ASCENT-03 Trial Supports Standard Use of Sacituzumab Govitecan in mTNBC

Among patients treated with sacituzumab govitecan, median PFS by blinded independent central review was 9.7 months compared with 6.9 months with chemotherapy.

Sacituzumab govitecan (Trodelvy) reduced the risk for disease progression or death by 38% vs chemotherapy in patients with previously untreated, locally advanced, unresectable or metastatic triple-negative breast cancer (mTNBC) who are ineligible for PD-1 or PD-L1 inhibitors, according to a presentation of the phase 3 ASCENT-03 trial (NCT05382299) at the 2025 European Society for Medical Oncology Congress.1,2

In addition to its statistically significant and clinically meaningful improvement in progression-free survival (PFS), the agent induced a superior duration of response (DOR) with no new safety signals.

“These data might support a potential new standard, potential good option for patients with triple-negative breast cancer when they develop metastasis and are unable to receive immune checkpoint inhibitors,” Javier C. Cortés, MD, PhD, head of the International Breast Cancer Centre in Barcelona, Spain, said during a presentation of the data.

How Did Sacituzumab Govitecan Perform Against Chemotherapy in mTNBC?

Among patients treated with sacituzumab govitecan, median PFS by blinded independent central review (BICR) was 9.7 months (95% CI, 8.1-11.1) compared with 6.9 months (95% CI, 5.6-8.2) with chemotherapy (HR, 0.62; 95% CI, 0.50-0.77; P < .001). Further, PFS rates were superior with sacituzumab govitecan compared with chemotherapy at 6 months (65% [95% CI, 59%-71%] vs 53% [95% CI, 47%-59%], respectively) and 12 months (41% [95% CI, 34%-47%] vs 24% [95% CI, 19%-30%]).

When assessed by the investigators, PFS in the sacituzumab govitecan arm was 9.6 months (95% CI, 8.3-10.6) compared with 6.8 months with chemotherapy (95% CI, 5.6-7.2; HR, 0.64; 95% CI, 0.52-0.79). The 6- and 12-month PFS rates with sacituzumab govitecan were 65% (95% CI, 59%-70%) and 52% (95% CI, 46%-58%), respectively, compared with 38% (95% CI, 32%-44%) and 22% (95% CI, 17%-27%) with chemotherapy.

PFS benefit was observed across all patient subgroups, including by age, ECOG performance status (PS), geographic region, disease state, PD-L1 status, and chemotherapy selection prior to random assignment.

In addition, the objective response rate (ORR) with sacituzumab govitecan was 48% (95% CI, 42%-54%) compared with 46% (95% CI, 40%-52%) for those who received chemotherapy (stratified OR, 1.1; 95% CI, 0.8-1.6). In the sacituzumab govitecan and chemotherapy arms, respectively, 20 patients (7%) and 15 patients (5%) experienced a complete response, 115 (41%) and 112 (40%) had a partial response, 113 (41%) and 101 (36%) had stable disease, and 14 (5%) and 36 (13%) developed progressive disease.

“Objective response rates were similar in both treatment groups; however, duration of response was substantially longer with sacituzumab govitecan vs chemotherapy,” Cortés noted. Median DOR was 12.2 months (95% CI, 9.7-13.8) with sacituzumab govitecan compared with 7.2 months for chemotherapy (95% CI, 5.7-8.4).

Time to response (TTR) by BICR was 1.6 months in both the sacituzumab govitecan (95% CI, 0.7-16.7) and chemotherapy (95% CI, 0.9-6.8) groups.

Overall survival (OS) data were not mature at the time of the presentation; however, Cortés acknowledged that, of the 179 patients who initiated subsequent treatment after chemotherapy, 147 (82%) received sacituzumab govitecan.

At the time of the presentation, median OS was 21.5 months (95% CI, 17.7-not reached [NR]) and 20.2 months (95% CI, 18.2-NR), respectively (HR, 0.98; 95% CI, 0.75-1.30).

Median PFS2 was 18.2 months (95% CI, 15.9-NR) and 14.0 months (12.5-17.4) with sacituzumab govitecan and chemotherapy, respectively (HR, 0.70; 95% CI, 0.55-0.90).

What Are the Adverse Events Associated With Sacituzumab Govitecan?

The median duration of treatment with sacituzumab govitecan was 8.3 months (range, < 0.1-28.7).

Treatment-emergent adverse events (TEAEs) occurred in 99% and 97% of patients in the sacituzumab govitecan and chemotherapy arms, respectively, with grade 3 or higher events occurring in 66% and 62%, with 61% and 53% being treatment related.

In total, 71 serious TEAEs occurred in the sacituzumab govitecan arm, of which 46 were treatment related. TEAEs led to treatment discontinuation in 10 patients, whereas 181 and 101 patients experienced dose interruptions and reductions, respectively. There were 7 TEAEs leading to death with sacituzumab govitecan. Cortés noted that the majority were due to infections, including 5 infections that were secondary to neutropenia. None of the 5 patients, who each had risk factors for febrile neutropenia, received prophylaxis with granulocyte colony-stimulating factor.

The most common grade 3 or higher AEs included neutropenia (43%), diarrhea (9%), and leukopenia (7%). The incidence of AEs that led to discontinuation of sacituzumab govitecan or chemotherapy was 4% and 12%, respectively.

What Are the Unmet Needs in Advanced TNBC?

“Chemotherapy, for many years, has been the mainstay of treatment for metastatic triple-negative breast cancer compared with other subtypes, and the absolute improvements in median overall survival have been relatively modest over time,” Ana C. Garrido-Castro, MD, medical oncologist at Dana-Farber Cancer Institute and assistant professor of medicine at Harvard Medical School in Boston, Massachusetts, said during an invited discussion of the presentation.

“And the sobering truth is that across studies in the US and Europe, approximately 25% to 30% of patients diagnosed with metastatic TNBC are no longer alive at 6 months from their metastatic diagnosis, and 6 months is just about the median PFS of first-line chemotherapy. So if there is a new drug that is able to significantly improve PFS with an acceptable toxicity profile, this should be sufficient to change the current standard of care in the first-line setting.”

According to Cortés, most patients with previously untreated mTNBC are not candidates to receive treatment with a PD-(L)1 inhibitor. Further, approximately half of the patients treated in the first line do not go on to receive a second line of therapy. “Unfortunately, the great majority of our patients will experience progressive disease, and we need to treat them with subsequent lines of therapies,” he added. “There is an urgent need for improved therapeutic options in earlier lines of therapy to delay progression and time to next line of treatment.”

How Was the ASCENT-03 Trial Conducted?

Sacituzumab govitecan is approved to treat metastatic TNBC in the second-line setting and beyond as well as for the treatment of patients with pretreated hormone receptor–positive/HER2-negative metastatic breast cancer globally.

The investigators conducted the international, phase 3, open-label, randomized trial of sacituzumab govitecan in patients with previously untreated, locally advanced, unresectable or metastatic TNBC who are not candidates for immune checkpoint therapy.

In the trial, investigators randomly assigned patients 1:1 to receive either 10 mg/kg intravenous sacituzumab govitecan on days 1 and 8 of 21-day cycles (n = 279) or one of the following chemotherapy regimens (n = 279): 90 mg/m2 paclitaxel or 100 mg/m2 nab-paclitaxel on days 1, 8, and 15 of 28-day cycles or 1000 mg/m2 gemcitabine plus carboplatin area under the curve 2 on days 1 and 8 of 21-day cycles.

Treatment was continued until BICR-verified progression or unacceptable toxicity. Eligible patients were offered to cross over to receive second-line sacituzumab govitecan following BICR-verified disease progression.

Patients were eligible for the trial if they were not candidates for PD-(L)1 inhibitors and were in the curative setting for 6 months or less since treatment. Previously treated, stable central nervous system metastases were allowed.

“Knowing that sacituzumab govitecan crossover could impact their final OS results and complicate, potentially, their path toward regulatory approval, the study team should be applauded,” Garrido-Castro commented. “In my opinion, inclusion of crossover should be considered for therapies with known overall survival advantage, particularly in those patient populations with poor prognosis, though we and regulatory agencies must be thoughtful then of how to interpret the results and the impact of crossover.”

PFS, assessed by BICR, served as the primary end point of the study. Secondary end points included OS, ORR, DOR, TTR by BICR, safety, and quality of life.

In the sacituzumab govitecan and chemotherapy arms, median age was 56 (range, 22-84) and 54 years (range, 23-86), respectively. The majority were White (64% each), had an ECOG PS of 0 (66% vs 67%), had PD-L1–negative disease (99% each), had lung metastases (59% vs 61%), and received prior neoadjuvant therapies (66% vs 68%). Further, 48% of patients in each arm experienced recurrence after 12 months or more following curative treatment.

References

1. Cortés JC, Bardia A, Punie K, et al. Primary results from ASCENT-03: a randomized phase III study of sacituzumab govitecan (SG) vs chemotherapy (chemo) in patients (pts) with previously untreated advanced triple-negative breast cancer (TNBC) who are unable to receive PD-(L)1 inhibitors (PD-[L]1i). Abstract presented at: European Society for Medical Oncology Congress 2025; October 17-21, 2025; Berlin, Germany. Abstract LBA20.
2. Cortés J, Punie K, Barrios C, et al. Sacituzumab govitecan in untreated, advanced triple-negative breast cancer. N Engl J Med. Published online October 18, 2025. doi:10.1056/NEJMoa2511734