Clinical utility of plasma-based digital next-generation sequencing in patients with advance-stage lung adenocarcinomas with insufficient tumor samples for tissue genotyping.

BACKGROUND: Approximately 30% of tumor biopsies from patients with advanced-stage lung adenocarcinomas yield insufficient tissue for successful molecular subtyping. We have analyzed the clinical utility of next-generation sequencing (NGS) of cell-free circulating tumor DNA (ctDNA) in patients with inadequate tumor samples for tissue genotyping. PATIENTS AND METHODS: We conducted the study in a multi-institutional prospective cohort of clinically unselected patients with advanced-stage lung adenocarcinomas with insufficient tissue for EGFR, ALK or ROS1 genotyping across 12 Spanish institutions (n = 93). ctDNA NGS was carried out by Guardant Health (Guardant360, Redwood City, CA), using a hybrid-capture-based 73-gene panel. Variants were deemed actionable if they were part of the OncoKB precision oncology knowledge database and classified in four levels of actionability based on their clinical or preclinical evidence for drug response. RESULTS: Eighty-three out of 93 patients (89%) had detectable levels of ctDNA. Potentially actionable level 1-4 genomic alterations were detected in 53 cases (57%), of which 13 (14%) had level 1-2A alterations (Food and Drug Administration-approved and standard-care biomarkers according to lung cancer guidelines). Frequencies of each genomic alteration in ctDNA were consistent with those observed in unselected pulmonary adenocarcinomas. The majority of the patients (62%), particularly those with actionable alterations (87%), had more than one pathogenic variant in ctDNA. The median turnaround time to genomic results was 13 days. Twelve patients (13%) received genotype-matched therapies based on ctDNA results, deriving the expected clinical benefit. Patients with co-occurring pathogenic alterations had a significantly shorter median overall survival as compared with patients without co-occurring pathogenic alteration (multivariate hazard ratio = 5.35, P = 0.01). CONCLUSION: Digital NGS of ctDNA in lung cancers with insufficient tumor samples for tissue sequencing detects actionable variants that frequently co-occur with other potentially clinically relevant genomic alterations, allowing timely initiation of genotype-matched therapies.

Mechanisms of acquired resistance to first- and second-generation EGFR tyrosine kinase inhibitors.

Patients with non-small-cell lung cancer (NSCLC) whose tumours harbour activating mutations within the epidermal growth factor receptor (EGFR) frequently derive significant clinical and radiographic benefits from treatment with EGFR tyrosine kinase inhibitors (TKIs). As such, prospective identification of EGFR mutations is now the standard of care worldwide. However, acquired therapeutic resistance to these agents invariably develops. Over the past 10 years, great strides have been made in defining the molecular mechanisms of EGFR TKI resistance in an effort to design rational strategies to overcome this acquired drug resistance. Approximately 60% of patients with acquired resistance to the EGFR TKIs (erlotinib, gefitinib, and afatinib) develop a new mutation within the drug target. This mutation-T790M-has been shown to alter drug binding and enzymatic activity of the mutant EGF receptor. Less common mechanisms of acquired resistance include MET amplification, ERBB2 amplification, transformation to small-cell lung cancer, and others. Here, we present a condensed overview of the literature on EGFR-mutant NSCLC, paying particular attention to mechanisms of drug resistance, recent clinical trial results, and novel strategies for identifying and confronting drug resistance, while also striving to identify gaps in current knowledge. These advances are rapidly altering the treatment landscape for EGFR-mutant NSCLC, expanding the armamentarium of available therapies to maximize patient benefit.

Erlotinib versus pemetrexed for pretreated non-squamous non-small cell lung cancer patients in clinical practice.

BACKGROUND/AIM: Erlotinib and chemotherapy have shown similar efficacy for pretreated non-small cell lung cancer (NSCLC) patients, but none of the large studies have selected patients based on histology. We present a retrospective single-center series of advanced non-squamous NSCLC patients treated with erlotinib or pemetrexed as second-line therapy. Our aim was to compare the efficacy and safety data under clinical practice conditions and to identify subgroups of patients who could benefit more from these therapies. METHODS: A total of 88 patients were included. Squamous histology was our main exclusion criterion. EGFR mutation status was known for 54.5% of the patients; 6 patients treated with erlotinib and 2 with pemetrexed had EGFR-mutated tumors. Smoking history was analyzed as possible predictive factor of efficacy. RESULTS: No significant differences in progression-free survival (PFS; 3 vs. 2.5 months, p = 0.06) or overall survival (OS; 4.9 vs. 7.4 months, p = 0.733) between the erlotinib and pemetrexed groups were found in the overall population. EGFR wild-type patients had a similar median PFS with erlotinib compared to pemetrexed (2.7 vs. 2.3 months, p = 0.42), with no statistical differences in OS. Statistically significant differences in OS in favor of pemetrexed for current smokers (3 vs. 7.1 months, p = 0.017) were found, while erlotinib achieved significantly better PFS in never-smokers compared to former smokers (3.5 vs. 2.7 months, p = 0.005). Serious adverse events were uncommon but more frequent with pemetrexed, and were mainly related to hematologic toxicity. CONCLUSIONS: Erlotinib should be considered as another equal option in second-line treatment for EGFR wild-type patients as well as for subpopulations with unknown mutational status. Smoking history could be a useful clinical marker to choose a second-line treatment.

Analysis of expression of PTEN/PI3K pathway and programmed cell death ligand 1 (PD-L1) in malignant pleural mesothelioma (MPM).

BACKGROUND: Malignant pleural mesothelioma (MPM) frequently express elevated AKT/mTOR activity. Previous reports in gliomas, colon, breast and prostate cancer suggest that PTEN/PI3K pathway may be important for the induction of PD-L1 expression. This study explored the expression of PTEN/PI3K pathway and PD-L1 in MPM and its relationship with the patient́s prognosis MATERIAL AND METHODS: Twenty seven consecutive MPM patients were reviewed. Formalin-fixed, paraffin-embedded tissue biopsies were used for immunohistochemical analysis of PTEN/PI3K pathway and PD-L1 RESULTS: Expression of PTEN, mTOR, pAKT, p4EBP1, peif4E, pS6 and FOXO3a was found in 88.5%, 92.3%, 78.3%, 38.5%, 100%, 52.2% and 100% of tumors and PD-L1 in 23%. We found a significant correlation between pAKT, FOXO3a and PD-L1 expression and longer overall survival (p <0.05). We did not identify significant association between the level of PD-L1 expression and alterations in PI3K pathway CONCLUSIONS: This study shows PTEN/PI3K pathway and PD-L1 in MPM are frequently activated. Our results suggests that there is not association between PD-L1 and the involvement of the PI3K pathway in MPM.