Novel strategies to increase the therapeutic efficacy of chemotherapy and immunotherapy in non-small cell lung cancer

Resumen

Lung cancer is the most lethal type of cancer, since most cases are diagnosed at late stage, when treatment options are not usually curative. Despite the therapeutic and diagnostic advances made in the last decades, involving targeted therapies and immunotherapy-based regimes, the 5-year survival rate is still very low: around 19%. The principal limiting factor to achieve cures in cancer is drug resistance. Although drug combinations have been the gold-standard treatment for decades and new combinatorial strategies have been implemented overtime, eventual resistance occurs. In this clinical context, it seems clear that there is a need for the identification of novel cancer cell vulnerabilities in non-small cell lung cancer (NSCLC) that allow us to find out the best combination strategies resulting in tumor regression. To achieve this goal, we designed three different approaches to identify novel combinations in NSCLC models. The first strategy aimed to study the role of the serine protease TMPRSS4, both as prognostic biomarker in early stage NSCLC and as sensitizer to chemotherapy. We validated in a large cohort of patients that high TMPRSS4 expression was an independent prognostic factor in stage IA NSCLC. Besides, using genetic silencing strategies we found that TMPRSS4 loss sensitizes NSCLC cells to chemotherapy both in vitro and in vivo by impairing the cell proliferation machinery. The second approach consisted of targeting NSCLC cells with the dual G9a/DNMT1 inhibitor CM-272. G9a and DNMT1 are two epigenetic enzymes coexpressed in NSCLC. We observed that high levels of these proteins are associated with poor prognosis. In this context, CM-272 was an effective treatment in monotherapy in NSCLC models. Moreover, combination of CM-272 with either chemotherapy, targeted therapy or other epigenetic drugs, was highly synergistic for most cells teste. A very significant inhibition in tumor growth was obtained in vivo when combining CM-272 and cisplatin. Interestingly, we found that CM-272 cytotoxic effect was partially mediated by the re-expression of AOX1 and SCARA5 tumor suppressor genes. The third strategy was designed to provide new research tools to study the phenomenon of immunotherapy resistance in NSCLC, and to explore alternative treatments to this clinical problem. In this context, we generated syngeneic mouse models resistant to anti-PD-1 due to mutations in the tumor suppressor PTEN or mutations in the MHC-I component B2M. PTEN mutations, in a murine model of squamous cell carcinoma led to the acquisition of cancer stem cell and epithelial to mesenchymal transition features, which is likely to contribute to tumor malignancy and immune evasion. In addition, PTEN mutant models were characterized by release of immunosuppressive cytokines and increased number of T regulatory cells, which might explain this resistant phenotype. Regarding B2M loss, we have generated three different lung adenocarcinoma mouse models with B2M mutations that are resistant to anti-PD-1. Moreover, we showed that alternative treatment with C5a/C5aR inhibitors is therapeutically effective in this context. All together these three strategies offer novel combinatorial strategies that could improve NSCLC treatment.