Benjamin Walbaum, Medical Oncologist at Pontifical Catholic University of Chile, shared a post on LinkedIn:
“Breast Cancer Weekly Highlights | November 17–23, 2025
My personal selection of the most relevant scientific data published this week.
1. Biomarkers of Response to Trastuzumab Deruxtecan (DESTINY-Breast 01/02/03 Pooled Analysis)
- Response correlated with long-term outcomes.
- CR had outstanding survival.
- Endocrine-resistant sig (e.g., ESR1mut) less common in responders.
- Toxicity not associated with response.
Annals of Oncology.
2. Mixed Molecular Subtypes Coexist in ER-Heterogeneous Primary BC.
- ER-heterogeneous tumors contain mixed Lum A and B regions; no basal-like compartment.
- ER-neg pockets show endocrine-resistant but chemotherapy-sensitive biology.
- Neoadjuvant CT preferentially eliminates ER-low regions.
Journal of Clinical Oncology.
3. Field Cancerization, Accelerated Aging and Immunosuppression in HR+ BC A unifying biological explanation for the global rise in early-age and HR+ BC
- Endocrine-disrupting chemicals (EDCs) accelerate ‘hormonal aging’ of breast tissue.
- Environmental exposures create large ‘cancerized fields.’
- Vulnerable developmental windows include in-utero life, puberty, and pregnancy.
NPJ Breast Cancer.
4. HER2CLIMB-02: Tucatinib + T-DM1 in Previously Treated HER2+ MBC
Phase III study showing meaningful PFS improvement, including in patients with brain metastases.
- PFS: 9.5 vs 7.4 months (HR 0.75).
- No OS benefit at the time of analysis.
- TRAE ≥3 higher with tucatinib + T-DM1 (68.8% vs 41.2%).
- Hepatic toxicity dominant: ALT/AST ≥3 in 16.5% vs 2.6%.
Annals of Oncology.
5. ctDNA-Based Early Switch Therapy: From PADA-1 to SERENA-6.
- Early switch from AI to fulvestrant (PADA-1) significantly improves PFS.
- SERENA-6 extends this concept using oral SERDs.
Breast Cancer Research and Treatment.
6. Prognostic Impact of BRCA1/2 Variant Type and Location in YW
International cohort of 3,294 women <40 with BRCA variants.
- Missense variants to better OS (BRCA1 HR 0.48; BRCA2 HR 0.17)
- Protein-truncating BRCA1 variants → worse OS (HR 2.0).
- Specific exon predict aggressiveness (BRCA1) or earlier onset (BRCA2 exon 10).
Annals of Oncology.
7. Breast Surgery for Metastatic Breast Cancer (Cochrane Review)
5 RCTs (n=1368).
- Surgery improves local control.
- – No OS benefit for de novo metastatic patients.
- – Possible OS benefit in luminal tumors (exploratory).
Cochrane Database of Systematic Reviews.
8. Post-Neoadjuvant T-DM1 in HER2+ Early BC (Institut Curie)
RW outcomes for patients with RD.
- 4-year DFS 92.5%; distant recurrence 7%.
- CNS relapse dominant (71% of distant events).
- No cN0 patient recurred; all events occurred in cN+ disease (p = 0.025).
Scientific Reports.
9. Kinetics and Determinants of ESR1mut Detection (PADA-1)
ESR1mut accumulate progressively during AI + CDK4/6i.
- ESR1mut emergence peaks 6–36 months into therapy.
- Early switch to fulvestrant doubled PFS (12.8 vs 5.9 months, HR 0.54).
- PFS2 improved (29.4 vs 14.0 months, HR 0.35).
Annals of Oncology.”
More posts featuring Benjamin Walbaum.
