Each December, the world of breast oncology comes together for the San Antonio Breast Cancer Symposium (SABCS) — five days of science, education, advocacy, friendship, and some tex-mex if you are lucky. This was the first year the symposium has been back to “normal” after being 100% virtual in 2020, and hybrid with low in-person attendance in 2021. The weather was amazing, the World Cup made for boisterous international gatherings around available televisions, and the atmosphere buzzed as friends and collaborators connected for the first time in 3 years.
In keeping with tradition, I want to share a little with you about some of the science from center stage. But for me, often the best part of SABCS is the meeting behind the meeting. I was able to meet with research collaborators and discuss everything from how to better connect patients to clinical research opportunities, what translational science questions need to be answered so that we can better understand available data to solve future problems, how to communicate scientific change to physicians and patients alike, and to explore pragmatic questions that we still needed scientific answers to. It is in this breast cancer think-tank environment that I draw energy to work harder, and longer and hope to keep going on this quest to end breast cancer.
So now — let’s dive into what we learned this year:
SABCS 2022 was marked by important updates. We saw trial after trial report long-term follow-up studies that confirm we are on the right path.
- Adding abemaciclib (Verzenio®) to the hormonal therapy of hormone-receptor positive Stage II or Stage III breast cancer (with some nuance) decreases the risk of cancer recurrence by about a third.
- For women hoping to become pregnant after breast cancer, taking up to a two-year break from endocrine therapy to allow for conception, childbirth, and a brief interval of breastfeeding followed by re-initiation of endocrine therapy, the POSITIVE trial reported no difference as compared to historical references for breast cancer outcome or outcomes with the pregnancies/babies.
- After a diagnosis of estrogen receptor positive ductal carcinoma in situ (ER+ DCIS), atypical ductal hyperplasia (ADH), or lobular carcinoma in situ (LCIS), ten years of follow up on the TAM-01 trial have shown that patients taking 5 mg of tamoxifen have a significant reduction in the risk of local recurrence or second breast events. This data was presented initially at SABCS in 2018, after which it became incorporated as an option of the American Society of Clinical Oncology Guidelines and the National Comprehensive Cancer Network Guidelines if patients are “unable or unwilling to take the traditional 20 mg dose.” Of note, this “baby tam” dose was not compared to the traditional 20 mg dose, but rather placebo, so we still don’t know if they are truly equal. We do know that after 2018, the 5 mg dose became the most popular dose in the US with a lower discontinuation rate than the 20 mg dose. Bad news? There is no 5 mg tablet — so patients can consider cutting 10 mg tablets in half or taking 10 mg tablets every other day. Lastly, it is important to note this is NOT recommended for patients with invasive (Stage 1 or beyond) breast cancer.
SABCS also included some looks at medications on the near and distant horizons, emerging onto the breast cancer treatment landscape.
- Capivasertib is an AKT/PIK3CA inhibitor that decreased the likelihood metastatic hormone receptor positive breast cancer would progress when used in combination with fulvestrant as compared to fulvestrant alone. However, the treatment was associated with diarrhea and skin rashes
- Elacetrant is an oral SERD that was compared to fulvestrant, an injection, again for metastatic hormone receptor positive breast cancer. The #SABCS22 presentation focused on how sensitivity to elacestrant seemed to relate to how long patients had previously responded to CDK4/6 Inhibitor.
- Camizestrant, another oral SERD, also improved time to metastatic hormone-receptor positive breast cancer progression as compared to fulvestrant. This was also shown for patients with the notoriously hard-to-treat ESR1 mutations.
- Also introduced at SABCS was a whole new class of drugs: PROTAC. PROTAC is a protein that binds a target protein with its partner (E3 Ligase) and then the trimer is tagged for degradation — or gradual elimination from the body. And who wants those old cancer proteins anyway? The PROTAC introduced, ARV-471, showed a promising clinical benefit rate in phase 1 trials.
The last aspect of SABCS was friendly debate. Are all CDK4/6 Inhibitors the same? Should we routinely be clipping lymph nodes prior to neoadjuvant chemotherapy? Is HER2-low breast cancer truly a distinct entity? Personally, I felt the winning side of each of those debates was “no”. There were also panel discussions. How can we better harness big data for health equity? What innovations are needed to improve the process of clinical trials? How can we better train & retain the great minds in medicine?
I hope this long update energizes you as you reflect on the ideas, the progress, and the problems facing the field. I know with certainty that people like us — people passionate about ending breast cancer — are going to be a part of what happens next. I, for one, am glad you are here.