The latest in breast cancer research from the San Antonio Breast Cancer Symposium

Every December, thousands of breast cancer researchers and doctors from over 90 countries gather for a five-day symposium in San Antonio, Texas. It’s an important conference for researchers who work in breast cancer, as it provides the latest research information from around the world.

Dr Nick Zdenkowski, an Australian medical oncologist and Medical Advisor to Breast Cancer Trials (a group of leading breast cancer researchers in Australia and New Zealand), attended the 2018 conference and provided a summary for Breast Cancer Trials. They have very kindly allowed us to reproduce parts of it here. For more information, visit the Breast Cancer Trials website.

HER-2 positive breast cancer

The phase three KATHERINE clinical trial investigated whether using the drug T-DM1 (Kadcyla) instead of trastuzumab (Herceptin) provides better outcomes for women who have cancer remaining in their breast tissue after neoadjuvant (before surgery) treatment.

Dr Zdenkowski said the results garnered a lot of interest from those in attendance.

“The trial included patients with HER2-positive breast cancer who received neoadjuvant chemotherapy and Herceptin, followed by surgery to remove the part of the breast that was affected by cancer. Some of these patients have a complete response, which means the treatment gets rid of all the cancer. They’ve got a really good prognosis. But for patients who don’t have a complete response, their prognosis is actually not very good.”

“What this trial did was randomly allocate patients to receive either ongoing Herceptin, which is the current standard of care, or Kadcyla, a new HER2 treatment that we currently use for metastatic HER2-positive breast cancer.”

Dr Zdenkowski said the results were very promising.

“They found patients who received Kadcyla were less likely to experience a recurrence of their breast cancer in the future. There was a substantial and clinically important difference in the relapse rate; the risk of developing an invasive recurrence of the cancer, or of death, was reduced by 50 per cent. It’s something that, for a poor prognosis patient group, is really good to see.”

Many American-based oncologists said they would immediately implement it in the clinic, Dr Zdenkowski said. However Australians will have to wait.

“In Australia, we need TGA approval to use drugs in a new or different way. We also need Kadcyla listed on the PBS for this purpose, because it is an expensive drug and not affordable for the majority of patients. Hopefully the drug company that makes the drug will submit the applications and it will come.”

De-escalation

Discussion and trials involving de-escalation (providing less treatment than the current standard treatment while maintaining good outcomes) have been occurring in Australia and New Zealand for quite some time. Dr Zdenkowski said it was good to see it was a large focus at the symposium.

“It was really interesting, because the US is a classic escalation situation. They always want to do more and more. We’ve got de-escalation trials running in Australia, such as EXPERT, so it was quite useful to see that it’s breaking into the US market.”

The EXPERT trial is investigating whether some women with low-risk early breast cancers can avoid having radiotherapy after surgery without affecting their risk of the cancer recurring.

Dr Zdenkowski said a session on de-escalation, presented as a debate between internationally renowned breast cancer specialists, was particularly interesting.

“Debates can be difficult in medicine because there are always shades of grey. The conclusion was that there are some patients who need more treatment, like those in the KATHERINE study, and there are some who need less, and we need to work out which patients they are.”

Dr Zdenkowski said the most difficult part of implementing de-escalation into treatment is communicating it to patients.

“Doing less is not something that patients take on that easily and medical oncologists probably need to think about how to talk to patients about less treatment actually being better for them.”

Quality of life

Not all breast cancer research is focused on finding new treatments. Some researchers build on already existing treatments and prevention strategies to allow for a better quality of life through treatment and the years following. A number of quality of life researchers presented findings at San Antonio.

“There was a report about the quality of life benefits from breast conserving surgery. It showed that women who have a lumpectomy have a better quality of life than those who have a mastectomy – because there is still some symmetry in the breasts, and women don’t need to think about having breast reconstruction later on.”

Another interesting quality of life study was a potential new treatment for hot flushes.

“Women who have the most common type of breast cancer, hormone receptor-positive breast cancer, almost always end up on hormone blocking treatment and those treatments can cause menopausal symptoms, hot flushes being the most significant one”, Dr Zdenkowski said.

“Hot flushes cause all sorts of secondary side effects, such as breaks in concentration, sleep disturbance and worries about social events. Alcohol can sometimes set them off, as can coffee, tea, chocolate and stress. Some women don’t want to go out in summer or out in public at all, and that sometimes leads to women stopping hormone blocking treatments, meaning their breast cancer is more likely to come back.”

“This research investigated a drug called oxybutynin, which is used for problems with an overactive bladder, but also has potential to reduce hot flushes.”

“The randomised trial found that it did reduce the number and severity of menopausal hot flushes in women taking hormone blocking treatments like tamoxifen. It found oxybutynin was just as effective as many other drugs available for those symptoms. It has its own side effects, but it is another option for women.”

Another quality of life study presented on the effects of exercise for patients during chemotherapy treatment found that patients who exercised during chemotherapy had better quality of life and their fatigue levels returned to the levels prior to their breast cancer diagnosis after treatment had concluded. Disappointingly, it was unable to show that exercise reduces the risk of breast cancer returning.

Immunotherapy

Immunotherapy continues to be a hot topic in oncology. Breast Cancer Trials recently opened two new immunotherapy trials in Australia called CHARIOT and DIAmOND.

At the 2018 ESMO conference in Munich, the results of another trial, IMpassion130, were presented. IMpassion130 was for women with triple negative metastatic breast cancer. They were given either nab-paclitaxel, a chemotherapy drug that is a current standard of care option, or nab-paclitaxel plus atezolizumab, an immunotherapy drug. This important study was the first phase three trial to show the benefits of immunotherapy in triple negative breast cancer. Further analysis of this clinical trial was presented at San Antonio.

“This analysis was specifically looking at a subset of women with triple negative breast cancers that were PDL1 positive, as they were the ones who benefited from the addition of atezolizumab. PDL1 is the biomarker for this drug. The immune cells have a signal on the surface called PDL1, so if the immune cells have that signal then the treatment works. If they don’t, the treatment doesn’t work,” Dr Zdenkowski said.

“This was an exploratory analysis and needs to be confirmed in other studies, but it is promising research.”

Issue 84
Summer 2019