Efficacy and safety of PD-1 inhibitors plus chemotherapy with or without endostatin for stage IV lung squamous cancer: a retrospective study

Backgroud The study aimed to analyze the efficacy and safety of PD-1 inhibitors plus chemotherapy with or without endostatin for stage IV lung squamous cell carcinoma (LUSC). Methods A total of 219 patients with stage IV LUSC were included. 120 received PD-1 inhibitors plus chemotherapy with or without endostatin (IC ± A), of which 39 received endostatin (IC+A) and 81 did not receive endostatin (IC-A). 99 received chemotherapy with or without endostatin (C ± A). Endpoints included overall survival (OS), progression-free survival (PFS), adverse events (AEs), and immune-related adverse events (irAEs). Results The median PFS in the IC ± A group versus the C ± A group was 8 and 4 months (P < 0.001), and the median OS was 17 and 9 months (P < 0.001). There was no significant difference in any grade AEs between the IC ± A and C ± A groups (P > 0.05). The median PFS in the IC+A group versus the IC-A group was 11 and 7 months (P = 0.024), and the median OS was 34 and 15 months (P = 0.01). There was no significant difference between the IC+A group and the IC-A group for all grade AEs and irAEs (P > 0.05). The subgroup analysis showed that patients with LIPI = 0 had significant OS and PFS benefits in IC+A group, while for patients with LIPI = 1–2, there was no significant difference in OS and PFS benefits between the IC+A group and IC-A group. Conclusions PD-1 inhibitors plus chemotherapy with endostatin might be first-line treatment for patients with stage IV LUSC.


Introduction
Stage IV lung squamous cell carcinoma (LUSC) typically carries a poor prognosis (1,2).However, survival rates among LUSC patients have improved with the application of immune checkpoint inhibitors (ICIs), particularly PD-1 inhibitors.Consequent to data unearthed from several clinical studies, the combination of PD-1 inhibitors with chemotherapy has emerged as the standard first-line treatment for stage IV driver gene-negative LUSC (3)(4)(5)(6).While this combination enhances survival rates in patients with advanced LUSC, the emergence of drug resistance remains a critical concern, limiting the potential benefits (7,8).
Endostatin (recombinant human vascular endostatin), targeting the endothelial cells of tumor vasculature, inhibits neovascularization, thereby impeding nutrient supply to tumor cells and curbing their proliferation and metastasis (9).As an anti-angiogenic agent, endostatin influences the tumor immune microenvironment similarly to PD-1 inhibitors, providing a rationale for their concurrent use (9,10).A retrospective clinical study has demonstrated that the combination of ICIs with endostatin offers greater efficacy and safety than the combination of ICIs with chemotherapy in treating advanced non-small cell lung cancer (NSCLC) (11).Furthermore, Phase II clinical trials in the Lung-MAP S1800A study have shown that combining pembrolizumab with ramucirumab leads to improved efficacy and survival outcomes for patients with advanced LUSC (12).
Our research focuses on determining the potential of endostatin to enhance the efficacy of PD-1 inhibitors in conjunction with chemotherapy for treating stage IV LUSC.Given the insufficient clinical evidence to support the combined usage of PD-1 inhibitors, chemotherapy, and endostatin, our study is designed to evaluate the efficacy and safety of this treatment regimen.Specifically, we aim to elucidate endostatin's impact on the outcome and adverse effects when simultaneously administered with PD-1 inhibitors and chemotherapy in stage IV LUSC patients.

Patients
This retrospective study included patients diagnosed with stage IV LUSC at our hospital from 2018 to 2023 who were first-line received PD-1 inhibitor combined with chemotherapy or chemotherapy alone with or without endostatin therapy.Inclusion criteria: (1) pathological diagnosis was LUSC; (2) clinical stage was stage IV; (3) Eastern Cooperative Oncology Group Performance Status (ECOG PS) was 0-2.Exclusion criteria: (1) patients' age less 18 years or over 85 years; (2) patients with other primary malignancies; (3) lack of clinical hematological and imaging data.All patients were clinically staged using the 8th edition of the American Joint Committee on Cancer (AJCC) TNM staging system.According to the inclusion and exclusion criteria, 219 patients with stage IV LUSC were finally enrolled.

Data collections
Clinical data included baseline data before receiving anti-tumor therapy: gender, age, ECOG PS, smoking history, histological type, clinical stage, distant metastatic(brain, liver, bone), PD-L1 expression level, and Lung Immune Prognostic Index (LIPI).LIPI is based on the derived neutrophil to lymphocyte ratio (dNLR) and lactate dehydrogenase (LDH), dNLR = baseline neutrophil count/ (white blood cell-neutrophil count), and is calculated as 1 point for dNLR greater than 3 or LDH greater than normal.Patients are divided into two groups with good (0 points) and poor (1-2 points) prognosis (13, 14).Other relevant clinical data: anti-tumor drugs, chemotherapy cycle, survival events, treatment efficacy, AEs and irAEs.

Outcomes
Overall survival (OS) is defined as the time between the first treatment and death from any cause or the last follow-up.Progression-free survival (PFS) is the time from the first treatment to disease progression, death from any cause, or the last follow-up.Objective response rate (ORR) is defined as the proportion of patients who achieve complete response (CR) or partial response (PR).Disease control rate (DCR) is defined as the proportion of patients who achieve CR, PR, and stable disease (SD).RECIST1.1 solid tumor evaluation criteria were used for short-term efficacy evaluation.All patients were followed up until September 2023.

Statistical analysis
We used Pearson's chi-square test or Fisher's exact test to compare categorical variables.The Kaplan-Meier method was used to plot survival curves, and the log-rank test was used for differences between survival curves.Variables with a P value ≤ 0.05 in univariate Cox analysis were included in the multivariate Cox analysis.Multivariate Cox analysis was used to determine independent prognostic factors affecting OS and PFS.Therefore, a statistical result P value < 0.05 was considered statistically significant.All analyses were performed using SPSS 25.0 (IBM, Armonk, NY, USA) for all of the above statistical analyses.

Patient characteristics
A total of 219 patients with stage IV LUSC were enrolled in our study.The baseline characteristics are shown in Tables 1, 2. There were 120 patients in the IC ± A group and 99 patients in the C ± A group.There were 39 patients in the IC+A group and 81 patients in the IC-A group.The IC ± A group and the C ± A group, the IC+A group and the IC-A group were mostly male, ECOG PS 0-1, smoking history, stage IVA, no brain metastasis, no liver metastasis, no bone metastasis, and the chemotherapy cycle ≥ 4. Except for the PD-L1 expression status, there were no statistical differences in other baseline characteristics between the IC ± A group and the C ± A group.There was no statistical difference in baseline characteristics between the IC+A group and the IC-A group.
Thirty-nine patients in the IC+A group had PFS events in 33 (84.6%) and OS events in 20 (51.2%).Eighty-one patients in the IC-A group had PFS events in 72 (88.8%) and OS events in 56 (69.1%).The median OS was 34 (95% CI: 9.6-58.4)and 15 (95% CI: 13.1-16.9)3).There was no statistical difference in ORR and DCR between the IC+A group and the IC-A group.

Safety and adverse events
The adverse events in each group are shown in Tables 6, 7, and the chi-square test for adverse events in each group is shown in Table 8.There were 116 (96.6%) any grade AEs and 72 (60%) grade 3-4 AEs in the IC ± A group, while there were 93 (93.9%) any grade AEs and 59 (59.5%) grade 3-4 AEs in the IC-A group.There was no statistical difference in any grade AEs and grade 3-4 AEs between IC ± A and C ± A groups (P > 0.05).In addition, there were 38 (97.4%) and 78 (96.2%) any grade AEs, 24 (61.5%) and 48 (59.2%) grade 3-4 AEs, 14 (35.9%) and 25 (30.9%)any grade irAEs, and 4 (10.2%) and 8 (9.9%) grade 3-4 irAEs in the IC+A group and the IC-A group, respectively.No statistical differences were observed in all AEs, grade 3-4 AEs, any grade irAEs and grade 3-4 irAEs between IC + A and IC-A groups.

Discussion
In patients with early-stage LUSC, the combination of PD-1 inhibitors and chemotherapy markedly decreases recurrence rates and improves prognosis.Similarly, for patients with locally advanced unresectable LUSC, this combined therapeutic approach reduces the risk of metastasis and enhances prognosis.However, the majority of patients present with advanced-stage disease at diagnosis, and the median OS for those receiving first-line PD-1 inhibitors and chemotherapy is only 17.2 months (1-3).Endostatin, an antiangiogenic agent, has been demonstrated in preclinical studies to synergistically enhance the impact of PD-1 inhibitors on lung tumor suppression (15).However, clinical evidence is sparse regarding the additional survival benefits conferred by endostatin in patients with stage IV LUSC, who are also receiving PD-1 inhibitors and chemotherapy.Thus, our research represents the initial effort to substantiate the applicability of combining a PD-1 inhibitor with chemotherapy and endostatin for first-line treatment in this patient population.Our findings indicate that the median OS and PFS for this regimen were 34 months and 11 months, respectively.Overall, AEs and irAEs were within acceptable safety margins and manageable.These results imply that incorporating endostatin with PD-1 inhibitors and chemotherapy may offer a novel frirst-line therapeutic option for stage IV LUSC.
In advanced LUSC, the combination of PD-1 inhibitors with chemotherapy has become a standard approach in clinical settings.Data from several clinical trials have established that this combination therapy provides superior ORR, DCR, PFS, and OS compared with chemotherapy alone (3)(4)(5)(6).Our study aligns with  Kaplan-Meier estimates of OS (A) and PFS (B) in the IC+A and IC-A population; IC+A,PD-1 inhibitor plus chemotherapy with endostatin; IC-A,PD-1 inhibitor plus chemotherapy without endostatin; OS, overall survival; PFS, progression-free survival; Time, month.these findings, demonstrating that, regardless of PD-L1 expression levels, the incorporation of PD-1 inhibitors with chemotherapy confers a greater survival advantage in the first-line management of stage IV LUSC.Despite these improvements, the survival benefit of anti-PD-1 therapy in combination with chemotherapy remains modest for patients with stage IV LUSC.
In 1971, Judah Folkman pioneered the concept of tumor treatment by inhibiting angiogenesis, proposing the theory that tumor proliferation depends on the formation of new blood vessels to supply essential nutrients.He posited that interrupting the tumor's blood supply could effectively starve the tumor (16).As an angiogenesis inhibitor, endostatin has undergone extensive clinical trials, demonstrating its capacity to target neovascular endothelial cells and suppress tumor growth (17).Notably, one case study reported that the addition of endostatin to PD-1 inhibitors and chemotherapy yielded significant results in treating stage IV LUSC (18).Furthermore, the combination has been attributed with promising efficacy and acceptable safety in the primary treatment of advanced NSCLC (10,19).Consequently, our retrospective analysis scrutinized the efficacy and safety of PD-1 inhibition with chemotherapy, both with and without the addition of endostatin, in stage IV LUSC treatment.The addition of endostatin was found to markedly enhance OS and PFS in patients.Multivariate Cox regression analysis reinforced the view that endostatin's synergistic use constitutes an independent prognostic indicator for stage IV LUSC patients undergoing PD-1 inhibitor and chemotherapy treatment.These findings endorse the combination of PD-1 inhibitors, chemotherapy, and endostatin as an emergent first-line treatment modality for stage IV LUSC, meriting adoption in clinical practice.
It is unclear whether the combination of PD-1 inhibitors with chemotherapy and endostatin is effective for all stage IV LUSC patients.Our study conducted a subgroup stratification analysis and found that, in most subgroups-including male patients, smokers, those with an ECOG PS 0-1, stage IVA, and patients without liver, Subgroup analysis of the IC ± A group versus the C ± A group for OS (A) and PFS (B) based on baseline characteristics; IC ± A,PD-1 inhibitor plus chemotherapy with or without endostatin; C ± A, chemotherapy with or without endostatin; OS, overall survival; PFS, progression-free survival, LIPI, lung immune prognostic index.brain, or bone metastases-the OS and PFS were more favorable with the combined treatment of PD-1 inhibitors, chemotherapy, and endostatin than without endostatin.Interestingly, patients with a LIPI score of 0 showed a benefit from the combined treatment, whereas those with LIPI scores of 1-2 did not experience significant advantages from the addition of endostatin.LIPI is assessed on the basis of two hematologic markers, LDH and dNLR, which reflect the systemic immune response to cancer-related inflammation (13, 14, 20).High levels of LDH are associated with cancer cell invasion and metastasis, and patients who have high levels of LDH before immunotherapy have relatively short PFS and OS (21)(22)(23)(24).The dNLR reflects the body's neutrophil levels, which are associated with immunosuppression and promote cancer cell metastasis (25-27).

B A
Subgroup analysis of the IC+A group versus the IC-A group for OS (A) and PFS (B) based on baseline characteristics; IC+A,PD-1 inhibitor plus chemotherapy with endostatin; IC-A,PD-1 inhibitor plus chemotherapy without endostatin; OS, overall survival; PFS, progression-free survival, LIPI, lung immune prognostic index.An exploratory pooled analysis of data from 4914 metastatic nonsmall cell lung cancer patients from 11 randomized multinational clinical trials showed that LIPI is important for predicting the prognosis of patients with metastatic non-small cell lung cancer, and represents a different prognosis by its stratification, which is particularly significant in patients receiving ICIs therapy (14).Consequently, the LIPI score is a vital prognostic marker for immunotherapy and a significant guide for optimizing anti-PD-1 therapy with chemotherapy and endostatin in clinical practice.
Our study is subject to several limitations.Primarily, it is singlecentered and retrospective in nature, characterized by a limited sample size, and incomplete detection of PD-L1 expression levels across the study population is a notable deficiency.Moreover, the incidence of survival events was not ubiquitously observed within our cohort, necessitating extended follow-up to amass comprehensive data on survival and adverse events, which would enable a more precise

Conclusions
Endostatin, administered concomitantly with chemotherapy and PD-1 inhibitors, yield substantial benefits in OS and PFS and are associated with manageable adverse events.This combination therapy is anticipated to become the preferred initial treatment option for stage IV LUSC, particularly in patients presenting with a LIPI score of 0.

TABLE 1
Baseline characteristics of IC ± A and C ± A.

TABLE 2
Baseline characteristics of IC+A and IC-A.

TABLE 3
Evaluation of outcomes in 219 patients with Stage IV LUSC.

TABLE 4
Univariate and multivariate Cox analysis of OS in the IC±A group.

TABLE 5
Univariate and multivariate Cox analysis of PFS in the IC±A group.

TABLE 6
Adverse events in group IC±A and group C±A.

TABLE 7
Adverse events in group IC+A and group C-A.

TABLE 8
Chi-square test of adverse events in each group. of the combined efficacy and toxicity of PD-1 inhibitors and chemotherapy with endostatin.Consequently, to elucidate the therapeutic potential of this combination, prospective clinical trials with more extensive participant numbers are indispensable. evaluation