Triple-negative breast cancer (TNBC) is one of the most aggressive and hard-to-treat forms of breast cancer. It tends to grow quickly and has limited treatment options, especially once the disease is advanced or has spread to other parts of the body. Recently published results from a major phase 3 clinical trial show that combining two cancer drugs — sacituzumab govitecan (Trodelvy®) and pembrolizumab (Keytruda®) — significantly improved outcomes for patients with PD-L1-positive advanced TNBC. These findings, now published in the New England Journal of Medicine, could change how doctors treat this difficult cancer subtype.
What Is Triple-Negative Breast Cancer and Why It’s Hard to Treat
Triple-negative breast cancer gets its name because the cancer cells lack three common receptors (estrogen, progesterone, and HER2) that many other breast cancers have. Because of this, TNBC does not respond to hormonal therapies or HER2-targeted drugs that work well in other breast cancer types.
TNBC represents about 15 % of breast cancer cases and often affects younger women. When it becomes locally advanced or metastatic (spread to other parts of the body), the disease is especially tough to control. Median survival for metastatic TNBC is low compared with other breast cancer types, and new treatments are urgently needed.
How do these Drugs Work
Sacituzumab govitecan is an antibody-drug conjugate (ADC) that delivers chemotherapy directly to cancer cells by targeting a protein called Trop-2, which is common on TNBC cells. Pembrolizumab is an immune checkpoint inhibitor that helps the immune system recognize and attack cancer cells.
The study was a randomized, open-label, phase 3 clinical trial that enrolled 443 patients with previously untreated, PD-L1-positive unresectable or metastatic TNBC. Patients were randomly assigned (like flipping a coin) to receive one of two treatment strategies:
- Sacituzumab govitecan plus pembrolizumab
- Chemotherapy plus pembrolizumab
Patients received the medications in cycles (every 21 days) and were followed to compare how long they lived without their cancer getting worse.
What the Trial Found: Better Control of Cancer Growth
The primary goal of the study was progression-free survival (PFS) — how long patients lived without evidence of cancer progression or death. The results clearly favored the new combination:
- Patients treated with sacituzumab govitecan plus pembrolizumab had a median PFS of 11.2 months.
- Patients who received chemotherapy plus pembrolizumab had a median PFS of 7.8 months.
- This represents a 35 % reduction in the risk of disease progression or death with the combination treatment.
These results reached high statistical significance, meaning the improvement was unlikely due to chance. In addition, early signals suggested a trend toward improved overall survival, although final survival data are still immature and longer follow-up is needed.
Why These Results Are Important
This trial is one of the first to show that combining an antibody-drug conjugate with an immune checkpoint inhibitor can improve outcomes in the first-line treatment of PD-L1-positive metastatic TNBC. Until now, standard first-line care typically combined chemotherapy with pembrolizumab alone, and many patients still experienced rapid disease progression.
The combination of sacituzumab govitecan and pembrolizumab improved not just how long patients lived without progression, but also response rates and duration of response, meaning more patients had meaningful shrinkage of their tumors for longer periods.
Experts say these findings support using this combination as a potential new standard of care for patients with PD-L1-positive TNBC — a group that previously had limited first-line treatment options.
What This Means for Patients and Clinicians
For people living with PD-L1-positive, advanced TNBC, this research represents a significant step forward. Patients may soon have access to a treatment option that keeps their cancer from progressing for longer than standard therapy alone did.
It’s also a sign that targeted ADC therapy and immunotherapy can work together effectively in aggressive cancers, potentially opening the door to similar approaches in other tumor types.
However, as with all cancer treatments, decisions about therapy should be made with a healthcare team, considering individual health, cancer characteristics, and treatment goals.
Source:
Tolaney SM, et al. Sacituzumab govitecan plus pembrolizumab vs chemotherapy plus pembrolizumab for previously untreated PD-L1-positive advanced triple-negative breast cancer: phase 3 ASCENT-04/KEYNOTE-D19 trial. N Engl J Med. 2026;doi:10.1056/NEJMoa2508959. Accessed by: https://pubmed.ncbi.nlm.nih.gov/41564397/
