[Immunomodulation in the tumor microenvironment: Therapeutic potential of combined inhibition of tumor hypoxia and PD-1/ PD-L1]. / Immunmoduláció a tumor mikrokörnyezetében: a tumorhipoxia és a PD-1/PD-L1 együttes gátlásának terápiás lehetoségei.

Tumor hypoxia plays an important role in controlling tumor progression through signaling pathways related to the transcription factor HIF-1. In addition to enhancing migration, promoting angiogenesis and regulating metabolism, the hypoxic environment also affects immune function. In this hypoxic microenvironment an immunosuppressive milieu is established, where HIF-1 upregulates the expression of PD-L1, a key regulator of the immune response. We have found that elevated expression of PD-L1 correlates with increased HIF-1 levels in cancer cell lines and clinical samples. Thus, the co-inhibition of HIF-1 and PD-1/PD-L1 offers promising therapeutic possibilities. In this review we have examined the limitations of HIF-1 and PD-1/PD-L1 inhibition as monotherapy, explored their combined benefits and evaluated the feasibility of targeting PD-L1 with HIF-1 inhibitors.

Farnesyl-transferase inhibitors show synergistic anticancer effects in combination with novel KRAS-G12C inhibitors.

BACKGROUND: Inhibition of mutant KRAS challenged cancer research for decades. Recently, allele-specific inhibitors were approved for the treatment of KRAS-G12C mutant lung cancer. However, de novo and acquired resistance limit their efficacy and several combinations are in clinical development. Our study shows the potential of combining G12C inhibitors with farnesyl-transferase inhibitors. METHODS: Combinations of clinically approved farnesyl-transferase inhibitors and KRAS G12C inhibitors are tested on human lung, colorectal and pancreatic adenocarcinoma cells in vitro in 2D, 3D and subcutaneous xenograft models of lung adenocarcinoma. Treatment effects on migration, proliferation, apoptosis, farnesylation and RAS signaling were measured by histopathological analyses, videomicroscopy, cell cycle analyses, immunoblot, immunofluorescence and RAS pulldown. RESULTS: Combination of tipifarnib with sotorasib shows synergistic inhibitory effects on lung adenocarcinoma cells in vitro in 2D and 3D. Mechanistically, we present antiproliferative effect of the combination and interference with compensatory HRAS activation and RHEB and lamin farnesylation. Enhanced efficacy of sotorasib in combination with tipifarnib is recapitulated in the subcutaneous xenograft model of lung adenocarcinoma. Finally, combination of additional KRAS G1C and farnesyl-transferase inhibitors also shows synergism in lung, colorectal and pancreatic adenocarcinoma cellular models. DISCUSSION: Our findings warrant the clinical exploration of KRAS-G12C inhibitors in combination with farnesyl-transferase inhibitors.