ASCO 2025: BREAST CANCER RESEARCH SUMMARY

Highlights from the 2025 ASCO Annual Meeting

The American Society of Clinical Oncology (ASCO) Annual Meeting is one of the most important events in the global cancer calendar, where researchers and clinicians gather to share the latest advances in cancer care. This year’s conference, held in Chicago, featured exciting developments in breast cancer research — many of which are expected to change treatment options and improve outcomes for women diagnosed with the disease.

Here are some of the key highlights from ASCO 2025, summarised for our community.

A Promising New First-Line Treatment for HER2-Positive Breast Cancer

A major focus of this year’s meeting was the DESTINY-Breast09 trial, which compared two treatment combinations for women with HER2-positive metastatic breast cancer. The new combination of trastuzumab deruxtecan (T-DXd) and pertuzumab significantly extended the time patients lived without their cancer getting worse — to over 40 months on average, compared to the current standard treatment.

This breakthrough offers new hope for many women, especially as not all patients are able to move on to second-line treatments. While some side effects were reported (including lung inflammation in a small number of patients), this new approach is likely to set a new standard in care.

Reducing Treatment Side Effects Without Sacrificing Effectiveness

The NeoCARHP trial looked at whether a less intensive chemotherapy combination could still be effective for women with HER2-positive early breast cancer. The results showed that dropping one of the drugs (carboplatin) didn’t reduce the treatment’s success, and side effects like low blood counts, nausea, and kidney issues were lower with less chemotherapy.

This could mean a gentler option for some women — particularly those with stage I–II disease — while still achieving excellent outcomes.

Hormonal Therapy Side Effects: A New Non-Hormonal Option for Hot Flushes

Many women who take hormonal therapy for breast cancer experience distressing side effects like hot flushes and insomnia. A new drug called elinzanetant, taken as a daily pill, showed promising results in reducing both the frequency and severity of these symptoms.

What’s exciting is that it works in a non-hormonal way and most women in the trial chose to keep taking it long-term.

Understanding When to Use Targeted Drugs: The FINER and VERITAC-2 Trials

Two trials provided new insights into targeted therapies for women with ER-positive, HER2-negative metastatic breast cancer who had already received standard treatments:

• FINER looked at adding a drug called ipatasertib to hormonal therapy. It helped slow the disease down even in women without the expected genetic changes — showing it may work for a broader group than previously thought. The FINER trial was conducted by Breast Cancer Trials in partnership with the Canadian Cancer Trials Group. Find out more about the FINER clinical trial results.
• VERITAC-2 explored a new class of targeted therapy (called PROTACs) with a drug named vepdegestrant. Women whose cancers had developed a particular mutation (ESR1) saw the most benefit. This highlights the growing importance of genetic testing to guide treatment.

Associate Professor Andrew Redfern is the Study Chair of the FINER clinical trial.

Detecting Cancer Progression Sooner Using Blood Tests

The SERENA-6 trial focused on using blood tests (ctDNA) to detect signs of cancer returning before symptoms or scans show anything. Women who had a particular mutation (ESR1) found in their blood were switched early to a different hormonal therapy (camizestrant) — and this helped delay the cancer’s return.

This “early warning” approach could become an important tool in the future, although more research is needed to understand its impact on overall survival and quality of life.

Good News for Younger Women: Long-Term Results from the SOFT/TEXT Trial

Fifteen-year follow-up results from the SOFT and TEXT trials — run in Australia by Breast Cancer Trials — continue to show strong benefits for premenopausal women with early ER-positive breast cancer. Women under 40, or with more aggressive tumours, gained the most from combining ovarian suppression with exemestane.

These long-term data reassures us that treatment decisions made early can continue to make a difference many years later.

Find out more about the practice changing SOFT and TEXT clinical trials here.

New Hope for Women with Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is one of the hardest types to treat. The ASCENT-04 trial showed that a new combination of sacituzumab govitecan (a targeted therapy) with immunotherapy (pembrolizumab) helped women with advanced TNBC live longer before their cancer worsened.

This could offer a more effective first-line treatment for women with PD-L1 positive TNBC, giving them the best possible chance upfront.

Ribociclib Benefits Hold Strong Across Ages and Menopausal Status

The NATALEE clinical trial is exploring a treatment called ribociclib used alongside an aromatase inhibitor for people with early-stage, hormone receptor-positive breast cancer that carries an intermediate to high risk of returning.

The results so far have been promising: the combination significantly reduces the chance of cancer coming back. Importantly, this benefit continues even after completing the full three-year course of ribociclib. This is reassuring news for people with both stage II and stage III breast cancer.

One of the big questions was whether age or menopausal status affected how well the treatment worked. This latest analysis showed that ribociclib works consistently well across all age groups and regardless of whether someone is pre- or postmenopausal. Younger people were slightly more likely to stick with the treatment—possibly because they were more motivated to do everything they could to reduce their risk—but everyone appeared to benefit similarly.

Using a standard quality-of-life questionnaire, researchers found that patients across all age groups and menopause statuses reported similar experiences—suggesting that the treatment is tolerable and manageable for most people.

Targeted therapy for difficult to treat metastatic breast cancer

The INAVO 120 trial added a targeted drug, invaolisib, to standard treatment of palbociclib and fulvestrant, in first line therapy for metastatic ER+/HER2 negative breast cancer with a PIK3CA mutation. Inavolisib, a highly specific inhibitor of PI3K, prolonged patients’ survival from 27 months with standard treatment, to 34 months with the three drug combination. This drug also led to a 2 year longer time interval until chemotherapy was needed for patients.

These results support the use of this medication in the clinic as an effective, specific approach for the 40% of patients whose cancers harbour the targetable mutation.

Can Patients Be Safely Re-Treated After Side Effects?

Finally, a study looking at women who had experienced lung side effects from T-DXd found that many were able to restart the drug safely after recovery, and continue benefiting from it. This may help doctors make more confident decisions about restarting treatment when appropriate.

What This Means for You

Many of the updates shared at ASCO 2025 could lead to new treatment options and better outcomes — especially in tailoring therapies to a woman’s type of breast cancer and individual circumstances. Medications in Australia need to be approved by regulatory bodies and then funded by the PBS before becoming routinely available.

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