Update on molecular pathology and role of liquid biopsy in nonsmall cell lung cancer

Clinical utility and predictive value of cerebrospinal fluid cell-free DNA profiling in non-small cell lung cancer patients with leptomeningeal metastasis

Leptomeningeal metastasis (LM) is a challenging complication of non-small cell lung cancer (NSCLC). Cerebrospinal fluid (CSF) cell-free DNA (cfDNA) analysis using next-generation sequencing (NGS) offers insights into resistance mechanisms and potential treatment strategies. We conducted a study from February 2022 to April 2023 involving patients from five hospitals in Taiwan who had recurrent or advanced NSCLC with LM. These patients underwent CSF cfDNA analysis using a 118-gene targeted panel for NGS, with comprehensive clinical data collected. Among 25 enrolled patients, 22 (88.0 %) had EGFR mutations, while three (12.0 %) had EML4-ALK fusion, KIF5B-RET fusion, and ERBB2 A775_G776insSVMA. CSF cfDNA sequencing of 27 samples (from 25 patients) all confirmed their original driver mutations. Of total cohort, 18 patients (72.0 %) underwent intrathecal pemetrexed (ITP), with a median survival time of 7.4 months (95.0 % confidence interval, 3.3-11.6) from the initiation of ITP to death. Among them, ten individuals (55.6 %) survived beyond 6 months. Notably, MET copy number gain (CNG) correlated significantly with survival time exceeding 6 months after ITP (p = 0.007). The coexistence of EGFR T790M and EGFR-independent resistance alterations was associated with shorter survival times after ITP, with a median survival time of 1.9 months compared to 9.9 months for those without EGFR T790M (p = 0.010). Our results highlight CSF cfDNA NGS's potential in LM resistance understanding and ITP efficacy prediction. MET CNG positively impacts survival for ITP recipients, whereas the coexistence of EGFR T790M and EGFR-independent resistance mechanisms leads to poor outcomes.

Transbronchial lung cryobiopsy for peripheral pulmonary lesions. A narrative review

An increasing number of peripheral pulmonary lesions (PPLs) requiring tissue verification to establish a definite diagnosis for further individualized management are detected due to the growing adoption of lung cancer screening by chest computed tomography (CT), especially low-dose CT. However, the morphological diagnosis of PPLs remains challenging. Transbronchial lung cryobiopsy (TBLC) that can retrieve larger specimens with more preserved cellular architecture and fewer crush artifacts in comparison with conventional transbronchial forceps biopsy (TBFB), as an emerging technology for diagnosing PPLs, has been demonstrated to have the potential to resolve the clinical dilemma pertaining to currently available sampling devices (e.g., forceps, needle and brush) and become a diagnostic cornerstone for PPLs. Of note, with the introduction of the 1.1 mm cryoprobe that will be more compatible with advanced bronchoscopic navigation techniques, such as radial endobronchial ultrasound (r-EBUS), virtual bronchoscopic navigation (VBN) and electromagnetic navigation bronchoscopy (ENB), the use of TBLC is expected to gain more popularity in the diagnosis of PPLs. While much remains for exploration using the TBLC technique for diagnosing PPLs, it can be envisaged that the emergence of additional studies with larger data accrual will hopefully add to the body of evidence in this field.

Practical challenges in lung cancer pathology: bedside care to treatment decisions

PURPOSE OF REVIEW

Lung cancer is one of the most common malignancies in the whole world, and the pulmonologist is generally the first medical professional to meet the patient and decide what method of tumour sampling is preferable in each specific case. It is imperative for pulmonary physicians to be aware of the intricacies of the diagnostic process, and understand the multiple challenges that are encountered, from the moment the tissue specimen leaves their offices and is sent to the pathology laboratory, until the diagnosis reaches the patient and treating physician.

RECENT FINDINGS

The new 2021 WHO classification of thoracic tumours recommended a minimum immunohistochemical (IHC) diagnostic panel for nonsmall cell lung cancer (NSCLC), and following publications of different institutional and country-based guidelines, advocated basic molecular testing for epithelial growth factor receptor (EGFR), anaplastic lymphoma kinase (ALK) and programmed cell death ligand 1 (PD-L1) to be initiated by the diagnosing pathologist in all cases of biopsy or resection specimens. In general, sequential testing for molecular biomarkers was not recommended due to tissue wastage, instead next generation sequencing (NGS) diagnostic panel was supported.

SUMMARY

The lung cancer specimen has to undergo histologic diagnosis through a panel of IHC studies, and -preferably, a reflex molecular study by NGS including several targetable genes. Adequate communication and clinical information preclude the pathologist from "overusing" the tissue for additional studies, while focusing on preservation of material for molecular testing.

Therapeutic strategies for BRAF mutation in non-small cell lung cancer: a review

Lung cancer is the leading cause of cancer related deaths. Among the two broad types of lung cancer, non-small cell lung cancer accounts for 85% of the cases. The study of the genetic alteration has facilitated the development of targeted therapeutic interventions. Some of the molecular alterations which are important targets for drug therapy include Kirsten rat sarcoma (KRAS), Epidermal Growth Factor Receptor (EGFR), V-RAF murine sarcoma viral oncogene homolog B (BRAF), anaplastic lymphoma kinase gene (ALK). In the setting of extensive on-going clinical trials, it is imperative to periodically review the advancements and the newer drug therapies being available. Among all mutations, BRAF mutation is common with incidence being 8% overall and 1.5 - 4% in NSCLC. Here, we have summarized the BRAF mutation types and reviewed the various drug therapy available - for both V600 and nonV600 group; the mechanism of resistance to BRAF inhibitors and strategies to overcome it; the significance of comprehensive profiling of concurrent mutations, and the role of immune checkpoint inhibitor in BRAF mutated NSCLC. We have also included the currently ongoing clinical trials and recent advancements including combination therapy that would play a role in improving the overall survival and outcome of NSCLC.

Liquid Biopsies in Lung Cancer

As lung cancer has the highest cancer-specific mortality rates worldwide, there is an urgent need for new therapeutic and diagnostic approaches to detect early-stage tumors and to monitor their response to the therapy. In addition to the well-established tissue biopsy analysis, liquid-biopsy-based assays may evolve as an important diagnostic tool. The analysis of circulating tumor DNA (ctDNA) is the most established method, followed by other methods such as the analysis of circulating tumor cells (CTCs), microRNAs (miRNAs), and extracellular vesicles (EVs). Both PCR- and NGS-based assays are used for the mutational assessment of lung cancer, including the most frequent driver mutations. However, ctDNA analysis might also play a role in monitoring the efficacy of immunotherapy and its recent accomplishments in the landscape of state-of-the-art lung cancer therapy. Despite the promising aspects of liquid-biopsy-based assays, there are some limitations regarding their sensitivity (risk of false-negative results) and specificity (interpretation of false-positive results). Hence, further studies are needed to evaluate the usefulness of liquid biopsies for lung cancer. Liquid-biopsy-based assays might be integrated into the diagnostic guidelines for lung cancer as a tool to complement conventional tissue sampling.

Evaluation of the cell-free DNA integrity index as a liquid biopsy marker to differentiate hepatocellular carcinoma from chronic liver disease

Background: Hepatocellular carcinoma (HCC) occurs in the majority of patients with underlying chronic liver disease (CLD) of viral and non-viral etiologies, which requires screening for early HCC diagnosis. Liquid biopsy holds great promise now for early detection, prognosis, and assessment of response to cancer therapy. Cell-free DNA (cfDNA) as a liquid biopsy marker can be easily detected by a real-time quantitative PCR (RT-qPCR) assay for a change in its concentration, integrity, and fragmentation in cancer. Methods: Patients with HCC (n = 100), CLD (n = 100), and healthy (n = 30) controls were included in the study. The cfDNA was isolated from serum and real-time quantitative PCR (RT-qPCR) was carried out using primer pairs for large (>205 bp) and small (110 bp) fragments of repetitive elements (ALU and LINE1) and housekeeping genes (β-Actin and GAPDH). Total cfDNA concentrations and integrity index were determined by the absolute quantitation method (L/S ratio or cfDII-integrity). The cfDII as a measure of fragmentation was determined by comparative Ct (2-ΔΔCt) method of relative quantification (cfDII-fragmentation). Using a receiver operating characteristic (ROC) curve, cfDII-integrity and cfDII-fragmentation were used to differentiate HCC from CLD patients or healthy controls. Results: The total cfDNA concentrations in the sera of HCC (244 ng/ml) patients were significantly higher than those of CLD (33 ng/ml) patients and healthy (16.88 ng/ml) controls. HCC patients have shown poor DNA integrity or excess cfDNA fragmentation than CLD patients and healthy controls. The cfDII-integrity of GAPDH and ALU fragment significantly differentiate HCC from CLD at AUROC 0.72 and 0.67, respectively. The cfDII-fragmentation following normalization with cfDNA of healthy control has shown significant differential capabilities of HCC from CLD at AUROC 0.67 using GAPDH and 0.68 using the ALU element. The ROC curve of LINE1 and β-actin cfDII was not found significant for any of the above methods. The cfDII-fragmentation trend in HCC patients of different etiologies was similar indicating increased cfDNA fragmentation irrespective of its etiology. Conclusion: The cfDII measuring both DNA integrity (L/S ratio) and fragmentation of the Alu and GAPDH genes can differentiate HCC from CLD patients and healthy individuals.

Osimertinib: A Review in Completely Resected, Early-Stage, EGFR Mutation-Positive NSCLC

Osimertinib (TAGRISSO^®) is an orally administered, third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that is approved for the adjuvant treatment of adults with completely resected, stage IB-IIIA, EGFR sensitizing mutation (exon 19 deletion or exon 21 [L858R] substitution)-positive non-small cell lung cancer (NSCLC). In the pivotal ADAURA trial in adults with completely resected, early-stage, EGFR mutation-positive (EGFRm+) NSCLC, osimertinib adjuvant therapy significantly prolonged disease-free survival (DFS) compared with placebo in the overall population of patients with stage IB-IIIA disease, as well as in the primary population of patients with stage II-IIIA disease. A DFS benefit of osimertinib was seen irrespective of whether or not patients received prior adjuvant chemotherapy. Overall survival (OS) data were very immature at the time of the analysis of DFS, and more mature OS data are awaited with interest. Osimertinib adjuvant therapy did not adversely affect health-related quality of life and was generally well tolerated, with a manageable safety profile and no new safety signals identified. Based on the available evidence, osimertinib is thus an appropriate targeted option for the adjuvant treatment of adults with completely resected, stage IB-IIIA, EGFRm+ NSCLC.