Therapy for Diffuse Astrocytic and Oligo...

This guideline, clinical tools, and resources are available at http://www.asco.org/neurooncology-guidelines. Read the full text of the guideline and review authors’ disclosures of potential conflicts of interest in Journal of Clinical Oncology.

Brittany Harvey: Hello and welcome to the ASCO Guidelines podcast, one of ASCO's podcasts delivering timely information to keep you up to date on the latest changes, challenges and advances in oncology. You can find all the shows, including this one at asco.org/podcasts.  

My name is Brittany Harvey and today I'm interviewing Dr. Jaishri Blakeley from Johns Hopkins University School of Medicine and Dr. Nimish Mohile from the Department of Neurology and Wilmot Cancer Institute at the University of Rochester Medical Center, co-chairs on “Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: American Society of Clinical Oncology-Society for Neuro-Oncology Guideline Rapid Recommendation Update.” 

Thank you for being here today, Dr. Blakeley and Dr. Mohile. 

Dr. Jaishri Blakeley: Thank you. 

Dr. Nimish Mohile: Thank you for having us. 

Brittany Harvey: And then before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO Conflict of Interest Policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Blakeley and Dr. Mohile who have joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes.  

So then, to jump into the content here, Dr. Mohile, could you start us off by describing what prompted this rapid update to the ASCO-SNO therapy for diffuse astrocytic and oligodendroglial tumors in adults guideline, which was previously published in 2021? 

Dr. Nimish Mohile: Yeah. So the key reason for this update is the publication of a study in 2023. And this was a study called the INDIGO study that looked at a new class of therapies, something called IDH inhibitors. And in this study with a drug called vorasidenib, changed how we think about the treatment of oligodendrogliomas and astrocytomas, so particularly the grade 2 oligodendrogliomas and grade 2 astrocytomas. Because of the results of that study, we decided that we needed to do an update to inform clinicians about some of these changes and how we might approach these tumors differently today. 

Brittany Harvey: Great. I appreciate that background. So then, based off the new data from the INDIGO study, what are the updated and new recommendations from the expert panel? 

Dr. Nimish Mohile: So the key findings from the INDIGO study involved people who had grade 2 astrocytomas and grade 2 oligodendrogliomas. And in the setting after surgery, they were treated with vorasidenib, and what they found is that this delayed the time to next intervention. And the key aspect of that is that it delayed when we could start radiation and chemotherapy in these patients.  

So what we did in the guidelines is that for both low grade oligodendrogliomas and low grade astrocytomas, we added one additional guideline statement. Our previous guideline in 2021 offered the options for observation or treatment with radiation and chemotherapy. And now in this guideline, we have options for observation, treatment with vorasidenib in those in whom we feel it is safe to defer radiation and chemotherapy, and then treatment with radiation and chemotherapy. So we've added in an additional option here. And the key message of the guideline is really on how, as clinicians, we think about using the vorasidenib and what the ideal setting for using the vorasidenib is. 

Brittany Harvey: Excellent. It's great to hear about this new option for patients. So then you were just talking about how we think about who to offer this IDH inhibitor to. So, Dr. Blakeley, what should clinicians know as they implement these new recommendations into practice? 

Dr. Jaishri Blakeley: Yes. So, first and foremost, let's go back to 2021, and a key note from those guidelines was the importance of molecular testing. And at that point, the importance of molecular testing, which in large part was focused on IDH1 or IDH2 mutations, was prognostic. We could say there's a difference in an IDH1 mutant astrocytoma and an IDH1 wild type astrocytoma, but we didn't have a specific therapeutic recommendation attached to that, like Dr. Mohile just said. And the big shift here is now we have a specific therapeutic for that population with IDH1 or IDH2 mutant glioma.  

So for clinicians, we hope that they've been getting molecular testing on newly diagnosed glioma already, but now there's an additional motivation to do so because it may change your treatment plan in the right circumstance. So since the publication of the phase III INDIGO study that Dr. Mohile mentioned, and the FDA approval of vorasidenib, if you meet the specified criteria in the clinical trial - which the guidelines point out is a little different than what's on the FDA label, so clinicians might want to dig into that a little bit - then there is a treatment option that is new and different than combined chemoradiation or radiation alone or observation. 

Brittany Harvey: I appreciate those clarifications there.  

So then also, Dr. Blakeley, how does this update impact patients with astrocytic or oligodendroglial tumors? 

Dr. Jaishri Blakeley: So first, patients also should know if they have IDH mutant gliomas. And this update only applies to people with IDH1/2 mutant glioma. Perhaps, we're not sure, it might only apply to people who are in the newly or newly-ish diagnosed category because the INDIGO study required that people were within the first five years of their surgical diagnosis and had not had other treatment. So there are a lot of people who have astrocytoma or oligodendroglioma who may or may not know their IDH1/2 status and may have already had another therapy - this update doesn't apply to them. We hope that future research will teach us about that. This update is for people who are newly diagnosed and just starting the journey to figure out the best therapy. It does say that if you do have that IDH1/2 alteration in your tumor, there is a drug therapy that is different from the drug therapies we would offer gliomas that do not have the IDH1/2 mutation. 

Brittany Harvey: Absolutely. I think both that emphasis on molecular testing is very important and also thinking about that study inclusion criteria and how it impacts who's eligible for this treatment.  

So then finally, Dr. Mohile, what are the outstanding questions about vorasidenib or other interventions for gliomas in adults? 

Dr. Nimish Mohile: I think the key question for clinicians is exactly who we're going to use this in. The challenges with inclusion criteria in clinical trials is they don't actually always match what we're seeing in the clinic. And I think it brings up the question of, in low grade oligodendrogliomas which we think of as very slow growing tumors, do we have the option outside of the strict inclusion criteria to use that drug in other settings? I think it brings up the question for some clinicians in some of the higher grade tumors, in the grade 3 tumors, we don't yet have data in that area and our guideline doesn't address that. But I think some will be asking what the clinical activity of vorasidenib is in that setting. There are some suggestions that the IDH inhibitors may impact seizure control, and I think that that's data that we're continuing to wait on.  

So I think that there's several outstanding questions there that we will have answers for hopefully in the next several years. I think the big question that we don't have an answer for and that will take a long time to know is whether the addition of vorasidenib in this setting actually improves how long people live. And given how long people with low grade oligodendrogliomas and low grade astrocytomas live today, we probably won't have an answer to that question for more than a decade. 

Brittany Harvey: Definitely. We'll look forward to these ongoing developments and eventually longer term data on overall survival on these agents.  

So, I want to thank you both so much for your work to rapidly include this information from this new trial. And thank you for your time today, Dr. Blakeley and Dr. Mohile. 

Dr. Jaishri Blakeley: Thank you so much. 

Dr. Nimish Mohile: Thank you Brittany. 

Brittany Harvey: And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast. To read the full guideline, go to www.asco.org/neurooncology-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, which is available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode. 

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