What are the American Society of Clinical Oncology (ASCO) guidelines for treating triple-negative breast cancer?

ASCO Guidelines for Triple Negative Breast Cancer Treatment

For patients with metastatic PD-L1-positive triple-negative breast cancer, ASCO strongly recommends immune checkpoint inhibitors (atezolizumab plus nab-paclitaxel or pembrolizumab plus chemotherapy) as first-line therapy. 1

First-Line Treatment Options

Metastatic TNBC

• PD-L1 positive tumors:

  • First-line: Immune checkpoint inhibitor plus chemotherapy 1, 2
    • Pembrolizumab plus chemotherapy (if CPS ≥10)
    • Atezolizumab plus nab-paclitaxel (not paclitaxel)
  • Evidence shows improved progression-free survival (PFS) and overall survival (OS) with these combinations
    • Atezolizumab + nab-paclitaxel: PFS 7.5 vs 5 months, OS 25 vs 15.5 months 1

• PD-L1 negative tumors:

  • Sequential single-agent chemotherapy is preferred over combination therapy 1, 2
  • First-line options:
    • Taxanes (paclitaxel preferred)
    • Anthracyclines (if not previously used)
    • Platinum agents (especially for BRCA mutation carriers)

Early-Stage TNBC

• Neoadjuvant chemotherapy with anthracycline and taxane-based regimens 2
  • Addition of carboplatin improves event-free survival
  • Neoadjuvant pembrolizumab with chemotherapy improves event-free survival
• Post-neoadjuvant capecitabine shows benefit for disease-free and overall survival 2

Treatment Based on BRCA Status

• BRCA1/2 mutation carriers:
  • PARP inhibitors (olaparib or talazoparib) are preferred over chemotherapy 2
  • BRCA1 mutations are found in 7-16% of TNBC patients 2
  • Short-term survival may be better in BRCA1/2 mutation carriers (2-year OS: 95% vs 91%) 2

Subsequent Lines of Therapy

• After two or more prior therapies, sacituzumab govitecan is recommended 2
  • Improves PFS (5.6 vs 1.7 months) and OS (12.1 vs 6.7 months) compared to standard chemotherapy
• Other options include:
  • Eribulin
  • Capecitabine
  • Platinum agents if not previously used 1

Combination Chemotherapy Options

Combination chemotherapy may be considered in cases of visceral crisis, though sequential single agents are generally preferred 1:

• Doxorubicin/cyclophosphamide (AC)
• Epirubicin/cyclophosphamide (EC)
• Docetaxel and capecitabine
• Gemcitabine and paclitaxel
• Carboplatin with paclitaxel or albumin-bound paclitaxel 1

Monitoring and Follow-up

• Evaluate response after 2-3 cycles of chemotherapy using:
  • Clinical evaluation
  • Subjective symptom assessment
  • Blood tests
  • Repetition of initially abnormal radiologic exams 2
• Re-biopsy may be appropriate in cases of mixed response 2

Important Considerations

• TNBC has a higher risk of regional recurrence compared to other subtypes 3
• Resistance to chemotherapy can develop quickly, and benefits diminish with each subsequent line of therapy 1
• African-American women have three times higher risk of TNBC compared to non-black women 2
• TNBC is more common in younger patients (under age 40) 2

Surgical and Radiation Approaches

• Breast-conserving therapy with sufficient margins is appropriate for TNBC 3
• Radiation therapy is beneficial for TNBC management:
  • For the chest wall after mastectomy
  • For regional areas and breast after breast-conserving surgery 2, 3
• Sentinel node biopsy and axillary resection should be performed with caution due to higher regional recurrence rates 3