Obtaining sufficient tumour tissue for oncology testing can be challenging, particularly when there is an insufficient biopsy sample, and invasive procedures pose a health risk to the patients. This is especially true for non-small cell lung carcinoma (NSCLC), where 27%–31% of patients are unable to provide a suitable specimen upon diagnosis. One area of active research in oncology testing has been the evaluation of alternative sources of testing material. Liquid biopsy refers to the analysis of any tumour-derived material, circulating in the blood or any other body fluid. The detection of mutations via circulating tumour DNA (ctDNA) found in plasma has been rising in popularity due to its minimal invasiveness.
On 7 August, Guardant Health announced the Food and Drug Administration (FDA) approval of its novel liquid biopsy comprehensive tumour mutation profiling test across all solid cancers. This is a landmark approval for cancer testing as Guardant Health’s liquid biopsy is the first of its kind to genetically profile tumours anywhere in the body from a single blood draw. The FDA approval of this test includes its approval as a companion diagnostic for identifying patients with metastatic NSCLC based on the presence of mutations in the EGFR gene. Lung cancer is the current leading cause of cancer-related deaths worldwide with NSCLC comprising 80%–90% of all lung cancers. As such, the need for this test is very high.
On 27 August, Foundation Medicine, a Roche company, received FDA approval for its FoundationOne Liquid CDx, a multi-cancer comprehensive liquid biopsy test. Foundation Medicine’s test is broader than Guardant Health’s, covering more than 300 cancer-related genes. In addition to single-gene alterations, Foundation Medicine’s test also reports on the presence of multi-gene signatures namely microsatellite instability and blood tumour mutational burden, which can help guide the use of cancer immunotherapies.
The genomic analysis of ctDNA has the potential to offer insight across multiple metastatic sites. This is particularly valuable in settings with increased genomic heterogeneity such as in patients with treatment resistance. Some key opinion leaders (KOLs) interviewed by GlobalData have indicated that despite the fact that the test has some sensitivity issues, liquid biopsies are a cheaper alternative and the minimally invasive aspect of the technique improves patient satisfaction. Other KOLs noted the potential for liquid biopsies to integrate the overall cancer burden in patients with numerous metastases in different locations. GlobalData predicts an increased usage of liquid biopsies in the future due to the benefits they offer patients with metastatic recurrence.
Liquid biopsy is revolutionising cancer tests as it is non-invasive, precise and provides faster turnaround time for results compared to traditional solid tumour biopsy. While DNA sequencing methods such as Sanger sequencing have been considered the gold standard for detecting many genetic mutations associated with cancer, these techniques have lower sensitivity, and thus, require samples with a higher percentage of mutated DNA. As such, the use of ctDNA will be important for detecting cancerous mutations where tumours are hard to resect. Furthermore, the use of highly sensitive assays such as next-generation sequencing (NGS) will aid in the detection of cancerous mutations. As sequencing technology like NGS becomes more developed and its costs decrease, GlobalData expects these techniques to be more frequently used to test for mutations in cancer.