Clinical Experience With 75-mg Dose of Erlotinib for Mutated Metastatic EGFR Non-small Cell Lung Cancer

Background: Non-small cell lung cancer (NSCLC) remains the leading cause of cancer death worldwide, although important advances in target therapy have been developed in the past few years. Erlotinib is a reversible epidermal growth factor receptor (EGFR) inhibitor, which was approved at its maximum tolerated dose of 150 mg/d determined from the initial phase I study. Studies suggest that the optimal biological dose of erlotinib should be lower and dependent on different variables. Study Question: We aimed to evaluate the response rates and toxicity with 75 mg/d dose of erlotinib in South American patients. Method: We performed a retrospective review of 18 patients with histologically proven (+) EGFR (+) mutation metastatic NSCLC (mNSCLC) treated with 75 mg/d erlotinib as starting dose. Measures and Outcomes: Clinical information, including toxicity grade 1-4, drug discontinuation, clinical evolution and radiological evaluation, and overall survival (OS), was revised. Results: Patients received 75 mg/d of erlotinib as starting dose. Sixteen (89%) patients were treated in first-line treatment and 2 (11%) in second-line treatment. Mean age was 62 years (range 36-89 years), and 50% patients were female. Sixteen percent of the patients had brain metastases at first diagnosis. All patients had mutation positive EGFR, 12 (66%) had Del19 and 6 (34%) exon 21 mutation. Median progression-free survival was 17 months and OS 23 months. The main grade 1-2 toxicities were rash (44%) and diarrhea (22%). No grade 3-4 toxicity and no cases of drug discontinuation were reported. Conclusions: In South American population with mutated mNSCLC, a dose of 75 mg/d of erlotinib was well tolerated. This dose resulted in comparable benefits in progression-free survival and OS when compared to those reported in the literature with the standard dose. More studies are needed to explore the use of adjusted doses of biological agents in different ethnic backgrounds.