Ad-CD40L mobilizes CD4 T cells for the treatment of brainstem tumors

Diffuse Midline Glioma, formerly Diffuse Intrinsic Pontine Glioma (DIPG), is the deadliest pediatric brainstem tumor with median survival of less than one year. Here, we investigated 1) whether direct delivery of adenovirus expressing CD40L (Ad-CD40L) to brainstem tumors would induce immune-mediated tumor clearance and, 2) if so, whether therapy would be associated with a manageable toxicity due to immune-mediated inflammation in the brainstem. Methods Syngeneic gliomas in the brainstems of immune competent mice were treated with Ad-CD40L and survival, toxicity and immune profiles determined. A clinically translatable vector, whose replication would be tightly restricted to tumor cells, rAd-Δ24-CD40L, was tested in human patient-derived Diffuse Midline Gliomas and immunocompetent models. Results Expression of Ad-CD40L restricted to brainstem gliomas by pre-infection induced complete rejection, associated with immune cell infiltration, of which CD4+ T cells were critical for therapy. Direct intra-tumoral injection of Ad-CD40L into established brainstem tumors improved survival and induced some complete cures but with some acute toxicity. RNA-seq analysis showed that Ad-CD40L therapy induced neuroinflammatory immune responses associated with IL-6, IL-1β and TNF-α. Therefore, to generate a vector whose replication, and transgene expression, would be tightly restricted to tumor cells, we constructed rAd-Δ24-CD40L, the backbone of which has already entered clinical trials for Diffuse Midline Glioma. Direct intra-tumoral injection of rAd-Δ24-CD40L, with systemic blockade of IL-6 and IL-1β, generated significant numbers of cures with readily manageable toxicity. Conclusions Virus-mediated delivery of CD40L has the potential to be effective in treating Diffuse Midline Gliomas without obligatory neuroinflammation-associated toxicity

Consequences of 1,3-butadiene DNA adducts – R,R-N6,N6-DHB-dA and R,S-1,N6-g-HMHP-dA – on DNA base pairing

DNA is the hereditary material in humans and almost all other organisms. Unfortunately, upon exposure to carcinogenic species and other compounds, our DNA can be damaged in a variety of ways. An example of DNA damage includes the formation of bulky nucleobase addition products (adducts), which may give rise to cancer. This poster focuses on adducts formed upon exposure to 1,3-butadiene – a human carcinogen that has been associated with an increased incidence of leukemia (cancer of the blood cells). Sources of 1,3-butadiene exposure include automobile exhaust and tobacco smoke, as well as polluted water and air at or near chemical, plastic or rubber facilities. In order to understand the consequences of DNA exposure to 1,2,3,4-diepoxybutane – a metabolite of 1,3-butadiene –  this study examines the hydrogen-bonding properties of two adenine (dA) adducts formed upon addition of a bulky moiety to the N6 position, namely the R,R-N6,N6-DHB-dA and R,S-1,N6- g-HMHP-dA adducts. Previous studies have shown that human translesion DNA polymerases hand k preferentially incorporated A, C, G or T opposite R,R-N6,N6-DHB-dA, and A, G or T opposite R,S-1,N6-g-HMHP-dA. This study seeks to explain the observed mutagenicity of these adducts and is the first step in determining the effect of these adducts on the DNA duplex. Figure 1. 1,3-butadiene adducts R,R-N6,N6-DHB-dA (left) and R,S-1,N6-g-HMHP-dA (right