Strategies to Overcome Acquired Resistance to EGFR-TKI Therapy Based on T790M Specific Substances using Osimertinib as an Example

Tyrosine kinase inhibitors (TKIs) of the epidermal growth factor receptor (EGFR) are widely used in non-small cell lung cancer patients harboring activating EGFR mutations. However, resistance mechanisms, particularly the T790M mutation, hamper longer-term therapeutic success of first and second generation EGFR-TKIs. To address this unmet medical need, EGFR-TKIs of the third generation are under clinical development. Relevant clinical efficacy with mainly mild to moderate class-specific side effects has been shown for third-generation EGFR-TKIs. Molecular testing is of major importance in deciding for treatment with third generation EGFR-TKIs. This article elucidates the developmental state of third generation EGFR-TKIs with its focus on Osimertinib, the first and currently the only compound in this class which is approved in Germany. Additionally, the medical importance of molecular diagnosis using tumor tissue and circulating tumor DNA is discussed