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A cancer with too much HER2 growth-signal protein, either scored 3+ on the stain or shown to have extra copies of the gene. Once the most aggressive breast cancer subtype, it is now among the most treatable thanks to anti-HER2 drugs.
About 15-20% of breast cancers and a similar share of gastric/GEJ cancers are HER2-positive by ASCO/CAP criteria (IHC 3+, or IHC 2+ with in situ hybridisation amplification). They receive trastuzumab, pertuzumab, T-DM1 and T-DXd in curative and metastatic settings, with response-adapted pathways (KATHERINE, DESTINY-Breast). HER2-low (IHC 1+ or 2+/ISH-negative) and ultralow tumours are not 'positive' but respond to T-DXd, so the category is now a spectrum. HER2 mutations (rather than amplification) in lung cancer are targeted by T-DXd and zongertinib; HER2 amplification also occurs in colorectal, bladder and biliary cancers.
In plain words · A growth-signal receptor. Some cancers make far too much of it, and drugs that block it or use it as a docking site have transformed those cancers.
Showing the target this term concerns: HER2.
The glossary entry explains the word; the readout page carries the scoring rule, the thresholds approvals use, the companion diagnostics and the tests.
A direct check of the HERIZON-BTC-01 testing algorithm in routine pathology: IHC 3+ can stand alone, 2+ needs ISH, and the low-level amplification in weakly stained tumours is the group where HER2 drugs are least likely to help.
The prevalence estimate that made HER2 the first gallbladder-relevant target; it argues for testing every advanced gallbladder cancer, since one in five may qualify for zanidatamab or trastuzumab deruxtecan.
ToGA made gastric cancer the second disease treated by HER2 status and introduced gastric-specific HER2 scoring. It is the base on which trastuzumab deruxtecan and pembrolizumab combinations in HER2-positive gastric cancer have built.
Shares HER2 IHC 2+ (equivocal, reflex to ISH), HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2 IHC 3+ (HER2-positive by immunohistochemistry), HER2-low and HER2-ultralow.
Shares Reflex HER2 testing of every advanced gallbladder and extrahepatic biliary cancer, HER2 IHC 2+ (equivocal, reflex to ISH), HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 ISH amplified (ERBB2 gene amplification).
Shares HER2 IHC 2+ (equivocal, reflex to ISH), HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2 IHC 3+ (HER2-positive by immunohistochemistry), HER2-low and HER2-ultralow.
Shares HER2 testing in the UK: reflex ISH, the ratio against the copy number, and where the UK differs from ASCO/CAP, Receptor conversion: when the receptors change between the primary and a recurrence, Grade, stage and receptor status: three different things on one breast report, Hormone receptor status (ER / PR).
Shares HER2 ISH amplified (ERBB2 gene amplification), Gene amplification and copy-number change, HER2 IHC 3+ (HER2-positive by immunohistochemistry), FISH / ISH (in situ hybridisation).
Shares HER2 testing in biliary tract cancer (IHC, ISH and NGS), HER2 IHC 3+ (HER2-positive by immunohistochemistry), FISH / ISH (in situ hybridisation), Immunohistochemistry (IHC).
Shares HER2 IHC and ISH companion assays (HercepTest, PATHWAY 4B5, HER2 Dual ISH), HER2 IHC 3+ (HER2-positive by immunohistochemistry), HER2-low and HER2-ultralow, Immunohistochemistry (IHC).
Shares APHINITY, HER2 IHC 3+ (HER2-positive by immunohistochemistry), Pertuzumab, Trastuzumab.