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Chad Victor Pecot



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    MA27 - Novel Drugs and PDX Models (ID 931)

    • Event: WCLC 2018
    • Type: Mini Oral Abstract Session
    • Track: Targeted Therapy
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/26/2018, 13:30 - 15:00, Room 206 BD
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      MA27.06 - Therapeutic Silencing of Oncogenic KRAS With a Mutant-Specific Short Interfering RNA (ID 12227)

      14:05 - 14:10  |  Presenting Author(s): Chad Victor Pecot

      • Abstract
      • Presentation
      • Slides

      Background

      Oncogenic mutations in RASgenes are well established drivers of cancer. In particular, lung, pancreatic and colorectal cancers carry high rates of oncogenic mutations in KRAS. Promising preclinical strategies with RNA interference (RNAi) have been developed to target oncogenic RAS function, yet a clinically effective anti-RAS therapy remains to be achieved. While genetic knock-down of mutant KRASwith RNAi is one promising approach, current methods are not selective and also decrease normal RAS, raising concerns about potential normal tissue toxicity.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      We took a novel in silico approach to develop a library of siRNAs that are theoretically capble of silencing mutant KRAS sequences yet spare the wild-type sequence. We utilized a 3T3 model system to test our library of siRNAS against various human KRAS G12 and G13 mutations compared with the wild-type sequence. Dose titrations were performed to assess the unique affinity of our lead candidate for mutant v. WT. Using a KRAS mutant orthotopic lung model, we assessed in vivo silencing and therapeutic effects following delivery of our lead candidate when packaged into a nanoliposome.

      4c3880bb027f159e801041b1021e88e8 Result

      Here we describe a custom designed short interfering RNA (siRNA) oligonucleotide (KRAS-m) that displays a higher affinity for the most frequent subsets of oncogenic KRASmRNAs than for wild-type KRASmRNA. Using 3T3 cells stably expressing wild-type or various KRAS mutations, we observed that KRAS-m preferentially suppressed expression of G12C, G12D, G12V and G13D missense mutations compared to wild-type KRAS. Additionally, KRAS-m impaired proliferation of lung cancer cells in 2D as well as 3D spheroids embedded in extracellular matrix. In order to optimize in vivo stability and minimize toxicity, a 2’O-methylation strategy was utilized and several equipotent modifications were found. To overcome future clinical limitations of delivering siRNA to tumors, we evaluated a lipid nanoparticle platform (LNP) clinically-proved to be safe and highly efficient at delivering systemic RNAi. Biodistribution studies in a syngeneic, orthotopic metastasis model of KRAS (G12D) lung adenocarcinoma revealed substantial uptake of LNP-siRNAs in lung tumors and metastasis. Time-kinetic studies in this model revealed a single delivery of LNP-KRAS-m siRNA significantly silenced KRAS protein expression in tumors for at least 3 days. Compared with LNP-control siRNAs, following two deliveries of LNP-KRAS-m siRNAs model led to significant reductions in disease burden.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Taken together, our data indicate a novel strategy to target oncogenic KRAS-driven lung tumors using a mutant-specific siRNA capable of targeting many of the most common KRAS mutations.

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    P1.05 - Interventional Diagnostics/Pulmonology (Not CME Accredited Session) (ID 937)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/24/2018, 16:45 - 18:00, Exhibit Hall
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      P1.05-01 - Incidence and Clinical Relevance of NSCLC Lymph Node Micro-Metastasis Detected by Staging EBUS-TBNA (ID 13829)

      16:45 - 18:00  |  Author(s): Chad Victor Pecot

      • Abstract

      Background

      Appropriate staging of non-small cell lung cancer (NSCLC) patients is crucial to provide accurate prognostic information and select appropriate treatment. Several publications have reported an approximate 20% incidence of occult micro-metastasis (MM) in surgically resected lymph nodes (LN) pathologically interpreted as negative by hematoxylin and eosin staining (H&E). Detection of MM was associated with worsened survival. The majority of NSCLC lymph node staging is now conducted using endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA). The purpose of this study is to determine the frequency of detection of occult MM in EBUS-TBNA specimens and to evaluate the impact of the presence of MM on progression-free and overall survival.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      All patients undergoing EBUS-TBNA for NSCLC lymph node staging at our institution between September 2013 and October 2017 were eligible for inclusion. Patients were identified using provider-maintained case lists, operating or procedure room electronic schedules, and tumor board patient presentations. Patients were excluded if a definitive diagnosis of NSCLC was not obtained within 3 months of the EBUS-TBNA examination or if distant metastatic disease was present at the time of diagnosis. Patient cell blocks from the EBUS-TBNA procedure were evaluated by a cytopathologist using H&E staining according to standard guidelines. Patients with N2 or N3 disease on routine cytopathology examination were excluded. Cell blocks from the included patients were sectioned into five 5 mm sections spaced at least 10 mm apart and immunohistochemistry for pan-cytokeratin was performed. The resulting slides were then reviewed for evidence of MM by a blinded cytopathologist.

      4c3880bb027f159e801041b1021e88e8 Result

      Of 887 patients screened, 44 patients were identified fitting inclusion criteria with sufficient additional tissue for testing. The mean age and smoking history were 68 ± 10 years and 45 pack-year history, respectively. The patients were majority male (61%) and Caucasian (75%). Fifty-two percent of patients were stage 1 at the time of diagnosis, 34% were stage 2, and 14% were stage 3a. Three patients (6.8%) were found to have pan-cytokeratin positive MMs. All 3 MMs detected were at N2 LN stations. The presence of MMs was associated with significantly decreased progression-free (median 210 vs. 1293 days, p=0.0099) and overall survival (median 238 vs. 1120 days, p=0.0357).

      8eea62084ca7e541d918e823422bd82e Conclusion

      LN micro-metastases can be detected during EBUS-TBNA staging examinations and are associated with poor clinical outcomes. If prospectively confirmed in a larger study, these results have significant implications for EBUS-TBNA specimen analyses and the current NSCLC staging paradigm.

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    P2.03 - Biology (Not CME Accredited Session) (ID 952)

    • Event: WCLC 2018
    • Type: Poster Viewing in the Exhibit Hall
    • Track:
    • Presentations: 1
    • Moderators:
    • Coordinates: 9/25/2018, 16:45 - 18:00, Exhibit Hall
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      P2.03-20 - Factor XIIIA-Expressing Inflammatory Monocytes Promote Lung Squamous Cancer through Fibrin Cross-Linking (ID 13585)

      16:45 - 18:00  |  Presenting Author(s): Chad Victor Pecot

      • Abstract

      Background

      Lung cancer is the leading cause of cancer-related deaths worldwide, and lung squamous carcinomas (LUSC) represent about 30% of cases. Molecular aberrations in lung adenocarcinomas have allowed for effective targeted treatments, but corresponding therapeutic advances in LUSC have not materialized. However, immune checkpoint inhibitors in sub-populations of LUSC patients have led to exciting responses.

      a9ded1e5ce5d75814730bb4caaf49419 Method

      See results

      4c3880bb027f159e801041b1021e88e8 Result

      Using computational analyses of The Cancer Genome Atlas(TCGA) dataset, we identified a subset of LUSC tumors characterized by dense infiltration of inflammatory monocytes (IMs) and poor survival. Multiplex immunohistochemistry for CD14/CCR2/pan-cytokeratin revealed that dual-positive CD14+/CCR2+ cells predominately reside in the stromal LUSC compartment and not cancer cell islets. Using immunogenomics, we found that amongst 9 immune subsets expressing CD14, IMs had the strongest relationship with CD14 expression and poor LUSC survival. With novel, immunocompetent metastasis models, we demonstrated that tumor cell derived CCL2-mediated recruitment of IMs is driven by TNFa-mediated activation of the NFkB pathway. Furthermore, tumor production of CCL2 isnecessary and sufficient for LUSC metastasis. Pharmacologic inhibition of IM recruitment with a potent CCR2 inhibitor (PF-04136309) had substantial anti-metastatic effects, which was not due to inhibition of tumor-associated macrophages (TAMs) but rather by blockade of IMs in the blood and tumor microenvironment. Notably, in contrast to TAMs, we show that IMs express high levels of Factor XIIIA (FXIIIA). We demonstrate that FXIIIA is packaged into podosome-like structures in IMs, and when in contact with fibrin the IMs are capable of rapidly creating fibrin cross-linkages. We show that FXIIIA-mediated IM fibrin cross-linking creates a scaffold for LUSC cell invasion, migration and metastases. Consist with this observation, we found clinical LUSC samples containing extensive cross-linked fibrin in the microenvironment correlated with poor relapse-free survival.

      8eea62084ca7e541d918e823422bd82e Conclusion

      Given the rapidly evolving landscape of precision immune-oncology, these findings identify IMs as a novel context-specific vulnerability of LUSC and provide an important insight into the mechanisms through which this immune cell type determines a poor prognosis.

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