Decision delivers the first ADC-based regimens for previously untreated triple-negative breast cancer across PD-L1 status, a PD-L1-positive Keytruda combination plus a monotherapy option for immunotherapy-ineligible patients.
The U.S. Food and Drug Administration on June 24, 2026, approved Trodelvy (sacituzumab govitecan-hziy), Gilead Sciences’ first-in-class Trop-2-directed antibody-drug conjugate (ADC), for the first-line treatment of adults with unresectable locally advanced or metastatic triple-negative breast cancer (TNBC). The decision clears two distinct uses: Trodelvy as a single agent for patients who are not candidates for PD-1 or PD-L1 inhibitor-based therapy, and Trodelvy in combination with Merck’s Keytruda (pembrolizumab), or its subcutaneous formulation, Keytruda Qlex, for patients whose tumors express PD-L1 (combined positive score, or CPS, of at least 10). It is the first ADC cleared in first-line metastatic TNBC, and the first to span the population regardless of PD-L1 status.
Two indications, split along the PD-L1 line
The dual label is strategically important because it carves first-line TNBC along the same PD-L1 boundary that already governs treatment. For patients whose tumors are PD-L1-negative or who are otherwise ineligible for checkpoint blockade, a large share of the first-line population, Trodelvy monotherapy now offers a non-immunotherapy alternative to single-agent chemotherapy. For PD-L1-positive disease, the Keytruda combination supplants the chemotherapy partner in the established immunotherapy backbone, with PD-L1 status determined by an FDA-authorized test. Reflecting the data, the NCCN has listed Trodelvy, with or without Keytruda, as a category 1 preferred first-line option for metastatic TNBC regardless of PD-L1 status.
The pivotal data
The approval rests on two Phase 3 trials. In ASCENT-03, which enrolled checkpoint-ineligible patients, Trodelvy monotherapy improved median progression-free survival (PFS) to 9.7 months versus 6.9 months for chemotherapy of physician’s choice, a 38% reduction in the risk of progression or death (hazard ratio 0.62; 95% CI, 0.50–0.77; p<0.0001). Confirmed objective response rate (ORR) was 50% versus 47%, and median duration of response was 12.2 versus 7.2 months.
In ASCENT-04/KEYNOTE-D19, 443 PD-L1-positive patients were randomized to sacituzumab govitecan plus pembrolizumab or chemotherapy plus pembrolizumab. The ADC combination extended median PFS to 11.2 months versus 7.8 months, a 35% risk reduction (hazard ratio 0.65; 95% CI, 0.51–0.84; p<0.001), with ORR of 60% versus 53% and a near-doubling of response duration (16.5 versus 9.2 months). Critically for investors weighing durability, overall survival (OS) data were immature at analysis; ASCENT-04 showed an early positive OS trend, but an OS benefit has not been established. Follow-up analyses indicated the PFS advantage persisted into the next line of therapy despite a crossover rate of roughly 80%.
What it means for Gilead, Merck, and the ADC field
For Gilead, the approval converts Trodelvy from a later-line product into a potential first-line backbone in TNBC’s most-treated setting, consequential because more than half of metastatic TNBC patients never receive treatment beyond first-line. Trodelvy is already a commercial anchor of Gilead’s oncology franchise, with more than 75,000 breast cancer patients treated across more than 60 countries, and the expansion materially enlarges its addressable population. It also helps Gilead hold ground against the rival Trop-2 ADC datopotamab deruxtecan from AstraZeneca and Daiichi Sankyo, keeping Trodelvy the first Trop-2 conjugate into frontline TNBC.
For Merck/MSD, the combination is the first randomized Phase 3 regimen to pair an ADC with a checkpoint inhibitor in first-line PD-L1-positive metastatic breast cancer, evolving the KEYNOTE-355 paradigm away from a chemotherapy partner. Folding in Keytruda Qlex, the subcutaneous version of the drug, threads the approval into Merck’s lifecycle strategy as the intravenous franchise approaches loss of exclusivity. More broadly, the decision is a milestone for the ADC field: it installs a Trop-2 conjugate as a frontline option and begins substituting targeted payload delivery for cytotoxic chemotherapy backbones in a solid tumor.
The bottom line
The significance is hard to overstate for a subtype that has seen few first-line advances in two decades. Gilead’s chief medical officer, Dietmar Berger, called the decision for the most aggressive breast cancer subtype
a new standard of care
Dietmar Berger/LinkedIn
Whether that designation holds will turn on maturing OS data, real-world tolerability of an ADC-anchored first line, and how clinicians sequence Trodelvy against later-line options now that it has moved up front. With datopotamab deruxtecan advancing and further ADC–immunotherapy combinations in trials, first-line TNBC is poised to become one of oncology’s more contested battlegrounds, and this approval makes Trodelvy the regimen to beat.
Key Data
- Approval: FDA, June 24, 2026, Trodelvy (sacituzumab govitecan-hziy) for first-line metastatic TNBC, as monotherapy and in combination with Keytruda or Keytruda Qlex (PD-L1 CPS ≥10).
- ASCENT-03 (monotherapy vs. chemotherapy): median PFS 9.7 vs. 6.9 months; HR 0.62 (0.50–0.77); p<0.0001; ORR 50% vs. 47%; DOR 12.2 vs. 7.2 months.
- ASCENT-04/KEYNOTE-D19 (plus pembrolizumab vs. chemotherapy plus pembrolizumab): median PFS 11.2 vs. 7.8 months; HR 0.65 (0.51–0.84); p<0.001; ORR 60% vs. 53%; DOR 16.5 vs. 9.2 months.
- Overall survival: immature in both trials; early positive OS trend in ASCENT-04, benefit not established.
- Guidelines: NCCN category 1 preferred first-line, across PD-L1 status.
Why It Matters
- First ADC in first-line metastatic TNBC across PD-L1 status, extending Gilead’s Trodelvy franchise from later lines into the largest-volume setting, where most patients never reach a second line.
- First ADC + PD-1 inhibitor combination approved in first-line PD-L1-positive breast cancer, reshaping Merck’s chemotherapy-anchored Keytruda backbone and dovetailing with the Keytruda Qlex lifecycle plan.
- Sharpens the Trop-2 ADC race against AstraZeneca/Daiichi Sankyo’s datopotamab deruxtecan, with Trodelvy claiming first-mover status in frontline TNBC.
- Validates the chemotherapy-to-ADC substitution thesis in solid tumors, though durability hinges on OS maturity and real-world tolerability.
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Written by: Semiramida Nina Markosyan, Editor, OncoDaily Canada