Pharmacovigilance and Mechanistic Analysis of Adverse Reaction Differences Across EGFR Tyrosine Kinase Inhibitor Generations in Non-Small Cell Lung Cancer

Background

Epidermal Growth Factor Receptor (EGFR) tyrosine kinase inhibitors (TKIs) are widely used for EGFR-mutated non-small cell lung cancer (NSCLC) but have distinct toxicity profiles across generations.

Aims

To investigate relationships between EGFR-TKI physicochemical, pharmacokinetic and pharmacological properties and drug-specific adverse drug reactions (ADRs) using national and global pharmacovigilance data.

Methods

ADRs for erlotinib, afatinib and osimertinib were extracted from the UK MHRA Yellow Card scheme and WHO VigiAccess. Disproportionality analysis used reporting odds ratios (RORs). Signals were defined as ROR ≥2, lower 95% confidence interval >1 and ≥3 cases. Drug properties were curated from ChEMBL, emc, SmPC and EMA sources.

Results

VigiAccess contained 88,662 individual case safety reports (163,619 ADRs) and Yellow Card contained 752 reports (1,814 ADRs). Four System Organ Class (SOC) signals were identified in VigiAccess and three in Yellow Card, with five additional Yellow Card Preferred Term signals. Eye disorders showed the strongest consistent association with erlotinib (VigiAccess ROR 4.33; Yellow Card ROR 4.18). Osimertinib was associated with pneumonitis (ROR 7.67) and pulmonary embolism (ROR 3.94). Afatinib showed psychiatric disorder signals in both databases (ROR 3.2– 3.3) and diarrhoea (ROR 2.79). Neoplasm-related signals likely reflected confounding by indication.

Conclusions

EGFR-TKIs demonstrate generation-specific pharmacovigilance profiles. Integration with drug properties supports mechanistic plausibility for several signals, while the atypical afatinib psychiatric association warrants further investigation. Findings are hypothesis-generating and require confirmation in controlled observational or mechanistic studies.

What is already known about this subject?

• First-, second-and third-generation EGFR-TKIs (erlotinib, afatinib and osimertinib) are established treatments for EGFR-mutated NSCLC but are associated with distinct adverse drug reaction (ADR) profiles that differ across generations.

• Known class-effect toxicities include dermatological, gastrointestinal, and ocular ADRs, attributed to EGFR inhibition in non-tumour epithelial tissues.

• Prior pharmacovigilance studies using the US FDA Adverse Event Reporting System (FAERS) have characterised EGFR-TKI safety signals, but UK-specific Yellow Card data have not been systematically analysed across all three generations, and the pharmacological basis for generation-specific differences remains incompletely understood.

What this study adds

• Dual-database disproportionality analysis of MHRA Yellow Card and WHO VigiAccess data, using a pre-specified signal threshold (ROR ≥ 2, lower 95% CI > 1, n ≥ 3), confirmed generation-specific signals: eye disorders for erlotinib; psychiatric disorders and diarrhoea for afatinib; and pneumonitis and pulmonary embolism for osimertinib.

• Integration of target potency (pIC50), ErbB family selectivity, blood brain barrier (BBB) penetration and CYP ₄₅₀ interaction data with the pharmacovigilance signals provides mechanistic plausibility, linking them to variations in binding reversibility, wild-type EGFR inhibition, and off-target kinase activity.

• Applying a pre-specified, conservative signal threshold distinguished genuine disproportionate signals from elevated but non-significant reporting and identified neoplasm-related findings as confounded by indication rather than true drug safety signals highlighting the importance of rigorous signal definition in oncology pharmacovigilance.