A Third Inhibitor is Withdrawn

Well, this is getting silly now.

The maker of the PI3K inhibitor Parsaclisib has withdrawn its New Drug Application with the FDA. This comes a little more than a week after Idilalisib was withdrawn from the market for Follicular Lymphoma, and about six weeks after Duvelisib was withdrawn.  

Unlike the other two PI3K inhibitors, Parsaclisib was not yet approved by the FDA. It had applied for accelerated approval, but after discussions with the FDA, it decided not to go through with the application. They were not confident that they would be able to meet the requirements. Like the other two, this was called a "business decision." The application would have covered relapsed/refractort Follicular Lymphoma, and MZL and MCL, two other lymphomas.

I haven't seen a whole lot of analysis or commentary about any of these withdrawals. On Twitter this morning, I saw someone comment that there would probably be more of this happening with NHL treatments, as the large number of treatments (especially PI3K treatments) would mean more competition, and so more data to show that this version of the treatment would be better than others -- either more effective or safer. Another commentor said everyone is afraid of bi-specifics.

As I said in my post about Idelalisib, it does seem we've reached a point where we (patients, doctors, the FDA) will need to start focusing on quality over quantity. It's great to have so many options for treatment, but if the differences between those treatments are minimal, then someone is going to win that competition. 

And as good as PI3K inhibitors seem to be (they seem especially popular as a third-line treatment, after two other treatments have failed), the treatments that have gotten the Lymphoma community so excited in the last few years have been R-Squared (Rituxan + Revlimid), CAR-T treatments, and more recently, bi-specifics. What do they al have in common? They are as good as, or better than, traditional chemotherapy. And by "better than," I mean they are either more effective (they work on as many patients as chemo does, for as long) or they are safer (with fewer or less severe side effects).

But really, the biggest thing that the "exciting" treatments has going for them is durability. They have shown that they can work for a long time before a patient needs another treatment. And that matters. 

When I was first diagnosed in 2008, the assumption about Follicular Lymphoma was that patients could expect a lifetime of treatment. The disease would become more aggressive over time, and treatments would need to become more aggressive as well, with less and less time between them. Maybe the first treatment would last 5 years, and then the next 2 years, etc.

That's certainly still the case for some patients. But if newer treatments are also providing durable responses, then we would have less need for a wide range of choices. In other words, there's less need (and maybe desire) for 10 treatments that will each last 2 years when we could have 4 treatments that each last 5 years. Fewer treatments means fewer side effects to deal with, and better quality of life.

At least that's what seems to be happening. Remember, I'm not a doctor or a cancer researcher. Just a Cancer Nerd -- a patient who reads a lot.

Whatever the case, I think we don't need to be worried about treatments being withdrawn from use or from the approval process. There are lots of options still available and lots more being developed. We can afford to be picky (and patient). 

I hope to give you some good news next time.