OBJECTIVES: Afatinib, erlotinib and gefitinib are epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs). They are indicated for the treatment of non-small cell lung cancer (NSCLC) with activating EGFR mutations. Erlotinib is also indicated for pancreatic cancer. Erlotinib, gefitinib and afatinib have been reimbursed in Ireland since 2006, 2011 and 2014 respectively. This work aims to describe prescribing trends across EGFR-TKIs in Ireland. It is anticipated that the patent for erlotinib will expire in 2020; the potential cost saving implications of this are examined.

METHODS:Anonymised prescription claims data obtained from the Primary Care Reimbursement Service (January 2006 to April 2019) were analysed using R. The following variables were examined: market share (MS), treatment sequencing and number of patients treated per year.

RESULTS: Until 2011 erlotinib held 100%of the MS for EGFR-TKIs. Following the launch of gefitinib in 2011 the MS of erlotinib decreased to 91% by 2013. In 2014, afatinib reduced the MS held by erlotinib and gefitinib by 3% and 5% respectively. In 2017 the MS for erlotinib was 71% and the annual expenditure was reported to be €1,218,666. It was found that only 3% patients received sequential EGFR-TKIs, with afatinib followed by erlotinib the most common sequence (N=40).The lowest number of patients (N=150) were treated with an EGFR-TKI in 2018.

CONCLUSIONS: Erlotinib was found to dominate the market share each year despite the subsequent launch of gefitinib and afatinib. A limitation of this study is that the MS reported included patients prescribed EGFR-TKIs for conditions other than NSCLC. The availability of generic erlotinib is likely to result in significant cost savings with the price expected to fall to 50% of the original ex-factory price. However, the upcoming availability of third generation EGFR inhibitors as first–line treatment in NSCLC may have substantial impact on the majority MS currently held by erlotinib.