Editor's Note: In the video below, Michael Douglass indicates that only a subset of patients in the phase 1 trial for bemaciclib had breast cancer. All of the patients in the phase 1 trial had breast cancer, but subsets had different types of breast cancer. The Motley Fool and the analyst regret the error.

The American Association for Cancer Research's meeting last weekend yielded some big news from Pfizer's (NYSE:PFE) and Amgen's (NASDAQ:AMGN) palbociclib and Eli Lilly's (NYSE:LLY) bemaciclib. These drugs, which are part of the new CDK 4/6 inhibitor class, have generated a lot of excitement, particularly given the recent data releases.

Palbociclib generated a statistically significant, 10-month increase in progression-free survival (PFS) in a phase 2 trial, while bemaciclib reported about a 9 month median increase in PFS for hormone receptor positive breast cancer patients in its phase 1 trial.

Some analysts have speculated that Pfizer might seek an early submission to the FDA based on the palbociclib trial data so far, and investors are going to want to watch these companies and drugs very closely for the next release of data.

In this video from Tuesday's Market Checkup, Motley Fool health care analysts David Williamson and Michael Douglass discuss the recent drug data and what that means for investors moving forward.

David Williamson owns shares of Pfizer. Michael Douglass has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.