Plasma pre-treatment T790M relative allelic frequency in patients with advanced EGFR-mutated non-small cell lung cancer predicts treatment response to subsequent-line osimertinib

Utility of multigene panel next-generation sequencing in routine clinical practice for identifying genomic alterations in newly diagnosed metastatic nonsmall cell lung cancer

BACKGROUND

The standard of care in newly diagnosed metastatic non-small cell lung cancer (NSCLC) is to test for aberrations in three genes for driver mutations - ALK, ROS1 and epidermal growth factor receptor (EGFR) - and also for immunohistochemistry to be performed for programmed death-ligand 1 expression level. Next-generation sequencing (NGS), with or without RNA fusion testing, is increasingly used in standard clinical practice to identify patients with potentially actionable mutations. Stratification of NGS mutation tiers is currently based on the European Society of Medical Oncology Scale for Clinical Actionability of Molecular Targets (ESCAT) Tiers I-V and X.

AIM

Our aim was to analyse NSCLC tumour samples for the prevalence of Tiers I-V mutations to establish guidance for current and novel treatments in patients with metastatic disease.

METHODS

NGS was performed employing the Oncomine Precision Assay (without RNA fusion testing) that interrogates DNA hotspot variants across 45 genes to screen 210 NSCLC tissue samples obtained across six Sydney hospitals between June 2021 and March 2022.

RESULTS

In our cohort, 161 of 210 (77%) had at least one gene mutation identified, with 41 of 210 (20%) having two or more concurrent mutations. Tier I mutations included 42 of 210 (20%) EGFR mutations (EIA) and five of 210 (3%) MET exon 14 skipping mutations (EIB). Non-Tier I variants included 22 of 210 (11%) KRAS G12C hotspot mutations (EIIB), with a further 47 of 210 (22%) having non-G12C KRAS (EX) mutations. NGS testing revealed an additional 15% of cases with Tier II ESCAT mutations in NSCLC. Forty-six percent of patients also demonstrated potential Tier III and IV mutations that are currently under investigation in early-phase clinical trials.

CONCLUSIONS

In addition to identifying patients with genomic alterations suitable for clinically proven standard-of-care therapeutic options, the 45-gene NGS panel has significant potential in identifying potentially actionable non-Tier 1 mutations that may become future standard clinical practice in NSCLC.

Predictive significance of circulating tumor DNA against patients with T790M-positive EGFR-mutant NSCLC receiving osimertinib

Circulating tumor DNA (ctDNA) provides molecular information on tumor heterogeneity. The prognostic usefulness of ctDNA after first-line epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are limited. Therefore, the present study evaluated ctDNA during osimertinib administration as a second-line or more setting to identify the relationship between EGFR mutation levels and outcomes in patients with advanced non-small cell lung cancer (NSCLC). Forty patients with EGFR T790M-positive NSCLC receiving osimertinib after prior EGFR-TKI treatment were registered. Plasma samples were collected at osimertinib pretreatment, after 1 month of treatment, and at the time of progressive disease (PD). ctDNA analysis was performed by digital polymerase chain reaction. The detection rate of copy numbers of exon 19 deletion, L858R, and T790M in plasma samples was significantly lower 1 month after osimertinib than at pretreatment, and significantly higher at PD than at 1 month, whereas that of C797S was significantly higher at PD than at 1 month. No statistically significant difference was observed in the copy numbers of exon 19 deletion, L858R, T790M, and C797S between complete response or partial response and stable disease or PD. The detection of T790M at PD after osimertinib initiation was a significant independent prognostic factor for predicting shorter prognosis, and the presence of major EGFR mutations at pretreatment and PD was closely linked to worse survival after osimertinib initiation. Molecular testing based on ctDNA is helpful for predicting outcomes of osimertinib treatment in T790M-positive NSCLC after previous EGFR-TKI treatment.

BRAF V600E-mutated large cell neuroendocrine carcinoma responding to targeted therapy: a case report and review of the literature

Large cell neuroendocrine carcinoma (LCNEC) is a rare and aggressive high-grade neuroendocrine tumor, commonly arising in the lung or in the gastrointestinal tract, with a frequent proportion of unknown primary origin (20%). In the metastatic setting, platinum-based or fluoropyrimidine-based chemotherapeutic regimens are as considered the first-line treatment, despite the limited duration of response. To date, the prognosis of advanced high-grade neuroendocrine carcinoma remains poor, suggesting the need to explore new treatment strategies in this orphan tumor. The evolving molecular landscape of LCNEC, not yet been completely defined, could explain the heterogeneous response to different chemotherapeutic regimens and suggest that treatment strategy could be driven by molecular features. v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutations, well described in melanoma, thyroid cancer, colon cancer and lung adenocarcinoma, account for approximately 2% of cases in lung LCNEC. Here, we describe the case of a patient with a BRAF V600E-mutated LCNEC of unknown primary origin who partially responded to BRAF/mitogen-activated protein kinase kinase inhibitors after standard treatment. Additionally, BRAF V600E circulating tumor DNA was used to monitor disease response. Thereafter, we reviewed the available literature about the role of targeted therapy in high-grade neuroendocrine neoplasms to provide insight for future research to identify patients with driver oncogenic mutations, who can potentially benefit from target therapy.

Multigene panel next generation sequencing in metastatic colorectal cancer in an Australian population

BACKGROUND

Next generation sequencing (NGS) is increasingly used in standard clinical practice to identify patients with potentially actionable mutations. Stratification of NGS mutation tiers is currently based on the European Society of Medical Oncology (ESMO) Scale for Clinical Actionability of Molecular Targets (ESCAT[E]) Tier I-V & X. Allele frequency is also increasingly recognised as an important prognostic tool in advanced cancer. The aim of this study was to determine the genomic mutations in metastatic colorectal cancer (CRC) in an Australian multicultural population and their influence on survival outcomes.

METHODS

Next generation sequencing with the 50-gene panel Oncomine Precision Assay™ was used on 180 CRC tissue samples obtained across six Sydney hospitals between June 2021 and March 2022.

RESULTS

From 180 samples, 147 (82%) had at least one gene mutation identified with 68 (38%) having two or more concurrent mutations. Tier I variants included RAS wild-type [EI] in 73 (41%) and BRAF V600E [EIA] in 27 (15%). Non-tier I variants include 2 (1%) ERBB2 amplification [EIIB], 26 (15%) PIK3CA hotspot mutations [EIIIA] and 9 (5%) MET focal amplifications [EIIIA]. NGS testing revealed an additional 22% of cases with Tier II & III mutations. 43% of patients also presented with potentially actionable Tier III & IV mutations. Patients with concurrent TP53 and RAS mutations had significantly reduced overall survival (6.1 months versus 21.1 months, p <0.01). High KRAS allele frequency, as defined by those with over 20% variant allele frequency (VAF), also demonstrated reduced overall survival (12.1 months versus 42.9 months, p = 0.04).

CONCLUSIONS

In addition to identifying patients with genomic alterations suitable for clinically proven standard of care therapeutic options, the 50 gene NGS panel has significant potential in identifying potentially actionable non-tier 1 mutations and therefore may become future standard clinical practice.

Liquid biopsy and non-small cell lung cancer: are we looking at the tip of the iceberg?

The possibility to analyse the tumour genetic material shed in the blood is undoubtedly one of the main achievements of translational research in the latest years. In the modern clinical management of advanced non-small cell lung cancer, molecular characterisation plays an essential role. In parallel, immunotherapy is widely employed, but reliable predictive markers are not available yet. Liquid biopsy has the potential to face the two issues and to increase its role in advanced NSCLC in the next future. The aim of this review is to summarise the main clinical applications of liquid biopsy in advanced non-small cell lung cancer, underlining both its potential and limitations from a clinically driven perspective.