Systemic Treatment of Thyroid Cancer Guideline

Dr. Nabil Saba shares the first evidence-based guideline on thyroid cancer from ASCO. He highlights recommendations on first- and subsequent-line systemic treatment – including multikinase inhibitors (MKIs), genomically targeted therapies, immunotherapy, and cytotoxic chemotherapy across four subtypes of thyroid cancer: well-differentiated, differentiated high-grade or poorly differentiated, anaplastic, and medullary thyroid cancer. He dives into the evidence supporting each recommendation and explains the importance of shared decision-making on the risks and benefits of each treatment option. Dr. Saba also touches on outstanding questions including sequencing of agents, addressing resistance, emerging biomarker targets, and management of toxicities. Read the full guideline, "Systemic Treatment of Thyroid Cancer: ASCO Guideline."

TRANSCRIPT

This guideline, clinical tools and resources are available at https://ascopubs.org/topics/asco-guidelines/head-neck-cancer. Read the full text of the guideline and review authors' disclosures of potential conflicts of interest in the 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. Nabil Saba from Emory University, lead author on "Systemic Treatment of Thyroid Cancer: ASCO Guideline." Thank you for being here today, Dr. Saba.

Dr. Nabil Saba: Pleasure to be here.

Brittany Harvey: And then just 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. Saba, who has 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 dive into what we're here today to talk about, Dr. Saba, could you start us off by providing a general overview of the scope and purpose of this first ASCO guideline for thyroid cancer?

Dr. Nabil Saba: So thyroid cancer is a complex disease, and the complexity has been added with the advent of multiple systemic therapeutic agents that have recently come on as part of the standard of care for treating this disease. The guidelines have lagged behind, I believe, in terms of being able to clearly delineate how to use these agents and what clinical settings to use them. And so this guideline, I think, is a much-needed and much-awaited guideline for clinicians to allow them to understand better the use of systemic agents in the treatment of thyroid cancer.

And when we talk about systemic agents, what we want to specify is this applies mostly for patients with recurrent metastatic disease, patients who have failed the standard initial treatment, which continues to be surgical resection for these patients if surgery is possible, in addition to radioiodine therapy for the right clinical setting.

Brittany Harvey: Absolutely. It's a good point that this patient population for this guideline focuses mainly on recurrent disease and patients who have already received surgery and radioactive iodine therapy.

So then this guideline covers four subtypes of thyroid cancer, including well-differentiated, differentiated high-grade or poorly differentiated, anaplastic, and medullary thyroid cancer. As you mentioned, you address clinical questions on systemic therapies, including multikinase inhibitors, genomically targeted therapies, immunotherapy, and cytotoxic chemotherapy in both the first-line and subsequent lines for each of these subtypes. So I'd like to review the key recommendations by subtype.

So first, what are the key points for systemic therapy for well-differentiated thyroid cancer?

Dr. Nabil Saba: It's important to also stress the point that we have these different subtypes of thyroid cancer. So when we talk about radioiodine refractory, those are for patients who are candidates for radioiodine therapy, of course. This usually encompasses the well-differentiated thyroid cancer. So for this group of patients, the guideline focuses on whether the use of multikinase inhibitors compared to placebo or observation impacts the survival in the first-line setting, whether the use of targeted therapies compared to placebo impacts also the survival in the first-line setting, all in the radioiodine refractory setting, of course.

And then we tackle the issue of immunotherapy because this also is a topic that has entered the realm, if you like, of thyroid cancer and is being used in some subtypes of thyroid cancer. So we thought it would be important to raise the question of the role of immunotherapy compared to targeted agents or multikinase inhibitors, in addition to the role of cytotoxic therapy or chemotherapy, as we say, in this patient population. So the guideline goes through all of these questions and then makes specific recommendations as to the use of some of the agents in the first-line setting and second-line setting in case these patients progress after first-line setting.

So, for example, it's clear that for patients who are radioiodine refractory and who have well-differentiated thyroid cancer, multikinase inhibitors are centerpiece of the first-line treatment option. And for this patient population, the recommendation essentially is to use lenvatinib or sorafenib, even though lenvatinib is considered to be the first choice in this patient population in the first-line setting. For the subsequent line settings, patients should be offered cabozantinib, which has been also proven in randomized trials.

As far as genomically targeted therapy, there is always the contention of whether these agents should be initiated first in case the patient has a genomically altered disease. And so, for example, if the patient has a RET alteration or NTRK alteration, the recommendation here is in favor of using RET-targeted therapies such as selpercatinib or NTRK-targeted therapies such as larotrectinib or entrectinib for these patients as a first-line setting. If they do have the BRAF alteration, which is a commonly seen alteration in these settings, the guideline essentially indicates that this may be offered initially prior to treatment with multikinase inhibitors as well, even though the quality of the evidence here is rather lower, and the strength of the recommendation is conditional. And so it's clear that multikinase inhibitors, in the absence of any of these genomic alterations, is really the first line, and then the question becomes when do we use these genomically targeted approaches in patients who have genomically altered disease?

Which basically introduces also the complexity of the question here because we have multiple agents depending on these genomic findings. And then it is sometimes confusing for practitioners which one to use or what do we use first? And so I think the guideline provides clarity in terms of what is acceptable, what is rather not acceptable, what is based on a strong recommendation, what is based on a rather weaker recommendation. I think that's part of the value of such a guideline.

And then finally we have the question of radioiodine well-differentiated and the question of immunotherapy as a first line. And here we do not recommend using immunotherapy for this patient population. For patients with subsequent line settings, potentially adding pembrolizumab to a multikinase inhibitor is mentioned, however the evidence is low, and the strength of the recommendation is also conditional here. As far as chemotherapy, this is not recommended in this day and age for this patient population, however it may be considered also in patients who fail or progress on genomically targeted therapy and/or multikinase inhibitors.

So this is the summary of the recommendations for well-differentiated thyroid cancer, but certainly, for details, I would refer you to the actual guideline since there are many nuances that cannot be covered during just this discussion.

Brittany Harvey: Certainly. The full guideline will be available for listeners in our show notes, and there are many recommendation tables and figures that can help folks as they think through these recommendations. A lot of those key points are really important as clinicians think through which systemic therapies to offer and sequencing of these agents, as you mentioned.

Following those recommendations for well-differentiated thyroid cancer, what are the recommendation highlights for systemic therapy for differentiated high-grade or poorly differentiated thyroid carcinoma?

Dr. Nabil Saba: This entity is rather a rare entity. It's important to stress the fact that this entity has not really been very well represented in clinical trials, and so when we talk about differentiated high-grade or poorly differentiated, the information here is limited. However, the guideline infers on the recommendations to this subtype of thyroid cancer based on what we know for other subtypes. And I think because of the strength of evidence we have in the well-differentiated and the anaplastic thyroid cancer, this guideline for this subgroup of patients draws from these two guidelines and sort of makes recommendations based on this.

So in the first-line setting, of course, if patients don't have a genomically altered disease, we certainly would recommend lenvatinib or sorafenib like we do in the well-differentiated disease. For patients with genomically altered diseases, we follow sort of the same guideline as we have followed for the well-differentiated setting, with the caveat that the quality is rather lower here and the strength of the recommendation is rather conditional for this subtype of patients. And so I think the take-home message is we do have these recommendations similar to the well-differentiated, but the strength of these recommendations for this particular subgroup of thyroid cancer patients is not as strong, given the under-representation in clinical trials. And that's basically the summary of this disease. Same applies to immunotherapy as well as chemotherapy here.

Brittany Harvey: Absolutely. I think it's important to recognize where the evidence is not as strong, it's really important that the guideline panel has still offered up some recommendations to help clinicians in their daily practice as well.

The next subtype the guideline panel addressed, what does the expert panel recommend regarding systemic therapy for anaplastic thyroid cancer?

Dr. Nabil Saba: So it's important to remind the audience that this is a disease with dismal outcome, and this is rather a very, very rare type of thyroid cancer. So the challenge with anaplastic is we've had very little traditionally in terms of options for patients. However, this guideline highlights the advances that have happened in this disease over a relatively short period of time and stresses the important role of systemic agents. And so, for example, for non-genomically mutant anaplastic thyroid cancer in the first-line setting, the guideline does recommend lenvatinib with or without pembrolizumab. Even though the evidence of the quality is low and the strength of the recommendation is conditional, there is enough data that this recommendation could be made. The added complexity for anaplastic thyroid cancer is that this is a disease where multimodal approaches initially are really encouraged as well, including surgical resection primarily, but also potentially thinking about other modalities such as radiation therapy, as these patients have usually very aggressive disease.

And so as far as genomically targeted approaches, the story of targeting BRAF I believe has been a successful story in this disease. And again, for patients with BRAF V600E mutated anaplastic thyroid cancer in the first-line setting, the guideline is clear in saying that we should offer BRAF/MEK inhibitor targeted therapy, namely dabrafenib and trametinib based on published data; the quality is moderate, though the strength of the recommendation is strong, essentially because of the compelling data in these rather small studies. In the first-line setting, again, we may offer also BRAF/MEK inhibition with or without pembrolizumab as well, and the strength here is low, with the recommendation being conditional as well. So you can see here that unlike the other types, immunotherapy may play a bigger role here in this type of cancer compared to the well-differentiated carcinoma because of the nature of the disease, and this has been also stressed in other guidelines.

For patients who progress on genomically targeted therapy, there are not too many options, even though people can revert back to lenvatinib or lenvatinib and pembro. We do recommend participation in clinical trials for these patients because we really don't have any clear-cut options since the strength of these recommendations is conditional for these patients.

As far as the question of immunotherapy per se, we talked about lenvatinib with pembrolizumab. There is also data on ipilimumab and nivolumab. So we include that also as an option for the first-line setting, and we also include, obviously, the dabrafenib and trametinib in combination with pembrolizumab. And even though all these recommendations are conditional, the size of these clinical trials are single-arm phase II studies. In terms of chemotherapy, again, no recommendation in the first-line setting. However, for patients who fail MKI or fail immunotherapy, clinicians may offer cytotoxic chemotherapy. So you can see that in this rare disease, the recommendations already in 2026 indicate a complex tree of decision-making for a number of these cases. And I think this is where these guidelines offer value to many of the practitioners out there.

Certainly, they don't claim to answer any or every possible clinical scenario for these patients because anaplastic thyroid cancer, like any thyroid cancer or any malignancy, usually has to rely on careful evaluation on a case-by-case basis, and for this disease in particular, on a multidisciplinary evaluation based on evaluation by surgical team, by medical oncology, by radiation oncology. But hopefully, these guidelines help at least put in the systemic therapy within that context.

Brittany Harvey: Absolutely. I think this is also where, in the guideline, the clinical interpretation can really be helpful for readers. And as you mentioned, that multidisciplinary collaboration along with shared decision-making with patients on the risks and benefits of each treatment option is really critical here.

So the final subtype that the guideline expert panel addressed, what systemic therapies are recommended for medullary thyroid cancer?

Dr. Nabil Saba: Yes, so medullary thyroid cancer is a separate disease in its own merit, and biologically it's different from the other diseases. And even though it's a relatively rare thyroid cancer, there has been quite substantial advances in systemic therapy, and I think the guideline importantly highlights these advances for this type of thyroid cancer, and this subtype adds to the value of the guideline as well.

For these cancers, targeted therapy for patients who have RET alteration is really recommended as a first line. So for patients who have RET mutant disease, selpercatinib certainly is the treatment of choice, and this is based on high evidence and the recommendation being very strong here because it's based on randomized phase III data. In the subsequent line settings, however, patients with RET-altered disease who have progressed on selpercatinib, unfortunately, we don't have clear-cut recommendations, however, participation in clinical trials is recommended. If a trial is not available, we recommend that patients be offered vandetanib or cabozantinib in this situation.

For patients without the RET alteration, in other words, for patient populations with wild-type disease, the first-line setting should include cabozantinib or vandetanib based also on improved progression-free survival in randomized clinical trial, and here the recommendation is quite strong.

In terms of the role of immunotherapy here, there is very, very little role, and so we don't recommend using immunotherapy in the first-line setting or subsequent line setting. Similarly, for chemotherapy or cytotoxic chemotherapy, it's not recommended that patients be exposed to cytotoxic chemotherapy outside of a clinical trial, whether this be in the first-line setting or second-line setting. We say that in the second-line setting, if patients have failed genomically targeted therapy, clinicians may offer cytotoxic therapy, however, here the evidence is low, and the strength of the recommendation is conditional. And so clearly that tells you that advances have been substantial in this disease, specifically in the realm of targeted therapies, which is importantly highlighted in this guideline as well.

Brittany Harvey: Yes, it's great to see the advances across these different subtypes. So thank you for reviewing all of these recommendations. It's clear you and the panel spent a lot of time reviewing the evidence to craft these recommendations.

So you've already touched on this throughout our conversation already, but I'd like to ask, in your view, Dr. Saba, what is the importance of this guideline, and how will it impact both clinicians and patients with thyroid cancer?

Dr. Nabil Saba: This is a guideline that's important because of the complexity of management of thyroid cancer, in addition to the fact that there has been quite a few systemic therapeutic agents that have come to the scene in the disease, and those are used in specific situations. We talked about medullary thyroid cancer and the story of RET inhibition, for example, the question of sequencing of these agents is important - what do you choose first in terms of your choice depending on the clinical scenario, I think, is highlighted in this guideline. I think this is going to be extremely helpful to practitioners inside and outside the United States because it is going to offer a guide for them to essentially decide on what would be the standard therapeutic option that should be offered to these patients.

I know that many of these agents are not perhaps available in other countries, and I hope this guideline will also raise awareness, since it is coming from ASCO, that these agents need to be explored and considered for a large group of the population that may not have access to them, especially outside the United States and in third-world countries. And so I think from that angle, I think also the guideline is important in that it sets what is the accepted standard in terms of systemic therapy for these patients with these different diseases.

Brittany Harvey: Yes, these evidence-based guidelines certainly set a standard and it will be really important to have these in the hands of many different people to inform best practices for care.

Additionally, you've also mentioned earlier that several of the recommendations referred patients to clinical trials where there wasn't evidence. So I'd like to ask, what are the outstanding questions and ongoing research you are watching in the thyroid cancer space?

Dr. Nabil Saba: This guideline I would like to look at it as a start. This is a much-needed start, however, it also exposes us to the fact that there are so many unanswered questions yet. We still don't know the exact way or best way to sequence these agents. The story of, for example, multikinase inhibitors in well-differentiated thyroid cancers that have BRAF alteration, what is to be started first? Do you start with a multikinase inhibitor, or do you start with a BRAF inhibition? This is a topic of a cooperative group trial currently answering these questions in terms of what is the best sequencing because, you know, you do have the approved cabozantinib in the second line, for example, but you also have the approved BRAF inhibition, which could be done in the first or second line. And so sometimes that is confusing to clinicians for a good reason because no studies have really examined the question of the appropriate sequencing of these agents. And so I think the more we get these agents as available options for treating patients, the more pressing the question would be of what would be the best sequencing. So I think that's a major question to tackle, and hopefully clinical trials will tackle that.

I think the question of resistance to some of these agents, we don't talk too much about that in the guideline, but certainly these agents have limitations. Not every patient who gets a genomically targeted approach is to benefit from that. We've seen many patients who progress on these, and so the question is, how to overcome resistance? Even for the strong data that we have, for example, on RET alteration or NTRK, resistance mechanisms do happen, and we've seen patients who fail larotrectinib and then they need to go on other therapeutic options. And so I think clinical trials are crucial in answering all these questions, in addition to targeting other subtypes of thyroid cancers that have not really been very common. We know that RAS is also seen in some thyroid cancers, HRAS. There have been some studies along that line. ROS is another potential target. And so the question of resistance, I think the question of sequencing, in addition to the question of toxicity. Because, you know, how best to dose these agents? We talked about this a little in the guideline, but again, the focus on this guideline was not too much the toxicity management. So I think management of toxicities should also be a topic of interest that needs to probably accompany any systemic therapy guideline since we're using agents that people may not be too familiar with when they use it for the first time.

Brittany Harvey: Definitely. We'll look forward to the results of these trials that you mentioned to inform sequencing, resistance, new targets, and addressing toxicity and potentially inform updates to this guideline.

So I want to thank you so much for your work to develop this first ASCO guideline for thyroid cancer and for your time today, Dr. Saba.

Dr. Nabil Saba: It's been my pleasure and it's been a pleasure to actually accomplish this and publish this guideline because I do believe it will be of great benefit to the oncologic community.

Brittany Harvey: Absolutely. And finally, 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/head-neck-cancer-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app, 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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