-- a pun on hairs. But splitting is because the new drugs, the ADC [antibody-drug conjugate] trastuzumab deruxtecan [Enhertu], is indicated for patients that have HER2 1+ or 2+ IHC, but not HER2 0.

HER2 is a tyrosine kinase receptor growth-promoting protein expressed on the surface of many types of tumors.11 HER2 expression (IHC 3+/ 2+) is present in 18% to 56% of endometrial cancers and is ...

– HER2-low (IHC 1+ or IHC 2+/ISH-) breast cancer, as determined by an FDA-approved test, who have received a prior chemotherapy in the metastatic setting or developed disease recurrence during ...

The highest response rates continued to be seen in the exploratory analysis of patients with tumor HER2 expression of immunohistochemistry (IHC) 3+ (n=75) as confirmed by central testing, where ...

HER2-positive status was detected in 3.1% (n=14 of 456) of samples in total, including 2.5% (n=4 of 163) of samples classified as IHC 0, and 3.4% (n=10 of 293) of samples classified as IHC 1+.

Locally advanced or metastatic HER2-positive (IHC 3+ or IHC 2+/ISH positive) gastric or gastroesophageal junction (GEJ) adenocarcinoma who have received a prior trastuzumab-based regimen ...

Locally advanced or metastatic HER2-positive (IHC 3+ or IHC 2+/ISH positive) gastric or gastroesophageal junction (GEJ) adenocarcinoma who have received a prior trastuzumab-based regimen ...

Trastuzumab deruxtecan was granted Breakthrough Therapy Designation in the U.S. for the treatment of adult patients with unresectable or metastatic HER2 low (IHC 1+ or IHC 2+/ISH-negative) breast ...

But based on some of these clinical trials, they were considered HER2-low, meaning there was HER2 expression assessed by IHC at low levels, 1+ or 2+, even though there was no gene amplification.

The Bottom Line The 2018 ASCO/CAP guidelines, which put an increased emphasis on interpreting HER2 status via immunohistochemistry and in-situ hybridization, have led to an increase in the ...