Camizestrant Extends PFS vs Fulvestrant in Post-Menopausal ER+ Locally Advanced mBC

The risk of progression or death in post-menopausal patients with estrogen receptor-positive locally advanced or metastatic breast cancer was reduced with camizestrant in the SERENA-2 study.

Camizestrant (AZD9833) demonstrated a clinically meaningful and statistically significant improvement in progression-free survival (PFS) compared with fulvestrant (Faslodex) when administered at both the 75 mg and 150 mg dose levels in patients with post-menopausal patients with estrogen receptor (ER)-positive locally advanced or metastatic breast cancer, previously treated with endocrine therapy for advanced disease.1

These results announced in a press release by AstraZeneca are from the phase 2 SERENA-2 clinical trial (NCT04214288). In the study, camizestrant was well-tolerated and showed a safety profile that is consistent with prior studies. No new safety signals were observed during the study.

“The results from SERENA-2 show that camizestrant provides a significant improvement in progression-free survival compared with fulvestrant, which has been used to treat patients with HR-positive breast cancer for almost 20 years. These results are meaningful, highlighting the potential of this next-generation oral SERD and supporting the ongoing research program,” said Mafalda Oliveira, MD, PhD, a medical oncologist at the Medical Department of the Vall d'Hebron University Hospital and Vall d’Hebron Institute of Oncology in Barcelona, Spain, and lead investigator of SERENA-2, in the press release.

SERENA-2 is a randomized, open-label, parallel-group, multicenter study. Approximately 240 post-menopausal women with histologically or cytologically confirmed metastatic or loco-regionally recurrent ER-positive HER2-negative breast cancer before randomization were included. Following a screening visit to confirm their eligibility for the trial, patients were randomized in a 1:1:1:1 ratio to receive 1 of 3 camizestrant dose levels in arms A to C or fulvestrant 500 mg.2

Aside from PFS, investigators of the study assessed secondary end points including, objective response rate, duration of response, the percentage change in tumor size at 16 weeks, overall survival, clinical benefit rate at 24 weeks, plasma concentrations of camizestrant, percent change from baseline in ER and PgR expression and Ki67 labeling index, and changes from baseline in health-related quality of life.

Full results from SERENA-2 will be presented at an upcoming medical meeting.

“Our goal with our next-generation oral SERD camizestrant is to improve on currently available endocrine therapies for patients with HR-positive breast cancer in early and metastatic disease. The exciting efficacy and compelling safety results from the SERENA-2 trial underscore the potential for camizestrant to achieve this goal in patients with ER-driven breast cancer and we look forward to advancing our comprehensive phase 3 clinical program for camizestrant," said Susan Galbraith, EVP, Oncology R&D, AstraZeneca, the press release.

Camizestrant is currently being studied in the combination with the CDK4/6 inhibitors palbociclib (Ibrance) or abemaciclib (Verzenio) for the treatment of patients with HR-positive metastatic breast cancer who have detectable ESR1 mutations on frontline treatment in SERENA-6 (NCT0496493). The agent is also in combination with palbociclib alone for the treatment of patients with HR-positive, locally advanced or metastatic breast cancer from the start of therapy in the first-line setting in SERENA-4 (NCT04711252).


1. Camizestrant significantly improved progression-free survival vs. faslodex in SERENA-2 Phase II trial in advanced ER-positive breast cancer. News release. AstraZeneca. October 26, 2022. Accessed October 26, 2022.

2. A comparative study of AZD9833 versus fulvestrant in women with advanced ER-positive HER2-negative breast cancer (SERENA-2). Updated October 20, 2022. Accessed October 26, 2022.