A Decade-Long Cancer Sequencing Project Yields “Unprecedented” Look at Cancer-Causing Mutations

Over 1,300 scientists worked for a decade to sequence the genomes of 38 types of cancer in a global study called the Pan-Cancer Analysis of Whole Genomes Consortium. Though genetic sequencing for cancer is not a new feat for scientists, this project provided an “unprecedented” look into how genetic mutations can contribute to cancer. Scientists pinpointed 705 mutations associated with tumor growth and found that cancer growth resulted from an average of four or five mutations. These mutations are called “driver mutations” and theoretically, individually tailored treatment could target these mutations to stop tumor growth at its source.

Scientists also found that one third of these “driver mutations” happen years or decades before cancer is found in a clinical setting. In these cases, the window for treatment of the genetic mutations prior to the cancer’s growth is significantly larger than previously thought. Scientists could potentially use these findings to create diagnostic tests that could identify cancer much earlier than is currently possible. Identifying and targeting driver mutations has been the basis for cancer drug discovery for a number of years. Drugs such as imatinib and ponatinib target driver oncogenes such as BCR-ABL, while drugs like brigatinib and crizotinib target driver oncogenes known as ALK and ROS.

The information obtained in the study is transformational, with one BBC report saying that the results of the project “provide an almost complete picture of all cancers.” However, to truly have an impact on cancer patients, their lives and their families, the research has to translate into applicable diagnostic tools and treatment plans, which requires clinical information.

Clinical information, such as family history and therapies utilized in cancer treatment, has been largely left out of previous genome sequencing studies because patient information is difficult to access, expensive to obtain and risky for patient privacy. Despite its complexity, clinical information is necessary to move the needle on cancer detection and treatment. According to a Nature editorial, “the future of cancer genomics lies in the clinic.”

This huge step forward in cancer research leaves much to be discovered. In five percent of cases studied, no driver mutations were found, leaving scientists still searching for answers. If pre-cancer diagnostic testing becomes possible, medical providers will need to know how to differentiate between problematic and benign mutations. The transformational research of this project has laid the groundwork to answer these questions and better fight cancer.

Using Non-Cancer Drugs to Treat Cancer

A study conducted by researchers at the Dana-Farber Cancer Institute and the Broad Institute of MIT and Harvard has shown that a variety of non-cancer drugs may also be effective as treatments for cancer. The study, which was published in the Nature Cancer journal, tested approximately 4,518 drugs against 578 cancer types and found almost 50 drugs showed some anti-cancer activity. This repurposing study is intriguing to scientists and doctors because the drugs have already been FDA-approved for safety, which means that the drugs could be accelerated into clinical trials for effectiveness against various types of cancer.

The drugs that were investigated through this study were previously used in medical areas vastly different than oncology. For example, one of the effective drugs is levonorgestrel, which is a hormonal drug used in birth control pills and emergency contraception. Also effective was disulfiram, which is used to treat alcohol dependence. The study was wide-ranging, aimed at giving researchers an understanding of which drugs could potentially be useful, or be modified to be effective, in oncology. This study is referred to as “repurposing” proven medicines from one indication to another.

The study also revealed previously unknown mechanisms for the studied drugs. For example, some of these drugs worked by activating or stabilizing existing proteins, which was effective against cancer even though most current cancer drugs work by blocking proteins. Most of the 49 drugs that did prove to have anti-cancer properties worked through a previously unidentified mechanism.

The discovery of unidentified mechanisms presents an additional opportunity for researchers. In addition to repurposing these into anti-cancer treatments, but they were also able to begin identifying other mechanisms that work against cancer that could inform new treatments for cancer. Understanding that activating or stabilizing a protein in some cases is effective against cancer opens up new avenues for brand new oncological drugs in addition to the repurposed treatments.

Overall, this repurposing study suggests an overall method to accelerate the development of new drugs to treat cancer. By finding which mechanisms work against cancer in other drugs, scientists will be able to create brand new drugs and push existing drugs into trials for effectiveness much more quickly. While this study did not produce any immediate cancer treatments, the information produced will help scientists push cancer research forward.