February 17, 2017 | by Denise Heady
City of Hope researchers and scientists constantly strive to find less invasive ways to help treat patients diagnosed with kidney cancer. Despite a wave of new targeted therapies being approved to treat the disease, many of those therapies have been challenging to use because of the difficulty in obtaining cancer tissue for genomic testing.
Now, researchers may have found a way to combat this problem: the liquid biopsy.
The liquid biopsy, using cell-free cancer DNA that is circulating in the patient’s blood, is an easy and less invasive method of accessing important genomic information in solid tumors, but had not yet been tested in patients with kidney tumors.
In a study led by City of Hope’s Sumanta K. Pal, M.D., assistant professor in the Department of Medical Oncology & Therapeutics Research and co-director of the Kidney Cancer Program at City of Hope, he and his team identified cancer-related DNA in about 80 percent of patients who had a liquid biopsy performed. A majority of the patients were found to have clinically relevant genomic alterations, including alterations in the TP53, VHL, EGFR, NF1 and ARID1A genes.
The results, based on data from Guardant Health, will be presented on Saturday, Feb. 18, at the 2017 Genitourinary Cancers Symposium, which is sponsored by the American Society of Clinical Oncology and the American Society for Radiation Oncology. The analysis of 224 patients diagnosed with metastatic renal cell carcinoma (mRCC) and tested with Guardant360 is the largest assessment of circulating tumor DNA in patients to date. Analysis of this large cohort demonstrated significant changes in circulating tumor DNA (ctDNA) profiles across patients’ clinical courses, which may have therapeutic implications.
“Until now, the only means of assessing kidney tumor DNA has been through biopsies of cancer tissue, a procedure which can be associated with risk of infection and bleeding,” said Pal. “The liquid biopsy circumvents this completely.”
Guardant360 has been used by more than 3,000 oncologists to identify somatic genomic alterations associated with targeted therapies in the tumor DNA of more than 30,000 patients with advanced cancer.
Many doctors rely on biopsies to create an individual treatment plan that is directed toward specific genomic changes in the patient’s tumor.
Because tumors evolve and develop resistance in response to treatment, the changes in ctDNA might provide key insights into how resistance to treatments for kidney cancer occurs. Pal and colleagues now aim to replicate this work in a larger study of patients to confirm the results.
This study also represents an example of City of Hope’s ongoing commitment to developing personalized medicine and targeted therapies. Personalized medicine, which offers physicians the ability to better diagnose, treat, cure and prevent diseases, depends on three factors: discovering the genetic causes of diseases, understanding why individuals respond to different therapies and translating this understanding into new diagnostic tests and therapies.