Concordance analysis between liquid biopsy (ctDNA) and tumor DNA molecular profiles from panel-based next-generation sequencing.

INTRODUCTION: Analysis of circulating tumor DNA (ctDNA), also known as liquid biopsy, has been postulated to be a useful test in the prognostication, molecular profiling, and monitoring of cancer patients. In this series we aimed to analyze the concordance between the mutation status of formalin-fixed paraffin-embedded (FFPE) tumor samples and matched ctDNA, considering tumor molecular profiling as the gold standard technique. METHODS: This retrospective study included cancer patients with complete diagnostics and gene mutations detected in a previous FFPE tumor tissue Next-Generation Sequencing (NGS) study with a matched frozen plasma sample available for an NGS ctDNA assay. RESULTS AND DISCUSSION: Sixty patients were included, 24 with colorectal carcinoma (CRC) and 36 with non-small cell lung cancer (NSCLC). In 27.1% of ctDNA studies a new mutation not previously detected in the matched tumor was found. 11.9% of these ctDNA results had the potential to impact clinical management. Globally, the concordance rate between FFPE tumor samples and ctDNA was 44.4%. When tumors were stratified by stage, the concordance was 76.5%, 70%, 36.4%, and 0% in tumor stages IV, III, II, and I, respectively. ctDNA molecular profiles showed a good concordance rate in advanced stage tumors and identified undetected mutations in tumor tissues. In early tumor stages the concordance was low, casting doubt on the usefulness of ctDNA in these patients.

Concordance analysis between liquid biopsy (ctDNA) and tumor DNA molecular profiles from panel-based next-generation sequencing

Introduction: Analysis of circulating tumor DNA (ctDNA), also known as liquid biopsy, has been postulated to be a useful test in the prognostication, molecular profiling, and monitoring of cancer patients. In this series we aimed to analyze the concordance between the mutation status of formalin-fixed paraffin-embedded (FFPE) tumor samples and matched ctDNA, considering tumor molecular profiling as the gold standard technique. Methods: This retrospective study included cancer patients with complete diagnostics and gene mutations detected in a previous FFPE tumor tissue Next-Generation Sequencing (NGS) study with a matched frozen plasma sample available for an NGS ctDNA assay. Results and discussion: Sixty patients were included, 24 with colorectal carcinoma (CRC) and 36 with non-small cell lung cancer (NSCLC). In 27.1% of ctDNA studies a new mutation not previously detected in the matched tumor was found. 11.9% of these ctDNA results had the potential to impact clinical management. Globally, the concordance rate between FFPE tumor samples and ctDNA was 44.4%. When tumors were stratified by stage, the concordance was 76.5%, 70%, 36.4%, and 0% in tumor stages IV, III, II, and I, respectively. ctDNA molecular profiles showed a good concordance rate in advanced stage tumors and identified undetected mutations in tumor tissues. In early tumor stages the concordance was low, casting doubt on the usefulness of ctDNA in these patients.(AU)

Introducción: Se ha postulado que el análisis de ADN tumoral circulante (ctDNA), conocido también como biopsia líquida, es una prueba útil a la hora de pronosticar, elaborar el perfilado molecular, y supervisar a los pacientes de cáncer. En esta serie nuestro objetivo fue analizar la concordancia entre el estatus mutacional de las muestras tumorales (formalin-fixed paraffin-embedded) y el ctDNA equiparado, considerando el perfilado molecular del tumor la técnica de referencia. Métodos: Este estudio retrospectivo incluyó pacientes de cáncer con diagnóstico completo y mutaciones genéticas detectadas en un estudio anterior de NGS de tejido tumoral formalin-fixed paraffin-embedded con una muestra equiparada de plasma congelado disponible para un ensayo ctDNA mediante NGS. Resultados y discusión: Incluimos sesenta pacientes: 24 con cáncer colorrectal y 36 con cáncer de pulmón de células no pequeñas (NSCLC). En el 27,1% de los estudios de ctDNA se encontró una nueva mutación no detectada previamente en el tumor equiparado. El 11,9% de dichos resultados de ctDNA tenía potencial de repercutir en el manejo clínico. A nivel global, la tasa de concordancia entre las muestras tumorales formalin-fixed paraffin-embedded y ctDNA fue del 44,4%. Al estratificar los tumores por estadio, la concordancia fue del 76,5%, 70%, 36,4%, y 0% para los estadios tumorales IV, III, II, y I, respectivamente. Los perfiles moleculares de ctDNA reflejaron una buena tasa de concordancia en tumores de estadio avanzado, e identificaron mutaciones no detectadas en los tejidos tumorales. En los estadios tumorales tempranos la concordancia fue baja, planteando dudas sobre la utilidad de ctDNA en dichos pacientes.(AU)

Plasmatic KRAS Kinetics for the Prediction of Treatment Response and Progression in Patients With KRAS-mutant Lung Adenocarcinoma / Estudio de la cinética del KRAS plasmático para predecir la respuesta al tratamiento y la progresión en pacientes con adenocarcinoma de pulmón con mutación de KRAS

Introduction: KRAS is the most common driver mutation in lung cancer. ctDNA-based assessment offers advantages over tumor as a minimally invasive method able to capture tumor heterogeneity. Monitoring KRAS mutational load in ctDNA may be useful in the management of the patients.Methods: Consecutive patients diagnosed with KRAS mutant lung adenocarcinoma in the tumor biopsy were included in this study. Plasma samples were obtained at different time points during the course of the disease. KRAS mutations in plasma were quantified using digital PCR and correlated with mutations in tumor and with radiological response and progression.Results: Two hundred and forty-five plasma samples from 56 patients were analyzed. The rate of detection of KRAS mutations in plasma in our previously characterized KRAS-mutant cases was 82% overall, reaching 96% in cases with more than 1 metastatic location. The dynamics of KRAS mutational load predicted response in 93% and progression in 63% of cases, 33 and 50 days respectively in advance of radiological evaluation. Progression-free survival for patients in whom ctDNA was not detectable in plasma after treatment initiation was significantly longer than for those in whom ctDNA remained detectable (7.7 versus 3.2 months; HR: 0.44, p=0.004).Conclusions: The detection of KRAS mutations in ctDNA showed a good correlation with that in tumor biopsy and, in most cases, predicted tumor response and progression to chemotherapy in advance of radiographic evaluation. The liquid biopsies for ctDNA-based molecular analyses are a reliable tool for KRAS testing in clinical practice. (AU)

Introducción: La mutación en KRAS es la mutación iniciadora más común en el cáncer de pulmón. La valoración basada en el ctDNA ofrece ventajas frente a la tumoral, al ser un método mínimamente invasivo capaz de capturar la heterogeneidad del tumor. La monitorización de la carga de KRAS mutado en el ctDNA puede ser útil en el manejo de los pacientes.Métodos: En este estudio se incluyó, mediante selección consecutiva, a pacientes diagnosticados con adenocarcinoma de pulmón con mutación en KRAS en la biopsia tumoral. Se obtuvieron muestras de plasma en diferentes momentos durante el curso de la enfermedad. Las mutaciones de KRAS en plasma se cuantificaron mediante PCR digital y se correlacionaron con las mutaciones en el tumor y con la respuesta radiológica y la progresión.Resultados: Se analizaron 245 muestras de plasma de 56 pacientes. La tasa de detección de mutaciones KRAS en plasma en aquellos casos previamente definidos con dicha mutación fue del 82% globalmente, porcentaje que alcanzó el 96% en aquellos casos con más de una ubicación metastásica. La dinámica de la carga de KRAS mutado predijo la respuesta en el 93% de los casos y la progresión en el 63%, a los 33 y 50 días, respectivamente, anteriores a la evaluación radiológica. La supervivencia libre de progresión para pacientes en los que el ctDNA no era detectable en plasma después del inicio del tratamiento fue significativamente más larga que para aquellos en los que el ctDNA permaneció detectable (7,7 frente a 3,2 meses; HR: 0,44; p = 0,004).Conclusiones: La detección de mutaciones KRAS en el ctDNA mostró una buena correlación con la de la biopsia tumoral y, en la mayoría de los casos, predijo la respuesta tumoral a la quimioterapia y la progresión antes de la evaluación radiológica. Las biopsias líquidas para análisis moleculares basados en ctDNA son una herramienta fiable para la valoración de KRAS en la práctica clínica. (AU)

Plasmatic KRAS Kinetics for the Prediction of Treatment Response and Progression in Patients With KRAS-mutant Lung Adenocarcinoma.

INTRODUCTION: KRAS is the most common driver mutation in lung cancer. ctDNA-based assessment offers advantages over tumor as a minimally invasive method able to capture tumor heterogeneity. Monitoring KRAS mutational load in ctDNA may be useful in the management of the patients. METHODS: Consecutive patients diagnosed with KRAS mutant lung adenocarcinoma in the tumor biopsy were included in this study. Plasma samples were obtained at different time points during the course of the disease. KRAS mutations in plasma were quantified using digital PCR and correlated with mutations in tumor and with radiological response and progression. RESULTS: Two hundred and forty-five plasma samples from 56 patients were analyzed. The rate of detection of KRAS mutations in plasma in our previously characterized KRAS-mutant cases was 82% overall, reaching 96% in cases with more than 1 metastatic location. The dynamics of KRAS mutational load predicted response in 93% and progression in 63% of cases, 33 and 50 days respectively in advance of radiological evaluation. Progression-free survival for patients in whom ctDNA was not detectable in plasma after treatment initiation was significantly longer than for those in whom ctDNA remained detectable (7.7 versus 3.2 months; HR: 0.44, p=0.004). CONCLUSIONS: The detection of KRAS mutations in ctDNA showed a good correlation with that in tumor biopsy and, in most cases, predicted tumor response and progression to chemotherapy in advance of radiographic evaluation. The liquid biopsies for ctDNA-based molecular analyses are a reliable tool for KRAS testing in clinical practice.

Liquid biopsy and prostate cancer. Current evidence applied to clinical practice. / Biopsia líquida y cáncer de próstata. Evidencia actual aplicada a la clínica.

CONTEXT: Despite being a validated source of biomarkers, liquid biopsy has not yet succeeded in becoming part of the standard clinical practice in prostate cancer patients. Few biomarkers undergo adequate validation, prospective and independent, of their predictive and/or prognostic value, which results in a lack of the different available tests in the clinical practice. OBJECTIVE: To carry out a pragmatic synthesis of current scientific evidence on liquid biopsy for prostate cancer patients. EVIDENCE ACQUISITION: Non-systematic literature review, narrowing the search to papers on liquid biopsy from blood samples in prostate cancer patients. We mainly selected works evaluating clinical endpoints in prostate cancer. EVIDENCE SYNTHESIS: The most clinically advanced forms of liquid biopsy are circulating tumor cells (CTCs) and circulating tumor DNA (ctDNA). Both CTCs and ctDNA have demonstrated their prognostic value in metastatic disease. ARV7 determination is the first predictive biomarker of the disease. Its implementation into routine clinical practice requires methodological standardization and adequate clinical validation of the different available ways to detect it. The detection of CTCs in the early stages of the disease still depends on the optimization of the diagnostic methods and on the development of the biological characterization of these cells. The biological information provided by CTCs and ctDNA is different; therefore, the study of its adequate combination is the object of cutting-edge research. CONCLUSIONS: The absence of protocols and methodological standards is the limiting factor when aiming to reach conclusions that could have a potential impact on clinical practice. Therefore, the real short-term challenge for liquid biopsy is the establishment of consensus and common criteria.