AstraZeneca and Daiichi Sankyo's TROP2-directed antibody-drug conjugate (ADC) Datroway (datopotamab deruxtecan) has been approved in the EU for the first-line treatment of adults with unresectable or metastatic triple-negative breast cancer (TNBC) who are not candidates for PD-1/PD-L1 inhibitor therapy, setting up a showdown with Gilead Sciences Trodelvy (sacituzumab govitecan).Last month, Trodelvy — also a TROP2-directed ADC — gained EU approval as monotherapy for first-line patients with unresectable or metastatic TNBC who cannot receive PD-(L)1 inhibitors. The clearance was based on progression-free survival data from the Phase III ASCENT-03 study, in which Trodelvy reduced the risk of disease progression or death by 38% compared to standard chemotherapy.Meanwhile, Datroway's latest approval was based on findings from the Phase III TROPION-Breast02 trial, which included patients with metastatic TNBC who experienced early relapse following prior treatment. Results presented at last year's European Society for Medical Oncology (ESMO) congress showed that Datroway demonstrated a statistically significant and clinically meaningful 5-month improvement in median overall survival (OS) versus investigator's choice of chemotherapy, whilst reducing the risk of disease progression or death by 43%."With this approval, Datroway is the only TROP2-directed antibody drug conjugate approved in the EU that has demonstrated an overall survival benefit in the first-line setting," said Ken Keller, global head of oncology business at Daiichi. The therapy gained a similar US label expansion in May.Despite its first-mover advantage in TNBC in the US, doctors recently polled by FirstWord expect there to be room for multiple entrants in the space. For more, see — Physician Views Results: Though Datroway is first to front line, oncologists see room for two (or more) in TROP2 ADC showdown.Shortly after the poll was fielded, Trodelvy won a US label expansion for front-line use as monotherapy to treat adults with unresectable, locally advanced or metastatic TNBC who cannot receive PD-(L)1 therapy. The nod was accompanied by a second approval to include use in combination with Merck & Co.'s Keytruda (pembrolizumab), or the Keytruda Qlex-branded subcutaneous formulation of the PD-1 inhibitor, as a first-line treatment for adults with unresectable, locally advanced or metastatic TNBC whose tumours express PD-L1.