Critical Assessment in Routine Clinical Practice of Liquid Biopsy for EGFR Status Testing in Non-Small-Cell Lung Cancer: A Single-Laboratory Experience (LPCE, Nice, France).

BACKGROUND: The introduction of liquid biopsy using PCR-based assays into routine practice has had a strong impact on the treatment of EGFR-mutated lung adenocarcinoma and is now commonly used for routine testing of EGFR mutations in certain clinical settings. To assess whether the claimed benefits of PCR-based assays hold true in daily practice at a multicenter clinical institution, we assessed how treatment decisions are affected by PCR-based assays for the analysis of EGFR mutations from plasma samples in a centralized laboratory (LPCE, Nice, France). PATIENTS AND METHODS: A total of 345 samples were analyzed using the US Food and Drug Administration-approved Cobas EGFR Mutation Test v2 and 103 using the Therascreen EGFR Plasma RGQ PCR Kit over 3 years (395 samples from 324 patients). Eleven plasma samples were validated independently using Cobas at 3 institutions, and 130 samples were analyzed using Stilla digital PCR. Clinical data were collected for 175 (54%) of 324 patients. RESULTS: Cobas was superior to the Therascreen assay and demonstrated 100% reproducibility. Digital PCR showed only 48%, 83%, and 58% concordance with Cobas for exon 19 deletions, L858R mutations, and T790M mutations, respectively. Liquid biopsies helped inform and change treatment when resistance occurred and enabled the detection of EGFR mutations in patients when biopsy tissue results were unavailable. CONCLUSION: PCR-based assays are a fast and convenient test, allowing the detection of primary and secondary EGFR mutations from plasma. Cobas proved to be a reliable test, whereas digital PCR produced too many inconclusive results to be currently recommended as a principal testing device.

Effect of mutant variants of the KRAS gene on PD-L1 expression and on the immune microenvironment and association with clinical outcome in lung adenocarcinoma patients.

OBJECTIVES: The effect of anti-PD-1/PD-L1 inhibitors on lung adenocarcinomas (LADCs) with KRAS mutations is debatable. We examined the association between specific mutant KRAS proteins and the immune infiltrates with the outcome of patients with LADCs. PATIENTS AND METHODS: In 219 LADCs harboring either wild-type (WT) or mutated KRAS gene, we quantified the density of several immune markers by immunohistochemistry followed by automated digital image analysis. Data were correlated to clinicopathological parameters and outcome of patients. RESULTS: Tumors harboring mutant KRAS-G12 V had a significantly higher PD-L1 expression compared to other tumors (p = 0.044), while mutant KRAS-G12D tumors showed an increase in the density of CD66b+ cells (p = 0.001). High PD-L1 expression in tumor cells was associated to improved overall survival (OS) in KRAS mutant patients (p = 0.012), but not in the WT population (p = 0.385), whereas increased PD-L1 expression in immune cells correlated to poor OS of KRAS-WT patients (p = 0.025), with no difference in patients with KRAS mutations. CONCLUSIONS: KRAS mutational status can affect the immune microenvironment and survival of LADC patients in a heterogeneous way, implying that specific mutant KRAS variants expressed by the tumor should be considered when stratifying patients for immunotherapy.

Ensuring the Safety and Security of Frozen Lung Cancer Tissue Collections through the Encapsulation of Dried DNA.

Collected specimens for research purposes may or may not be made available depending on their scarcity and/or on the project needs. Their protection against degradation or in the event of an incident is pivotal. Duplication and storage on a different site is the best way to assure their sustainability. The conservation of samples at room temperature (RT) by duplication can facilitate their protection. We describe a security system for the collection of non-small cell lung cancers (NSCLC) stored in the biobank of the Nice Hospital Center, France, by duplication and conservation of lyophilized (dried), encapsulated DNA kept at RT. Therefore, three frozen tissue collections from non-smoking, early stage and sarcomatoid carcinoma NSCLC patients were selected for this study. DNA was extracted, lyophilized and encapsulated at RT under anoxic conditions using the DNAshell technology. In total, 1974 samples from 987 patients were encapsulated. Six and two capsules from each sample were stored in the biobanks of the Nice and Grenoble (France) Hospitals, respectively. In conclusion, DNA maintained at RT allows for the conservation, duplication and durability of collections of interest stored in biobanks. This is a low-cost and safe technology that requires a limited amount of space and has a low environmental impact.