New Data And FDA Approval Brings Hope for Metastatic Triple-Negative Breast Cancer

Underscoring the importance of this approval and referencing the class of drugs to which Trodelvy belongs, Dr. Tiffany Traina, Breast Medical Oncologist at Memorial Sloan Kettering Cancer Center in New York, tells SurvivorNet, “this approval supports the growing body of evidence that antibody drug conjugates are a preferred treatment over chemotherapy.”

Understanding Trodelvy

Antibody drug conjugates deliver a dose of chemotherapy in a more targeted way and are sometimes likened to “smart bombs.” Triple negative breast cancer does not have estrogen receptors, progesterone receptors, or enough HER2 to be treated with many of the targeted medicines used for other breast cancers. That has historically left patients with fewer options.

Now, two phase 3 studies, ASCENT-03 and ASCENT-04/KEYNOTE-D19, are helping doctors understand whether a drug called Trodelvy should be used earlier in treatment for certain patients with advanced triple-negative breast cancer.

What Is An ADC?

Trodelvy is an antibody-drug conjugate, often called an ADC. In simple terms, it is designed to carry chemotherapy directly toward cancer cells by targeting Trop-2, a protein found on many tumor cells. The goal is to attack the cancer more directly while still recognizing that side effects can occur.

ASCENT-03 studied Trodelvy compared with chemotherapy in patients with previously untreated, locally advanced inoperable or metastatic triple-negative breast cancer who were not candidates for PD-1/PD-L1 immunotherapy. ASCENT-04/KEYNOTE-D19 studied Trodelvy plus pembrolizumab, an immunotherapy drug also known as Keytruda, compared with chemotherapy plus pembrolizumab in patients whose tumors expressed PD-L1.

Dr. Sara Tolaney, a breast medical oncologist at Dana-Farber Cancer Institute, told SurvivorNet that the newer data strengthen the case for using this type of treatment earlier.

“I think the data that we’re seeing really continued to confirm that Trodelvy should be a first-line standard of care option for our patients with metastatic triple-negative breast cancer,” Dr. Tolaney said.

Why Doctors Are Paying Attention

Both studies reported longer progression-free survival for the Trodelvy-containing treatment arms compared with chemotherapy-based treatment. Progression-free survival means the length of time before the cancer grows or spreads.

Dr. Tolaney also pointed to biomarker analyses from the studies. Biomarkers are features of the tumor, such as PD-L1 status, Trop-2 level, BRCA mutation status, or HER2 expression, that can sometimes help guide treatment.

“What we saw was that irrespective of biomarker that was looked at, benefit was always favoring the SG-containing arms compared to chemotherapy,” Dr. Tolaney said. “So I think that confirmed that you didn’t really need a biomarker to select patients.”

That does not mean every patient will receive the same treatment. Doctors still consider PD-L1 status, prior treatment, BRCA mutation status, other health issues, side effects, and patient preferences.

What Is Still Being Studied

One important caution: overall survival data from these studies are still immature. That means researchers need more follow-up time before they can say clearly whether patients are living longer overall.

The studies also allowed many patients in the chemotherapy group to cross over and receive Trodelvy after their cancer progressed. Dr. Tolaney said this was important because it allowed researchers to ask whether giving the ADC earlier still helped, even when many patients could receive it later.

“I think what we saw was in both ASCENT-03 and ASCENT-04, that PFS2 was longer in the Trodelvy-containing arms compared to chemo,” she said.

PFS2 looks beyond the first treatment and tracks how long patients go before progression on the next line of therapy. Dr. Tolaney noted that this endpoint has limitations, but said the high crossover rate made these studies especially informative.

A Reason for Hope With Realistic Expectations

For patients, the message is not that treatment is easy or one-size-fits-all. Trodelvy can cause side effects, including low white blood cell counts and diarrhea, and treatment decisions should be made carefully with an oncology team.

Still, Dr. Tolaney said the overall direction is encouraging.

“It used to be we only had chemotherapy available to our patients with metastatic triple-negative breast cancer,” she said. “And now things have really revolutionized where we have antibody drug conjugates.”

For patients facing metastatic triple-negative breast cancer, that progress matters. It means more conversations, more options, and more clinical trials asking how to improve treatment earlier.

Questions to Ask Your Doctor

• Could ASCENT-03 or ASCENT-04/KEYNOTE-D19 apply to my diagnosis?
• Is my cancer PD-L1 positive or PD-L1 negative?
• What are my treatment options right now?
• What are the possible benefits and risks of Trodelvy?
• Would pembrolizumab be part of my treatment plan?
• Are there clinical trials I should consider?
• How could this treatment affect my daily life?
• What side effects should I watch for, and when should I call the care team?

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