From the Guidelines
Patients with metastatic triple-negative breast cancer without expression of programmed cell death ligand-1 (PD-L1–negative) should be offered single-agent chemotherapy rather than combination chemotherapy as first-line treatment. This approach is based on the most recent guideline update from the Journal of Clinical Oncology in 2021 1, which provides a strong recommendation with moderate evidence quality. The benefits of single-agent chemotherapy outweigh the harms, making it the preferred treatment option for PD-L1–negative metastatic triple-negative breast cancer.
When considering treatment options for triple-negative breast cancer (TNBC), it's essential to prioritize morbidity, mortality, and quality of life. TNBC is a challenging subtype of breast cancer, lacking expression of estrogen receptors, progesterone receptors, and HER2 protein. Treatment typically involves a multimodal approach, including surgery, chemotherapy, and radiation therapy. However, for patients with metastatic disease, the focus shifts to controlling symptoms and improving survival.
Key considerations for treating metastatic TNBC include:
- Symptomatic or immediately life-threatening disease may require combination regimens, despite the preference for single-agent chemotherapy
- PD-L1 status is crucial in determining the suitability of immunotherapy with pembrolizumab
- Patients with BRCA mutations may benefit from PARP inhibitors like olaparib
- Sacituzumab govitecan (Trodelvy) has shown effectiveness in metastatic TNBC, offering an additional treatment option
The guideline update from 2021 1 emphasizes the importance of evidence-based decision-making in the treatment of metastatic TNBC. By prioritizing single-agent chemotherapy for PD-L1–negative patients, clinicians can optimize treatment outcomes and minimize harm. Regular follow-ups and consideration of clinical trials are also essential in managing this aggressive and challenging cancer subtype.
From the Research
Characteristics of Triple Negative Breast Cancer
- Triple negative breast cancer (TNBC) is characterized by the lack of expression of estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptors (HER2) 2, 3, 4, 5, 6
- TNBC is a particularly aggressive form of breast cancer that generally displays poorer prognosis compared to other breast cancer subtypes 4
- TNBC tends to grow rapidly and has poor outcomes, with a high recurrence rate and a short interval between recurrence and death 2
Treatment Options for Triple Negative Breast Cancer
- Chemotherapy is the most common treatment option for TNBC, with anthracyclines and taxanes being commonly used drugs 3, 5, 6
- Neoadjuvant chemotherapy with platinum-based regimens has been shown to be effective for TNBC 2, 5
- Radiation therapy has been shown to be useful for the management of TNBC, particularly after breast-conserving surgery or mastectomy 2
- Immunotherapy, targeted therapy, and nanoparticle-based therapy are potential future treatment options for TNBC 3, 4, 5
Challenges and Limitations of Treatment
- Developing resistance to anticancer drugs and off-target toxicity are primary hindrances to chemotherapeutic solutions for TNBC 3
- TNBC is characterized by various molecular subtypes, making treatment challenging 3
- Only a fraction of patients with TNBC respond to immune checkpoint or PARP inhibitors, and even those who do respond often develop resistance and relapse 4