New Enhertu use, new HER2 complexities
September 2024—Every profession has its own news cycle. In pathology, the story arc is often a lengthy one, stretching from clinical triumph to Now what? Such is the case with expanded use of trastuzumab deruxtecan, which was granted accelerated FDA approval in late April for adult patients with unresectable or metastatic HER2-positive (IHC 3+) solid tumors who received prior systemic treatment and have no alternative treatment options. Three multicenter trials evaluated the efficacy of the drug: DESTINY-PanTumor02, DESTINY-Lung01, and DESTINY-CRC02. PanTumor02 looked at seven tumor cohorts: endometrial, cervical, ovarian, bladder, biliary tract, pancreatic, and other solid cancers (excluding breast, colorectal, gastric, and non-small cell lung cancers). The results of these trials often were striking (median duration of response for PanTumor02 was 19.4 months, for example), and physicians are now looking closely at this tumor-agnostic (also referred to as tissue-agnostic) indication.