SERENA-4 Trial: Camizestrant Misses 1L PFS in ER+ Breast Cancer

At a Glance

SERENA-4 Key Takeaways

Design

Global, randomized, double-blind Phase III: camizestrant + palbociclib vs anastrozole + palbociclib, first-line ER-positive/HER2-negative advanced breast cancer; 1,371 adults, Stage IV de novo or recurrent, no prior systemic therapy for advanced disease. (AstraZeneca statement, Sept 11, 2026 · ClinicalTrials.gov)

Result — primary endpoint not met

A numerical improvement in progression-free survival was observed with camizestrant + palbociclib vs anastrozole + palbociclib, but the difference did not reach statistical significance. No efficacy figures (medians, hazard ratio, p-value) have been released; detailed results are expected at a later date. (AstraZeneca statement, Sept 11, 2026)

Safety

Safety was consistent with the known profile of each medicine; no new safety concerns identified. (AstraZeneca statement, Sept 11, 2026)

Class context

SERENA-4 is the second Phase III miss for an upfront oral SERD in unselected 1L ER+ disease, after persevERA (giredestrant). In Dr. Sammons’ words below: “ESR1 mutation still reigns as biomarker for SERDs in advanced disease.”

Regulatory

⚠ Camizestrant (Etcamah) retains its US accelerated approval — granted September 2026 on SERENA-6 — with a CDK4/6 inhibitor for HR+/HER2− advanced breast cancer that develops an ESR1 mutation during 1L endocrine therapy. The unselected first-line use studied in SERENA-4 is investigational and not approved.

Who's Talking

KOL Voices on SERENA-4

Paolo Tarantino

@PTarantinoMD

20,385 impressions

Dr Sarah Sammons

@drsarahsam

1,695 impressions

Yakup Ergün

@dr_yakupergun

1,123 impressions

Mitsuo Terada, MD, PhD

@MamMa_mimumemo

3,465 impressions

Harold J. Burstein, MD, PhD, FASCO

@DrHBurstein

4,088 impressions

Yüksel Ürün

@DrYukselUrun

459 impressions

Jame Abraham, MD, FACP

@jamecancerdoc

301 impressions

Verbatim Reactions

The Readout, in the Physicians' Own Words

Paolo Tarantino@PTarantinoMD

𝕏

BREAKING: SERENA-4 is negative. Similar to giredestrant, camizestrant did not improve outcomes vs AI when combined to CDK4/6i in the 1L setting. Its role remains confined to pts with ESR1 mutations, which seems to be the sweet spot for oral SERDs in MBC. https://t.co/d4g58bmmzM https://t.co/7RhKh2z3Ll

20,385 views141 likes43 RT2026-09-11

Harold J. Burstein, MD, PhD, FASCO@DrHBurstein

𝕏

An unusual 10 day span for a new drug with one approval requiring confirmation and a second study that is negative https://t.co/ajR1Bks4G2

4,088 views0 likes0 RT2026-09-11

Mitsuo Terada, MD, PhD@乳腺科医@MamMa_mimumemo

𝕏

カミゼストラントのSERENA-4がネガティブ… giredestrantのpersevERAに続き、1st line oral SERD+CDK4/6阻害薬がAI+CDK4/6iに勝てず。 oral SERDは今あるESR1変異には効いても、ESR1変異を出さないようにする戦略には向いてないってことだろうか。それはそれで使い所は整理されるのかもしれないけど。 https://t.co/M3rNNeaGi0

3,465 views28 likes3 RT2026-09-11

Dr Sarah Sammons@drsarahsam

𝕏

Second reportedly negative upfront SERD trial in ER+ HER2- MBC negative. ESR1 mutation still reigns as biomarker for SERDs in advanced disease. Update on SERENA-4 Phase III trial of Etcamah in combination with palbociclib in upfront 1st-line https://t.co/0VQRM8fVbH

1,695 views22 likes4 RT2026-09-11

OncLive.com@OncLive

𝕏

Camizestrant plus palbociclib did not significantly improve progression-free survival vs anastrozole plus palbociclib in the first-line SERENA-4 trial. #bcsm #oncology https://t.co/r23YAfiVHk

1,134 views6 likes4 RT2026-09-12

Yakup Ergün@dr_yakupergun

𝕏

🚨⁉️ Following persevERA, SERENA-4 is also negative: the strategy of using an oral SERD from day one in an unselected patient population did not work. Precision medicine means treating according to tumor biology, not giving the same treatment to everyone. A note to pharmaceutical companies: In trying to broaden indications, these negative results may also make us question your previous approvals. The place of oral SERDs is in ESR1-mutant disease. The lidERA study needs to be discussed separately. Since there was no CDK4/6 inhibitor, if endocrine blockade was insufficient, it may have revealed a difference in the ET backbone. However, once blockade is strengthened with a CDK4/6 inhibitor, the added benefit of oral SERDs probably becomes less meaningful. Of course, this is just one of the possible hypotheses. I look forward to seeing the full datasets.

1,123 views12 likes2 RT2026-09-12

がんナビ通信@cancer_navi

𝕏

#乳がんの試験で残念な結果。ER陽性HER2陰性進行乳がんの1次治療を検証したSERENA-4試験で、#カミゼストラント＋パルボシクリブは標準治療に比べ無増悪生存期間の数値は改善したものの、有意な延長を示せませんでした。 https://t.co/K7CvmrPzTj

916 views13 likes2 RT2026-09-12

Yüksel Ürün@DrYukselUrun

𝕏

Same class ≠ same drug. Same target ≠ same outcome. SERENA-4 is another reminder of why we need clinical trials: in medicine, biological plausibility is a hypothesis. Evidence is the answer. In oncology, “it should work” is never enough. https://t.co/9VGNpogNUs

459 views0 likes0 RT2026-09-12

Jame Abraham, MD, FACP@jamecancerdoc

𝕏

SERENA-4 trial did not meet primary objective of statistically significant improvement in progression-free survival, however a numerical improvement was observed https://t.co/fzNuYclSVX https://t.co/16kvrp7TQZ

301 views0 likes0 RT2026-09-12

Company Statement

Topline Announcement — September 11, 2026

PRIMARY ENDPOINT NOT MET — camizestrant + palbociclib, 1L ER+/HER2− advanced breast cancer

AstraZeneca announced that SERENA-4 did not meet its primary endpoint of progression-free survival; a numerical improvement was observed but did not reach statistical significance. Safety was consistent with the known profile of each medicine. Susan Galbraith, EVP Oncology Haematology R&D, AstraZeneca: “Whilst we are disappointed by the SERENA-4 outcome, it sharpens our focus on maximising the number of patients who can benefit from Etcamah today.”

Source: OncoDaily coverage of the AstraZeneca statement ↗ ClinicalTrials.gov NCT04711252 ↗

How This Page Is Built

Methodology

Verbatim Quotes

Every physician post appears exactly as written on X — never paraphrased or truncated.

Sourced Claims

Every factual claim traces to the AstraZeneca statement, ClinicalTrials.gov, or the cited coverage. No efficacy numbers appear because none have been released.

Approved vs Investigational

Camizestrant's ESR1-guided accelerated approval (SERENA-6) is clearly separated from the unapproved 1L unselected setting studied here.

Live Tracking

This page updates as detailed SERENA-4 data are presented and as the KOL discussion evolves.

Questions & Answers

SERENA-4 FAQ

What is the SERENA-4 trial?

SERENA-4 (NCT04711252) is a global, randomized, double-blind Phase III trial of camizestrant (Etcamah, AstraZeneca) plus palbociclib versus anastrozole plus palbociclib as first-line treatment for ER-positive, HER2-negative advanced breast cancer. It enrolled 1,371 adults with Stage IV de novo or recurrent disease and no prior systemic therapy for advanced disease.

What did SERENA-4 show?

On September 11, 2026, AstraZeneca announced that SERENA-4 did not meet its primary endpoint: a numerical improvement in progression-free survival was observed with camizestrant plus palbociclib versus anastrozole plus palbociclib, but the difference did not reach statistical significance. Detailed efficacy figures have not yet been released.

Were there new safety concerns?

No. AstraZeneca stated the safety profile of camizestrant plus palbociclib in SERENA-4 was consistent with the known profile of each medicine, with no new safety concerns identified.

Is camizestrant still FDA approved?

Yes — the SERENA-4 result does not change camizestrant's existing US approval. Etcamah (camizestrant) holds accelerated approval, based on SERENA-6, in combination with a CDK4/6 inhibitor for HR-positive, HER2-negative advanced breast cancer that develops an ESR1 mutation during first-line endocrine therapy. First-line use in unselected (ESR1 wild-type) patients, as studied in SERENA-4, is investigational and not approved.

What does the result mean for oral SERDs in first line?

SERENA-4 is the second Phase III miss for an upfront oral SERD in unselected first-line ER-positive advanced breast cancer, after persevERA (giredestrant). Physicians in the discussion on this page note that the ESR1 mutation remains the biomarker that defines where these agents work.

Every Tracked Post

KOL Sentiment

KOL	Comment (verbatim)	Sentiment
Paolo Tarantino	BREAKING: SERENA-4 is negative. Similar to giredestrant, camizestrant did not improve outcomes vs AI when combined to CDK4/6i in the 1L setting. Its role remains confined to pts with ESR1 mutations, which seems to be the sweet spot for oral SERDs in MBC. https://t.co/d4g58bmmzM https://t.co/7RhKh2z3Ll	NEUTRAL
Mitsuo Terada, MD, PhD@乳腺科医	カミゼストラントのSERENA-4がネガティブ… giredestrantのpersevERAに続き、1st line oral SERD+CDK4/6阻害薬がAI+CDK4/6iに勝てず。 oral SERDは今あるESR1変異には効いても、ESR1変異を出さないようにする戦略には向いてないってことだろうか。それはそれで使い所は整理されるのかもしれないけど。 https://t.co/M3rNNeaGi0	NEUTRAL
Dr Sarah Sammons	Second reportedly negative upfront SERD trial in ER+ HER2- MBC negative. ESR1 mutation still reigns as biomarker for SERDs in advanced disease. Update on SERENA-4 Phase III trial of Etcamah in combination with palbociclib in upfront 1st-line https://t.co/0VQRM8fVbH	NEUTRAL
OncLive.com	Camizestrant plus palbociclib did not significantly improve progression-free survival vs anastrozole plus palbociclib in the first-line SERENA-4 trial. #bcsm #oncology https://t.co/r23YAfiVHk	NEUTRAL
Yakup Ergün	🚨⁉️ Following persevERA, SERENA-4 is also negative: the strategy of using an oral SERD from day one in an unselected patient population did not work. Precision medicine means treating according to tumor biology, not giving the same treatment to everyone. A note to pharmaceutical companies: In trying to broaden indications, these negative results may also make us question your previous approvals. The place of oral SERDs is in ESR1-mutant disease. The lidERA study needs to be discussed separately. Since there was no CDK4/6 inhibitor, if endocrine blockade was insufficient, it may have revealed a difference in the ET backbone. However, once blockade is strengthened with a CDK4/6 inhibitor, the added benefit of oral SERDs probably becomes less meaningful. Of course, this is just one of the possible hypotheses. I look forward to seeing the full datasets.	NEUTRAL
がんナビ通信	#乳がんの試験で残念な結果。ER陽性HER2陰性進行乳がんの1次治療を検証したSERENA-4試験で、#カミゼストラント＋パルボシクリブは標準治療に比べ無増悪生存期間の数値は改善したものの、有意な延長を示せませんでした。 https://t.co/K7CvmrPzTj	NEUTRAL
Harold J. Burstein, MD, PhD, FASCO	An unusual 10 day span for a new drug with one approval requiring confirmation and a second study that is negative https://t.co/ajR1Bks4G2	NEUTRAL
Yüksel Ürün	Same class ≠ same drug. Same target ≠ same outcome. SERENA-4 is another reminder of why we need clinical trials: in medicine, biological plausibility is a hypothesis. Evidence is the answer. In oncology, “it should work” is never enough. https://t.co/9VGNpogNUs	NEUTRAL
Jame Abraham, MD, FACP	SERENA-4 trial did not meet primary objective of statistically significant improvement in progression-free survival, however a numerical improvement was observed https://t.co/fzNuYclSVX https://t.co/16kvrp7TQZ	NEUTRAL

SERENA-4 Trial