Acquisition of T790M resistance mutation in a patient with advanced adenocarcinoma harbouring uncommon EGFR mutations: a case report and literature review

Adaptive therapy to circumvent drug resistance to tyrosine kinase inhibitors in cancer: is it clinically relevant?

INTRODUCTION

Cancer is highly adaptable and is constantly evolving against current targeted therapies such as tyrosine kinase inhibitors. Despite advances in recent decades, the emergence of drug resistance to tyrosine kinase inhibitors constantly hampers therapeutic efficacy of cancer treatment. Continuous therapy versus intermittent clinical regimen has been a debate in drug administration of cancer patients. An ecologically-inspired shift in cancer treatment known as 'adaptive therapy' intends to improve the drug administration of drugs to cancer patients that can delay emergence of drug resistance.

AREAS COVERED

We discuss improved understanding of the concept of drug resistance, the basis of continuous therapy, intermittent clinical regimens, and adaptive therapy will be reviewed. In addition, we discuss how adaptive therapy provides guidance for future cancer treatment.

EXPERT OPINION

The current understanding of drug resistance in cancer leads to poor prognosis and limited treatment options in patients. Fighting drug resistance mutants is constantly followed by new forms of resistance. In most reported cases, continuous therapy leads to drug resistance and an intermittent clinical regimen vaguely delays it. However, adaptive therapy, conceptually, exploits multiple parameters that can suppress the growth of drug resistance and provides safe treatment for cancer patients in the future.

Efficacy and potential resistance mechanisms of afatinib in advanced non-small cell lung cancer patients with EGFR G719X/L861Q/S768I

BACKGROUND

Afatinib is the only currently approved EGFR-tyrosine kinase inhibitors for advanced non-small cell lung cancer (NSCLC) patients with EGFR G719X/L861Q/S768I. However, there are limited real-world data concerning the benefits and resistance mechanisms of afatinib in patients with these nonclassical mutations. To fill this gap, the present study was conducted.

METHODS

All NSCLC patients treated with afatinib were screened, and patients with EGFR G719X/L861Q/S768I were enrolled into the analysis. Either tumor tissue or blood specimens were detected by the commercial next-generation sequencing (NGS) panels or amplification-refractory mutation system (ARMS)-polymerase chain reaction (PCR) to figure out the mutation genotype.

RESULTS

A total of 106 advanced NSCLC patients with EGFR G719X/L861Q/S768I received afatinib treatment. The benefits of afatinib exhibited heterogeneity in different mutation genotypes. Notably, at baseline, NGS testing was performed in 59 patients, and TP53 was the most frequently coexisting mutation. Patients with TP53 mutations obtained fewer survival benefits than those with TP53 wild-type. A total of 68 patients ultimately experienced progression, and 27 patients received NGS testing to clarify the potential resistance mechanisms. EGFR-T790M, CDK4 amplification, FGFR1 amplification, PIK3CA, MET amplification, RET fusions, HER2, and BRAF mutations were identified in three (11.1%), three (11.1%), three (11.1%), three (11.1%), three (11.1%), one (3.7%), one (3.7%), and one (3.7%) of the cases, respectively. Five patients underwent ARMS-PCR testing for detecting EGFR-T790M mutation, and only one patient was T790M-positive.

CONCLUSIONS

The present study elucidated the differential benefits of afatinib within different mutation genotypes and first revealed the spectrum of potential resistance mechanisms in patients with EGFR G719X/L861Q/S768I. The results of this study may provide practical clinical information that can guide optimal treatment in this setting.

Uncommon EGFR mutations conducted with osimertinib in patients with NSCLC: a study protocol of phase 2 study (UNICORN/TCOG1901)

Patients with uncommon EGFR-mutated non-small-cell lung cancer (NSCLC) demonstrated lower clinical efficacy of first-generation EGFR-tyrosine kinase inhibitors compared with patients harboring common EGFR-mutated NSCLC. The US FDA has approved afatinib for uncommon EGFR mutation positive NSCLC based on the pooled analysis in the first- or second-line setting. Osimertinib has limited evidence in the small sample sizes of phase 2 studies in any-line settings. The aim of the present single-arm, multicenter, phase 2 study is to evaluate the efficacy of osimertinib for previously untreated NSCLC. The primary end point is to assess the overall response to osimertinib. The secondary end points include disease control rate, progression-free survival, duration of time-to-treatment failure, overall survival and safety. Clinical trial registration: jRCTs071200002.

Study of patient characteristics, treatment patterns, EGFR testing patterns and outcomes in real-world patients with EGFRm+ non-small cell lung cancer

OBJECTIVE

This retrospective, observational study examined patient characteristics, treatment patterns, testing patterns, and outcomes of US patients receiving first-/second- or third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs).

METHODS

This study used an electronic health record-derived de-identified database. Eligible patients had advanced EGFRm⁺ non-small cell lung cancer. Descriptive statistics were used to describe demographic, clinical, and treatment characteristics. Logistic regression models were used to identify patient characteristics that were associated with the use of osimertinib vs. a first-/second-generation EGFR TKI. Kaplan-Meier methods were used for survival analysis.

RESULTS

Of the 782 patients who received first-line (1L) therapy with first-/second-generation EGFR TKIs in cohort A, erlotinib was the most common (58%), and osimertinib was the most widely prescribed second-line (2L) therapy (52%). Of the patients who received 1L therapy with osimertinib, a greater range of treatments were prescribed in 2L. A third of patients treated with first-/second-generation EGFR TKIs underwent EGFR testing near the end of 1L, and 44% of these patients had T790M positive disease. The median time on targeted therapy (TTT) of the cohort was 11.1 months (95% confidence interval [CI] 9.7, 12.3), and the median overall survival from the start of 1L therapy was 23.5 months (95% CI 20.7, 24.8).

CONCLUSIONS

The majority of patients treated with first-/second-generation EGFR TKIs went on to receive osimertinib in the 2L setting, but overall, only a third of patients had received molecular testing at progression. Improved testing frequency is vital to inform treatment decisions.

Generation of osimertinib-resistant cells from epidermal growth factor receptor L858R/T790M mutant non-small cell lung carcinoma cell line

BACKGROUND

Lung cancer contributes to high cancer mortality worldwide with 80% of total cases diagnosed as non-small cell lung cancer (NSCLC). Epidermal growth factor receptor (EGFR) tyrosine kinase (TK) domain serves as a druggable target in NSCLC patients with exon 19 deletion and L858R mutation. However, patients eventually succumbed to resistance to first- and second-generation EGFR-TK inhibitors through activation of T790M mutation. Third-generation EGFR-TKI, Osimertinib exhibits high efficacy in patients with exon 19 deletion/L858R/T790M mutation but they experienced acquired resistance thereafter. Available treatment options in NSCLC patients remains a challenge due to unknown molecular heterogeneity responsible for acquired resistance to EGFR-TKI. In this study, we aim to generate Osimertinib-resistant (OR) cells from H1975 carrying L858R/T790M double mutation which can be used as a model to elucidate mechanism of resistance.

METHODS

OR cells were established via stepwise-dose escalation and limiting single-cell dilution method. We then evaluated Osimertinib resistance potential via cell viability assay. Proteins expression related to EGFR-signalling, epithelial to mesenchymal transition (EMT), and autophagy were analyzed via western blot.

RESULTS

OR cell lines exhibited increased drug resistance potential compared to H1975. Distinguishable mesenchymal-like features were observed in OR cells. Protein expression analysis revealed EGFR-independent signaling involved in the derived OR cells as well as EMT and autophagy activity.

CONCLUSION

We generated OR cell lines in-vitro as evidenced by increased drug resistance potential, increased mesenchymal features, and enhanced autophagy activity. Development of Osimertinib resistance cells may serve as in-vitro model facilitating discovery of molecular aberration present during acquired mechanism of resistance.

Uncommon EGFR mutations associate with lower incidence of T790M mutation after EGFR-TKI treatment in patients with advanced NSCLC

OBJECTIVES

Advanced non-small cell lung cancer (NSCLC) patients harboring non-resistant uncommon epidermal growth factor receptor (EGFR) mutations have stepped into the era of targeted therapy. This study aimed to investigate the incidence of acquired T790M mutation and their outcome to subsequent osimertinib in patients of advanced NSCLC harboring uncommon EGFR mutations.

PATIENTS AND METHODS

Patients with EGFR mutation and performed re-biopsy after progression on prior EGFR-tyrosine kinase inhibitors (TKIs) were reviewed and analyzed. Those with T790M mutation and received subsequent osimertinib treatment were further collected for survival analysis.

RESULTS

Finally, 754 patients, including 48 with uncommon mutation, 362 with 19del and 344 with L858R were enrolled. T790M mutation was identified in 341 patients (341/754, 45.2 %). The incidence of T790M mutation was 27.1 % in patients harboring uncommon mutations, significantly lower than 55.2 % and 37.2 % of 19del and L858R (p < 0.001). Logistic regression analysis further found uncommon mutation associated with significantly lower probability of developing T790M (odds ratio [OR] = 0.32, 95 % confidence interval [CI] 0.16-0.64). Among 236 patients received subsequent osimertinib treatment (including 12 uncommon mutation, 145 19del and 79 L858R), patients harboring uncommon mutations showed significantly shorter progression free survival (PFS) (median: 4.6 vs. 11.6 vs. 12.1 months, p < 0.001) and overall survival (OS) (median: 8.1 vs. 35.4 vs. 24.9 months, p = 0.001) compared with 19del and L858R, also associated with numerically lower objective response rate (ORR) (p = 0.085) and lower disease control rate (DCR) (p = 0.074). Multivariate analysis further found that uncommon mutation was the only one significantly associated with both PFS (hazard ratio [HR] = 3.44, 95 %CI 1.79-6.58) and OS (HR = 3.64, 95 %CI 1.66-7.99).

CONCLUSIONS

Uncommon EGFR mutation showed a significantly lower incidence of acquired T790M mutation and benefited significantly less from subsequent osimertinib treatment than common EGFR mutations in patients with advanced NSCLC.