📬 Breast Cancer Intelligence Digest — Week 2026-W30

FDA approves gedatolisib for PIK3CA wild-type HR+/HER2- MBC while new data on camizestrant switching, real-world recurrence risk, ASCO surveillance guidelines and negative HER2CLIMB-04 dominate breast oncology discussion.

⚡ TL;DR

📄 Publications

Impact of trop-2 expression on the efficacy of trop-2-targeted antibody-drug conjugates in metastatic breast cancer: a systematic review and meta-analysis. — ADC-T2 improved PFS in Trop-2-high (HR 0.34) and Trop-2-low (HR 0.63)
Breast Cancer Follow-Up and Surveillance After Primary Treatment: ASCO Guideline Update. — Risk-based approach to frequency and intensity of follow-up recommended
Progression-Free Survival in Metastatic Breast Cancer by Local Investigators vs Blinded Independent Central Review: A Systematic Review and Meta-Analysis. — No significant difference between investigator and BICR PFS, DI 1.02
Switching to camizestrant at ESR1 mutation emergence before disease progression during first-line treatment of hormone receptor-positive advanced breast cancer (SERENA-6): extended analysis of a double-blind, placebo-controlled, randomised, phase 3 trial. — Median PFS 16.8 vs 9.2 months, HR 0.45

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FDA approves gedatolisib plus fulvestrant ± palbociclib in PIK3CA wild-type HR+/HER2- MBC — Median PFS fulvestrant 2.0m, F+G 7.4m, F+G+palbo 9.3m
ASCO updates breast cancer surveillance guideline toward risk-adapted follow-up — Follow-up should be risk-adapted, not one-size-fits-all
SOFT and TEXT final 15-year outcomes in premenopausal HR+ early breast cancer — Exemestane + OFS should be prioritized for high-risk premenopausal patients
Real-world Flatiron data quantify recurrence risk in HR+/HER2- early breast cancer — 7-year recurrence rates 14% for N1 and N0 high-risk, up to ~40% in N2-3
Low-dose 5 mg tamoxifen IPD pooled analysis in DCIS and high-risk lesions — In postmenopausal women, 5 mg/day gave 49% fewer breast cancer events (HR 0.51)

Full details below ↓

📄 What's Being Published

Manuscripts:

Impact of trop-2 expression on the efficacy of trop-2-targeted antibody-drug conjugates in metastatic breast cancer: a systematic review and meta-analysis. — Buonaiuto Roberto et al., J Natl Cancer Inst

This meta-analysis found that Trop-2-targeted ADCs significantly improved PFS compared to chemotherapy in both Trop-2-high (HR 0.34, 95% CI 0.20–0.57) and Trop-2-low (HR 0.63, 0.50–0.79) subgroups across metastatic breast cancer. However, in HR+/HER2− mBC specifically, a significant PFS benefit was observed only in the Trop-2-high subgroup (HR 0.56, 0.47 to 0.68, p < 0.001), with no significant benefit demonstrated in Trop-2-low tumors of that subtype.

Clinical bottom line: Trop-2 ADCs benefit HR+/HER2− disease only in Trop-2-high tumors, and standardized Trop-2 assays are now the emphasis.

Read full article →

Breast Cancer Follow-Up and Surveillance After Primary Treatment: ASCO Guideline Update. — Nahleh Zeina et al., J Clin Oncol

The updated ASCO guideline offers recommendations on the role of a risk-based approach to the frequency and intensity of follow-up among patients with breast cancer in the adjuvant setting. Regular history, physical examination, and mammography are recommended for breast cancer follow-up, while routine tumor markers, advanced imaging, and ctDNA testing in asymptomatic patients are not endorsed.

Clinical bottom line: ASCO now endorses risk-adapted surveillance rather than uniform follow-up, and recommends against routine tumor markers, imaging, and ctDNA in asymptomatic patients.

Read full article →

🔗 Also discussed on social media →

Progression-Free Survival in Metastatic Breast Cancer by Local Investigators vs Blinded Independent Central Review: A Systematic Review and Meta-Analysis. — Ravani Lis Victoria et al., JAMA Oncol

Of 4,989 identified records, 21 RCTs with 9,165 patients met inclusion criteria for this meta-analysis comparing investigator- and BICR-assessed PFS. No statistically significant difference was observed between the two assessment methods overall, with a DI of 1.02 (95% CI, 0.95–1.10; P = .57).

Clinical bottom line: Investigator-assessed and BICR-assessed PFS produce comparable estimates in HR+/HER2− mBC, questioning mandatory BICR in registration trials.

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Current Management of Human Epidermal Growth Factor Receptor 2-Positive Breast Cancer in a Changing Landscape. — Lipsyc-Sharf Marla et al., J Clin Oncol

This review describes how trastuzumab deruxtecan (T-DXd) has demonstrated unprecedented efficacy and is rapidly moving earlier in treatment algorithms across both metastatic and curative-intent settings. The shift raises practical questions around treatment sequencing and ILD management as HER2-positive metastatic breast cancer is increasingly managed over extended time horizons.

Clinical bottom line: HER2-positive metastatic breast cancer is increasingly managed for years, with T-DXd moving earlier and raising sequencing and ILD-management questions.

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Switching to camizestrant at ESR1 mutation emergence before disease progression during first-line treatment of hormone receptor-positive advanced breast cancer (SERENA-6): extended analysis of a double-blind, placebo-controlled, randomised, phase 3 trial. — Turner Nicholas C et al., Lancet Oncol

In this extended analysis of SERENA-6, median progression-free survival was 16.8 months (95% CI 14.7–19.4) with camizestrant plus CDK4/6 inhibitor versus 9.2 months (7.2–9.7) with aromatase inhibitor plus CDK4/6 inhibitor (HR 0.45 [95% CI 0.34–0.59]; nominal p<0.0001). Median second progression-free survival was 25.7 months (95% CI 20.4–30.3) versus 19.1 months (16.8–21.0); HR 0.63 (0.46–0.86; p=0.0037), confirming durability of benefit across sequential treatment lines.

Clinical bottom line: Extended analysis confirms ctDNA-guided switching to camizestrant at ESR1 emergence sustains PFS benefit and now shows a significant second-PFS improvement.

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Comprehensive clinical cancer analysis of homologous recombination deficiency biomarkers in an academic molecular profiling program. — Domènech Heura et al., NPJ Precis Oncol

Longitudinal ctDNA sequencing revealed BRCA1/BRCA2 reversion mutations in >30% of post-PARPi mBC samples, and these mutations were associated with poor response to subsequent platinum therapy. The findings support integrating complementary HRD biomarkers from both tissue and liquid biopsy to detect deficiency missed by mutation testing alone.

Clinical bottom line: Complementary HRD biomarkers in tissue and liquid biopsy detect deficiency missed by mutation testing and reveal frequent BRCA reversion after PARPi.

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Recurrence risk in HR-positive/HER2-negative early breast cancer: real-world US electronic health records study. — Tarantino Paolo et al., J Natl Cancer Inst

In this Flatiron real-world analysis, both NATALEE- and monarchE-eligible populations showed relatively high 5-year distant recurrence rates (DRFS 83.1% and 74.6%, respectively). Notably, the N0 high-risk subgroup showed overall and distant recurrence and mortality risks similar to those in the N1 subgroup.

Clinical bottom line: Real-world Flatiron data confirm meaningful recurrence risk across HR+/HER2− early breast cancer regardless of nodal status, supporting adjuvant CDK4/6i use.

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Avutometinib, Abemaciclib, and Fulvestrant in Patients with HR+/HER2- Metastatic Breast Cancer Previously Treated with CDK4/6 Inhibitor: A Single-Arm Phase I Trial. — Waks Adrienne G et al., Clin Cancer Res

In this phase I trial, the avutometinib/abemaciclib/fulvestrant triplet yielded an ORR of 13% (2/15 patients with measurable disease), a 24-week CBR of 40% (6/15 patients with measurable disease), and a median PFS of 3.6 months (95% CI: 2.1–not reached) in patients previously treated with a CDK4/6 inhibitor.

Clinical bottom line: The avutometinib/abemaciclib/fulvestrant triplet was well tolerated at RP2D with preliminary activity after CDK4/6i progression, and a phase II trial is ongoing.

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Tumor infiltrating lymphocytes as a predictor of adjuvant avelumab efficacy in patients with high-risk triple negative breast cancer. — Dieci Maria Vittoria et al., Clin Cancer Res

In the A-BRAVE trial, avelumab improved outcomes only for patients with BSL-TILs ≥30%, particularly in Stratum B, where 3-year DDFS rates were 92.0% vs 58.7% (HR 0.20) in high BSL-TILs patients versus 70.4% vs 70.1% (HR 0.92) in low BSL-TILs patients (interaction p=0.019). No benefit was observed in the low TILs subgroup.

Clinical bottom line: In the A-BRAVE trial, TILs predicted benefit from adjuvant avelumab in high-risk early TNBC, supporting TILs-guided immunotherapy strategies.

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🗣️ What People Were Discussing This Week

How these are chosen: filtered for clinical relevance, grouped by the new development discussed, then ordered by engagement (bookmarks and reposts).

FDA approves gedatolisib plus fulvestrant ± palbociclib in PIK3CA wild-type HR+/HER2− MBC

The FDA approved gedatolisib as second-line therapy in combination with fulvestrant for tumors without PIK3CA mutations, with median PFS of 2.0 months for fulvestrant alone, 7.4 months for fulvestrant plus gedatolisib, and 9.3 months for the triplet with palbociclib. The PFS improvement over fulvestrant was similar with or without palbociclib (HR 0.24, HR 0.33, with overlapping 95% CI), prompting debate among oncologists over whether the doublet should be preferred over the triplet given the added toxicity and IV burden of the three-drug regimen.

Discussed by: @stolaney1, @kazuki_nozawa, @OncBrothers, @OncBrothers, @AlexisLeVee, @EladSharonMD

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ASCO updates breast cancer surveillance guideline toward risk-adapted follow-up

The updated ASCO guideline establishes that follow-up should be risk-adapted, not one-size-fits-all, moving away from uniform surveillance protocols in the adjuvant setting. ctDNA surveillance outside clinical trials is explicitly not recommended, and clinicians are debating how to handle patient-requested ctDNA testing in routine practice.

Discussed by: @OncoAlert, @Dr_Oncologista, @JaniceTNBCmets

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SOFT and TEXT final 15-year outcomes in premenopausal HR+ early breast cancer

Final 15-year SOFT and TEXT data reinforce that premenopausal patients face very high long-term distant recurrence risk, and that exemestane plus OFS should be prioritized for high-risk premenopausal HR+/HER2− breast cancer, while treatment de-escalation remains reasonable for lower-risk disease. Oncologists are weighing how these mature data should guide escalation and de-escalation of endocrine therapy decisions by individual patient risk profile.

Discussed by: @DFCI_BreastOnc, @Dr_Oncologista, @EladSharonMD

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Real-world Flatiron data quantify recurrence risk in HR+/HER2− early breast cancer

Real-world data from Flatiron electronic health records report 7-year recurrence rates of 14% for N1 and N0 high-risk patients and up to ~40% in N2–3, supporting use of adjuvant CDK4/6i. The N0 high-risk subgroup showed overall and distant recurrence and mortality risks similar to those in the N1 subgroup, with the central question being whether this risk profile justifies broader adjuvant CDK4/6 inhibitor use regardless of nodal status.

Discussed by: @stolaney1, @PTarantinoMD

→ View representative tweet

Low-dose 5 mg tamoxifen IPD pooled analysis in DCIS and high-risk lesions

A pooled individual patient data analysis of low-dose tamoxifen at 5 mg/day showed 49% fewer breast cancer events (HR 0.51) in postmenopausal women, while a reduction in contralateral breast cancer was still observed in premenopausal women (HR 0.45). Clinicians are assessing whether low-dose tamoxifen is a viable de-escalation strategy and whether the benefit differential by menopausal status should shape prescribing.

Discussed by: @ChandrakanthMv, @EladSharonMD

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HER2CLIMB-04: adding tucatinib to T-DXd fails to improve efficacy

Results from HER2CLIMB-04 show that combining T-DXd with tucatinib does not lead to higher efficacy than T-DXd monotherapy. Among 70 patients, the combination achieved a confirmed objective response rate of 51.4%, median duration of response of 11.9 months, and progression-free survival of 11.5 months — results that specialists are comparing to T-DXd alone and asking whether tucatinib is a poor partner for HER2-directed ADCs, given the parallel lack of benefit seen in HER2CLIMB-02.

Discussed by: @kazuki_nozawa, @Dr_Oncologista

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SONIA 5-year OS: timing of CDK4/6 inhibition does not improve survival

Five-year overall survival data from SONIA showed median OS of 47.9 vs 48.1 months (HR 0.91, 95% CI 0.77–1.07; P=.24), with no significant difference by timing of CDK4/6 inhibitor initiation. An exploratory subgroup analysis identified a potential OS benefit in premenopausal patients (HR 0.53), prompting discussion of whether first-line CDK4/6i can be deferred to second line in selected patients without compromising survival.

Discussed by: @ChandrakanthMv, @EladSharonMD

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Extending ovarian-suppression endocrine therapy beyond 5 years in premenopausal HR+ disease

Data on extended ovarian-suppression endocrine therapy in premenopausal HR+ disease showed a 37% lower risk of invasive recurrence (HR 0.63; P=0.0135) and a 51% lower risk of distant recurrence (HR 0.49; P=0.0033) with continuation beyond 5 years. Oncologists are debating whether high-risk premenopausal patients who are disease-free after 5 years of ovarian-suppression therapy should extend treatment, balanced against the cumulative burden of prolonged endocrine therapy.

Discussed by: @ChandrakanthMv, @EladSharonMD

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🔥 Top Ranked Tweets

Sara Tolaney @stolaney1

RT @DFCI_BreastOnc: Final outcomes of the SOFT and TEXT phase III trials in premenopausal hormone receptor-positive early #BreastCancer.
🔓https://t.co/ZOcxC4HFOr
@DrHBurstein @puglisi_fabio @mpgoetz @VeredStearns @DrEricWiner @Annals_Oncology https://t.co/Sw0L1Cu9NK

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