HQ Team
September 13, 2026: AstraZeneca’s end-stage trial of an experimental drug to treat breast cancer failed to prolong a patient’s life without the disease progressing or getting worse, according to the Anglo-Swedish company.
“The…Phase III trial of AstraZeneca’s Etcamah (camizestrant) in combination with palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, did not meet the primary endpoint of progression-free survival. However, a numerical improvement was observed in the upfront 1st-line treatment of patients with estrogen receptor (ER)-positive disease,” according to a company statement.
The company tested the medicine camizestrant in a large clinical study called SERENA-4. The medicine was tested in people with a type of advanced breast cancer called ER-positive, HER2-negative breast cancer. These patients had not yet received treatment for their advanced cancer, so this was being tested as their first treatment.
The researchers compared two treatments: Etcamah with palbociclib and anastrozole with palbociclib. Palbociclib is a medicine that helps slow down the growth of cancer cells.
‘Disappointed’
The main goal of the trial was to test whether Etcamah could help patients live longer without their cancer getting worse. This is called progression-free survival. The trial did not achieve its main goal. Although the people taking Etcamah had a numerically better result, the difference was not large or reliable enough to show that Etcamah was definitely better than anastrozole.
Etcamah performed slightly better, but the study could not prove it was better. The global trial enrolled 1,371 patients.
Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said: “Whilst we are disappointed by the SERENA-4 outcome, it sharpens our focus on maximising the number of patients who can benefit from Etcamah today based on SERENA-6 and reinforces the importance of ESRI testing for patients on first-line therapy.
“Early breast cancer represents an important opportunity, and we remain confident in the long-term potential of Etcamah in the early setting as we advance our broader programme.”
Leading cause
SERENA-6 study found that Etcamah can be useful for some patients whose cancer develops a change called an ESR1 mutation while they are receiving their first hormone-based treatment, and is the main reason why ESR1 testing may be important. A test can tell doctors whether a patient’s cancer has this particular change.
AstraZeneca is also testing Etcamah in people with early breast cancer. Two large studies, called CAMBRIA-1 and CAMBRIA-2, involve about 10,000 patients.
Breast cancer is the second most common cancer and one of the leading causes of cancer-related deaths worldwide. More than two million patients were diagnosed with breast cancer in 2024, with more than 690,000 deaths globally. While survival rates are high for those diagnosed with early breast cancer, only about 30% of patients diagnosed with or who progress to metastatic disease are expected to live five years following diagnosis.
HR-positive breast cancer, characterised by the expression of estrogen or progesterone receptors, or both, is the most common subtype of breast cancer, with 70% of tumours considered HR-positive and HER2-negative. ERs often drive the growth of HR-positive breast cancer cells. More than 97% of HR-positive breast cancer tumours are ER-positive.
