5F9 Given Fast Track Review for FL

Great news last week for 5F9 -- the FDA has granted it Fast Track Review for Follicular Lymphoma.

What? You haven't heard of 5F9?

 To be honest, I hadn't either, until last week.

When a treatment is given a Fast Track designation by the FDA, it means the FDA believes it will address a "unmet medical need" for a "serious condition." Because of this, the designation means the FDA will give some extra help in the development of the treatment (like extra meetings and written communication with the FDA and advice on clinical trial design) and possible faster review than usual.

The idea is, if the treatment has the potential to do something great, the FDA wants to get it to patients as quickly and easily as possible (assuming it is shown to be effective and safe, of course).

Fast Track also kind of implies that the treatment is still fairly early in the process, since there will be extra help for development.

And that's probably why you've never heard of it (and why I've never heard of it, even though I like to think of myself as pretty well informed on these things) -- 5F9 got the designation based on results of a phase 1b/phase 2 clinical trial -- still very early.

5F9 is a monoclonal antibody. (I assume, if it is approved, it will get a new name, probably something with at least one X, Y, or Z in it.)

For comparison, think of our old pal Rituxan -- also a monoclonal antibody. Rituxan targets CD20, a protein on the surface of B cells. When Rituxan finds CD20, it helps to destroy the cell.

Same with 5F9, except it targets the CD47 protein. CD47 is a protein found on all cells, but it is over-expressed on certain cells -- that is, too many copies of it get made.

That's important, because CD47 has a special job. It is known as a "marker of self." In other words, when immune cells go around looking for cells that don't belong (usually things like viruses and bacteria), when they come across CD47, it's a signal that the cell belongs, and shouldn't be attacked. (I really like that, when I was reading up on CD47, several articles from medical journals kept calling CD47 a "don't-eat-me signal." That's good, clear writing.)

So that's the deal -- 5F9 looks for CD47 and takes out those cells. Get rid of the "don't eat me" signal, and the immune cells go to work.

Just how effective is it?

No idea. The results from the phase 1b trial will be released sometime in the next few weeks. (Maybe during the ASCO conference next month?)

5F9 looks like it could do some excellent things. The Fast Track covers  Follicular Lymphoma and Diffuse Large B Cell Lymphoma (DLBCL), and there are also trials going on for Ovarian Cancer, Bladder Cancer, Colorectal Cancer, and an aggressive Leukemia.

Of course, it's early in the process -- even a process that might be sped up a little. And a phase 1b trial is going to involve a fairly small number of patients.

Still, I'm looking forward to hearing more detail in the next few weeks. I assume it will be good news, given the FDA's encouragement, but it will be good to see actual data on how effective and safe it is.