Author of

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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

  • 26216

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    MA27.06 - Therapeutic Silencing of Oncogenic KRAS With a Mutant-Specific Short Interfering RNA (ID 12227)

    14:05 - 14:10  |  Author(s): Bjoern Papke
    • 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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