Camizestrant Meets PFS End Point Vs Fulvestrant in ER+ Advanced/Metastatic Breast Cancer

Oral selective estrogen receptor degrader camizestrant elicited a statistically significant and clinically meaningful progression-free survival benefit compared with fulvestrant among patients with estrogen receptor–positive locally advanced or metastatic breast cancer.

Results from the SERENA-2 phase 2 trial (NCT04214288) indicated that camizestrant met the primary end point of improved progression-free survival (PFS) vs fulvestrant (Faslodex) in patients with estrogen receptor (ER)–positive locally advanced or metastatic breast cancer, according to a press release from AstraZeneca.

The improvement was found to be both statistically significant and clinically meaningful and was observed among patients treated at a dose of 75 mg and 150 mg, respectively. Camizestrant was well tolerated and produced a safety profile that was consistent with data from previous studies, demonstrating no new safety signals. Findings from the SERENA-2 trial will be presented at an upcoming medical meeting.

“The results from SERENA-2 show that camizestrant provides a significant improvement in progression-free survival compared to fulvestrant, which has been used to treat patients with [hormone receptor–positive] breast cancer for almost twenty years,” lead investigator Mafalda Oliveira, MD, PhD, attending physician of the Department of Medical Oncology, Breast Cancer Group at Vall d’Hebron Institute of Oncology in Barcelona, Spain, said in the press release. “These results are meaningful, highlighting the potential of this next-generation oral [selective estrogen receptor degrader (SERD)] and supporting the ongoing research program.”

Camizestrant is an oral SERD and ER antagonist that has previously shown efficacy in clinical settings including the phase 1 SERENA-1 trial (NCT03616587), which assessed the agent’s tolerability and anti-tumor profile among women with advanced breast cancer alone and in combination with palbociclib (Ibrance). Treatment combinations with other agents are still being explored in the SERENA-1 study.

The randomized, open-label, parallel group phase 2 SERENA-2 trial was designed to compare the efficacy and safety of oral camizestrant at different dose levels with intramuscular fulvestrant in patients with advanced ER-positive, HER2-negative breast cancer. Two hundred and forty patients were randomly assigned to receive either 75 mg or 150 mg of oral camizestrant or a 500 mg intramuscular injection of fulvestrant until disease progression.

Secondary end points of the trial included investigator-assessed objective response rate, duration of response per RECIST v1.1 criteria, overall survival, clinical benefit rate, plasma concentrations of camizestrant, changes from baseline in ER and progesterone receptor expression, and changes from baseline in health-related quality of life for up to approximately 3 years.

Post-menopausal patients at least 18 years old with metastatic or locally recurrent ER-positive, HER2-negative adenocarcinoma of the breast were eligible to enroll on the trial. Additional inclusion criteria included having radiological progression on or after last systemic therapy prior to starting study treatment, having at least 1 accurately measurable lesion at baseline, and an ECOG/World Health Organization performance status of 0 or 1. Moreover, patients were included if they had disease recurrence or progression on at least 1 line of endocrine therapy and had no more than 1 line of endocrine therapy and 1 line of chemotherapy for advanced disease.

Patients were excluded if they had received any cytotoxic chemotherapy, investigational agents, or other anti-cancer treatment for breast cancer from a previous regimen or clinical study within 14 days of the first dose of study treatment.

Reference

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 28, 2022. https://bit.ly/3WaeWwT