Durable response in a patient with recurrent respiratory papillomatosis treated with immune checkpoint blockade

Background Immune checkpoint blockade can provide clinical benefit for patients with advanced cancer. Here, we report durable disease control over many years following PD-L1 blockade through induction of a viral antigen-specific T cell response in an adult patient with recurrent respiratory papillomatosis. Methods Antigen-specific T cell response assays, single cell RNA-sequencing, and RNA-scope was used to study clinical tissues. Results An HPV6 E2-specific T cell clone restricted to HLA-B*55, present at low frequency in the pre-treatment papilloma, significantly expanded after six doses of PD-L1 blockade and remained present and functional at the site of initial response in the larynx as a tissue resident memory T cell for 4 years. An associated reduction in E2 target gene was observed following treatment. Conclusions Although demonstrated in a single exceptional responder, these results highlight that immune checkpoint blockade may induce durable, viral antigen-specific immunity of sufficient magnitude to control disease in patients with nonmalignant disorders.