Therapeutic impact of mutation subtypes and concomitant <i>STK11</i> mutations in <i>KRAS</i>–mutated non-small cell lung cancer (NSCLC): A result of nationwide genomic screening project (LC-SCRUM-Japan).

<jats:p> 9589 </jats:p><jats:p> Background: KRAS mutations are one of the common oncogene drivers in non-small cell lung cancer (NSCLC), and the development of several targeted drugs for KRAS-mutated NSCLC is now ongoing. However, the clinical impact of KRAS mutation subtypes or concomitant other gene mutations in NSCLC patients (pts) remains unclear. Methods: In a nationwide genomic screening project (LC-SCRUM-Japan), we have prospectively analyzed lung cancer pts for genetic alterations and tumor mutation burden (TMB) by next-generation sequencing system, and for PD-L1 expression by immunohistochemistry (22C3 antibody). The therapeutic efficacy and survival of KRAS-mutated non-squamous (non-sq) NSCLC pts were evaluated using a clinico-genomic database of the LC-SCRUM-Japan. Results: A total of 5166 non-sq NSCLC pts enrolled from 2015 to 2019. KRAS mutations were detected in 794 pts (15%; G12C/G12D/G12V/G12A/G13X/others = 232/186/165/66/61/84). Among the 794 pts, TMB and PD-L1 expression were analyzed in 128 and 79, respectively, and 218 received PD-1/PD-L1 inhibitors (IO) after 1st-line chemotherapy. The median age was 66 years (range, 29-89). 142 pts (65%) were male and 172 (78%) were smokers. Concomitant STK11 mutations were detected in 33 pts (15%) with no difference in the mutation frequency among KRAS mutation subtypes. KRAS G12C was significantly associated with high TMB (≥ 10 mut/Mb) (p = 0.03), and KRAS G12C or G12V with high PD-L1 expression (≥ 50%) (p = 0.02). In pts who received IO, median progression-free survival (mPFS) was significantly longer in pts with KRAS G12C or G12V than in those with other KRAS mutations (4.7 vs 2.0 months, hazard ratio (HR) 0.58 [95%CI 0.43-0.78], p < 0.01). Among pts with KRAS G12C or G12V, mPFS of IO was significantly shorter in pts with concomitant STK11 mutations than in those without (1.8 vs. 5.7 months, HR 1.97 [95%CI 1.06-3.41], p = 0.02). These correlations were not observed in platinum-containing chemotherapy (Plt-CTx). There were also no significant differences in IO and Plt-CTx efficacies between with and without other concomitant mutations, such as TP53, RB1, CDKN2A and PTEN mutations. Conclusions: Non-sq NSCLC pts with KRAS G12C/V were more sensitive to IO therapies than those with other KRAS mutations, but KRAS G12C/V-positive pts with concomitant STK11 mutations were less sensitive than those without. These results could be highly informative in the development of novel targeted therapies for KRAS-mutated NSCLC. </jats:p>