Osimertinib in combination with anti-angiogenesis therapy presents a promising option for osimertinib-resistant non-small cell lung cancer.

BACKGROUND: Osimertinib has become standard care for epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC) patients whereas drug resistance remains inevitable. Now we recognize that the interactions between the tumor and the tumor microenvironment (TME) also account for drug resistance. Therefore, we provide a new sight into post-osimertinib management, focusing on the alteration of TME. METHODS: We conducted a retrospective study on the prognosis of different treatments after osimertinib resistance. Next, we carried out in vivo experiment to validate our findings using a humanized mouse model. Furthermore, we performed single-cell transcriptome sequencing (scRNA-seq) of tumor tissue from the above treatment groups to explore the mechanisms of TME changes. RESULTS: Totally 111 advanced NSCLC patients have been enrolled in the retrospective study. The median PFS was 9.84 months (95% CI 7.0-12.6 months) in the osimertinib plus anti-angiogenesis group, significantly longer than chemotherapy (P = 0.012) and osimertinib (P = 0.003). The median OS was 16.79 months (95% CI 14.97-18.61 months) in the osimertinib plus anti-angiogenesis group, significantly better than chemotherapy (P = 0.026), the chemotherapy plus osimertinib (P = 0.021), and the chemotherapy plus immunotherapy (P = 0.006). The efficacy of osimertinib plus anlotinib in the osimertinib-resistant engraft tumors (R-O+A) group was significantly more potent than the osimertinib (R-O) group (P<0.05) in vitro. The combinational therapy could significantly increase the infiltration of CD4+ T cells (P<0.05), CD25+CD4+ T cells (P<0.001), and PD-1+CD8+ T cells (P<0.05) compared to osimertinib. ScRNA-seq demonstrated that the number of CD8+ T and proliferation T cells increased, and TAM.mo was downregulated in the R-O+A group compared to the R-O group. Subtype study of T cells explained that the changes caused by combination treatment were mainly related to cytotoxic T cells. Subtype study of macrophages showed that proportion and functional changes in IL-1ß.mo and CCL18.mo might be responsible for rescue osimertinib resistance by combination therapy. CONCLUSIONS: In conclusion, osimertinib plus anlotinib could improve the prognosis of patients with a progressed disease on second-line osimertinib treatment, which may ascribe to increased T cell infiltration and TAM remodeling via VEGF-VEGFR blockage.

EGFR-targeted therapy alters the tumor microenvironment in EGFR-driven lung tumors: Implications for combination therapies.

Immune checkpoint inhibitors targeting the programmed cell death receptor/ligand 1 (PD-1/PD-L1) pathway have profoundly improved the clinical management of non-small-cell lung cancer (NSCLC). Nevertheless, the superiority of single-agent PD-1/PD-L1 inhibitors in pretreated EGFR mutant patients has turned out to be moderate. One proposed mechanism for poor response to immune checkpoint inhibitors is an immunosuppressive tumor microenvironment. Therefore, we utilized two autochthonous EGFR-driven lung tumor models to investigate dynamic microenvironmental responses to EGFR-TKI treatment. We observed that at an early stage, sensitive EGFR-TKIs caused obvious tumor shrinkage accompanied by increased cytotoxic CD8+ T cells and dendritic cells, eradication of Foxp3+ Tregs, and inhibition of M2-like polarization of macrophages. However, the tumor microenvironmental changes that may be most beneficial for combination treatment with immune-mediated anticancer approaches were only temporary and disappeared as treatment continued. Meanwhile, the level of myeloid-derived suppressor cells (MDSCs), particularly mononuclear MDSCs, was consistently elevated throughout the treatment. Analysis of inflammatory factors in serum showed that EGFR-TKIs increased the levels of IL-10 and CCL-2. Our study systematically analyzed dynamic changes in tumor microenvironments responding to EGFR-TKIs in vivo. The results have implications for combination therapy using EGFR-TKIs. The optimal sequence of the treatment and strategies that modulate the tumor microenvironment to a state that may favor antitumor immune responses need to be considered when designing clinical trials.

Navigation improves the learning curve of transforamimal percutaneous endoscopic lumbar discectomy.

PURPOSE: Beginners usually need increased punctures and dozens of fluoroscopy in learning transforamimal percutaneous endoscopic lumbar discectomy (tPELD). Navigator-assisted spinal surgery (NASS) is a novel technique that could induce a definite trajectory. The retrospective study aimed to investigate the impact of a definite trajectory on the learning curve of tPELD. METHODS: A total of 120 patients with symptomatic lumbar disc herniation who received tPELD between 2012 and 2014. Patients receiving tPELD with NASS technique by one surgeon were regarded as group A, and those receiving conventional methods by another surgeon were regarded as group B. Each group was divided into three subgroups (case 1-20, case 21-40, case 41-60). RESULTS: The fluoroscopy times were 22.62 ± 3.80 in group A and 34.32 ± 4.78 in group B (P < 0.001). The pre-operative location time was 3.56 ± 0.60 minutes in group A and 5.49 ± 1.48 minutes in group B (P < 0.001). The puncture-channel time was 21.85 ± 4.31 minutes in group A and 34.20 ± 8.88 minutes in group B (P < 0.001). The operation time was 84.62 ± 9.20 minutes in group A and 101.97 ± 14.92 minutes in group B (P < 0.001), and the learning curve of tPELD in group A was steeper than that in group B. No significant differences were detected in patient-reported outcomes, hospital stay, patient satisfaction, and complication rate between the two groups (p > 0.05). CONCLUSIONS: Definite trajectory significantly reduced the operation time, preoperative location time, puncture-channel time, and fluoroscopy times of tPELD by beginners, and thus reshaped the learning curve of tPELD and minimized the radiation exposure.

Tumour microenvironment changes after osimertinib treatment resistance in non-small cell lung cancer.

BACKGROUND: Growing evidence suggests that acquired resistance to targeted therapy in non-small cell lung cancer patients is linked to the mutual domestication between the tumour and its surrounding microenvironment. AIM: Our study aims to explore the remodelling of tumour microenvironment after osimertinib treatment resistance. METHODS: We took RNA-seq-based tumour immune infiltration analysis using the TIMER 2.0. We carried out flow cytometry assay and real-time cell analysis to explore the interaction between tumour cells and immune cells. In addition, we analysed exosomes via miRNA-seq and label-free proteomics. RESULTS: Immune infiltration estimation showed a significant decrease in the immune score (P < 0.001), microenvironment score (P < 0.001) and CD8+ T cells (P < 0.05), but an increase in M0 macrophages (P < 0.01) at osimertinib resistance compared to pre-treatment patients. It was demonstrated that exosomes from H1975OR cells could be taken up by macrophages and drove their polarisation towards the M2 phenotype, and the polarised M2 macrophages could reduce the inhibitory effect on tumour cell proliferation. Pre-activated peripheral blood mononuclear cells exhibited a more potent killing effect on H1975OR cells. We also detected a decrease in CD4+HLA-DR- T cells and an increase in CD4+PD1+ T cells after being co-cultured with H1975OR derived exosomes or conditioned medium. Further miRNA-seq and proteomics analysis of exosomes demonstrated that mir-1258-3p and miR-17-5p might participate in this interaction. CONCLUSIONS: An immunosuppressive environment, characterised by decreased T cell infiltration and activation, whereas increased macrophage infiltration and M2 polarisation, was identified at osimertinib resistance. This interaction may be carried out by tumour-derived exosomes.

Single-Cell Profiling of Tumor-Associated Neutrophils in Advanced Non-Small Cell Lung Cancer.

Purpose: Neutrophils act as a non-negligible regulator in the initiation and progression of malignancies, playing bifacial roles in the process. Thus, to understand the heterogeneity of tumor-associated neutrophils (TANs) comprehensively in advanced non-small cell lung cancer (NSCLC) at single-cell resolution is necessary and urgent. Materials and Methods: We applied single-cell RNA-sequencing (scRNA-seq) to portray the subtype-specific transcriptome landscape of TANs in advanced NSCLC using nine freshly obtained specimens. The scRNA-seq data were further processed for pseudo-time analysis to depict the developmental trajectory of TANs. Meanwhile, the interplay between TANs and other cell types within tumor microenvironment (TME) was revealed by intercellular interaction analysis. Results: Seven distinct TAN subtypes were defined, of which, the N3 cluster was considered inflammatory phenotype expressing genes encoding multiple chemotactic cytokines, and correlated with inferior overall survival, indicating that N3 might be a pro-tumorigenic TAN subtype. N1 and N5 clusters were considered to be well differentiated and mature neutrophils based on CXCR2 expression and pseudo-time patterns, and both accounted for relatively high proportions in lung adenocarcinoma. In addition, genes related to neutrophil differentiation were discovered. We also found that TAN subtypes interacted most closely with macrophages through chemokine signaling pathways within TME. Conclusion: Our study refined TAN subtypes and mapped the transcriptome landscape of TANs at single-cell resolution in advanced NSCLC, collectively indicating the heterogeneity of TANs in NSCLC. Neutrophil differentiation- and maturation-related genes were also discovered, which shed light on different functions of TAN subclones in tumor immune escape, and may further provide novel targets for immunotherapy.

Patients With Short PFS to EGFR-TKIs Predicted Better Response to Subsequent Anti-PD-1/PD-L1 Based Immunotherapy in EGFR Common Mutation NSCLC.

BACKGROUND: Despite disappointing outcomes from immuno-monotherapy, studies reported that NSCLC patients with EGFR mutation may possibly benefit from combined immunotherapy. Whether the response to prior EGFR-TKI has association with the outcomes of subsequent immunotherapy remains unclear. PATIENTS AND METHODS: Advanced NSCLC patients with resistance to EGFR-TKIs and received ICI treatment from January 2016 to June 2019 were retrospectively analyzed. Single cell sequencing and flow cytometry were conducted to explore the difference of cell components in tumor microenvironments (TME). A 1:3 matched case-control study was conducted to compare the clinical effects of combined immunotherapy with standard chemotherapy as second-line treatment. RESULTS: Fifty-eight patients treated with anti-PD-1/PD-L1 based immunotherapy behind EGFR-TKI treatment were enrolled. Correlation analysis showed TKI-PFS had a significantly negative association with corresponding IO-PFS (r = -0.35, p = 0.006). TKI-PFS cutoff 10 months had the most significant predictive function for posterior immunotherapy and was validated to be an independent predictor by uni- and multivariate analyses. Kaplan-Meier analysis showed that patients with TKI-PFS less than 10 months had significantly prolonged IO-PFS and higher ORR than those with long (median PFS, 15.1 vs 3.8 months; HR, 0.26, p = 0.0002; ORR, 31.8 versus 10%, p = 0.04). Single cell RNA-seq revealed that the cell components were varied among patients after treatment with EGFR-TKI. Patients with short TKI-PFS demonstrated a relatively higher proportion of CD8 effector cells and lower ratio of M2 like macrophage to M1 like macrophages, which was validated by flow cytometry. Case-control study demonstrated that combined immunotherapy achieved significantly longer PFS (HR, 0.51, 95% CI: 0.31-0.85, p = 0.02), longer OS (HR, 0.48, 95% CI: 0.26-0.89, p = 0.05) and higher ORR (33.3 vs 10.0%, p = 0.02) than traditional chemotherapy for patients with short TKI-PFS. CONCLUSION: Patients with short TKI-PFS conferred better response to immunotherapy than those with long. The status of TME were different among those two populations. Combined ICI treatment could promisingly be a better choice than classical chemotherapy in second-line setting for patients with short TKI-PFS and no T790M mutation. Underlying mechanisms need to be further explored.

The safety and efficacy of immunotherapy with anti-programmed cell death 1 monoclonal antibody for lung cancer complicated with Mycobacterium tuberculosis infection.

BACKGROUND: Anti-programmed cell death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) immunotherapy has boosted the prognosis in advanced lung cancer. Meanwhile, accumulating cases showed the correlation between tuberculosis (TB) reactivation and anti-PD-1/PD-L1 immunotherapy. However, the safety and efficacy of anti-PD-1/PD-L1 immunotherapy for lung cancer complicated with TB infection could only be learned from real-world data. METHODS: We retrospectively analyzed 562 patients with advanced lung cancer who received anti-PD-1/PD-L1 immunotherapy at Shanghai Pulmonary Hospital from 2015 to 2019, including 13 patients with TB infection. Besides, relevant literature reviews were performed online to analyze the safety and efficacy of immunotherapy and to explore the appropriate treatment strategies in this specific population. RESULTS: In our cohort, the initiation of anti-PD-1/PD-L1 immunotherapy was from June 2015 to December 2019. Among them, 13 patients had TB infection prior to immunotherapy including 11 latent TB and 2 active TB, and all of them were treated with anti-PD-1 immunotherapy. Patients with active TB infection were treated with concurrent anti-TB and anti-PD-1 treatments, and the remaining received either mono-immunotherapy or combined immunotherapy. Neither reactivation of latent TB nor progression of active TB was monitored in our cohort during immunotherapy. Severe immune-related adverse events (irAEs) were diagnosed in two patients. Treatment strategies such as discontinuation of immunotherapy and administration of corticosteroids were provided timely, and one with latent TB infection got gradually improved, but the other one with active TB died quickly. The median progression-free survival (PFS) was 5.5 months for tumor immunotherapy in our cohort. However, the PFS of immunotherapy was merely 2.1 and 2.2 months in lung cancer patients with active TB infection. CONCLUSIONS: Immunotherapy is relatively safe for lung cancer patients complicated with previously treated latent TB, and the efficacy of immunotherapy in this specified population is not inferior to that in lung cancer patients without TB infection. TB screening before anti-PD-1/PD-L1 immunotherapy is strongly recommended, and irAEs should be monitored more cautiously in lung cancer patients with active TB infection.

Concurrent use of metformin enhances the efficacy of EGFR-TKIs in patients with advanced EGFR-mutant non-small cell lung cancer-an option for overcoming EGFR-TKI resistance.

BACKGROUND: Resistance is almost inevitable and is still a major obstacle in epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) therapy. Only limited relevant clinical studies evaluated the therapeutic effects by combing metformin and EGFR-TKIs in non-small cell lung cancer (NSCLC) patients. Therefore, we evaluated the efficacy of concurrent use of metformin with EGFR-TKIs, and assessed whether the addition of metformin may improve clinical outcomes and delay the occurrence of EGFR-TKI resistance. METHODS: We conducted cell proliferation and apoptosis assay for investigation of metformin in combination with EGFR-TKIs to overcome EGFR-TKI resistance in vitro. Furthermore, we retrospectively reviewed clinicopathological characteristics and therapeutic outcomes of EGFR-mutant advanced NSCLC diabetic patients who received EGFR-TKIs with or without concurrent use of metformin. RESULTS: In vitro experiment, metformin showed synergistic interaction both with gefitinib in PC9R (CI =0.77) and with osimertinib in PC9R/OR (CI =0.77) in proliferation inhibition assay. Metformin can also augment apoptosis effect of these TKI-resistant cells to EGFR-TKIs. In retrospective cohort, a total of 85 patients were identified (cohort A), in which 28 patients had concurrent use of metformin. The objective response rate in metformin use group was significantly higher (85.7% vs. 47.4%, P=0.001). The median progression-free survival (PFS) and overall survival (OS) in metformin use group were significantly longer (21.6 vs. 9.2 months, P=0.000; 48.4 vs. 36.6 months, P=0.049). Further analysis revealed that metformin obviously prolonged the median PFS2 of osimertinib treatment among patients who progressed to prior line EGFR-TKIs due to secondary EGFR T790M mutation (cohort B). CONCLUSIONS: Our study suggest that concurrent use of metformin could be beneficial to EGFR-mutant NSCLC patients treated with either first-line EGFR-TKIs or second-line osimertinib.

Could tumor spread through air spaces benefit from adjuvant chemotherapy in stage I lung adenocarcinoma? A multi-institutional study.

BACKGROUND: The benefit of adjuvant chemotherapy (ACT) remains unknown for patients with stage I lung adenocarcinoma (ADC) with spread through air spaces (STAS). This study investigated the effect of adjuvant chemotherapy in stage I ADC/STAS-positive patients. METHODS: A total of 3346 patients with stage I ADC from five institutions in China were identified from 2009 to 2013, of whom 1082 were diagnosed with STAS (32.3%). By using the Kaplan-Meier method and Cox proportional hazard regression model, we explored the impact of STAS on prognosis, and determined if the use of adjuvant chemotherapy was associated with improved outcomes in patients with stage I ADC/STAS-positive. A validation cohort was also included in this study. RESULTS: Patients with stage I ADC/STAS-positive in the primary cohort had unfavorable overall survival (OS) and disease-free survival (DFS). A multivariate Cox regression model confirmed the survival disadvantages of STAS in patients with stage I ADC [OS: hazards ratio (HR) = 1.877, 95% confidence interval (CI): 1.579-2.231; p < 0.001; DFS: HR = 1.895, 95% CI: 1.614-2.225; p < 0.001]. Lobectomy was associated with better OS and DFS than sublobar resection (SR) in both stage IA and IB ADC/STAS-positive. Similar results were observed in the validation cohort. For patients with stage IB ADC/STAS-positive, ACT was revealed as an independent factor for favorable survival (OS: HR = 0.604, 95% CI: 0.397-0.919; p = 0.018; DFS: HR = 0.565, 95% CI: 0.372-0.858; p = 0.007). However, among patients with stage IA ADC/STAS-positive, ACT was associated with improved outcomes only for those undergoing SR (OS: HR = 0.787, 95% CI: 0.359-0.949; p = 0.034; DFS: HR = 0.703, 95% CI: 0.330-0.904; p = 0.029). CONCLUSION: The presence of STAS was correlated with poor prognosis in patients with stage I ADC. Our study suggested that ACT might be considered for patients with stage IB ADC/STAS-positive and those with stage IA ADC/STAS-positive who underwent SR.

Predictive and prognostic significance of M descriptors of the 8th TNM classification for advanced NSCLC patients treated with immune checkpoint inhibitors.

BACKGROUND: A strong association between M descriptors and prognosis of non-small cell lung cancer (NSCLC) has been demonstrated recently. However, its predictive and prognostic significance for advanced NSCLC patients treated with immune checkpoint inhibitors (ICIs) remain unclear. In this study, we aimed at investigating the impact of M descriptors on clinical outcomes in those patients. METHODS: A retrospective analysis was conducted. Patients treated with more than two cycles of ICIs were included. Detailed characteristics and clinical response after immunotherapy were recorded. M descriptors were classified into M1a, M1b, and M1c according to the 8th TNM classification. RESULTS: A total of 103 patients were enrolled, including 42 with M1a disease, 16 with M1b disease and 45 with M1c disease. Patients with M1a disease demonstrated significant longer median progress-free survival (PFS) (11.9 vs. 4.1 and 3.2 months, respectively, P=0.0002) and overall survival (OS) (35 vs. 22.1 and 12 months, P=0.02) than those with M1b and M1c disease. Patients with M1a disease showed higher objective response rate (ORR) (28.6% vs. 14.8%, P=0.08) and disease control rate (DCR) (81% vs. 59%, P=0.02) compared with those with M1b and M1c disease. Multivariate analysis identified M1a stage as being independently associated with prolonged PFS and had better OS than those with M1c disease (P=0.05) but not M1b disease (P=0.06). CONCLUSIONS: The current study demonstrated a clear association between M descriptors and the therapeutic response to ICIs and confirmed its prognostic role in advanced patients treated with ICIs monotherapy. M descriptors may need to be stratified in future study design.

Impact of EGFR-TKIs combined with PD-L1 antibody on the lung tissue of EGFR-driven tumor-bearing mice.

OBJECTIVES: EGFR-targeted tyrosine kinase inhibitors (TKIs) have been the standard treatment for non-small cell lung cancer patients with EGFR mutations. However, most patients eventually develop resistance. With the development of immune checkpoint inhibitors targeting the programmed cell death receptor/ligand 1 (PD-1/PD-L1), there is a growing interest in developing combination strategies. However, there are concerns that the combination of a PD-(L)1 inhibitor and EGFR-TKI may be associated with an increased risk of pneumonitis. Therefore, we utilized an established EGFR-driven tumor-bearing mouse model to investigate whether the combination would induce pneumonitis in mouse lung tissue. MATERIALS AND METHODS: Mice were treated with monotherapy or combined therapy of PD-L1 antibody and EGFR-TKIs including first-generation gefitinib and third-generation osimertinib. Bronchoalveolar lavage fluids (BALFs) and lung tissues were collected for analysis at the end of treatment. RESULTS AND CONCLUSION: The osimertinib and anti-PD-L1 combined treatment group had the highest inflammation scores in pathologic grades of H&E staining of lung tissue and had the highest percentages of myeloperoxidase positive cells. However, combining gefitinib and anti-PD-L1 treatment appeared to not increase the level of pneumonitis in mice. Total cell counts, neutrophil counts and total protein concentration in BALFs were also significantly increased in the osimertinib and anti-PD-L1 combined treatment group. We next evaluated proinflammatory factors in BALFs. The levels of IFN-γ, IL-2, IL-5, TNF-α and IL-12p70 were increased in osimertinib and anti-PD-L1 combined treatment group. Comparison of different sequences of drug administration demonstrated that mice treated with osimertinib followed by PD-L1 antibody did not show evident lung inflammation. Our findings indicate that osimertinib, rather than gefitinib combined with anti-PD-L1 treatment could lead to lung injury in an EGFR mutated tumor-bearing mouse model. The sequence and timing of combining EGFR-TKI and PD-L1 antibody may influence the severity of pneumonitis.

Impact of serum vascular endothelial growth factor and interleukin-6 on treatment response to epidermal growth factor receptor tyrosine kinase inhibitors in patients with non-small-cell lung cancer.

BACKGROUND: Although EGFR-tyrosine kinase inhibitors (EGFR-TKIs) are the standard treatment for patients with EGFR-mutant non-small-cell lung cancer (NSCLC), responses vary within individuals. The current study aimed to investigate whether serum levels of several cytokines and their dynamic changes during TKI treatment could be used to predict the efficacy of EGFR-TKIs. MATERIALS AND METHODS: Pre-treatment and one-month post-treatment serum levels of hepatocyte growth factor (HGF), interleukin-10 (IL-10), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), interferon gamma (IFN-γ) and monocyte chemotactic protein-1 (MCP-1) were measured using enzyme-linked immunosorbent assay and U-plex biomarker group assays in patients with EGFR-mutant NSCLC received first-line EGFR-TKIs. RESULTS: Patients who had lower baseline serum levels of IL-6 had better object response rate (ORR) than those with high levels (74.2% vs 42.9%, p = 0.014). PFS was significantly longer in patients with low baseline level of IL-6 (19.57 vs. 13.73 months, p = 0.003) and in those with reduced serum VEGF and HGF levels after treatment (20.30 vs. 14.33 months, p = 0.009; 22.77 vs. 14.33 months, p = 0.002; respectively). Multivariate analyses showed that lower baseline serum IL-6 level was significantly associated with longer PFS (HR = 0.469, p = 0.022) and OS (HR = 0.181, p = 0.004). Reduction of serum VEGF and HGF levels after treatment was associated with significantly longer PFS (HR = 0.447, p = 0.017; HR = 0.365, p = 0.003; respectively). Lower pre-treatment serum VEGF level was associated with dramatically longer OS (HR = 0.277, p = 0.018). CONCLUSIONS: Our study suggested that serum levels of HGF, IL-6 and VEGF and its dynamic change during TKI treatment could be used to predict the efficacy of EGFR-TKIs treatment in patients with EGFR-mutant NSCLC.

Worldwide Research Productivity in the Field of Minimally Invasive Spine Surgery: A 20-year Survey of Publication Activities.

MINI: The time trend for the number of minimally invasive spine surgery articles showed a significant increase over time with an average of 93.23 articles per year. Among all related journals, Spine published the largest number of articles in minimally invasive spine surgery research and was the most popular one in the top five countries. STUDY DESIGN: Bibliometric analysis. OBJECTIVE: This study aimed to reveal the characteristics of world productivity in the field of minimally invasive spine surgery (MISS) research and to provide a general picture for surgeons and researchers. SUMMARY OF BACKGROUND DATA: Significant growth has been observed in the field of MISS research in recent years. However, bibliometric studies concerning the quantity and quality of articles published in MISS journals are scarce. METHODS: All the data concerning MISS in this study originate from the Web of Science (Thomson Reuters, New York, NY) without restrictions. All selected literates were evaluated in the following aspects: publication year, publication journals, author, times cited, Web of Science category, countries/territories. RESULTS: A total number of 2051 articles were published worldwide. The articles published during 2000 to 2015 are more than 11.28 times when compared to those published before 2000. The United States published the largest number of articles (855/2051, 41.7%), followed by Germany (245/2051, 11.9%), South Korea (160/2051, 7.8%), China (147/2051, 7.2%), and Japan (108/2051, 5.2%) and had the highest total citations (16,626). Additionally, the United States had the highest average citations per article (12.14), followed by Japan (11.98), Germany (11.19), South Korea (11.04), and China (10.95). High-income countries published 98.73% of articles, upper-middle-income countries published 0.24% of articles, and middle-income countries published 1.03% of articles. CONCLUSION: The time trend for the number of MISS articles showed a significant increase over time with an average of 93.23 articles per year. The United States was the most productive country and had the highest average citations per article. Among related journals, Spine published the largest number of articles in MISS research and was the most popular one in the top five countries. LEVEL OF EVIDENCE: 5.