Efficacy of immune checkpoint inhibitors in advanced non‐small cell lung cancer patients with KRAS mutations: A network meta‐analysis

Abstract Objective Previous studies have shown that immune checkpoint inhibitors can improve the survival of patients with advanced non‐small cell lung cancer with KRAS mutations; however, there is a lack of comparisons between treatment regimens associated with immune checkpoint inhibitors, and our study aims to compare several treatment parties to find a more effective treatment regimen. Method A comprehensive literature search was conducted across multiple databases, namely PubMed, Web of Science, Embase, and Cochrane Library, to identify relevant studies. The screened studies were thoroughly examined, and data were collected to establish a Bayesian framework. The study focused on two primary endpoints: overall survival (OS) and progression‐free survival (PFS). Data analysis and graphical plotting using R software and Revman (version 5.3). It is worth mentioning that the study protocol was registered with the International Prospective Registry for Systematic Reviews, ensuring transparency and adherence to predetermined protocols (CRD42022379595). Result In total, our analysis included six RCTs involving 469 patients with KRAS mutations. Among these patients, 224 received chemotherapy, while 245 were treated with immune checkpoint inhibitors. Meta‐analysis results showed that the addition of ICIs could significantly improve OS and PFS (0.69, 95% CI 0.55, 0.86; 0.57, 95% CI 0.42, 0.77). The results of the network meta‐analysis showed that Pembrolizumab could improve OS (HR 0.42, 95% CI 0.22–0.80) and Pembrolizumab emerged as the most effective treatment option for enhancing OS in patients (SUCRA 65.03%). Additionally, pembrolizumab in combination with chemotherapy showed improvement in PFS (HR 0.47, 95% CI 0.29–0.76). Conclusion Our analysis found that among advanced NSCLC patients with KRAS gene mutations, first‐line treatment with pembrolizumab alone demonstrated greater efficacy. Similarly, second‐line treatment with nivolumab alone was found to be more effective in this patient population. However, the sample size of this study was limited, Therefore, additional clinical data is necessary to validate this finding in subsequent research.

demonstrated greater efficacy.Similarly, second-line treatment with nivolumab alone was found to be more effective in this patient population.However, the sample size of this study was limited, Therefore, additional clinical data is necessary to validate this finding in subsequent research.
K E Y W O R D S immune checkpoint inhibitors, KRAS mutation, network meta-analysis, non-small cell lung cancer, programmed cell death ligand-1, programmed cell death-1

| INTRODUCTION
Lung cancer, being one of the most devastating and lethal malignancies globally, particularly non-small cell lung cancer (NSCLC), represents the predominant histological subtype among lung cancer cases. 1 Previous research has consistently demonstrated that the KRAS gene plays an important role as a causal gene in NSCLC and is frequently mutated.Mutations in the KRAS gene are particularly common in people who are current or former smokers. 2,3At present, platinum-doublet chemotherapy remains the standard first-line treatment of choice for NSCLC patients who do not have driver gene mutations.Targeted therapies are mainly focused on patients with EGFR mutations, ALK mutations, and ROS1 mutations.Additionally, significant progress has also been made in targeted therapies for other less common driver gene mutations.5][6] Patients with NSCLC who have KRAS mutations generally exhibit a lower overall survival rate compared to those with KRAS wild-type. 48][9] Tumor development is intricately interconnected with the immune system.The immune checkpoint molecules, including cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed death receptor-1 and its ligand (PD-1/PD-L1), play a significant role in facilitating immune evasion by tumor cells.Immune checkpoint inhibitors (ICIs), which specifically target CTLA-4 and PD-1/PD-L1, have demonstrated the potential to restore immune cell activity against tumor cells and mitigate immune evasion.These inhibitors enhance the immune response and inhibit tumor growth by modulating interactions between tumor cells, antigen-presenting cells, and T cells. 10,11ecently, ICIs have shown promising clinical efficacy and significantly improved patient outcomes in NSCLC.
3][14][15] Most studies have focused on examining EGFR mutations, with little attention paid to KRAS mutations.However, recent evidence suggests that NSCLC patients with KRAS mutations may experience greater benefits from ICIs than those with EGFR mutations. 16Clinical studies have collected survival data on patients with KRAS mutations in the context of ICIs.However, there is a lack of comprehensive pooled analyses and systematic comparisons across various classes of ICIs.To address this, we conducted a network meta-analysis (NMA) to evaluate the efficacy and ranking of different treatment regimens involving ICIs in NSCLC patients with KRAS mutations.The aim was to provide useful insights for developing clinical treatment strategies that are tailored to NSCLC patients with KRAS mutations identified through genetic testing.

| Literature search strategies
Two researchers conducted separate searches on Web of Science, the Cochrane Library, Embase, and PubMed, until October 8, 2023.In case of any discrepancies, a third researcher resolved the conflicts.The study adhered to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). 17dditionally, the research protocol was registered with the International Prospective Registry for Systematic Reviews, with the registration code: CRD42022379595.The search terms were extracted based on the PICOS principles, including three subject terms ("immune checkpoint inhibitors," "non-small cell lung cancer," "randomized controlled trial") and eleven specific names of immune checkpoint inhibitors ("Nivolumab," "Pembrolizumab," "Avelumab," "Atezolizumab," "Tremelimumab," "Camrelizumab," "Durvalumab," "Sintilimab," "Ipilimumab," and "Sugemalimab").

| Inclusion criteria
1. Patients with histologically and cytologically confirmed metastatic or advanced NSCLC. 2. Hazard ratios (HR) with 95% confidence intervals (CI) were reported for OS and progression-free survival (PFS) in those patients who had KRAS mutations.3. Phase II or III RCTs. 4. ICIs were employed in the treatment.

| Data extraction and data analysis
We extracted various information, including the first author, study name, number of patients, interventions, year of publication, and risk ratios with 95% CI for OS and PFS.Each included study was assessed for risk of bias using the Cochrane Risk of Bias Assessment Tool, categorized as low risk, unclear, or high risk.
Statistical analyses were performed using the "JAGS" and "GeMTC" packages in R, as well as RevMan (version 5.3).The study endpoints were PFS and OS.A fixed-effects model with 2000 simultaneous iterations on three independent Markov chains was employed.Each chain underwent 50 000 sample iterations.The treatments were ranked from best to worst using the probability ranking command, and the two-sided difference was assessed for statistical significance (α < 0.05).To evaluate study heterogeneity, we utilized I 2 values.I 2 values below 25% indicate low heterogeneity, suggesting the use of a fixed-effects model.3 | RESULT

| Literature search results
A total of 5650 articles related to the literature search were identified for this study.][20][21][22][23] The analysis and results in this subgroup might not include the influence of PD-L1 expression on treatment outcomes.The search and exclusion process can be referred to in Figure 1 for a visual representation of the study selection process.The final inclusion of T A B L E 1 Baseline characteristics of studies included in the network meta-analysis.

Study
Auther 469 patients involved six treatment modalities: chemotherapy, ipilimumab plus nivolumab, nivolumab, chemotherapy plus pembrolizumab, atezolizumab, and pembrolizumab.5][26] Survival data for patients with KRAS mutations in the POPLAR trial were derived from a meta-analysis. 27The risk of risk plot is shown in Figure 3.

| Pairwise meta-analysis
When comparing ICIs with chemotherapy, we conducted a paired analysis (Figure 4).Six trials report HRs for OS.There was low heterogeneity among the studies (P = 0.51, I 2 = 0%) and a fixedeffects model was used.Three trials report PFS with low heterogeneity across studies (p = 0.29, I 2 = 18%), which were also analyzed using fixed-effects models.The inclusion of ICIs demonstrated significant improvements in both OS and PFS compared to chemotherapy, with respective hazard ratios of 0.69 (95% CI 0.55-0.86)and 0.57 (95% CI 0.42-0.77).

| Network meta-analysis
A ranking table was created in the NMA (Figure 6).Both ICIs demonstrated superior efficacy compared to chemotherapy.PEM as a monotherapy significantly improves OS and PFS in patients (HR 0.42, 95% CI 0.22 0.80; HR 0.51, 95% CI 0.30 0.89).Additionally, the OS of various treatment regimens was compared separately in first-line and second-line treatment settings (figure 5).In first-line treatment, PEM exhibited a significant improvement in patients' OS (HR 0.42, 95% CI 0.22 0.79), while in second-line treatment, NIV significantly improved patients' OS (HR 0.52, 95% CI 0.29 0.94).

| Ranking
The effectiveness of treatment options was evaluated and ranked in terms of their probability in Figure 6.Based on our findings, PEM emerged as the most effective treatment option for enhancing OS in patients (SUCRA 65.03%).Additionally, when combined with chemotherapy, pembrolizumab demonstrated superior efficacy in improving PFS (SUCRA 75.39%).

| DISCUSSION
This NMA investigates the optimal treatment strategies for ICIs in NSCLC patients with KRAS mutations.OS serves as the primary and most reliable indicator of antineoplastic drug efficacy, forming the foundation for our research and subsequent discussions.The findings from the current study confirm that patients with KRAS gene mutations derive greater survival benefits from immunotherapy, which is consistent with earlier research. 27,28atients with KRAS mutations exhibit increased levels of PD-1/PD-L1 expression.These mutations are proposed to independently affect PD-1 positivity, leading to an increase in PD-L1 expression.0][31] These mechanisms may collectively contribute to the improved survival benefits observed in patients with KRAS mutations, enhancing the efficacy of ICIs.Additionally, this study expands on the aforementioned research by ranking the effectiveness of various immunotherapy treatment options.The findings of the study indicate that pembrolizumab emerges as the most effective treatment option for enhancing OS.Furthermore, the combination of pembrolizumab with chemotherapy demonstrates superior efficacy in improving PFS.Among those patients, PD-1 inhibitors were slightly more effective than PD-L1 inhibitors.Moreover, the combination of PD-1 inhibitors with CTLA-4 inhibitors did not yield any notable improvement in efficacy.This finding is consistent with a previous metaanalysis conducted in the context of NSCLC. 32Theoretical suggestions suggest that PD-L1 inhibitors may have the potential to achieve more substantial clinical effects compared to PD-1 inhibitors by blocking both pathways, and it is speculated that the difference between this result and the results of our pooled analysis is due to the ignoring of the role of other cytokines, TIME, and other related factors. 33enetic testing has become increasingly common in clinical treatment due to the development of medical treatment and the focus on personalization and precision.Genetic testing results are frequently employed by healthcare professionals to guide treatment decisions for patients.One of the genes commonly tested is the KRAS gene.This study aims to serve as a reference for patients who have undergone genetic testing and know whether the gene is mutated or not.It will help them choose a more accurate and suitable treatment plan, preventing patients from missing the best time for treatment.The researchers also examined the effect of the gene on F I G U R E 6 A) Network meta-analysis of OS; B) ranking of OS; C) network meta-analysis of PFS; D) ranking of PFS. the drug's efficacy.KRAS is a GTPase that plays a crucial role in cell signaling.KRAS mutations have distinctive effects on downstream signaling pathways, with different mutations stimulating various signaling cascades.Consequently, the efficacy of the same drug can vary across different mutations in the KRAS locus, resulting in differing survival rates.For instance, the G12D mutation has been associated with worse overall survival.5][6] The G12D mutation in the KRAS gene has been found to be negatively correlated with PD-L1 expression during the establishment of a TIME that is resistant to ICIs.This correlation may contribute to the poor efficacy observed in patients with the G12D mutation.Notably, paclitaxel has been shown to improve the tumor immune microenvironment in cases involving the G12D mutation.Therefore, the combination of ICIs and chemotherapy, specifically paclitaxel, may lead to improved clinical efficacy for patients with NSCLC who have the KRAS G12D mutation. 34This emphasizes the significance of tailoring treatment regimens based on individual genetic factors.][9] There are several limitations to this study.Firstly, the small sample size obtained from only six randomized clinical controlled trials hinders the establishment of strong and conclusive evidence.Further validation through a larger number of clinical trials or real-world studies is necessary.This limitation represents the study's primary constraint.Secondly, this study did not explore adverse reactions in NSCLC patients with KRAS mutations.The study solely focused on the efficacy of the five treatments and did not analyze their safety profile.Additionally, the study primarily relied on published data regarding KRAS mutations and did not specifically examine the survival outcomes in patients with varying PD-L1 expression.Therefore, there was insufficient discussion on the effectiveness of treatment in patients with KRAS gene mutations in the presence of varying PD-L1 expression.

| CONCLUSION
In conclusion, our NMA compared the efficacy of various treatments involving ICIs for advanced NSCLC patients with KRAS mutations.The results showed that PD-1 inhibitors, particularly pembrolizumab, were more effective in improving patients' OS and PFS, followed by nivolumab based on the rankings.However, in order to provide robust support and validation for our conclusions, additional clinical data is required.Furthermore, continued and sustained follow-up is necessary to ensure the reliability and long-term assessment of our findings.

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I G U R E 1 Describes a flowchart for retrieving and screening.

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I G U R E 2 Comparative efficacy of different immune checkpoint inhibitors in patients with advanced or metastatic NSCLC with KRAS mutations network diagrams.Purple line: OS network plot, yellow line: PFS network plot.Each circle represents an intervention node in the network and the line width is proportional to the number of RCT trials.Chemo, chemotherapy; Niv, nivolumab; Pem, pembrolizumab; Ate, atezolizumab; Ipi, ipilimumab.F I G U R E 3 Risk of bias figure.

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I G U R E 4 A) Forest plot of OS； B) forest plot of PFS; efficacy of ICIs versus chemotherapy in patients with KRAS mutations in advanced NSCLC.

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I G U R E 5 A) NMA of OS for first-line treatment; B) NMA of OS for second-line treatment.
Data of studies included in the network meta-analysis.