Biopharmaceutical company AstraZeneca plc (STO:AZN) (LON:AZN) (NYSE:AZN) disclosed on Monday that its Phase III SERENA-4 trial of Etcamah (camizestrant) in combination with palbociclib did not achieve its primary endpoint of a statistically significant improvement in progression-free survival, although a numerical improvement was observed.

The trial evaluated the combination against anastrozole plus palbociclib in patients with estrogen receptor-positive, HER2-negative advanced breast cancer who had not received systemic treatment for advanced disease.

AstraZeneca said Etcamah remains the only oral SERD to demonstrate benefit in the first-line setting and it is approved in the United States, European Union, Japan and several other countries for patients with an emergent or detected ESR1 mutation during first-line endocrine-based therapy, based on SERENA-6.

The safety profile of Etcamah with palbociclib was consistent with the known profiles of both medicines, with no new safety concerns identified.

Susan Galbraith, AstraZeneca's executive vice president of Oncology Haematology R&D, said the SERENA-4 result sharpens the company's focus on maximising Etcamah's current opportunity based on SERENA-6 and reinforces the importance of ESR1 testing during first-line therapy.

Etcamah is also being studied in approximately 10,000 patients in the CAMBRIA-1 and CAMBRIA-2 Phase III trials. The trials are evaluating Etcamah in the adjuvant setting among patients at intermediate and high risk of recurrence, including as monotherapy, in combination with CDK4/6 inhibitors and following CDK4/6 inhibitor treatment.