Sustained disease-free survival in metastatic triple-negative breast cancer following CCR5 antibody leronlimab and atezolizumab: A case study

Metastatic triple-negative breast cancer (mTNBC) is associated with poor overall survival and limited treatment options especially in later lines of therapy and with tumors lacking PD-L1 tissue staining. We report on an Asian female diagnosed with stage IIA TNBC at age 40. She underwent bilateral mastectomy with an invasive ductal carcinoma on the left. Biopsies indicated CCR5 negativity in tumor cells but high CCR5 expression in leukocytes. Five percent of tumor cells and tumor infiltrating lymphocytes stained positive for PD-L1. She initially received adjuvant chemotherapy with dose-dense doxorubicin/cyclophosphamide followed by dose-dense paclitaxel. Subsequently an axillary lymph node dissection revealed a 0.7 cm implant. She was treated with capecitabine but was then diagnosed with lung metastases and underwent a right lung partial lobectomy. She then began therapy with atezolizumab and nab-paclitaxel, then added leronlimab, a CCR5 inhibitor, obtained through compassionate access. Subsequently she was diagnosed with brain metastases which were treated with parieto-occipital cortex stereotactic radiotherapy. The patient discontinued nab-paclitaxel but continued atezolizumab and leronlimab. Blood samples were analyzed for PD-L1 expression on cancer-associated macrophage-like cells and circulating tumor cells. These analyses showed that after receiving leronlimab the patient’s PD-L1 expression increased significantly. > 60 months after starting leronlimab in combination with atezolizumab the patient remains alive with no evidence of disease. This case of disease-free survival in mTNBC is unexpected given the rapidity of disease recurrence during her standard-of-care adjuvant treatment. This case highlights the potential for CCR5 inhibition in combination with an ICI for treatment of mTNBC.