FDA Fast Track Designation for EO2463

Last week, the FDA grated Fast Track designation for a new immunotherapy treatment called EO2463. (It will probably get a cooler name soon.)

Some reminders before we go any further: Fast Track designation means that a proposed treatment has the potential to do something new, and so it gets extra help from the FDA to help it through the approval process. Its a way of trying to get treatment to a group that has great need for treatment. In this case, that group is Follicular Lymphoma patients. (The news article about this is not clear about the specific population of FL patients, though the National Cancer Institute page for the clinical trial specifies relapsed/refractory patients with FL and some other indolent blood cancers.)

 Immunotherapy is a group of treatments (like chemotherapy is a group of treatments) that uses the body's immune system to work against the cancer. Our immune systems are usually good at fighting off invaders, like bacteria or viruses). But cancer cells aren't invaders -- they are our own cells, but they refuse to die like they are supposed to. So immunotherapy treatments usually work by either changing our immune cells to find and fight the cancer c ells, or changing the cancer cells so they can be recognized by our immune system as invaders.

EO2463 is a very interesting treatment that takes a unique approach to identifying tumor cells. It's a little complicated, so I've tried to do a bunch of reading and watching to help me understand it. (This video helped.)

The company that makes the treatment focuses on bacteria in our guts. Gut bacteria is kind of big news these days, as researchers are looking into all kinds of ways that our gut biome affects our health. (Though not all of those claims have solid evidence.)

The role of gut bacteria in this treatment is different. The company uses Artificial Intelligence to identify over 20 million different proteins that exist in the gut. Their AI program can help identify proteins that are very similar to those that exist in the body, especially proteins that exist on certain cancer cells.

That distinction between the gut bacteria proteins and the human proteins is important. The bacteria in our gut play important roles, but they aren't meant to leave the gut. If they do leave it, our immune system takes over. Immune cells are meant to recognize and fight off invaders (like bacteria or viruses). When they encounter one, they eliminate it and then remember it, so if they encounter it again, they can eliminate it very quickly. Gut bacteria are included on that list of invaders. As long as they stay in the gut, they are welcome to hang around, and the immune system leaves them alone.

So we have two things happening here. First, you have gut bacteria that are considered invaders if they leave the gut. Second, you have proteins from the bacteria that are very similar to proteins on cancer cells, like the CD20 protein that is on the surface of Follicular Lymphoma B cells. 

When you put those two things together, you can develop a cancer treatment. Create a treatment that targets CD20 (and some other proteins) but create it in such a way that it tells immune cells that the cancer cell is really a bacteria that escaped from the gut and needs to be eliminated. Because the treatment is engaging an immune cell called a Memory T Cell, which remembers invaders, the thinking is that the treatment will be long-lasting.

[A note to you language nerds: I know that "bacteria" is the plural form of "bacterium," but I'm calling a single one a "bacteria" anyway because I think it sounds better. Shakespeare made up words, too, and it's my blog, so I do what I want.] 

The Fast Track designation was earned by the results of the SIDNEY clinical trial. This is a phase 2 trial involving 60 patients split into 4 cohorts. As I said above, there are several different blood cancers being targeted in the trial. Patients are given EO2463 on its own and in combination with R-Squared or one of its components, Rituxan or Lenalidomide/Revlimid. 

The early results are promising. The first 13 patients have an Overall Response rate of 46%, with no severe side effects. The makers of the treatment see this as a possible alternative to watching and waiting (though it's not clear if they are targeting untreated patients.)

I have to say, I'm kind of fascinated by the approach, using AI to identify possible targets based on gut bacteria. But there are also lots of questions to be answered -- as is always the case with a phase 2 study. My guess is that there will be more information at the ASH conference, which is happening in less than 2 months. 

But Fast Track is no guarantee of success. This is definitely one that I will keep an eye on.