Metastatic lung cancer is cancer that originated in the lungs and has spread to distant organs. It tends to go wherever the blood goes, including the liver, the bones, elsewhere in the lungs, and the brain. It is, alas, not curable. Still, chemotherapy and targeted therapies offer the possibility of improved quality of life, and can lengthen life as well. Hot off the press is news that the US FDA has approved a targeted therapy (erlotinib, also known as Tarceva) for the treatment of patients whose cancers have spread and who in addition have tumors that have something known as an epidermal growth factor receptor EGFR) mutation. Let’s take a closer look at this fascinating EGFR protein. There is a family of glycoproteins that poke out of the cell surface like antennae. We call them HER1, HER2, HER3, and HER4. In some patients with lung cancer, the HER1 is over expressed; there are too many of them. When the growth signal hits the EGFR receptor, it causes it to join arms with other HER family members, fueling the growth of the cell. Erlotinib (a pill) targets the EGFR.
On May 14, 2013, the US Food and Drug Administration (FDA) approved the use of a drug that targets the EGFR receptor. Here’s why the FDA took the step: A randomized, multicenter trial compared erlotinib (86 patients) to the more commonly used combination of a platinum chemotherapy drug with another drug (we call this a platinum doublet). All patients had to have an EGFR mutation.
The majority of the patients were female (72%), Caucasian (99%), never-smokers (69%), and had adenocarcinoma histology (93%). The median progression free survival (half of patients had progression by this point, half did not) was 5.2 months in the platinum doublet chemotherapy arm, and 10.4 months in the erlotinib arm. And the survival was a bit better with erlotinib, too: 22.9 months versus 19.5 months. The majority of the patients in the platinum-based chemotherapy arm (82%) subsequently received an EGFR tyrosine kinase inhibitor following investigator-determined disease progression.
What’s the downside of erlotinib? The most frequent (greater than or equal to 30%) adverse reactions of any grade in the erlotinib arm were rash, diarrhea, asthenia, cough, dyspnea and decreased appetite. The most frequent (greater than or equal to 5%) grade 3-4 (bad) adverse reactions in the erlotinib arm were rash and diarrhea. The recommended daily dose of erlotinib for NSCLC is 150 mg taken orally at least one hour before or two hours after the ingestion of food. Treatment should continue until disease progression or unacceptable toxicity.
Thank you for visiting. I’m Dr. Michael Hunter.
Coming later this month: Understand Lung Cancer in 60 Minutes, an e-book for IPad.