New Options for Colorectal Cancer

We are learning that the most successful way to treat cancer is to take aim at a good target. So what makes a good target? Quite simply, it should represent the driver that is inducing the cancer cell to grow and spread. The catch? There usually is not a single driver, and it may be different from one type of cancer to another, or even among individuals with seemingly identical cancers.

We are just now starting to develop ways to personalize medicine by identifying individual drivers, but at the current time, most therapies attack the consequences of the drivers, such as rapid cell division—this is how chemotherapy works. Yet major side effects result, as normal cells are also affected. Until recently, if surgery was not curative, chemotherapy represented the only therapeutic handle we had for colorectal cancer—and while these regimens have been refined, their impact is still modest.

As you will read in this issue of CURE, we have now moved to a different target for colorectal cancer—the addition of drugs that inhibit tumor blood vessel growth. In a process known as angiogenesis, the blood vessels are induced by tumor cells to grow and thereby form a delivery system of oxygen and nutrients to help cancer grow.

We still don’t know why colorectal, as well as some other cancers, appears to be preferentially affected by these therapies. The antibody Avastin (bevacizumab) continues to be an important drug to augment survival for patients with advanced colorectal cancer, even though it is usually not curative. Just this past year, two new drugs were approved that work on other targets—Zaltrap (ziv-aflibercept) and Stivarga (regorafenib). However, because angiogenesis is still not the primary driver of cancer but a consequence of several underlying genetic changes in cancer cells, there is more work to do, and we expect that more comprehensive molecular profiling will get us closer to the “drivers.”

This issue of CURE highlights the road of progress in colorectal cancer and the remaining challenges. Of course, we also get a word in about prevention and early detection—the first lines of defense against cancer.