📬 Breast Cancer Intelligence Digest — Week 2026-W28

SUBITO shows olaparib-based chemo matches intensified transplant chemo in HRD stage III breast cancer, HORIZON-Breast01 reports striking PFS with trastuzumab rezetecan in HER2+ MBC, and 20-year EORTC 22922/10925 nodal RT data show no overall survival benefit in node-negative disease.

⚡ TL;DR

📄 Publications

Targeting homologous recombination deficiency with intensified chemotherapy versus standard chemotherapy followed by olaparib in stage III breast cancer (SUBITO): an open-label, randomised, controlled, phase 3 trial. — 4-year OS 77.0% (IACT) vs 76.4% (olaparib), HR for death 1.11
Trastuzumab rezetecan versus pyrotinib plus capecitabine for patients with HER2-positive metastatic breast cancer (HORIZON-Breast01): interim analysis of a multicentre, open-label, randomised, controlled, phase 3 trial. — Median PFS 30.6 vs 8.3 months, HR 0.22
Neoadjuvant stereotactic body radiation therapy with durvalumab and oleclumab in ER+HER2- breast cancer: a randomized phase 2 trial. — pCR rates 16.7%, 29.4%, 33.3% across arms (P=0.059)

🐦 Twitter / 🦋 Bluesky

Update: Neo-CheckRay published in Nature Medicine draws clinician debate on SBRT-immunotherapy in ER+/HER2- disease — Adding durvalumab, with or without CD73 blockade, improved pCR rates compared with iSBRT alone, particularly in PD-L1-negative tumors
European Commission approves T-DXd as first tumor-agnostic HER2-directed ADC — EC approved trastuzumab deruxtecan as the first tumor-agnostic HER2-directed ADC for previously treated HER2-positive (IHC 3+) solid tumors
HORIZON-Breast01: trastuzumab rezetecan tops pyrotinib plus capecitabine in HER2+ metastatic breast cancer — Median PFS 30.6 vs 8.3 months with a hazard ratio of 0.22
SUBITO: olaparib-based chemotherapy matches intensified transplant chemotherapy in stage III HRD breast cancer — 4-year OS was 77.0% with IACT and 76.4% with olaparib, HR for death 1.11 (p=0.37)

Full details below ↓

📄 What's Being Published

Manuscripts:

Targeting homologous recombination deficiency with intensified chemotherapy versus standard chemotherapy followed by olaparib in stage III breast cancer (SUBITO): an open-label, randomised, controlled, phase 3 trial. — Seefat Rianne L et al., Lancet Oncol

In this phase 3 trial, 174 patients were randomly assigned to receive intensified alkylating chemotherapy with autologous stem cell rescue (IACT; n=87) or standard chemotherapy followed by olaparib (n=87) for stage III HER2-negative HRD breast cancer. The 4-year overall survival was 77.0% (95% CI 67.7–87.7) in the IACT group and 76.4% (95% CI 66.9–87.4) in the olaparib group, with a hazard ratio for death of 1.11 (95% CI 0.57–2.17; p=0.37), indicating no statistically significant difference between arms.

Clinical bottom line: Intensified alkylating chemotherapy with autologous stem cell rescue offers no survival advantage over conventional chemotherapy plus olaparib in stage III HER2-negative HRD breast cancer, favoring the less toxic olaparib-based regimen.

Read full article →

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Trastuzumab rezetecan versus pyrotinib plus capecitabine for patients with HER2-positive metastatic breast cancer (HORIZON-Breast01): interim analysis of a multicentre, open-label, randomised, controlled, phase 3 trial. — Yao Herui et al., Lancet Oncol

Among 287 patients randomly assigned to trastuzumab rezetecan (n=142) or pyrotinib plus capecitabine (n=145) in previously treated HER2-positive metastatic breast cancer, median progression-free survival was 30.6 months (95% CI 16.8–NR) versus 8.3 months (95% CI 6.9–11.0), with a hazard ratio of 0.22 (95% CI 0.15–0.34; p<0.0001). The 12-month progression-free survival rate was 84.7% (95% CI 77.0–90.0) in the trastuzumab rezetecan group versus 35.5% (95% CI 26.8–44.2) in the control group.

Clinical bottom line: Trastuzumab rezetecan more than tripled progression-free survival versus pyrotinib plus capecitabine in previously treated HER2-positive metastatic breast cancer, presenting a potential new second-line treatment option.

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Neoadjuvant stereotactic body radiation therapy with durvalumab and oleclumab in ER+HER2- breast cancer: a randomized phase 2 trial. — De Caluwé Alex et al., Nat Med

In this randomized phase 2 trial (Neo-CheckRay), pCR rates were 16.7%, 29.4%, and 33.3% across the three treatment arms respectively (P=0.059), with the primary endpoint not met. Among PD-L1-negative tumors (n=91), pCR rates were 3.4%, 28.1%, and 30.0% respectively, suggesting a notable differential effect in immune-cold disease.

Clinical bottom line: Now published in Nature Medicine with author commentary, Neo-CheckRay suggests immune-modulating SBRT plus anti-PD-L1 may convert immune-cold ER+/HER2- breast cancer into inflamed tumors and improve pCR, particularly in PD-L1-negative disease, though the primary endpoint was not met.

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Internal mammary chain and medial supraclavicular lymph node irradiation in stage I-III breast cancer (EORTC trial 22922/10925): an unplanned subset analysis of 20-year outcomes in patients with node-negative breast cancer. — Kaidar-Person Orit et al., Lancet Oncol

At 20 years in this unplanned subset analysis of node-negative patients, overall survival was 69.0% (95% CI 65.4–72.3) in the internal mammary and medial supraclavicular (IM-MS) irradiation group versus 68.4% (95% CI 64.8–71.6) in the control group (HR 0.98 [95% CI 0.83–1.15], p=0.77). Breast cancer mortality was 10.0% (95% CI 8.0–12.3) in the IM-MS irradiation group versus 14.2% (95% CI 11.9–16.8) in the control group (HR 0.70 [95% CI 0.53–0.92], p=0.010).

Clinical bottom line: At 20 years, internal mammary and medial supraclavicular nodal irradiation reduced breast cancer mortality but conferred no overall survival benefit in node-negative disease, offset by numerically higher non-breast cancer mortality.

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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).

Update: Neo-CheckRay published in Nature Medicine draws clinician debate on SBRT-immunotherapy in ER+/HER2- disease

Adding durvalumab, with or without CD73 blockade, improved pCR rates compared with iSBRT alone, particularly in PD-L1-negative tumors — a subgroup where pCR rates reached 28.1% and 30.0% in the combination arms versus 3.4% with iSBRT alone. Despite the trial being formally negative on its primary endpoint, one investigator noted that Neo-CheckRay "shows intriguing results" and that the strategy may help reshape clinical practice, prompting debate among oncologists over whether immune-modulating radiation can reliably convert immune-cold ER+/HER2- tumors into responders.

Discussed by: @OncoAlert, @OncoAlert

→ View representative tweet

European Commission approves T-DXd as first tumor-agnostic HER2-directed ADC

The European Commission approved trastuzumab deruxtecan (ENHERTU®) as the first tumor-agnostic HER2-directed antibody-drug conjugate for patients with previously treated, unresectable or metastatic HER2-positive (IHC 3+) solid tumors, regardless of the tumor's site of origin. Because the approval is based on HER2 IHC 3+, which is not captured by NGS, clinicians are debating how labs should adapt testing workflows to proactively request HER2 IHC for patients who may be eligible.

Discussed by: @EladSharonMD, @ThePharmaLetter

→ View representative tweet

HORIZON-Breast01: trastuzumab rezetecan tops pyrotinib plus capecitabine in HER2+ metastatic breast cancer

In 287 randomized patients, trastuzumab rezetecan demonstrated a median PFS of 30.6 versus 8.3 months compared with pyrotinib plus capecitabine, with a hazard ratio of 0.22. Oncologists are debating whether these results position trastuzumab rezetecan as a new second-line HER2 ADC option beyond China, where the trial was conducted.

Discussed by: @OncoAlert, @FernandoOnco, @vcclibrary.bsky.social

→ View representative tweet

SUBITO: olaparib-based chemotherapy matches intensified transplant chemotherapy in stage III HRD breast cancer

The SUBITO trial reported 4-year overall survival of 77.0% with IACT and 76.4% with the olaparib-based regimen (HR for death 1.11; p=0.37), with intensified chemotherapy plus autologous stem cell rescue providing no advantage over standard chemotherapy plus olaparib. Clinicians are weighing whether olaparib-based conventional chemotherapy should now be the standard approach for stage III HER2-negative HRD breast cancer given equivalent survival and a more favorable toxicity profile.

Discussed by: @vcclibrary.bsky.social, @thelancetoncol.bsky.social

🔥 Top Ranked Tweets

OncoAlert @OncoAlert

RT @Dr_Ivanoncologo: A new era of precision oncology!

The European Commission has approved trastuzumab deruxtecan (ENHERTU®) as the first tumor-agnostic HER2-directed antibody-drug conjugate (ADC) for patients with previously treated, unresectable or metastatic HER2-positive (IHC 3+) solid tumors, regardless of the tumor's site of origin.

This landmark approval reinforces a key message: biomarker-driven treatment is reshaping cancer care, making comprehensive HER2 testing increasingly important across multiple solid tumors—not just breast or gastric cancer.

Link to read: https://t.co/BlDCsaDxdw

@OncoAlert @PortalOnconews
#Oncology #PrecisionMedicine #HER2 #ADC #ENHERTU #CancerResearch #TargetedTherapy

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