The Advanced Breast Cancer (ABC) 7th International Consensus Conference Guidelines for Advanced Breast Cancer will soon be released. This news organization discussed the new guidelines with Fatima Cardoso, MD, director of the Breast Unit at Champalimaud Clinical Center, Lisbon, Portugal. Dr. Cardoso is president of the ABC Global Alliance and chair of the guidelines committee. The interview has been edited for length and clarity.
Where do the ABC International Consensus Guidelines come from?
The 7th International Consensus Conference for Advanced Breast Cancer was held in November 2023. This is an international conference that takes place every 2 years. At the conference, we discuss new data that have come out in the past 2 years regarding advanced and metastatic breast cancer, and whether they should impact the guidelines or not. We look at whether there is any new treatment that is ready for clinical practice that wasn’t available 2 years ago. We look at whether there is anything else that has changed in the past 2 years.
How do the ABC International Consensus Guidelines differ from other guidelines, such as those from the National Comprehensive Cancer Network (NCCN), American Society of Clinical Oncology (ASCO), or the European Society for Medical Oncology (ESMO)?
Patients and patient advocates are members of the consensus panel where we discuss important issues around this disease and how to manage it. We also do not discuss drugs exclusively because there are other needs for patients with advanced breast cancer, and we issue recommendations regarding the global care of these patients.
Can you tell me about the other issues discussed in the guidelines besides drugs?
For example, in the more general recommendations, we revisited the proper definition of endocrine resistance. A lot of clinical trials are based on selecting a population that is considered to be endocrine sensitive or endocrine resistant, but the definition is very heterogeneous. We have updated the definition because there have been quite a few advances in this particular subtype of cancer. This [new] definition of endocrine resistance and sensitivity will be used and implemented in the different clinical trials, allowing for a better interpretation of the results, with clear impact on clinical practice.
What subtype of metastatic breast cancer had the biggest advances in terms of drugs in the guidelines?
The subtype that had the biggest advances in the new guidelines is the hormonal-dependent breast cancer, the ER-positive, HER2-negative. For that particular subtype, we have new drugs either already approved or in the process of being evaluated. Some of them have been approved in the United States but not yet in Europe by the European Medicines Agency (EMA). We are starting to discuss whether these drugs should be approved, and if they are, how we should use them. It is relevant to know what the cost-effectiveness is of each new treatment, as well and the balance between efficacy and toxicity. Sometimes data are too preliminary and we need longer follow-up or more important endpoints, such as survival.
Elacestrant is one of the drugs that has been approved by the US Food and Drug Administration (FDA), and it is very controversial because the benefit it provides on progression-free survival is modest and we still lack data on survival. So, there was a discussion on whether to consider this drug as an option or wait until we have survival data. The majority on the panel thought we could consider elacestrant as a potential new option, when we do not have other endocrine options available.
We issued a recommendation on a drug that is not FDA approved because we think the FDA is going to approve it quite soon. The drug is capivasertib and it blocks the PIK3CA pathway. [Editor’s note: The drug has since been approved by the FDA.] We have a drug that targets this pathway, alpelisib, but it is quite toxic so it is not widely used. Capivasertib has a better toxicity profile so we believe it could be a good addition to our armamentarium for this particular subtype of breast cancer.
We have lots of new data about the antibody-drug conjugates, the ADCs. Initially, we had more data for HER2-positive and triple-negative disease, but now studies have been done to show the value of the ADCs also in the ER-positive, HER2-negative subtype, and so they are now options. In particular, we have trastuzumab deruxtecan for patients with HER2-low disease. Most of the HER2-low tumors are also hormone receptor–positive.