FDA Approval: Tazemetostat for Follicular Lymphoma

Some FDA Approval News in the last week: Tazemetostat, also known as Tazverik. Tazemetostat is an EZH2 inhibitor.

EZH2 is short for "Enhancer of Zeste Homolog 2." I'm not sure how much it's worth breaking this down, but basically, EZH2 is an enzyme that is controlled by the EZH2 gene. It's job is to regulate tumor growth, so when there is a problem with it, tumors grow.

Tazemetostat is an inhibitor, which means it stops something from happening. In this case, it stops the EZH2 that isn't doing its job. So: cancer cells grow because EZH2 is letting them. Tazemetostat comes in and tells EZH2 to get back to work and stop those cancer cells.

The approval is for Follicular Lymphoma patients who are dealing with one of two situations: 1) a test shows that that they have an EZH2 gene mutation, and they have already had at lest two treatments already, or 2) the patient has no satisfactory treatment alternative.

That first one sounds great. There were two groups in the trial that led to the approval. One involved 42 patients with EZH2 mutation. The Overall Response Rate was 69%, with 12% getting a Complete Response and 57% getting a Partial Response. The second trial involved 53 patients with Wild-Type EZH2 mutation (a different type of mutation). In this group, there was a 34% Response Rate, with 4% getting a Complete Response and 30% Partial. About 30% of patients in the trial had serious side effects, and 8% of patients had to stop the trial because of it.

Tazemetostat is the first FDA approved treatment for patients with an EZH2 mutation. That mutation can affect a whole bunch of cancers. Having a treatment That targets it is important.

I'll be honest -- I'm having a hard time getting excited about this one. (And I say this while reminding everyone that I am not a doctor or a cancer researcher -- I'm just a cancer patient who reads a lot.) Part of my muted excitement comes from this affecting a fairly small group of FL patients. Not all of us have it; one study put it at "more than 25%" of us (I assume it's not much more than 25% or they'd have said so). And while EZH2 mutation is very serious, and this will help those who have that mutation, the numbers are very good, but the Complete Responses are kind of low.

And that's what concerns me about the second approval -- patients who have no satisfactory treatment alternative. That's going to give oncologists some room to use this. It will probably be their decision when it comes to figuring out whether or not there are alternatives.

The FDA gave this an Accelerated Approval. This means that, essentially, clinical trials will continue to make sure Tazemetostat is as effective and safe as the early trials seem to show. That's a good thing. It will give doctors more data to help determine which patients this could be useful for.

In general, I think that more treatments are a great thing. More arrows in the quiver, as an oncologist told me years ago. More choices to go to, when the ones we've tried have stopped working.

And this one is no different. Another choice is good, especially for patients with the EZH2 mutations. It will be interesting to see what happens as clinical trials continue.