Congrats to Sunesis....

....who entered Phase I with SNS-032, a multi-CDK (2, 7, & 9) inhibitor for blood cancers.

The other prominent CDK inhibitors in development are from Cyclacel, who does not appear to have publicly identified which CDKs are are in their sights. (AZ also has a CDK4 program.)

The concern with targeting CDKs is that they are so fundamental to cell function that any therapy needs to be very, very well targeted, with above average biological knowledge to compensate for off-target effects.

Not to mention the fact that as nuclear proteins, delivery for a-CDK compounds is much more complex than say targeting RTKs.

Perhaps success by Sunesis or Cyclacel will increase interest in CDKs as targets.

Rational DD vs. Trial & error (HTS)

Skewed towards rational DD, there's a few quotes worth repeating:

"Many scientists have realized that blindly screening millions of compounds in the lab and hoping for a hit or a lead is an irrational drug design process that rarely pays off,"

"HTS starts at approximately $1 million per project, with no guarantee you'll find anything useful. "

"Structure-guided design helps to localize subtle features and different conformations in the binding pocket."

"The protein kinases exemplify a family where the potential exists to accelerate lead discovery and optimization by inferring between the massive amount of structural and chemical data from gene family members."

Other takeaways:
AZ is working on CDK4

CYC116

Cyclacel - which has a CDK inhibitor in P2 - also revealed that their Aurora inhibitor is near IND (CYC116). What's interesting, though, is that in this article (http://biz.yahoo.com/bw/061113/20061113005486.html?.v=1) Cyclacel reveals (I think for the first time) that CYC116 not only inhibits Aurora, but also VEGFR2. This could be a case of limited selectivity being spun as a positive, but if CYC116 is selective for just Aurora and VEGFR2, you'd have an anti-angiogenic cell cycle inhibitor, which would be very interesting, if effective.

Note, Cyclacel also said CYC116 was just about to IND this time last year, and while CYCC has ~$60M in cash on hand, the company's market value is only ~$90M