Programmed Death-ligand 1 Expression Research Articles

PD-L1 expression as a potential predictor of immune checkpoint inhibitor efficacy and survival in patients with recurrent or metastatic nasopharyngeal cancer: a systematic review and meta-analysis of prospective trials.

The predictive value of programmed death-ligand 1 (PD-L1) expression in nasopharyngeal cancer (NPC) patients receiving immune checkpoint inhibitors (ICIs) remains controversial. This study aimed to evaluate the optimal threshold of PD-L1 expression in predicting the efficacy of ICIs in patients with recurrent or metastatic (R/M) NPC. A meta-analysis was performed by retrieving relevant literature from PubMed, EMBASE, and Cochrane Library databases. Data on the pooled risk ratio (RR), mean overall survival (OS), progression-free survival (PFS), overall response rate (ORR) with 95% confidence interval, and 1%, 10%, and 25% PD-L1 expression cutoff points were obtained to examine the role of PD-L1 as a biomarker in R/M NPC patients receiving immunotherapy. In total, 1,312 patients from 14 studies were included. An improvement in PFS was observed in both patients with PD-L1 ≥ 1% (RR = 0.76, 95% CI 0.62-0.92, P = 0.005) and those with PD-L1 < 1% (RR = 0.68, 95% CI: 0.35-1.32, P = 0.26) who received first-line treatment with immunotherapy, with no significant difference between these subgroups. The pooled ORR was significantly higher in patients with PD-L1 ≥ 1% (ORR = 0.37) than in those with PD-L1 < 1% (ORR = 0.22) (P < 0.01) undergoing subsequent-line treatment. However, when we used the PD-L1 cutoff values of 10% and 25%, there was no significant difference between the positive (PD-L1 expression ≥ the cutoff value) and negative (PD-L1 expression < the cutoff value) subgroups. PD-L1 ≥ 1% also tended to be associated with better PFS and OS. Our meta-analysis suggested that first-line immunotherapy could significantly improve PFS in R/M NPC patients, regardless of the PD-L1 expression levels. Positive PD-L1 expression (≥ 1%) might be a potential predictive biomarker for a better overall response to immunotherapy in R/M NPC patients in subsequent-line setting. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024495841 PROSPERO, identifier CRD42024495841.

Impact of PD-L1 Expression on the Overall Survival of Caucasian Patients with Advanced EGFR-Mutant NSCLC Treated with Frontline Osimertinib.

The treatment of advanced non-small cell lung cancer (NSCLC) harboring an oncogenic epidermal growth factor receptor mutation (EGFRm) is currently based on osimertinib, a third-generation tyrosine kinase inhibitor (TKI). High Programmed death ligand 1 (PD-L1) expression ≥ 50% demonstrated to be a negative prognostic factor, mostly among Asian populations treated with 1st/2nd generation TKI. We investigated the impact of PD-L1 expression on the progression free survival (PFS) and overall survival (OS) within a cohort of patients receiving osimertinib as first-line treatment. Our bi-centre French retrospective study included all newly diagnosed patients with an advanced EGFRm (common and uncommon) NSCLC, between May 2018 and November 2022, treated with osimertinib. The primary endpoint was OS according to tumor proportion score PD-L1 expression (low/intermediate < 50% vs high ≥ 50%). Survival analyses were performed using Kaplan-Meier method and Cox model for adjusted multivariate analysis. Of 96 patients, median age was 71 (IQR 62-76), 70 were women (72.9%), 81 had a performance status (PS) 0-1 (84.3%). Median follow-up was 22.6 months (95% CI 20.5-24.7). Twenty patients (20.8%) had high PD-L1 expression ≥ 50%. No significant differences in baseline characteristics were observed based on PD-L1 status. Patients with PD-L1 ≥ 50% had significant shorter PFS and OS than those with PD-L1 < 50%, respectively 9.3 vs 17.5 months (p = 0.044 months) and 14.3 vs 26.0 months (p = 0.025). Multivariable adjustment for baseline characteristics found that PS ≥ 2 (HR 2.79, 95% CI 1.12-6.93, p = 0.027), PD-L1 ≥ 50% (HR 2.61, 95% CI 1.31 to 5.22, p = 0.007) and uncommon EGFR mutation (HR 4.59, 95% CI 1.95-10.80, p = <0.001) were associated with a shorter OS. Brain metastases at diagnosis and age ≥ 65 were not, respectively HR 1.66 (95% CI 0.90-3.06, p = 0.11) and HR 0.95 (95% CI 0.50-1.80, p=0.9). Our study found that PD-L1 expression ≥ 50% was associated with a shorter OS in EGFRm NSCLC patients treated with first line osimertinib. Further research is warranted to understand the underlying molecular and cellular mechanisms of this correlation.

FAT10 induces immune suppression by upregulating PD-L1 expression in hepatocellular carcinoma.

The upregulation of programmed death ligand 1 (PD-L1) plays a crucial role in facilitating cancer cells to evade immune surveillance through immunosuppression. However, the precise regulatory mechanisms of PD-L1 in hepatocellular carcinoma (HCC) remain undefined. The correlation between PD-L1 and ubiquitin-like molecules (UBLs) was studied using sequencing data from 20 HCC patients in our center, combined with TCGA data. Specifically, the association between FAT10 and PD-L1 was further validated at both the protein and mRNA levels in HCC tissues from our center. Subsequently, the effect of FAT10 on tumor progression and immune suppression was examined through both in vivo and in vitro experiments. Utilizing sequencing data, qPCR, and Western blotting assays, we confirmed that FAT10 was highly expressed in HCC tissues and positively correlated with PD-L1 expression. Additionally, in vitro experiments demonstrated that the overexpression of FAT10 fostered the proliferation, migration, and invasion of HCC cells. Furthermore, the overexpression of FAT10 in HCC cells led to an increase in PD-L1 expression, resulting in the inhibition of T cell proliferation and the enhancement of HCC cell resistance to T cell-mediated cytotoxicity. Moreover, in vivo experiments utilizing the C57BL/6 mouse model revealed that overexpression of FAT10 effectively suppressed the infiltration of CD8 + GZMB + and CD8 + Ki67 + T cells, as well as reduced serum levels of TNF-α and IFN-γ. Mechanistically, we further identified that FAT10 upregulates PD-L1 expression via activating the PI3K/AKT/mTOR pathway, but not in a ubiquitin-like modification. In conclusion, our findings indicate that FAT10 promotes immune evasion of HCC via upregulating PD-L1 expression, suggesting its potential as a novel target to enhance the efficiency of immunotherapy in HCC.

Effect of strong programmed cell death ligand-1 (PD-L1) expressions on clinical outcomes in advanced non-small cell lung cancer treated with third-generation epidermal growth factor receptor-tyrosine kinase inhibitors.

e20500 Background: Third-generation tyrosine kinase inhibitors (TKIs) are the standard treatment for advanced epidermal growth factor receptor (EGFR) mutation-positive lung adenocarcinoma. In first/second generation EGFR-TKIs, strong programmed death ligand 1 (PD-L1) expression contributes to primary resistance, significantly affecting patient prognosis. Despite this, the relationship between PD-L1 expression levels and third-generation TKIs remains unclear. Methods: This retrospective cohort study reviewed patients with advanced NSCLC who received third-generation EGFR-TKIs as first-line systemic therapy at the Shandong Cancer Hospital between March 2019 and June 2022. The EGFR status of the patients was assessed using amplification refractory mutation system fluorescence quantitative polymerase chain reaction, and the PD-L1 expression level was evaluated using Dako 22 C3 immunohistochemical staining. The Kaplan–Meier method was used for survival analysis. The log-rank test was used to compare differences in survival curves between the two groups. Results: Overall, 150 patients were included in this study. PD-L1 expression was negative (PD-L1 tumor proportion score &lt; 1%) in 89 cases, weak (1–49%) in 42 cases, and strong (≥50%) in 19 cases. The median follow-up period for the entire cohort was 22.12 months (median progression-free survival [mPFS]: 24.33 months); the median overall survival was not reached. mPFS for patients with negative, weak, and strong PD-L1 expressions was 23.60, 26.12, and 16.60 months, respectively. The mPFS for strong PD-L1 expression was significantly shorter than that for with weak PD-L1 expression but was not associated with negativity, particularly in the 19DEL and 21L858R subgroups. PFS was significantly shorter in patients with strong PD-L1 expression in both subgroups (19DEL and 21L858R) than in those with weak PD-L1 expression. Conclusions: Strong PD-L1 expression in tumor cells influenced the clinical outcomes of patients with advanced NSCLC treated with third-generation EGFR-TKIs. Stronger PD-L1 expression in TKI-treated patients with advanced first-line EGFR-mutated NSCLC was associated with worse PFS.

Circulating tumor cells enumeration and characterization in patients with lung cancer treated with immunotherapy.

e15030 Background: Programmed death-ligand 1 (PD-L1) is a predictive biomarker for immunotherapy in the treatment of non-small cell lung cancer (NSCLC). Assessing PD-L1 expression from the tumor specimen can be challenging because of tissue accessibility, heterogeneity, and dynamic changes in PD-L1 expression that may impact the status of PD-L1 during disease evolution and treatment. Hence, assessing PD-L1 status from archival tumor might not reflect its actual state on the tumor and having a real-time assessment of its expression with the use of non-invasive techniques such circulating tumor cells (CTCs) is useful. Methods: We conducted a single centre prospective study to detect CTCs in the blood of patients with stage III-IV NSCLC treated with immunotherapy using the standard CellSearch technology for CTC enumeration and the Epic Sciences technology for CTCs enumeration and assessment of PD-L1 protein expression on CTCs. CTCs were detected at baseline before treatment initiation and after 2 cycles of treatment. Study endpoints included CTCs detection and concordance between the 2 technologies, PD-L1 expression assessment on CTCs with the Epic Sciences technology, and concordance with tissue-based expression. Comparisons were made using Pearson correlation coefficient (PCC) and intraclass correlation coefficient (ICC) for count data and percentage of perfect agreement. Results: Between 2019 and 2022, 48 patients treated with immunotherapy were enrolled in the study. The mean ± standard deviation (SD) age was 66.8 ± 10.3 years, 63% were females, 42% received combination chemotherapy and immunotherapy, and 44% had adenocarcinoma histology. The tissue PD-L1 expression was high (≥50%), intermediate (1-49%), and low (&lt;1%) in 36%, 31% and 33% of patients respectively. The mean ± SD baseline CTCs count per 7.5ml was 1.97 ± 4 with CellSearch and 1.38 ± 2.72 per ml with Epic Sciences. After 2 treatment cycles, 22% and 41% of patients had an increase in their CTCs count with CellSearch and Epic Sciences, respectively and 30% and 29% had a decrease in their CTCs. The PCC and ICC for baseline CTCs detected by CellSearch and Epic Sciences were 0.72 and 0.61, respectively and for CTCs detected after 2 cycles of treatment by the 2 technologies were -0.16 and 0.45 respectively. One patient had PD-L1 expression on their CTCs with the Epic Sciences technology and there was no association between the PD-L1 expression on CTCs and on matched tissue samples. Conclusions: This study showed a moderate to strong correlation between the 2 technologies for baseline CTCs detection and moderate to poor correlation for CTCs detection after 2 cycles of therapy. No association was found between CTCs and tissue PD-L1 expression. Future work needs to further investigate the role of PD-L1 expression on CTCs.

Measure of minimal residual burden on circulating tumor cells with over-expression of programmed death-ligand 1 as a dynamic biomarker in patients with colorectal cancer.

e14553 Background: In stage III colorectal cancer (CRC) patients, the extent of oxaliplatin-combination as an adjuvant therapy is still undetermined. Approx. 25-50% Stage II-III CRC patients are known to develop recurrence and metastasis even after comprehensive treatment, attributed to occult disease and Minimal Residual Disease (MRD). Circulating Tumor Cells (CTCs) are bio-mechanistic extravasation source for micro-metastatic disease. CRC patients, with lower adjuvant therapy from 3 to 6 months are known to exhibit increased CTCs and positivity rate due to the emergence of resistant clones. Assays to detect CTCs and expression of Programmed Cell Death-Ligand 1 (PD-L1) as a dynamic biomarker simultaneously has wide clinical implications. Especially, when the tissue biopsy is not inadequate to detect molecular targets for immune checkpoint inhibitor (ICT) therapy. Methods: Retrospectively, 182 CRC cancer patients were analyzed for the presence of CTC and distribution at baseline and follow-ups (up to 0-4 follow ups). The peripheral blood 1.5 ml was analyzed using the OncoDiscover platform approved by CDSCO, India consisting multifunctional magneto-nanosystem mediated by anti-epithelial cellular adhesion molecule (EpCAM) antibody. CTCs were analyzed in patients with early stages- pre and post treatment, progressive disease, Disease Free Status (DFS) and in metastasis. The isolated cells were immune-stained to detect CK-18 +ve, CD45 -ve, DAPI +ve and PD-L1 +ve expression. PD-L1 expression in CTCs was validated by analyzing the linear intensity gradients of the fluorescence signals. CTCs were termed as PD-L1 -ve based on a weak or no detectable fluorescence signal and termed +ve based on a high fluorescence signal using automated image acquisition Zeiss microscope. Results: In a cohort of 182 CRC patient samples, n = 128 (70.3 %) showed the presence of CTCs. The fluorescence intensity for PD-L1 expression as a robust functional assay on CTCs for molecular characterization was developed. The distribution of CTCs ranged from 1-9. The mean fluorescence intensity value and cut-off for the expression of PD-L1 in CTCs was accounted to be ~1.02. Interestingly, in n = 54 (42.2 %) patients, CTCs showed positive expression of PD-L1. CTC +ve patients with PD-L1 expression were associated at all stages and even in early stage, progressive disease, and metastasis. Patients without any CTCs n = 54 (29.7%) either had clinically stable disease or were in DFS with no radio-graphical image. Conclusions: The presence of PD-L1 over-expression on CTCs is a dynamic biomarker in blood, showing the progression of disease even in patients with DFS status. CTC enumeration and assessing the PD-L1 expression on CTCs could offer highly individualized treatment plans in CRC patients.

Concordance of PD-L1 combined positive score (CPS) analysis between primary gastric cancer and matched peritoneal metastasis.

e16068 Background: Peritoneum represents one of the most common metastatic sites of gastroesophageal adenocarcinoma (GEA) and is associated with poor prognosis. Programmed death-ligand 1 (PD-L1) expression is a recognized predictive biomarker of response to immune checkpoint inhibitors (ICIs) in the first-line setting. However, data from pivotal trials showed poorer clinical efficacy of ICIs in the sub-set of patients with peritoneal involvement, regardless of PD-L1 score magnitude. Here, we investigated the temporal and spatial heterogeneity of PD-L1 expression between primary tumor and matched peritoneal metastasis. Methods: PD-L1 expression according to CPS was determined by immunohistochemistry using VENTANA PD-L1 (SP263) assays on formalin-fixed paraffin-embedded (FFPE) tumor tissues derived from 22 patients treated at our institution for advanced GEA from September 2015 to August 2023. Concordance rate of PD-L1 expression between primary tumor and matched peritoneal metastasis using PD-L1 CPS cut-off of 1 and 5 was reported (spatial heterogeneity); additionally, concordance between PD-L1 value before and after the administration of systemic treatments was analyzed (temporal heterogeneity). Results: 12(54.5%)/5(22.7%) primary tumor samples and 12(54.5%)/1(4.5%) peritoneal metastases showed PD-L1 CPS ≥ 1/ ≥ 5, respectively. Concordance of PD-L1 CPS between primary and peritoneal specimens was 54.5% and 72.7% according to CPS cuts-off of 1 and 5, respectively, highlighting marked spatial heterogeneity. High concordance rate (94%) was reported between negative PD-L1 CPS primary tumor samples and matched peritoneal metastases, against the cut-off of CPS ≥ 5; in contrast, none of the positive primary tumor samples retained PD-L1 expression in the peritoneum. Evident temporal heterogeneity of PD-L1 expression was also observed, with 56% concordance against CPS ≥ 5 in the pre- versus post-treatment comparison. Conclusions: PD-L1 expression in GEA is characterized by spatial and temporal heterogeneity which is more prominent for lower CPS cut-offs values. This evidence could hamper its role as predictive biomarker for ICIs. The high intra-patient discordance rate of PD-L1 CPS expression between positive primary tumor samples and matched peritoneal metastases suggests that peritoneal specimens should not be recommended as the preferred source for PD-L1 assessment.

Multi-index comprehensive evaluation of the efficacy and response mechanism of immunotherapy in non-small cell lung cancer.

This research conducted multi-index comprehensive evaluations of the immunotherapeutic efficacy and response in non-small cell lung cancer (NSCLC). Forty-five patients with epidermal growth factor receptor (EGFR)/anaplastic lymphoma kinase (ALK) wild-type advanced NSCLC who received immunotherapy were included. Immunohistochemistry was adopted to detect the expression levels of programmed death ligand 1 (PD-L1) with X-ray cross-complementing protein 1 (XRCC1) and excision repair cross-complementing group 1 (ERCC1) proteins in tumor tissues. Flow cytometry was utilized to measure the levels of T-cell subsets in peripheral blood before and after treatment. PCR-RELP method was employed to evaluate XRCC1 and ERCC1 gene polymorphisms in peripheral blood. According to the treatment effect, patients evaluated as complete response (CR), partial response (PR), and stable disease (SD) were categorized into the immune response group, and patients evaluated as progressive disease (PD) were categorized into the immune unresponsive group. The correlation between PD-L1 protein expression, XRCC1 and ERCC1 protein expression, gene polymorphisms, T-cell subpopulation levels, and treatment efficacy was analyzed. The therapeutic efficacy of patients with positive PD-L1 expression was better than that of patients with negative PD-L1 expression (P < 0.05). After treatment, peripheral blood CD3+ and CD4+ cell levels and Thl/Th2 cell levels were higher and CD8+ T cells were lower in the immune response group than in the immune unresponsive group (P < 0.05). Among the patients in the immune response group, peripheral blood CD3+ and CD4+ cell levels were higher and CD8+ T cells were lower in patients with positive PD-L1 expression than in patients with negative PD-L1 expression (P < 0.05). In the XRCC1 gene, the proportion of patients in the immune response group carrying the Arg/Trp + Trp/Trp genotype was higher than that of patients in the immune unresponsive group (P < 0.05). In the ERCC1 gene, the proportion of patients in the immune response group carrying the C/T + T/T genotype was higher than that of patients in the immune unresponsive group (P < 0.05). The positive expression rates of XRCC1 and ERCC1 in patients in the immune unresponsive group were higher than those in the immune response group (P < 0.05). PD-L1 protein expression, XRCC1 and ERCC1 protein expression, and gene polymorphisms are associated with immunotherapy outcome in EGFR/ALK wild-type advanced NSCLC patients, and may be biological indicators for predicting immunotherapy outcome in EGFR/ALK wild-type advanced NSCLC patients.

Effect of circulating tumor cells (CTC) and CTC clusters with PD-L1 dynamic biomarker on cellular burden in patients with ovarian cancer.

e17566 Background: In the precision oncology era, monitoring response to the treatments using circulating blood-based biomarkers e.g. circulating tumor DNA (ctDNA) and Circulating Tumor Cells (CTCs) are being rapidly evaluated and established. The leading cause of ovarian cancer patient mortality is owing to the delayed diagnosis, inability of patient selection for targeted therapies, including the use of immune checkpoint blockade (ICB) agents. The treatment of ovarian cancer usually involves a combination of surgery and chemotherapy. However, post operative resection and therapy with curative intent often fails in accounting the Minimal Cellular Disease (MCD). The dissemination of Circulating Tumor Cells (CTC) remains a dogma of Minimal Residual Disease (MRD) that diffuse and cause micro-metastasis through their epithelial to mesenchymal transitions (EMT) and ‘bio-mechanistic activation’ in blood circulation. Simultaneous detection of over-expression of Programmed Cell Death-Ligand 1 (PD-L1) on CTCs as a dynamic biomarker may be expedient for assessing patients for immune checkpoint inhibitor (ICT) therapy. Methods: In retrospective analysis of real-world data, 75 ovarian cancer patient’s peripheral blood was analyzed for the presence of CTCs with and without the expression of PD-L1 and CTC clusters. CTC were positively detected using OncoDiscover platform approved by CDSCO in 1.5 ml peripheral blood. The platform is multifunctional magneto nanosystem mediated by anti-epithelial cellular adhesion molecule (EpCAM) antibody. CTCs were identified as positive if they were EpCAM +ve, CK+ve, PD-L1 +ve, DAPI +ve and CD45-ve. PD-L1 expression on the CTCs was analyzed based on the linear intensity gradients of the fluorescence signals using image acquisition on an automated Zeiss Microscope. Results: At baseline sample analysis, 86 % (n=65) of the patients showed ≥ 1CTCs per 1.5 ml of blood. The CTC distribution in this study ranged from 1-9 CTCs. Whereas, 46.15 % (n=30) patients with CTCs showed the expression of PD-L1. Noteworthy, the highest number of CTCs were observed ~ 26.7 % (n=23) in age group 41-50. Interestingly, 8 % (n=6) of total patients showed the presence of CTC clusters. The presence of CTCs with expression of PD-L1 and CTC clusters did not correlate with factors like staging, follow ups, metastasis, and DFS status. Conclusions: We observed presence of MCD and MRD in CRC patients, in spite of curative intent in ovarian cancers. Detection of CTCs, CTC clusters with over-expression of PD-L1- as a real time dynamic biomarker may be useful for assessing the patients for early metastasis, regression, and selecting patient suitable for immune checkpoint inhibitor (ICT) therapy when the tissue is inadequate or unavailable for better outcome.

Effect of circulating tumor cells in clinically stable patients on the conundrum of recurrence with cellular residual disease.

e15040 Background: Despite no evidence of disease by radiological imaging, up to 30% breast cancer cases are known to relapse after treatment with a curative intent. The presence of CTCs in stage I-II cancer patients signals the activation of extravasation and invasion process leading to micro-metastasis and may lead to poor outcome. CTCs in blood circulation at any stage of cancer indicate detectable Minimal Cellular Disease (MCD). Thus the longitudinal investigation of patients with such biomarker remains highly implicative to predict the recurrence, therapy escalations, and dose modifications. The expression of Program Death - Ligand 1 (PD-L1) on CTCs is a dynamic biomarker and they may escape the elimination by immune system, indicative of progression of metastatic signature. Methods: Retrospectively, ina cohort of 20 cancer patients (e.g. lung, colon-rectal, breast, stomach, etc.) who recently underwent treatment were investigated for the presence of CTCs using CDSCO approved OncoDiscover platform having multi-components conjugated with anti EpCam antibody on magnetic nanoparticles. All patients represented clinically stable disease from previous radiological findings. CTCs enumeration assay was performed using CD45, EpCAM+, and CK18 and over-expression of PD-L1 in1.5 ml of peripheral blood using automated motorized Zeiss fluorescence microscopy. Results: In spite of 'no radiological' findings with clinically stable disease, out of 20 selected patients, 75% (n=15) showed at least 1 CTC. While, 55% (n=11) patients were detected with 1 CTC, 5% patients (n=1) with 2 CTCs, and 15% patients (n=3) were identified with 3 CTCs. In addition, 50% (n=10) of patients demonstrated with PD-L1 expression on CTCs; 1 patient exhibited a CTC cluster. Conclusions: Patients showed CRD in spite of a stable disease, which is an indication of progression of localized disease transforming from primary to secondary. The longitudinal monitoring of patients for CTCs with PD-L1 expression may reveal ‘real time’ residual disease, progression, regression, and actual response to the treatment. CRD monitoring can improve the curative intent by improving PFS and OS in solid cancers.

A phase 2/3 study of fianlimab plus cemiplimab versus cemiplimab in patients with advanced non-small cell lung cancer with tumors expressing PD-L1 ≥50%.

TPS8663 Background: Fianlimab (anti–lymphocyte activation gene 3 [LAG-3]) and cemiplimab (anti–programmed cell death-1 [PD-1]) are high-affinity, fully human, IgG4 monoclonal antibodies. In patients (pts) with advanced non-small cell lung cancer (aNSCLC) and programmed cell death-ligand 1 (PD-L1) expression ≥50% with no actionable mutations, first-line cemiplimab monotherapy showed significantly prolonged overall survival (OS) and progression-free survival (PFS) versus chemotherapy, with a safety profile consistent with previous reports for cemiplimab monotherapy. Despite pts’ selection by PD-L1 expression, only ~50% of pts respond to PD-1 therapy, thus there is a need for immune-oncology combinations like anti–LAG-3 plus anti–PD-1 to potentially improve outcomes. Methods: This is a randomized, double-blind, Phase 2/3 study (NCT05785767) to evaluate fianlimab + cemiplimab versus cemiplimab monotherapy as first-line treatment in pts with aNSCLC and tumors expressing PD-L1 ≥50%. The study will be conducted globally at ~210 sites. Key inclusion criteria: ≥18 years old; histologically confirmed squamous or non-squamous stage IIIB/C (not candidates for surgical resection or definitive chemoradiation) or stage IV NSCLC (no prior systemic treatment for recurrent or metastatic NSCLC); PD-L1 expression in ≥50% of tumor cells; ≥1 radiographically measurable lesion per Response Evaluation Criteria in Solid Tumors v1.1; Eastern Cooperative Oncology Group performance status ≤1; adequate organ and bone marrow function. This study has Phase 2 and Phase 3 parts and is expected to enroll ~850 pts. Pts will be treated for up to 108 weeks. In Phase 2, 150 patients will be randomized 1:1:1 into three treatment arms (Q3W IV): Arm A, fianlimab high dose + cemiplimab 350 mg; Arm B, fianlimab low dose + cemiplimab 350 mg; Arm C, cemiplimab 350 mg + saline/dextrose placebo. Based on findings from Phase 2, the dose of fianlimab (low or high) will be selected for Phase 3. In Phase 3, 700 patients will be randomized 1:1 into either experimental Arm A or B, and comparator Arm C (cemiplimab + placebo). In Phase 2, the primary endpoint is objective response rate (ORR) per blinded independent central review (BICR). The secondary endpoints are safety, ORR per investigator assessment, disease control rate (DCR), time to tumor response (TTR), duration of response (DOR), PFS, OS, patient-reported outcomes, pharmacokinetics, and immunogenicity. In Phase 3, the primary endpoint is OS in patients receiving fianlimab + cemiplimab versus cemiplimab monotherapy. Secondary endpoints are safety, ORR, DCR, TTR, DOR, and PFS, per BICR and investigator assessment, patient-reported outcomes, pharmacokinetics, and immunogenicity. This study is open for enrollment along with a second study of fianlimab + cemiplimab + chemotherapy in aNSCLC. Clinical trial information: NCT05785767 .

PD-L1 regulates tumor proliferation and T-cell function in NF2-associated meningiomas.

Programmed death-ligand 1 (PD-L1) expression is an immune evasion mechanism that has been demonstrated in many tumors and is commonly associated with a poor prognosis. Over the years, anti-PD-L1 agents have gained attention as novel anticancer therapeutics that induce durable tumor regression in numerous malignancies. They may be a new treatment choice for neurofibromatosis type 2 (NF2) patients. The aims of this study were to detect the expression of PD-L1 in NF2-associated meningiomas, explore the effect of PD-L1 downregulation on tumor cell characteristics and T-cell functions, and investigate the possible pathways that regulate PD-L1 expression to further dissect the possible mechanism of immune suppression in NF2 tumors and to provide new treatment options for NF2 patients. PD-L1 is heterogeneously expressed in NF2-associated meningiomas. After PD-L1 knockdown in NF2-associated meningioma cells, tumor cell proliferation was significantly inhibited, and the apoptosis rate was elevated. When T cells were cocultured with siPD-L1-transfected NF2-associated meningioma cells, the expression of CD69 on both CD4+ and CD8+ T cells was partly reversed, and the capacity of CD8+ T cells to kill siPD-L1-transfected tumor cells was partly restored. Results also showed that the PI3K-AKT-mTOR pathway regulates PD-L1 expression, and the mTOR inhibitor rapamycin rapidly and persistently suppresses PD-L1 expression. Invivo experimental results suggested that anti-PD-L1 antibody may have a synergetic effect with the mTOR inhibitor in reducing tumor cell proliferation and that reduced PD-L1 expression could contribute to antitumor efficacy. Targeting PD-L1 could be helpful for restoring the function of tumor-infiltrating lymphocytes and inducing apoptosis to inhibit tumor proliferation in NF2-associated meningiomas. Dissecting the mechanisms of the PD-L1-driven tumorigenesis of NF2-associated meningioma will help to improve our understanding of the mechanisms underlying tumor progression and could facilitate further refinement of current therapies to improve the treatment of NF2 patients.

Programmed-cell death ligand 1 (PD-L1) expression in equine sarcoids and squamous cell carcinoma.

Sarcoids and squamous cell carcinomas (SCCs) are the most concerning equine oncological diseases. Both tumors are challenging to manage due to their invasive behavior and high prevalence of recurrences. Furthermore, SCCs have a propensity to metastasize. Programed cell-death ligand 1 (PD-L1) has been one of the main therapeutic targets for immunotherapy in various human tumors. PD-L1 research in equine tumors is scarce and more efforts are necessary to understand the potential of this biomarker as a therapeutical target. Evaluate the immunohistochemical expression of PD-L1 in equine sarcoids and SCC. Thirteen equine tumors (seven sarcoids and 6 SCCs) were tested by immunohistochemistry and evaluated semi quantitatively to assess the percentage of positive cells. None of the sarcoids presented PD-L1 expression. Regarding SCC, 2 tumors presented <10% of labeled cells; 2 tumors presented 10%-25% of labeled cells and 2 tumors presented 25%-50% of labeled cells. There were statistically significant differences between sarcoids and SCC regarding the expression of PD-L1. Our results point to the fact that PD-L1 could be a potential therapeutic target against SCC, and also encourage in-depth studies in this area, with larger sample sizes.

Association of PD-L1 Expression with Clinicopathologic Characters in Gastric Cancer: A Comprehensive Meta-analysis.

The expression level of programmed death ligand-1(PD-L1) in patients with gastric cancer is the key to determining the use of immune drugs. The relationship between PD-L1 expression level and clinical characteristics is worth exploring. By setting the search terms correlated to PD-L1 and gastric cancer, a nearly comprehensive search was carried out in four major databases, and the deadline for searching was September 1, 2022. The retrieved documents were further screened by strict inclusion and exclusion criteria after removing the duplication. Next, the quality of the included studies was evaluated with the Newcastle-Ottawa Scale (NOS) scale. Finally, the STATA15.1 software was used to process data and draw plots, and the odds ratios (ORs) were adopted to assess the pooled effect size. A total of 85 works of literature were included in this study through screening strictly, and detailed data were extracted after evaluating the quality of the literature. The process of analysis was conducted in the whole population, Asia-Africa population, European and American population, and Asian population with CPS≥1, amd all found that the expression of PD-L1 in gastric cancer was correlated with age, tumor size, EBV infection, Her-2 expression and microsatellite status. However, the subgroup of the region also found some differences in Asian and Western regions, which was interesting and worth studying further. The included research of this study did not have significant publish bias. After careful analysis, this study found that age (>60 years), tumor size (>5cm), EBV infection (+), Her-2 expression (+), microsatellite status (MSI), and mismatch repair status (dMMR) were risk factors for positive expression of PD-L1 in gastric cancer.

Multidimensional analysis of B7 homolog 3 (B7-H3) RNA expression in small-cell lung cancer (SCLC) molecular subtypes.

8088 Background: SCLC is an aggressive cancer with a poor prognosis. B7-H3, a transmembrane protein showing low expression in normal tissues but overexpression in SCLC and other tumors, is a promising target for antibody–drug conjugates. We performed a multidimensional analysis of B7-H3/ CD276 expression in SCLC molecular subtypes (SCLC-A, -N, -P, and -I) and its relationship with expression of other immune-related genes. Methods: Clinical and molecular data for a cohort of patients (pts) with SCLC were derived from a real-world database (Caris Life Sciences, Irving, TX, USA). Tumor RNA expression was used to assign the SCLC molecular subtype derived from non-negative matrix factorization. Programmed death ligand-1 (PD-L1) protein expression was assessed by immunohistochemistry (IHC; antibody 22c3; positive cut-off: tumor proportion score &gt;1%). Demographic, clinical, and molecular data were summarized by SCLC subtype or B7-H3 expression quartile (Q). Spearman’s r evaluated correlations between expression of B7-H3 and other immune-related genes/signatures. Results: The cohort included 1721 pts (52.5% female; 98.9% [434/439] smokers; median age, 67 years [range, 18–90+]). Across the subtypes, B7-H3 expression was high and remarkably consistent ( q&gt;0.05; Table). Other biomarker genes, including DLL3 (q&lt;0.05), had lower and more variable expression. Median (range) B7-H3 expression across all samples was 16.75 (0–68.2) transcripts per million (TPM). Across B7-H3 expression Qs, the proportion of PD-L1-positive pts by IHC was similar (Q1, 39.8%; Q2, 46.5%; Q3, 40.7%; Q4, 39.2%). Median (95% confidence interval) B7-H3 expression was similar between pts with prior immunotherapy ( n=24; 14.43 [11.64–21.17] TPM) and pts without ( n=208; 14.20 [13.00–15.91] TPM); treatment information was not available for the remaining samples in this cohort. B7-H3 expression was not strongly correlated with any other immune-related genes/signatures, although several had moderate correlation ( HAVCR2/ TIM3, r=0.59; PDCD1LG2/ PD-L2, r=0.56; M2 macrophages, r=0.56; CD86, r=0.56). Conclusions: In pts with SCLC, B7-H3 showed high and consistent expression across subgroups defined by molecular subtype or prior immunotherapy. The relative expression of B7-H3 was higher and less variable among molecular subtypes than for other key molecular targets in this tumor type, including DLL3. B7-H3 expression had limited association with PD-L1 expression, supporting a role as a distinct therapeutic target. [Table: see text]

Discrepancies in therapeutic indications for the same oncology drugs among FDA, EMA, and Brazilian agency.

e23035 Background: Divergent marketing approvals for oncology drugs among prominent agencies can prompt questions, especially when they are grounded in the same evidence. The aim of this study was to evaluate and compare the assessment and approval processes for novel products and indications by the FDA, EMA, and the Brazilian Health Regulatory Agency (ANVISA). Methods: Therapeutic indications for FDA-approved anticancer drugs from January 2019 to December 2023 were identified. Data, including approval dates, details on authorization procedures and evidence presented, were extracted from the databases of the FDA, EMA, and ANVISA. Only approvals for non-hematologic solid tumors were considered. All data were publicly available, and ethical approval was not required. No patient involvement occurred in this study. Results: Between 2019 and 2023, the FDA granted approval for 154 therapeutic indications for marketing authorization, resulting from 148 pivotal trials. The predominant cancer types during this period were non-small cell lung cancer (31 approvals [20.1%]). Most trials were in phase III (66.8%) and randomized (68.1%). Additionally, 41 (26.6%) received accelerated approvals, with 6 subsequently obtaining regular approvals. Among the therapies, 66 trials (42.8%) involved active comparators, while 53 (34.4%) and 35 (22.7%) were single-arm and placebo-controlled trials, respectively. Approximately half (74 [48%]) of the therapies were approved for metastatic first-line treatment, 54 (35%) for second-line treatment, and the rest for neoadjuvant and/or adjuvant treatment. Regarding endpoint characteristics supporting approval, the most prevalent was a combination of objective response rate (ORR) + duration of response (DoR) (38 [24.6%]), followed by progression-free survival (PFS) + overall survival (OS) (31 [20.1%]). When comparing the 154 FDA-approved indications, 50 (32.4%) were not approved by EMA, and 60 (38.9%) were not approved by ANVISA. Furthermore, in 33 cases (21.4%), there were disparities in clinical indications between the FDA and EMA, primarily related to the target population specification, with 10 cases (6.4%) attributed to programmed death ligand-1 (PD-L1) expression. Notably, in these instances, the FDA approved the drug regardless of PD-L1 expression, while the EMA required a percentage of cells with PD-L1 expression. In all these cases, ANVISA aligned with the FDA's assessment. Conclusions: Significant clinical disparities were identified in the outcomes of the approval process for oncology products among the FDA, EMA, and ANVISA. Additional efforts are needed to standardize decision-making across regulatory systems.

Envafolimab plus chemotherapy as neoadjuvant therapy for resectable esophageal squamous cell carcinoma (ESCC): A prospective, single-arm, phase II study.

e14633 Background: Currently, chemotherapy plus PD-1 inhibitor immunotherapy has become a promising option in the neoadjuvant setting of resectable ESCC, nevertheless, the PD-ligand 1 (PD-L1) blockade-based combination has rarely been investigated to date. Envafolimab is the first and only globally approved subcutaneous (SC) PD-L1 inhibitor, which has shown satisfactory efficacy and safety profile in tumors. This Simon’s two-stage, phase II study explored the safety and feasibility of SC administration of envafolimab as an alternative to intravenous (IV) administration of PD-1/PD-L1 inhibitors in the neoadjuvant therapy of resectable ESCC. Here, we reported the results of the stage 1. Methods: In this Simon’s two-stage, phase II study, patients initially treated with locally advanced and resectable (stage II-IVA) ESCC were enrolled and received envafolimab (300mg, SC, day 1), albumin-bound paclitaxel (130mg/m2, IV, days 1 and 8), and carboplatin (AUC = 5, day 1) every 3 weeks for 3 cycles. The primary endpoints were safety and pathological complete response (pCR). A Simon’s two-stage design was utilized with following assumptions. Target accrual was 13 patients in the first stage (If 3 or more patients had pCR in stage 1, study could continue in stage 2), total 34 patients were enrolled in the stage 2. Secondary endpoints were major pathological response (MPR). Safety was assessed by adverse events (AEs) and postoperative complications. Results: Between October 2022 and April 2023, 13 (81.3%) of 16 enrolled patients completed neoadjuvant therapy and underwent surgery. All 13 (100%) surgical patients underwent successful R0 resection; of whom, 8 (61.5%) achieved pCR and 9 (69.2%) achieved MPR, respectively. Downstaging occurred in 10 (76.9%) of 13 patients. pCR and MPR were identified to be associated with tumor downstaging but not with PD-L1 expression. CPS levels in MPR and pCR group were significantly higher than that in Non- MPR and Non-pCR group. Grade 3-4 treatment-related AEs (TRAEs) and immune-related AEs (IrAEs) occurred in 12.5% and 37.5% of 16 patients, respectively. 10 (76.9%) of 13 patients reported postoperative complications. No treatment-related surgical delay or death occurred. Conclusions: Envafolimab plus chemotherapy as neoadjuvant therapy demonstrated promising antitumor activity for resectable ESCC with high rates of pCR, MPR and R0 resection, as well as acceptable tolerability. Based on the encouraging efficacy of our regimen in the first stage, we will continue the enrollment of patients in stage 2. Keywords: Esophageal squamous cell carcinoma; Envafolimab; Neoadjuvant therapy; Chemotherapy Clinical trial information: NCT05552651 .

Mitochondrial metabolism blockade nanoadjuvant reversed immune-resistance microenvironment to sensitize albumin-bound paclitaxel-based chemo-immunotherapy

Currently, the efficacy of albumin-bound paclitaxel (PTX@Alb) is still limited due to the impaired PTX@Alb accumulation in tumors partly mediated by the dense collagen distribution. Meanwhile, acquired immune resistance always occurs due to the enhanced programmed cell death-ligand 1 (PD-L1) expression after PTX@Alb treatment, which then leads to immune tolerance. To fill these gaps, we newly revealed that tamoxifen (TAM), a clinically widely used adjuvant therapy for breast cancer with mitochondrial metabolism blockade capacity, could also be used as a novel effective PD-L1 and TGF-β dual-inhibitor via inducing the phosphorylation of adenosine 5ʹ-monophosphate-activated protein kinase (AMPK) protein. Following this, to obtain a more significant effect, TPP-TAM was prepared by conjugating mitochondria-targeted triphenylphosphine (TPP) with TAM, which then further self-assembled with albumin (Alb) to form TPP-TAM@Alb nanoparticles. By doing this, TPP-TAM@Alb nanoparticles effectively decreased the expression of collagen in vitro, which then led to the enhanced accumulation of PTX@Alb in 4T1 tumors. Besides, TPP-TAM@Alb also effectively decreased the expression of PD-L1 and TGF-β in tumors to better sensitize PTX@Alb-mediated chemo-immunotherapy by enhancing T cell infiltration. All in all, we newly put forward a novel mitochondrial metabolism blockade strategy to inhibit PTX@Alb-resistant tumors, further supporting its better clinical application.

The clinical application of circulating tumor cells (CTCs) for immunotherapy in advanced pancreatic cancer.

e14541 Background: Circulating tumor cell (CTCs) has the potential utility for screening, prognostic and predictive assessment, and offers the potential for personalized management. This trial aimed to evaluate the prognostic and predictive impact of programmed cell death ligand 1 (PD-L1) positive CTCs in patients with pancreatic ductal adenocarcinoma (PDAC). Methods: Twenty-three heavily treated advanced PDAC patients were randomized to receive camrelizumab combined with apatinib or capecitabine, or placebo plus capecitabine until disease progression or unacceptable toxicity, and peripheral blood CTCs samples were collected at baseline and after treatment. Forty-nine CTCs samples from 23 recruited advanced PDAC patients were detected by subtraction enrichment and immunostaining-FISH (SE-iFISH). PD-L1 expression level also was evaluated in tumor tissue samples by Immunohistochemistry (IHC). Investigator-assessed 6-month overall survival (OS) rate and 3-month progression-free survival (PFS) rate was evaluated. Results: The positive detection rate of CTCs in 23 PDAC patients was 95.7%. The cell sub-types of sizes of CTC analysis showed that 58.6% CTCs was the small CTCs (Diameter &lt; 5μm). CTCs karyotypes analysis exhibited that triploid small CTCs were the main karyotype (41.2%) in small CTC, and pentaploid large CTCs was the major karyotype (74.7%) in large CTCs. PD-L1+ CTCs were detected in 43.5% of PDAC patients. Tissue PD-L1 positive detection rate was 50% (CPS &gt; 1%) in available tissue samples(n=10). The presence of PD-L1+ CTCs cohort exhibited a significant increase in 6-month OS rate (80% versus 38.5%, P &lt; 0.05) and 3-month PFS rate (70% versus 23.1%, P &lt; 0.05) compared to PD-L1- CTCs cohort. Compared with the PD-L1- CTCs patients, the combination therapy camrelizumab markedly improved the 6-month OS rates (75% versus 50%) and 3-month PFS rate (62.5% versus 25%) in PD-L1+ CTC patients. Conclusions: PD-L1+ CTCs could be considered as a favorable prognostic marker in advanced PDAC. These results suggest that PD-L1+ CTCs might be used as a predictor of the efficacy of cancer immunotherapy in advanced PDAC, and provide a new monitoring method for the precise treatment of advanced PDAC. The expanding sample size test is now ongoing. Clinical trial information: ChiCTR1900024095 .

Hyaluronic acid hydrogel to modulate tumor cell clustering and programmed death ligand 1 signaling in cancer stem cells.

e14584 Background: The root of malignancy lies in the extracellular matrix (ECM) surrounding the stromal cells. Thus, current therapeutic targets manipulate abnormal tumor microenvironments (TME), which nourish cancer stem cells (CSC) and induce tumor cell clustering (TCC). Notably, despite the first line of clinical therapy with surgery and chemotherapy, uncontrolled self-renewal of CSCs, conversion of non-CSCs to CSCs, and TCC trigger cancer recurrence. The transmembrane glycoprotein CD44 is thought to be a potential master regulator in cancer recurrence as it interacts with hyaluronic acid (HA) in TME, expresses aberrantly on CSCs, induces TCC by homophilic interactions like Plakoglobin despite less understanding on their crosstalk, and promotes expression of pro-tumorigenic factor programmed death ligand 1 (PD-L1). Notably, CD44 is expressed in multiple isoforms, and splice isoform switching of CD44 dictates the properties of CSC, which still needs to be clarified. Hence, we aimed to characterize CSCs based on CD44 isoform expression, investigate the crosstalk between CD44 and Plakoglobin, and then design a novel injectable HA hydrogel that can disguise TME and suppress PD-L1 to combat cancer recurrence. Methods: To characterize CSCs, we prepared different scaffolds of HA of varied molecular weights and other ECM proteins, cultured cancer cells (MDA-MB-231, HeLa), and determined the expression of CD44 isoforms. We sorted CD44+/CD24- expressing CSC by flow cytometry. We implemented immunoprecipitation to detect the interaction between CD44 and Plakoglobin. We created a novel HA hydrogel composed of low and very high molecular weight HA, thiolated gelatin, and other components crosslinked with PEGDA. Using a torsional rheometer, we measured matrix stiffness. We assessed the cell proliferation efficiency of CSC by a colony-forming assay. Results: The study disclosed that CD44 isoforms expressed differently based on ECM properties. Matrix stiffness dictated CD44 isoform expression. We observed that CD44 interacted with Plakoglobin. CD44 ablation upregulated Plakoglobin significantly. Tumor suppressor p53 played a significant role in CD44-Plakoglobin crosstalk. We observed that the injectable hydrogel modulated CD44-Plakoglobin signaling and inhibited TCC, likely promoting anoikis. The hydrogel affected CD44 splicing and modified the activity of the CD44 intracellular domain, which interacts with PD-L1 and thus suppressed PD-L1 expression significantly in CSC. Conclusions: Currently, antibodies targeting PD-1/PD-L1 signaling have been clinically approved for various cancers. However, this regimen of treatment is expensive. We report a novel injectable hydrogel that can disguise TME, modulate CSCs and PD-L1, and may advance an alternative cost-effective avenue for cancer immunotherapy.