When researchers at the University of Texas MD Anderson Cancer Center cracked open exosomes in blood, they never expected to find large fragments of DNA. Exosomes are nano-sized vesicles packed together by somatic cells to be secreted into body fluids, which then reach the bloodstream. Although Dr. Raghu Kalluri, chairman and professor in MD Anderson’s Department of Cancer Biology, was surprised to find nuclear material in a particle secreted by the cell, he says that the DNA found inside vesicles may be used as a genetic roadmap to any existing cancer cell, allowing a revolutionary tumor detection test. The traditional test for tumor identification is a biopsy of an existing tumor, meaning that a patient is already showing symptoms of cancer, and it might be too late for intervention.
Previously esoteric, exosomes are gaining a reputation of being powerful tools for diagnostics and drug delivery as more studies show their relevance in cellular health and communication. Dr. Douglas Taylor, Chief Scientific Officer of Exosome Sciences, a subsidiary of Aethlon Medical, began the quest to understand exosomes 35 years ago. He describes exosomes as “letters sent out from cells… to maintain the healthy state of a patient.” For researchers to interpret what the messages mean, they act like “the [National Security Agency] reading the mail” to uncover information about the transcriptome (protein content) of cells. All cells secrete exosomes, but when cells are diseased or transformed, they secret exosomes with different contents as a result of their change in gene expression. By reading the gene expression profile of cells, researchers can pinpoint the characteristic phenotype and genotype of a cell and determine its cancer status.
The therapies that first considered exosomes came from Aethlon Medical, where it was known that exosomes suppress immune cells in cancer patients. In order to improve outcomes of cancer therapy, they worked to eliminate exosomes from the blood. Now, the industrial focus on exosomes is geared toward diagnostics, where the key to unlocking their potential lies in the ability to capture and open the vesicles to see what is inside. For example, Exosome Diagnostics is developing a test that will capture exosomes and use the RNA inside to detect mutations associated with prostate cancer.
Aethlon Medical understands that the power of exosomes is inaccessible without both capture and analysis. A spin-off of Aethlon’s ADAPT System, the Hemopurifier, is a first-in-class medical device that enables the capture of pathogens and exosomes. ELLSA, a product from Exosome Sciences that stands for Enzyme Linked Lectin Specific Assay, is now being developed to assay exosomes in real-time to look for viral infections, pregnancy complications, birth defects, cardiovascular disease, and neurodegeneration.
Other public lifesciences companies such as Life Technologies, Inc. and Eli Lilly & Co. are capitalizing on the diagnostic power of exosomes. In order to expedite technology development, many companies are entering into strategic partnerships. For example, Eli Lilly & Co. partnered with Exosome Diagnostics in September and is contributing to the prostate cancer test by identifying gene mutations and exosome expression levels in blood that predict drug response and disease recurrence. A $13.6 billion deal underway will allow Thermo Fisher Scientific, Inc. to acquire Life Technologies, a leader in exosome diagnostics, but regulatory hurdles may require some divestures. Life Technologies is an attractive acquisition because it is a lead developer of the process of capturing, isolating, and analyzing exosomes from body fluids; it also produces kits for isolating specific subpopulations, intact exosome analysis, and cargo isolation and analysis.
All companies involved look to stay at the forefront of exosome research. Popular Science named exosome cancer diagnostics on of the 20 breakthroughs that will shape the world in 2014. Evidently, Wall Street will soon see the value in this technology, and more companies will rally behind the use of exosomes. Such a boon would greatly please Dr. Taylor; after all, it is every researcher’s hope that their work someday directly benefits the world.