P3.13-15 First-Line Afatinib Dose Initiation and Adjustment in Patients with EGFR Mutant Advanced Non-Small Cell Lung Cancer

Abstract

Background: The recommended starting dose of afatinib is 40mg od with 20mg, 30mg and 50mg tablets available for dose adjustment. Method: This is a retrospective observational study of starting dose, dose adjustment and optimal dose of first-line afatinib in patients withEGFR mutant advanced non-small cell lung cancer in University Malaya Medical Center from 1st December 2014 to 30th April 2018. Result: Of 22 patients on first-line afatinib, the starting dose was 40 mg od in 12 patients and 30 mg od in 10 patients (Figure 1). Among the 12 patients started on afatinib 40mg od, 4 (33.3%) did not require dose adjustment, 4 (33.3%) needed dose reduction to 30mg od, 2 (16.7%) needed dose reduction to 20mg od, and 2 (16.7%) had dose escalation to 50mg od. Among 10 patients started on afatinib 30mg od, 6 (60%) did not require dose adjustment, 1 (10%) needed dose reduction to 25mg od and 3 (30%) had dose escalation to 40mg od. Dose reduction was to reduce the cost of treatment in 1 patient and to reduce drug related side-effects in the rest. Dose escalation was exclusively to improve disease control. The overall response rate and disease control rate was 80% (8/10) and 90% (9/10) in patients who did not require dose adjustment; while the respective rates were 85.7% (6/7) and 100% (7/7) in patients who had dose reduction. The optimal dose of afatinib defined by good disease control and tolerable side-effects was 50mg od in 9.1% (2/22), 40mg od in 31.8% (7/22), 30mg od in 31.8% (7/22), 25mg od in 13.6% (3/22) and 20mg od in 13.6% (3/22) of patients. Conclusion: We suggest starting afatinib at 30mg od and adjust the dose accordingly because dose adjustment is not required in most cases on this starting dose and it is the commonest optimal dose.