Research paperThe combination of NK and CD8+Â T cells with CCL20/IL15-armed oncolytic adenoviruses enhances the growth suppression of TERT-positive tumor cells

- We constructed a CCL20/IL15 co-expression conditionally replicating adenovirus.
- CRAd-CCL20-IL15 could selectively replicate in TERT-positive tumor cells.
- Combination of CIK and CRAd-CCL20-IL15 could induce higher antitumor activity.
- The combined therapy of CIK and CRAd-CCL20-IL15 resulted in tumor regression.
- Combination of immunotherapy and oncolytic adenovirus enhanced antitumor activity.

Adoptive immunotherapy and targeted gene therapy have been extensively used to eliminate tumor cells. The combination treatment is capable of efficiently generating an effective antitumor immune response and disrupting tumor-induced tolerance. Moreover, effective antitumor immune responses are dependent on coordinate interaction among various effector cells. This study focused on whether the combination of cytotoxic effector cell-based adoptive immunotherapy and CCL20/IL15-armed oncolytic adenoviruses could induce enhanced antitumor activity. The CCL20/IL15-armed oncolytic adenovirus was constructed using homologous recombination with shuttle plasmids and full-length Ad backbones. We chose the telomerase reverse transcriptase promoter (TERTp) to replace the E1A promoter to drive the oncolytic adenoviral E1A gene. Thus, this CRAd-CCL20-IL15 could induce apoptosis in TERTp-positive tumor cells due to viral propagation, but these viruses could not replicate efficiently in normal cells. The combination of cytotoxic effector cells and CRAd-CCL20-IL15 showed greater antitumor potential than that of cytotoxic effector cells or CRAd-CCL20-IL15 alone. Moreover, the combined treatment could induce tumor-specific cytotoxicity of CTLs in vitro. Further analysis demonstrated that this combined treatment resulted in significant tumor regression in mouse models. This study has provided preclinical evidence that combined treatment with cytotoxic effector cells and CRAd-CCL20-IL15 may offer alternative treatment options for tumor therapy.