NantHealth Inc., the Culver City healthcare technology company founded by billionaire Patrick Soon-Shiong, has received Food and Drug Administration approval to market a genetic mapping tool that measures the rate of cell mutations in tumors.

The Nov. 12 announcement marks the first FDA approval of a product that sequences large segments of genes using a method called whole exome sequencing.

In NantHealth’s tool, the sequencing is applied to tumors to determine the rate at which cells mutate and become malignant, which is called the tumor mutation burden. That in turn is used to determine which patients would fare best with immunotherapy treatments for cancer.

According to Soon-Shiong, NantHealth’s chief executive, studies have shown that immunotherapy-treated patients with high rates of cell mutation had better outcomes compared with those with lower mutation rates.

With FDA approval in hand, NantHealth can now take on competitors in the field of mapping genomes to gauge disease risk, including Salt Lake City-based Myriad Genetics Inc. and Burlingame-based Color Genomics Inc.