On September 4, 2026 the FDA granted accelerated approval to Etcamah (camizestrant, AstraZeneca) plus a CDK4/6 inhibitor for HR+/HER2− advanced breast cancer on detection of an ESR1 mutation during first-line AI + CDK4/6i therapy. The FDA's Oncology Center of Excellence Director called it “the first FDA approval of a cancer therapy guided by the detection of a resistance mutation in circulating tumor DNA (ctDNA) before imaging tests show that the disease is progressing.” Four months earlier, the FDA's advisory committee voted 6–3 against the strategy. Several oncologists say, on the record, that they still agree with that vote. Every quote below is verbatim and linked.
Sources: the FDA press announcement, the FDA approval notice, and the complete record (same-day physician reactions, every data cut with source labels, the full regulatory timeline) on the SERENA-6 trial profile.
Presented with an AI narrator; every quote in the briefing is verbatim from the named physicians’ public posts.
The clearest KOL summary of the FDA's position came from Dr. Rishabh Jain, whose six-problem breakdown of the briefing documents circulated widely after the vote:
This is really the takeaway from today's #ODAC vote 6-3 against recommending approval of #camizestrant at this time based on #SERENA6. We don't know yet what the benefit of an early switch in the absence of radiographic PD is long term. PFS2 as designed here doesn't answer.
PFS nearly doubled. Still not enough. No OS, PFS2 confounded, clinical meaningfulness unproven. Is ctDNA-guided pre-emptive switching dead on arrival? Or is FDA just too conservative? 🧵 #ODAC #SERENA6 #ESR1 #Oncology @ESMO_Open @myesmo
Dr. Hamilton's post-ODAC takeaway (above) drew a conversation between oncologists and patient advocates. The exchange, verbatim:
@ErikaHamilton9 @PTarantinoMD Do you think if crossover allowed or including QoL measures as 1° or 2° endpoint would have made a difference? I sure would have pushed for that if I, as someone #NotDeadYet w/ MBC, had been involved in early stages of trial design. Another case of #NothingAboutUsWithoutUs
@stage4kelly @PTarantinoMD I mean, all speculation...but yes, if crossover had been allowed and patients did BETTER if they got cami EARLIER, 💯 we'd have an approval right now in my opinion. When this trial enrolled, patients didn't have access to subsequently get a SERD.
@ErikaHamilton9 FDA suggests a new clinical trial: Arm A — Early Intervention Strategy Imediate switch to: camizestrant + CDK4/6 inhibitor Arm B — Standard Strategy Continue: aromatase inhibitor (AI) + CDK4/6 inhibitor Switch to: camizestrant + CDK4/6 inhibitor upon Radiologic progression
As patients, most of us want the same thing: promising science, thoughtful drug development, & clear evidence that new approaches will meaningfully help patients live better & longer. Today's FDA ODAC discussion on #SERENA6 & #camizestrant was an important reminder that encouraging data is only part of the story. What matters most is whether a treatment change will truly improve outcomes in ways that are meaningful for patients. That patient-centered focus matters. I found the @US_FDA position statements in the briefing doc very helpful (highlighted in 🌑): 📌Also - involve pt advocates in clinical trial design, from the start! 😉 #PatientCenteredMedicine #Oncology #bcsm #ODAC #Advocacy #metastaticbreastcancer
Her quote tweet was amplified by the Oncology Brothers and Dr. Carmine Valenza, author of the Lancet Oncology comment on the SERENA-6 publication.
Want to go to the source? Dr. Tatiana Prowell shared the full ODAC meeting video and transcript (AM session): "Good #MedEd for #OncTwitter."
Her discussion also covered serial-testing logistics: 3,256 patients screened serially, 548 (17%) with ESR1 mutations, 315 (57%) agreeing to be randomized, 52 (9%) with concurrent anatomic progression at detection. She asked whether "test-xiety" joins "scan-xiety" in the surveillance experience. Plenary-day reactions:
Tremendous discussion of the SERENA-6 trial by @AngieDemichele. Outstanding results, though not ready for clinical practice (yet). Important to take into account financial, psychological & systemic costs of the strategy. Make sure to review this presentation if you missed it.
I am loving Dr. DeMichele’s comments, including her insistence on longer survival and discussion of crossover issues. #ASCO25 #plenary #serena-6 Also loving audience questions. They are asking hard questions on the utility of PFS. I feel happy that the education is spreading and audience are asking the questions that people didn’t use to ask a few years ago. The status quo does seem to be changing. That makes me happy. Also, for a full discussion of all issues that are being discussed, read CSO checklist paper
This discussion of SERENA-6 trial was excellent. #ASCO25 This doesn’t feel practice changing to me.
Dr. DeMichele highlights the importance of clinical utility. - PFS2 did not reach the high bar for statistical significance. But should it have been defined with different parameters? - No crossover is a limitation, and serial ctDNA is burdensome and costly. #ASCO25
TLDR: I agree w/ ODAC. My personal opinion as a clinician: current SERENA-6 results do not persuade me that changing treatment for ESR1m emergence w/o radiographic progression benefits patients. 😕Much higher cost + safety issues & no survival benefit at this point. #bcsm
SERENA-6 is innovative, but caution is needed. Switching therapy based on ctDNA before radiologic progression may improve PFS without changing OS. Are we truly changing the disease course, or simply changing when we start the next treatment?
Fantastic news to end the week! 🎉 FDA accelerated approval: camizestrant + CDK4/6i at ESR1 emergence on 1L AI + CDK4/6i (SERENA-6). mPFS 16.0 vs 9.2 mo, HR 0.44. First approval ever driven by ctDNA, not imaging. Molecular progression is now actionable in the US. So happy for our patients who want to stay a step ahead of their cancer.
#camizestrant approval for 1.5L ER+ #bcsm w/ the emergence of ESR1m in the absence of progression 1st line. Camizestrant is a drug we have loved using across all settings but this particular study is a paradigm shifting study w/ its molecular trigger!
@FDA granted accelerated approval for camizestrant today based on SERENA-6: switching therapy when an ESR1 mutation appears in ctDNA, before scans show progression. This is resistance defined, drugged, and tracked at the bedside. I served as Chair of the Oncologic Drugs Advisory Committee (ODAC) on this trial. My recent @JAMAOnc piece discussed the vote and regulatory issues around detecting cancer before it is seen: jamanetwork.com/journals/jamaoncology/fullarticle/2852935
FDA grants accelerated approval to Etcamah (camizestrant) + CDK4/6i (abemaciclib, palbociclib, ribociclib) for HR+/HER2- advanced BC upon ESR1 mutation detected during AI + CDK4/6i therapy, by FDA-authorized test. Pro: mPFS 16 vs 9.2 mo per label. In SERENA-6, final PFS2 25.7 vs 19.1 mo (HR 0.63) and 46% lower risk of deterioration in global health status/QOL. Con: Accelerated approval, OS immature, confirmatory trials required. Boxed warning for irregular heart rhythm with certain concomitant meds, plus bradycardia. First trial to intervene on molecular resistance in breast cancer before clinical PD. #bcsm
Camizestrant approved in patients with emerging mESR1 by ctDNA in the absence of PD. @OncoAlert @OncBrothers
➡️As a biomarker advocate, this decision needs commenting. #SERENA6 proves #camizestrant has strong drug activity in emerging ESR1m disease, stronger than approved SERDs post-progression. FDA accepts PFS without OS for other SERDs at radiographic progression; the higher bar here is apparently the earlier PFS start point. But the 9.2m control PFS does not mean "no need to act" it is a window where ESR1 subclones can be intercepted before broader and tougher to treat resistance biology beyond ESR1m emerges and dominates. Two separate questions: drug efficacy evidence (clearly established) vs strategy evidence (needs further study). Demanding a definitive strategy trial before approving a drug with this activity sets a precedent that, IMO, will harm precision oncology. Such a trial needs years more time, money, patients & impossible in a changing 2L landscape. @oncoalert @FDAOncology #bcsm
More reactions, verbatim and sourced, including Drs. Sahin, Kurian and Choueiri and the institutional statements: the SERENA-6 trial profile. Patient-reported outcomes are published in Mayer et al., Annals of Oncology.
On approval day, Dr. Tarantino highlighted "our podcast episode dissecting the SERENA6 strategy with the one and only @hoperugo": Episode 5 of the Breast Friends Podcast, "Dr. Hope Rugo: The Evolution of Breast Oncology" (May 2026), hosted by Drs. Tarantino and Mouabbi:
It took a while, but camizestrant has finally been approved based on SERENA-6. This is also an important milestone in recognizing molecular progression as a clinically actionable event. The next question is even more relevant: Is there a survival benefit to switching to an oral SERD at molecular progression, rather than continuing current therapy and switching to an oral SERD only after radiologic progression?
Altho we all want cami approval it is important to note the novel & futuristic trial design. Changing Rx for resistance markers vs PD. Lack of crossover an issue in determining LT benefit. Low return of QOL docs. We need to be smarter in trial design. And it’s not over for S6!
The SERENA-6 PFS2 results were presented at #ASCO26 . The full-text is now published, but the OS data remain immature. The current curves do not show a clear separation. Whether an OS benefit will emerge with longer F/U remains an open question.
There will be people who agree & disagree with @US_FDA decision on #SERENA6 #cami, but fantastic document by FDA 👏 educating & clearly outlining reasons for the decision and how PFS2 will be interpreted. A must read for drug developers and pharma.
The record, in order: the plenary discussant called clinical utility unproven in June 2025. ODAC voted 6–3 no in April 2026. The FDA approved on September 4, on PFS, with its Oncology Center of Excellence Director attaching the caveat that "additional evidence is needed to confirm clinical benefit." Credible KOLs still hold the ODAC position after approval day. Which voices move, and what data moves them, is what the SERENA-6 trial profile tracks.
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KOL Pulse tracks what verified oncology and hematology physicians are actually discussing on X — not press releases, the real clinical debate. Every KOL tweet quoted here is verbatim and links to its source post; congress remarks are quoted from the presented slides. Featured voices: Drs. Tatiana Prowell, Angela DeMichele (via her ASCO discussion slides), Paolo Tarantino, Bishal Gyawali, Ryan Huey, Rishabh Jain, Ali Aytaç, Jose Fernando Moura, Yakup Ergün, Sherene Loi, Erika Hamilton, Hope Rugo, Sarah Sammons, Jason Mouabbi, and Neil Vasan.
Clinical figures verified against the FDA approval announcement, the ODAC meeting transcript, and the sourced record on the KOL Pulse SERENA-6 trial profile. Editorial/educational content; not medical advice. © 2026 KOL Pulse.