News > New breast cancer drugs and treatment combinations show promise across subtypes | ASCO 2025

New breast cancer drugs and treatment combinations show promise across subtypes | ASCO 2025

Four studies offer potential new ways to treat certain breast cancers with better outcomes

BY: Jamie Kudera
06/04/25

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At this year’s American Society for Clinical Oncology annual meeting, researchers shared promising new treatment options for early-stage as well as advanced or metastatic breast cancer. Below we share four highlights — a new drug, new combination therapies, and dosing changes — that are poised to offer better outcomes than current standard therapies for people with breast cancer.

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New PROTAC drug outperforms fulvestrant, on track for FDA approval

New targeted therapy: Vepdegestrant

Type of medication: Proteolysis-targeting chimera (PROTAC) estrogen receptor degrader (a new type of drug)

How it’s used: To treat advanced ER+/HER2-negative breast cancer with ESR1 mutation previously treated with a CDK 4/6 inhibitor

How it’s different: Vepdegestrant is a new medicine taken daily as a pill. It works by targeting and binding two molecules, ultimately breaking down estrogen receptors.

What the study found: Vepedegestrant delayed cancer growth or spread longer than fulvestrant in people with advanced ER+, HER2- breast cancer with the ESR1 mutation (an average of 5 months vs. 2.1 months). At six months, twice as many people receiving vepedegestrant did not have cancer growth or spread compared to fulvestrant (45.2% vs. 22.7%). The benefit was only seen in people with ESR1 mutations.

Side effects: Vepdegestrant was well-tolerated. Only 3% of people stopped taking the drug due to side effects, and only 2% needed a lower dose. The most common side effects were fatigue, elevated liver levels, and nausea. Vomiting and diarrhea were rare.

Study details: VERITAC-2, a phase 3, randomized trial, enrolled 624 people with advanced ER+, HER2-negative breast cancer from 213 health care sites in 25 countries. All participants had prior treatment with hormonal therapy and a CDK 4/6 inhibitor. They had not had chemotherapy.

Key takeaway: This study will likely lead to FDA approval of a new drug option for previously treated, advanced, ER+, HER2-negative breast cancer with ESR1 mutation. We do not yet know how doctors will decide when to use this drug versus other options such as elacestrant.

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New combination of existing drugs poised to become new first-line treatment for PD-L1+ advanced triple-negative breast cancer

Combination Therapy: Sacituzumab govitecan (Trodelvy) and pembrolizumab (Keytruda)

Type of medication: Combination of antibody-drug conjugate (ADC) TROP-2 directed targeted therapy and checkpoint inhibitor immunotherapy

How it’s used: First treatment for advanced triple-negative breast cancer that tests positive for PD-L1

How it’s different: This study is the first to test an ADC/checkpoint inhibitor combination therapy for untreated, PD-L1+, advanced triple-negative breast cancer (TNBC).

What the study found: The combination of sacituzumab plus pembrolizumab resulted in longer time without cancer growth than chemotherapy plus pembrolizumab (11.2 months vs. 7.8 months). When tumors shrank or disappeared, the effect lasted 7.3 months longer with the new combination. The early data also suggest a possible benefit for overall survival.

Side effects: Side effects were common, with one-third of participants reporting at least one moderate or severe side effect. Giving the two drugs together did not result in any new or worse side effects than either alone. Over half of people receiving SG/pembro experienced neutropenia, nausea, fatigue, hair loss, or diarrhea, with 43% having moderate to severe neutropenia and 10% reporting moderate to severe diarrhea.

Study details: The international ASCENT-04/KEYNOTE-D19 phase 3 randomized clinical trial enrolled 442 people with PD-L1+ advanced TNBC who had never been treated for TNBC or were at least six months past treatment for early-stage disease. They were randomized to receive either sacituzumab govitecan plus pembrolizumab or chemotherapy plus pembrolizumab. They were followed for an average of 15 months at the time of this report.

Key takeaway: The combination of SG plus pembrolizumab may soon become the standard first treatment for PD-L1+ advanced TNBC.

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Gradual dose increases when starting abemaciclib (Verzenio) reduces side effects in early-stage breast cancer

Therapy: Abemaciclib (Verzenio)

Type of medication: CDK 4/6 Inhibitor

How it’s used: To treat advanced and high-risk, early-stage HR+, HER2- breast cancer (taken with estrogen therapy)

How it’s different: Abemaciclib is an effective treatment for high-risk, early-stage hormone-receptor positive, HER2-negative breast cancer yet people often stop taking the drug early on due to side effects such as diarrhea. This study tests a gradual dosing strategy.

What the study found: This study found that starting the drug gradually over the first month reduced side effects and enabled 70.8% of people to reach the target drug dose, compared to 60% in monarchE, the clinical trial that led to FDA approval.

Side effects: The most common side effects are neutropenia, diarrhea, and fatigue. Diarrhea peaked at 19.1% at eight weeks then declined. Overall, fewer people experienced milder side effects with the new dosing approach.

Study details: The phase 2 TRADE study tested a drug escalation approach in 89 people with high-risk, stage 2 or stage 3, HR+, HER2- breast cancer. Participants took a 50 mg pill for two weeks followed by a 100 mg pill for two weeks before moving to the recommended dose of 150 mg. This study looked at results at 0-4 weeks, 4-8 weeks, and 8-12 weeks.

Key takeaway: Increasing the dose gradually over the first month enabled more people to stay on the target dose of abemacicilib. Some people continued on the drug at a lower dose. Current prescribing practices may make it hard to use this approach widely. The research team hopes the drug maker will consider changing the packaging to make this easier.

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Combining two HER2 therapies as first treatment improves outcomes

Therapy: Trastuzumab deruxtecan (Enhertu) plus pertuzumab (Perjeta)

Type of medication: Combination anti-HER2 therapy

How it’s used: To treat advanced or metastatic HER2-positive breast cancer

How it’s different: This treatment combines two anti-HER2 drugs as a first therapy for a more powerful effect.

What the study found: Trastzumab deruxtecan plus pertuzumab (T-DXd+P) reduced risk of disease progression or death by 44%, compared to the standard therapy, THP (taxane plus trastzumab plus pertuzumab). People taking T-DXd+P went 40.7 months without cancer getting worse compared to 26.9 months with THP. Early data suggest that the dual therapy may improve overall survival too.

Side effects: Combining T-DXd and pertuzumab did not raise any new safety concerns. The most common side effects experienced by people receiving T-DXd+P were nausea and diarrhea, followed by neutropenia, fatigue, hair loss, and vomiting. The dual therapy was more likely than THP to cause moderate to serious side effects resulting in more dose interruptions and reductions. There were six treatment-related deaths on the trial, five in the T-DXd+P group and one in the THP group.

Study details: The global DESTINY-BREAST09 phase 3 randomized trial included 1,157 people with advanced/metastatic HER2-positive breast cancer. The trial included people with both hormone receptor-positive and hormone receptor-negative breast cancers, as well as asymptomatic brain metastases. T-DXd+P was more effective across subgroups.

Key takeaway: Trastzumab deruxtecan plus pertuzumab may become the new standard first therapy for advanced HER2+ breast cancer. Questions remain about dosing, length of time on therapy, and whether everyone needs to receive the very strong drug combination up front.

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New breast cancer drugs and treatment combinations show promise across subtypes | ASCO 2025

On this page

New PROTAC drug outperforms fulvestrant, on track for FDA approval

New combination of existing drugs poised to become new first-line treatment for PD-L1+ advanced triple-negative breast cancer

Gradual dose increases when starting abemaciclib (Verzenio) reduces side effects in early-stage breast cancer

Combining two HER2 therapies as first treatment improves outcomes

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New breast cancer drugs and treatment combinations show promise across subtypes | ASCO 2025

On this page

New PROTAC drug outperforms fulvestrant, on track for FDA approval

New combination of existing drugs poised to become new first-line treatment for PD-L1+ advanced triple-negative breast cancer

Gradual dose increases when starting abemaciclib (Verzenio) reduces side effects in early-stage breast cancer

Combining two HER2 therapies as first treatment improves outcomes

Newsflash:

Related resources

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