Monitoring of the presence of EGFR-mutated DNA during EGFR-targeted therapy may assist in the prediction of treatment outcome

ctDNA SNORD3F Hypermethylation is a Prognostic Indicator in EGFR-TKI-Treated Advanced Non-Small Cell Lung Cancer

Purpose

DNA methylation plays a regulatory role in the oncogenesis and tumor progression and is valuable in the diagnosis and prognosis of cancer. While circulating tumor DNA (ctDNA) is widely used in the detection of oncogenic mutations and the guidance of treatment in advanced non-small cell lung cancer (NSCLC), studies of ctDNA methylation remains insufficient. We aim to investigate the methylation profiles of ctDNA in patients with advanced NSCLC undergoing EGFR-tyrosine kinase inhibitor (EGFR-TKI) therapy and to discover novel biomarkers with predictive or prognostic value.

Patients and Methods

We recruited 49 patients with EGFR-mutated advanced NSCLC undergoing EGFR-TKI as first-line treatment. Utilizing next-generation sequencing, we examined the somatic mutations and methylation signatures within the tumor-associated genomic regions of ctDNA from pre-treatment blood. Subsequently, we explored the association of these molecular features with the patients' response to therapy and their progression-free survival (PFS).

Results

Genomic mutation profiling revealed no significant association of PFS or best overall response (BOR) and ctDNA status. Evaluation of ctDNA methylation showed a negative correlation between the methylation of small nucleolar RNA (snoRNA) genes and PFS (R=-0.31, P=0.043). Furthermore, high-level methylation of SNORD3F was associated with poorer PFS (mPFS 346d vs 243d, HR 0.49, 95% CI 0.24-0.93, P=0.029).

Conclusion

Our study explored the prognostic value of ctDNA methylation in patients with advanced NSCLC undergoing targeted therapies and first revealed the predictive role of SNORD3F.

Epidermal growth factor receptor-mutated lung carcinomas with insufficient response to epidermal growth factor receptor inhibitors

Administration of single-agent epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) is a standard treatment option for metastatic non-small cell lung carcinomas with EGFR exon 19 deletions (ex19del) and L858R substitutions. However, there is a significant interpatient heterogeneity with regard to the degree of the response and its duration. Patients with EGFR ex19del mutation, TP53 wild-type, good performance status, low tumor burden and no circulating tumor DNA (ctDNA) at baseline have the best chances to derive pronounced benefit from TKI therapy. In contrast, subjects with EGFR L858R substitution, mutated TP53, poor overall condition, high tumor volume and detectable ctDNA are generally poor responders to EGFR inhibitors. ctDNA dynamics in the first days or weeks of treatment allows reliable identification of patients, who are very unlikely to derive clinically meaningful benefit from single-agent TKIs. These patients are candidates for clinical trials, which may involve the addition of chemotherapy and antiangiogenic drugs to patients, who failed to achieve immediate benefit from TKI monotherapy.

A Phase II Study of Osimertinib in Patients with Advanced-Stage Non-Small Cell Lung Cancer following Prior Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor (EGFR TKI) Therapy with EGFR and T790M Mutations Detected in Plasma Circulating Tumour DNA (PLASMA Study)

Epidermal growth factor receptor (EGFR) T790M mutations drive resistance in 50% of patients with advanced non-small cell lung cancer (NSCLC) who progress on first/second generation (1G/2G) EGFR tyrosine kinase inhibitors (TKIs) and are sensitive to Osimertinib. Tissue sampling is the gold-standard modality of T790M testing, but it is invasive. We evaluated the efficacy of Osimertinib in patients with EGFR mutant NSCLC and T790M in circulating tumour DNA (ctDNA). PLASMA is a prospective, open-label, multicentre single-arm Phase II study. Patients with advanced NSCLC harbouring sensitizing EGFR and T790M mutations in plasma at progression from ≥one 1G/2G TKI were treated with 80 mg of Osimertinib daily until progression. The primary endpoint was the objective response rate (ORR); the secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate (DCR) and toxicities. Plasma next-generation sequencing was performed to determine Osimertinib resistance mechanisms and assess serial ctDNA. A total of 110 patients from eight centres in five countries were enrolled from 2017 to 2019. The median follow-up duration was 2.64 (IQR 2.44-3.12) years. The ORR was 50.9% (95% CI 41.2-60.6) and the DCR was 84.5% (95% CI 76.4-90.7). Median PFS was 7.4 (95% CI 6.0-9.3) months; median OS was 1.63 (95% CI 1.35-2.16) years. Of all of the patients, 76% had treatment-related adverse events (TRAEs), most commonly paronychia (22.7%); 11% experienced ≥ Grade 3 TRAEs. The ctDNA baseline load and dynamics were prognostic. Osimertinib is active in NSCLC harbouring sensitizing EGFR and T790M mutations in ctDNA testing post 1G/2G TKIs.

Evaluation of the Analytical Performance of Oncomine Lung cfDNA Assay for Detection of Plasma EGFR Mutations

BACKGROUND

The clinical utility of circulating tumor DNA (ctDNA) in the early detection of tumor mutations for targeted therapy and the monitoring of tumor recurrence has been reported. However, the analytical validation of ctDNA assays is required for clinical application.

METHODS

This study evaluated the analytical performance of the Oncomine Lung cfDNA Assay compared with the cobas^®EGFR Mutation Test v2. The analytical specificity and sensitivity were estimated using commercially pre-certified reference materials. The comparative evaluation of the two assays was carried out using reference materials and plasma derived from patients diagnosed with lung cancer.

RESULTS

Using 20 ng of input cell-free DNA (cfDNA), the analytical sensitivities for EGFR mutations with variant allele frequencies (VAFs) of 1% and 0.1% were 100% and 100%, respectively. With VAFs of 1.2% and 0.1% using 20 ng of input cfDNA, seven out of nine different mutations in six driver genes were identified in the Oncomine Lung cfDNA Assay. The two assays showed 100% concordance in 16 plasma samples clinically. Furthermore, various PIK3CA and/or TP53 mutations were identified only in the Oncomine Lung cfDNA Assay.

CONCLUSIONS

The Oncomine Lung cfDNA Assay can be used to identify plasma EGFR mutations in patients with lung cancer, although further large-scale studies are required to evaluate the analytical validity for other types of aberrations and genes using clinical samples.

Circulating Tumour DNA (ctDNA) as a Predictor of Clinical Outcome in Non-Small Cell Lung Cancer Undergoing Targeted Therapies: A Systematic Review and Meta-Analysis

BACKGROUND

Liquid biopsy (LB) analysis using (ctDNA)/cell-free DNA (cfDNA) is an emerging alternative to tissue profiling in (NSCLC). LB is used to guide treatment decisions, detect resistance mechanisms, and predicts responses, and, therefore, outcomes. This systematic review and meta-analysis evaluated the impact of LB quantification on clinical outcomes in molecularly altered advanced NSCLC undergoing targeted therapies.

METHODS

We searched Embase, MEDLINE, PubMed, and Cochrane Database, between 1 January 2020 and 31 August 2022. The primary outcome was progression-free survival (PFS). Secondary outcomes included overall survival (OS), objective response rate (ORR), sensitivity, and specificity. Age stratification was performed based on the mean age of the individual study population. The quality of studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

A total of 27 studies (3419 patients) were included in the analysis. Association of baseline ctDNA with PFS was reported in 11 studies (1359 patients), while that of dynamic changes with PFS was reported in 16 studies (1659 patients). Baseline ctDNA-negative patients had a trend towards improved PFS (pooled hazard ratio [pHR] = 1.35; 95%CI: 0.83-1.87; p < 0.001; I² = 96%) than ctDNA-positive patients. Early reduction/clearance of ctDNA levels after treatment was related to improved PFS (pHR = 2.71; 95%CI: 1.85-3.65; I² = 89.4%) compared to those with no reduction/persistence in ctDNA levels. The sensitivity analysis based on study quality (NOS) demonstrated improved PFS only for good [pHR = 1.95; 95%CI: 1.52-2.38] and fair [pHR = 1.99; 95%CI: 1.09-2.89] quality studies, but not for poor quality studies. There was, however, a high level of heterogeneity (I² = 89.4%) along with significant publication bias in our analysis.

CONCLUSIONS

This large systematic review, despite heterogeneity, found that baseline negative ctDNA levels and early reduction in ctDNA following treatment could be strong prognostic markers for PFS and OS in patients undergoing targeted therapies for advanced NSCLC. Future randomised clinical trials should incorporate serial ctDNA monitoring to further establish the clinical utility in advanced NSCLC management.

Treatment of advanced non-small cell lung cancer with driver mutations: current applications and future directions

With the improved understanding of driver mutations in non-small cell lung cancer (NSCLC), expanding the targeted therapeutic options improved the survival and safety. However, responses to these agents are commonly temporary and incomplete. Moreover, even patients with the same oncogenic driver gene can respond diversely to the same agent. Furthermore, the therapeutic role of immune-checkpoint inhibitors (ICIs) in oncogene-driven NSCLC remains unclear. Therefore, this review aimed to classify the management of NSCLC with driver mutations based on the gene subtype, concomitant mutation, and dynamic alternation. Then, we provide an overview of the resistant mechanism of target therapy occurring in targeted alternations ("target-dependent resistance") and in the parallel and downstream pathways ("target-independent resistance"). Thirdly, we discuss the effectiveness of ICIs for NSCLC with driver mutations and the combined therapeutic approaches that might reverse the immunosuppressive tumor immune microenvironment. Finally, we listed the emerging treatment strategies for the new oncogenic alternations, and proposed the perspective of NSCLC with driver mutations. This review will guide clinicians to design tailored treatments for NSCLC with driver mutations.