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NCCN 2.2026ESMO Living GuidelinesLast reviewed: Apr 2026

Triple-Negative Breast Cancer (TNBC): Treatment GuidelinesBiomarker-First. Stage-Adapted. Evidence-Driven.

Your patient has TNBC — does PD-L1 status matter neoadjuvantly? And when disease becomes metastatic, which biomarker do you test first? This guide covers every decision point from early-stage KEYNOTE-522 to post-KN522 recurrence strategies.

64.8%
pCR KN-522
vs 51.2% placebo
HR 0.66
5-yr OS Benefit
KEYNOTE-522
CPS ≥10
Key mTNBC cutoff
1L IO decision
3 ADCs
Active in mTNBC
SG · T-DXd · Dato-DXd
Overview · TNBC Definition

What Is Triple-Negative Breast Cancer?

Definition:TNBC is defined by the absence of estrogen receptor (ER), progesterone receptor (PR), and HER2 amplification (ER <1%, PR <1%, HER2 IHC 0–1+ or 2+/ISH−). It represents ~15–20% of all breast cancers and carries the highest short-term risk of recurrence and death.

15–20%
Proportion of BC
All breast cancers
~40%
5-yr Recurrence Risk
Early-stage, node-positive
~30%
Brain Mets Rate
Higher than other subtypes
  • gBRCA1/2: Present in ~15–20% of TNBC; germline testing mandatory for all TNBC — determines PARP inhibitor eligibility (neoadjuvant and metastatic settings)
  • PD-L1 CPS: CPS ≥10 required for first-line IO combination in metastatic setting; NOT required neoadjuvantly (KEYNOTE-522 benefit regardless of PD-L1)
  • HER2-low (IHC 1+ or 2+/ISH−): Occurs in ~50% of "HER2-0" TNBC on re-biopsy; unlocks T-DXd eligibility (DESTINY-Breast04) in later lines
  • TROP2: Highly expressed in ~90% of TNBC; target of sacituzumab govitecan (SG) and datopotamab deruxtecan (Dato-DXd)
Overview · Treatment Sequence

2026 TNBC Treatment Sequence Overview

1

Neoadjuvant (Stage II–III)

KEYNOTE-522: Carboplatin/Paclitaxel + Pembrolizumab (q3w) × 4 → Doxorubicin/Cyclophosphamide + Pembrolizumab × 4 → Surgery

All eligible Stage II–III TNBC regardless of PD-L1 status

2

Non-pCR Residual Disease

Continue adjuvant Pembrolizumab (9 cycles total). Add Olaparib (gBRCA+, CPS+EG ≥3) OR Capecitabine (BRCA wild-type)

Adjuvant Pembrolizumab = 9 adjuvant cycles; total 17 cycles including neoadjuvant

3

Metastatic 1L — PD-L1+ (CPS ≥10)

SG + Pembrolizumab (ASCENT-04) Category 1 Preferred; alternative: KN-355 (chemo + pembro)

Re-test PD-L1 on metastatic biopsy — do not use archival

4

Metastatic 1L — PD-L1 Negative / ICI-Ineligible

Dato-DXd (TROPION-Breast02; stronger OS signal) or SG (ASCENT-03). gBRCA+: PARP inhibitor

Dato-DXd PDUFA: June 2, 2026; anticipated as first TROP2-ADC approved 1L mTNBC

5

Subsequent Lines (2L+)

T-DXd if HER2-low (DESTINY-Breast04). Alternate TROP2 ADC. Traditional chemo (Capecitabine, Eribulin, Vinorelbine)

ADC after ADC: cross-resistance risk (both SG + Dato-DXd use TopoI payloads) — switch mechanism where possible

Clinical Decision Support

Integrated Clinical Calculators

Use these validated tools at the point of care to support treatment planning and patient evaluation in TNBC.

ECOG Performance StatusCharlson Comorbidity IndexG8 Geriatric ScreeningCARG Chemotherapy ToxicityKhorana VTE Risk ScoreKEYNOTE-522 Eligibility Check

Related Breast Cancer Guidelines

HER2-Positive Breast Cancer
Pertuzumab, T-DM1, T-DXd, tucatinib — HER2-targeted treatment algorithms
HR+ / HER2− Breast Cancer
CDK4/6 inhibitors, endocrine therapy, PI3K/AKT pathway — early and metastatic
Clinical Disclaimer: This content is intended for qualified healthcare professionals and is provided for informational purposes only. Treatment decisions must account for individual patient circumstances, institutional protocols, drug availability, and updated literature. Always refer to current NCCN, ESMO, and institutional guidelines. OncoToolkit assumes no liability for clinical decisions made on the basis of this content.