More needles, less haystack

Companies developing blood-based diagnostics for cancer inevitably grapple with the challenge of too little cancer-related genetic material in patient samples to make reliable diagnoses. Liquid biopsy newco Freenome Inc. is developing tests for early stage cancers that rely on markers from the more abundant, normal immune cells that respond to cancer -- and this month’s $65 million series A round shows investors are taking the approach seriously.

According to founder and CEO Gabriel Otte, Freenome's platform combines wet-lab isolation of cell-free DNA and RNA from exosomes and other sources with computational algorithms, and produces signature profiles of the nucleic acids in cancer cells versus healthy cells. Because the majority of cell-free genetic material captured comes from tumor-attacking immune cells, it generates a signal that is more robust, and therefore more reliable for diagnosis, than systems based only on tumor cells or tumor DNA, said Otte. In the absence of cancer, the signature for the cancer won't be detected in the sample...