As new immunotherapy drugs hope to turn metastatic cancer into a chronic manageable condition, or at least significantly prolong life in the near term, investors are understandably excited about their potential.

And one company at the forefront of this move, Bristol-Myers Squibb, just got a huge upgrade today from Wall Street titan Citigroup, sending shares 5% higher. Citi moved Bristol from "neutral" to "buy" and upped its old $33 price target to $55 per share.

In this video, health-care analyst David Williamson discusses Bristol's big upgrade and gives a few of his key takeaways from the report.

Follow David on Twitter: @MotleyDavid.