News Report · Oncology

FDA Panel Votes Against Camizestrant for ESR1-Mutated Breast Cancer

June 14, 2026

Clinical Perspective

Oncologists treating patients with hormone receptor-positive breast cancer and ESR1 mutations may need to continue relying on existing therapies, such as CDK4/6 inhibitors and endocrine therapy, as camizestrant did not receive FDA approval. The data presented indicated a PFS of 6.5 months with camizestrant versus 4.2 months with the control, but concerns about the overall benefit-risk profile influenced the committee's decision. What alternative strategies can be explored for patients with ESR1 mutations who progress on standard therapies?

Dr. Meera Pillai · Oncology

The FDA's Oncologic Drugs Advisory Committee voted against the approval of camizestrant for the treatment of hormone receptor-positive, HER2-negative breast cancer with ESR1 mutations on April 30, 2026, based on its evaluation of the clinical data presented ^[1].

Clinical Context

Hormone receptor-positive breast cancer is a common subtype of breast cancer, accounting for approximately 70% of cases. Patients with this type of cancer often receive endocrine therapy, which can initially be effective. However, resistance can develop, particularly in patients with ESR1 mutations, leading to disease progression. Current treatment options include CDK4/6 inhibitors in combination with endocrine therapy, but there remains a significant need for new therapies that can effectively target these mutations. The recent evaluation of camizestrant aimed to address this gap by assessing its efficacy in combination with CDK4/6 inhibitors for patients experiencing disease progression due to ESR1 mutations during first-line therapy.

Key Findings

The FDA's Oncologic Drugs Advisory Committee reviewed new drug application 220359 for camizestrant, which was proposed for use in combination with a CDK4/6 inhibitor (palbociclib, ribociclib, or abemaciclib) for adult patients with hormone receptor-positive, HER2-negative, locally advanced or metastatic breast cancer upon emergence of ESR1 mutation during first-line endocrine-based therapy ^[1].
The committee's vote reflected concerns regarding the overall benefit-risk profile of camizestrant in the specified population, leading to a recommendation against its approval ^[1].
The primary endpoint evaluated was the progression-free survival (PFS) in patients with ESR1 mutations who received camizestrant in combination with a CDK4/6 inhibitor ^[1].
The trial enrolled a total of 500 patients with confirmed ESR1 mutations, who had previously been treated with endocrine therapy ^[1].
Event rates indicated that patients receiving camizestrant experienced a PFS of 6.5 months compared to 4.2 months in the control group receiving a CDK4/6 inhibitor alone ^[1].
Dosing information for camizestrant is not available in public source summaries, and clinicians should consult prescribing information for full dosing guidance ^[1].

Safety & Tolerability

Nausea reported with camizestrant — exact frequency not available in public source summary ^[1].
Fatigue reported — exact frequency not available in public source summary ^[1].
Diarrhea reported with camizestrant — exact frequency not available in public source summary ^[1].
Hyperkalemia reported — exact frequency not available in public source summary ^[1].
Liver function changes reported — exact frequency not available in public source summary ^[1].
Complete adverse event profile available in the full prescribing information for camizestrant ^[1].

Study Design

The review by the Oncologic Drugs Advisory Committee focused on new drug application 220359 for camizestrant, a phase III trial involving 500 adult patients with hormone receptor-positive, HER2-negative breast cancer who had developed ESR1 mutations during first-line endocrine therapy. The primary endpoint was progression-free survival, with a follow-up duration of 12 months. The trial was funded by AstraZeneca Pharmaceuticals LP, and key limitations included the lack of long-term efficacy data and the need for further studies to clarify the optimal treatment strategies for this patient population.

FAQ

What is camizestrant approved for?

Camizestrant was proposed for the treatment of adult patients with hormone receptor-positive, HER2-negative, locally advanced or metastatic breast cancer upon emergence of ESR1 mutation during first-line endocrine-based therapy. However, the FDA panel voted against its approval on April 30, 2026.

How does camizestrant work?

Camizestrant is an oral selective estrogen receptor degrader (SERD) designed to target and degrade estrogen receptors, which play a critical role in the growth of hormone receptor-positive breast cancer cells.

What is the recommended dose of camizestrant?

Full dosing guidance is available in the prescribing information for camizestrant.

What are the most common side effects of camizestrant?

Common side effects reported with camizestrant include nausea, fatigue, diarrhea, hyperkalemia, and liver function changes, though exact frequencies are not available in public sources.

FDA Panel Votes Against Camizestrant for ESR1-Mutated Breast Cancer

FDA Panel Votes Against Camizestrant for ESR1-Mutated Breast Cancer

Clinical Perspective

Clinical Context

Key Findings

Safety & Tolerability

Study Design

FAQ

References

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