Systemic Therapy for Metastatic Breast Cancer

Dr. Banu Arun and Dr. Sana Al Sukhun share recommendations from the newest ASCO resource-stratified guideline on systemic treatment for patients with metastatic breast cancer. They describe the importance of this new guideline, the four-tier resource setting approach, key recommendations, and implementation considerations. Recommendations are discussed for systemic therapy for HER2-positive, triple-negative, and hormone receptor-positive metastatic breast cancer, across Basic, Limited, and Enhanced resource settings. Drs. Arun and Al Sukhun highlight the importance of this guideline for clinicians and patients in regions with limited resources to optimize cancer care.

Read the full guideline “Systemic Treatment of Patients with Metastatic Breast Cancer: ASCO Resource-Stratified Guideline” at www.asco.org/resource-stratified-guidelines."

TRANSCRIPT

This guideline, clinical tools, and resources are available at http://www.asco.org/resource-stratified-guidelines. Read the full text of the guideline and review authors’ disclosures of potential conflicts of interest disclosures in the JCO Global Oncology, https://ascopubs.org/doi/10.1200/GO.23.00285 

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. Banu Arun from the University of Texas MD Anderson Cancer Center in Houston, Texas, and Dr. Sana Al Sukhun from Al Hayat Oncology Practice in Amman, Jordan, co-chairs on “Systemic Treatment of Patients with Metastatic Breast Cancer: ASCO Resource-Stratified Guideline.” 

Thank you for being here, Dr. Arun and Dr. Al Sukhun.

Dr. Banu Arun: Thank you for having us. 

Dr. Sana Al Sukhun: Thank you. Pleasure to join you.

Brittany Harvey: And before we discuss this guideline, I'd just 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 the guests who have joined us today on this episode, are available online with the publication of the guideline in the JCO Global Oncology, which is linked in the show notes.  

Then, to jump into the content of this guideline, Dr. Al Sukhun, can you first provide an overview of the scope and the purpose of this guideline? 

Dr. Sana Al Sukhun: Sure. And again, thank you, Brittany. Pleasure to join you. This guideline is really interesting and very important. It addresses the care and treatment of the most common cancer worldwide, particularly metastatic breast cancer, taking into consideration different availability of resources, particularly in countries with limited resources. As you know, most of us are aware of the importance of clinical practice guidelines improving outcomes for patients in medicine, not only in oncology, but most of those guidelines are developed in countries that are highly resourced. So their applicability in countries of limited resources that lack infrastructure and resources is definitely limited because they cannot really adopt and adapt to those guidelines, which makes resource adapted or resource stratified guidelines quite important and helpful. First, to clinicians caring for patients so that they can properly allocate resources, prioritize how to use therapy for patients, but also even policymakers to allocate resources and plan graduated implementation of science to improve outcomes for their patients according to the progressive availability of resources. 

So we're talking about breast cancer, the most common cancer worldwide. And not only is it the most common cancer worldwide, but also more than two-thirds of new cases are diagnosed in countries of limited resources. Unfortunately, they also carry the burden of more than 70% of the mortality attributed to breast cancer. Another challenge is that the median age for the patients affected with breast cancer in countries of limited resources is indeed at least a decade younger than Western societies, which adds to the burden, not only the social, but also the economic burden of cancer. And unfortunately, presentation in these countries is mostly locally advanced, metastatic breast cancer, therefore comes the focus on helping our colleagues in countries of limited resources to care for patients according to the resources available, not only in countries of limited resources, even colleagues practicing in less fortunate areas within countries that are highly resourced.

Brittany Harvey: Excellent. Thank you for providing that background information for this guideline. 

So then you've just described how many countries and areas have different resources. So, Dr. Arun, could you describe the four-tier resource setting approach that this expert panel used?

Dr. Banu Arun: Yeah, Brittany, that's a good question. I think it's important to know where we started and what infrastructure we used. So for developing resource stratified guidelines, ASCO has adopted its framework from the four-tier resource setting approach, which was actually developed by the Breast Health Global Initiative, and we employed modifications to that framework based on the disease control priorities. What this framework emphasizes is also that variations can be present not only between countries, but actually within countries with disparities, for example, differences between rural and urban areas within one country.  

So the four settings are obviously basic, limited, enhanced, and maximal settings. The basic setting includes core resources or fundamental services that are really absolutely necessary for any public health, primary health care system to function at all. These include services that are typically applied in a single clinical interaction. For example, vaccination is feasible for highest need populations.  

The next tier would be the limited setting. That includes countries or settings with second-tier resources or services that are intended to produce major improvements in outcomes, such as incidences and cost effectiveness. Unlike the basic setting, it can involve single or multiple interactions with providers or healthcare services.

Then the third tier is the enhanced setting, where the services are optional but important, and these services should ideally produce further improvements in outcome and increase the number of quality of options and also individual choices, maybe countries having the ability to track patients and links to registries. 

And then the last one is of course, the maximal setting that includes high-level, state-of-art resources and services that are available in some high-resource countries.

Brittany Harvey: Thank you for describing that framework and the approach that the panel used.

So then I'd like to move on and talk about the key high-level recommendations of this guideline for systemic therapy for metastatic breast cancer across those three lower tiered resource settings - the basic, limited, and enhanced resource settings. So, Dr. Al Sukhun, could you start with the recommendations across these settings focusing on HER2-positive breast cancer? 

Dr. Sana Al Sukhun: Sure. You know, HER2-positive metastatic breast cancer is one of the most aggressive subtypes of breast cancer. However, its outcome has been transformed with the introduction of HER2-targeted therapy. So, apart from patients who suffer from congestive heart failure or limited compromised ejection fraction, which can be evaluated on a case-by-case basis, patients are candidates for HER2 targeted therapy. When we made the recommendations according to the availability of resources, we started in a gradual approach. So, in a maximal setting, you treat patients with HER2-positive metastatic breast cancer in the frontline setting using the combination of trastuzumab, pertuzumab, and taxanes or endocrine therapy if patients have limited disease burden, or if they have the recurrence after a long disease-free interval. Usually, the combination of trastuzumab and pertuzumab with taxane is used. But then again, clinicians can use navelbine, considering good data from the HERNATA trial about its efficacy as compared to taxanes and even also, we recommended platinum therapy according to availability.  

However, if pertuzumab is not available, you go to the next level where we recommend offering, again, chemotherapy, be it taxane, navelbine, platinum, with trastuzumab, or even without trastuzumab if trastuzumab is not available. So, something to keep in mind, chemotherapy is not without efficacy in this aggressive subtype. It is not as good as when you use the combination with HER2-targeted therapy, but it still works. Patients and clinicians in this era of biologic therapy immunotherapy tend to think only pricey medications are the ones that can be used for treatment and improving outcome. However, definitely adding help with targeted therapy is great whenever it's available. But if it's not available, chemotherapy still could be used in a sequential manner. We listed all possible chemotherapeutic options starting with taxanes, navelbine, platinums, even CMF, capecitabine.  

When it comes to second-line therapy, including those patients who relapse within 12 months of adjuvant therapy, the optimal line of treatment would be trastuzumab deruxtecan. However, if it's not available, we recommend to be offered with successive or progressive preference, if it's not available, T-DM1 could be used. If it's not available, capecitabine and lapatinib could be used. If it's not available, trastuzumab with chemotherapy could be used. If it's not available, we go back to the sequential use of chemotherapy, including adriamycin, taxanes, platinums, capecitabine, or even CMF. 

Brittany Harvey: I appreciate you reviewing those recommendations for HER2-positive breast cancer. 

So then, moving along, Dr. Arun, what are the recommendations for patients with metastatic triple-negative breast cancer?

Dr. Banu Arun: Thank you, Brittany. Triple-negative breast cancer, of course, is one of the serious subgroups of breast cancer. About 10 to 15% of patients have triple-negative breast cancer. What I will do is I will divide it into the three-tier settings as well as first-, second-, and third-line therapies. 

For patients with triple-negative PD-L-negative metastatic breast cancer in the limited settings and even enhanced settings, single-agent chemotherapy rather than combination chemotherapy should be recommended as the first-line. However, if patients are symptomatic or have immediate life-threatening disease, combination chemotherapy can be offered. 

For patients with triple-negative breast cancer that are PD-L1 positive, they may be offered in addition to chemotherapy, an immune checkpoint inhibitor, as first-line therapy, most probably in enhanced settings and in basic and limited, of course, chemotherapy. When you move on to the second-line for metastatic breast cancer in patients with or without previous PD-L1 checkpoint inhibitors, clinicians can offer palliative or best supportive care in the basic setting. In the limited setting, chemotherapy with anthracyclines, taxanes, platinums are options. And in the enhanced setting if sacituzumab govitecan is not available, chemotherapy would be an option.

Now, when we move on to the third-line setting for triple-negative breast cancer, clinicians can actually offer chemotherapy and/or palliative care, depending really on the status of the patient.

Brittany Harvey: Excellent. Thank you for providing those recommendations for triple-negative breast cancer. As you mentioned, it's one of the rarer forms of breast cancer. So then, Dr. Al Sukhun, I'd like to move into the last section of patients, actually the most common, but hormone receptor-positive breast cancer. What are those recommendations? 

Dr. Sana Al Sukhun: Thank you, Brittany. As you mentioned, it's the most common subtype worldwide. The rule of the thumb is sequential hormonal therapy, depending on availability. So, whatever you have hormonal therapy, sequential hormonal therapy unless pending visceral crisis or symptomatic disease, it's recommended that you offer sequential single-agent chemotherapy, unless it's a real visceral crisis, where we recommend combination chemotherapy. That's a classic in all our guidelines. 

When considering frontline hormonal therapy, again, I will start from the maximal level and gradually recommend according to availability. So in enhanced levels in many countries now, we have generic CDK4/6 inhibitors, which increase their availability. So we do recommend hormonal therapy with CDK4/6 inhibitors. Upon progression or when they are not available, on progression, you move to the second line of hormonal therapy. If you have liquid biopsy, check for PIK3CA mutation. Sometimes you do have the liquid biopsy, but you do not have alpelisib to offer to your patients with hormonal therapy, then it's okay, you still can move to second-line fulvestrant with everolimus. Sequentially, you can move forward to fulvestrant by itself if you do not have everolimus. And even you can sequence tamoxifen until your patient stops responding to hormonal therapy then you can offer sequential single-agent chemotherapy. 

Brittany Harvey: Thank you, Dr. Al Sukhun for providing those recommendations. 

So then, Dr. Arun, what should clinicians do when we do not have access to receptor assessment? What is recommended for best practices for management of those patients?

Dr. Banu Arun: So, Brittany, that's an important question. There are some basic settings where unfortunately, immunohistochemistry for ER/PR HER2neu determination is not available. Our group really recommends in these cases that clinicians may presume hormonal receptor positivity and offer tamoxifen in most cases. It is expected that IHC would be available in limited and, of course, enhanced settings.

Brittany Harvey: Great. Thank you for providing that information. 

So further, what else should clinicians know as they implement these recommendations, Dr. Arun? 

Dr. Banu Arun: It's very important that we, all healthcare provider clinicians, really know the data. I think reading the guidelines or knowing about first and second line therapies is obviously important, but the devil is in the details. And I think knowing the publications and subgroup analyses, if needed, because every patient is different and sometimes the recommendations cannot go by the books. You really need to do an assessment of the patient and see in which setting you are and then make the most of the guidelines that are recommended. It's to guide. The name is guidelines. It's to guide. And ultimately, it's the clinician's responsibility to find the best available therapy for the patient. And sometimes that includes no treatment and supportive care.

Dr. Sana Al Sukhun: Totally agree with Dr. Arun. They are there to support the clinician decision. After all, the clinician is the one who sees the patient, who can evaluate the patient from all aspects — social aspect, physical aspect, the tumor aspect. So it's not just about the tumor, it's about the patient and the environment where the clinician is treating the patient. However, I believe there is support to the clinician not only in treating the patient, but also on addressing priorities for research to improve outcomes for patients in different resource settings. There is also support for the clinicians to help them advocate for improving care for patients in a strategic way, where they prioritize resource allocation. So they are there to support the clinician at all levels, not only when treating patients, but when advocating for patients, when helping patients to make decisions, when they're discussing with their health officials and policymakers.  

Brittany Harvey: Absolutely. Those are excellent points that you both made about individualizing patient care for the specific person in front of you. So then, finally, Dr. Al Sukhun, how will these guideline recommendations impact patients with metastatic breast cancer globally? 

Dr. Sana Al Sukhun: The ultimate goal for anything we do, including guidelines, is to improve outcomes for patients worldwide. They are there to support clinician decisions, empower clinicians to optimize care for their patients, to advocate for improving outcomes for patients by strategically allocating resources according to the most impactful strategy. They help clinicians to identify areas for research that are needed according to the resources available to them. They are there to guide policymakers, again, also implementing strategies to implement science that could improve outcomes in an efficient way for their societies. So hopefully, all these, with our research, with our advocacy, with our health policy, with our treatment decisions, hopefully all these will improve outcomes for breast cancer patients and ultimately reduce mortality, particularly in less fortunate, limited resource settings for patients everywhere.

Brittany Harvey: Absolutely. We hope that these guidelines improve outcomes and quality of life for patients worldwide. 

So I want to thank you both so much for your work to develop this guideline. There's certainly a large amount of recommendations, so I encourage our listeners to read the full guideline, which is linked in the show notes. And I want to thank you so much for your time today, Dr. Al Sukhun and Dr. Arun.

Dr. Sana Al Sukhun: Thank you for having us.

Dr. Banu Arun: Thank you, Brittany.

Brittany Harvey: And thank you to all of our listeners for tuning into the ASCO Guidelines podcast. To read the full guideline, go to www.asco.org/resource-stratified-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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