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AstraZeneca (AZN) gets CHMP backing for camizestrant in ESR1-mutated breast cancer

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Rhea-AI Filing Summary

AstraZeneca reports that the EU’s CHMP has issued a positive opinion recommending approval of camizestrant, an investigational next‑generation oral SERD, in combination with a CDK4/6 inhibitor as 1st‑line treatment for ER‑positive, HER2‑negative locally advanced or metastatic breast cancer with an emergent ESR1 mutation.

The recommendation is based on the Phase III SERENA‑6 trial, where the camizestrant combination cut the risk of disease progression or death by 56% versus an aromatase inhibitor plus CDK4/6 inhibitor, improving median progression‑free survival to 16.0 months from 9.2 months. A later analysis showed a statistically significant improvement in time to second progression and maturing overall‑survival data trending in favour of camizestrant. Safety was consistent with known profiles of the component drugs.

Camizestrant is already approved in the UAE and Saudi Arabia in this setting, and regulatory applications are under review in the US, Japan and other countries, underscoring AstraZeneca’s broader strategy in HR‑positive breast cancer and its expanding oncology portfolio.

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Insights

CHMP backs camizestrant after strong PFS data, advancing AstraZeneca’s HR-positive breast cancer franchise.

The CHMP’s positive opinion for camizestrant plus CDK4/6 inhibitors in 1st-line ER-positive, HER2-negative advanced breast cancer reflects compelling Phase III SERENA-6 data. The regimen reduced progression or death risk by 56% versus aromatase inhibitor plus CDK4/6 inhibitor, extending median progression-free survival from 9.2 to 16.0 months.

A later analysis showed longer time to second progression at 25.7 versus 19.1 months and overall survival still maturing in favour of camizestrant (hazard ratio 0.87). Safety aligned with known profiles, with low discontinuation rates. If the European Commission follows the CHMP opinion, camizestrant could become a key 1st-line option for ESR1-mutated disease and strengthen AstraZeneca’s competitive position in HR-positive breast cancer.

Risk reduction in progression or death 56% Camizestrant + CDK4/6 vs aromatase inhibitor + CDK4/6 in SERENA-6
Median progression-free survival (camizestrant combo) 16.0 months SERENA-6 primary endpoint
Median progression-free survival (control) 9.2 months Aromatase inhibitor + CDK4/6 arm in SERENA-6
Hazard ratio for PFS 0.44 Camizestrant combo vs control; 95% CI 0.31-0.60; p<0.00001
PFS2 camizestrant combo 25.7 months Time to second disease progression in later analysis
PFS2 control 19.1 months Comparator arm in later SERENA-6 analysis
Hazard ratio for PFS2 0.63 Camizestrant combo vs control; 95% CI 0.46-0.86; p=0.00373
SERENA-6 enrollment 315 patients HR-positive, HER2-negative advanced breast cancer with emergent ESR1 mutation
SERD medical
"Camizestrant is an investigational, potent, next-generation oral selective estrogen receptor degrader (SERD) and complete antagonist"
A SERD is a type of drug that binds to and helps remove or disable estrogen receptors on cancer cells, preventing estrogen from telling those cells to grow. For investors, SERDs matter because they represent potential treatments for hormone-driven cancers; clinical trial results, regulatory approvals, and competition can strongly affect a drug developer’s sales prospects, valuation, and partnership or acquisition opportunities, much like a new technology changing a market leader’s outlook.
CDK4/6 inhibitor medical
"camizestrant in combination with a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) has been recommended"
A CDK4/6 inhibitor is a type of cancer drug that blocks two proteins (CDK4 and CDK6) that tell cells to divide, effectively slowing or stopping the growth of tumors. Think of it as cutting power to a photocopier that keeps making cancer cells; that control can shrink tumors or delay progression. For investors, these drugs matter because clinical trial results, regulatory approvals, patent life, safety issues and competition directly affect sales potential and company value.
ESR1 mutation medical
"breast cancer upon detection of ESR1 mutation and without disease progression during 1st-line endocrine therapy"
An ESR1 mutation is a change in the gene that makes the estrogen receptor, a protein that acts like a lock on certain cells; when altered, that lock can behave differently. For investors, these mutations matter because they can make hormone drugs less effective or change which treatments and tests are needed, much like a changed lock driving demand for new keys and locksmith services — affecting drug sales, clinical trial success, and the market for diagnostics and follow‑on therapies.
progression-free survival medical
"median progression-free survival (PFS) 16.0 versus 9.2 months"
Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.
circulating tumour DNA medical
"first global, double-blind, registrational Phase III trial to use a circulating tumour DNA (ctDNA)-guided approach"
Phase III trial medical
"The Committee for Medicinal Products for Human Use based its positive opinion on the results from the pivotal SERENA-6 Phase III trial"
A phase III trial is a large, late-stage clinical study that tests whether a new drug or medical treatment works and is safe in a broad group of patients; think of it as the final road test before regulators decide if a product can be sold widely. Investors watch these trials closely because positive results often trigger regulatory approval and major increases in a company’s value, while failures can sharply reduce prospects and share price.

FORM 6-K
 
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
 
 
Report of Foreign Issuer
 
Pursuant to Rule 13a-16 or 15d-16 of
the Securities Exchange Act of 1934
 
For the month of May 2026
 
Commission File Number: 001-11960
 
AstraZeneca PLC
 
1 Francis Crick Avenue
Cambridge Biomedical Campus
Cambridge CB2 0AA
United Kingdom
 
 
Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.
 
Form 20-F X Form 40-F __
 
Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):
 
Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ______
 
Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.
 
Yes __ No X
 
If “Yes” is marked, indicate below the file number assigned to the Registrant in connection with Rule 12g3-2(b): 82-_____________
 
 
 
 
 
 
 
AstraZeneca PLC
 
INDEX TO EXHIBITS
 
 
1.
Camizestrant recommended for breast cancer in EU
 
 
 26 May 2026
 
Camizestrant in combination with a CDK4/6 inhibitor recommended for approval in the EU by CHMP for 1st-line advanced ER-positive breast cancer
 
Recommendation based on SERENA-6 Phase III trial results which showed combination reduced the risk of disease progression or death by 56% in patients with an emergent ESR1 tumour mutation
 
If approved, camizestrant has the potential to reshape 1st-line treatment for patients in Europe with this type of advanced breast cancer
 
AstraZeneca's camizestrant in combination with a cyclin-dependent kinase (CDK) 4/6 inhibitor (palbociclib, ribociclib or abemaciclib) has been recommended for approval in the European Union (EU) for the treatment of adult patients with estrogen receptor (ER)-positive, HER2-negative locally advanced or metastatic breast cancer upon detection of ESR1 mutation and without disease progression during 1st-line endocrine therapy in combination with a CDK4/6 inhibitor.
 
The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) based its positive opinion on the results from the pivotal SERENA-6 Phase III trial, which were presented at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting and simultaneously published in The New England Journal of Medicine.1
 
 
In a planned interim analysis, the camizestrant combination reduced the risk of disease progression or death by 56% versus standard-of-care treatment with an aromatase inhibitor (AI) (anastrozole or letrozole) in combination with a CDK4/6 inhibitor (based on a hazard ratio [HR] of 0.44; 95% confidence interval [CI] 0.31-0.60; p<0.00001; median progression-free survival (PFS) 16.0 versus 9.2 months). Data for the key secondary endpoints of time to second disease progression (PFS2) and overall survival (OS) were immature at the time of the interim analysis, however a subsequent pre-planned analysis demonstrated a statistically significant and clinically meaningful PFS2 benefit of 25.7 months versus 19.1 months in favour of the camizestrant combination (HR: 0.63; 95% CI: 0.46-0.86; p = 0.00373) and OS continued to mature in favour of the camizestrant combination (HR: 0.87; 95% CI: 0.57-1.30). The trial will continue to assess OS as a key secondary endpoint. 
 
François-Clément Bidard, MD, PhD, Professor of Medical Oncology at Institut Curie & Versailles University (Paris/Saclay), France, and co-principal investigator for the SERENA-6 trial, said: "This recommendation represents an important step forward for patients with advanced breast cancer in Europe and a milestone in the adoption of new treatment strategies. There is a need for new treatments that delay disease progression in the 1st-line setting, after which the cancer becomes harder to treat, and a patient's quality of life may decline. Through prompt intervention with the camizestrant combination to treat emergence of resistance before it causes disease progression and deterioration of quality of life, we are able to extend the benefit of 1st-line treatment and optimise outcomes."
 
Susan Galbraith, Executive Vice President, Oncology Haematology R&D, AstraZeneca, said: "This decision from the EU's CHMP is a vote of confidence in SERENA-6, the first pivotal trial to demonstrate the clinical value of monitoring circulating tumour DNA to detect emerging endocrine resistance and guide a change of therapeutic strategy in the 1st-line setting. If approved, camizestrant would be the first and only next-generation oral SERD and complete ER antagonist for use in combination with widely approved CDK4/6 inhibitors in this setting, reinforcing the practice-changing potential of this approach to advance patient outcomes and evolve the clinical landscape."
 
The safety profile of camizestrant in combination with palbociclib, ribociclib or abemaciclib in the SERENA-6 trial was consistent with the known safety profile of each medicine. No new safety concerns were identified and discontinuations were very low and similar in both arms.1
 
SERENA-6 is the first global, double-blind, registrational Phase III trial to use a circulating tumour DNA (ctDNA)-guided approach to detect the emergence of endocrine resistance and inform a switch in therapy before disease progression. The innovative trial design used ctDNA monitoring via a blood test at the time of routine tumour scans every two to three months to identify patients for early signs of endocrine resistance via the emergence of ESR1 mutations. Following detection of an ESR1 mutation without disease progression, the endocrine therapy of patients was switched to camizestrant from ongoing treatment with an AI, while continuing combination with the same CDK4/6 inhibitor.
 
The camizestrant combination is approved in the United Arab Emirates and Saudi Arabia in hormone receptor (HR)-positive, HER2-negative advanced breast cancer patients whose tumours have an emergent ESR1 mutation based on the results of the SERENA-6 Phase III trial.
 
Regulatory applications for camizestrant in this setting are currently under review in the US, Japan and several other countries.
 
Notes
 
HR-positive breast cancer
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 2022, with more than 665,000 deaths globally.2 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.3 
 
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.3 More than 97% of HR-positive breast cancer tumours are ER-positive.4,5 ERs often drive the growth of HR-positive breast cancer cells.6
 
Globally, approximately 200,000 patients with HR-positive breast cancer are treated with a medicine in the 1st-line setting; most frequently with endocrine therapies that target ER-driven disease, which are often paired with CDK4/6 inhibitors.7-9 However, resistance to these therapies develops in many patients.9 Once this occurs, treatment options are limited and survival rates are low with approximately 36% of patients anticipated to live beyond five years after diagnosis.3,9
 
Mutations in the ESR1 gene are a key driver of endocrine resistance and are associated with poor outcomes, emerging during treatment of the disease and becoming more prevalent as the disease progresses.10,11 Approximately 30% of patients with endocrine sensitive HR-positive disease develop ESR1 mutations during 1st-line treatment before disease progression.7
 
The optimisation of endocrine therapy and overcoming resistance to enable patients to continue benefiting from these treatments, as well as identifying new therapies for those who are less likely to benefit, are active areas of focus for breast cancer research. 
 
SERENA-6
SERENA-6 is a Phase III, double-blind, randomised trial evaluating the efficacy and safety of camizestrant in combination with a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) versus treatment with an AI (anastrozole or letrozole) in combination with a CDK4/6 inhibitor (palbociclib, ribociclib or abemaciclib) in patients with HR-positive, HER2-negative advanced breast cancer (patients with either locally advanced disease, or metastatic disease) whose tumours have an emergent ESR1 mutation.
 
The global trial enrolled 315 adult patients with histologically confirmed HR-positive, HER2-negative advanced breast cancer, undergoing treatment with an AI in combination with a CDK4/6 inhibitor as 1st-line treatment. The primary endpoint of the SERENA-6 trial is PFS as assessed by investigator, with secondary endpoints including OS, and PFS2 by investigator assessment.
 
Camizestrant
Camizestrant is an investigational, potent, next-generation oral selective estrogen receptor degrader (SERD) and complete ER antagonist that is currently in Phase III trials for the treatment of HR-positive breast cancer.
 
AstraZeneca's broad, robust and innovative clinical development programme, including the SERENA-6, SERENA-4, CAMBRIA-1 and CAMBRIA-2 trials, is evaluating the safety and efficacy of camizestrant when used as a monotherapy or in combination with CDK4/6 inhibitors to address a number of areas of unmet need in HR-positive, HER2-negative breast cancer.
 
Camizestrant has demonstrated anti-cancer activity across a range of preclinical models, including those with ER-activating mutations. In the SERENA-2 Phase II trial, camizestrant demonstrated a statistically significant and clinically meaningful improvement in PFS versus Faslodex (fulvestrant) in the overall trial population, including in patients with ESR1 tumour mutations irrespective of prior treatment with CDK4/6 inhibitors in patients with ER-positive locally advanced or metastatic breast cancer, previously treated with endocrine therapy. The SERENA-1 Phase I trial demonstrated that camizestrant is well tolerated and has a promising anti-tumour profile when administered alone or in combination with palbociclib, ribociclib and abemaciclib; three widely used CDK4/6 inhibitors.
 
AstraZeneca in breast cancer
Driven by a growing understanding of breast cancer biology, AstraZeneca is challenging, and redefining, the current clinical paradigm for how breast cancer is classified and treated to deliver even more effective treatments to patients in need - with the bold ambition to one day eliminate breast cancer as a cause of death.
 
AstraZeneca has a comprehensive portfolio of approved and promising compounds in development that leverage different mechanisms of action to address the biologically diverse breast cancer tumour environment.
 
With Enhertu (trastuzumab deruxtecan), a HER2-directed antibody drug conjugate (ADC), AstraZeneca and Daiichi Sankyo are aiming to improve outcomes in previously treated HER2-positive, HER2-low and HER2-ultralow metastatic breast cancer, and are exploring its potential in earlier lines of treatment and in new breast cancer settings.
 
In HR-positive breast cancer, AstraZeneca continues to improve outcomes with foundational medicines Faslodex and Zoladex (goserelin) and aims to reshape the HR-positive space with first-in-class AKT inhibitor, Truqap, the TROP-2-directed ADC, Datroway (datopotamab deruxtecan) and next-generation oral SERD and potential new medicine camizestrant.
 
PARP inhibitor Lynparza (olaparib) is a targeted treatment option that has been studied in early and metastatic breast cancer patients with an inherited BRCA mutation. AstraZeneca with MSD (Merck & Co., Inc. in the US and Canada) continue to research Lynparza in these settings. AstraZeneca is also exploring the potential of saruparib, a potent and selective inhibitor of PARP1, in combination with camizestrant in BRCA-mutated, HR-positive, HER2-negative advanced breast cancer.
 
To bring much-needed treatment options to patients with triple-negative breast cancer, an aggressive form of breast cancer, AstraZeneca is collaborating with Daiichi Sankyo to evaluate the potential of Datroway alone and in combination with immunotherapy Imfinzi (durvalumab).
 
AstraZeneca in oncology
AstraZeneca is leading a revolution in oncology with the ambition to provide cures for cancer in every form, following the science to understand cancer and all its complexities to discover, develop and deliver life-changing medicines to patients.
 
The Company's focus is on some of the most challenging cancers. It is through persistent innovation that AstraZeneca has built one of the most diverse portfolios and pipelines in the industry, with the potential to catalyse changes in the practice of medicine and transform the patient experience.
 
AstraZeneca has the vision to redefine cancer care and, one day, eliminate cancer as a cause of death.
 
AstraZeneca
AstraZeneca (LSE/STO/NYSE: AZN) is a global, science-led biopharmaceutical company that focuses on the discovery, development, and commercialisation of prescription medicines in Oncology, Rare Disease, and BioPharmaceuticals, including Cardiovascular, Renal & Metabolism, and Respiratory & Immunology. Based in Cambridge, UK, AstraZeneca's innovative medicines are sold in more than 125 countries and used by millions of patients worldwide. Please visit astrazeneca.com and follow the Company on Social Media @AstraZeneca.
 
Contacts
For details on how to contact the Investor Relations Team, please click here. For Media contacts, click here.
 
References
1.   Bidard FC, et al. First-Line Camizestrant for Emerging ESR1-Mutated Advanced Breast Cancer. N Engl J Med 2025; DOI: 10.1056/NEJMoa2502929.
2.   Bray F, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin. 2024; 1- 35. DOI:10.3322/caac.21834.
3.   National Cancer Institute. Cancer Stat facts: Female breast cancer subtypes. Available at: https://seer.cancer.gov/statfacts/html/breast-subtypes.html. Accessed May 2026.
4.   Bae S, et al. Poor prognosis of single hormone receptor positive breast cancer: similar outcome as triple-negative breast cancer. BMC Cancer. 2015; 15:138.
5.   Cserni G, et al. Estrogen Receptor Negative and Progesterone Receptor Positive Breast Carcinomas-How Frequent are they? Pathol. Oncol. Res. 2011; 17:663-668.
6.   Scabia V, et al. Estrogen receptor positive breast cancers have patient specific hormone sensitivities and rely on progesterone receptor. Nat Commun. 2022; 10.1038/s41467-022-30898-0.
7.   Cerner CancerMPact database. Accessed May 2026.
8.   Lin M, et al. Comparative Overall Survival of CDK4/6 Inhibitors Plus Endocrine Therapy vs. Endocrine Therapy Alone for Hormone receptor-positive, HER2-negative metastatic breast cancer. J Cancer. 2020; 10.7150/jca.48944.
9.   Lloyd M R, et al. Mechanisms of Resistance to CDK4/6 Blockade in Advanced Hormone Receptor-positive, HER2-negative Breast Cancer and Emerging Therapeutic Opportunities. Clin Cancer Res. 2022; 28(5):821-30.
10.  Brett O, et al. ESR1 mutation as an emerging clinical biomarker in metastatic hormone receptor-positive breast cancer. Breast Cancer Res. 2021; 23:85.
11.  Zundelevich A, et al. ESR1 mutations are frequent in newly diagnosed metastatic and loco-regional recurrence of endocrine-treated breast cancer and carry worse prognosis. Breast Cancer Res. 2020; 22:16.
 
​​Matthew Bowden​
​​Company Secretary​
​​AstraZeneca PLC​
 
SIGNATURES
 
Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.
 
 
AstraZeneca PLC
 
 
Date: 26 May 2026
 
 
By: /s/ Matthew Bowden
 
Name: Matthew Bowden
 
Title: Company Secretary

FAQ

What did AstraZeneca (AZN) announce about camizestrant in Europe?

AstraZeneca reported that the EU’s CHMP issued a positive opinion recommending approval of camizestrant plus a CDK4/6 inhibitor for ER-positive, HER2-negative advanced breast cancer with emergent ESR1 mutation, based on Phase III SERENA-6 results showing a substantial progression-free survival benefit.

How effective was AstraZeneca’s camizestrant in the SERENA-6 trial?

In SERENA-6, camizestrant plus a CDK4/6 inhibitor reduced the risk of disease progression or death by 56% versus aromatase inhibitor plus CDK4/6 inhibitor, improving median progression-free survival to 16.0 months from 9.2 months, demonstrating a clinically meaningful efficacy advantage in this patient group.

What secondary outcomes were reported for SERENA-6 in AstraZeneca’s 6-K?

A later pre-planned analysis showed time to second disease progression of 25.7 months with camizestrant combination versus 19.1 months for control, with a hazard ratio of 0.63. Overall survival data continued to mature in favour of camizestrant, with a reported hazard ratio of 0.87.

What is the safety profile of camizestrant plus CDK4/6 inhibitors?

The safety profile of camizestrant combined with palbociclib, ribociclib or abemaciclib in SERENA-6 was consistent with the known safety of each medicine. No new safety concerns were identified, and discontinuation rates were very low and similar between the camizestrant and control treatment arms.

Where is AstraZeneca’s camizestrant already approved or under review?

Camizestrant is approved in the United Arab Emirates and Saudi Arabia for HR-positive, HER2-negative advanced breast cancer with emergent ESR1 mutation, based on SERENA-6. Regulatory applications in the same setting are under review in the US, Japan and several other countries, reflecting a global development strategy.

What breast cancer subtype is targeted by AstraZeneca’s camizestrant?

Camizestrant targets hormone receptor-positive, HER2-negative advanced breast cancer, particularly tumours that are ER-positive with emergent ESR1 mutations. This subtype represents the most common form of breast cancer, where resistance to standard endocrine therapy and CDK4/6 inhibitor combinations is a major clinical challenge.