GNPX 2017 Annual Report

22 Tumor free mice without mutations that lead to metastasis were injected intravenously with TUSC2 which caused a threefold up-regulation of NK cells in the peripheral blood of TUSC2 injected mice as compared with non-injected mice. CD8 T cells, which are cytotoxic T cells (CTL) for tumor killing, act as a prognostic marker of tumor regression. Increased numbers of CTL were found in the TUSC2 and TUSC2+PD1 groups as compared with that of the control group which directly correlated with the anti-tumor effect, as shown in the graph below. Lower levels of CD62L expression on T lymphocytes in TUSC2 treated mice suggests that TUSC2 regulates T cell activation. Moreover, TUSC2 induced down-regulation of regulatory T cells (Treg, CD4+CD25+). TUSC2 was shown to down-regulate checkpoint markers such as PD-1, CTLA-4, Tim-3, and LAG-3. 13-Effect of TUSC2 with Anti-PD1 on Immune Cell Populations in Peripheral Blood (Large) Preclinical Study Showing that TUSC2 Immunogene Therapy is Synergistic with Anti-PD1 in Lung Cancer Syngeneic Mouse Models Based on the prolonged responses that were observed in TUSC2 clinical trials, which suggest that TUSC2 may modulate the immune response, and on the fact that checkpoint blockade immunotherapy against PD1 and PD-L1 has yielded durable antitumor activity in a subset of NSCLC patients, MD Anderson researchers conducted a preclinical study to investigate the immune response to TUSC2 in immune cell populations and the synergistic antitumor effect of TUCS2 in combination with anti-PD1 checkpoint blockade in syngeneic mouse NSCLC models. Two Kras-mutant syngeneic mouse models were used to explore the effect of TUSC2+anti-PD1 (+/- anti-CTLA-4) on immune cells infiltration into the tumor micro-environment. Activating Kras mutations are the most common driver mutations in lung adenocarcinomas. Lung cancer with mutant Kras has a poor prognosis, is often resistant to conventional therapy, and readily becomes resistant to targeted therapies with kinase inhibitors. Studies by researchers not at MD Anderson have found that PD1 expression was highly associated with the presence of Kras mutations and that PD-L1 expression was elevated in premalignant Kras-mutant cells, suggesting that Kras mutation may affect the function of the PD1/PD-L1 immune checkpoint pathway. The first syngeneic mouse model used a murine lung carcinoma cell line CMT/167-luc with a Kras G12V mutation and a low level of TUSC2 expression, implanted subcutaneously in C57BL/6 mice. The second syngeneic mouse model optimized an aggressive experimental metastatic lung cancer model using 129SvE mice injected with SQ344 lung cancer cells, which contained KrasG12D allele. The SQ344 tumor model was found to be less sensitive to anti-PD1 single agent treatment.