Dr. Jessica Sukumar and Dr. Dionisia Quiroga discuss advances in adjuvant therapy for patients with early breast cancer and BRCA1/2 mutations, including how to identify patients who should receive genetic testing and the significant survival benefits of olaparib that emerged from the OlympiA trial.

TRANSCRIPT

Dr. Jasmine Sukumar: Hello, I'm Dr. Jasmine Sukumar, your guest host of the ASCO Daily News Podcast today. I'm an assistant professor and breast medical oncologist at the University of Texas MD Anderson Cancer Center. On today's episode, we'll be exploring advances in adjuvant therapy for high-risk early breast cancer in people with BRCA1/2 germline mutations. Joining me for this discussion is Dr. Dionisa Quiroga, an assistant professor and breast medical oncologist at the Ohio State University Comprehensive Cancer Center.

Our full disclosures are available in the transcript of this episode.

Dr. Quiroga, it's great to have you on the podcast. Thanks for being here.

Dr. Dionisia Quiroga: Thank you. Looking forward to discussing this important topic.

Dr. Jasmine Sukumar: Let's start by going over who should be tested for BRCA1/2 genetic mutations. How do you identify patients with breast cancer in your clinic who should be offered BRCA1/2 genetic testing?

Dr. Dionisia Quiroga: So, guidelines on who to offer testing to somewhat differ between organizations at this point. I would say, generally, I do follow our current ASCO-Society of Surgical Oncology (SSO) Guidelines, though. Those guidelines recommend that BRCA1/2 mutation testing be offered to all patients who are diagnosed with breast cancer and are 65 years old or younger. For those that are older than 65 years old, there are additional factors to really take into account to decide on who to recommend testing for. Some of this has to do with personal and family history as well as ancestry. The NCCN also has their own specific guidelines for who to offer testing to. For example, people assigned male at birth; those who are found to have a second breast primary; those who are diagnosed at a young age; and those with significant family history should also be offered BRCA1/2 testing.

I think, very important for our discussion today, ASCO and SSO also made a very important point that all patients who may be eligible for PARP inhibitor therapy should be offered testing. So clearly this includes a large amount of our patient population. In my practice, we often refer to our Cancer Genetics Program. We're fortunate to have many experienced genetic counselors who can complete pre-test and post-test counseling with our patients. However, in settings where this may not be accessible to patients, it can also be appropriate for oncology providers to order the testing and ideally perform some of this counseling as well.

Dr. Jasmine Sukumar: Thank you Dr. Quiroga. Let's next review where we are in current clinical practice guidelines. What current options do we have for adjuvant therapy specific to people with high-risk early breast cancer and BRCA1/2 genetic mutations?

Dr. Dionisia Quiroga: Our current guidelines recommend adjuvant olaparib for one year for individuals with HER2-negative high risk breast cancer. This approval largely came from the data and the results of the OlympiA trial. This was a prospective phase 3, double blind, randomized clinical trial. It enrolled patients who had been diagnosed with HER2-negative early-stage breast cancer who also carried germline pathogenic or likely pathogenic variants of either the BRCA1 and/or BRCA2 genes. The disease also had to be considered high-risk and there were several criteria that had to be evaluated to deem whether or not these patients were high-risk. For example, those who are treated with neoadjuvant chemotherapy, if they had disease that was triple-negative, they needed to have some level of invasive residual disease at time of surgery. Alternatively, if the disease was hormone receptor-positive, they needed to have residual disease and a calculated CPS + EG score of 3 or higher. This scoring system is something that estimates relapse probability on the basis of clinical and pathologic stage, ER status, and histologic grade, and this will give you a score ranging from 0 to 6. In general, the higher the score, the worse the prognosis. This calculator though is available to the public online to allow providers to calculate this risk.

For the subset of patients who received adjuvant chemotherapy, for them to qualify for the OlympiA trial, if they had triple-negative disease, they needed to have a tumor of at least 2 cm or greater and/or have positive lymph nodes for disease. For hormone receptor-positive disease that was treated with adjuvant chemotherapy, they were required to have four or more pathologically confirmed positive lymph nodes at time of surgery. From this specified pool, patients were then randomized 1:1 to get either adjuvant olaparib starting at 300 mg twice a day or a matching placebo twice a day after they had completed surgery, chemotherapy and radiation treatment if needed.

Dr. Jasmine Sukumar: And what were the outcomes of this study?

Dr. Dionisia Quiroga: The study ended up enrolling over 1,800 patients and from these 1,800 patients, 70% had a BRCA1 mutation while 30% had a BRCA2 mutation. About 80% of the patients had triple-negative disease compared to hormone receptor-positive disease. Interestingly, about half of all patients enrolled had received neoadjuvant chemotherapy while the other half received adjuvant chemotherapy.

Looking at the outcomes, this was overall a very positive study. We actually now have outcomes data from a median of about 6 years out. This was just reported in December at the 2024 San Antonio Breast Cancer Symposium. There was found to be a 9.4% absolute difference in six-year invasive disease-free survival favoring the olaparib arm over the placebo arm. What was also interesting is that this was consistent across multiple subgroups of patients and the benefit was really seen whether or not they had hormone receptor-positive or triple-negative disease. The absolute difference in distant disease-free survival was also high at 7.8% and additionally favored olaparib. Most importantly, there was found to be a significant overall survival benefit. The six-year overall survival was 87.5% in the olaparib group compared to 83.2% in the placebo group. This translates to about a 4.4% difference and a relative 28% overall survival benefit in using olaparib.

Now, future follow up is going to be very important. Follow up for this study is actually planned to continue out until June 2029 so we can continue to observe if these survival curves will continue to branch apart as they have so far at each follow up. And I think this is especially important for those patients diagnosed with hormone receptor-positive cancers because we know those patients are at particular risk for later recurrences.

As an additional side note, the researchers also noted that there were fewer primary malignancies in the olaparib group, not just of the breast but also primary ovarian or fallopian tube cancers as well, which is not completely surprising knowing that this drug is also heavily used and beneficial in different types of gynecologic cancers. Ultimately, the amount of adverse events reported have been low with only about 9.9% of patients receiving olaparib needing to discontinue drug due to adverse events, and this is compared to 4.2% reported in the placebo group.

Dr. Jasmine Sukumar: You mentioned that the OlympiA trial showed an overall survival benefit, but interestingly the OlympiAD trial looking at olaparib versus chemotherapy in patients with advanced metastatic HER2-negative breast cancer did not show a significant overall survival benefit. Could you discuss those differences?

Dr. Dionisia Quiroga: I agree, that's a very good point. So OlympiA’s comparator arm was, of course, a placebo. So while this isn't the same as comparing to chemotherapy, it does still potentially suggest that there is a degree of benefit that olaparib can provide when it's introduced in the early local disease setting compared to advanced metastatic disease. I think we need more future trials looking at potential other combinations to see if we can improve the efficacy of PARP inhibitors in the metastatic setting.

Dr. Jasmine Sukumar: For patients who do choose to proceed with use of adjuvant olaparib due to the promising efficacy, what side effects should oncologists counsel their patients about?

Dr. Dionisia Quiroga: The most common notable side effects, I would say with olaparib and other PARP inhibitors are really cytopenias. Gastrointestinal side effects such as nausea and vomiting can occur as well as fatigue. There are some less common but potentially more serious side effects that we should counsel our patients on. This includes pneumonitis. So counseling patients on if they're short of breath or experiencing cough to let their provider know. Venous thromboembo...