Liquid Biopsy Promising in Spotting Kidney Cancer

By David Douglas

July 02, 2020

NEW YORK (Reuters Health) - An assay employing plasma and urine cell-free (cf) DNA methylomes is capable of classifying patients across all stages of renal-cell carcinoma (RCC), according to preliminary studies.

The technique, called cell-free methylated DNA immunoprecipitation and high-throughput sequencing (cfMeDIP-seq), provides "exquisite sensitivity . . . for detecting early-stage kidney cancer in both plasma and urine," Dr. Matthew L. Freedman of Harvard Medical School, in Boston, told Reuters Health by email.

"Kidney cancer," he added in a statement, "is one of the hardest tumors to detect, because it doesn't shed as much DNA as other tumors, that's where this test performs really well."

In a paper in Nature Medicine, Dr. Freedman and colleagues note, "Although approximately 35% of RCC cases are diagnosed when the disease has spread beyond the kidney, no US Food and Drug Administration-approved blood or radiologic test exists to screen the general population for RCC."

In the first independent validation of cfMeDIP-seq in detection of RCC, the researchers evaluated samples from 99 patients with RCC ranging from stage I to IV. They also analyzed samples from 15 patients with stage-IV urothelial bladder cancer and 28 healthy, cancer-free controls,

Using plasma the team reported "near-perfect" classification of patients across all stages of kidney cancer. The area under the receiver operating characteristic curve was 0.99.

The corresponding value with urine-based classification (0.86) was not as accurate, say the authors, but "we believe that performance can be improved through technical and computational optimization."

"Provided further studies confirm our findings," Dr. Freedman concluded, "we believe that screening in high risk populations could lead to decreased mortality from this disease."

Dr. Sumanta K. Pal, co-director of the Kidney Cancer Program at the City of Hope, Duarte, California, who was not involved in the study, told Reuters Health by email, "Patients often ask if there is anything that could have been done to diagnose their kidney cancer sooner."

"To date," he said, "a screening tool (like mammograms for breast cancer or a PSA test for prostate cancer) has remained elusive - this study offers a potential avenue for introducing screening for kidney cancer."

The study had no commercial funding, but Dr. Freedman and three of his coauthors are listed as inventors on a related patent application.

SOURCE: Nature Medicine, online June 22, 2020.