Erlotinib (Tarceva)

Erlotinib, also known as Tarceva, is a targeted cancer drug used to treat metastatic non-small cell lung cancer (NSCLC) in patients with a specific gene mutation (EGFR exon 19 deletion or exon 21 [L858R] substitution mutations) as first-line therapy, maintenance treatment, or for progressive disease.  It is also used to treat patients with locally advanced, unresectable, or metastatic pancreatic cancer. Lastly, it can be used for advanced papillary kidney cancer (off-label use).  

Mechanism of Action

Erlotinib is a tyrosine kinase inhibitor (TKI), a type of cancer growth blocker. Its mechanism of action is to block proteins on cancer cells that encourage them to grow. These proteins are called epidermal growth factor receptors (EGFR). It has been shown to be effective in patients whose cancer cells express the EGFR mutations, even though it can also be utilized in patients whose tumor cells do not express these mutations [1].

Is Erlotinib Chemotherapy?

According to Mayo Clinic, chemotherapy is defined as “a drug treatment that uses powerful chemicals to kill fast-growing cells in your body”, which unfortunately can include healthy non-cancerous cells. Erlotinib, therefore, is not chemotherapy. Unlike chemotherapy, erlotinib targets specific cancer surface markers exclusively.

How Erlotinib Is Taken

This medication is taken orally once daily and should be taken on an empty stomach, at least 1 hour before or 2 hours after food. It is also preferable to take the medication at the same time every day. If a patient misses a dose, they should take it as soon as they remember. If it is close to the timing of the next dose, the missed dose should be skipped and the patient should continue with the next dose at the scheduled time. Do not take two doses at once or extra doses. 

Dosage

Erlotinib comes in three strengths, as 25 mg, 100 mg, and 150 mg tablets.

The recommended dose for NSCLC is 150 mg/day. The recommended dose for pancreatic cancer is 100 mg/day.

The dose will be reduced in 50 mg increments when necessary.

Erlotinib Side Effects

The most common side effects in maintenance treatment are:

• Rash-like events
• Diarrhea

The most common side effects when this medication is used in 2nd line NSCLC are:

• Rash
• Diarrhea
• Anorexia
• Fatigue
• Dyspnea
• Cough
• Nausea
• Infection
• Vomiting

The most common side effects when this medication is used in pancreatic cancer are:

• Fatigue
• Rash
• Nausea
• Anorexia
• Diarrhea
• Abdominal pain
• Vomiting
• Weight loss
• Infection
• Edema
• Fever
• Constipation
• Bone pain
• Shortness of breath
• Mouth sores
• Muscle pain

Drug Interactions 

The blood level of this medication is affected by certain foods and medications. Therefore, the following should be avoided or a dose reduction should be considered if severe adverse reactions occur: 

• Atazanavir
• Clarithromycin
• Indinavir
• Itraconazole
• Ketoconazole
• Nefazodone
• Nelfinavir
• Ritonavir
• Saquinavir
• Telithromycin
• Troleandomycin (TAO)
• Voriconazole
• Grapefruit or grapefruit juice. 

Cigarette smoking can reduce erlotinib levels. Patients should therefore stop smoking while taking this medication. However, if they continue to smoke, a cautious increase in dose may be considered. 

Drugs that alter the pH of the upper GI tract may alter the solubility of erlotinib and reduce its effects. Coadministration of erlotinib with omeprazole (a proton pump inhibitor) can decrease erlotinib’s concentration so this combination should be avoided if possible. If patients need to be treated with a H2-receptor antagonist (i.e., ranitidine), erlotinib must be taken once a day, 10 hours after the H2-receptor antagonist dosing, and at least 2 hours before the next dose of the H2-receptor antagonist. Although the effect of antacids on erlotinib has not been evaluated, the antacid and erlotinib use should be separated by several hours, if an antacid is necessary.

Erlotinib Use In Pregnancy

This medication can cause fetal harm when administered to a pregnant woman. Women of childbearing potential should be advised to avoid pregnancy while on erlotinib. Adequate contraceptive methods should be used during therapy and for at least 2 weeks after completing therapy. 

Pricing

The cash price ranges from $1,600 to $10,000 for 30 tablets [3]. There are copay assistance programs and if a patient qualifies, it can greatly reduce the cost for the patient. Contact AmeriPharma™ to explore copay assistance programs.