ASCO: PI3K Inhibitors

More from ASCO.

PI3K Inhibitors have been an area of excitement in blood cancers for a few years. Like all inhibitors, PI3K inhibitors stop something from happening. Cancer cells go through a series of paths or steps to grow and live. Researchers have been able to identify what those paths are, and then how to interrupt or inhibit those paths.

PI3K stands for Phosphoinositide 3-kinase, which is a group of enzymes that are necessary for cancer cells to live and grow.

There are actually three PI3K inhibitors that have been approved (by the FDA) for Follicular Lymphoma.  Duvelisib was approved in 2018 for relapsed/refractory FL, and Copanlisib was approved about a year before that for relapsed FL. Idelalisib was approved in 2014 for relapsed FL.

There were a couple of nice presentations at ASCO this year that dealt with PI3K inhibitors.

One was about Copanlisib: "Long-Term Follow-Up of Patients (pts) with Relapsed or Refractory (R/R) Follicular Lymphoma (FL) Treated with Copanlisib." Interestingly, the reserach deals with both relapsed (a treatment worked for w while, then stopped working) and refractory (a treatment didn't work at all) patients.

This research looked at the patients who were in the trial that resulted in the FDA approval. 104 patents in the trial were given Copanlisib. In the current analysis, 59% had a response, with 20% having a Complete Response. The median for how long the response lasted was a little over a year. The CR numbers are higher than they were for the first analysis -- it was under 15% at that point. That included patients with "higher grade disease." Side effects were manageable, with no new long-term effects popping up after two additional years of study.


It's nice to see long-term results, even after approval.

Another presentation focused on a PI3K inhibitor called ME-401. This one is so new that it doesn't even have a cool name yet. The presentation gave the results of a phase 1b clinical trial. As part of the trial, 48 Follicular Lymphoma patients were given ME-401, by itself or with Rituxan. After a  median follow-up of about 9 months, 28 of the patients remained in the study. Responses were good, with 79% of patients of patients who had ME-401 getting a response, and 78% of patients getting the Rituxan combo getting a response. Patients were either given treatment every day, or for one out of four weeks. Those on the one week out of four had fewer side effects.

This is a very early study, with not many patients in it -- that's how stage 1 trials work. But they are good results, even if they're early, and we may see more of this treatment in the next couple of years, if they are able to move onto phase 2 trials.

It's all a nice reminder that, even if a first treatment doesn't work as well as we'd hoped, we have a lot of options for second and third treatments.