atezolizumab + letrozole + pelareorep

A combination therapy consisting of atezolizumab (a PD-L1 inhibitor), letrozole (an aromatase inhibitor), and pelareorep (an oncolytic virus). This regimen combines three distinct therapeutic approaches: 1. **Atezolizumab**: A humanized IgG1 monoclonal antibody that targets programmed cell death ligand 1 (PD-L1), blocking its interaction with PD-1 and CD80 receptors. This blockade enhances T-cell activity against tumor cells by removing the inhibitory effect that would otherwise suppress immune response. 2. **Letrozole**: An aromatase inhibitor that reduces estrogen production by blocking the enzyme aromatase, which converts anrogens to estrogens. This is particularly relevant in hormone-dependent cancers like breast cancer. 3. **Pelareorep**: A non-genetically modified reovirus (type 3 Dearing strain) that selectively infects and kills cancer cells while promoting tumor-directed immune responses. It increases T-cell infiltration and PD-L1 expression in tumors, potentially priming them for checkpoint inhibitor therapy. The combination likely aims to create synergistic anti-tumor effects by simultaneously targeting cancer cells through hormonal pathway inhibition, direct oncolytic activity, and enhancement of immune system recognition and attack of tumor cells.