Upper Tract Urothelial Carcinomas (UTUC) are extremely aggressive tumors of ureter or renal pelvis. UTUC present less tumor mutational burden and low tumor immune infiltrate compared to bladder cancer. Despite this they are treated with the same protocol than bladder cancer with more than 50% of relapses justifying the need of new therapeutic options. To improve patient care, we suggest stimulating the immune system by platinum-based chemotherapies (Cisplatin-Gemcitabine (CisGem) or Carboplatin-Gemcitabine (CarboGem)) in order to potentiate the effect of an anti-PD-L1, the Durvalumab. We launched a phase II clinical trial called “iNDUCT” which studies these combinations in UTUC patients. In parallel, we conduct an in vitro project that aims to determine if chemotherapies could transform cold tumor into a hot tumor, and if so by which mechanisms? Using UTUC cell lines (UM-UC-14,UCC03,UCC17,UCC14,UCC47) we have evaluated the cytotoxicity effects of the chemotherapies combinations in 2D and 3D cell cultures. We have assessed their potential (i) to induce DNA damage using image cytometry, (ii) to induce PD-L1 expression using flow cytometry, (iii) to induce immune cell death using ELISA kits, (iv) to activate the cGAS/STING pathway using qPCR and Western-Blot, and finally (v) to attract immune cells by using heterotypic spheroids model (tumoral cells+PBMCs).Our results demonstrate that CisGem and CarboGem present synergistic effects in UTUC spheroid cultures. These treatments also induce DNA damage pathway demonstrated by an increase of γH2AX, P-ATM, P-CHK1 and P-CHK2 positive cells. We found an increase of PD-L1 membrane expression after treatment in UTUC cell lines. RNA Seq analyses indicates that the major pathways upregulated by these combinations are inflammatory pathways (TNF-α signaling via NFkB, interferon alpha response, inflammatory response, interferon gamma response). We could observe an immune cell death induction demonstrated by an increase of ATP and HMGB1 release and calreticulin translocation. We showed cGAS/STING pathway activation as evidenced by an increase of P-IRF3 and interferon stimulated genes (ISGs) expression. We demonstrated an inhibition of the ISGs induction after treatment by our chemotherapies when cells are treated with an ATM inhibitor or in UMUC-14 deleted for STING. And we finally showed that CisGem and CarboGem can increase immune infiltration in the heterotypic tumor spheroids. These results indicate that the combination of platinum salts + gemcitabine induces inflammatory pathways via a non-canonical STING pathway dependent on ATM activation in UTUC model. Furthermore, these combination induce an upregulation of PD-L1 expression and allow immune cells attraction at the tumor. All these data support that a combination CisGem or CarboGem with an anti-PD-L1 will be efficient for UTUC patients. Citation Format: Alexandra Fauvre, Nadia Vie, Mathilde Robin, Clara Taffoni, Nadine Laguette, Julien Faget, Laurent Gros, Aurélie Garcin, Celine Gongora, Nadine Houede. Platinum-based chemotherapy immunomodulatory effects and immunotherapy association in upper tract urothelial carcinomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1294.

YAP and TAZ, the Hippo pathway terminal transcriptional activators, are frequently upregulated in cancers. In tumor cells, they have been mainly associated with increased tumorigenesis controlling different aspects from cell cycle regulation, stemness, or resistance to chemotherapies. In fewer cases, they have also been shown to oppose cancer progression, including by promoting cell death through the action of the P73/YAP transcriptional complex, in particular after chemotherapeutic drug exposure. We show here that oxaliplatin treatment on colorectal cancer HCT116 cells led to a dramatic core Hippo pathway down-regulation and nuclear accumulation of TAZ. We further show that TAZ was required for the increased sensitivity of HCT116 cells to oxaliplatin, an effect that appeared independent of P73, but which required the nuclear relocalization of TAZ. Our results support thus an early action of TAZ to sensitize cells to oxaliplatin, consistent with a model in which nuclear TAZ in the context of DNA damage and P53 activity pushes cells towards apoptosis.

3091 Background: Using an in vitro dose matrix approach, we previously showed in multiple colorectal cancer cell lines a striking cytotoxic synergism between oxaliplatin at very low concentrations and the ATR inhibitor VE-822. We confirmed this finding in vivo, and, surprisingly, in this setting the oxaliplatin-induced cell addiction to VE-822 persists over several days after oxaliplatin elimination. We tried to elucidate the molecular mechanism of the latter phenomenon. Methods: We evaluated by RNAseq the gene expression changes induced in vitro by low-dose oxaliplatin in the colorectal cancer cell line HCT-116 after 24 and 48 hours of treatment. In order to untangle the functional significance of the adaptive response to oxaliplatin, we performed on the RNAseq data an extensive gene set enrichment analysis (GSEA) using gene set from all Molecular Signature Database v7.4 collections with the exception of C7. For ontology-based gene set collections, we clusterized the enriched gene sets using the semantic similarity methodology in order to increase the readability of global functional response. Results: Extensive GSEA showed that after 24 hours of oxaliplatin treatment cancer cells upregulate several gene sets involved in aspecific responses to cellular stress or to various type of extracellular stimulations, including other organisms, oxygen-containing compounds, abiotic stimuli and hypoxia. In addition, several gene sets involved in proteolysis and autophagy are upregulated, suggesting a rewiring of cell machinery. After 48 hours of oxaliplatin treatment, we observed the activation of ribosome function, mitochondrial assembly and synthesis of aminoacids and ribonucleosides. Finally, a widespread negative enrichment of gene sets involved in DNA repair-related was detected both at 24 and at 48 hours, with a far greater negative enrichment at 48 hours, which suggest a commitment of cancer cell to a major limitation of DNA repairing capability lasting several days following a DNA damaging insult. Analysis of leading edge genes from the DNA repair gene sets showed a profound repression both at 24 and 48 hours of the transcripts of BRCA1, BRCA2, ATM, CHK1, WEE1, BARD1, BRIP1, NEHJ1, RAD51, XRCC2, CLSPN, GEN1, DNA2, EXO1, TOPBP1, POLE, RMI1. Interestingly, ATR mRNA was minimally repressed both at 24 and at 48 hours, which could explain the long-standing in vivo dependence of cancer cell to ATR after a brief oxaliplatin exposure. Conclusions: Extensive GSEA was able to elucidate the molecular mechanism underlying synergistic interaction between oxaliplatin and VE-822. The impact of profiling cancer cell adaptive responses by extensive GSEA should be further evaluated in the setting of rational development of drug combinations.