Gemcitabine hydrochloride

Gemcitabine in combination with carboplatin is indicated for the treatment of patients with advanced ovarian cancer that has relapsed at least 6 months after completion of platinum-based therapy.

Gemcitabine in combination with paclitaxel is indicated for the first-line treatment of patients with metastatic breast cancer after failure of prior anthracycline-containing adjuvant chemotherapy, unless anthracyclines were clinically contraindicated.

Gemcitabine in combination with cisplatin is indicated for the first-line treatment of patients with inoperable, locally advanced (Stage IIIA or IIIB), or metastatic (Stage IV) non-small cell lung cancer (NSCLC).

Gemcitabine is indicated as first-line treatment for patients with locally advanced (nonresectable Stage II or Stage III) or metastatic (Stage IV) adenocarcinoma of the pancreas. Gemcitabine is indicated for patients previously treated with fluorouracil.

Recommended Dose and Schedule

The recommended dosage of Gemcitabine for Injection USP is 1000 mg/m² intravenously over 30 minutes on Days 1 and 8 of each 21-day cycle in combination with carboplatin AUC 4 administered intravenously on Day 1 after Gemcitabine for Injection USP administration. Refer to carboplatin prescribing information for additional information.

Dosage Modifications

Recommended Gemcitabine for Injection USP dosage modifications for myelosuppression are described in Tables 1 and 2 [see Warnings and Precautions (5.2)]. Refer to the recommended dosage modifications for non-hematologic adverse reactions [see Dosage and Administration (2.5)]. 

Recommended Dose and Schedule

The recommended dosage of Gemcitabine for Injection USP is 1250 mg/m² intravenously over 30 minutes on Days 1 and 8 of each 21-day cycle in combination with paclitaxel 175 mg/m² administered as a 3-hour intravenous infusion on Day 1 before Gemcitabine for Injection USP administration. Refer to paclitaxel prescribing information for additional information.

Dosage Modifications

Recommended Gemcitabine for Injection USP dosage modifications for myelosuppression are described in Table 3 [see Warnings and Precautions (5.2)]. Refer to the recommended dosage modifications for non-hematologic adverse reactions [see Dosage and Administration (2.5)]. 

Recommended Dose and Schedule

28-day schedule

The recommended dosage of Gemcitabine for Injection USP is 1000 mg/m² intravenously over 30 minutes on Days 1, 8, and 15 of each 28-day cycle in combination with cisplatin 100 mg/m² administered intravenously on Day 1 after Gemcitabine for Injection USP administration.

21-day schedule

The recommended dosage of Gemcitabine for Injection USP is 1250 mg/m² intravenously over 30 minutes on Days 1 and 8 of each 21-day cycle in combination with cisplatin 100 mg/m²administered intravenously on Day 1 after Gemcitabine for Injection USP administration.

Refer to cisplatin prescribing information for additional information.

Dosage Modifications

Recommended dosage modifications for Gemcitabine for Injection USP myelosuppression are described in Table 4 [see Warnings and Precautions (5.2)]. Refer to the recommended dosage modifications for non-hematologic adverse reactions [see Dosage and Administration (2.5)].

Recommended Dose and Schedule

The recommended dosage of Gemcitabine for Injection USP is 1000 mg/m² intravenously over 30 minutes. The recommended treatment schedule is as follows:

• Weeks 1 to 8: weekly dosing for the first 7 weeks followed by one week rest.
• After week 8: weekly dosing on Days 1, 8, and 15 of each 28-day cycle.

Dosage Modifications

Recommended dosage modifications for Gemcitabine for Injection USP for myelosuppression are described in Table 4 [see Warnings and Precautions (5.2)]. Refer to the recommended dosage modifications for non-hematologic adverse reactions [see Dosage and Administration (2.5)].

Permanently discontinue Gemcitabine for Injection USP for any of the following:

• Unexplained dyspnea or evidence of severe pulmonary toxicity [see Warnings and Precautions (5.3)]
• Hemolytic-uremic syndrome (HUS) or severe renal impairment [see Warnings and Precautions (5.4)]
• Severe hepatic toxicity [see Warnings and Precautions (5.5)]
• Capillary leak syndrome (CLS) [see Warnings and Precautions (5.8)]
• Posterior reversible encephalopathy syndrome (PRES) [see Warnings and Precautions (5.9)]

Withhold Gemcitabine for Injection USP or reduce dose by 50% for other Grade 3 or 4 non-hematological adverse reactions until resolved. No dose modifications are recommended for alopecia, nausea, or vomiting.

•   Gemcitabine for Injection USP vials contain no antimicrobial preservatives and are intended for single use only.
•   Gemcitabine is a cytotoxic drug. Follow applicable special handling and disposal procedures.¹
•   Exercise caution and wear gloves when preparing gemcitabine solutions. Immediately wash the skin thoroughly or rinse the mucosa with copious amounts of water if gemcitabine contacts the skin or mucus membranes. Death has occurred in animal studies due to dermal absorption.
•   Reconstitute the 200 mg vial with 5 mL and the 1 g vial with 25 mL of 0.9% Sodium Chloride Injection, USP to yield a gemcitabine concentration of 38 mg/mL. Reconstituted Gemcitabine for Injection USP is a clear, colorless to light straw-colored solution.
•   Visually inspect reconstituted product for particulate matter and discoloration. Discard if particulate matter or discoloration is observed.
•   Withdraw the calculated dose from the vial and discard any unused portion.
•   Prior to administration, dilute the reconstituted solution with 0.9% Sodium Chloride Injection, USP to a minimum final concentration of at least 0.1 mg/mL.
•   Store Gemcitabine for Injection USP solutions (reconstituted and diluted) at controlled room temperature of 20°C to 25°C (68°F to 77°F). Do not refrigerate as crystallization can occur. Discard Gemcitabine for Injection USP solutions if not used within 24 hours after reconstitution.
•   No incompatibilities have been observed with infusion bottles or polyvinyl chloride bags and administration sets.

For injection: 200 mg gemcitabine or 1 g gemcitabine as a sterile white to off-white lyophilized powder in a single-dose vial for reconstitution.

Gemcitabine for Injection USP is contraindicated in patients with a known hypersensitivity to gemcitabine. Reactions include anaphylaxis [see Adverse Reactions (6.1)].

In clinical trials evaluating the maximum tolerated dose of Gemcitabine for Injection USP, prolongation of the infusion time beyond 60 minutes or more frequent than weekly dosing resulted in an increased incidence of clinically significant hypotension, severe flu-like symptoms, myelosuppression, and asthenia. The half-life of gemcitabine is influenced by the length of the infusion [see Clinical Pharmacology (12.3)]. Refer to the recommended Gemcitabine for Injection USP dosage [see Dosage and Administration (2.1, 2.2, 2.3, 2.4)].

Myelosuppression manifested by neutropenia, thrombocytopenia, and anemia occurs with gemcitabine as a single agent and the risks are increased when gemcitabine is combined with other cytotoxic drugs. In clinical trials, Grade 3-4 neutropenia, anemia, and thrombocytopenia occurred in 25%, 8%, and 5%, respectively of the 979 patients who received single agent gemcitabine. The frequencies of Grade 3-4 neutropenia, anemia, and thrombocytopenia varied from 48% to 71%, 8% to 28%, and 5% to 55%, respectively, in patients receiving Gemcitabine for Injection USP in combination with another drug [see Adverse Reactions (6.1)].

Prior to each dose of Gemcitabine for Injection USP, obtain a complete blood count (CBC) with a differential and a platelet count. Modify the dosage as recommended [see Dosage and Administration (2.1, 2.2, 2.3, 2.4)].

Pulmonary toxicity, including interstitial pneumonitis, pulmonary fibrosis, pulmonary edema, and adult respiratory distress syndrome (ARDS), has been reported. In some cases, these pulmonary events can lead to fatal respiratory failure despite the discontinuation of therapy. The onset of pulmonary symptoms may occur up to 2 weeks after the last dose of Gemcitabine for Injection USP [see Adverse Reactions (6.1, 6.2)].

Permanently discontinue Gemcitabine for Injection USP in patients who develop unexplained dyspnea, with or without bronchospasm, or evidence of severe pulmonary toxicity.

Hemolytic uremic syndrome (HUS), including fatalities from renal failure or the requirement for dialysis, can occur with Gemcitabine for Injection USP. In clinical trials, HUS occurred in 0.25% of 2429 patients. Most fatal cases of renal failure were due to HUS [see Adverse Reactions (6.1)]. Serious cases of thrombotic microangiopathy other than HUS have been reported with Gemcitabine for Injection USP [see Adverse Reactions (6.2)].

Assess renal function prior to initiation of Gemcitabine for Injection USP and periodically during treatment. Consider the diagnosis of HUS in patients who develop anemia with evidence of microangiopathic hemolysis; increased bilirubin or LDH; reticulocytosis; severe thrombocytopenia; or renal failure (increased serum creatinine or BUN). Permanently discontinue Gemcitabine for Injection USP in patients with HUS or severe renal impairment. Renal failure may not be reversible even with the discontinuation of therapy.

Drug-induced liver injury, including liver failure and death, has been reported in patients receiving Gemcitabine for Injection USP alone or with other potentially hepatotoxic drugs [see Adverse Reactions (6.1, 6.2)]. Administration of Gemcitabine for Injection USP in patients with concurrent liver metastases or a pre-existing medical history of hepatitis, alcoholism, or liver cirrhosis can lead to exacerbation of the underlying hepatic insufficiency. Assess hepatic function prior to initiation of Gemcitabine for Injection USP and periodically during treatment. Permanently discontinue Gemcitabine for Injection USP in patients who develop severe hepatic toxicity.

Based on animal data and its mechanism of action, Gemcitabine for Injection USP can cause fetal harm when administered to a pregnant woman. Gemcitabine was teratogenic, embryotoxic, and fetotoxic in mice and rabbits.

Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with Gemcitabine for Injection USP and for 6 months after the final dose. Advise male patients with female partners of reproductive potential to use effective contraception during treatment with Gemcitabine for Injection USP and for 3 months following the final dose [see Use in Specific Populations (8.1, 8.3)].

Gemcitabine for Injection USP is not recommended for use in combination with radiation therapy.

Concurrent (given together or less than or equal to 7 days apart)

Life-threatening mucositis, especially esophagitis and pneumonitis occurred in a trial in which Gemcitabine for Injection USP was administered at a dose of 1000 mg/m² to patients with non-small cell lung cancer for up to 6 consecutive weeks concurrently with thoracic radiation.

Non-concurrent (given greater than 7 days apart)

Excessive toxicity has not been observed when Gemcitabine for Injection USP is administered more than 7 days before or after radiation. Radiation recall has been reported in patients who received Gemcitabine for Injection USP after prior radiation.

Capillary leak syndrome (CLS) with severe consequences has been reported in patients receiving Gemcitabine for Injection USP as a single agent or in combination with other chemotherapeutic agents [see Adverse Reactions (6.2)]. Permanently discontinue Gemcitabine for Injection USP if CLS develops during therapy.

Posterior reversible encephalopathy syndrome (PRES) has been reported in patients receiving Gemcitabine for Injection USP as a single agent or in combination with other chemotherapeutic agents [see Adverse Reactions (6.2)]. PRES can present with headache, seizure, lethargy, hypertension, confusion, blindness, and other visual and neurologic disturbances. Confirm the diagnosis of PRES with magnetic resonance imaging (MRI). Permanently discontinue Gemcitabine for Injection USP if PRES develops during therapy.

The following clinically significant adverse reactions are described elsewhere in the labeling:

•   Hypersensitivity[see Contraindications (4)]
•   Schedule-Dependent Toxicity [ see Warnings and Precautions (5.1)]
•   Myelosuppression [see Warnings and Precautions (5.2)]
•   Pulmonary Toxicity and Respiratory Failure [see Warnings and Precautions (5.3)]
•   Hemolytic Uremic Syndrome [see Warnings and Precautions (5.4)]
•   Hepatic Toxicity [ see Warnings and Precautions (5.5)]
•   Exacerbation of Radiation Therapy Toxicity [ see Warnings and Precautions (5.7)]
•   Capillary Leak Syndrome [see Warnings and Precautions (5.8)]
•   Posterior Reversible Encephalopathy Syndrome [see Warnings and Precautions (5.9)]

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.

Single Agent

The data described below reflect exposure to Gemcitabine for Injection USP as a single agent administered at doses between 800 mg/m² to 1250 mg/m² intravenously over 30 minutes once weekly in 979 patients with various malignancies. The most common (greater than or equal to 20%) adverse reactions of single agent Gemcitabine for Injection USP are nausea/vomiting, anemia, increased alanine aminotransferase (ALT), increased aspartate aminotransferase (AST), neutropenia, increased alkaline phosphatase, proteinuria, fever, hematuria, rash, thrombocytopenia, dyspnea, and edema. The most common (greater than or equal to 5%) Grade 3 or 4 adverse reactions were neutropenia, nausea/vomiting, increased ALT, increased alkaline phosphatase, anemia, increased AST, and thrombocytopenia. Approximately 10% of the 979 patients discontinued Gemcitabine for Injection USP due to adverse reactions. Adverse reactions resulting in discontinuation of Gemcitabine for Injection USP in 2% of 979 patients were cardiovascular adverse reactions (myocardial infarction, cerebrovascular accident, arrhythmia, and hypertension) and adverse reactions resulting in discontinuation of Gemcitabine for Injection USP in less than 1% of 979 patients were anemia, thrombocytopenia, hepatic dysfunction, renal dysfunction, nausea/vomiting, fever, rash, dyspnea, hemorrhage, infection, stomatitis, somnolence, flu-like syndrome, and edema.

Tables 5 and 6 present the incidence of selected adverse reactions and laboratory abnormalities reported in patients with various malignancies receiving single agent Gemcitabine for Injection USP across 5 clinical trials. Additional clinically significant adverse reactions are provided following Table 6.

Additional adverse reactions include the following:

• Transfusion requirements: Red blood cell transfusions (19%); platelet transfusions (less than 1%)
• Edema: Edema (13%), peripheral edema (20%), generalized edema (less than 1%)
• Flu-like symptoms: Fever, asthenia, anorexia, headache, cough, chills, myalgia, asthenia insomnia, rhinitis, sweating, and/or malaise (19%)
• Infection: Sepsis (less than 1%)
• Extravasation: Injection-site reactions (4%)
• Allergic: Bronchospasm (less than 2%); anaphylactoid reactions

Ovarian Cancer

Tables 7 and 8 present the incidence of selected adverse reactions and laboratory abnormalities, occurring in greater than or equal to 10% of gemcitabine-treated patients and at a higher incidence in the gemcitabine with carboplatin arm, reported in a randomized trial (Study 1) of gemcitabine with carboplatin (n=175) compared to carboplatin alone (n=174) for the second-line treatment of ovarian cancer in women with disease that had relapsed more than 6 months following first-line platinum-based chemotherapy [see Clinical Studies (14.1)]. Additional clinically significant adverse reactions, occurring in less than 10% of patients, are provided following Table 8.

The proportion of patients with dose adjustments for carboplatin (1.8% versus 3.8%), doses of carboplatin omitted (0.2% versus 0) and discontinuing treatment for adverse reactions (11% versus 10%), were similar between arms. Dose adjustment for gemcitabine occurred in 10% of patients and gemcitabine dose was omitted in 14% of patients in the gemcitabine/carboplatin arm.

Hematopoietic growth factors were administered more frequently in the gemcitabine-containing arm: leukocyte growth factor (24% and 10%) and erythropoiesis-stimulating agent (7% and 3.9%).

The following clinically relevant Grade 3 and 4 adverse reactions occurred more frequently in the gemcitabine with carboplatin arm: dyspnea (3.4% versus 2.9%), febrile neutropenia (1.1% versus 0), hemorrhagic event (2.3% versus 1.1 %), motor neuropathy (1.1% versus 0.6%), and rash/desquamation (0.6% versus 0).

Breast Cancer

Tables 9 and 10 present the incidence of selected adverse reactions and laboratory abnormalities, occurring in greater than or equal to 10% of gemcitabine-treated patients and at a higher incidence in the gemcitabine with paclitaxel arm, reported in a randomized trial (Study 2) of gemcitabine with paclitaxel (n=262) compared to paclitaxel alone (n=259) for the first-line treatment of metastatic breast cancer (MBC) in women who received anthracycline-containing chemotherapy in the adjuvant/neoadjuvant setting or for whom anthracyclines were contraindicated [see Clinical Studies (14.2)]. Additional clinically significant adverse reactions, occurring in less than 10% of patients, are provided following Table 10.

The requirement for dose reduction of paclitaxel were higher for patients in the gemcitabine/paclitaxel arm (5% versus 2%). The number of paclitaxel doses omitted (less than 1%), the proportion of patients discontinuing treatment for adverse reactions (7% versus 5%) and the number of treatment-related deaths (1 patient in each arm) were similar between the two arms.

Clinically relevant Grade 3 or 4 dyspnea occurred with a higher incidence in the gemcitabine with paclitaxel arm compared with the paclitaxel arm (1.9% versus 0).

Non-Small Cell Lung Cancer

Tables 11 and 12 present the incidence of selected adverse reactions and laboratory abnormalities occurring in greater than or equal to 10% of gemcitabine-treated patients and at a higher incidence in the gemcitabine with cisplatin arm, reported in a randomized trial (Study 3) of gemcitabine with cisplatin (n=260) administered in 28-day cycles as compared to cisplatin alone (n=262) in patients receiving first-line treatment for locally advanced or metastatic NSCLC [see Clinical Studies (14.3)].

Patients randomized to gemcitabine with cisplatin received a median of 4 cycles of treatment and those randomized to cisplatin alone received a median of 2 cycles of treatment. In this trial, the requirement for dose adjustments (greater than 90% versus 16%), discontinuation of treatment for adverse reactions (15% versus 8%), and the proportion of patients hospitalized (36% versus 23%) were all higher for patients receiving gemcitabine with cisplatin compared to those receiving cisplatin alone. The incidence of febrile neutropenia (3% versus less than 1%), sepsis (4% versus 1%), Grade 3 cardiac dysrhythmias (3% versus less than 1%) were all higher in the gemcitabine with cisplatin arm compared to the cisplatin alone arm. The two-drug combination was more myelosuppressive with 4 (1.5%) possibly treatment- related deaths, including 3 resulting from myelosuppression with infection and one case of renal failure associated with pancytopenia and infection. No deaths due to treatment were reported on the cisplatin arm.

Tables 13 and 14 present the incidence of selected adverse reactions and laboratory abnormalities occurring in greater than or equal to 10% of gemcitabine-treated patients and at a higher incidence in the gemcitabine with cisplatin arm, reported in a randomized trial (Study 4) of gemcitabine with cisplatin (n=69) administered in 21-day cycles as compared to etoposide with cisplatin (n=66) in patients receiving first-line treatment for locally advanced or metastatic NSCLC [see Clinical Studies (14.3)]. Additional clinically significant adverse reactions are provided following Table 14.

Patients in the gemcitabine/cisplatin (GC) arm received a median of 5 cycles and those in the etoposide/cisplatin (EC) arm received a median of 4 cycles. The majority of patients receiving more than one cycle of treatment required dose adjustments; 81% in the GC arm and 68% in the EC arm. The incidence of hospitalizations for adverse reactions was 22% in the GC arm and 27% in the EC arm. The proportion of patients who discontinued treatment for adverse reactions was higher in the GC arm (14% versus 8%). The proportion of patients who were hospitalized for febrile neutropenia was lower in the GC arm (7% versus 12%). There was one death attributed to treatment, a patient with febrile neutropenia and renal failure, which occurred in the GC arm.

The following adverse reactions have been identified during postapproval use of Gemcitabine for Injection USP. 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.

•   Blood and lymphatic system: Thrombotic microangiopathy (TMA)
•   Cardiovascular : Congestive heart failure, myocardial infarction, arrhythmias, supraventricular arrhythmias
•   Vascular: Peripheral vasculitis, gangrene, capillary leak syndrome
•   Skin: Cellulitis, pseudocellulitis, severe skin reactions, including desquamation and bullous skin eruptions
•   Hepatic: Hepatic failure, hepatic veno-occlusive disease
•   Pulmonary: Interstitial pneumonitis, pulmonary fibrosis, pulmonary edema, adult respiratory distress syndrome (ARDS), pulmonary eosinophilia
•   Nervous System : Posterior reversible encephalopathy syndrome (PRES)

Risk Summary

Based on animal data and its mechanism of action, gemcitabine can cause fetal harm when administered to a pregnant woman [see Clinical Pharmacology (12.1)]. There are no available data on the use of gemcitabine in pregnant women. In animal reproduction studies, gemcitabine was teratogenic, embryotoxic, and fetotoxic in mice and rabbits (see Data). Advise pregnant women of the potential risk to a fetus [see Use in Special Populations (8.3)].

In the U.S. general population, the estimated background risk of major birth defects and miscarriages in clinically recognized pregnancies is 2-4% and 15-20% respectively.

Data

Animal Data

Gemcitabine is embryotoxic in mice. Daily dosing of gemcitabine to pregnant mice increased the incidence of fetal malformation (cleft palate, incomplete ossification) at doses of 1.5 mg/kg/day [approximately 0.005 times the 1000 mg/m² clinical dose based on body surface area (BSA)]. Gemcitabine was embryotoxic and fetotoxic in rabbits. Daily dosing of gemcitabine to pregnant rabbits resulted in fetotoxicity (decreased fetal viability, reduced litter sizes, and developmental delays) and increased the incidence of fetal malformations (fused pulmonary artery, absence of gall bladder) at doses of 0.1 mg/kg/day (approximately 0.002 times the 1000 mg/m² clinical dose based on BSA).

Risk Summary

There is no information regarding the presence of gemcitabine or its metabolites in human milk, or their effects on the breastfed infant or on milk production. Due to the potential for serious adverse reactions in breastfed infants from gemcitabine, advise women not to breastfeed during treatment with gemcitabine and for at least one week following the last dose.

Pregnancy Testing

Verify pregnancy status in females of reproductive potential prior to initiating gemcitabine [see Use in Specific Populations (8.1)].

Contraception

Gemcitabine can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)].

Females

Because of the potential for genotoxicity, advise females of reproductive potential to use effective contraception during treatment with gemcitabine and for 6 months after the final dose of gemcitabine.

Males

Because of the potential for genotoxicity, advise males with female partners of reproductive potential to use effective contraception during treatment with gemcitabine and for 3 months after the final dose [see Nonclinical Toxicology (13.1)].

Infertility

Males

Based on animal studies, gemcitabine may impair fertility in males of reproductive potential [see Nonclinical Toxicology (13.1)]. It is not known whether these effects on fertility are reversible.

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

The safety and pharmacokinetics of gemcitabine were evaluated in a trial in pediatric patients with refractory leukemia. The maximum tolerated dose was 10 mg/m²/min for 360 minutes weekly for three weeks followed by a one-week rest period.

The safety and activity of gemcitabine were evaluated in a trial of pediatric patients with relapsed acute lymphoblastic leukemia (22 patients) and acute myelogenous leukemia (10 patients) at a dose of 10 mg/m²/min administered over 360 minutes weekly for three weeks followed by a one-week rest period. Patients with M1 or M2 bone marrow on Day 28 who did not experience unacceptable toxicity were eligible to receive a maximum of one additional four-week course. Toxicities observed included myelosuppression, febrile neutropenia, increased serum transaminases, nausea, and rash/desquamation. No meaningful clinical activity was observed in this trial.

In clinical studies which enrolled 979 patients with various malignancies who received single agent gemcitabine, no overall differences in safety were observed between patients aged 65 and older and younger patients, with the exception of a higher rate of Grade 3-4 thrombocytopenia in older patients as compared to younger patients.

In a randomized trial in women with ovarian cancer (Study 1), 175 women received gemcitabine with carboplatin, of which 29% were age 65 years or older. Similar effectiveness was observed between older and younger women. There was significantly higher Grade 3-4 neutropenia in women 65 years of age or older [see Dosage and Administration (2.1)].

Gemcitabine clearance is affected by age; however, there are no recommended dose adjustments based on patients' age [see Clinical Pharmacology (12.3)].

Gemcitabine clearance is decreased in females [see Clinical Pharmacology (12.3)]. In single agent studies of gemcitabine, women, especially older women, were more likely not to proceed to a subsequent cycle and to experience Grade 3-4 neutropenia and thrombocytopenia [see Dosage and Administration (2.1, 2.2, 2.3, 2.4)].

Gemcitabine kills cells undergoing DNA synthesis and blocks the progression of cells through the G1/S-phase boundary. Gemcitabine is metabolized by nucleoside kinases to diphosphate (dFdCDP) and triphosphate (dFdCTP) nucleosides. Gemcitabine diphosphate inhibits ribonucleotide reductase, an enzyme responsible for catalyzing the reactions that generate deoxynucleoside triphosphates for DNA synthesis, resulting in reductions in deoxynucleotide concentrations, including dCTP. Gemcitabine triphosphate competes with dCTP for incorporation into DNA. The reduction in the intracellular concentration of dCTP by the action of the diphosphate enhances the incorporation of gemcitabine triphosphate into DNA (self-potentiation). After the gemcitabine nucleotide is incorporated into DNA, only one additional nucleotide is added to the growing DNA strands, which eventually results in the initiation of apoptotic cell death.

The pharmacokinetics of gemcitabine were examined in 353 patients with various solid tumors. Pharmacokinetic parameters were derived using data from patients treated for varying durations of therapy given weekly with periodic rest weeks and using both short infusions (less than 70 minutes) and long infusions (70 to 285 minutes). The total gemcitabine dose varied from 500 mg/m² to 3600 mg/m².

Distribution

The volume of distribution was increased with infusion length. Volume of distribution of gemcitabine was 50 L/m² following infusions lasting less than 70 minutes. For long infusions, the volume of distribution rose to 370 L/m².

Gemcitabine pharmacokinetics are linear and are described by a 2-compartment model. Population pharmacokinetic analyses of combined single and multiple dose studies showed that the volume of distribution of gemcitabine was significantly influenced by duration of infusion and sex. Gemcitabine plasma protein binding is negligible.

Elimination

Metabolism

The active metabolite, gemcitabine triphosphate, can be extracted from peripheral blood mononuclear cells. The half-life of the terminal phase for gemcitabine triphosphate from mononuclear cells ranges from 1.7 to 19.4 hours.

Excretion

Gemcitabine disposition was studied in 5 patients who received a single 1000 mg/m² of radiolabeled drug as a 30-minute infusion. Within one week, 92% to 98% of the dose was recovered, almost entirely in the urine. Gemcitabine (less than 10%) and the inactive uracil metabolite, 2´-deoxy-2´,2´-difluorouridine (dFdU) accounted for 99% of the excreted dose. The metabolite dFdU is also found in plasma.

Specific Populations

Geriatric Patients

Clearance of gemcitabine was affected by age. The lower clearance in geriatric patients results in higher concentrations of gemcitabine for any given dose. Differences in either clearance or volume of distribution based on patient characteristics or the duration of infusion result in changes in half-life and plasma concentrations. Table 15 shows plasma clearance and half-life of gemcitabine following short infusions for typical patients by age and sex.

Gemcitabine half-life for short infusions ranged from 42 to 94 minutes and for long infusions varied from 245 to 638 minutes, depending on age and sex, reflecting a greatly increased volume of distribution with longer infusions.

Male and Female Patients

Females have lower clearance and longer half-lives than male patients as described in Table 15.

Patients with Renal Impairment

No clinical studies have been conducted with gemcitabine in patients with decreased renal function.

Patients with Hepatic Impairment

No clinical studies have been conducted with gemcitabine in patients with decreased hepatic function.

Drug Interactions Studies

When gemcitabine (1250 mg/m² on Days 1 and 8) and cisplatin (75 mg/m² on Day 1) were administered in patients with NSCLC, the clearance of gemcitabine on Day 1 was 128 L/hr/m² and on Day 8 was 107 L/hr/m². Data from patients with NSCLC demonstrate that gemcitabine and carboplatin given in combination does not alter the pharmacokinetics of gemcitabine or carboplatin compared to administration of either single agent; however, due to wide confidence intervals and small sample size, interpatient variability may be observed.

Data from metastatic breast cancer patients shows that gemcitabine has little or no effect on the pharmacokinetics (clearance and half-life) of paclitaxel and paclitaxel has little or no effect on the pharmacokinetics of gemcitabine.

Long-term animal studies to evaluate the carcinogenic potential of gemcitabine have not been conducted. Gemcitabine was mutagenic in an in vitro mouse lymphoma (L5178Y) assay and was clastogenic in an in vivo mouse micronucleus assay. Gemcitabine intraperitoneal doses of 0.5 mg/kg/day [about 1/700 the 1000 mg/m² clinical dose based on body surface area (BSA)] in male mice resulted in moderate to severe hypospermatogenesis, decreased fertility, and decreased implantations. In female mice, fertility was not affected but maternal toxicities were observed at 1.5 mg/kg/day administered intravenously (about 1/200 the 1000 mg/m² clinical dose based on BSA) and fetotoxicity or embryolethality was observed at 0.25 mg/kg/day administered intravenously (about 1/1300 the 1000 mg/m² clinical dose based on BSA).

The efficacy of gemcitabine was evaluated in a randomized trial (Study 1) conducted in women with advanced ovarian cancer that had relapsed at least 6 months after first-line platinum-based therapy. Patients were randomized to receive either gemcitabine 1000 mg/m² on Days 1 and 8 of each 21-day cycle with carboplatin AUC 4 on Day 1 after gemcitabine administration (n=178) or carboplatin AUC 5 on Day 1 of each 21-day cycle (n=178). The major efficacy outcome measure was progression free survival (PFS).

A total of 356 patients were enrolled. Demographics and baseline characteristics are shown in Table 16.

Efficacy results are presented in Table 17 and Figure 1. The addition of gemcitabine to carboplatin resulted in statistically significant improvements in PFS and overall response rate. Approximately 75% of patients in each arm received additional chemotherapy for disease progression; 13 of 120 patients in the carboplatin alone arm received gemcitabine for treatment of disease progression. There was no significant difference in overall survival between the treatment arms.

Figure 1: Kaplan-Meier Curves for Progression Free Survival in Study 1

The efficacy of gemcitabine was evaluated in a multinational, randomized, open-label trial (Study 2) conducted in women receiving initial treatment for metastatic breast cancer and who have received prior adjuvant/neoadjuvant anthracycline chemotherapy unless clinically contraindicated. Patients were randomized to receive either gemcitabine 1250 mg/m² on Days 1 and 8 of each 21-day cycle with paclitaxel 175 mg/m² administered on Day 1 before gemcitabine administration (n=267) or paclitaxel 175 mg/m² on Day 1 of each 21-day cycle (n=262). The major efficacy outcome measure was time to documented disease progression.

A total of 529 patients were enrolled. Demographic and baseline characteristics were similar between treatment arms (Table 18).

Efficacy results are presented in Table 19 and Figure 2. The addition of gemcitabine to paclitaxel resulted in statistically significant improvement in time to documented disease progression and overall response rate compared to paclitaxel alone. There was no significant difference in overall survival.

Figure 2: Kaplan-Meier Curves for Time to Documented Disease Progression in Study 2

The efficacy of gemcitabine was evaluated in two randomized, multicenter trials.

Study 3: 28-Day Schedule

A multinational, randomized trial (Study 3) compared gemcitabine with cisplatin to cisplatin alone in the treatment of patients with inoperable Stage IIIA, IIIB, or IV NSCLC who had not received prior chemotherapy. Patients were randomized to receive either gemcitabine 1000 mg/m² on Days 1, 8, and 15 of each 28-day cycle with cisplatin 100 mg/m² on Day 1 after gemcitabine administration (N=260) or cisplatin 100 mg/m² on Day 1 of each 28-day cycle (N=262). The major efficacy outcome measure was overall survival.

A total of 522 patients were enrolled. Demographics and baseline characteristics (Table 20) were similar between arms with the exception of histologic subtype of NSCLC, with 48% of patients on the cisplatin arm and 37% of patients on the gemcitabine with cisplatin arm having adenocarcinoma.

Efficacy results are presented in Table 21 and Figure 3.

Study 4: 21-Day Schedule

A randomized (1:1), multicenter trial (Study 4) was conducted in patients with Stage IIIB or IV NSCLC. Patients were randomized to receive either gemcitabine 1250 mg/m² on Days 1 and 8 of each 21-day cycle with cisplatin 100 mg/m² on Day 1 after gemcitabine administration or etoposide 100 mg/m² intravenously on Days 1, 2, and 3 with cisplatin 100 mg/m² on Day 1 of each 21-day cycle. The major efficacy outcome measure was response rate.

A total of 135 patients were enrolled. Demographics and baseline characteristics are summarized in Table 20.

Efficacy results are presented in Table 21. There was no significant difference in survival between the two treatment arms. The median survival was 8.7 months for the gemcitabine with cisplatin arm versus 7 months for the etoposide with cisplatin arm. Median time to disease progression for the gemcitabine with cisplatin arm was 5 months compared to 4.1 months on the etoposide with cisplatin arm (Log rank p=0.015, two-sided). The objective response rate for the gemcitabine with cisplatin arm was 33% compared to 14% on the etoposide with cisplatin arm (Fisher's Exact p=0.01, two-sided).

Figure 3: Kaplan-Meier Curves for Overall Survival in Study 3

The efficacy of gemcitabine was evaluated in two trials (Studies 5 and 6), a randomized, single-blind, two-arm, active-controlled trial (Study 5) conducted in patients with locally advanced or metastatic pancreatic cancer who had received no prior chemotherapy and in a single-arm, open-label, multicenter trial (Study 6) conducted in patients with locally advanced or metastatic pancreatic cancer previously treated with fluorouracil or a fluorouracil-containing regimen. In Study 5, patients were randomized to receive either gemcitabine 1000 mg/m² intravenously over 30 minutes once weekly for 7 weeks followed by a one-week rest, then once weekly for 3 consecutive weeks every 28-days in subsequent cycles (n=63) or fluorouracil 600 mg/m² intravenously over 30 minutes once weekly (n=63). In Study 6, all patients received gemcitabine 1000 mg/m² intravenously over 30 minutes once weekly for 7 weeks followed by a one-week rest, then once weekly for 3 consecutive weeks every 28-days in subsequent cycles.

The major efficacy outcome measure in both trials was "clinical benefit response". A patient was considered to have had a clinical benefit response if either of the following occurred:

• The patient achieved a greater than or equal to 50% reduction in pain intensity (Memorial Pain Assessment Card) or analgesic consumption, or a 20-point or greater improvement in performance status (Karnofsky Performance Status) for a period of at least 4 consecutive weeks, without showing any sustained worsening in any of the other parameters. Sustained worsening was defined as 4 consecutive weeks with either any increase in pain intensity or analgesic consumption or a 20-point decrease in performance status occurring during the first 12 weeks of therapy.

OR

• The patient was stable on all of the aforementioned parameters, and showed a marked, sustained weight gain (greater than or equal to 7% increase maintained for greater than or equal to 4 weeks) not due to fluid accumulation.

Study 5 enrolled 126 patients. Demographics and baseline characteristics were similar between the arms (Table 22).

The efficacy results are shown in Table 23 and Figure 4. Patients treated with gemcitabine had statistically significant increases in clinical benefit response, survival, and time to disease progression compared to those randomized to receive fluorouracil. No confirmed objective tumor responses were observed in either treatment arm.

Figure 4: Kaplan-Meier Curves for Overall Survival in Study 5