Therapy of Established Tumors with Rationally Designed Multiple Agents Targeting Diverse Immune-Tumor Interactions: Engage, Expand, Enable

ABSTRACT: Immunotherapy of immunologically cold solid tumors may require multiple agents to (a) engage immune effector cells, (b) expand effector populations and activities, and (c) enable immune response in the tumor microenvironment (TME). To target these distinct phenomena, we strategically chose five clinical-stage immuno-oncology agents, namely, (a) a tumor antigen-targeting adenovirus-based vaccine (Ad-CEA) and an IL-15 superagonist (N-803) to activate tumor specific T cells, (b) OX40 and GITR agonists to expand and enhance the activated effector populations, and (c) an IDO inhibitor (IDOi) to enable effector cell activity in the TME. Flow cytometry, TCR sequencing, and RNAseq analyses showed that in the CEA-transgenic murine colon carcinoma (MC38-CEA) tumor model, Ad-CEA + N-803 combination therapy resulted in immune-mediated anti-tumor effects and promoted the expression of costimulatory molecules on immune subsets, OX40 and GITR, and the inhibitory molecule IDO. Treatment with Ad-CEA + N-803 + OX40 + GITR + IDOi, termed the pentatherapy regimen, resulted in the greatest inhibition of tumor growth and protection from tumor rechallenge without toxicity. Monotherapy with any of the agents had little to no anti-tumor activity, while combining two, three, or four agents had minimal anti-tumor effects. Immune analyses demonstrated that the pentatherapy combination induced CD4+ and CD8+ T cell activity in the periphery and tumor and anti-tumor activity associated with decreased Treg immunosuppression in the TME. The pentatherapy combination also inhibited tumor growth and metastatic formation in 4T1 and LL2-CEA murine tumor models. Significance: This study provides the rationale for the combination of multi-modal immunotherapy agents to engage, enhance, and enable adaptive anti-tumor immunity.

ORGANISM(S): Mus musculus

PROVIDER: GSE162799 | GEO | 2021/02/10

REPOSITORIES: GEO