Dynamic changes of acquired T790M mutation and small cell lung cancer transformation in a patient with EGFR-mutant adenocarcinoma after first- and third-generation EGFR-TKIs: a case report

[Advances of Molecular Targeted Therapy in EGFR-mutated Squamous Cell Lung Cancer]

Non-small cell lung cancer (NSCLC) is a prevalent tumour type in our country, with lung squamous carcinoma being a commonly observed NSCLC subtype besides lung adenocarcinoma. Epidermal growth factor receptor (EGFR) is a significant driver gene in lung cancer, and EGFR mutation frequency is considerably lower in lung squamous carcinoma in comparison to lung adenocarcinoma. Although targeted therapy against EGFR has demonstrated significant advancements in lung adenocarcinoma, while progress in lung squamous carcinoma has been relatively sluggish. This paper reviews recent studies on molecular targeted therapy for EGFR-mutated lung squamous carcinoma and summarises the efficacy of EGFR-tyrosine kinase inhibitors (TKIs) in treating squamous carcinoma of the lung, in order to provide a reference for treating patients with EGFR-mutated squamous carcinoma of the lung.
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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.

Genomic and immunological profiles of small-cell lung cancer between East Asians and Caucasian

The characterization of immunological and genomic differences in small-cell lung cancer (SCLC) between East Asian (EA) and Caucasian patients can reveal important clinical therapies for EA patients with SCLC. By sequencing and analyzing a molecular and immunological dataset of 98-SCLC patients of EA ancestry, immunogenicity, including DNA damage repair alterations and tumor mutation burden (TMB), was found to be significantly higher in the EA cohort than in the Caucasian cohort. The epithelial-mesenchymal transition (EMT) was the signaling signature with the predominant frequency of mutations across all patients in the EA cohort. Analysis of tumor-infiltrated immune cells revealed that resting lymphocytes were significantly enriched in the EA cohort. Compound-targeting analysis showed that topoisomerase inhibitors might be capable of targeting TP53 and RB1 comutations in EA SCLC patients. EA SCLC patients who harbored COL6A6 mutations had poor survival, while Caucasian SCLC patients with OTOF, ANKRD30B, and TECPR2 mutations were identified to have a shorter survival.

Outcomes in Patients With Lung Adenocarcinoma With Transformation to Small Cell Lung Cancer After EGFR Tyrosine Kinase Inhibitors Resistance: A Systematic Review and Pooled Analysis

Background

Lung adenocarcinoma can transform into small-cell lung cancer (SCLC) when resistance to tyrosine kinase inhibitors (TKIs) develops. Approximately 3% to 10% of epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) could transform to SCLC. This phenomenon has been described in several case reports and small patient series. However, the characteristics and treatment outcomes of this population have not been comprehensively reported, and their clinical course is poorly characterized.

Methods

We performed a systematic review of the published literature to summarize the clinical and pathological features and prognosis of the reported cases and analyzed the demographics, disease features, and outcomes.

Results

A total of 72 patients (50 females and 22 males) initially diagnosed with lung adenocarcinoma were included. EGFR mutations included 19-deletion (75%), L858R (22%), and G719X (3%). All patients received EGFR-TKIs before SCLC transformation. The median time from diagnosis to transformation was 20.5 months (95% CI, 15.45 to 26.55 months). Of the 67 patients with post-translational gene test results, 58 maintained their EGFR mutation, and only 1 of 18 with prior T790M positivity retained T790M mutation. After the pathological transformation, both conventional chemotherapy regimen and chemotherapy combined targeted therapy yielded high response rates. The disease control rate of first-line therapy after transformation was 76%, while the objective response rate was 48%. The median overall survival (OS) since diagnosis was 27 months (95% CI, 22.90 to 31.10 months), whereas median OS since SCLC transformation was 8.5 months (95% CI, 5.50 to 11.60 months).

Conclusion

The prognosis of transformed SCLC is worse than primary SCLC. The response rate to conventional chemotherapy was high. However, the progression-free survival and OS after transformation were short and the prognosis was poor with first-line therapies. New therapies are needed in the management of transformed SCLC.

Resistance mechanisms to osimertinib and emerging therapeutic strategies in nonsmall cell lung cancer

PURPOSE OF REVIEW

This review aims to introduce the resistance mechanisms to osimertinib, discuss the therapeutic strategies, and make clinical updates in overcoming resistance to osimertinib.

RECENT FINDINGS

Osimertinib has shown favorable efficacy on second-line and first-line treatments in EGFR-mutant advanced nonsmall cell lung cancer (NSCLC). However, the presence of primary and acquired resistance to osimertinib restricts its clinical benefits. The primary resistance mainly consists of BIM deletion polymorphism and EGFR exon 20 insertions. Meanwhile, the heterogeneous mechanisms of acquired resistance include EGFR-dependent (on-target) and EGFR-independent (off-target) mechanisms. EGFR C797S mutation, MET amplification, HER2 amplification, and small cell lung cancer transformation were identified as frequent resistance mechanisms. Recently, more novel mechanisms, including rare EGFR point mutations and oncogenic fusions, were reported. With the results of completed and on-going clinical trials, the emerging therapeutic strategies of postosimertinib progression are summarized.

SUMMARY

The resistance mechanisms to osimertinib are heterogeneous and gradually perfected. The combination of osimertinib with bypass targeted therapy and other therapeutic approaches emerge as promising strategies.

Novel ETV1 mutation in small cell lung cancer transformation resistant to EGFR tyrosine kinase inhibitors

Background

Non-small cell lung cancer (NSCLC) patients harboring mutations in the epidermal growth factor receptor (EGFR) gene respond dramatically to EGFR tyrosine kinase inhibitors (TKIs). However, these patients inevitably develop acquired resistance to EGFR-TKIs. Among them, small cell lung cancer (SCLC) transformation is a relatively rare mechanism.

Methods

We used a 639 cancer-relevant gene panel to detect genetic differences in tissues before and after EGFR-TKIs resistance caused by SCLC transformation. In vitro experiments were conducted to study the role of ETS variant transcription factor 1 (ETV1) on SCLC transformation and EGFR-TKIs resistance.

Results

We present two EGFR-mutant lung adenocarcinoma (LUAD) patients. One patient, with EGFR exon 19 deletion (Ex19del), accepted first-line gefitinib treatment and then received osimertinib treatment due to acquisition of an EGFR-T790M mutation. A novel ETV1 mutation (p.P159S) was detected in the SCLC tissue after osimertinib resistance when not coexisting with T790M. The other patient harbored an EGFR exon 21 mutation (p.L858R), and had a long-lasting response to first-line gefitinib, and then transformed to SCLC after TKI resistance. A previously unreported ETV1 mutation (p.E462Q) was detected in the SCLC tissue. In vitro, ETV1 p.E462Q and p.P159S mutations participated in neuroendocrine differentiation by inducing the expression of achaete-scute homolog 1 (ASCL1) and promoting the proliferation of H69 cells. ETV1 p.E462Q and p.P159S mutations were also resistant to gefitinib and osimertinib after introduction into H358 cells.

Conclusions

Novel ETV1 p.E462Q and p.P159S mutations were found in the SCLC tissues of TKIs-resistant LUAD patients, providing a new understanding of ETV1 involvement in acquired resistance to EGFR-TKIs via SCLC transformation.