Circulating tumor DNA analysis as a real-time method for monitoring tumor burden in melanoma patients undergoing treatment with immune checkpoint blockade

Abstract

BackgroundAssessment of therapeutic activity of drugs blocking immune checkpoints such as CTLA-4 and PD-1/PD-L1 can be challenging, as tumors may seem to enlarge or appear anew before regressing, due to intratumoral inflammation. We assessed whether circulating tumor DNA (ctDNA) levels could serve as an early indicator of true changes in tumor burden in patients undergoing treatment with these agents.FindingsTumors from 12 patients with metastatic melanoma undergoing treatment with checkpoint blocking drugs were analyzed for the presence of hotspot somatic mutations in BRAF, cKIT, NRAS, and TERT. Plasma was collected serially from each patient and levels of ctDNA were compared with radiologic and clinical outcomes.In 5 of 10 patients studied, mutations were detected in BRAF(1), NRAS(2), TERT(1) and ALK(1). Analysis of plasma from 4 of 5 patients identified mutations identical to those found in tumor specimens. Plasma ctDNA levels ranged from undetectable (<0.01%) to 5.5% of total circulating cell-free DNA. In 3 patients, increasing ctDNA levels correlated with progressive disease assessed by radiography. In one patient, ctDNA levels increased after undergoing a needle biopsy of a tumor deposit. In another patient, ctDNA levels increased initially as lymphadenopathy progressed by examination, but then became undetectable 3 weeks prior to clinical improvement.ConclusionsLevels of ctDNA correlated with clinical and radiologic outcomes, and, in one case, preceded eventual tumor regression. Further prospective analysis is required to assess the utility of ctDNA as an early biomarker of clinical outcomes in patients receiving immune checkpoint blocking drugs.Electronic supplementary materialThe online version of this article (doi:10.1186/s40425-014-0042-0) contains supplementary material, which is available to authorized users.

Prediction of Response to Immune Checkpoint Inhibitor Therapy Using Early-Time-Point18F-FDG PET/CT Imaging in Patients with Advanced Melanoma

“…Small trials have shown that circulating tumor DNA level changes can mirror radiologic changes in tumor burden and may predict eventual response to ICI (34,35). These emerging technologies, which require only serial blood sampling and laboratory analysis, may compare favorably with PET/CT in terms of feasibility and accessibility among an increasing population of patients undergoing therapy with ICI.…”

Use of Liquid Biopsies in Clinical Oncology: Pilot Experience in 168 Patients

“…Detection of cell-free DNA was first described in 1987 by Stroun and collegues (8), and numerous articles were published in the past few years, indicative of a growing interest in this noninvasive diagnostic method (9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Potential application scenarios include using ctDNA to supplement or substitute for tissue biopsies, especially in cases where tissue biopsies are risky or the quantity/quality of the tissue biopsied does not allow testing, and to use repeat sampling and genomic profiling to detect tumor evolution, response, and resistance (6,(19)(20)(21). Of interest, fluids such as urine can also be used to detect ctDNA (22,23).…”

Development and validation of an ultra-high sensitive next-generation sequencing assay for molecular diagnosis of clinical oncology

“…With the advantages of noninvasive and overcome tumor-heterogeneity (42)(43)(44), the sequencing of plasma sample still needed more study. To reduce the sequencing errors confound with rare mutations, a NGS method termed Duplex sequencing was developed these years and may be useful in future plasma sequencing (45)(46)(47).…”