Recombinant Newcastle disease virus immunotherapy drives oncolytic effects and durable systemic antitumor immunity

A recombinant Newcastle Disease Virus (NDV), encoding either a human (NDVhuGM-CSF, MEDI5395) or murine (NDVmuGM-CSF) GM-CSF transgene, combined broad oncolytic activity with ability to significantly modulate genes related to immune functionality in human tumor cells. Replication in murine tumor lines was significantly diminished relative to human tumor cells. Nonetheless, intratumoral injection of NDVmuGM-CSF conferred antitumor effects in three syngeneic models in vivo; with efficacy further augmented by concomitant treatment with anti-PD-1/L-1 or T cell agonists. Ex vivo immune-profiling, including TCRseq, revealed profound immune-contexture changes; consistent with priming and potentiation of adaptive immunity and tumor-microenvironment (TME) re-programming towards an immune-permissive state. CRISPR modifications rendered CT26 significantly more permissive to NDV replication, and in this setting NDVmuGM-CSF confers immune-mediated¬¬¬¬¬¬ effects in the non-injected tumor in vivo. Taken together the data supports the thesis that MEDI5395 primes and augments cell mediated antitumor immunity and has significant utility as a combination partner with other immunomodulatory cancer treatments

The MEK inhibitor selumetinib complements CTLA-4 blockade by reprogramming the tumor immune microenvironment

Abstract Background T-cell checkpoint blockade and MEK inhibitor combinations are under clinical investigation. Despite progress elucidating the immuno-modulatory effects of MEK inhibitors as standalone therapies, the impact of MEK inhibition on the activity of T-cell checkpoint inhibitors remains incompletely understood. Here we sought to characterize the combined effects of MEK inhibition and anti-CTLA-4 mAb (anti-CTLA-4) therapy, examining effects on both T-cells and tumor microenvironment (TME). Methods In mice, the effects of MEK inhibition, via selumetinib, and anti-CTLA-4 on immune responses to keyhole limpet haemocyanin (KLH) immunization were monitored using ex vivo functional assays with splenocytes. In a KRAS-mutant CT26 mouse colorectal cancer model, the impact on the tumor microenvironment (TME) and the spleen were evaluated by flow cytometry. The TME was further examined by gene expression and immunohistochemical analyses. The combination and sequencing of selumetinib and anti-CTLA-4 were also evaluated in efficacy studies using the CT26 mouse syngeneic model. Results Anti-CTLA-4 enhanced the generation of KLH specific immunity following KLH immunization in vivo; selumetinib was found to reduce, but did not prevent, this enhancement of immune response by anti-CTLA-4 in vivo. In the CT26 mouse model, anti-CTLA-4 treatment led to higher expression levels of the immunosuppressive mediators, Cox-2 and Arg1 in the TME. Combination of anti-CTLA-4 with selumetinib negated this up-regulation of Cox-2 and Arg1, reduced the frequency of CD11+ Ly6G+ myeloid cells, and led to the accumulation of differentiating monocytes at the Ly6C+ MHC+ intermediate state in the tumor. We also report that MEK inhibition had limited impact on anti-CTLA-4-mediated increases in T-cell infiltration and T-cell activation in CT26 tumors. Finally, we show that pre-treatment, but not concurrent treatment, with selumetinib enhanced the anti-tumor activity of anti-CTLA-4 in the CT26 model. Conclusion These data provide evidence that MEK inhibition can lead to changes in myeloid cells and immunosuppressive factors in the tumor, thus potentially conditioning the TME to facilitate improved response to anti-CTLA-4 treatment. In summary, the use of MEK inhibitors to alter the TME as an approach to enhance the activities of immune checkpoint inhibitors warrants further investigation in clinical trials

Abstract 4186: syngenomic fingerprint: the biomic characterization of the mouse syngeneic tumor models

The pre-clinical assessment of immuno-oncology (IO) therapies can be enabled by the use of murine syngeneic tumors established in immuno-competent mice. With the aims of selecting relevant models and of minimizing animal experimentation by reducing the number of models tested, the full characterisation of syngeneic models at the transcriptomic and genomic level is a key objective for pre-clinical scientists. Model characterisation includes global aCGH, exon array analysis and FACS profiling alongside exome sequencing. The model data is undergoing hypothesis free and driven analyses which are already generating valuable insights. Comparison of in vivo tumor samples with their in vitro equivalents has highlighted enrichment for a number of immune pathways; as has the comparison of different tumor lines. The genomic, transcriptomic and ‘proteomic’ model data are being integrated to give a functional output which will act as a ‘Syngenomic Fingerprint’ for each model. The resulting Syngenomic fingerprints will help pre-clinical scientists to refine their in vivo plans through an improved understanding of the limits and advantages as well as the clinical relevance of some of our preclinical models. It is also supporting the targeted modification of models to better match specific human cancer types