developed by the National Cancer Institute CLL Working Group (NCI criteria), was 41%. The safety profile among younger and older patients on study was similar. Other reported clinical experience has not identified differences in responses or safety between older and younger patients.

8.6 Patients with Renal Impairment

In patients receiving intravenous fludarabine phosphate, the total body clearance of the metabolite 2-fluoro-ara-adenine (2F-ara-A) correlated with the creatinine clearance, indicating the importance of the renal excretion pathway for the elimination of the drug. Renal clearance represented approximately 40% of the total body clearance. Patients with mild to moderate renal impairment (30 to 70 mL/min/1.73 m2) receiving 20% reduced fludarabine phosphate dose had a similar exposure compared to patients with normal renal function receiving the recommended dose (AUC; 21 nM∙h/mL versus 20 nM∙h/mL). Two patients with severe renal impairment (< 30 mL/min/1.73 m2) receiving 40% reduced fludarabine phosphate dose had a 40% increase in exposure compared to patients with normal renal function receiving the recommended dose. The mean total body clearance was 172 mL/min for patients with normal renal function, 124 mL/min for patients with mild to moderately impaired renal function, and 71 mL/min for the two patients with severe renal impairment.

12.1 Mechanism of Action

Fludarabine phosphate (2F-ara-AMP) is a synthetic purine nucleotide antimetabolite agent. Upon administration, 2F-ara-AMP is rapidly dephosphorylated in the plasma to 2F-ara-A, which then enters into the cell. Intracellularly, 2F-ara-A is converted to the 5'-triphosphate, 2-fluoro-ara-ATP (2F-ara-ATP). 2F-ara-ATP competes with deoxyadenosine triphosphate for incorporation into DNA. Once incorporated into DNA, 2F-ara-ATP functions as a DNA chain terminator, inhibits DNA polymerase alpha, gamma, and delta, and inhibits ribonucleoside diphosphate reductase. 2F-ara-A also inhibits DNA primase and DNA ligase I. The mechanism of action of this antimetabolite is not completely characterized and may be multi-faceted.

12.2 Pharmacodynamics

Cardiac Electrophysiology

In a randomized, uncontrolled, open-label, parallel study, patients with B-cell CLL were administered a single dose of Oforta™ 40 mg/m2 (n = 42) or intravenous fludarabine phosphate 25 mg/m2 (n=14). The maximum increase in the baseline-corrected mean change in QTcI (individual-corrected QT interval) following treatment with Oforta™ was less than 10 milliseconds.

12.3 Pharmacokinetics

Studies with the intravenous product have demonstrated that fludarabine phosphate is converted to the active metabolite, 2F-ara-A. Clinical pharmacology studies have focused on 2F-ara-A pharmacokinetics.

Following administration of the intravenous product, systemic plasma clearance of 2F-ara-A is approximately 117 mL/min to 145 mL/min. After five daily 30 minute intravenous infusions of 25 mg 2F-ara- AMP/m2 to cancer patients, trough concentrations of 2F-ara-A increased by a factor of about 2. The terminal half-life of 2F-ara-A was approximately 20 hours. Plasma protein binding of 2F-ara-A was approximately 19% to 29%. A correlation was noted between the degree of absolute granulocyte count nadir and increased area under the concentration x time curve (AUC).

2F-ara-A exhibits dose proportional increases in AUC and Cmax after single oral doses of 50 mg, 70 mg or 90 mg of 2F-ara-AMP. Cmax of 2F-ara-A occurs 1 hour to 2 hours after single or multiple oral doses and is approximately 20 % to 30 % of the maximum plasma concentrations produced at the end of a 30 minute intravenous infusion of the same dose. The absolute oral bioavailability of 2F-ara-A is 50 – 65% following single and repeated doses of Oforta™. Similar systemic exposure (AUC) was observed after a single 40 mg/m2 Oforta™ and a single 25 mg/m2 fludarabine phosphate intravenous dose. The terminal half-life of 2F-ara-A was similar to that following intravenous administration; approximately 20 hours. The Cmax, AUC and terminal half-life of 2F-ara-A are unaffected when administered with a high fat meal, although Tmax is slightly delayed from 1.3 hours to 2.2 hours.

Following intravenous administration, renal clearance of 2F-ara-A represents approximately 40% of the total body clearance of fludarabine phosphate, and total body clearance is inversely correlated with serum creatinine and creatinine clearance. In two patients with median creatinine clearance of 22 mL/min/1.73 m2, 2F-ara-A clearance was reduced by 56%. Dosage adjustment based on creatinine clearance is recommended as follows:

Reduce dose by 20% in patients with mild to moderate renal impairment (creatinine clearance 30 to 70 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]

Reduce dose by 50% in patients with severe renal impairment (creatinine clearance < 30 mL/min/1.73 m2). [See Warnings and Precautions (5.7)]

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

No animal carcinogenicity studies with Oforta™ have been conducted.

Oforta™ is a clastogen.

Fludarabine phosphate was clastogenic in vitro to Chinese hamster ovary cells (chromosome aberration assay) in the presence of metabolic activation and induced sister chromatid exchanges both in the presence and absence of metabolic activation. In addition, fludarabine phosphate was clastogenic in vivo (mouse micronucleus assay) but was not mutagenic to germ cells (dominant lethal test in male mice). Fludarabine phosphate was not mutagenic to bacteria (Ames test) or mammalian cells either in the presence or absence of metabolic activation.

Studies in mice, rats and dogs have demonstrated dose-related adverse effects on the male reproductive system. Observations consisted of a decrease in mean testicular weights in mice and rats with a trend toward decreased testicular weights in dogs and degeneration and necrosis of spermatogenic epithelium of the testes in mice, rats and dogs.

STORAGE

Store under normal lighting conditions at 25°C (77°F); excursions permitted to 15–30°C (59–86°F) [see USP controlled room temperature].

HANDLING AND DISPOSAL

Procedures for proper handling and disposal should be considered. Consideration should be given to handling and disposal according to guidelines issued for cytotoxic drugs. Several guidelines on this subject have been published.1–4 Caution should be exercised in the handling of Oforta™. Push tablets through foil to open. Do not remove tablets from individual blisters until immediately prior to taking or administering each scheduled dose. Do not crush tablets. Avoid exposure by direct contact of the skin or mucous membranes or by inhalation. If contact occurs, wash thoroughly with soap and water or wash the eyes immediately with gently flowing water for at least 15 minutes. Consult healthcare provider in case of a skin reaction or if the drug gets in the eyes.

17.1 Bone Marrow Suppression

Inform patients that Oforta™ decreases blood cell counts such as white blood cells, platelets, and red blood cells. Thus, it is important that periodic assessment of their blood count be performed to detect the development of neutropenia, thrombocytopenia and anemia. [See Warnings and Precautions (5.2)]

17.2 Infections

Instruct patients to notify their physician promptly if fever or other signs of infection such as chills, cough, or burning pain on urination occurs while on therapy. [See Warnings and Precautions (5.4)]

17.3 Pregnancy

Women of childbearing potential and fertile males must take contraceptive measures during and at least for 6 months after the cessation of therapy. Oforta™ may cause fetal harm when administered to a pregnant woman. [See Warnings and Precautions (5.9)]

17.4 Handling and Disposal

Instruct patients that caution should be exercised in the handling of Oforta™. Do not crush tablets. Avoid exposure by direct contact of the skin or mucous membranes or by inhalation. If contact occurs, wash thoroughly with soap and water or wash the eyes immediately with gently flowing water for at least 15 minutes. Consult healthcare provider in case of a skin reaction or if the drug gets in the eyes. Ask your healthcare provider or pharmacist for directions about how to safely dispose of Oforta™.