ESMO Congress 2026

The value of antibody-drug conjugates (ADCs) over chemotherapy in advanced HR+/HER2- breast cancer has phase 3 underpinnings: in TROPION-Breast01, among patients progressing on endocrine therapy after one to two prior lines of chemotherapy, the TROP2 ADC datopotamab deruxtecan versus investigator's choice chemotherapy (ICC) yielded a PFS hazard ratio by BICR of 0.63 (95% CI 0.52-0.76), with nausea (any grade 51.1%, grade >=3 1.4%) and stomatitis (any grade 50%, grade >=3 6.4%) the most common TRAEs ^[1]; more broadly, ADC development around targets such as HER2 has become a driving force reshaping breast cancer treatment ^[4]. The question APEX-Breast01 addresses is whether the same logic holds in a HER2-low population with no prior chemotherapy in the advanced setting.

LBA27 presented at this ESMO is the phase 3 APEX-Breast01: the biparatopic HER2 ADC TQB2102 (also referred to in on-site posts as Rolditamig DXd), developed by CTTQ, versus TPC chemotherapy. The study enrolled 543 patients with HER2-low recurrent/metastatic breast cancer and no prior chemotherapy in the advanced setting, randomized to TQB2102 7.5 mg/kg Q3W or TPC (capecitabine/paclitaxel/nab-paclitaxel); data cutoff was May 31, 2026. Median PFS was 16.4 vs 5.5 months (HR 0.29, p<0.0001), consistent in both HR+/HER2-low and all HER2-low; ORR was 68.8% vs 31.0%; OS showed a clear benefit trend (HR 0.44) but data are immature. Safety was manageable: grade >=3 neutropenia was most common, TRAE discontinuation was 1.5% in each arm, and ILD occurred in 2.2%, mostly grade 1-2. An NDA has been submitted in China.

Relative to existing knowledge, the readout advances on three fronts. In magnitude, the ADC-versus-chemotherapy PFS HR was 0.63 in TROPION-Breast01 ^[1] versus 0.29 here — though the control arms differ (ICC of eribulin/vinorelbine/capecitabine/gemcitabine ^[1] vs capecitabine/paclitaxel/nab-paclitaxel here), so this is only a cross-trial indirect comparison. In population, this study enrolled patients with no prior advanced chemotherapy, whereas TROPION-Breast01 required one to two prior lines ^[1], a clear shift toward earlier lines. In technical route, a biparatopic HER2 ADC achieved deep responses in HER2-low disease (ORR 68.8% vs 31.0%); on-site commentators summarized the magnitude as 'new ADC, same ~0.3 hazard ratio' and called for head-to-head trials.

The limitations should be stated plainly: OS data remain immature and long-term safety awaits follow-up; cross-trial HR comparisons are only directional; the available information comes from a phase 3 conducted in China with a China NDA submitted, and its generalizability and the drug's exact position within the ADC sequence await head-to-head trials and longer-term data.