Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline

An interview with Dr. Jaishri Blakeley from Johns Hopkins University School of Medicine in Baltimore, MD, and Dr. Nimish Mohile from the University of Rochester Medical Center in Rochester, NY, co-chairs on "Therapy for Diffuse Astrocytic and Oligodendroglial Tumors in Adults: ASCO-SNO Guideline". This guideline addresses evidence-based therapies for patients with newly diagnosed and recurrent gliomas. Read the full guideline at www.asco.org/neurooncology-guidelines.

TRANSCRIPT

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SPEAKER 1: The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

SPEAKER 2: Hello, and welcome to the ASCO Guidelines Podcast Series, brought to you by the ASCO Podcast Network, a collection of nine programs covering a range of educational and scientific content and offering enriching insight into the world of cancer care. 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 in Baltimore, Maryland, and Dr. Nimish Mohile from the University of Rochester Medical Center in Rochester, New York, co-chairs on therapy for diffuse astrocytic and oligodendroglial tumors in adults American Society of Clinical Oncology and Society for Neuro-Oncology guideline. Thank you for being here, Dr. Blakeley and Dr. Mohile.

SPEAKER 3: Thank you.

SPEAKER 4: Thank you.

SPEAKER 2: First, 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 full conflict of interest information for this guideline panel is available online with a publication of the guideline in the Journal of Clinical Oncology. Dr. Blakeley, do you have any relevant disclosures that are directly related to this guideline topic?

SPEAKER 3: No, I do not.

SPEAKER 2: Thank you. And Dr. Mohile, do you have any relevant disclosures that are related to this guideline topic?

SPEAKER 4: No, I don't have any relevant disclosures.

SPEAKER 2: Great. Thank you. Then let's get into the content of this guideline. So Dr. Mohile, can you start by giving us a general overview of the scope and purpose of this guideline?

SPEAKER 4: Yeah, so over the past 10 years, there have been several positive clinical trials in various glioma subtypes, and several of them have demonstrated a benefit for chemotherapy. The primary purpose of this guideline is to help practicing clinicians understand how these trials might impact treatment for patients with gliomas. During this period, there's also been two updates to the World Health Organization classification of gliomas, and the terminology of gliomas has changed. So what we call tumors today is different from what we might have called them 10 years ago. And so a second purpose of our guideline is essentially to provide a key or a translator so a clinician can look at a pathology report today in 2021 with a current terminology and know what to do with that patient and what treatment best fits for that patient today based on what they would have been called in a trial several years ago.

SPEAKER 2: Great. That makes a lot of sense. So then Dr. Blakeley, looking at this guideline, it addresses four clinical questions, which are after maximal safe surgical resection, what are the evidence-based therapies for adults with newly diagnosed glioma including optimal regimens, settings, and timing of therapy? Then also, what are the appropriate therapies for adults with recurrent glioma, including optimal regimens, settings, and timing of therapy, followed by what should the effect of MGMT promoter methylation status be on choice of therapy and if there are subpopulations that should affect the choice of therapy.

I'd like to review the key recommendations for those clinical questions. In reading through the guideline, the expert panel provided recommendations based on the IDH mutation status and the diagnostic categories in the WHO 2016 and 2021 classification systems for tumors of the central nervous system. So it seems appropriate to review the recommendations in this manner as well. Starting with IDH mutant astrocytic and oligodendroglial tumors, what is recommended for patients with oligodendroglioma, IDH mutant, 1p19q deleted CNS WHO grade 2 or 3?

SPEAKER 3: Absolutely, and I'll just summarize for our listeners to help simplify that as you said, essentially, all of the guidelines are divided along molecular markers. And the first cohort are 1p19q co-deleted gliomas. Something that is a 1p19q deleted gliomas also an oligodendroglioma. Those are interchangeable.

If you are 1p19q co-deleted, you have oligodendroglioma and vise versa. In general, 1p19q co-deleted tumors also are IDH mutant. So you can consider that one bundle. And oligodendroglioma is something that is 1p19q co-deleted and IDH mutant.

And for that whole classification, whether it's WHO grade 2 or WHO grade 3, the recommendation is for radiation followed by the combination of procarbazine, CCNU, and vincristine, based on two prospective studies that showed similar results at different time points. There are a couple of modifications to that guideline. There is a statement that if people feel that the combination of Procarbazine, CCNU, and Vincristine, also called PCV, is too toxic, they can consider temozolomide as an alternative for this subclass of tumors 1p19q co-deleted IDH mutant.

And also, importantly, the 1p19q co-deleted grade 2 gliomas are some of the best performing tumors in terms of prognosis of all glial tumors and maybe all CNS tumors. And so there is a statement in the recommendations that say-- it says it is reasonable to defer therapy under appropriate circumstances. And the text goes into what those appropriate circumstances might be, including how much of a resection could be achieved, what the functional status of the person is, how old they are, et cetera.

But big picture-- 1p19q co-deleted tumor equals an oligodendroglioma, and those are almost all IDH mutant. And the bottom line recommendation is radiation followed by PCV with the parentheses saying temozolomide might be a reasonable alternative to PCV, and if you have a particularly benign presentation with a grade 2 tumor, you can consider deferring that therapy start for a time. The next big bundle is astrocytic tumors that are not 1p19q co-deleted.

So in the guidelines, those are termed as 1p19q non-co-deleted. And those tumors do come in two flavors-- IDH mutant or IDH wild type. And I'm going to focus on the IDH mutant because they track closer to the oligodendroglioma, but they are kind of a bridge between the very good prognosis associated with oligodendrogliomas and the more aggressive prognosis associated with malignant gliomas.

And for this cohort, the 1p19q non-co-deleted IDH mutant cohort, the recommendation is for radiation therapy with adjuvant chemotherapy, and there is data that supports that adjuvant chemotherapy being either PCV or temozolomide. We don't prioritize between those two regimens. And why I'm highlighting the word adjuvant is in some centers, there is a tendency to use temozolomide concurrent with radiation therapy. And the recommendation for these 1p19q non-co-deleted IDH mutant WHO grade 2 tumors is not to use it concurrent but to use it in the adjuvant setting.

And then I will round out with talking about IDH wild type. So now we're, again, 1p19q non-co-deleted but IDH wild type. Those tumors may act closer to the glioblastoma. And in that setting, we would say-- the recommendations say to treat with radiation and consider concurrent temozolomide as you would with glioblastoma or only adjuvant temozolomide as you would with the lower grade astrocytoma.

SPEAKER 2: Great. Thank you for going through that and providing such clarity to those recommendations. Then following that, Dr. Mohile, moving on to glioblastoma and other IDH wild type diffuse glioma, what are the key recommendations for people with newly diagnosed glioblastoma IDH wild type CNS WHO grade 4?

SPEAKER 4: So in the current classification, IDH wild type CNS World Health Organization grade 4 is what we've known of classically as glioblastoma. And for patients with glioblastoma who are fit and can tolerate therapy, we recommend treatment with radiation, concurrent temozolomide, and a six month course of adjuvant temozolomide. We also recommend that they can receive alternating electric field therapy along with the adjuvant temozolomide.

Now the recommendations become a little bit more complicated for patients who might not be as fit-- so patients who might be older, have poor performance status, have other measures of frailty. And the way we wrote this is we said that if a patient who is undergoing a six week course of radiation, if that course of radiation, if the benefits did not outweigh the harm, then you could consider alternate regimens. And these include shorter courses or hypofractionated courses of radiation with or without chemotherapy and also includes courses that are chemotherapy alone.

So in people who have tumors that have MGMT promoter methylation, we can consider the option of temozolomide alone. So this would be specifically for patients who either are older, more frail, who we feel are going to have difficulty going through a radiation course. There is some data to support this temozolomide alone approach.

SPEAKER 2: Thank you. I appreciate you going through those recommendations very clearly as well. You clearly put a lot of effort into these recommendations. So then, Dr. Blakeley, what is recommended for patients with astrocytomas IDH wild type CNS WHO grade 2 or 3?

SPEAKER 3: Yes, thank you. So as Dr. Mohile was just saying, for glioblastoma, you can really think about the recommendations for WHO grade 4 very similarly for IDH wild type independent of grade. And that is a new shift in the management of gliomas in adults. Previously, the histologic grading had a lot of weight on whether or not we would offer radiation and chemotherapy. But with the new prognostic and predictive value known associated with the IDH1 mutation or lack of mutation being IDH wild type, the recommendation is if somebody is IDH wild type CNS WHO grade 2 astrocytoma or grade 2 or grade 3, they would be offered treatment similar to a glioblastoma, which would be concurrent radiation and temozolomide followed by adjuvant temozolomide as long as performance status and all other factors support doing so.

SPEAKER 2: Understood. I appreciate you providing that information as well. So were there additional areas where the expert panel found evidence either insufficient or was unable to make a recommendation?

SPEAKER 4: Yeah, so there's two tumor types where we didn't have enough data to make a specific therapeutic recommendation. The first, unfortunately, is in recurrent glioblastoma. And there were no randomized controlled trials that demonstrated a benefit of one therapy over another. And so our recommendation is that when available, patients should be referred for a clinical trial.

The other area is in a tumor type called diffuse midline glioma. This is a tumor characterized by the h3k27 mutation more commonly seen in children. But we do see this in adults. And here as well, there were no randomized trials that could clearly give us guidance on what the best therapy was even in the newly diagnosed setting. And our recommendation here also was, if available, to be considering a clinical trial.

SPEAKER 2: Understood. It's important to recognize where there are areas where we're lacking evidence as well. So then, Dr. Blakeley, in your view, why is this guideline important and how will it change practice?

SPEAKER 3: Thank you. Well, as Dr. Mohile said at the start, it is quite challenging to review the literature for gliomas in adults because we've had different nomenclature applied across clinical trials and diagnostic studies over the last 10 to 15 years. And this document and these guidelines really seek to be the clearinghouse to help clinicians match up what they see on the pathology report for their patient to the data that is published on phase III studies that has influenced our current standards of care.

So I think the most important way it will change practice is bringing clarity to the data that already exists but has not been accessible to providers trying to help patients make the best decisions for them. It also importantly highlighted how much more work is needed. We desperately need new clinical trials for patients with glioblastoma and patients with astrocytoma IDH wild type 1p19q non-co-deleted WHO grade 2 and 3 and the other areas that Dr. Mohile highlighted. But we're hopeful that this will help provide clarity on both what we do know to help us identify patients who have the best chance of truly meaningful benefit from chemotherapy and where we need to invest more resources.

SPEAKER 2: Absolutely. It seems like this will be a helpful resource for how to treat now and a guide as to what areas of research should be investigated in the future. So in addition to that, Dr. Mohile, finally, how do you view that these guideline recommendations will impact patients?

SPEAKER 4: Yeah, my hope is that this will help standardize our approach to patients with gliomas. In the United States, patients with gliomas get care in all kinds of different settings. And when they're seeing an oncologist, particularly in the community, this might be a very small percentage of the types of cancers that they might be seeing, and it's hard to keep up with all of these trials and hard to keep up with the changes in classification. So our hope is that this guideline helps that oncologist in providing them the clarity, as Dr. Blakeley said, on how to approach treatment here so that all of our patients are getting the best standard of care based on the best available evidence and that they're being considered in those areas where there is not good evidence or referral for clinical trials so that in 10 years, when we put together the next guideline, that we're able to make some progress on some of these questions.

SPEAKER 2: Great. Well, thank you both for all of your work that you did to review the literature and produce these evidence-based recommendations and, as you said, provide a real clear and helpful resource to both clinicians and to improve the quality of care for patients. And thank you for taking the time to speak with me today, Dr. Mohile and Dr. Blakeley.

Finally, thank you to all of our listeners for tuning in to the ASCO Guidelines Podcast Series. 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 available in iTunes 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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