5 Key Takeaways From ASCO 2026

This year’s American Society of Clinical Oncology (ASCO) delved into exciting clinical trials for various types of breast cancer, GLP-1 use, and more.

Breast Cancer Research Foundation (BCRF) investigators were among the over 20,000 attendees at the 2026 American Society of Clinical Oncology (ASCO) annual meeting, the largest international conference dedicated to oncology research. Among the exciting topics discussed were breast cancer advancements across a range of areas. Here are the ASCO 2026 key takeaways, including updates in metastasis, treatment, immunotherapy, GLP-1 use, breast cancer risk, and more.

More patients may safely forgo chemotherapy, study suggests

That’s the key takeaway from the phase 3 OPTIMA trial, which suggests that some patients with clinically high-risk, estrogen receptor (ER)-positive, HER2-negative early breast cancer may be able to safely avoid chemotherapy if their tumor biology indicates a low risk of the cancer coming back. Until now, genomic tests (tests analyzing DNA) have primarily helped identify lower-risk patients who may not need chemotherapy.

Building on BCRF-supported studies such as TAILORx, RxPONDER, and MINDACT, OPTIMA expanded the use of genomic testing to a higher-risk group, including patients with up to nine positive lymph nodes or tumors at least 30 mm in size—patients who have traditionally been treated with chemotherapy because of their clinical risk. Instead of Oncotype DX or MammaPrint (existing genomic tests), investigators used the 50-gene Prosigna test to generate a Risk of Recurrence (ROR) score and guide treatment decisions. Notably, Prosigna was developed based on BCRF supported studies on the PAM-50 gene assay.

In the test-directed group, patients with low risk of recurrence scores received endocrine therapy alone, while those with high risk of recurrence scores received chemotherapy followed by endocrine therapy. The study found that about 68% of these clinically high-risk patients were classified as low genomic risk and could forgo chemotherapy. Five-year invasive breast cancer-free survival was 90.3% in the Prosigna-guided group versus 91.8% in the standard chemotherapy group, showing very similar outcomes despite less chemotherapy use.

The findings also provided important evidence for premenopausal women age 40 and older receiving ovarian function suppression, a group in which genomic testing has historically been less established.

Overall, OPTIMA is considered a potentially practice-changing study because it further advances personalized treatment, helping identify which patients are likely to benefit from chemotherapy and which may be spared its short- and long-term side effects.

GLP-1s Impact on breast cancer risk and recurrence

Another ASCO 2026 key takeaway, intriguing new data from studies examining glucagon-like peptide-1 (GLP-1) receptor agonists—including medications such as semaglutide and tirzepatide, originally developed to treat diabetes and obesity—highlighted growing evidence that metabolic health may influence cancer risk and outcomes. For years, researchers have known that obesity is associated with an increased risk of developing and dying from breast and other cancers. Two studies in patients with breast cancer taking GLP-1 medications reported its impact on incidence and recurrence:

• In one study of more than 110,000 women with obesity, GLP-1 use was associated with approximately a 30% lower incidence of breast cancer. However, this observational study does not prove that GLP-1s directly prevents breast cancer.
• A second study looked at patients already diagnosed with cancer. Investigators found that patients taking GLP-1 medications were less likely to progress to metastatic disease in several obesity-related cancers, including breast, colorectal, lung, and liver. Patients receiving GLP-1 medications had a 43% lower risk of progression to stage IV disease compared with patients receiving other classes of diabetes medications.

Both studies are observational—meaning that cause has yet to be proven. It’s important to note that GLP-1 use was linked to higher risks of endometrial cancer and osteoporosis. Whether any benefit is driven by weight loss, reduced inflammation or insulin levels, or direct biological effects of the drugs is still unclear. More research is needed before GLP-1s can be considered a cancer prevention or treatment strategy—and more research is warranted.

Promising news for metastatic triple-negative breast cancer

Triple-negative breast cancer (TNBC) is historically difficult to treat as it lacks three key targets of treatment (ER, PR, and HER2). Researchers at ASCO 2026 highlighted some trials that may signal good news for those with metastatic TNBC (mTNBC).

• Phase 3 PANKU-BREAST02 Trial: Iza-bren, a first-in-class bispecific antibody-drug conjugate (ADC) targeting two cancer-specific proteins, showed promising early results in metastatic TNBC treated with one to two prior chemotherapies. Iza-bren is an experimental ADC, a type of targeted therapy that delivers cancer-fighting medicine directly to tumor cells. The drug is “bispecific,” designed to target two proteins found on some breast cancer cells simultaneously: EGFR and HER3. Iza-bren is the first bispecific ADC being tested in breast cancer. Safety was manageable, with notable blood count decreases and low rates of interstitial lung disease—a key concern for ADCs. More data is needed, but these findings are an exciting step for this hard-to-treat population.
• ASCENT03 Trial: Researchers tested Sacituzumab govitecan (SG) versus chemotherapy in patients not eligible for immunotherapy with a PD-L1 inhibitor. SG is an ADC that targets the TROP2 protein found on some breast cancer cells, delivering an attached toxic drug straight to tumors; PD-L1 inhibitor is a type of immunotherapy drug that blocks the PD-L1 protein, which cancer cells use to “hide” from the immune system. Results showed that SG achieved progression-free survival of six to nine months longer compared to chemotherapy.
• ASCENT04 Trial: Researchers tested SG plus pembrolizumab versus chemotherapy plus pembrolizumab (anti-PD-L1 immunotherapy) in the first line metastatic setting. Patients with mTNBC were previously untreated and PD-L1-positive. This study also showed SG outperformed chemotherapy, both with pembrolizumab: the progression-free survival was 14 months longer in the SG arm.
• TROPION Breast02: This trial demonstrated improvements in secondary endpoints with the ADC Datopotomab deruxtecan (Dato-DXd) compared with investigator choice chemotherapy. Results were consistent with the dual primary endpoints of overall survival and progression-free survival: Progression-free survival was 5 to 10 months longer compared to chemotherapy and overall survival showed a 21% reduction in risk of death. These data support the drug as a new first line standard of care for patients with an inoperable return of cancer cells in or near the original site of cancer, or metastatic TNBC for those in which immunotherapy is not an option.
• KEYNOTE522 Trial: The trial’s seven-year follow-up confirmed that adding monoclonal antibody drug, pembrolizumab, to chemotherapy (neoadjuvant and adjuvant) significantly improves outcomes in high-risk early-stage TNBC—85.1% vs 77.2% overall survival—helping patients stay cancer-free for longer and reduced the risk of the cancer spreading to other parts of the body, supporting its potential use as a standard treatment. The trial was discussed during the Bernie Fisher symposium session, supported by BCRF, is named for one of the giants in breast cancer research, Dr. Bernie Fisher.
• P-RAD Trial: Also a part of the Bernie Fisher symposium session, BCRF-investigator, Dr. Alice Ho, presented the primary results of P-RAD, a trial designed to test if preoperative radiation can act as a primer to enhance immunotherapy with pembrolizumab. The study group tested two doses of radiation (9Gy and 24Gy) and used T-cell infiltration (TCI) as a primary goal—TCI indicates if the immune system has been activated. They found an increase in TCI with both doses: 80% at 9Gy and 82% at 24Gy. Studies are ongoing but this is encouraging evidence that radiation can prime the immune system to make immunotherapy more effective in TNBC.

Developments for HR-positive/HER2-negative breast cancer

Researchers also presented findings in HR-positive/HER2-negative breast cancer treatments:

• SERENA-6 Trial: Insights from phase 3 of the trial in HR-positive, HER2-negative breast cancer found that switching to camizestrant (a novel oral SERD) plus a CDK4/6 inhibitor upon detection of an emergent ESR1 mutation outperformed continuing aromatase inhibitor-based therapy, delivering a 7.6-month median progression-free survival gain, with roughly a third of patients still progression-free at 24 months. The data on circulating tumor (ctDNA) DNA were striking with analyses at four and eight weeks showing total ctDNA clearance in 51% of camizestrant patients versus just 1.9% on standard-of-care. Overall survival data are not complete at 23.5 months, but with no new safety signals and meeting the study’s primary goals, the case for switching to camizestrant in this setting is compelling. Based on these results, the FDA granted camizestrant breakthrough therapy designation, but full approval is still pending.
• LidERA Trial: Phase 3 of this trial evaluated Giredestrant, a next-generation oral SERD, in people with ER-positive/HER2-negative early breast cancer after surgery. The FDA granted priority review for the medication. In the study, researchers found a 30% reduction in the risk of invasive recurrence or death compared with standard endocrine therapy. The study team found that the benefit was seen regardless of menopausal status, suggesting the treatment may benefit a range of patients with ER-positive/HER2-negative early breast cancer: The risk of metastatic disease was reduced by 42% in premenopausal women and 24% in postmenopausal women. In terms of side effects, joint and muscle pain are the most common reasons patients stop endocrine therapy early. In the trial, stopping treatment due to musculoskeletal pain was less than half as common with Giredestrant when compared with standard endocrine therapy across menopausal groups. Since ER-positive/HER2-negative breast cancer accounts for about 70% of all breast cancer diagnoses, a treatment that improves outcomes and is easier to stay on for longer could have a meaningful impact.

AI is moving fast in oncology

At ASCO 2026, two presentations showed what the use of AI looks like in breast cancer. BCRF investigator Dr. Corey Speers demonstrated that AI could extract predictive signals directly from pathology slides and clinical data, potentially identifying which patients need chemotherapy without additional testing. Dr. Luke Pike of Memorial Sloan Kettering demonstrated that AI could flag patients at highest risk for brain metastases before they become clinically apparent—allowing for earlier intervention rather than reactive management. Both approaches mine existing clinical data to make care more precise and proactive, no new infrastructure required. These presentations illustrated how the power of AI can be leveraged in innovative ways to improve breast cancer care, moving it from a research tool to clinical reality. Its scalability and ability to transcend borders positions AI to substantially impact real-world breast cancer care and delivery.

Pancreatic cancer drug appears promising

The biggest ASCO 2026 key takeaway was in one of the deadliest cancers, pancreatic cancer. A new drug that targets a protein, KRAS, that drives over 90% of pancreatic cancers, and for decades has been called “undruggable,” doubled survival without cancer progression compared to standard of care in previously treated patients.  This new drug is a pill that has far fewer side effects than standard chemotherapy. While the way the drug works (and the trial data) is specific to pancreatic cancer, any potential role in breast cancer would depend on future research into RAS protein‑driven breast cancers and targeted trials. For now, breast cancer treatment decisions are based on established molecular testing and approved therapies.

What these mean for the future of breast cancer

ASCO 2026 highlighted promising advances that could help reshape breast cancer care in the years ahead. Presentations showcased how foundational science underpins what happens in the clinic: discovery bench science gets translated to the clinic, then clinical research into patient-centric care, and innovative approaches into different real-world environments. From new targeted therapies to strategies that may improve outcomes and quality of life, these advancements emphasize the power of research to drive progress.

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