HER-2 T862A

P2, N=102, Active, not recruiting, AstraZeneca | Trial completion date: Jan 2028 --> Jul 2026

Our data demonstrated the clinical benefit of anti-HER2 treatment in Chinese breast cancer patients harboring HER2 mutation and/or HER2 fusion. The value of immunotherapy and treatment selection among individual HER2 variants needs further study.

P1, N=30, Recruiting, National Cancer Institute (NCI) | N=18 --> 30

HER2 mutations drive the growth of a subset of breast cancers and are targeted with HER2 tyrosine kinase inhibitors (TKI) such as neratinib...Cells expressing double HER2 mutations exhibited resistance to most HER2 TKIs but retained sensitivity to mobocertinib and poziotinib...Double-mutant cells showed enhanced MEK/ERK signaling, which was blocked by combined inhibition of HER2 and MEK. Together, these findings reveal the driver function of secondary HER2 mutations in resistance to HER2 inhibition and provide a potential treatment strategy to overcome acquired resistance to HER2 TKIs in HER2-mutant breast cancer.

In heavily pretreated pts with limited Tx options, T-DXd demonstrated encouraging anticancer activity and long DoR across multiple tumor types with HER2m and a range of HER2 expression levels, with a known safety profile. Translational research will help characterize pts who may derive greatest benefit from T-DXd.

Among patients with any ERBB2 mutations, 7 received a combination of chemotherapy plus anti-EGFR, either cetuximab or panitumumab, 6 had PR and 1 SD as best response. In this consecutive real-world series, ERBB2 activating mutation prevalence was 3.1%. We found an addition 4.4% ERBB2 VUS prevalence, with a ERBB2 mutation prevalence of 7.5% as a whole. Pathogenetic mutations can co-occur with other driver molecular alterations.

HER2 mutations are most common in EC among gynecologic cancers, with R678Q most frequent in our cohort, and T862A in cBioportal. While no HER2 -mutated tumors had a 3+ IHC score, increased HER2 expression (2+) was seen in tumors with L313V, R678Q, and T862A mutations, and HER2 rearrangement. Targeted therapy has already been applied in other tumor types with these HER2 mutations; however, further studies are necessary to explore the prognostic and therapeutic implications of these findings in gynecologic cancers.

P1, N=18, Recruiting, National Cancer Institute (NCI) | Not yet recruiting --> Recruiting

P1, N=18, Not yet recruiting, National Cancer Institute (NCI) | Trial completion date: Aug 2023 --> Jun 2024 | Trial primary completion date: Aug 2023 --> Jun 2024

P1, N=18, Not yet recruiting, National Cancer Institute (NCI)