Thursday, December 29, 2016

CR30: A New Way to Measure Effectiveness

While I've been looking at stuff from the ASH conference earlier this month, there's been even more research on Follicular Lymphoma that has been posted online. This one came out just yesterday in the Journal of Clinical Oncology: "Thirty-Month Complete Response as a Surrogate End Point in First-Line Follicular Lymphoma Therapy: An Individual Patient-Level Analysis of Multiple Randomized Trials."

If you follow clinical trials for Follicular Lymphoma, then you know that a couple of things are true: first, the best measure of a trial's success is Progression Free Survival (PFS). This is a measurement of how long the lymphoma takes to come back (if there was a Complete Response) or get worse (if there was a Partial Response). Overall Survival (measuring how long people live) would be great, but with an indolent lymphoma like FL, that's not a great measure of success. So we use PFS.

The second thing that is true is that PFS can go on for a long time. If a median PFS is necessary (that is, half of the patients in a trial have achieved a PFS), then the process can go on for a long time -- 6 or 8 years for some treatments.

That's great news for individual patients -- it means lots of us will have a long time before we need another treatment (I'm getting close to 7 years since my last Rituxan).

But it's not as good for us as as a group. A regulatory body (like the FDA in the U.S. or the EMA in Europe) might want to see a final PFS number before approving a treatment. That's a long time to wait.

The researchers in this study looked at a number of clinical trials conducted since 1990, involving over 3800 patients, and found that 30 months was a good substitute for median PFS. In other words, if the patients in a trial had a median PFS of 30 months, it was likely that the PFS would actually go on for some time.

Interestingly, they also tried to measure this with a 24 month time period, and found that it was not as accurate as the 30 month time.

It is important to note that this does NOT mean that an individual patient who has reached 30 months without needing treatment is not going to need treatment for a while after that. The number is not meant to predict individual patients' success with a treatment.

So what is it good for? Well, if agencies like the FDA and EMA accept it, it could mean that clinical trials could be shorter, and new treatments could become available to patients a little sooner. (One problem, though, is that looking at only the PFS rate means long-term side effects are not being measured, though I'm not sure how much that's taken into consideration anyway. Short-term side effects definitely are, but not necessarily long-term.)

So we can call this one "helpful down the road" -- we won't see the effects directly when we sit in the chair in a treatment room, but what they give us might be available to us because of it.

I'll look for something more exciting to report on next time.....

1 comment:

William May said...

I fully support PFS as the metric for follicular lymphoma. This would make new treatments available sooner for folks who have run out of options. My wife who has follicular lymphoma ran out of options after four treatments. Her life was saved by an NIH CAR-T clinical trial - she has been in complete remission for 10 months so far. Had she not been accepted into this wonderful clinical trial she would probably be deceased now.