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, platinum