Developing Tumor-Localized, Combination Immunotherapies

Building on the recent clinical successes of checkpoint inhibitor antibodies, the field of cancer immunotherapy is now focussing on combination treatment regimens to further improve efficacy benefits to patients. However, combining such systemically dosed agents is associated with a number of challenges including enhanced side effect profiles and high costs. One strategy being explored to overcome such issues is to dose the therapeutics directly into the tumor rather than systemically but many tumors will not be accessible for this type of treatment. We have developed a broadly applicable vector platform system, based on the potent chimeric oncolytic group B adenovirus enadenotucirev (EnAd), for directing the efficient local production of a combination of immunotherapeutic agents selectively within the tumor. The versatility and fidelity of the platform has been exemplified by encoding up to three separate biomolecules in the same virus, including antibodies, cytokines, chemokines and tumor-associated antigens, without altering other virus properties. A systemic clinical dosing regimen has been established for EnAd, with data directly demonstrating selective virus delivery to and protein production from colorectal and other tumor types. The advantage of this approach is that immunotherapeutics encoded in the virus can be produced locally, both in tumors that are not directly injectable and in metastases, while minimising systemic off-target effects. A candidate virus NG-345 has been designed to produce a combination of three secreted immunomodulatory agents (human IFNa, MIP1a and Flt3L) aimed at enhancing the recruitment and activation of immune cells into tumor cell nests. We have shown that NG-345 retains the full oncolytic properties (potency and selectivity) of the parental EnAd virus, with infected human tumor cells producing high levels of all three cytokine/chemokines in the culture supernatants. Functional activity of individual encoded agents has also been demonstrated using relevant cell-based assays. EnAd is highly human-tumor selective and does not replicate, produce infectious progeny or express endogenously regulated transgenes in non-human cells. In vivo evaluation of immuno-modulatory activities of armed viruses is therefore challenging and requires the application of multiple approaches that can collectively provide informative data. In particular, studies are focusing on using surrogate candidate viruses expressing murine gene homologs in human tumor xenografts in immunodeficient mice with or without a reconstituted immune system. Citation Format: Brian R. Champion, Nalini Rasiah, Sam Illingworth, Matthieu Besneux, Rochelle Lear, Darren Plumb, Prithvi Kodialbail, Alice C.N. Brown. Developing tumor-localized, combination immunotherapies. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4875.