KRAS mutations are among the most common oncogenic drivers in solid tumors, occurring in ~30% of non-small cell lung cancers (NSCLC), 40% of colorectal cancers (CRC), and >90% of pancreatic ductal adenocarcinomas (PDAC). While the development of KRAS G12C inhibitors (e.g., sotorasib, adagrasib) marked a breakthrough, resistance inevitably develops through secondary mutations or adaptive bypass mechanisms. Synthetic lethality (SL)—a strategy targeting vulnerabilities unique to KRAS-mutant cells—offers a promising approach to overcome resistance. This article explores the latest SL strategies for KRAS-resistant tumors and their therapeutic potential.
Intrinsic heterogeneity: Subclonal KRAS variants (G12D/V/R) insensitive to G12C inhibitors.
Co-mutations: STK11/LKB1, TP53, or KEAP1 loss diminishing drug efficacy.
On-target mutations: KRAS G12C→G12R/D or Y96D alterations.
Off-target adaptations:
Activation of RTK/MAPK bypass pathways (EGFR, MET, AXL).
PI3K/mTOR or RAF/MEK reactivation.
Autophagy or SWI/SNF complex dependency.
Synthetic lethality occurs when inhibition of two genes is lethal, but blocking either alone is not. For KRAS-mutant tumors, SL targets include:
Rationale: KRAS mutations induce replication stress and homologous recombination (HR) deficiency.
Preclinical evidence:
Olaparib + MEK inhibitors show synergy in KRAS-mutant CRC/PDAC.
KRAS G12D tumors are sensitive to PARP + ATR inhibitors.
Clinical trials:
NCT04171700: Olaparib + trametinib in KRAS-mutant solid tumors.
KRAS upregulates ATR/CHK1 to cope with DNA damage.
Combination strategies:
ATRi (berzosertib) + KRAS G12C inhibitors overcome resistance in NSCLC.
KRAS-mutant cells rely on glutamine metabolism.
Telaglenastat (CB-839) + KRASi induces ferroptosis in PDAC models.
Targeting GFPT1 or OGT selectively kills KRAS-driven tumors.
KRAS mutants require HSP90 for stability.
Ganetespib + trametinib shows efficacy in KRAS-mutant NSCLC.
Chloroquine + KRAS G12C inhibitors overcome resistance in CRC.
KRAS mutations increase cytosolic DNA → STING-dependent PD-L1 upregulation.
STING agonists + anti-PD1 enhance T-cell infiltration.
KRAS/TP53 co-mutations increase CDK4/6 dependency.
Palbociclib + KRASi delays progression in PDAC.
Recent genome-wide CRISPR knockout screens identified novel KRAS SL pairs:
| KRAS Mutation | Synthetic Lethal Target | Therapeutic Approach |
|---|---|---|
| G12D/V | KEAP1 | NRF2 inhibitors |
| G12C | WEE1 | Adavosertib + sotorasib |
| G12R | SHP2 | RMC-4550 (SHP2i) |
NCT05462717: Adagrasib + divarasib (SHP2i) in KRAS G12C NSCLC.
NCT04892017: Sotorasib + bevacizumab (anti-VEGF) in CRC.
NCT05252390: MRTX1133 (KRAS G12Di) + PARPi in PDAC.
Tumor heterogeneity necessitates combinatorial approaches.
Toxicity from dual pathway inhibition (e.g., DDR + MAPKi).
Biomarker development to predict SL responses.
CRISPR-Guided Personalized SL
Patient-derived organoid screens to identify optimal combinations.
Triple-Therapy Strategies
e.g., KRASi + PARPi + immunotherapy.
Novel Targets
UBE2M (neddylation pathway) and PCNA show SL potential.
Synthetic lethality represents a powerful strategy to combat KRAS resistance, leveraging the unique biology of mutant KRAS tumors. While challenges remain, the integration of CRISPR screens, targeted inhibitors, and immunotherapy is paving the way for durable responses. As clinical trials progress, SL approaches may finally unlock the long-elusive goal of curative therapies for KRAS-driven cancers.
