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Neoadjuvant T-DXd followed by THP outpaced the standard chemo regimen in shrinking HER2-positive early breast cancer tumors on MRI, but imaging responses didn't reliably predict whether patients achieved a pathologic complete response (pCR). Data from the phase 3 DESTINY-Breast11 trial, presented at the 2026 ESMO Congress, show the combo's mid-treatment response rate was 77.3% vs. 50.8% for the comparator — yet MRI alone isn't enough to guide treatment decisions.
Neoadjuvant fam-trastuzumab deruxtecan (T-DXd) followed by paclitaxel, trastuzumab, and pertuzumab (THP) produced faster and deeper tumor shrinkage on MRI compared to the standard dose-dense doxorubicin/cyclophosphamide (ddAC) followed by THP regimen in patients with HER2-positive early breast cancer. Results from an exploratory analysis of the phase 3 DESTINY-Breast11 trial were presented at the 2026 ESMO Congress.
Despite the impressive imaging responses, MRI proved to be a poor predictor of pathologic complete response (pCR) — the gold-standard surgical outcome. Notably, more than half of patients who didn't show a complete or partial response on mid-treatment MRI with T-DXd/THP still went on to achieve pCR, underscoring that imaging alone shouldn't drive treatment decisions. The FDA approved T-DXd followed by a taxane-based regimen for early-stage HER2-positive breast cancer in May 2026, based on the trial's primary analysis.
By the Numbers
Why it matters: T-DXd/THP is cementing its role as a powerful neoadjuvant option for HER2+ early breast cancer, but this analysis sends an important clinical signal — MRI responses, while encouraging, shouldn't be used to cut treatment short or redirect therapy. Completing the full regimen remains key.
