RNA editing-based treatment for cancers associated with the KRAS G12D mutation

Mutations in KRAS are the most common genomic alterations identified in solid

tumors. Unfortunately, KRAS has long been considered to be undruggable, calling for the

development of novel technologies. Here we propose to test RNA-editing based

technology, using the Adenosine deaminase acting on RNA (ADAR) RNA editing proteins.

ADARs are endogenous enzymes that catalyze the deamination of adenosines (A) to inosines

(I), which are then read as guanosines (G) during translation. Advances made in

understanding ADAR mode of action enabled the development of site-directed RNA editing

(SDRE) technologies for its recruitment to target sites and reprogramming genetic

information. We suggest testing whether SDRE can be used to correct one of KRAS’s most

frequent mutations, the conversion of glycine at codon 12 to aspartic acid (G12D) (KRAS-

G12D). ADARs preferentially edit double-stranded RNA (dsRNA) regions, hence, to attract

ADARs to target sequences, antisense sequences (gRNA) are employed. However, no rules

are yet known for the construction of these elements, in particular for cancer. In this study

we use an experimental high throughput yeast-based screening system to identify and

optimize the sequences that enhance ADAR recruitment to KRAS-G12D, and efficient A-to-I

editing. We believe that positive results would serve as the proof of concept and lay the

foundation for the clinical application of this treatment in patients who carry the KRAS-G12D

mutation. We also expect that if successful, ADAR mediated base editing should open new

avenues for treating other patients carrying mutations amenable for ADAR editing.