Triple-Negative Breast Cancer – FDA First-Line Approval for Datopotamab Deruxtecan

On 22 May 2026, the US Food and Drug Administration (FDA) approved, for adult patients with unresectable or metastatic triple-negative breast cancer (TNBC) who are not eligible for PD-1/PD-L1 inhibitor therapy, datopotamab deruxtecan-dlnk . Daiichi Sankyo developed the medicine under the brand name Datroway . Because this approval is based on TROPION-Breast02, which enrolled patients who had not received chemotherapy or another systemic anticancer treatment for unresectable or metastatic disease, in this specific clinical context it should be regarded as a first-line metastatic treatment approval .

This approval is in the first-line metastatic disease setting; however, it does not cover all patients with TNBC, but those who are not eligible for PD-1/PD-L1 inhibitor therapy . This ineligibility may result from PD-L1 negativity, previous immunotherapy in the early-stage setting, contraindications such as autoimmune disease or immunosuppression, or barriers to accessing/administering immunotherapy.

Datopotamab deruxtecan's FDA journey: From HR+/HER2- breast cancer to EGFR-mutant lung cancer

Datopotamab deruxtecan was first approved by the FDA in 2025. Thus, this new triple-negative breast cancer approval is not the medicine's first FDA approval; rather, it represents an important first-line expansion for patients with metastatic TNBC who are not candidates for immunotherapy .

This table also shows the medicine's development trajectory: first, previously treated HR+/HER2- metastatic breast cancer; then EGFR-mutant lung cancer previously treated with EGFR-targeted therapy and platinum chemotherapy; and now a move into earlier treatment of triple-negative breast cancer, namely first-line metastatic therapy.

This TNBC approval is in the first-line treatment setting for metastatic disease

This point should be made especially clear: Patients enrolled in TROPION-Breast02 had not previously received chemotherapy or another systemic anticancer therapy for unresectable or metastatic breast cancer. Therefore, the current FDA approval is considered in the setting of first-line systemic therapy for the metastatic / unresectable stage of the disease.

The nuance to note is that a patient may previously have received neoadjuvant or adjuvant treatment in the early-stage setting. However, the critical criterion of the study was no prior systemic treatment for metastatic or unresectable disease. Thus, this is not an approval for previously treated second-line TNBC in metastatic disease.

A Trop-2-targeted medicine, but no TROP2 testing requirement for the TNBC approval

Datopotamab deruxtecan is a Trop-2-directed antibody–drug conjugate. This naturally raises the question: Must tumor Trop-2 expression be assessed to use this medicine?

In the current FDA approval and prescribing information for the triple-negative breast cancer indication, a mandatory TROP2 expression test or an FDA-approved companion diagnostic is not specified as a requirement. Patient selection is primarily based on these clinical criteria: a diagnosis of triple-negative breast cancer, unresectable or metastatic disease, and not being a candidate for PD-1/PD-L1 inhibitors.

A new option in metastatic triple-negative breast cancer for patients who are not candidates for immunotherapy

Because triple-negative breast cancer lacks the estrogen receptor, progesterone receptor and HER2 target, it cannot benefit from conventional endocrine therapies or HER2-targeted agents. Treatment in the metastatic stage therefore relied largely on chemotherapy for a long time. In recent years, immunotherapy and antibody–drug conjugates have begun to change this field; however, not every patient is eligible for PD-1 or PD-L1 inhibitor therapy.

The FDA approval of datopotamab deruxtecan concerns precisely this patient group: Adult patients with unresectable or metastatic triple-negative breast cancer who cannot receive PD-1/PD-L1 inhibitors. Thus, the approval is not a general alternative to immunotherapy for all patients with TNBC; it is a new first-line treatment option that fills a specific clinical gap.

A phase 3 study with 644 patients: ADC versus standard chemotherapy

The approval was based on TROPION-Breast02 , a multicenter, open-label, randomized phase 3 study. The study enrolled 644 patients with unresectable or metastatic triple-negative breast cancer. These patients had not previously received chemotherapy or another systemic anticancer therapy for metastatic disease and were not candidates for PD-1/PD-L1 inhibitors.

The study included both de novo metastatic patients and patients with recurrent disease. Patients with PD-L1-negative tumors could enroll; those who were PD-L1-positive but could not receive immunotherapy because of prior neoadjuvant/adjuvant PD-1/PD-L1 inhibitor use, a comorbidity preventing immunotherapy, or lack of access to PD-1/PD-L1 inhibitors in their country were also included. Patients with a known germline pathogenic BRCA variant could enroll if they were not eligible for a PARP inhibitor.

Patients were allocated to two arms in a 1:1 ratio: 323 patients received datopotamab deruxtecan, 321 patients received physician's choice chemotherapy . Chemotherapy options were paclitaxel, nab-paclitaxel, capecitabine, eribulin or carboplatin. Randomization was balanced by geographic region, PD-L1 status and history of disease-free interval.

PFS almost doubled: 10,8 months versus 5,6 months

One of the strongest findings was the progression-free survival result. Median progression-free survival in the datopotamab deruxtecan arm was 10,8 months compared with 5,6 months in the chemotherapy arm. The hazard ratio was 0,57 ; this value corresponds to approximately a 43% relative reduction in the risk of disease progression or death.

An absolute gain of 5 months in overall survival

Overall survival data also favored datopotamab deruxtecan. Median overall survival was 23,7 monthsin the datopotamab deruxtecan arm and 18,7 months in the chemotherapy arm. The difference was 5 months . The hazard ratio was 0,79 and corresponds to approximately a 21% relative reduction in the risk of death.

A significant difference in overall survival is particularly important in a difficult-to-treat disease such as metastatic triple-negative breast cancer. Some new medicines may produce tumor shrinkage or a PFS advantage, but their contribution to overall survival may not always be clear. In this study, PFS, OS and response rate all improved in the same direction.

Objective response rate more than doubled: 64% versus 30%

Confirmed objective response rate in the datopotamab deruxtecan arm was %64, compared with %30 in the chemotherapy arm. This means that patients receiving datopotamab deruxtecan had more than twice the probability of marked tumor shrinkage compared with chemotherapy.

A Trop-2-targeted antibody–drug conjugate: Chemotherapy directed at the cancer cell

ILD, ocular toxicity and stomatitis require close monitoring

The FDA prescribing information highlights four main safety warnings for datopotamab deruxtecan: interstitial lung disease / pneumonitis, ocular adverse reactions, stomatitis / oral mucositis and embryo-fetal toxicity.

In the TROPION-Breast02 safety data, the rate of serious adverse reactions among patients with TNBC receiving datopotamab deruxtecan was %17 . In one patient, corresponding to %0,3 , a fatal adverse reaction due to ILD/pneumonitis was reported. Permanent treatment discontinuation occurred in %4,7, dose interruption in %35, and dose reduction in %28 of patients.

Recommended dose: 6 mg/kg every 21 days

The recommended datopotamab deruxtecan dose is 6 mg/kg. For patients weighing 90 kg or more , the maximum dose is 540 mg . The medicine is administered by intravenous infusion every 3 weeks, that is, in cycles of 21 days. Treatment continues until disease progression or unacceptable toxicity.

The ADC era is moving into earlier treatment lines in triple-negative breast cancer

The approval of datopotamab deruxtecan shows that antibody–drug conjugates are beginning to play a strong role in triple-negative breast cancer not only in later lines but also in earlier metastatic treatment lines. Improved disease control duration and overall survival compared with standard chemotherapy, especially in patients not candidates for PD-1/PD-L1 inhibitors, place this medicine at a noteworthy point in the clinical algorithm.

The FDA review was conducted through international cooperation

This review was carried out under the FDA Oncology Center of Excellence's Project Orbis initiative. Project Orbis provides a framework for simultaneous or coordinated review of oncology medicines by international regulatory agencies.

In this process, the FDA collaborated with Australia's TGA, Brazil's ANVISA, Health Canada, Singapore's HSA and Switzerland's Swissmedic. Although FDA approval has been granted, applications may still be under review at the other regulatory agencies.

A triple gain over chemotherapy: Longer PFS, longer OS and higher response

The FDA approval of datopotamab deruxtecan is an important development that strengthens the rise of ADC therapies in triple-negative breast cancer. TROPION-Breast02 showed that, in patients with unresectable or metastatic TNBC who were not candidates for PD-1/PD-L1 inhibitors, datopotamab deruxtecan, compared with standard chemotherapy, extended progression-free survival by approximately 5,2 months, overall survival by 5 months and increased the objective response rate from 30% to 64% .

These results provide a new treatment option in clinical practice. However, the best setting for its use should be determined by jointly assessing PD-L1 status, previous immunotherapy, BRCA status/PARP inhibitor eligibility, disease burden, ocular risks, lung toxicity risk and the patient's overall condition.