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Published on: December 1, 2016
RAF1 as a standalone therapeutic target in KRAS-driven lung adenocarcinoma: No added efficacy from co-targeting ARAF,
Laura de-la-Puente-Ovejero1,2, Ana Fernández-Rodríguez1,2, Sarah Francoz1
1Experimental Oncology Group, Tumor Biology Programme, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.
Background/Objectives:
KRAS-mutant lung adenocarcinoma remains without effective targeted therapies for most patients, particularly those with non-G12C alleles or resistance to KRASG12C inhibitors. RAF1 is essential for KRAS-driven tumor maintenance through kinase-independent survival functions, making it an attractive candidate for targeted protein degradation. However, the therapeutic impact and safety of co-targeting RAF1 with related kinases remain unclear.
Methods:
We used dual-recombinase genetically engineered mouse models of Kras+/G12V;Trp53-/- lung cancer to evaluate the effects of Raf1 ablation alone or in combination with Araf, Egfr, or Ddr1. Lung tumors were initiated by intranasal Ad5-CMV-FLPo delivery and allowed to reach CT-detectable size before inducing systemic gene deletion via tamoxifen-activated CreERT2. Tumor burden was monitored by longitudinal CT imaging and classified using RECIST-like criteria. Toxicity was assessed by body weight monitoring, histopathology of major organs, and survival analysis.
Results:
Raf1 deletion induced robust tumor regression within two months, in more than 60% of lesions. Araf ablation alone or combined with Raf1 did not affect tumor initiation, progression, or regression rates. Similarly, neither genetic nor pharmacological EGFR inhibition (afatinib) improved responses to Raf1 ablation. Ddr1 co-deletion also failed to enhance therapeutic efficacy and slightly reduced response rates. None of the dual-targeting strategies increased systemic toxicity.
Conclusions:
RAF1 is a key, non-redundant vulnerability in KRAS-driven lung adenocarcinoma. Co-targeting ARAF, EGFR, or DDR1 provides no additional therapeutic benefit in established disease. The absence of adverse effects from ARAF co-deletion suggests that RAF1 degraders with partial cross-activity towards ARAF are likely to be safe. These findings provide a strong preclinical rationale for developing RAF1-targeted degradation as a monotherapy for these malignancies.
Insights
Targeting RAF1 shows promise for KRAS-mutant lung cancer, as its ablation effectively shrinks tumors. Co-targeting other kinases like ARAF, EGFR, or DDR1 did not improve outcomes or safety in preclinical models.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- KRAS-mutant lung adenocarcinoma lacks effective targeted therapies for many patients.
- RAF1 plays a crucial role in KRAS-driven tumor maintenance via kinase-independent survival pathways.
- The therapeutic potential and safety of simultaneously targeting RAF1 with related kinases are not well understood.
Purpose of the Study:
- To investigate the therapeutic efficacy and safety of RAF1 ablation, alone and in combination with ARAF, EGFR, or DDR1, in Kras-mutant lung adenocarcinoma.
- To assess the impact of these dual-targeting strategies on tumor regression and systemic toxicity in a preclinical mouse model.
Main Methods:
- Utilized dual-recombinase genetically engineered mouse models of Kras+/G12V;Trp53-/- lung cancer.
- Induced lung tumors and subsequently deleted Raf1, alone or with Araf, Egfr, or Ddr1, using tamoxifen-inducible CreERT2.
- Monitored tumor burden via longitudinal CT imaging and assessed toxicity through body weight, histopathology, and survival analysis.
Main Results:
- RAF1 deletion led to significant tumor regression in over 60% of lesions within two months.
- Co-deletion of ARAF, or combined genetic/pharmacological inhibition of EGFR, did not enhance RAF1 ablation efficacy.
- DDR1 co-deletion showed no benefit and slightly reduced response rates; none of the dual-targeting strategies increased systemic toxicity.
Conclusions:
- RAF1 represents a critical, non-redundant therapeutic vulnerability in KRAS-driven lung adenocarcinoma.
- Co-targeting ARAF, EGFR, or DDR1 offers no additional benefit in established disease.
- RAF1-targeted protein degradation is a promising monotherapy strategy for these cancers, with potential safety demonstrated by ARAF co-deletion studies.
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