Mitigating the immunosuppressive effects of surgery in combination with photodynamic therapy via immune checkpoint inhibition

Although commonly employed in combination with other modalities for treatment of cancer, surgery produces an immunosuppressive effect that can impede the effectiveness of accompanying therapy. This includes for treatment regimens that incorporate debulking surgery prior to delivery of photodynamic therapy (PDT). We have shown that PDT can partially reverse the upregulation of immune checkpoint molecules introduced by surgery in the tumor environment. However, this effect of PDT is incomplete. We now report that PD-1 blockade will mitigate the immunosuppressive environment and rescue the potential for a curative response in treatment regimens that add immunotherapy to PDT of a surgically-inflamed tumor resection site.