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William J. Gradishar, MD, FACP, FASCO


Do All Subtypes of Triple-Negative Breast Cancer Respond to Atezolizumab?

By: Julia Fiederlein Cipriano, MS
Posted: Wednesday, November 22, 2023

Patients with a proliferative basal subtype of early-stage triple-negative breast cancer seemed to benefit from neoadjuvant chemotherapy in combination with the anti–PD-L1 antibody atezolizumab, according to Carlos H. Barrios, MD, of Hospital São Lucas da PUCRS, Porto Alegre, Brazil, and colleagues. Presented during the European Society for Medical Oncology (ESMO) Congress 2023 (Abstract 2232O), this biomarker analysis of the IMpassion031 trial nevertheless indicated reduced activity in those with indolent luminal androgen receptor tumors.

The investigators examined tumor tissue samples from patients who received chemotherapy plus either atezolizumab or a placebo. Atezolizumab appeared to numerically improve the pathologic complete response rate, as well as event-free, disease-free, and overall survival, in those with tumor infiltrating lymphocyte–low tumors.

Both patients with basal-like immune-activated and -suppressed tumors demonstrated a higher pathologic complete response rate with atezolizumab; however, this did not seem to hold true in those with tumors of the luminal androgen receptor subtype. Event-free and disease-free survival benefits with atezolizumab were exclusively seen in patients with basal-like immune activated tumors; only those with basal-like immune-suppressed tumors demonstrated improved overall survival. The investigators reported “excellent” event-free, disease-free, and overall survival in patients with luminal androgen receptor tumors, irrespective of the treatment approach, in contrast to a “relatively low” pathologic complete response rate.

Increased proliferation, gamma delta T cells, and pro-B cells were found to be predictive of improved pathologic complete responses with atezolizumab; epithelial-mesenchymal transition, pericytes, and stromal biology did not appear to be associated with such a benefit. No biologic pathway or cell type seemed to consistently predict survival benefits with atezolizumab. According to the investigators, exposure to chemotherapy with and without atezolizumab promoted dynamic changes in the molecular subtype, which returned to baseline at disease recurrence.

“Further studies are needed to validate these findings,” the investigators concluded.

Disclosure: For full disclosures of the study authors, visit

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