Sub-acute Toxicity in Non-cancerous Tissue and Immune-Related Adverse Events of a Novel Combination Therapy for Cancer

Abstract

Brain, lung, and colon tissue experience deleterious immune-related adverse events when immune-oncological agents or radiation are administered. However, there is a paucity of information regarding whether the addition of radiation to immuno-oncological regimens exacerbates the tissue inflammatory response. We used a murine model to evaluate sub-acute tissue damage and the systemic immune response in C57Bl/6 mice when administered systemic anti-programmed cell death protein 1 (αPD-1) immunotherapy alone or in combination with stereotactic fractionated 10 gray/5 X-ray radiation to normal brain, lung or colon tissue. The model indicated that combinatorial αPD-1 immunotherapy and radiation may alter normal colon cell proliferation and cerebral blood vasculature, and induce systemic thrombocytopenia, lymphopenia, immune suppression, and altered immune repertoire (including interleukin-1β). Therein our data supports close monitoring of hematological and immune-related adverse events in patients receiving combination therapy.

Glycolysis and Fatty Acid Oxidation Inhibition Improves Survival in Glioblastoma

“…Tumors treated with TMZ and/or RT and all-combined treatment showed increased DNA damage (γH2A.X; p < 0.001; Figure 9C). We have previously observed this phenomenon of prolonged γH2A.X at 28 days after RT treatment in noncancerous brain, lung, and colon tissues (24). As the patterning is not observed in unirradiated (untreated) brains, we believe that it indicates radiotoxicity to the "healthy" cells, including radiosensitive oligodendrocytes, which have shown limited regenerative capacity out to 18-month postirradiations (29).…”

“…Drugs used in this study were DCA (sodium DCA #347795; Sigma-Aldrich, St. Louis, MO, USA), TMZ (#T2577; Sigma-Aldrich St. Louis, MO, USA), and Rano (Rano dihydrochloride #R6152; Sigma-Aldrich St. Louis, MO, USA) dissolved in complete media for in vitro studies and in sterile water for in vivo studies at stock concentrations of 40, 5, and 10 mg/ml, respectively. X-ray radiation was delivered using the Small Animal Radiation Research Platform (SARRP; Xstrahl Inc., Suwanee, GA, USA) at a dose rate of 2.97 Gy/min as described earlier ( 24 ). In all experiments, the drug treatment preceded irradiation by 1 h to enable the drugs to act on their respective cellular targets.…”

“…), and Rano (50 mg/kg/day i.p.). External beam irradiation of 20 Gy/10 (i.e., 2 Gy per dose; RT) was performed using the Image-Guided SARRP (Xstrahl Inc., Suwanee, GA, USA) using a 5 × 5 mm collimator and 60° (30° to –30°) Arc beam at a dose rate of 3.71 Gy/min ( 24 ). For combination treatment groups, radiation was delivered 1-h post-drug administration.…”

“…Four-micron sections of paraffin-embedded tissues were stained with Mayer's H&E Y/erythrosine B staining, Ki67 (0.084 μg/ml; 12202S; Cell Signaling Technologies, Danvers, MA, USA), and γH2A.X (0.06 μg/ml; ab11174; Abcam, Cambridge, UK) as described earlier ( 6 , 24 ) and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis by immunohistochemical staining [ab206386; Abcam, Cambridge, UK) with Mayer's hematoxylin nuclear stain. Slides were imaged using an Aperio XT slide scanner and captured using Aperio ImageScope (Leica Biosystems, Wetzlar, Germany), and five high-power images were assessed per sample ( N = 4–6 brains per treatment group] using ImmunoRatio (Seinajoki, Finland) as described earlier ( 24 ).…”

Differential effects of radiation fractionation regimens on glioblastoma

“…In the EORTC protocol, 60 Gy is delivered in 30 fractions of 2 Gy per day over 6 weeks. We previously reported that RT of non-cancerous tissue can alter cell proliferation, blood vasculature and immunity in the sub-acute period (28 days) after conventional fractionated RT [ 21 ]. The current study assessed the biological effect of higher RT doses with fewer fractions (10 Gy/2 f per week) could reduce tumor growth, induce greater anti-tumor immunoreactivity, and minimise delayed radionecrosis compared to a conventional fractionated regimen (10 Gy/5 f per week).…”