Brian Shields
Today at #ESMO26, the 6-year results of NATALEE will be presented. Ahead of the presentation, my personal view on the survival gains with adjuvant CDK4/6 inhibitors…
The 6-year OS rates in NATALEE were 91.86% vs 89.73%: an absolute gain of 2.1 percentage points (HR 0.809; 95% CI 0.661–0.989; nominal one-sided p=0.019).
The absolute 7-year OS gain in monarchE was 1.8 percentage points (HR 0.842; p=0.027). I do not think these gains should be dismissed as “only 2%.”
In the EBCTCG analysis, adding taxanes to anthracycline-based chemotherapy—an approach we have accepted as standard for years—provided an absolute 5-year OS gain of approximately 1.9 percentage points. The populations and follow-up periods differ, so we cannot directly compare treatment efficacy. However, the standards we use to judge a few percentage points of survival benefit should be consistent.
Moreover, 95.4% of patients in monarchE had already received chemotherapy. This survival gain represents an additional benefit on top of chemotherapy and endocrine therapy.
Patient selection, toxicity, treatment duration, and cost certainly deserve discussion. However, the survival benefit of adjuvant CDK4/6 inhibitors in appropriately selected patients should not be underestimated.
View post on X ↗
KOL Pulse · ESMO 2026 · Madrid · Breast cancer · October 23–25
ESMO 2026: Top Breast Cancer Trials and KOL Voices
NATALEE drew the most physician posts on breast cancer at ESMO 2026. At 6 years, adjuvant ribociclib showed an OS difference of 2.1 points (HR 0.809, nominal P=.019). Medical oncologist Yakup Ergün wrote: “I do not think these gains should be dismissed as “only 2%.”” Oncologist Timothée Olivier asked: “Does this survival difference truly inform clinical practice in settings where CDK4/6i are standard of care for metastatic disease?” … “In my opinion, the answer is no.” KEYNOTE-B49 was second: pembrolizumab improved PFS but not overall survival. Below are the eight most-discussed breast cancer trials from October 23–25, each with the result, a presented slide and physician posts quoted in full, then the top breast cancer physicians on X and the sessions still ahead.
Most-discussed breast cancer trials
Physician posts on X, October 23–25.
| # | Trial | Physician posts | Physicians posting |
|---|---|---|---|
| 1 | NATALEE | 46 | 30 |
| 2 | KEYNOTE-B49 | 30 | 22 |
| 3 | PANKU-Breast01 | 25 | 21 |
| 4 | FOURLIGHT-1 | 22 | 19 |
| 5 | TALENT | 22 | 17 |
| 6 | TROPION-Breast02 | 20 | 18 |
| 7 | postMONARCH | 15 | 14 |
| 8 | APEX-Breast01 | 15 | 13 |
Next on the list: HORIZON-Breast06 (14 posts; trial page), NSABP B-42 (14) and evERA (13; trial page).
The trials
1. NATALEE: 6-year overall survival with adjuvant ribociclib
Ribociclib + NSAI vs NSAI alone in stage II–III HR+/HER2− early breast cancer. 6-year OS 91.86% vs 89.73% (difference 2.1%); HR 0.809 (95% CI 0.661–0.989); nominal one-sided P=.019. Breast cancer–specific survival HR 0.706 (0.559–0.890). 6-year iDFS 83.23% vs 77.92%, HR 0.741 (0.646–0.849). (ESMO 2026 LBA25 abstract, Dennis Slamon; data cutoff May 15, 2026; median OS follow-up 66.5 months) Adjuvant ribociclib has been FDA approved since September 17, 2024. (KOL Pulse NATALEE page)
The debate was whether a 2.1-point OS difference with a nominal P value should change practice, and how much limited CDK4/6 inhibitor use after relapse in the control arm matters.
“Only 2%”?
Mali Barbi, MD MSc | Breast & Gyn Oncologist @DrBarbiOnc
breast and gynecologic oncologist, Northwell Health · Oct 23
#NATALEE OS is here. HR 0.81, 178 vs 205 deaths, 6-year OS difference 2.1%. monarchE was HR 0.84, 1.8% at 7 years. Two CDK4/6 inhibitors, two schedules, strikingly similar survival effect.
The OS gap widens after ribociclib stops at year 3, as expected since deaths lag relapses. More importantly, the iDFS curve is still separating after treatment ended. And control patients who relapsed could get a CDK4/6i for metastatic disease, which should shrink the OS difference. The benefit held.
What NATALEE adds over monarchE is N0, about 12% of the trial. The iDFS signal is there. N0 OS will be underpowered for a long time, so that conversation in clinic stays an iDFS conversation. #bcsm #ESMO26
View post on X ↗NATALEE 6-y results are out! #ESMO26
2.1 delta in survival at 6 years.
Thanks @Annals_Oncology for reporting subsequent therapy data!
👉Only 44.4% of control arm patients with distant recurrence received a first-line CDK4/6i
Does this survival difference truly inform clinical practice in settings where CDK4/6i are standard of care for metastatic disease?
In my opinion, the answer is no.
View post on X ↗2. KEYNOTE-B49: pembrolizumab + chemotherapy in PD-L1–positive HR+/HER2− metastatic disease
Phase 3, N=342 (Merck): pembrolizumab or placebo added to chemotherapy in HR+/HER2− locally recurrent inoperable or metastatic breast cancer with PD-L1 CPS ≥1, after endocrine therapy. Hope S. Rugo presented the final analysis (LBA51), published the same day in Annals of Oncology. PFS by BICR, the primary endpoint, was 6.7 vs 6.0 months, HR 0.74 (95% CI 0.58–0.95), P=0.0089; 24-month PFS 15.0% vs 4.3%. In the CPS ≥10 subgroup (72 patients, a secondary endpoint), PFS HR was 0.59 (0.35–0.98). (ESMO 2026 LBA51 abstract and slides; interim analysis, data cutoff Sep 22, 2025) Overall survival, the key secondary endpoint, was 21.0 vs 22.2 months, HR 1.04 (0.81–1.33), P=0.6185, not met. Grade ≥3 treatment-related AEs 37.6% vs 32.7%; 3 treatment-related deaths (1.8%) with pembrolizumab vs none. (LBA51 slides; final analysis, data cutoff Mar 16, 2026) Pembrolizumab in HR+/HER2− breast cancer is investigational; its FDA-approved breast cancer indications are in triple-negative breast cancer. (KOL Pulse KEYNOTE-B49 page)
Physicians agreed the median PFS gain was small. The counterpoint was the tail of the PFS curve and the CPS ≥10 subgroup. A co-author of the study, Giampaolo Bianchini, called for better biomarkers. On October 25, Sherene Loi, a co-chair of Monday’s advanced breast cancer rapid oral session, pointed to early high-grade HR+ disease instead.
Modest median, longer tail
Giampaolo Bianchini @BianchiniGP
head of the breast cancer group, San Raffaele, Milan; KEYNOTE-B49 co-author · Oct 24
🔥 KEYNOTE-B49 meets its primary endpoint, but benefit seems limited to few patients
👉 ICIs benefit selected ER+/HER2− BC pts (CPS≥10, ER-low)
👉 Are ADCs better ICI partners than CT?
👉 What about PD-1/VEGF bispecifics?
➡️ Better biomarkers urgently needed!
#ESMO26 https://t.co/xtA0X9K0CZ
View post on X ↗Stephanie Graff, MD, FACP, FASCO @DrSGraff
director of breast oncology, Brown University Health · Oct 24
KN-B49 @hoperugo PDL1+ HR+ MBC after ET tx w/chemo +/-Pembro
Chemo: cape, doxil, taxanes
Pembro improved mPFS 6 to 6.7 mos; no OS gain
Complicated for practice w/ modest gain, ADCs in a competing space, and the pt burden of adding Pembro to oral cape. #ESMO26 @OncoAlert https://t.co/durudyjrCs
View post on X ↗
Erika Hamilton, MD, FASCO @ErikaHamilton9
breast oncologist, Sarah Cannon Research Institute · Oct 24
KNB49 HR+ adv #bcsm with PDL+, chemo +/- pembro once chemo appropriate
Only 19.4% of pts eligible (majority weren't PDL1+)
~79% of + were CPS 1-9
PFS improved 6 to 6.7 mo, but tail of curve much better at 24 mo 4.3 vs. 14% remaining on
PFS CPS of 19 4.4 vs. 7.5 mos
#ESMO26 https://t.co/pwtswREUTg
View post on X ↗STATISTICALLY POSITIVE. CLINICALLY THIN.
KEYNOTE-B49: pembrolizumab + chemo delivered just +0.7 months median PFS in PD-L1 CPS≥1 HR+/HER2− advanced breast cancer with no OS benefit.
Significance ≠ meaningful benefit.
@hoperugo #ESMO26 https://t.co/KrBy46HOX1
View post on X ↗
#keynoteB49- @myESMO #ESMO26
Adding ICB/ immunotherapy in advanced HR+ #breastcancer - wishful thinking 🤔 this context is immune deplete! -PFS 6-6.7 mo
➡️ Early high grade immune + HR + BC is the right place for it
#ESMOAmbassadors https://t.co/nTuY30fwfU
View post on X ↗3. PANKU-Breast01: iza-bren vs chemotherapy in pretreated HR+/HER2− disease
Phase 3, N=383, conducted in China: iza-bren (izalontamab brengitecan, an EGFR×HER3 bispecific ADC) vs physician’s-choice chemotherapy. PFS by BICR 8.18 vs 4.01 months, HR 0.41 (95% CI 0.33–0.53), P<0.0001. ORR 40.5% vs 20.2%. OS immature. ILD in 2 patients (1.1%), grade 1–2. (ESMO 2026 LBA50 abstract, Bo Lan; data cutoff Jul 21, 2026) Grade ≥3 TRAEs 85.3% vs 65.8%; dose reductions 64.7% vs 28.5%; grade ≥3 neutropenia 53.7%, anemia 49.5%, thrombocytopenia 46.3% with iza-bren. (LBA50 slides) Iza-bren is investigational and not FDA approved in any indication.
Physicians noted the PFS and response gains. The questions were hematologic toxicity and sequencing after other ADCs.
Efficacy vs hematologic toxicity
Erika Hamilton, MD, FASCO @ErikaHamilton9
breast oncologist, Sarah Cannon Research Institute · Oct 23
#PANKUBreast01
Ph III results for iza bren (bispecific EGFR/HER3 ADC) vs TPC chemo, in previously treated HR +/HER- MBC
🔹mPFS: 4.0 vs. 8.1 mo, HR 0.41
🔹 ORR: 20% vs 40%
🔹 DoR: 4.2 vs. 6.9 mo
🔹 ILD: only 1.1% & all grade 1/2
#ESMO26 #ESMOAmbassadors https://t.co/ikHLXiLHX1
View post on X ↗
🇨🇳 PANKU-Breast01: the HER3-EGFR bispecific TOPO1 ADC Iza-Bren improved PFS vs chemo in HR+/HER2- MBC (OS immature). High rate of hematologic toxicity, with ~50% G3+ anemia, neutropenia and thrombocytopenia, and most patients requiring dose reductions⚠️. #ESMO26 #ESMOAmbassadors https://t.co/f1zn2X0bpe
View post on X ↗#ESMO2026
Panku-breast01
Izabren sig. improves PFS in met HR+HER2 post CDK4i
#BreastCancer
👏New targets 🎈impressive ORR too
➡️broadly comparable to DB04 - here all HER2
But 🎈haem tox
Still have the what next issue 🤷🏻♀️
Online publication in @TheLancetOncol
#ESMOAmbassadors #bcsm @OncoAlert @myESMO
View post on X ↗4. FOURLIGHT-1: atirmociclib, a CDK4-selective inhibitor, after a CDK4/6 inhibitor
Randomized Phase 2 (Pfizer): atirmociclib + fulvestrant vs investigator’s choice of endocrine-based therapy in HR+/HER2− advanced breast cancer after a CDK4/6 inhibitor. Antonio Giordano presented. Investigator-assessed PFS favored atirmociclib. Atirmociclib is investigational. Physicians pointed to the first-line Phase 3 trial, FOURLIGHT-3, as the next readout.
A co-author called the data strong. Others noted this is a Phase 2 result and that the control arm matters.
Phase 2 signal, Phase 3 next
@antgiorda beautifully presents our data from Fourlight 1 with the CDK4i atirmociclib/fulv vs fulv or eve/exe as 2nd line Rx for HR+ MBC. At 13.7 mo med FU, n=263, 38%esr1m, 40% PIKm, PFS 9.4 v 6.6mo HR 0.6 p0.007. Beautiful data. Await Fourlight 3 1st line study! @OncoAlert
View post on X ↗🔥 FOURLIGHT-1 demonstrates atirmociclib efficacy post-CDK4/6i
⚠️ Phase II trial: not practice-changing yet
👉 These results reinforce expectations that atirmociclib may outperform other CDK4/6i
➡️ FOURLIGHT-3 results eagerly awaited
Congrats to my friend @antgiorda
#ESMO26 https://t.co/IBGIoA05Rc
View post on X ↗Mali Barbi, MD MSc | Breast & Gyn Oncologist @DrBarbiOnc
breast and gynecologic oncologist, Northwell Health · Oct 24
After CDK4/6i in HR+ MBC, the control arm is the story at #ESMO2026.
FINER: fulvestrant alone, median PFS 1.9 mo. Ipatasertib + fulvestrant 5.4 mo, HR 0.68. In AKT pathway-altered tumors, HR 0.55.
FOURLIGHT-1: atirmociclib, a CDK4-selective inhibitor, 9.4 vs 6.6 mo with investigator's choice, HR 0.60. 85 to 92% randomized within 3 months of their last CDK4/6i.
Fulvestrant alone after a CDK4/6i is close to no treatment. FINER helped even without selection, but with toxicity FOURLIGHT-1 tests whether keeping CDK4 pressure on, more selectively, beats switching. #bcsm #ESMO26
@myESMO
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5. TALENT: neoadjuvant T-DXd in HR+/HER2-low early breast cancer
Phase 2, 132 patients, three arms: T-DXd alone, T-DXd + anastrozole, or T-DXd followed by docetaxel-cyclophosphamide. pCR (RCB0) 7% (3/45), 3% (1/29) and 9% (5/58). RCB0/1 16%, 17% and 17%. Grade ≥3 treatment-related AEs 24%, 17% and 28%; 3 cases of grade 2 ILD; 1 treatment-related death in the T-DXd-alone arm. (ESMO 2026 LBA23 slides, Sara A. Hurvitz) Neoadjuvant T-DXd is investigational. Enhertu is FDA approved in HER2-low breast cancer only for unresectable or metastatic disease. (KOL Pulse TALENT page)
Physicians called the pCR rates low. One noted that pCR is a limited surrogate endpoint in HR+ disease.
High response, low pCR
TALENT trial presented by Sara Hurvitz: Preop TDXd in HR+ HER2-low breast cancer
Preop TDXd: 7%
TDXd+AI: 3%
TDXd-->TC: 9%
Adding endocrine therapy and sequencing chemo with TDXd didn't seem to improve pCR
@OncoAlert #ESMO2026 https://t.co/dArlOO4Mpa
View post on X ↗Erika Hamilton, MD, FASCO @ErikaHamilton9
breast oncologist, Sarah Cannon Research Institute · Oct 23
TALENT- neoadj T-DXd in HR+/HER2-low #bcsm
RCB0/1:
🔹 T-DXd alone: 16%
🔹 T-DXd + anastrozole: 17%
🔹 T-DXd → TC chemo: 17%
*no pCRs w/out 8 cycles
Despite high ORR ~66%, pCR LOW! We know w/ HR+ we don't get high pCRs rates, but still disappointing
#ESMO26 #ESMOAmbassadors https://t.co/smlF5DmAAt
View post on X ↗#ESMO26 | TALENT
Neoadjuvant T-DXd showed very low pCR rates in HR+/HER2-low early breast cancer:
- T-DXd: 7%
- T-DXd + anastrozole: 3%
- T-DXd → chemotherapy: 9%
We should remember that pCR is a limited surrogate endpoint in HR+ disease. However, these results do not support T-DXd as an alternative to standard neoadjuvant chemotherapy.
Moreover, given the heterogeneity of HER2-low disease, I find it unsurprising that the success of T-DXd in the metastatic setting does not translate into similar outcomes in early-stage disease, despite the lower tumor burden.
View post on X ↗6. TROPION-Breast02: Dato-DXd in patients with brain metastases
Phase 3 (Daiichi Sankyo and AstraZeneca): datopotamab deruxtecan vs chemotherapy as first-line treatment for metastatic TNBC in patients who are not candidates for PD-1/PD-L1 therapy. Primary analysis: PFS by BICR 10.8 vs 5.6 months, HR 0.57 (95% CI 0.47–0.69), P<0.0001; OS 23.7 vs 18.7 months, HR 0.79 (0.64–0.98). (ESMO 2025 LBA21; data cutoff Aug 25, 2025; same medians and HRs in the May 22, 2026 FDA approval) Datroway has been FDA approved for this population since May 22, 2026. (KOL Pulse TROPION-Breast02 page) At ESMO 2026, Rebecca Dent presented an exploratory analysis of the patients with brain metastases at baseline (LBA96). In the patients with brain metastases at baseline (35 vs 26), median CNS PFS was 9.5 vs 2.6 months, HR 0.27 (95% CI 0.13–0.56). This analysis is exploratory. (LBA96 slide, Rebecca Dent, as tabulated on the KOL Pulse TROPION-Breast02 page; no data cutoff shown on the slide)
Physicians agreed the intracranial activity is real. They differed on whether it is ready for clinic, given the small, exploratory subgroup.
Ready for clinic?
@RebeccaDSing presents efficacy of Dato-Dxd in patients with TNBC on TB02. In the small subset with BMs Dato DXd improved CNS response and PFS! Nice data immediately applicable to clinical practice. @myesmo #ESMO2026 @OncoAlert https://t.co/AeMylHCL7g
View post on X ↗TROPION-Breast02 brain mets analysis at #ESMO26 (Dent). 1L Dato-DXd vs chemo, mTNBC, n=61 with BMs:
CNS PFS 9.5 vs 2.6 mo, HR 0.27
icORR (measurable) 62.5% vs 37.5%
Untreated BMs: OS HR 0.35
Longest icDoR ~27 mo
Preferred Trop2 ADC for brain Mets! @RebeccaDSing
Exploratory, small n, real CNS signal. #bcsm
View post on X ↗Mali Barbi, MD MSc | Breast & Gyn Oncologist @DrBarbiOnc
breast and gynecologic oncologist, Northwell Health · Oct 24
TROPION-Breast02, brain mets subgroup at ESMO 2026. First-line Dato-DXd vs chemo in mTNBC, n=61.
CNS PFS 9.5 vs 2.6 mo, HR 0.27. Intracranial ORR 62.5% vs 37.5%. Longest intracranial response about 27 mo.
In TNBC, brain mets come early and we usually treat them locally first. This makes me ask whether a patient with small asymptomatic lesions could start Dato-DXd and defer /combine SRS
Not ready for clinic. This is a post hoc subgroup, n=30 with untreated brain mets. And even on Dato-DXd, median OS was 11.6 mo with brain mets vs 23.7 mo without. The CNS benefit is real; the prognosis is still poor. The answer needs a dedicated CNS trial. #bcsm #ESMO26
@myESMO
View post on X ↗7. postMONARCH: final overall survival with abemaciclib after a CDK4/6 inhibitor
Phase 3, N=368 (Eli Lilly): abemaciclib + fulvestrant vs placebo + fulvestrant after progression on a CDK4/6 inhibitor plus endocrine therapy. Final OS (secondary endpoint): median 32.1 vs 24.6 months, HR 0.80 (95% CI 0.60–1.06), log-rank P=0.11, not statistically significant. Updated investigator-assessed PFS (primary endpoint): 5.9 vs 5.3 months, HR 0.78 (0.62–0.99), P=0.039. Exploratory PFS2 HR 0.76 (0.59–0.97) and time to chemotherapy HR 0.76 (0.58–0.99). (ESMO 2026 1RO slides, Kevin Kalinsky; data cutoff Mar 6, 2026; median follow-up 37 months) Abemaciclib after a CDK4/6 inhibitor is investigational; abemaciclib is FDA approved in other HR+/HER2− breast cancer settings. (KOL Pulse postMONARCH page)
Physicians read the OS result differently: a continued benefit for some, not a preferred second-line option for others, given biomarker-directed therapies.
Numerical OS gain, not significant
#ESMO2026
PostMonarch - change to Fulvestrant v placebo with Abema- continues to show better PFS and OS
➡️ results by ESR1 status eagerly awaited!
#ESMOAmbassadors @OncoAlert
Published online in @Annals_Oncology https://t.co/Bzolx5kqxi
View post on X ↗#ESMO26 | postMONARCH – Final OS
After progression on CDK4/6i + ET, median OS with abemaciclib + fulvestrant was 32.1 vs 24.6 months, but statistical significance was not reached (HR 0.80; 95% CI 0.60–1.06; p=0.11).
The 7.5-month difference in median OS is noteworthy, but these results do not make this combination a preferred second-line option for me, given the availability of biomarker-directed therapies.
View post on X ↗🔥 Abema + fulvestrant after 1L CDK4/6i/AI improves PFS, PFS2 & time to chemo; numerical ↑OS
👉 CDK targeting remains valid post-CDK4/6i, but NOT a class effect!
✅ Abema (postMONARCH, EMBER-3), atirmociclib (FourLight-1), ribo (MAINTAIN)
⛔ Palbo (PACE, PALMIRA)
#ESMO26 https://t.co/KxHmObP6Oc
View post on X ↗8. APEX-Breast01: TQB2102, a biparatopic HER2 ADC, in HER2-low disease
Phase 3 (Chia Tai Tianqing): TQB2102 (rolditamig deuderuxtecan) vs physician’s-choice chemotherapy in HER2-low recurrent or metastatic breast cancer. Shusen Wang presented. PFS by blinded independent review, the primary endpoint in the HR+/HER2-low population, favored TQB2102. TQB2102 is investigational.
With HORIZON-Breast06 in the same session, physicians asked what a third HER2 ADC with a topoisomerase I payload adds when the comparator was chemotherapy, not T-DXd.
Another HER2 ADC vs chemotherapy
🇨🇳 TQB2102 (biparatopic HER2 TOPO1 ADC) also passes the truck test in mostly HR+/HER2-low MBC. PFS 16.4 vs 5.5 mo, HR 0.29, p<0.01. Unclear whether the biparatopic design adds anything. The HER2 TOPO1 field is getting quite crowded with excellent agents. #ESMOAmbassadors #ESMO26 https://t.co/nOV5QhN7PR
View post on X ↗Three HER2 ADCs now in HER2-low MBC. At #ESMO26, HORIZON-Breast06 & APEX-Breast01 both beat chemo on PFS (HR ~0.25–0.29). But as @BarbaraPistill2 noted: same payload class as Tdxd, tested vs chemo not the standard. Head-to-head ADC trials needed. #ESMOAmbassadors @myESMO https://t.co/Yntya2iiR3
View post on X ↗First breast session at #ESMO26 highlights how China is developing novel drugs at rapid speed.
Positive PFS results with HER2-directed ADCs (HORIZON-Breast06 + APEX-Breast01), but neither compare to current SoC of T-DXd.
Fights for market share, but does it push the needle?
View post on X ↗KOL Voices: the top breast cancer physicians at ESMO 2026
The top 10 physicians in the breast cancer tab of the ESMO 2026 KOL leaderboard, with one line from each and the trial it is about.
- Yakup Ergün @dr_yakupergun · medical oncologist
on KEYNOTE-B49 → “Evaluating immunotherapy in combination with ADCs or after ADC treatment may be more rational in today's treatment landscape.” - Paolo Tarantino @PTarantinoMD · medical oncologist, Dana-Farber
on NATALEE → “Efficacy comparable to abema (monarchE), with different toxicity profile and wider population (N+ and high-risk N0).” - Erika Hamilton, MD, FASCO @ErikaHamilton9 · breast oncologist, Sarah Cannon Research Institute
on FOURLIGHT-1 → “**1st line trial and curative trials coming!***” - Aya Mohamed | MSc, MD 🎗 @Dr_Oncologista · medical oncologist, breast cancer
on postMONARCH → “Abemaciclib After CDK4/6 Inhibitor Progression — PFS Benefit Without a Statistically Significant OS Improvement” - Sara Tolaney @stolaney1 · chief of breast oncology, Dana-Farber
on NATALEE → “6 yr OS HR 0.809 (delta 2.1%)” - Rebecca Shatsky, MD @Dr_RShatsky · breast medical oncologist, UC San Diego
on FINER → “If we allow 40% de novo metastatic disease on a trial we can’t really say it’s representative of the general MBC population.” - Stephanie Graff, MD, FACP, FASCO @DrSGraff · director of breast oncology, Brown University Health
on TALENT → “ypCR just isn’t the same endpoint w/ ER+ disease” - Matteo Lambertini, MD PhD @matteolambe · medical oncologist, University of Genova
on KEYNOTE-B49 → “more translational research is needed to improve our understanding on how to optimize #immunotherapy use in luminal-like disease” - Kristina Jankovic, MD @JankovicK · medical oncology resident, Niš
on APEX-Breast01 → “Impressive #APEXBreast01 data showing benefit with rolditamig deuderuxtecan over first-line chemotherapy in HR+/HER2-low metastatic #BreastCancer!” - Philippe Aftimos, MD @aftimosp · medical oncologist, Institut Jules Bordet
on FOURLIGHT-1 → “Next step: the FourLight-3 ph3 study in the 1L vs CDK4/6i”
What’s yet to come: breast cancer sessions on October 26–27
Times are Madrid time. Results are not out yet; physician reactions will appear on the ESMO 2026 trials page as they post.
Mon Oct 26 · 08:30-09:15 (Madrid) · Granada Auditorium - Hall 4
Challenge your expert: Management of early breast cancer in young patients
- 08:30-08:50 Presentation by Expert — Matteo Lambertini
- 08:50-09:15 Discussion led by Chair — Shani Paluch-Shimon
Mon Oct 26 · 10:15-11:45 (Madrid) · Alicante Auditorium - Hall 6
Rapid oral 2: Breast cancer, advanced stage
Chairs: Antonio Llombart Cussac, Pedram Razavi, Sherene Loi.
- 10:15-10:20 4639RO - Final OS analysis of sacituzumab tirumotecan versus chemotherapy in previously treated locally recurrent or metastatic triple-negative breast cancer: Phase III OptiTROP-Breast01 — Man Li
- 10:20-10:25 4RO - Target switching with conserved-payload novel ADCs in patients with metastatic breast cancer following prior ADC therapy (SWITCH): A prospective, open-label, phase 2 platform trial — Lei Fan
- 10:25-10:30 5RO - Safety and efficacy of SYS6043, a novel B7-H3—targeting antibody-drug conjugate, in patients with advanced breast cancer — Hongxia Wang
- 10:30-10:35 4640RO - Bulumtatug fuvedotin (BFv, 9MW2821), a nectin-4–directed antibody-drug conjugate (ADC), in patients with locally advanced or metastatic triple negative breast cancer (la/mTNBC) previously treated with topoisomerase I inhibitor (TopI)-based ADCs: Results from a phase 2 study — Yanchun Meng
- 10:35-10:50 Invited Discussant 4639RO, 4RO, 5RO and 4640RO — Sherene Loi
- 10:50-10:55 1767RO - BRIDGET: A phase II trial of tucatinib added to trastuzumab/pertuzumab or ado-trastuzumab emtansine after isolated intracranial progression in patients with advanced HER2-positive breast cancer — Sarah Sammons
- 10:55-11:00 1768RO - Radiation therapy followed by intrathecal (IT) trastuzumab/pertuzumab in the management of HER2+ breast leptomeningeal metastasis: Results from a phase II multi-institutional study, (INSPIRE-LM) — Kamran Ahmed
- 11:00-11:05 LBA49 - A DESTINY-Breast09 (DB-)09 analysis of trastuzumab deruxtecan (T-DXd) + pertuzumab (P) vs taxane + trastuzumab + pertuzumab (THP) for patients (pts) with HER2+ advanced/metastatic breast cancer (a/mBC) and baseline (BL) brain metastases (BMs) — Cristina Saura Manich
- 11:05-11:17 Invited Discussant 1767RO, 1768RO and LBA49 — Antonio Llombart Cussac
- 11:17-11:22 1769RO - CTC characterization with the DETECT CTC score predicts therapy response in triple-positive aBC: Translational results of the phase III DETECT V study — Kerstin Pfister
- 11:22-11:27 1770RO - Ultra-sensitive MRD assessment in long-term complete responders to anti-HER2 therapy in HER2-positive metastatic breast cancer: Initial results from HER2-CR study — Kazuki Nozawa
- 11:27-11:47 4449RO - Paired-biopsy multi-omic analysis reveals target-independent mechanisms of antibody–drug conjugate (ADC) resistance in metastatic breast cancer (MBC) — Paolo Tarantino
- 11:47-11:57 Invited Discussant 1769RO, 1770RO and 4449RO — Pedram Razavi
Mon Oct 26 · 14:45-16:15 (Madrid) · Almeria Auditorium - Hall 9
Special symposium: Incorporation of biomarkers for early breast cancer
- 14:45-15:05 Dynamic tissue-based biomarkers to guide treatment — Carsten Denkert
- 15:05-15:25 Current use of genomic assays — Kevin Kalinsky
- 15:25-15:45 How to integrate new imaging techniques in the clinic — Ritse Mann
- 15:45-16:05 MRD to inform treatment decision — Nicholas Turner
Tue Oct 27 · 11:40-12:20 (Madrid) · Barcelona Auditorium - Hall 9
Scientific Congress Highlights 2: Breast cancer, early and advanced stage
- 11:40-12:20 Breast cancer, early and advanced stage — Giuseppe Curigliano
FAQ
Which breast cancer trials did physicians discuss most at ESMO 2026?
By physician posts on X on October 23-25, the most-discussed breast cancer trials were NATALEE, KEYNOTE-B49, PANKU-Breast01, FOURLIGHT-1, TALENT, TROPION-Breast02, postMONARCH and APEX-Breast01.
Did NATALEE show an overall survival benefit at 6 years?
6-year OS was 91.86% vs 89.73% (HR 0.809, 95% CI 0.661-0.989) with a nominal one-sided P=.019 (ESMO 2026 LBA25 abstract, data cutoff May 15, 2026). Physicians disagreed on how much weight to give it. Adjuvant ribociclib has been FDA approved since September 17, 2024.
Did KEYNOTE-B49 improve survival with pembrolizumab in HR+/HER2- breast cancer?
PFS improved: 6.7 vs 6.0 months, HR 0.74 (95% CI 0.58-0.95), P=0.0089 (interim analysis, data cutoff September 22, 2025). Overall survival did not: 21.0 vs 22.2 months, HR 1.04 (0.81-1.33) (final analysis, data cutoff March 16, 2026). Pembrolizumab in HR+/HER2- breast cancer is investigational (ESMO 2026 LBA51, KOL Pulse KEYNOTE-B49 page).
Did postMONARCH improve overall survival?
Median OS was 32.1 vs 24.6 months (HR 0.80, 95% CI 0.60-1.06, log-rank P=0.11). The difference was not statistically significant (ESMO 2026, data cutoff March 6, 2026). Abemaciclib after a CDK4/6 inhibitor is investigational.
Is iza-bren approved?
No. Iza-bren is investigational. In PANKU-Breast01, PFS by BICR was 8.18 vs 4.01 months (HR 0.41, 95% CI 0.33-0.53) vs chemotherapy, with OS immature (ESMO 2026 LBA50 abstract).
What breast cancer sessions are left at ESMO 2026?
On Monday, October 26: Rapid oral 2 on advanced breast cancer (10:15-11:45 Madrid time), including the OptiTROP-Breast01 final OS analysis, BRIDGET and a DESTINY-Breast09 brain metastases analysis; and a special symposium on biomarkers in early breast cancer (14:45-16:15). On Tuesday, October 27, Giuseppe Curigliano presents the breast cancer congress highlights (11:40-12:20).
KOL Pulse tracks what oncologists and hematologists post on X. Posts quoted here are shown in full, verbatim, and link to their source. Trial figures come from KOL Pulse trial pages, with the source and data cutoff in parentheses.
