2.1 Patient Selection

Select patients for the first-line treatment of metastatic NSCLC with gefitinib tablets based on the presence of EGFR exon 19 deletions or exon 21 L858R mutations in their tumor or plasma specimens [see Indications and Usage (1), Clinical Studies (14)]. If these mutations are not detected in a plasma specimen, test tumor tissue if feasible.

Information on FDA-approved tests for the detection of EGFR mutations in NSCLC is available at: http://www.fda.gov/CompanionDiagnostics.

2.2 Recommended Dose

The recommended dose of gefitinib tablets is 250 mg orally once daily with or without food until disease progression or unacceptable toxicity.

Do not take a missed dose within 12 hours of the next dose.

2.3 Administration to Patients Who Have Difficulty Swallowing Solids

Immerse gefitinib tablets in 4 to 8 ounces of water by dropping the tablet in water, and stir for approximately 15 minutes. Immediately drink the liquid or administer through a naso-gastric tube. Rinse the container with 4 to 8 ounces of water and immediately drink or administer through the naso-gastric tube.

2.4 Dose Modification

Dose Modifications for Adverse Drug Reactions

Withhold gefitinib tablets (for up to 14 days) for any of the following:

• Acute onset or worsening of pulmonary symptoms (dyspnea, cough, fever) [see Warnings and Precautions (5.1)]
  
• NCI CTCAE Grade 2 or higher in ALT and/or AST elevations [see Warnings and Precautions (5.2)]
  
• NCI CTCAE Grade 3 or higher diarrhea [see Warnings and Precautions (5.4)]
  
• Signs and symptoms of severe or worsening ocular disorders including keratitis [see Warnings and Precautions (5.5)]
  
• NCI CTCAE Grade 3 or higher skin reactions [see Warnings and Precautions (5.6)]

Resume treatment with gefitinib tablets when the adverse reaction fully resolves or improves to NCI CTCAE Grade 1.

Permanently discontinue gefitinib tablets for:

• Confirmed interstitial lung disease (ILD) [see Warnings and Precautions (5.1)]
  
• Severe hepatic impairment [see Warnings and Precautions (5.2)]
  
• Gastrointestinal perforation [see Warnings and Precautions (5.3)]
  
• Persistent ulcerative keratitis [see Warnings and Precautions (5.5)]

Dose Modifications for Drug Interactions

Strong CYP3A4 Inducers

Increase gefitinib tablets to 500 mg daily in the absence of severe adverse drug reaction, and resume gefitinib tablets at 250 mg seven days after discontinuation of the strong CYP3A4 inducer [see Drug Interactions (7), Clinical Pharmacology (12.3)].

5.1 Interstitial Lung Disease (ILD)

ILD or ILD-like adverse drug reactions (e.g., lung infiltration, pneumonitis, acute respiratory distress syndrome, or pulmonary fibrosis) occurred in 1.3% of the 2462 patients who received gefitinib tablets across clinical trials; of these, 0.7% were Grade 3 or higher and 3 cases were fatal.

Withhold gefitinib tablets and promptly investigate for ILD in any patient who presents with worsening of respiratory symptoms such as dyspnea, cough and fever. Permanently discontinue gefitinib tablets if ILD is confirmed [see Dosage and Administration (2.4), Adverse Reactions (6.1)].

5.2 Hepatotoxicity

In patients who received gefitinib tablets across clinical trials, 11.4% of patients had increased alanine aminotransferase (ALT), 7.9% of patients had increased aspartate aminotransferase (AST), and 2.7% of patients had increased bilirubin. Grade 3 or higher liver test abnormalities occurred in 5.1% (ALT), 3.0% (AST), and 0.7% (bilirubin) of patients. The incidence of fatal hepatotoxicity was 0.04%.

Obtain periodic liver function testing. Withhold gefitinib tablets in patients with worsening liver function and discontinue in patients with severe hepatic impairment [see Dosage and Administration (2.4), Adverse Reactions (6.1), Use in Specific Populations (8.7)].

5.3 Gastrointestinal Perforation

Gastrointestinal perforation occurred in three (0.1%) of the 2462 gefitinib tablets-treated patients across clinical trials [see Adverse Reactions (6.1)]. Permanently discontinue gefitinib tablets in patients who develop gastrointestinal perforation [see Dosage and Administration (2.4)].

5.4 Severe or Persistent Diarrhea

Grade 3 or 4 diarrhea occurred in 3% of 2462 gefitinib tablets-treated patients across clinical trials. Withhold gefitinib tablets for severe or persistent (up to 14 days) diarrhea [see Dosage and Administration (2.4), Adverse Reactions (6.1)].

5.5 Ocular Disorders including Keratitis

Ocular disorders [keratitis (0.1%), corneal erosion and aberrant eyelash growth (0.2%), conjunctivitis, blephritis and dry eye (6.7%)] occurred in the 2462 gefitinib tablets-treated patients across clinical trials. The incidence of Grade 3 ocular disorders was 0.1% [see Adverse Reactions (6.1)]. Interrupt or discontinue gefitinib tablets for severe, or worsening ocular disorders [see Dosage and Administration (2.4)].

5.6 Bullous and Exfoliative Skin Disorders

Bullous conditions including toxic epidermal necrolysis, Stevens Johnson syndrome and erythema multiforme have been reported from treatment with gefitinib tablets. Erythema multiforme and dermatitis bullous have been reported in two patients (0.08%) across NSCLC trials (Study 2, Study 3 and Study 4). Gefitinib tablets treatment should be interrupted or discontinued if the patient develops severe bullous, blistering or exfoliating conditions.

5.7 Embryo-fetal Toxicity

Based on its mechanism of action and data from animal reproduction studies gefitinib tablets can cause fetal harm when administered to a pregnant woman. In animal reproductive studies, oral administration of gefitinib from organogenesis through weaning resulted in fetotoxicity and neonatal death at doses below the recommended human dose. Advise pregnant women of the potential risk to a fetus. Advise females of reproductive potential to use effective contraception during treatment with gefitinib tablets and for at least two weeks following completion of therapy [see Use in Specific Populations (8.1, 8.3)].

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 safety of gefitinib tablets are based on the data from 2462 patients with NSCLC who received gefitinib tablets 250 mg daily monotherapy in three randomized clinical studies (Study 2, Study 3 and Study 4). Patients with a history of interstitial lung disease, drug-induced interstitial disease, radiation pneumonitis that required steroid treatment or any evidence of clinically active interstitial lung disease were excluded from these studies.

Controlled Studies:

Study 2 was a randomized, multicenter, open-label trial in which 1217 patients were randomized to receive first-line treatment for metastatic NSCLC; 607 patients received gefitinib tablets 250 mg daily and 589 patients received carboplatin/paclitaxel. The median duration of treatment with gefitinib tablets was 5.9 months. The study population characteristics were: median age 57 years, age less than 65 years (73%), female (79%), Asian (100%), NSCLC adenocarcinoma histology (100%), never smoker (94%), light ex-smoker (6%), ECOG PS 0 or 1 (90%).

Study 3 was a randomized, multicenter, double-blind, placebo-controlled trial in which 1692 patients were randomized to receive second- or third-line treatment for metastatic NSCLC; of which 1126 patients received gefitinib tablets 250 mg daily and 562 patients received placebo. The median duration of treatment with gefitinib tablets was 2.9 months. The study population characteristics were: median age 62 years, age less than 65 years (60%), female (33%), Caucasian (75%), Asian (21%), NSCLC adenocarcinoma histology (48%), never smoker (22%), ECOG PS 0 or 1 (65%), PS 2 (29%), PS 3 (5%) and two or more prior therapies (51%).

Study 4 was a randomized, multicenter, open-label trial in which 1466 patients were randomized to receive second-line treatment for metastatic NSCLC; 729 patients received gefitinib tablets 250 mg daily and 715 patients received docetaxel. The median duration of treatment with gefitinib tablets was 2.4 months. The study population characteristics were: median age 61 years, age less than 65 years (61%), female (36%), Caucasian (79%), Asian (21%), NSCLC adenocarcinoma histology (54%), never smoker (20%), ECOG PS 0 or 1 (88%) and two or more prior therapies (16%).

The pooled safety database from the three randomized trials was used to evaluate for serious and uncommon adverse drug reactions. Common adverse reactions were evaluated in Study 3. The most frequent adverse reactions in Study 3 (incidence of greater than 20% and greater than placebo) reported in gefitinib tablets-treated patients were skin reactions (47%) and diarrhea (29%). The most frequent fatal adverse reactions in gefitinib tablets-treated patients were respiratory failure (0.9%), pneumonia (0.8%), and pulmonary embolism (0.5%).

Approximately 5% of gefitinib tablets-treated patients and 2.3% of placebo-treated patients discontinued treatment due to an adverse event. The most frequent adverse reactions that led to discontinuation in patients treated with gefitinib tablets were nausea (0.5%), vomiting (0.5%) and diarrhea (0.4%).

The following adverse reactions have been reported with gefitinib tablets across NSCLC trials (Study 2, Study 3 and Study 4) and are not listed elsewhere in Section 6: nausea (18%), asthenia (17%), pyrexia (9%), alopecia (4.7%), hemorrhage (including epistaxis and hematuria) (4.3%), dry mouth (2%), dehydration (1.8%), elevations in blood creatinine (1.5%), allergic reactions including angioedema and urticaria (1.1%), palmar-plantar erythrodysesthesia syndrome (0.2%) and pancreatitis (0.1%).

6.2 Postmarketing Experience

The following adverse reactions have been identified during post-approval use of gefitinib tablets. 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.

Renal and urinary disorders: cystitis, hemorrhagic cystitis

Skin and subcutaneous tissue disorders: cutaneous vasculitis

7.1 Drugs Affecting Gefitinib Exposure

CYP3A4 Inducer

Drugs that are strong inducers of CYP3A4 increase the metabolism of gefitinib and decrease gefitinib plasma concentrations. Increase gefitinib tablets to 500 mg daily in patients receiving a strong CYP3A4 inducer (e.g., rifampicin, phenytoin, or tricyclic antidepressant) and resume gefitinib tablets at 250 mg 7 days after discontinuation of the strong inducer [see Dosage and Administration (2.4), Clinical Pharmacology (12.3)].

CYP3A4 Inhibitor

Drugs that are strong inhibitors of CYP3A4 (e.g., ketoconazole and itraconazole) decrease gefitinib metabolism and increase gefitinib plasma concentrations. Monitor adverse reactions when administering strong CYP3A4 inhibitors with gefitinib tablets.

Drugs Affecting Gastric pH

Drugs that elevate gastric pH (e.g., proton pump inhibitors, histamine H2-receptor antagonists, and antacids) may reduce plasma concentrations of gefitinib. Avoid concomitant use of gefitinib tablets with proton pump inhibitors, if possible. If treatment with a proton-pump inhibitor is required, take gefitinib tablets 12 hours after the last dose or 12 hours before the next dose of the proton-pump inhibitor. Take gefitinib tablets 6 hours after or 6 hours before an H2-receptor antagonist or an antacid [see Clinical Pharmacology (12.3)].

7.2 Hemorrhage in Patients taking Warfarin

International Normalized Ratio (INR) elevations and/or hemorrhage have been reported in some patients taking warfarin while on gefitinib tablets therapy. Patients taking warfarin should be monitored regularly for changes in prothrombin time or INR.

8.1 Pregnancy

Risk Summary

Based on its mechanism of action and animal data, gefitinib tablets can cause fetal harm when administered to a pregnant woman. In animal reproductive studies, oral administration of gefitinib from organogenesis through weaning resulted in fetotoxicity and neonatal death at doses below the recommended human dose (see Animal Data). Advise pregnant women of the potential hazard to a fetus or potential risk for loss of the pregnancy.

The background risk of major birth defects and miscarriage for the indicated population is unknown; however, the background risk in the U.S. general population of major birth defects is 2% to 4% and miscarriage is 15% to 20% of clinically recognized pregnancies.

Data

Animal Data

A single dose study in rats showed that gefitinib crosses the placenta after an oral dose of 5 mg/kg (30 mg/m2, about 0.2 times the recommended human dose on a mg/m2 basis). When pregnant rats were treated with 5 mg/kg from the beginning of organogenesis to the end of weaning there was a reduction in the number of offspring born alive. This effect was more severe at 20 mg/kg (approximate the human clinical dose on a mg/m2 basis) and was accompanied by high neonatal mortality soon after parturition. In rabbits, a dose of 20 mg/kg/day (240 mg/m2, about twice the recommended dose in humans on a mg/m2 basis) caused reduced fetal weight.

8.2 Lactation

Risk Summary

It is not known whether gefitinib is excreted in human milk. Animal studies indicate the gefitinib and its metabolites are present in rat milk at a concentration higher than those in maternal plasma. Because of the potential for serious adverse reactions in nursing infants from gefitinib, advise women to discontinue breastfeeding during treatment with gefitinib tablets.

Data

Animal Data

Levels of gefitinib and its metabolites were 11- to-19-fold higher in milk than in blood, after oral exposure of lactating rats to a dose of 5 mg/kg.

8.3 Females and Males of Reproductive Potential

Contraception

Based on its mechanism of action and animal data, gefitinib tablets can cause fetal harm when administered to a pregnant woman [see Use in Specific Populations (8.1)]. Advise females of reproductive potential to use effective contraception during treatment with gefitinib tablets and for at least two weeks following completion of therapy.

Infertility

Gefitinib tablets may result in reduced fertility in females of reproductive potential [see Nonclinical Toxicology (13.1)].

8.4 Pediatric Use

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

8.5 Geriatric Use

Of the 823 patients enrolled in two randomized, active-controlled clinical trials 374 patients (45%) were 65 years and older, and 93 patients (11%) were 75 years and older. No overall differences in safety were observed between patients 65 years and older and those younger than 65 years. There is insufficient information to assess for differences in efficacy between older and younger patients.

8.6 Renal Impairment

Less than four percent (<4%) of gefitinib and its metabolites are excreted via the kidney. No clinical studies were conducted with gefitinib tablets in patients with severe renal impairment.

8.7 Hepatic Impairment

The systemic exposure of gefitinib was compared in patients with mild, moderate, or severe hepatic impairment due to cirrhosis (according to Child-Pugh classification) and healthy subjects with normal hepatic function (N=10/group). The mean systemic exposure (AUC0-∞) was increased by 40% in patients with mild impairment, 263% in patients with moderate impairment, and 166% in patients with severe hepatic impairment. Monitor adverse reactions when gefitinib tablets are administered to patients with moderate and severe hepatic impairment.

In a study comparing 13 patients with liver metastases and moderate hepatic impairment (addition of CTC grade of baseline AST/SGOT, ALP, and bilirubin equals 3 to 5) to 14 patients with liver metastases and normal hepatic function, the systemic exposure of gefitinib was similar [see Warnings and Precautions (5.2)].

12.1 Mechanism of Action

The epidermal growth factor receptor (EGFR) is expressed on the cell surface of both normal and cancer cells and plays a role in the processes of cell growth and proliferation. Some EGFR activating mutations (exon 19 deletion or exon 21 point mutation L858R) within NSCLC cells have been identified as contributing to the promotion of tumor cell growth, blocking of apoptosis, increasing the production of angiogenic factors and facilitating the processes of metastasis.

Gefitinib reversibly inhibits the kinase activity of wild-type and certain activating mutations of EGFR, preventing autophosphorylation of tyrosine residues associated with the receptor, thereby inhibiting further downstream signaling and blocking EGFR-dependent proliferation.

Gefitinib binding affinity for EGFR exon 19 deletion or exon 21 point mutation L858R mutations is higher than its affinity for the wild-type EGFR. Gefitinib also inhibits IGF and PDGF-mediated signaling at clinically relevant concentrations; inhibition of other tyrosine kinase receptors has not been fully characterized.

12.3 Pharmacokinetics

Absorption and Distribution

The mean oral bioavailability of gefitinib is 60%, with peak plasma levels occurring 3 to 7 hours after dosing. Food does not alter gefitinib bioavailability to a clinically meaningful extent. Gefitinib tablets can be administered with or without food. Gefitinib is extensively distributed throughout the body with a mean steady state volume of distribution of 1400 L following intravenous administration. In vitro binding of gefitinib to human plasma proteins (serum albumin and α1-acid glycoprotein) is 90%, independent of drug concentrations. Gefitinib is a substrate for the membrane transport P-glycoprotein (P-gp), but it is unlikely to influence gefitinib absorption as P-gp is saturated at higher concentrations.

Metabolism and Elimination

Gefitinib undergoes extensive hepatic metabolism in humans, predominantly by CYP3A4. Three sites of biotransformation have been identified: metabolism of the N-propoxymorpholino-group, demethylation of the methoxysubstituent on the quinazoline, and oxidative defluorination of the halogenated phenyl group. Five metabolites have been fully identified in fecal extracts and the major active component was O-desmethyl gefitinib produced by CYP2D6 metabolism and accounted for 14% of the dose.

Eight metabolites were identified in human plasma. Only O-desmethyl gefitinib has exposure comparable to gefitinib. Although this metabolite has similar EGFR-TK activity to gefitinib in the isolated enzyme assay, it had only 1/14 of the potency of gefitinib in one of the cell-based assays.

Gefitinib is cleared primarily by the liver, with total plasma clearance and elimination half-life of 48 hours after intravenous administration. The inter-subject variability (coefficient of variation) for AUC in healthy subjects was 67%. Daily oral administration of gefitinib to cancer patients resulted in a two-fold accumulation compared to single dose administration. Steady state plasma concentrations are achieved within 10 days after daily dosing. Excretion of gefitinib and its metabolites is predominantly via the feces (86%), with renal elimination accounting for less than 4% of the administered dose.

Specific Populations

Age, gender, body weight, ethnicity or renal function: Population pharmacokinetic analyses suggest that patient age, body weight, ethnicity (populations included) or creatinine clearance (above 20 mL/min) has no clinically meaningful effect on predicted steady state trough concentration of gefitinib. Population pharmacokinetic analyses of Study 1 showed that women had 27% higher exposure than men; however, this difference was not identified in the analyses of other gefitinib clinical studies. No dose adjustment based on patient gender is recommended.

Hepatic Impairment: The systemic exposure of gefitinib was compared between patients with mild, moderate, or severe hepatic impairment due to cirrhosis (according to Child-Pugh classification) and healthy subjects with normal hepatic function (N=10/group). The mean systemic exposure (AUC0-∞) was increased by 40% in patients with mild impairment, 263% in patients with moderate impairment, and 166% in patients with severe hepatic impairment. In a study comparing 13 patients with liver metastases and moderate hepatic impairment to 14 patients with liver metastases and normal hepatic function, the systemic exposure of gefitinib was similar [see Warnings and Precautions (5.2), Use in Specific Populations (8.7)].

CYP2D6 Poor metabolizer: CYP2D6 metabolizes gefitinib to O-desmethyl gefitinib in vitro. In healthy CYP2D6 poor metabolizers, O-desmethyl gefitinib concentration was not measurable and the mean exposure to gefitinib was 2-fold higher as compared to the extensive metabolizers. This increase in exposure in CYP2D6 poor metabolizers may be clinically important because some adverse drug reactions are related to higher exposure of gefitinib. No dose adjustment is recommended in patients with a known CYP2D6 poor metabolizer genotype, but these patients should be closely monitored for adverse reactions. The impact of CYP2D6 inhibiting drugs on gefitinib pharmacokinetics has not been evaluated. However, similar precautions should be used when administering CYP2D6 inhibitors with gefitinib tablets because of the possibility of increased exposure in these patients.

An exploratory exposure response analysis showed an increase in the incidence of interstitial lung disease (ILD) with a greater than 2-fold increase in the gefitinib exposure [see Warnings and Precautions (5.1)].

Drug-Drug Interactions

Strong CYP3A4 Inducer:

Concomitant administration of rifampicin (600 mg QD for 16 days), a strong inducer of CYP3A4, with gefitinib (500 mg single dose on Day 10 of gefitinib administration) reduced mean AUC of gefitinib by 83% [see Dosage and Administration (2.4), Drug Interactions (7)].

CYP3A4 Inhibitor:

Concomitant administration of itraconazole (200 mg QD for 12 days), an inhibitor of CYP3A4, with gefitinib (250 mg single dose on Day 4 of itraconazole administration) to healthy male subjects, increased mean gefitinib AUC by 80% [see Drug Interactions (7)].

Drugs Affecting Gastric pH:

Coadministration of high doses of ranitidine with sodium bicarbonate (to maintain the gastric pH above pH 5.0) to healthy subjects decreased mean gefitinib AUC by 47% [see Drug Interactions (7)].

In human liver microsome studies, gefitinib had no inhibitory effect on CYP1A2, CYP2C9, and CYP3A4 activities at concentrations ranging from 2 to 5000 ng/mL. At the highest concentration studied (5000 ng/mL), gefitinib inhibited CYP2C19 by 24% and CYP2D6 by 43%.

Exposure to metoprolol, a substrate of CYP2D6, was increased by 30% when it was given on Day 15 of gefitinib dosing (500 mg daily for 28 days) in patients with solid tumors.

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Gefitinib has been tested for genotoxicity in a series of in vitro (bacterial mutation, mouse lymphoma, and human lymphocyte) assays and an in vivo rat micronucleus test. Under the conditions of these assays, gefitinib did not cause genetic damage.

In a two-year carcinogenicity study in mice, administration of gefitinib at a dose of 270 mg/m2/day (approximately twice the recommended daily dose of 250 mg on a mg/m2 basis; dose reduced from 375 mg/m2/day from week 22) caused hepatocellular adenomas in females. In a two-year carcinogenicity study in rats, administration of gefitinib at 60 mg/m2/day (approximately 0.4 times the recommended daily clinical dose on a mg/m2 basis) caused hepatocellular adenomas and hemangiomas/hemangiosarcomas of the mesenteric lymph nodes in female rats. The clinical relevance of these findings is unknown.

In a dedicated fertility study in rats at doses greater than or equal to 120 mg/m2 (approximately equal to the recommended human dose of gefitinib on a mg/m2 basis), animals presented with an increased incidence of irregular estrous, decreased corpora lutea, and decreases in uterine implants and live embryos per litter.