Project description:First-generation epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), including gefitinib and erlotinib, have proven to be highly effective agents for advanced non-small cell lung cancer (NSCLC) in patients harboring an activating EGFR mutation such as the exon 19 deletion mutation and L858R. Although those reversible small molecular targeted agents provide a significant response and survival benefit, all responders eventually acquire resistance. Second-generation EGFR-targeting agents, such as irreversible EGFR/HER2 tyrosine kinase inhibitors and pan-HER TKIs, may improve survival further and be useful for patients who acquired resistance to first-generation EGFR-TKIs. This review discusses novel therapeutic strategies for EGFR-mutated advanced NSCLC using first- and second-generation EGFR-TKIs.
Project description:Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) represent the standard of care for advanced non-small cell lung cancer (NSCLC) patients whose tumours harbor an activating EGFR mutation. Unfortunately, resistance to first- and second-generation EGFR-TKIs inevitably occurs in all patients with EGFR-mutant disease approximately within a year of treatment. At least half of these cases are attributed to the emergence of a secondary mutation in exon 20 of the EGFR gene, namely the T790M mutation. Third-generation EGFR-TKIs, including osimertinib and rociletinib, target this epigenic mutation, thus re-sensitizing cancer cells to EGFR-TKI inhibition. Osimertinib to date represents the standard of care in EGFR-mutant tumors after failure of first-line EGFR-TKIs by over-performing platinum-based chemotherapy in the recently reported AURA-3 randomized phase III clinical trial. The aim of this review is to describe the different treatment strategies that have been developed to reverse resistance to first- and second-line EGFR-TKIs, the corresponding mechanisms of resistance and the development of novel-generation EGFR-TKIs. We also discuss the challenge posed by the implementation of third-generation EGFR-TKIs earlier in the course of the disease in first-line treatment of EGFR-mutant NSCLC.
Project description:Sensitizing mutations in the epidermal growth factor receptor (EGFR) predict response to EGFR tyrosine kinase inhibitors (TKIs) and both first- and second-generation TKIs are available as first-line treatment options in patients with advanced EGFR-mutant non-small cell lung cancer. Eventual resistance develops with multiple mechanisms identifiable both upon repeat biopsy and in plasma circulating tumor DNA. The T790M gatekeeper mutation is responsible for almost 60% of cases. A number of third-generation TKIs are in clinical development, and osimertinib has been approved by the US Food and Drug Administration for the treatment of patients with EGFR T790M mutant lung cancer after failure of initial EGFR kinase therapy. Resistance mechanisms are being identified to these novel agents, and the treatment landscape of EGFR-mutant lung cancer continues to evolve. The sequence of EGFR TKIs may change in the future and combination therapies targeting resistance appear highly promising.
Project description:In recent years, targeted therapy and immunotherapy have played important roles in the treatment of patients with non-small-cell lung cancer (NSCLC). Drugs that target epidermal growth factor receptor (EGFR) mutations (eg, gefitinib, erlotinib, icotinib, and osimertinib) are among the most commonly used targeted therapies. Afatinib is an irreversible second-generation EGFR-tyrosine kinase inhibitor (EGFR-TKI), and the LUX-Lung 3 trial demonstrated the superiority of afatinib to cisplatin and pemetrexed in the frontline treatment of treatment-naïve patients with advanced EGFR mutation adenocarcinoma of the lung. Although these drugs show significant therapeutic efficacy, most patients invariably experience disease progression resulting in death. Immunotherapy targeting programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) has now been approved for the first-line treatment of patients with advanced NSCLC. These can produce sustained clinical responses by reversing negative regulators of T-cell function; however, immunotherapy response rates remain low, and only a few patients ultimately benefit from this approach. Here, we discuss the potential of EGFR-TKIs for inducing antitumor immunity and the feasibility of their combination with immunotherapy (including PD-1/PD-L1 inhibitors) in NSCLC patients and the associated challenges for clinical application.
Project description:Most advanced non-small-cell lung cancers (NSCLCs) with activating epidermal growth factor receptor (EGFR) mutations (exon 19 deletions or L858R) initially respond to the EGFR tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib. However, over time (median of 6-12 months), most tumors develop acquired resistance to EGFR TKIs. Intense research in these NSCLCs has identified two major mechanisms of resistance to gefitinib/erlotinib: secondary resistance mutations and "oncogene kinase switch" systems. The secondary T790M mutation occurs in 50% of EGFR-mutated patients with TKI resistance, and in vitro, this mutation negates the hypersensitivity of activating EGFR mutations. Sensitive detection methods have identified a proportion of TKI-naive tumors that carry T790M, and these resistant clones may be selected after exposure to gefitinib or erlotinib. Other secondary resistance mutations (D761Y, L747S, T854A) seem to be rare. The amplification of the MET oncogene is present in 20% of TKI-resistant tumors; however, in half of the cases with this "oncogene kinase switch" mechanism the T790M is coexistent. It is possible that other kinases (such as insulin-like growth factor-1 receptor [IGF-1R]) might also be selected to bypass EGFR pathways in resistant tumors. The growing preclinical data in EGFR-mutated NSCLCs with acquired resistance to gefitinib or erlotinib has spawned the initiation or conception of clinical trials testing novel EGFR inhibitors that in vitro inhibit T790M (neratinib, XL647, BIBW 2992, and PF-00299804), MET, or IGF-1R inhibitors in combination with EGFR TKIs, and heat shock protein 90 inhibitors. Ongoing preclinical and clinical research in EGFR-mutated NSCLC has the potential to significantly improve the outcomes of patients with these somatic mutations.
Project description:EGFR mutations identify patients who are more likely to respond to treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) than cytotoxic chemotherapy. The distinct success of the first-generation EGFR TKIs erlotinib and gefitinib has been accompanied by the observation that acquired resistance to these treatments develops after a median of 1 year of treatment. Newer, second-generation EGFR TKIs have been developed with the intent to delay or overcome acquired resistance by the broader inhibition of kinases (eg, HER2 and vascular endothelial growth factor receptor) and/or altering the interactions with EGFR through irreversibly binding to the kinase domain. This article discusses many of these agents (including afatinib, dacomitinib, XL647, AP26113, and CO-1686) which have the potential for greater efficacy compared with first-generation EGFR TKIs, and may also have clinical activity against other oncogenic mutations within the EGFR family, including HER2.
Project description:Most patients with non-small cell lung cancer (NSCLC) harboring common epidermal growth factor receptor (EGFR) mutations, such as deletions in exon 19 or the L858R mutation in exon 21, respond dramatically to EGFR tyrosine kinase inhibitors (EGFR-TKI), and their sensitivities to various EGFR-TKI have been well characterized. Our previous article showed the in vitro sensitivities of EGFR exon 18 mutations to EGFR-TKI, but little information regarding the sensitivities of other uncommon EGFR mutations is available. First, stable transfectant Ba/F3 cell lines harboring EGFR L858R (Ba/F3-L858R), L861Q (Ba/F3-L861Q) or S768I (Ba/F3-S768I) mutations were created and their drug sensitivities to various EGFR-TKI were examined. Both the Ba/F3-L861Q and Ba/F3-S768I cell lines were less sensitive to erlotinib, compared with the Ba/F3-L858R cell line, but their sensitivities to afatinib were similar to that of the Ba/F3-L858R cell line. The Ba/F3-L861Q cell line was similarly sensitive and the Ba/F3-S768I cell line was less sensitive to osimertinib, compared with the Ba/F3-L858R cell line. The results of western blot analyses were consistent with these sensitivities. Next, similar experiments were also performed using the KYSE270 (L861Q) and KYSE 450 (S768I) cell lines, and their results were compatible with those of the transfectant Ba/F3 cell lines. Our findings suggest that NSCLC harboring the EGFR L861Q mutation might be sensitive to afatinib or osimertinib and that NSCLC harboring the EGFR S768I mutation might be sensitive to afatinib. Overall, afatinib might be the optimal EGFR-TKI against these uncommon EGFR mutations.
Project description:Mutations in the epidermal growth factor receptor (EGFR) gene are the most common targetable genomic drivers of non-small cell lung cancer (NSCLC), occurring in approximately 50% and 10-15% of adenocarcinomas of the lung in Asian and Western populations, respectively. The most common EGFR-activating mutations, the exon 19 deletion and the L858R point mutation occurring in the receptor tyrosine kinase domain, are susceptible to inhibition. The first EGFR tyrosine kinase inhibitors (TKIs) to be evaluated were the reversible first-generation EGFR TKIs, gefitinib and erlotinib, followed by the irreversible second-generation EGFR TKIs, afatinib and dacomitinib. The study of acquired resistance mechanisms to first- and second-generation EGFR TKIs in patients with activating EGFR-mutated NSCLC identified the gatekeeper T790M point mutation, present in over 50% of cases, as the most common mechanism of acquired resistance. The need to overcome this resistance mechanism led to the development of third-generation EGFR TKIs, of which osimertinib is the only one to date with regulatory approval. In this review, we present the clinical context leading to the development of third-generation EGFR TKIs, the mode of action of these inhibitors and the clinical data supporting their use. We review third-generation TKI agents that are approved, in development, and those that failed in clinical trials. Finally, we will touch upon ongoing studies and future directions, such as combination treatment strategies, currently being explored to improve the efficacy of treatment with third-generation EGFR TKIs.