Gemzar Description

Gemzar® (gemcitabine HCl) is a nucleoside analogue that exhibits antitumor activity. Gemcitabine HCl is 2?-deoxy-2?,2?-difluorocytidine monohydrochloride (??isomer).

The structural formula is as follows:

The empirical formula for gemcitabine HCl is C9 H11 F2 N3 O4  ? HCl. It has a molecular weight of 299.66.

Gemcitabine HCl is a white to off?white solid. It is soluble in water, slightly soluble in methanol, and practically insoluble in ethanol and polar organic solvents.

The clinical formulation is supplied in a sterile form for intravenous use only. Vials of Gemzar contain either 200 mg or 1 g of gemcitabine HCl (expressed as free base) formulated with mannitol (200 mg or 1 g, respectively) and sodium acetate (12.5 mg or 62.5 mg, respectively) as a sterile lyophilized powder. Hydrochloric acid and/or sodium hydroxide may have been added for pH adjustment.

Gemzar Indications And Usage

Therapeutic Indications

Ovarian Cancer

Gemzar 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.

Breast Cancer

Gemzar 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.

Non?small Cell Lung Cancer

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

Pancreatic Cancer

Gemzar 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. Gemzar is indicated for patients previously treated with 5?FU.

Gemzar Side Effects

Caution ? Prolongation of the infusion time beyond 60 minutes and more frequent than weekly dosing have been shown to increase toxicity ( see CLINICAL STUDIES ).

Hematology ? Gemzar can suppress bone marrow function as manifested by leukopenia, thrombocytopenia, and anemia ( see ADVERSE REACTIONS ), and myelosuppression is usually the dose?limiting toxicity. Patients should be monitored for myelosuppression during therapy. See DOSAGE AND ADMINISTRATION for recommended dose adjustments.

Pulmonary ? Pulmonary toxicity has been reported with the use of Gemzar. In cases of severe lung toxicity, Gemzar therapy should be discontinued immediately and appropriate supportive care measures instituted ( see Pulmonary under Single?Agent Use and under Post?marketing experience in ADVERSE REACTIONS section).

Renal ? Hemolytic Uremic Syndrome (HUS) and/or renal failure have been reported following one or more doses of Gemzar. Renal failure leading to death or requiring dialysis, despite discontinuation of therapy, has been rarely reported. The majority of the cases of renal failure leading to death were due to HUS ( see Renal under Single?Agent Use and under Post?marketing experience in ADVERSE REACTIONS section).

Hepatic ? Serious hepatotoxicity, including liver failure and death, has been reported very rarely in patients receiving Gemzar alone or in combination with other potentially hepatotoxic drugs ( see Hepatic under Single?Agent Use and under Post?marketing experience in ADVERSE REACTIONS section).

Pregnancy ? Pregnancy Category D. Gemzar can cause fetal harm when administered to a pregnant woman. Gemcitabine is embryotoxic causing fetal malformations (cleft palate, incomplete ossification) at doses of 1.5 mg/kg/day in mice (about 1/200 the recommended human dose on a mg/m2 basis). Gemcitabine is fetotoxic causing fetal malformations (fused pulmonary artery, absence of gall bladder) at doses of 0.1 mg/kg/day in rabbits (about 1/600 the recommended human dose on a mg/m2 basis). Embryotoxicity was characterized by decreased fetal viability, reduced live litter sizes, and developmental delays. There are no studies of Gemzar in pregnant women. If Gemzar is used during pregnancy, or if the patient becomes pregnant while taking Gemzar, the patient should be apprised of the potential hazard to the fetus.

Gemzar Precautions

General

Patients receiving therapy with Gemzar should be monitored closely by a physician experienced in the use of cancer chemotherapeutic agents. Most adverse events are reversible and do not need to result in discontinuation, although doses may need to be withheld or reduced. There was a greater tendency in women, especially older women, not to proceed to the next cycle.

Laboratory Tests

Patients receiving Gemzar should be monitored prior to each dose with a complete blood count (CBC), including differential and platelet count. Suspension or modification of therapy should be considered when marrow suppression is detected ( see DOSAGE AND ADMINISTRATION ).

Laboratory evaluation of renal and hepatic function should be performed prior to initiation of therapy and periodically thereafter ( see WARNINGS ).

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Long?term animal studies to evaluate the carcinogenic potential of Gemzar have not been conducted. Gemcitabine induced forward mutations in vitro in a mouse lymphoma (L5178Y) assay and was clastogenic in an in vivo mouse micronucleus assay. Gemcitabine was negative when tested using the Ames, in vivo sister chromatid exchange, and in vitro chromosomal aberration assays, and did not cause unscheduled DNA synthesis in vitro . Gemcitabine I.P. doses of 0.5 mg/kg/day (about 1/700 the human dose on a mg/m2 basis)in male mice had an effect on fertility with 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 I.V. (about 1/200 the human dose on a mg/m2 basis) and fetotoxicity or embryolethality was observed at 0.25 mg/kg/day I.V. (about 1/1300 the human dose on a mg/m2 basis).

Pregnancy

Category D. See WARNINGS .

Nursing Mothers

It is not known whether Gemzar or its metabolites are excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions from Gemzar in nursing infants, the mother should be warned and a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother and the potential risk to the infant.

Elderly Patients

Gemzar clearance is affected by age ( see CLINICAL PHARMACOLOGY ). There is no evidence, however, that unusual dose adjustments (i.e., other than those already recommended in the DOSAGE AND ADMINISTRATION section) are necessary in patients over 65, and in general, adverse reaction rates in the single?agent safety database of 979 patients were similar in patients above and below 65. Grade 3/4 thrombocytopenia was more common in the elderly. In the randomized clinical trial of Gemzar in combination with carboplatin for recurrent ovarian cancer ( see CLINICAL STUDIES ), 125 women treated with Gemzar plus carboplatin were <65 years and 50 were ?65 years. 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. Overall, there were no substantial differences in toxicity profile of Gemzar plus carboplatin based on age.

Gender

Gemzar clearance is affected by gender ( see CLINICAL PHARMACOLOGY ). In the single?agent safety database (N=979 patients), however, there is no evidence that unusual dose adjustments (i.e., other than those already recommended in the DOSAGE AND ADMINISTRATION section) are necessary in women. In general, in single?agent studies of Gemzar, adverse reaction rates were similar in men and women, but women, especially older women, were more likely not to proceed to a subsequent cycle and to experience Grade 3/4 neutropenia and thrombocytopenia.

Pediatric Patients

The effectiveness of Gemzar in pediatric patients has not been demonstrated. Gemzar was evaluated in a Phase 1 trial in pediatric patients with refractory leukemia and determined that the maximum tolerated dose was 10 mg/m2 /min for 360 minutes three times weekly followed by a one week rest period. Gemzar was also evaluated in a Phase 2 trial in patients with relapsed acute lymphoblastic leukemia (22 patients) and acute myelogenous leukemia (10 patients) using 10 mg/m2 /min for 360 minutes three times weekly followed by a one week rest period. Toxicities observed included bone marrow suppression, febrile neutropenia, elevation of serum transaminases, nausea, and rash/desquamation, which were similar to those reported in adults. No meaningful clinical activity was observed in this Phase 2 trial.

Patients With Renal Or Hepatic Impairment

Gemzar should be used with caution in patients with preexisting renal impairment or hepatic insufficiency as there is insufficient information from clinical studies to allow clear dose recommendation for these patient populations. Administration of Gemzar in patients with concurrent liver metastases or a pre?existing medical history of hepatitis, alcoholism, or liver cirrhosis may lead to exacerbation of the underlying hepatic insufficiency.

Drug Interactions

No specific drug interaction studies have been conducted. For information on the pharmacokinetics of Gemzar and cisplatin in combination, see Drug Interactions under CLINICAL PHARMACOLOGY section.

Radiation Therapy

A pattern of tissue injury typically associated with radiation toxicity has been reported in association with concurrent and non?concurrent use of Gemzar.

Non?concurrent (given >7 days apart) ? Analysis of the data does not indicate enhanced toxicity when Gemzar is administered more than 7 days before or after radiation, other than radiation recall. Data suggest that Gemzar can be started after the acute effects of radiation have resolved or at least one week after radiation.

Concurrent (given together or ?7 days apart) ? Pre?clinical and clinical studies have shown that Gemzar has radiosensitizing activity. Toxicity associated with this multimodality therapy is dependent on many different factors, including dose of Gemzar, frequency of Gemzar administration, dose of radiation, radiotherapy planning technique, the target tissue, and target volume. In a single trial, where Gemzar at a dose of 1000 mg/m2 was administered concurrently for up to 6 consecutive weeks with therapeutic thoracic radiation to patients with non?small cell lung cancer, significant toxicity in the form of severe, and potentially life?threatening mucositis, especially esophagitis and pneumonitis was observed, particularly in patients receiving large volumes of radiotherapy [median treatment volumes 4795 cm3 ]. Subsequent studies have been reported and suggest that Gemzar administered at lower doses with concurrent radiotherapy has predictable and less severe toxicity. However, the optimum regimen for safe administration of Gemzar with therapeutic doses of radiation has not yet been determined in all tumor types.

Gemzar Overdosage

There is no known antidote for overdoses of Gemzar. Myelosuppression, paresthesias, and severe rash were the principal toxicities seen when a single dose as high as 5700 mg/m2 was administered by I.V. infusion over 30 minutes every 2 weeks to several patients in a Phase 1 study. In the event of suspected overdose, the patient should be monitored with appropriate blood counts and should receive supportive therapy, as necessary.