During his first speech to a joint session of Congress, President Trump vowed to "slash the restraints" put on drug development by the Food and Drug Administration. The latest approval for an already successful cancer drug from Merck & Co. (NYSE: MRK) may not have been exactly what he had in mind, but it is a huge step in a wildly different direction. For decades, we've known that certain genetic markers are associated with certain types of cancer, but using this knowledge to treat patients has been stymied by the way the FDA approves drugs.