AstraZeneca breast cancer drug camizestrant shows "sustained" benefit

(Alliance News) - AstraZeneca PLC on Tuesday reported encouraging test results for its breast cancer treatment camizestrant.

The Cambridge-based pharmaceutical firm said camizestrant when combined with a cyclin-dependent kinase inhibitor, such as palbociclib, ribociclib or abemaciclib, delayed time to first progression by 55%, and to second progression by 37%.

Testing was carried out among patients with advanced HR-positive breast cancer with an emergent ESR1 tumour mutation. Switching to AstraZeneca's treatment regime before progression in the first-line setting was compared to standard-of-care treatment with an aromatase inhibitor and CDK4/6 inhibitor.

AstraZeneca said its drug combination maintained a progression-free survival benefit at later follow-up stages, alongside showing an improvement in second progression-free survival. Analysis also indicated that the treatment reduced total circulating tumour DNA.

The company had reported previously that the regime had met its primary endpoint of progression-free survival, but noted the updated results as evidence that benefits were "sustained beyond initial progression".

Overall survival data, which will be confirmed in the final analysis stages, trended in favour of the camizestrant combination, AstraZeneca added.

Last week, the US Food & Drug Administration extended the review period for AstraZeneca's camizestrant filing to assess additional data. The FDA had granted "breakthrough therapy" status to the drug combination back in May 2025.

Camizestrant has already been approved in the United Arab Emirates and Saudi Arabia, while applications remain under review in Japan and other markets.

Susan Galbraith, the company's executive vice president of Oncology Haematology R&D commented on Tuesday: "More than half of patients who switched to the camizestrant combination completely cleared tumour DNA from their bloodstream compared to 2% with standard of care. This provides robust evidence that an early treatment switch has strong anti-tumour efficacy, and supports the potential for long-term clinical benefit. Switching to the camizestrant combination also extended the time patients lived without disease progression after first- and second-line treatment, delayed the need for more intensive therapies, and helped patients maintain their quality of life."

AstraZeneca shares fell 0.5% to 13,370.00 pence on Tuesday afternoon in London.

By Holly Munks, Alliance News reporter

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