Clinical Validity of Tumor-Informed Circulating Tumor DNA Analysis in Patients Undergoing Surgery of Colorectal Metastases

Abstract

Background: Accurate biomarkers to monitor tumor load and response in metastatic colorectal cancer patients undergoing surgery could optimize treatment regimens.

Objective: This study aimed to explore the clinical validity of tumor-informed quantification of circulating tumor DNA in blood using ultradeep sequencing.

Design: Resection specimens from 53 colorectal cancer patients were analyzed for tumor-specific mutations in 15 genes. These mutations were used to measure the presence of circulating tumor DNA in preoperatively collected plasma samples using hybrid capture-based sequencing. Additional postoperative measurements were performed 1 week after surgery in 16 patients.

Settings: The study was conducted at the Radboud University Medical Center.

Patients: A total of 53 colorectal cancer patients undergoing surgery of metastases were included.

Main outcome measures: The detection of circulating tumor DNA.

Results: At least 1 tumor-specific mutation was detected in all tumor samples. In preoperative plasma samples, circulating tumor DNA was detected in 88% (37/42) of systemic treatment-naïve patients and in 55% (6/11) of patients who received preoperative chemotherapy. More specifically, circulating tumor DNA was detected in 0% (0/3) of cases with a subtotal or partial pathologic response and in 75% (6/8) of cases without a pathologic response in the resection specimen ( p = 0.06). In postoperative plasma samples, circulating tumor DNA was detected in 80% (4/5) of patients with an incomplete resection and in 0% (0/11) of those with a complete resection ( p = 0.003).

Limitations: The study was limited by the heterogeneity of the cohort and the small number of postoperative plasma samples.

Conclusions: These data indicate that tumor-informed circulating tumor DNA detection in the plasma of patients undergoing surgery for metastatic colorectal cancer is feasible and may have clinical value in response monitoring and predicting residual disease. Prospective studies are needed to establish the clinical utility of circulating tumor DNA analysis to guide treatment decisions in these patients. See Video Abstract at http://links.lww.com/DCR/B990 .

Validez clnica del anlisis de adn del tumor circulante informado por el tumor en pacientes sometidos a ciruga de metstasis colorrectales: ANTECEDENTES:Los biomarcadores precisos para monitorear la carga tumoral y la respuesta en pacientes con cáncer colorrectal metastásico que se someten a cirugía podrían optimizar los regímenes de tratamiento.OBJETIVO:Este estudio explora la validez clínica de la cuantificación informada por el tumor del ADN tumoral circulante en sangre mediante secuenciación ultraprofunda.DISEÑO:Se analizaron muestras de resección de 53 pacientes con cáncer colorrectal en busca de mutaciones específicas del tumor en quince genes. Estas mutaciones se usaron para medir la presencia de ADN tumoral circulante en muestras de plasma recolectadas antes de la operación usando secuenciación basada en captura híbrida. Se realizaron mediciones postoperatorias adicionales una semana después de la cirugía en dieciséis pacientes.AJUSTES:El estudio se realizó en el centro médico de la universidad de Radboud.PACIENTES:Se incluyeron un total de 53 pacientes con cáncer colorrectal sometidos a cirugía de metástasis.PRINCIPALES MEDIDAS DE RESULTADO:La detección de ADN tumoral circulante.RESULTADOS:Se detectó al menos una mutación específica de tumor en todas las muestras de tumor. En muestras de plasma preoperatorias, se detectó ADN tumoral circulante en el 88% (37/42) de los pacientes sin tratamiento sistémico previo y en el 55% (6/11) de los pacientes que recibieron quimioterapia preoperatoria. Más concretamente, en el 0% (0/3) de los casos con respuesta patológica subtotal o parcial y en el 75% (6/8) de los casos sin respuesta patológica en la pieza de resección ( p = 0,06). En muestras de plasma postoperatorio se detectó ADN tumoral circulante en el 80% (4/5) de los pacientes con una resección incompleta y en el 0% (0/11) de los que tenían resección completa ( p = 0,003).LIMITACIONES:El estudio estuvo limitado por la heterogeneidad de la cohorte y el pequeño número de muestras de plasma postoperatorias.CONCLUSIONES:Estos datos indican que la detección de ADN tumoral circulante informado por el tumor en el plasma de pacientes sometidos a cirugía por cáncer colorrectal metastásico es factible y puede tener valor clínico en el control de la respuesta y la predicción de la enfermedad residual. Se necesitan estudios prospectivos para establecer la utilidad clínica del análisis de ADN tumoral circulante para guiar las decisiones de tratamiento en estos pacientes. Consulte Video Resumen en http://links.lww.com/DCR/B990 . (Traducción-Dr. Mauricio Santamaria ).

FIGURE 1.

Preoperative ctDNA analysis. A, Overview of all mutations found in tumor tissue and their paired preoperative plasma samples for all 53 patients. Different patients are shown horizontally. The colors show the number of alterations found in tissue, and the numbers show the number of tumor-informed mutations detected in ctDNA. The row marked as plasma presents the percentage of tumor-informed mutations detected in ctDNA. The row VAF indicates the mean VAF for that patient in the ctDNA. B, The number of mutant molecules per mL plasma plotted for every patient, comparison of the number of mutant molecules per mL plasma between patients with liver metastases and peritoneal metastases‚ and correlation of number of mutant molecules per mL plasma with estimated tumor load before surgery in cm. Median and interquartile range are shown. Tumor load of ctDNA negative samples is displayed in red. chemo = chemotherapy; ctDNA = circulating tumor DNA; MSI = microsatellite instability; VAF = variant allele frequency.

FIGURE 2.

Overview of clinical, plasma, and pathologic tumor characteristics. A, Patients with preoperative chemotherapy (n = 11). B, Patients with both preoperative (plasma 1) and postoperative (plasma 2) analysis (n = 16). Patients are ordered based on the mean VAF detected in ctDNA. Clin = clinical; cfDNA = cell-free DNA; ctDNA = circulating tumor DNA; VAF = variant allele frequency.