Oncolytic adenovirus coding for bispecific T cell engager against human MUC-1 potentiates T cell response against solid tumors

Immunotherapy with bispecific T cell engagers has shown effi-cacy in patients with hematologic malignancies and uveal mel- anoma. Antitumor effects of bispecific T cell engagers in most solid tumors are limited due to their short serum half-life and insufficient tumor concentration. We designed a novel serotype 5/3 oncolytic adenovirus encoding a human mucin1 antibody and the human CD3 receptor, Ad5/3-E2F-d24-aMUC1aCD3 (TILT-321). TILT-321 is engineered to replicate only in cancer cells, leading to a high concentration of the aMUC1aCD3 mole - cule in the tumor microenvironment. Infection and cell viability assays were performed to determine the oncolytic potential of the novel construct. The functionality of the virus-derived aMUC1aCD3 was evaluated in vitro. When TILT-321 was combined with allogeneic T cells, rapid tumor cell lysis was observed. TILT-321-infected cells secreted func- tional aMUC1aCD3, as shown by increased T cell activity and its binding to MUC1 and CD3. In vivo, TILT-321 treatment led to effective antitumor efficacy mediated by increased intra- tumoral T cell activity in an A549 and patient-derived ovarian cancer xenograft mouse model humanized with peripheral blood mononuclear cells (PBMC). This study provides a proof of concept for an effective strategy to overcome the key limita- tions of recombinant bispecific T cell engager delivery for solid tumor treatment.

Automated summary

This study introduces a novel oncolytic adenovirus, TILT-321, which can replicate in cancer cells and produce a high concentration of aMUC1aCD3 molecules. TILT-321 demonstrated efficient tumor cell lysis and enhanced T cell activity in vitro and in a mouse model. The results provide a proof of concept for an effective strategy to overcome limitations in delivering bispecific T cell engagers for solid tumor treatment.