{
  "abstract": "Background Most cancer patients experiencing clinical benefit from immune checkpoint inhibitor (CPI) therapy eventually develop acquired resistance (AR) and relapse. One AR mechanism involves transcriptional hyperactivation of genes associated with chronic IFN signaling. Analysis of preclinical AR models and human cancer transcriptomics identified the E3 ubiquitin ligase TRIM7, as a driver of the AR phenotype. TRIM7 is also upregulated in KRAS mutant and MSI-high tumors, and (1) mediates cell proliferation downstream of aberrant RTK/RAS/RAF signaling through ubiquitination and stabilization of RACO-1 and (2) modulates IFN responsiveness through ubiquitination and degradation of MAVS. Here we describe the development of small molecule inhibitors (SMI) to TRIM7 and validate it as a promising target in RTK/RAS driven cancers.Methods MST, fluorescent polarization, and mass spec determined binding specificity/affinity of >500 TRIM7 SMI. Solubility, stability, and half-life were assessed in plasma. Membrane permeability/efflux were determined using MDCK-MDR1. Potency was evaluated using target ubiquitination/stabilization/degradation, human tumor growth inhibition (TGI), transcriptional profiling, and in vivo efficacy in human xenograft models.Results TRIM7 inhibition disrupted the ubiquitination and stability of RACO-1, resulting in decreased phosphorylation of c-Jun and STAT3, and altered transcription of c-Jun/AP-1 targets. Degradation of RACO-1 resulted in significant TGI in both EGFR/KRAS wild-type and mutant tumor cell lines, and outperformed other KRAS pathway inhibitors like Sotorasib and Zoldonrasib, without selectivity to specific KRAS mutations. TRIM7 specificity was confirmed using inactive enantiomers of lead SMI, which did not induce TGI. In addition, TRIM7 inhibition reduced ubiquitination of MAVS, resulting in MAVS accumulation, and transcriptional changes in interferon responsiveness genes. In vivo, TRIM7 inhibitors as monotherapy delayed the growth of aggressive CT26/AR tumors (KRAS G12D), and human NSCLC and KRAS mutant CRC tumor xenografts. TRIM7 over-expression in NCI-H1299 lung cancer cells resulted in the downregulation of previously defined ‘good’ interferon stimulatory genes (ISGs), including IDO1, IFIT2, and ISG20, and upregulation of ‘bad’ ISGs, including STAT1, CXCL1, and OAS3. TRIM7 inhibition reversed these transcriptional patterns and downregulated genes associated with KRAS pathway activation, including RACO-1(RNF187), MAP2K2, and RASA1.Conclusions TRIM7 controls cell proliferation and IFN responsiveness downstream of RTK/RAS/RAF and was identified as a candidate mediator of CPI acquired resistance. TRIM7 inhibition reduced tumor growth in vitro and in vivo and outperformed multiple KRAS inhibitors as monotherapy. Lead TRIM7 inhibitors warrant further development to address the unmet need in cancers that evolve with various resistance mechanisms, including aberrant RTK/RAS/RAF signaling.Ethics Approval Animal studies were approved by an Institutional Animal Care and Use Committee (IACUC); and a licensed veterinarian.",
  "authors": [
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Yuhui Chen"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Marc Morra"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Haru Katu"
    },
    {
      "affiliations": [
        "R2M Pharma, Inc, San Francisco, CA, USA"
      ],
      "name": "Kevin Li"
    },
    {
      "affiliations": [
        "R2M Pharma, Inc, San Francisco, CA, USA"
      ],
      "name": "Ulhas Bhatt"
    },
    {
      "affiliations": [
        "R2M Pharma, Inc, San Francisco, CA, USA"
      ],
      "name": "Kevin Gayler"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Derek Franklin"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Grace Elliott-Fromm"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Nathan Oien"
    },
    {
      "affiliations": [
        "R2M Pharma, Inc, San Francisco, CA, USA"
      ],
      "name": "Julio Medina"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "Taylor H Schreiber"
    },
    {
      "affiliations": [
        "Shattuck Labs, Inc., Durham, NC, USA"
      ],
      "name": "George J Fromm"
    }
  ],
  "title": "1167 TRIM7 inhibition blocks RTK/RAS pathway driven tumor cell proliferation independent of mutation and restores tumor-intrinsic IFN responsiveness",
  "uid": "c51edaca-2bf9-563f-af19-a3b4e1fe3333"
}