Small-cell breast carcinoma with response to atezolizumab: a case report.

Background: Small-cell carcinoma of the breast is a rare disease with little research outlining molecular targets or optimal therapeutic management. We summarize a young female patient with poorly differentiated high-grade carcinoma with neuroendocrine features/small-cell carcinoma. Case presentation: A 31-year-old female presented with a large left breast mass. Initial biopsy revealed small-cell, triple-negative breast carcinoma. Treatment consisted of cisplatin and etoposide but was poorly tolerated and discontinued after one cycle. Combination abraxane/atezolizumab resulted in transient partial response in tumor size with 7 months of progression-free stability. Worsening metastatic disease was found 8 months after initial biopsy on radiologic studies and the patient expired 10 months after initial biopsy. Conclusion: Transient benefit in response to combination abraxane/atezolizumab was demonstrated.