Pre-analytical phase challenges and biomarker testing in HER2+ metastatic breast cancer

high-quality pre-analytical handling of all specimens and the ones the interpretation are essential. Recent development of powerful new drugs, for example, to hurt you antibody drug conjugates, has shown efficiencies in tumour that are hurt to low or even out to low. This podcast is for healthcare professionals only and is supported by an independent educational grant from Daichi Sankyo. Hello and welcome back to the Eumkology Brothers podcast. I'm Rohit Guesa, a practicing community medical oncologist. Here with my brother and co-host, Rahul Guesain, another community medical oncologist. Well, with our mission of oncology brother, it has truly been about bridging the gap between academic research and community practice. And today, the topic at hand we'll be tackling is her two testing in breast cancer space. What used to be rather binary classification that is positive or negative has rather evolved into significantly something more profound. That is what we are using for her two status being reported as positive and negative. Now we are also reporting that as positive or low or even ultra low. It is important to appreciate the shift and these nuances in testing because her two has now become not just a classic oncogenic driver, but also a target for antibody drug conjugates, such as chestism, aderix, T-can. To help us unpack all this, we're joined by two excellent guests, Professor Gary C., a pathologist from Chinese University of Hong Kong, and Dr. Carlos Barrios, a medical oncologist from Brazil. Gary, Carlos, welcome. Thank you. Thank you. Before we talk about testing itself, Carlos, could you start us off here? Why biomarker testing is rather important, particularly for her two? So how does this play in metastatic breast cancer space today? I think that we need to recognize that over the last 20, 25 years oncology has changed significantly. We have come to recognize that the biology of the disease is much more complex than we usually recognize before. It is obviously heterogeneous, okay, very complex. And besides the complexity of a single tumor, it's very important also to recognize at the same time that disease changes, as evolves. A number of different new biomarkers have emerged. Piatric kinase mutations, years are one mutations, BRCA, PDL1. Besides, they're very important her two modifications that you have mentioned in the introduction. So essentially, the importance of this biomarker is that they do have a significant impact in the way we manage patients and we select treatment. Thank you so much for getting us started. Again, coming back to that clinical implication, we do need to appreciate that her two status as we have treatment options based on this. Gary, with that background, can we start off with some basics? How do we first define her two in her clinical practice today? Her two-hour human epidemoglobulin factor is up to two. She's expressed in 15 to 20 percent of breast cancers, and they are very aggressive, but they respond well to targeted therapies. So it is crucial to test for her two expression in breast cancer. We can look for the gene amplification by doing incitement hybridization. This is very accurate, but it's more expensive and takes longer. In a clinical setting, it's not very easy or quick to do for a lot of patients. The other way to do is to look at her two protein expression by immunofitus history chemistry. So by looking at this, we score the tumor's expression from 0 to 3 plus. 0 is no staining or very, very weak staining. One plus is weak, two plus is moderate, and three plus is strong. Only three plus strong staining correlates with gene amplification, and thus considered positive. The rest of the cases are considered her two negative, even though they do have some staining. So this includes score 1 plus or 2 plus, and now they are called her two low. And for cases that are scored 0, but they show very, very weak staining, because it's her two ultra low. Previously, there are only drugs that are effective as her two positive cancers. Recent development of powerful new drugs, for example, to her two antibody drug conjugates, has shown efficacies in tumor that are her two low or even ultra low. So this is very crucial for us to be able to accurately evaluate her two for allowing optimal patient's treatment option. However, there are a lot of practical challenges in her two evaluation, particularly at this low end of the spectrum. heterogeneity, as Carlos just alluded to, in her two expressions, either within the tumor itself, or between multi-whole or different tumor foci in a metastatic setting is a real issue, and that happens very frequently. So this is very significant, and it has a lot of problems for us in testing her two for our patients. Carlos, given this testing with the her two low, ultra low in our hormone receptor positive, this is essentially making 85% of our patients. In terms of her available therapies, you've been involved closely in these clinical trials. Can you briefly touch on what we've learned from Destiny Bresil 6, because that is what today is approved? As an introduction to that question, and thank you for that. I think for the community oncologist, it's extremely important to recognize that traditional anti-hereto-therapy works for her two three plus, the her two positive disease. And the major change in her two evaluation of this biomarker evaluation that we have seen is that instead of a positive to a negative result for the test, we have a continuous expression which changes significantly the way we need to approach the results. Because some of the new therapies, as you mentioned, for example, in the DB06 trial, also work in patients that are not her two three plus. They also work in one plus and two plus and in the ultra low as Gary mentioned. So this concept of moving from a binary result positive or negative is extremely important for the community oncology to learn that we are changing. There is therapy that works also in patients that have lower expressions of her two. Thanks so much for covering that Carlos. But where do we stand today is, which is again exciting times where we have TDXD now approved for that low and ultra low metastatic hormone receptor positive disease, but coming back to testing and some challenges that we tackle here. We run into this in our clinical practice often. Gary, you talked a bit about the heterogeneity, but where do you see most commonly some of the pre-analytical challenges that arise in metastatic breast cancer space? Well, there are multiple issues in this setting. The first problem is vector-cellic diseases. Perhaps these are always taken from distant sites, multiple sites, bone liver, lymph nodes, and many of these are very difficult to assess. So unlike the primary tumor, which is much easier to assess. So there are only limited materials can only be found or can be taken from the patient. So this will limit the materials that we were able to perform our tests. Secondly, very often in this juncture, our oncologist would like to do, as Carlos has mentioned, not only to, but a whole bunch of other tests that would be targetable by different types of therapies. So for example, PDA1, ERPL, mutations, ESR1, etc. Every test we're fighting for specimens for these tests to be performed. So we need to have a very clear mind and clear pathway to how to only quote our precious sample for power-etizing the test to be done. Thirdly, very often in ER positive cancers, when the metastasis are recurred many years afterwards, these metastatic sites very commonly are in the bone. And we know about seeing bone samples are very difficult because bone is very hard and it's not amenable to normal histologic processing. We need to decalcify the bone. So we would use acid or materials to, or chemicals to dissolve the calcium. And with this, we may partially destroy the antigens in the tumor cells. First, that would also jeopardize the accuracy of the testing for immunities of chemistry. Can you touch on some clinical pearls or best practices recommendations to overcome these pre-analytical challenges, especially around specimen selection, fixation, decalcification, and handling that tissue and metastatic settings? In clinical practice, of course, we always try to obtain tissue from the most accessible or adequately preserved specimens. Once the specimens obtained, there are specific things that we need to do and to observe. The first is to avoid delay in fixation. There often as soon as we get the specimen we should fix them so that the protein would not be denatured. And this is called cold ischemic time and we would like to keep the cold ischemic time as short as possible and certainly less than an hour. This may help to preserve the heretoedigen so that they can be detected even at low level. Secondly, the use of fixative and duration for the fixation. In most pathology left, the recommended or standard choices are 10% neutral buffer to formulae and the recommended fixation time is between 6 to 72 hours and the maximum of 96 hours is recommended. So ideally hereto should be assessed within this framework. Thirdly, when we prepare a slice for staining we should use freshly or recently cut slice from a pyrofen block. I guess we should show that sections that have been cut for more than a few weeks which shows reduced antigenacity. So this sensitivity will be lower and our low hereto low will become hereto negative probably. And for bone specimens, one of the better way to deal with bone specimens when we have to obtain a mectastelic biopsy will be to separate the soft tissue adjacent to the bone from the bone itself. So we can process the soft tissue in a routine manner. Hopefully there's good preservation of the antigenacity. And in a bone specimen, we try to use medita rather than acid to better preserve the proteins within the tumor cells. So overall, pre-analytical errors usually would lead to reduction of the antigen expression and plus it would lead to fast negative results rather than fast positive results. So this is particularly important in hereto low ultra-low setting because when they are already very low, if you lost your sensitivity then it will become decreased from ultra-low to negative. And again, that would change the treatment protocol for our patients. If you have multiple metastatic disease site that is larger bone lesion and even long findings where you did go for larger bone lesion because it was rather easily accessible. But you got completely hereto zero or no expression at all. In that particular case, do you want to chase for that lung lesion because of the heterogeneity of the disease that you may find that less than 10% in staining here where TDXD might be applicable? Not necessarily. It's obviously important to review that biopsy to make sure the pathologist actually when they said it was hereto zero, to make sure that they are using the correct assessment because this has changed not only for the clinician but also for the way the pathologist is evaluating the biopsy. So it needs an adjustment both from the clinical and from the pathology point of view in order to make a correct diagnosis for a correct treatment selection. I agree with Carlos. I remember years ago the criteria for hereto positivity has been switched multiple times over the past 10 years from 10% to 30% to 10% etc. So I think with the change of the treatment protocol and paradigm, it's always good to review particularly using the O definition when we diagnose the orscore to hereto. Carlos, very good part. And again here retesting and chasing that right tissue is ideal. Gary, can you touch a little more on the testing aspect? I know we talked about IAC and IAC. What about NGS? What about liquid biopsy? Because now we also potentially have ERBB2 mutation. Can you touch a little on this comparing IAC IAC and the role of NGS here? The IAC and IAC are the routine pillars that we are doing day in day out in most laboratories of pathology. There are emerging two such as for example liquid biopsy or Dixgen sequencing. NGS is very powerful and is looking at the entire genome of the tumors. So it's not only looking for hereto amplifications but other changes like hereto mutations or other the genomic changes in the broader context. And it's also more sensitive because it amplifies all the genomes. So it can help us to detect more changes and hopefully many of this would be targetable. The other thing that I've just mentioned is liquid biopsy. You're only taking blood from the patient and it is convenient, it's non-invasive and it also has a very good advantage over the other tissue biopsies because in the patients with multiple sites of tumor metastases each individual metastatic focus may have different generic changes. So there's no way that we can assess all the individual foes I by doing tissue assessment and rather it is much easier to look for the CTDNA in the blood because that would represent basically a malgamation of all these tumor metastatic sites. So we would have a very clear overall picture of the genomic landscape of the metastatic diseases the patient had. However because of these tests are very sensitive and very dependent on good sample quality. So this is very important that we would be very very careful when we take the samples and prevent contamination. All testing is one thing or one puzzle but making sense of this reporting is another aspect. Carlos, how challenging it is to interpret these results in clinical practice and how do you handle that in particular scenario borderline or equivocal cases. One of the questions I ask myself whenever I receive a pathology report is does this pathology report actually speaks to the clinical picture this patient is presenting or not because from that moment on everything I do it's going to be based on that piece of paper because this will have a absolutely fundamental influence in whatever happens afterwards. So I think that these questions from the clinical point of view for a community oncologist is are absolutely critical to consider. Thank you for touching on this because getting that right diagnosis, communication, all this essentially in the bigger scheme of things is part of multi-D. Gary, today how can pathologists take a little more proactive role with multi-D settings to ensure that testing, interpretation and communications are optimized for these metastatic disease cases. We play a very important and active role increasingly in MDTs in the setting of patient management. As we all know now, managing oncological patients is a very very complex multidisciplinary collaboration. We can highlight sample limitations and potential errors. All tests would have some inherent errors and it's very important to recognize there are things that are unavoidable elements of uncertainty is that it's better to be made known to the management team. We could also bring to our colleagues the possibility of issues related to H2 heterogeneity and the subtleties of low level expression. So this would explain how the results come about and how to interpret the results and it's probably best for us to be there for eucrophocal or difficult or results that doesn't really tie in with the clinical scenarios. Oh, thank you so much for touching on that, Gary. With regards to multi-disciplinary approach, Carlos, from your perspective as a treating medical oncologist, how does that multidisciplinary tumor work collaboration looks like when you're managing her two positive breast cancer patients across multiple lines of therapy and also repeatedly reassessing the biomarker itself? Those concepts are extremely important. Multidisciplinary care is not necessarily mean a meeting on a Friday afternoon on the fourth floor where everybody goes. Okay? This can be feasible in an institution, a tertiary institution where everybody works at the same place. Okay? Community oncologists in the US, community oncologists in other parts of the world are completely different. Probably the best multidisciplinary approach is a phone call where you're going to discuss this with the pathologists, with the radiation therapies, with the surgeon. It's not necessarily the same thing as a multidisciplinary meeting where everybody gets together in the same room. Okay? It doesn't help to tell a community oncologist that you need to discuss every single case in a multidisciplinary meeting where everybody is to get, so answering your questions specifically, I think that discussing these things with another colleague, trying to build the best possible recommendation for a single case, identifying the biomarkers or the two more characteristics that could be important influencing treatment selection, prognosis, I think that those are the important aspects. Donkology is becoming so complex, okay? That we cannot manage this kind of disease without help and without discussing this with other people. - Carlaus, that is very, very, very important. Again, because the change that we're seeing in the world of cancer is fast, it is complex. Multideas important, but this looks different in every science. Before we wrap up, we'd love to leave our listeners with some clinical key takeaways. Gary, starting with you, what are your clinical takeaways from today's discussion? - From the pathological perspective, accurate assessment of biomarkers is very important and it's increasingly difficult because we are getting closer to closer to the thresholds. There are many variables that would affect the outcome of the results of biomarker testing. High quality pre-analytical handling of our specimens and the ones to interpretation are essential. So talk to your pathologist. - We could not agree more, Carlos. Your clinical takeaways from the discussion today. So I think that the critical key message is that we need to recognize this complexity, the understanding of the disease, the resistant mechanisms, actually leads to one very important concept. We improve patient outcomes. We need to embrace the way of discussing this with different sub-specialties. It's not only the pathologist, it is the radiologist, the interventional radiologist, the surgeon, the radiation therapies, et cetera, et cetera. I think that cancer requires obviously a multidisciplinary, and it is a multidisciplinary effort. - Why if you're doing this is all because there is meaning to it because there are clinical implications tied to it. Gary and Carlos, thanks so much for both of your insights today and this discussion, where we are highlighting how far her two testing has come, along from binary readout to more nuanced decision today, that is her two low, her two ultra low, and how all of it translates in our clinical practice to give our patients more treatment options. Well, thanks for tuning in. Make sure to follow us along for more conference highlights, improve world and treatment algorithms. We are the oncology brothers. - If you enjoyed this podcast and want to find out more, then please look for the oncology medical conversation podcast under the account of Core2Add Medical Education. Also, don't forget to rate this podcast, subscribe to our channel and share it with your colleagues. Thank you for listening and see you next time. This podcast is an initiative of Core2Add and developed by Precision Oncology Connect, a group of international experts working in the field of Precision Oncology. The views expressed are the personal opinions of the experts and they do not necessarily represent the views of the experts organization or the rest of the Precision Oncology Connect group. For expert disclosures on any conflict of interest, please visit the Core2Add website. (gentle music)