The clinical and genomic characteristics of KRAS G12D mutated cancers.

Abstract

e15151 Background: KRAS mutations are relatively common in solid tumors. It is once considered to be “non-druggable” due to its high affinity to GTP/GDP and lack of other binding sites. Recently, irreversible inhibitors targeting specific KRAS mutations have been developed. We aimed to investigate the correlation of clinical and genomic factors with KRAS G12D mutation in pancreatic cancer (PC), colorectal cancer (CRC) and non-small-cell lung cancer (NSCLC). Methods: We retrospectively reviewed the clinical and genomic data of patients with PC (n = 300), CRC (n = 300), and NSCLC (n = 1800) who provided tumor tissues and matched peripheral blood samples (served as control to eliminate germline variants) for targeted sequencing of 450 cancer-related genes. Experiments were carried out in OrigiMed’s laboratory following the CAP/CLIA standards. Tumor mutation burden (TMB)-high was defined as TMB > 10 muts/Mb. Results: The prevalence of KRAS G12D mutation in PC, CRC and NSCLC was 38.3% (115/300), 15.0% (45/300) and 2.0% (36/1800), respectively. In PC and CRC, G12D was the major type of KRAS mutations, accounting for 44.9% (115/256) and 30.8% (45/146) of all the KRAS mutations, respectively. In contrast, G12C was the most common KRAS mutation in NSCLC (35.9% [79/220]), followed by G12D (16.4% [36/220]). Patients were divided into three groups according to the KRAS mutation status: the G12D (mutated in KRAS G12D), non-G12D (mutated in KRAS, but not G12D), and wild-type (WT; no KRAS mutation) groups. Clinical features including age, sex and disease stage were not associated with the KRAS grouping in PC and CRC. However, the KRAS grouping was significantly correlated with sex in NSCLC (Female vs Male: 1.9% vs 2.1% in G12D, 4.4% vs 13.9% in non-G12D, 93.7% vs 84.1% in WT, P < 0.001). In PC, KRAS G12D and BRAF mutations were mutually exclusive (P < 0.01), while in CRC, KRAS G12D mutation was found to be co-occurring with PIK3CA mutation (P < 0.05). For NSCLC, KRAS G12D mutation was mutually exclusive with EGFR mutation (P < 0.01) and co-occurred with STK11 mutation (P < 0.05). TMB was comparable between the KRAS grouping in PC and CRC. In contrast, TMB was significantly higher in the non-G12D group (median 11.7 [range 0.7-89.8] muts/Mb) compared to the G12D (median 6.9 [range 0-30.9] muts/Mb; P < 0.001) and WT (median 4.6 [range 0-215.2] muts/Mb; P < 0.001) groups in NSCLC. A higher proportion of TMB-high was also observed in the non-G12D group (58.5%) compared to the G12D (22.2%) and WT (22.6%) groups in NSCLC. Conclusions: Patients with KRAS G12D mutation possessed unique clinical and genomic characteristics. It was more prevalent in PC and CRC and was correlated with sex in NSCLC. KRAS G12D mutation co-occurred with STK11 mutation and showed a relatively low TMB value in NSCLC, suggesting that immunotherapy might be ineffective. While KRAS non-G12D mutated NSCLC patients may be favorable to ICI. Our results provide insights into the precision medicine of KRAS G12D-mutated cancers.