On the technical side, I think we need to master data integration across many sources. For example, health records, sequencing, and clinical trials all contain tremendous amount of data, but combining them and generating knowledge is very hard. Much of this is just translating what web companies have developed, and understanding how to make it palatable to health researchers, patients and companies. That's partly technological, but honestly, the technological problems are pretty small; we could make a tremendous forward progerss in cancer if everybody's health records were fully digitalized, normalized and harmonized, and available to cancer researchers (even ones not doing trials) for aggregation and analysis. This is one reason I've donated my genome to the public domain- but we need millions more to do this.
Also, the way we fund and execute most health research is very broken. We could organize and manage this far better than we can- but it would take a lot of changes and stepping on a lot of toes. Again, there's a tech side, but the tech side is "easy" compared to the politics and money parts.