# Advancements in HER2-positive cancer treatments

> Live situation record from CLSTR: https://clstr.news/situations/advancements-in-her2-positive-cancer-treatments
> Updated: 2026-09-03T13:00:16.000Z. Sources: 7. Developments: 3.

Regulatory bodies have issued new approvals for treatments targeting HER2-positive cancers. In late August 2026, the European Medicines Agency (EMA) issued a positive opinion for using trastuzumab deruxtecan in combination with pertuzumab as a first-line treatment for adult patients with unresectable or metastatic HER2-positive breast cancer. This recommendation follows the Phase III DESTINY-Breast09 study, which showed a median progression-free survival of 40.7 months compared to 26.9 months with the previous standard regimen.

On September 3, 2026, the European Commission officially approved the combination of trastuzumab deruxtecan and pertuzumab. Based on the DESTINY-Breast09 trial, the combination demonstrated a 44% reduction in the risk of disease progression or death compared to the standard treatment of taxane, trastuzumab, and pertuzumab (THP). The trial also reported an objective response rate of 85.1%, which exceeded the 78.6% observed with the standard treatment. This antibody-drug conjugate is marketed through an alliance between Daiichi Sankyo and AstraZeneca.

In the United States, the FDA has approved zanidatamab-hrii (Ziihera) for the first-line treatment of patients with unresectable, locally advanced, or metastatic HER2-positive adenocarcinoma of the stomach, gastroesophageal junction, or esophagus. This approval is supported by the Phase III HERIZON-GEA-01 study, which demonstrated a 28% reduction in the risk of death and a median overall survival of 26.4 months, compared to 19.2 months with the previous standard of trastuzumab and chemotherapy.

Medical experts noted that while standard therapies have existed for over a decade, these advancements address ongoing challenges regarding resistance to anti-HER2 therapies in highly morbid neoplasms.

## Timeline

### 2026-09-03: European Commission approves new HER2-positive breast cancer treatment

The European Commission approved trastuzumab deruxtecan and pertuzumab as a first-line treatment for metastatic HER2-positive breast cancer, significantly reducing disease progression risk.

2 sources. https://clstr.news/cluster/european-commission-approves-new-her2-positive-breast-cancer-treatment

### 2026-08-28: FDA approves zanidatamab for HER2-positive gastric cancer treatment

The FDA has approved zanidatamab for first-line treatment of HER2-positive gastric and esophageal adenocarcinomas, showing improved survival rates when combined with chemotherapy and immunotherapy.

4 sources. https://clstr.news/cluster/fda-approves-zanidatamab-hrii-for-her2-positive-adenocarcinoma

### 2026-08-24: EMA recommends new first-line treatment for HER2-positive breast cancer

The EMA has recommended trastuzumab deruxtecan and pertuzumab as a new first-line treatment for HER2-positive metastatic breast cancer, significantly improving progression-free survival rates.

2 sources. https://clstr.news/cluster/ema-recommends-new-first-line-treatment-for-her2-positive-breast-cancer

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Cite as: Advancements in HER2-positive cancer treatments. CLSTR, https://clstr.news/situations/advancements-in-her2-positive-cancer-treatments