Introduction
In recent years, immune checkpoint inhibitors (ICIs) that target the PD-1/PD-L1 axis have become an integral part of clinical practice [
1,
2]. They have revolutionized the treatment of various cancers, including non-small cell lung cancer (NSCLC), head and neck squamous cell carcinoma (HNSCC), renal cell carcinoma (RCC), urothelial cancer (UC), melanoma, and hepatocellular carcinoma (HCC) [
3,
4]. While ICI therapy has demonstrated remarkable response rates and long-term survival in advanced cancer patients, its high cost presents economic challenges. Moreover, not all patients benefit equally from immunotherapy [
5]. A comprehensive analysis of 262 patients with different malignancies revealed an overall objective response rate (ORR) of 29% and a long-term survivor rate (i.e., longer than 2 years) of 11.8% [
6]. It is worth noting that the immune-related adverse effects of ICI therapy can lead to severe and, in some cases, fatal consequences [
7].
In recent years, there has been an increasing emphasis on the early identification of non-responsive individuals to ICI therapy in cancer treatment to avoid ineffective treatments and reduce the risk of adverse effects [
8,
9]. Numerous predictive biomarkers have been studied for their association with the ICI response, such as intratumoral PD-L1 expression, tumor mutational burden, T-cell infiltration metrics, and the use of antibiotics and acid suppressants [
5,
10]. Nevertheless, establishing consistent criteria for quantifying these markers remains a challenge. At present, the only marker that has received regulatory approval as a companion diagnostic for ICI treatment is the detection of intratumoral PD-L1 [
11,
12]. However, the predictive value of PD-L1 expression has not been clarified and recently published meta-analyses come to different conclusions [
13,
14]. Therefore, it is crucial to identify novel prognostic biomarkers that can enhance the outcomes of cancer patients undergoing ICI therapy.
Blood tests offer several advantages, including clinical applicability, simplicity, affordability, and the ability to provide objective analysis from virtually anywhere. Cancer tumorigenesis and metastasis are associated with systemic inflammation and malnutrition, and there is a mounting body of evidence emphasizing the pivotal role of inflammation in cancer progression [
15]. Nutritional and inflammatory indicators, with the most extensively studied ones being albumin and neutrophil-to-lymphocyte ratio (NLR), have demonstrated the ability to predict the efficacy of ICI therapy in oncology patients [
8,
16]. In 2013, Jafri et al. incorporated NLR, albumin, and body mass index (BMI) into a model, and it was revealed that advanced lung cancer inflammation index (ALI) might help predict survival outcomes in various tumors [
17,
18]. The Gustave Roussy Immune (GRIm) score, a prognostic tool, combines three key biomarkers: NLR, albumin, and lactate dehydrogenase (LDH). By combining these factors, patients can be categorized into high-risk and low-risk groups, with those with a GRIm score > 1 considered to have a high score [
19‐
21]. The predictive value of the GRIm score has been extensively studied in patients with advanced NSCLC who have received various treatments, including cytotoxic chemotherapy, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), or second-line immunotherapy [
19‐
21]. Besides, an improved GRIm score (hepatocellular carcinoma modified Gustave Roussy Immune Score, HCC-GRIm score) was proposed by Li et al. [
22]. Compared to the original GRIm-Score, they discovered that the HCC-GRIm-Score had higher predictive power in identifying the HCC patients potentially benefiting from ICIs therapy [
22].
The correlation between ALI levels, GRIm score, and the prognosis of cancer patients receiving ICI therapy has yielded conflicting results, and a comprehensive meta-analysis on this topic is currently lacking. Hence, the aim of this study was to systematically evaluate the predictive significance of ALI levels and GRIm score in cancer patients undergoing ICI therapy. The results of this investigation possess the capability to significantly contribute to the advancement of ICIs. This contribution lies in facilitating the delivery of precise, cost-effective treatments and minimizing adverse effects.
Discussion
Our study aimed to investigate the prognostic implications of the ALI and GRIm score in cancer patients receiving ICI therapy. Through a comprehensive meta-analysis of relevant studies, we established a strong correlation between higher ALI levels, a lower GRIm score, and improved OS and PFS. Furthermore, subgroup analysis revealed that ALI cutoff values of 18 demonstrated higher predictive potential.
The systemic inflammation observed in cancer patients stems from various factors, including cancer itself, the release of inflammatory mediators by leukocytes, and tissue inflammation triggered by tumor growth or invasion [
42‐
44]. Inflammatory markers have proven to be valuable predictors because systemic inflammatory responses contribute to cancer progression, invasion, and metastasis [
45‐
47]. In patients undergoing ICI therapy, cytokines and chemokines produced by neutrophils can promote angiogenesis and remodeling of the extracellular matrix [
48,
49]. This, in turn, creates a favorable microenvironment for cancer growth and influences the effectiveness of ICIs [
50,
51]. Additionally, lymphocytes play a critical role in antitumor immune responses by recognizing cancer cell antigens [
52], and these biomarkers may reflect the immune status of patients and their response to ICIs [
53].
Several studies have demonstrated the significance of the NLR as a predictive marker for therapeutic response to ICIs in various cancers [
54,
55]. Elevated levels of proinflammatory cytokines, such as osteopontin and interleukin-6, have been associated with poor outcomes in cancer [
56,
57]. Furthermore, a higher NLR value is often correlated with increased proinflammatory cytokine levels [
58,
59]. Furthermore, higher NLR values contribute to increased infiltration of macrophages in the tumor microenvironment, leading to resistance to ICIs [
60].
Historical investigations have established a correlation between malnutrition and an unfavorable tumor prognosis [
43,
61]. Although diminished levels of albumin serve as an indicator of malnutrition, they concurrently function as a biomarker for systemic inflammation [
62‐
64]. Previous studies have demonstrated that inflammatory elements impede albumin synthesis, and oxidative stress can induce albumin denaturation, thereby contributing to a swift decline in serum albumin concentrations among individuals experiencing an inflammatory condition [
65,
66]. Besides, LDH levels reflect tumor growth and invasiveness in cancer, as LDH is involved in the metabolism of pyruvate to lactic acid [
67]. Several studies have reported that elevated LDH levels are predictive of poor prognosis in ICI-treated patients with various cancers [
68,
69]. Considering that the ALI and GRIm score incorporate NLR and Alb, it is believed to provide an even stronger indication of resistance to ICI treatment in patients with advanced cancer.
In this investigation, we conducted an initial meta-analysis to validate the prognostic utility of the ALI and GRIm score in evaluating the responsiveness of cancer patients to ICI therapy. The ALI and GRIm score offer a multitude of advantages that render them suitable for routine clinical applications. Their accessibility, facile quantifiability, reproducibility, and comparatively economical nature make them highly amenable for assessment [
70]. Consequently, owing to their firmly established influence on the nutritional and immune status of the host, as well as their impact on cancer, the ALI and GRIm score stand poised as valuable instruments for predicting the therapeutic outcomes of ICIs in cancer patients. Tailored and timely nutritional and immunological interventions have the potential to enhance the prognosis of individuals afflicted with cancer.
It is important to highlight that all studies included in our analysis were retrospective studies, which may introduce limitations in terms of statistical validity. Besides, the vast majority of studies included in this analysis were NSCLC and HCC, and the role of ALI and GRIm in other cancers remains to be further investigated. There are too few studies included in the analysis of HCC-GRIm, and more studies are needed for a comprehensive analysis. Therefore, there is a critical need for additional rigorous investigations with larger sample sizes, specifically multicenter prospective studies, to validate and enhance the robustness of our findings. The role of ALI and GRIm in predicting toxicities during immunotherapy should also be further explored in the future.
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