Introduction and Context
For decades, mutations in the KRAS gene were considered ‘undruggable,’ representing a significant hurdle in the treatment of non-small cell lung cancer (NSCLC). However, the landscape of precision oncology has shifted dramatically. While the KRAS G12C mutation has recently seen the approval of targeted inhibitors like sotorasib and adagrasib, other variants—such as KRAS G12V—remain less understood. KRAS G12V is one of the most frequent KRAS mutations, yet its specific clinical behavior and molecular dependencies have only recently been clarified through large-scale retrospective analyses.
The need for mutation-specific guidelines arises from the realization that KRAS is not a monolithic entity. Different amino acid substitutions at codon 12 lead to distinct biochemical properties and, consequently, different clinical outcomes. As we move toward a ‘divide and conquer’ strategy in lung cancer therapy, understanding the molecular and clinical characteristics of KRAS G12V is essential for optimizing patient care, particularly regarding the use of immune checkpoint blockade (ICB).
New Guideline Highlights
Recent data published in Clinical Cancer Research (John F, et al., 2025) provides a comprehensive framework for understanding KRAS G12V-mutated NSCLC. The core takeaways for clinicians emphasize that this mutation is highly associated with heavy tobacco use and high co-mutation rates in genes that modulate the tumor microenvironment. Most importantly, the research highlights a significant therapeutic advantage for immunotherapy in this subset.
- Smoking Association: Nearly 95% of patients with KRAS G12V mutations are current or former smokers, often with high tobacco exposure (median 40 pack-years).
- Immunotherapy Efficacy: Patients with G12V mutations show improved progression-free and overall survival when treated with ICB-based regimens compared to chemotherapy alone.
- Molecular Complexity: Frequent co-mutations in TP53, STK11, and KEAP1 define the G12V landscape, influencing the response to therapy.
Molecular Landscape and Key Changes
Historically, KRAS mutations were grouped together. The current expert consensus, however, advocates for individual assessment of the specific mutation variant. The co-mutation profile of G12V is particularly notable for its high frequency of STK11 and KEAP1 mutations—markers often associated with resistance to immunotherapy in other contexts. Yet, in the G12V cohort, the high smoking-induced mutational burden appears to counterbalance some of these negative prognostic factors.
| Feature | KRAS G12V Observations | Comparison to General NSCLC |
|---|---|---|
| TP53 Co-mutation | 40.2% | Highly frequent, similar to G12C |
| STK11 Co-mutation | 30.2% | Higher than in non-mutated KRAS |
| KEAP1 Co-mutation | 29.3% | Significantly elevated in G12V smokers |
| PD-L1 Expression | High (especially in heavy smokers) | Positive correlation with pack-years |
Topic-by-Topic Recommendations
1. Diagnostic Criteria and Molecular Testing
Clinicians should ensure that NGS (Next-Generation Sequencing) panels include not only the specific KRAS variant but also common co-mutations like STK11, KEAP1, and TP53. Identification of KRAS G12V should trigger an assessment of PD-L1 expression levels, as these are critical for determining the first-line treatment strategy. Evidence suggests that heavy smokers with G12V have a higher likelihood of high PD-L1 (TPS ≥50%).
2. First-Line Treatment Strategies
Based on the latest retrospective survival data, immune checkpoint blockade (ICB)—either as monotherapy (for high PD-L1) or in combination with chemotherapy—should be prioritized over chemotherapy alone. The study by John F et al. demonstrated that in patients with advanced G12V-mutated disease, ICB-based treatment achieved a median real-world overall survival (rwOS) of 30 months in those with PD-L1 TPS ≥50%.
3. Addressing Heavy Smokers
A key finding is the distinct profile of heavy smokers (≥30 pack-years) within the G12V population. These patients exhibit higher PD-L1 expression and more frequent TP53 and KEAP1 mutations. Despite the presence of KEAP1—a known resistance marker—the ‘inflamed’ phenotype associated with high tobacco exposure seems to render these tumors susceptible to ICB.
4. T-Cell Infiltration and the Microenvironment
G12V mutations show a trend toward higher CD8+ T-cell infiltration compared to non-G12V KRAS subtypes. This ‘hot’ tumor microenvironment supports the use of dual checkpoint blockade (e.g., PD-1 plus CTLA-4 inhibitors) in future clinical trials, particularly for patients who may not respond optimally to monotherapy.
Expert Commentary and Insights
Experts in thoracic oncology suggest that the G12V variant represents a unique therapeutic opportunity. Dr. Michael Scheffler and colleagues noted that while STK11 and KEAP1 mutations are usually ‘cold’ markers, their coexistence with a heavy smoking history in G12V patients creates a complex immunological tug-of-war. The consensus is that the high Tumor Mutational Burden (TMB) typically found in heavy smokers provides enough neoantigens to trigger an immune response, even when suppressive mutations are present.
One area of ongoing controversy is the role of targeted G12V inhibitors. Unlike G12C, the G12V mutation does not have an approved covalent inhibitor yet. However, several allele-specific inhibitors and ‘pan-KRAS’ (multi-RAS) inhibitors are currently in Phase I/II clinical trials. Experts recommend that patients with G12V be prioritized for enrollment in these trials if they progress on standard-of-care immunotherapy.
Patient Vignette: Applying the Evidence
Robert, a 62-year-old male with a 45-pack-year smoking history, was diagnosed with Stage IV adenocarcinoma of the lung. Molecular testing revealed a KRAS G12V mutation along with a TP53 co-mutation. His PD-L1 TPS was 55%. Following the latest findings, Robert’s oncology team opted for pembrolizumab (ICB) monotherapy rather than a chemotherapy-first approach. At his 12-month follow-up, Robert showed a sustained partial response with minimal toxicity, echoing the 30-month median survival seen in recent studies for this specific molecular profile.
Practical Implications
The transition to variant-specific care in KRAS NSCLC requires a multidisciplinary effort. Pathologists must provide detailed molecular reports, and oncologists must interpret these results through the lens of smoking history and co-mutation status. For the G12V patient, the clinical ‘win’ is the clear efficacy of immunotherapy, which provides a durable treatment option that was previously unrecognized in the broader ‘KRAS-mutated’ category. As research continues, the integration of G12V-specific inhibitors will likely further refine this landscape, potentially moving toward triple-combination therapies (ICB + Chemo + Targeted) to overcome resistance mediated by STK11 or KEAP1.
References
- John F, Ruge L, Verheyen M, et al. Molecular and clinical characteristics of patients with non-small cell lung cancer (NSCLC) harboring KRAS G12V mutations. Clin Cancer Res. 2025 Dec 19. doi: 10.1158/1078-0432.CCR-25-2581.
- Skoulidis F, Heymach JV. Co-mutations and KRAS-mutant non-small-cell lung cancer. Lancet Oncol. 2019;20(6):e305-e315.
- Riely GJ, et al. Five-Year Outcomes With Pembrolizumab in Patients With Advanced Non-Small-Cell Lung Cancer: KEYNOTE-001. J Clin Oncol. 2019;37(28):2518-2527.
- Arbour KC, et al. Effects of STK11 and KEAP1 Mutations on Response to Immune Checkpoint Blockade in Lung Adenocarcinoma. JAMA Oncol. 2018;4(9):1194-1200.
