PD-L1 testing by immunohistochemistry in immuno-oncology

Prognostic significance of combined PD-L1 expression in malignant and infiltrating cells in hepatocellular carcinoma treated with atezolizumab and bevacizumab

Background

Programmed death-ligand 1 (PD-L1) expression is abundant not only in malignant cells but also in infiltrating cells within the tumor microenvironment (TME) of hepatocellular carcinoma (HCC). This study explored the association between PD-L1 expression in TME and outcomes in HCC patients treated with atezolizumab plus bevacizumab (AB), emphasizing the implications of PD-L1 expression in both malignant and tumor-infiltrating cells.

Methods

This study included 72 patients with HCC who underwent percutaneous core needle liver biopsy before AB treatment between September 2020 and December 2023. PD-L1 expression on tumor tissues was assessed using the combined positive score (CPS) with cutoff values of 1 and 10, utilizing antibody clone 22C3 (Dako).

Results

The distribution of PD-L1 CPS included 24 patients with CPS <1, 33 patients with CPS 1-10, and 15 patients with CPS ≥10. Significant differences in overall survival (OS) were observed across the three groups, with CPS ≥10 showing the highest survival rates (p = 0.010). Patients with CPS ≥10 had better OS than those with CPS <10 (median OS 14.8 vs. 8.3 months, P = 0.046), and CPS ≥1 had better OS than CPS <1 (P = 0.021). For progression-free survival (mPFS), the CPS ≥10 group had the highest median PFS of 11.0 months among the three groups (P = 0.044). Objective response rates (ORR) were higher in the PD-L1 CPS ≥10 group than in the 1-10 and <1 group (53.3%, 27.3%, and 16.7%, respectively; P = .047). Multivariate analysis identified that PD-L1 expression ≥10 and ≥1 were associated with favorable outcomes regarding OS (hazard ratio [HR] 0.283, P = .027 and HR 0.303, P = .006, respectively).

Conclusions

Combined analysis of PD-L1 expression in malignant and tumor-infiltrating cells can be a promising biomarker for the prognosis of HCC patients treated with AB.

PD-L1 expression in testicular germ cell tumors undergoing spontaneous regression

Spontaneous regression of testicular germ cell tumors is a well-known phenomenon; however, the precise mechanisms of spontaneous regression are still unknown. Our study aimed to investigate programmed death-ligand 1 (PD-L1) expression in spontaneously regressed testicular germ cell tumors, exploring the link between the immune response and spontaneous regression. From a sample of 356 testicular germ cell tumors, we singled out 5 completely regressed and 6 partially regressed tumors. In four out of six cases with partial regression, a residual seminoma component was found, while in the remaining two cases, an embryonal carcinoma component was found. Comparisons were made with 20 pure seminomas and 20 mixed germ cell tumors (MGCTs). A semiquantitative immunohistochemical analysis of PD-L1 expression in tumor cells and intra/peritumoral lymphocytes was performed. There was no PD-L1 expression in tumors with complete regression. All partially regressed tumors showed expression in intra/peritumoral lymphocytes within the tumor remnants. Expression was significantly more frequent in pure seminomas compared to MGCTs (P = 0.004). A positive correlation was demonstrated between the seminoma component and the proportion of PD-L1 positive lymphocytes, with a Kendall's Tau-b coefficient of 0.626 (P < 0.001). Tumor cells showed PD-L1 expression in three MGCTs within the embryonal carcinoma component. Our results support an immunological mechanism of spontaneous tumor regression, with the strongest potential in testicular tumors containing seminoma components. However, further research is necessary to determine the role of PD-L1 ligand more precisely in the microenvironment of spontaneously regressed tumors.

Evaluation of PD-1 and interleukin-10-receptor expression by T lymphocytes in malignant and benign pleural effusions

PD-1 (programmed cell death protein-1)/PD-L1 (programmed cell death ligand 1) as well as IL-10 (interleukin-10)/IL-10R (interleukin-10 receptor) interactions play a major role in tumor immune evasion in various malignancies. Several studies investigated the expression of PD-1 on T lymphocytes in pleural effusions (PE) in patients with malignant diseases. However, results in malignant pleural effusions (MPE) compared to benign PE (BPE) are underreported. In this prospective study, 51 patients (median age 66 years, IQR 54-78, 47% male) with PE of malignant or benign origin at the Medical University of Vienna between March 2021 and November 2022 were enrolled and divided into three groups according to the cytological results (group 1: MPE [n = 24, 47%]; group 2: BPE in malignant disease [n = 22, 43%]; group 3: BPE in benign disease [n = 5, 10%]). In the cytological samples, T cells were analyzed for the expression of PD-1 and IL-10R via flow cytometry. In MPE, the proportion of PD-1+ T lymphocytes on CD4+ cells was significantly lower than in BPE (40.1 vs. 56.3 in group 1 vs. 3, p = 0.019). Moreover, a significantly lower expression of PD-1+ IL-10R+ CD8+ (9.6 vs. 35.2 in group 1 vs. 2, p = 0.016; 9.6 vs. 25.0 in group 1 vs. 3, p = 0.032) and a significantly higher expression of PD-1-IL-10R-CD8+ T lymphocytes (43.7 vs. 14.0 in group1 vs. 2, p = 0.045; 43.7 vs. 23.3 in group 1 vs. 3, p = 0.032) were observed in MPE when compared to BPE. The frequency of T cells expressing PD-1 and IL-10R on CD8+ T cells is significantly lower in MPE compared to BPE regardless of the underlying disease indicating a different microenvironment in PE driven by the presence of tumor cells. Our observation spotlights the possible involvement of PD-1 and IL-10R in MPE.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

PD-1/PD-L1 axis: implications in immune regulation, cancer progression, and translational applications

The PD-1/PD-L1 axis is a complex signaling pathway that has an important role in the immune system cells. Programmed cell death protein 1 (PD-1) acts as an immune checkpoint on the T lymphocytes, B lymphocytes, natural killer (NK), macrophages, dendritic cells (DCs), monocytes, and myeloid cells. Its ligand, the programmed cell death 1 ligand (PD-L1), is expressed in the surface of the antigen-presenting cells (APCs). The binding of both promotes the downregulation of the T cell response to ensure the activation to prevent the onset of chronic immune inflammation. This axis in the tumor microenvironment (TME) performs a crucial role in the tumor progression and the escape of the tumor by neutralizing the immune system, the engagement of PD-L1 with PD-1 in the T cell causes dysfunctions, neutralization, and exhaustion, providing the tumor mass production. This review will provide a comprehensive overview of the functions of the PD-1/PD-L1 system in immune function, cancer, and the potential therapeutic implications of the PD-1/PD-L1 pathway for cancer management.

Defining clinically useful biomarkers of immune checkpoint inhibitors in solid tumours

Although more than a decade has passed since the approval of immune checkpoint inhibitors (ICIs) for the treatment of melanoma and non-small-cell lung, breast and gastrointestinal cancers, many patients still show limited response. US Food and Drug Administration (FDA)-approved biomarkers include programmed cell death 1 ligand 1 (PDL1) expression, microsatellite status (that is, microsatellite instability-high (MSI-H)) and tumour mutational burden (TMB), but these have limited utility and/or lack standardized testing approaches for pan-cancer applications. Tissue-based analytes (such as tumour gene signatures, tumour antigen presentation or tumour microenvironment profiles) show a correlation with immune response, but equally, these demonstrate limited efficacy, as they represent a single time point and a single spatial assessment. Patient heterogeneity as well as inter- and intra-tumoural differences across different tissue sites and time points represent substantial challenges for static biomarkers. However, dynamic biomarkers such as longitudinal biopsies or novel, less-invasive markers such as blood-based biomarkers, radiomics and the gut microbiome show increasing potential for the dynamic identification of ICI response, and patient-tailored predictors identified through neoadjuvant trials or novel ex vivo tumour models can help to personalize treatment. In this Perspective, we critically assess the multiple new static, dynamic and patient-specific biomarkers, highlight the newest consortia and trial efforts, and provide recommendations for future clinical trials to make meaningful steps forwards in the field.

PD-L1 expression in squamous cervical carcinomas of Mozambican women living with or without HIV

Programmed death-ligand 1 (PD-L1) is overexpressed in squamous cervical cancer (SCC) and can be used for targeted immunotherapy. The highest mortality rates of SCC are reported in sub-Saharan Africa, where Human immunodeficiency virus (HIV) prevalence is high. In Mozambique most SCC patients present at advanced stages. Thus, there is a need to introduce new treatment options. However, immunocompromised patients were frequently excluded in previous clinical trials. Our aim was to determine if PD-L1 expression in SCC is as prevalent among women living with HIV (WLWH) as among other patients. 575 SCC from Maputo Central Hospital were included. HIV status was available in 266 (46%) cases PD-L1 expression was scored through tumour proportion score (TPS) and combined positive score (CPS). PD-L1 was positive in 20.1% of the cases (n = 110), TPS (score ≥ 25%) and in 26.3% (n = 144), CPS (score ≥ 1). Stratifying according to the HIV status, WLWH were TPS positive in 16.7%, compared to 20.9%, p = 0.43, and concerning CPS 21.1% versus 28.7%, p = 0.19, respectively. PD-L1 status was not influenced by stage, Ki-67 or p16, CD8 expression influenced only CPS status. Our data indicates that the documented effect of PD-L1 therapy on SCC should be confirmed in randomized clinical trials in an HIV endemic milieu.

Comprehensive molecular and clinical insights into non-small cell lung cancer transformation to small cell lung cancer with an illustrative case report

Histologic transformation to small cell lung cancer (tSCLC) is a rare but increasingly recognised mechanism of acquired resistance to tyrosine kinase inhibitors (TKI) in patients with epidermal growth factor receptor (EGFR)-positive non-small cell lung cancer (NSCLC). Beyond its acknowledged role in TKI resistance, histologic transformation to SCLC might be an important, yet under-recognised, mechanism of resistance in NSCLC treated with immunotherapy. Our review identified 32 studies that investigated tSCLC development in patients with EGFR-mutated NSCLC treated with TKI therapy and 16 case reports of patients treated with immunotherapy. It revealed the rarity of tSCLC, with a predominance of EGFR exon 19 mutations and limited therapeutic options and outcomes. Across all analysed studies in EGFR-mutated NSCLC treated with TKI therapy, the median time to tSCLC development was ∼17 months, with a median overall survival of 10 months. Histologic transformation of EGFR-mutated NSCLC to SCLC is a rare, but challenging clinical problem with a poor prognosis. A small number of documented cases of tSCLC after immunotherapy highlight the need for rebiopsies at progression to diagnose this potential resistance mechanism. Further research is needed to better understand the mechanisms underlying this phenomenon and to develop more effective treatment strategies for patients with tSCLC.

STAT3 Expression and Its Correlation with PD-L1 Expression in Non-Hodgkin's Lymphoma and Hodgkin's Lymphoma at Dr. Saiful Anwar Regional Public Hospital in Malang, Indonesian Population

Background

Lymphomas are malignant lymphocyte neoplasms that globally account for 10% of cancers in individuals aged <20 years. Malignant lymphomas are divided into Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). Despite the availability of many therapeutic modalities for lymphoma, such as Brentuximab vedotin, Nivolumab, and Pembrolizumab, it is still necessary to identify appropriate strategies with minimal side effects. Immunotherapy is a promising approach, exemplified by targeting JAK/STAT3 signaling, which can inhibit tumor growth and enhance antitumor immune responses. Hence, STAT3 (signal transducer and activator of transcription 3) is a promising therapeutic target. PD-L1 (programmed death-ligand 1), an immune checkpoint molecule, is used as a frontline treatment for various cancers. This study aims to determine STAT3 expression and its correlation with PD-L1 expression in NHL and HL to serve as a basis for further research on anti-STAT3 and its combination with other therapy targets.

Methods

Samples were obtained from paraffin blocks of patients with confirmed diagnoses of NHL and HL, and then immunohistochemical staining was carried out with PD-L1 and STAT3 antibodies. The collected data were then analyzed using SPSS.

Results

Among the 10 HL patients, no patients (0%) expressed STAT3, while nine patients (90%) expressed PD-L1. Among the 10 NHL patients, 1 patient (10%) expressed STAT3, while six patients (60%) expressed PD-L1. There were no significant differences in STAT3 expression and PD-L1 expression between HL patients and NHL patients. There was no correlation between STAT3 and PD-L1 expression in HL and NHL because almost all STAT3 expressions were negative.

Conclusion

Although this study revealed no differences between STAT3 and PD-L1 expression in HL and NHL and no significant correlation between STAT3 and PD-L1 expression in HL and NHL, this may serve as the basis for understanding the role of STAT3 and PD-L1 in the regulation of HL and NHL, which may be useful for further research targeting STAT3 and PD-L1 immunotherapy in HL and NHL.

The future of cervical cancer prevention: advances in research and technology

This article provides an informative overview of the current situation and future trends in cervical cancer prevention. Cervical cancer remains a significant public health concern worldwide and is characterized by notable variations in both incidence and mortality rates between developed and developing countries. This underscores the importance of understanding the pathophysiology of cervical cancer, stressing the involvement of high-risk HPV types. The presence of supplementary risk factors facilitates the transition from infection to cancer. This review examines current preventive methods, including the success of HPV vaccines such as Gardasil and Cervarix, and the effectiveness of screening techniques, from cytology to HPV DNA testing. It noted the limitations faced by primary and secondary preventive measures, particularly in low-resource settings, which include access to vaccines and effective screening procedures. Emerging technologies in cervical cancer prevention, such as liquid-based cytology, molecular testing, and AI, promise to improve early detection and diagnosis accuracy and efficiency. The potential of precision medicine to customize treatment based on individual risk factors was discussed. It explores the innovation in genetic editing techniques, such as CRISPR/Cas9, in targeting HPV oncoproteins, the advent of immunotherapy, the role of tumor-infiltrating lymphocytes, and the prospects of biomarkers in improving early detection. Research and technological advancements are leading to transformative changes in cervical cancer prevention. These developments suggest a path toward improved screening, diagnosis, and treatment that could significantly reduce the global burden of the disease. However, realizing the full potential of these advances requires inclusive research and international collaboration to overcome access disparities, particularly in resource-limited settings.

The Role of Programmed Cell Death Ligand 1 Expression in Pituitary Tumours: Lessons from the Current Literature

BACKGROUND

Programmed cell death-1 (PD-1) and PD ligand-1 (PD-L1) expression predict the biological behaviour, aggressiveness, and response to immune checkpoint inhibitors in different cancers. We reviewed the published data on PD-L1 expression in pituitary tumours from the perspective of its biological role and prognostic usefulness.

SUMMARY

A literature review focused on PD-L1 expression in pituitary tumours was performed. Six immunohistochemistry-based studies which assessed PD-L1 positivity in pituitary tumours were included, encompassing 704 patients. The cohort consisted of 384 (54.5%) nonfunctioning tumours and 320 (43.5%) functioning pituitary tumours. PD-L1 expression was positive in 248 cases (35.2%). PD-L1 positivity rate was higher in functioning than in nonfunctioning tumours (46.3% vs. 26.0%; p < 0.001) but also higher in growth hormone-secreting tumours (56.7%) and prolactinomas (53.6%) than in thyrotroph (33.3%) or corticotroph tumours (20.6%). While proliferative pituitary tumours showed higher rate of PD-L1 positivity than non-proliferative tumours (p < 0.001), no association with invasion or recurrence was found.

KEY MESSAGES

PD-L1 is expressed in a substantial number of pituitary tumours, predominantly in the functioning ones. PD-L1 positivity rates were significantly higher in proliferative pituitary tumours in comparison to non-proliferative tumours, but no differences were found concerning invasive or recurrent pituitary tumours. More studies following homogeneous and standardised methodologies are needed to fully elucidate the role and usefulness of PD-L1 expression in pituitary tumours.

Tumor microenvironment and clinical efficacy of first line immunotherapy-based combinations in metastatic renal cell carcinoma

The impact of tumor microenvironment (TME) in influencing clinical response to first-line immune checkpoint inhibitor (ICI)-based treatment in advanced renal cell carcinoma (RCC) is unclear. Immunohistochemistry (IHC) could identify biomarkers related to immune checkpoints and immune cell population. This study retrospectively characterized TME from 28 RCC patients who received first line ICI-based therapy through IHC assessment of selected markers and explored preliminary evidence about their possible correlation with treatment efficacy. We found a significantly higher count of CD80+, CD163+ cells and their ratio in RCC with clear cell component compared to those without clear cell features; additionally, patients with metastatic disease at diagnosis were associated with higher expression of CD163+ cells, while higher count of CD4+ cells and CD4+/CD8+ ratio were found in RCC with sarcomatoid features. Patients achieving partial or complete response were associated with lower expression of CD163+ cells (median 28 vs 47; p = 0.049). Furthermore, lower expression of CD163+ was associated with better PFS (median PFS 20.0 vs 4.7 months; HR 0.22 p = 0.011) and OS (median OS NR vs 14.4 months; HR 0.28 p = 0.036). A longer OS was reported in PD-L1 CPS negative patients (median OS NR vs 11.8 months; HR 0.20 p = 0.024). High infiltration of CD163+ macrophages, who typically present "anti-inflammatory" M2-like phenotype, could identify a subgroup of patients with poor survival after receiving first-line ICI.

Predictive and Prognostic Biomarkers and Tumor Antigens for Targeted Therapy in Urothelial Carcinoma

Urothelial carcinoma (UC) is the fourth most prevalent cancer amongst males worldwide. While patients with non-muscle-invasive disease have a favorable prognosis, 25% of UC patients present with locally advanced disease which is associated with a 10-15% 5-year survival rate and poor overall prognosis. Muscle-invasive bladder cancer (MIBC) is associated with about 50% 5 year survival when treated by radical cystectomy or trimodality therapy; stage IV disease is associated with 10-15% 5 year survival. Current therapeutic modalities for MIBC include neoadjuvant chemotherapy, surgery and/or chemoradiation, although patients with relapsed or refractory disease have a poor prognosis. However, the rapid success of immuno-oncology in various hematologic and solid malignancies offers new targets with tremendous therapeutic potential in UC. Historically, there were no predictive biomarkers to guide the clinical management and treatment of UC, and biomarker development was an unmet need. However, recent and ongoing clinical trials have identified several promising tumor biomarkers that have the potential to serve as predictive or prognostic tools in UC. This review provides a comprehensive summary of emerging biomarkers and molecular tumor targets including programmed death ligand 1 (PD-L1), epidermal growth factor receptor (EGFR), human epidermal growth factor receptor 2 (HER2), fibroblast growth factor receptor (FGFR), DNA damage response and repair (DDR) mutations, poly (ADP-ribose) polymerase (PARP) expression and circulating tumor DNA (ctDNA), as well as their clinical utility in UC. We also evaluate recent advancements in precision oncology in UC, while illustrating limiting factors and challenges related to the clinical application of these biomarkers in clinical practice.

Progress of lymphocyte activation gene 3 and programmed cell death protein 1 antibodies for cancer treatment: A review

The application of immune checkpoint inhibitors has proven to be an effective treatment for cancer. Immune checkpoints such as programmed cell death protein 1/programmed cell death protein 1 ligand 1 (PD-1/PD-L1), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), T-cell immunoglobulin-3 (TIM-3), T-cell immunoglobulin and ITIM domain (TIGIT), and lymphocyte activation gene-3 (LAG-3) have received extensive attention, and the efficacy of antibodies or inhibitors against these checkpoints (either alone or in combination) has been evaluated in many tumors. This paper provides a brief overview of the PD-1 and LAG-3 checkpoints, and then shifts focus to the combined use of PD-1 and LAG-3 antibodies in both in vivo and in vitro experiments. In the in vitro experiments, we examined the correlation between the expression and activation of these inhibitors on T cells, and also assessed toxicity in animals in preparation for in vivo experiments. The effects of the combined use of PD-1 and LAG-3 antibodies were then summarized in animal models of melanoma, MC38 carcinoma, and other tumors. In clinical studies, the combined application of these antibodies was assessed in patients with melanoma, colorectal, breast, and renal cell cancers, as well as other solid tumors. In general, the combination of PD-1 and LAG-3 antibodies has shown promising results in both in vivo and in vitro studies.

Revisiting the impact of clinicopathologic characteristics in PD-L1 profile in a large cohort of non-small cell lung cancer

Background

Immunotherapies using anti-programmed cell death ligand-1 (PD-L1) agents have recently shown remarkable outcomes in patients with non-small cell lung cancer (NSCLC). However, there was a poor correlation between PD-L1 expression and treatment response. Many researchers have focused on the clinicopathological factors associated with prognosis, but the results are conflicting. In the present study, we investigated the clinicopathological significance of PD-L1 overexpression in NSCLC cells.

Methods

In total, 344 NSCLC cases with PD-L1 assays were retrospectively analyzed. PD-L1 expression was evaluated via immunohistochemical staining using antibodies against SP263 and SP142. The correlation between clinicopathological factors and PD-L1 expression was analyzed for various clinicopathological features.

Results

PD-L1 expression significantly correlated with several poor clinicopathological factors, including the solid component of adenocarcinoma, lymphatic invasion, and recurrence. Squamous cell carcinoma, older age, and male sex were also associated with PD-L1 expression. However, we could not observe correlation between PD-L1 expression and disease-free survival (DFS). A novel finding was that lower metastasis was associated with high PD-L1 expression of SP142 in tumor-infiltrating immune cells (ICs).

Conclusions

PD-L1 expression in NSCLC is associated with adverse clinicopathological features and recurrence; therefore, it could be utilized to predict poor prognosis. Furthermore, the high PD-L1 expression of SP142 in tumor-infiltrating ICs could be a potential marker for low metastasis.

MicroRNAs as regulators of immune checkpoints in cancer immunotherapy: targeting PD-1/PD-L1 and CTLA-4 pathways

Immunotherapy has revolutionized cancer treatment by harnessing the power of the immune system to eliminate tumors. Immune checkpoint inhibitors (ICIs) block negative regulatory signals that prevent T cells from attacking cancer cells. Two key ICIs target the PD-1/PD-L1 pathway, which includes programmed death-ligand 1 (PD-L1) and its receptor programmed death 1 (PD-1). Another ICI targets cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). While ICIs have demonstrated remarkable efficacy in various malignancies, only a subset of patients respond favorably. MicroRNAs (miRNAs), small non-coding RNAs that regulate gene expression, play a crucial role in modulating immune checkpoints, including PD-1/PD-L1 and CTLA-4. This review summarizes the latest advancements in immunotherapy, highlighting the therapeutic potential of targeting PD-1/PD-L1 and CTLA-4 immune checkpoints and the regulatory role of miRNAs in modulating these pathways. Consequently, understanding the complex interplay between miRNAs and immune checkpoints is essential for developing more effective and personalized immunotherapy strategies for cancer treatment.

PD-L1, STAT3, IL6, and EGFR Immunoexpressions in High-Grade Osteosarcoma

Introduction

Immunotherapy has been widely used in the treatment of various malignancies with satisfactory results. One of the agents for immunotherapy is an inhibitor of programmed cell death-1 and its ligands (PD-1 and PD-L1). However, attempts at utilizing PD-1/PD-L1 immunotherapy in osteosarcoma have not yielded favorable results. This may be due to differences in PD-L1 regulation and the immune landscape in osteosarcoma, as the mechanism is still poorly understood. Therefore, elucidating PD-L1 regulation in osteosarcoma is paramount in order to improve treatment results using immunotherapy.

Methods

This is a cross-sectional study conducted in the Department of Anatomical Pathology of Saiful Anwar Hospital using 33 paraffin blocks of confirmed cases of osteosarcoma. Immunohistochemical staining using PD-L1, STAT3, IL6, and EGFR was performed. Statistical analyses were subsequently performed on the immunoexpression data of these antibodies.

Results

PD-L1, STAT3, IL6, and EGFR expressions were found in 6 (18.2%), 6 (18.2%), 28 (84.8%), and 30 (90.9%) cases, respectively. There were significant correlations between PD-L1 and STAT3 (r = 0.620, p=<0.001), PD-L1 and EGFR (r = 0.449, p=0.009), as well as STAT3 and EGFR (r = 0.351, p=0.045).

Conclusion

The existence of a correlation between PD-L1, STAT3, and EGFR indicates the potential role of STAT3 and EGFR in PD-L1 regulation in osteosarcoma, which may become the basis for targeted therapy.

Establishment of Anti-Dog Programmed Cell Death Ligand 1 Monoclonal Antibodies for Immunohistochemistry

Immune checkpoint blockade therapy has shown successful clinical outcomes in multiple human cancers. In dogs, several types of tumors resemble human tumors in many respects. Therefore, several groups have developed the anti-dog programmed cell death ligand 1 (dPD-L1) monoclonal antibodies (mAbs) and showed efficacy in several canine tumors. To examine the abundance of dPD-L1 in canine tumors, anti-dPD-L1 diagnostic mAbs for immunohistochemistry are required. In this study, we immunized the peptide in the dPD-L1 intracellular domain, and established anti-dPD-L1 mAbs, L1Mab-352 (mouse IgG1, kappa), and L1Mab-354 (mouse IgG1, kappa). In enzyme-linked immunosorbent assay, L1Mab-352 and L1Mab-354 showed high-binding affinity to the dPD-L1 peptide, and the dissociation constants (KD) were determined as 6.9 × 10-10 M and 7.2 × 10-10 M, respectively. Furthermore, L1Mab-352 and L1Mab-354 were applicable for the detection of dPD-L1 in immunohistochemical analysis in paraffin-embedded dPD-L1-overexpressed cells. These results indicated that L1Mab-352 and L1Mab-354 are useful for detecting dPD-L1 in immunohistochemical analysis.

Refining PD-1/PD-L1 assessment for biomarker-guided immunotherapy: A review

Anti-programmed cell death ligand 1 (anti-PD-L1)  immunotherapy is an increasingly crucial in cancer treatment. To date, the Federal Drug Administration (FDA) has approved four PD-L1 immunohistochemistry (IHC) staining protocols, commercially available in the form of "kits", facilitating testing for PD-L1 expression. These kits comprise four PD-L1 antibodies on two separate IHC platforms, each utilizing distinct, non-interchangeable scoring systems. Several factors, including tumor heterogeneity and the size of the tissue specimens assessed, can lead to PD-L1 status misclassification, potentially hindering the initiation of therapy. Therefore, the development of more accurate predictive biomarkers to distinguish between responders and non-responders prior to anti-PD-1/PD-L1 therapy warrants further research. Achieving this goal necessitates refining sampling criteria, enhancing current methods of PD-L1 detection, and deepening our understanding of the impact of additional biomarkers. In this article, we review potential solutions to improve the predictive accuracy of PD-L1 assessment in order to more precisely anticipate patients' responses to anti-PD-1/PD-L1 therapy, monitor disease progression and predict clinical outcomes.

Triple-negative breast cancer: from none to multiple therapeutic targets in two decades

Triple-negative breast cancers (TNBCs) are more likely to occur in younger patients and have a poor prognosis. They are highly heterogeneous tumors consisting of different molecular subtypes. The only common characteristic among them is the absence of targets for endocrine therapy and human epidermal growth factor receptor 2 (HER2) blockade. In the past two decades, there has been an increased understanding of these tumors from a molecular perspective, leading to their stratification according to new therapeutic strategies. TNBC has ushered breast carcinomas into the era of immunotherapy. The higher frequency of germline BRCA mutations in these tumors enables targeting this repair defect by drugs like PARP inhibitors, resulting in synthetic lethality in neoplastic cells. Additionally, we have the identification of new molecules to which this generation of smart drugs, such as antibody-drug conjugates (ADCs), are directed. In this review, we will discuss the trajectory of this knowledge in a systematic manner, presenting the molecular bases, therapeutic possibilities, and biomarkers.

Comprehensive genomic profiling of a metastatic small cell lung carcinoma with a complete and long-term response to atezolizumab: A case report

Small cell lung cancer (SCLC) is a highly aggressive malignancy with a poor outcome. We present the case of a 57-year-old male patient with extensive-stage (ES-SCLC) treated with chemotherapy and atezolizumab. A complete response was achieved with a long remission of ∼three years. Comprehensive genomic profiling (CGP) of the tumor revealed high tumor mutation burden (13 mutations/Mb) and mutations of TP53, RB1 and ERCC4 genes. This case study confirms that a complete response to chemoimmunotherapy may be achieved in the case of ES-SCLC. It further provides the additional value of CGP and predictive testing in the management of ES-SCLC.