RICTOR amplification is associated with Rictor membrane staining and does not correlate with PD-L1 expression in lung squamous cell carcinoma.

RICTOR gene, which encodes the scaffold protein of mTORC2, can be amplified in various tumor types, including squamous cell carcinoma (SCC) of the lung. RICTOR amplification can lead to hyperactivation of mTORC2 and may serve as a targetable genetic alteration, including in lung SCC patients with no PD-L1 expression who are not expected to benefit from immune checkpoint inhibitor therapy. This study aimed to compare RICTOR amplification detected by fluorescence in situ hybridization (FISH) with Rictor and PD-L1 protein expression detected by immunohistochemistry (IHC) in SCC of the lung. The study was complemented by analysis of the publicly available Lung Squamous Cell Carcinoma (TCGA, Firehose legacy) dataset. RICTOR amplification was observed in 20% of our cases and 16% of the lung SCC cases of the TCGA dataset. Rictor and PD-L1 expression was seen in 74% and 44% of the cases, respectively. Rictor IHC showed two staining patterns: membrane staining (16% of the cases) and cytoplasmic staining (58% of the cases). Rictor membrane staining predicted RICTOR amplification as detected by FISH with high specificity (95%) and sensitivity (70%). We did not find any correlation between RICTOR amplification and PD-L1 expression; RICTOR amplification was detected in 18% and 26% of PD-L1 positive and negative cases, respectively. The TCGA dataset analysis showed similar results; RICTOR copy number correlated with Rictor mRNA and protein expression but showed no association with PD-L1 mRNA and protein expression. In conclusion, the correlation between RICTOR amplification and Rictor membrane staining suggests that the latter can potentially be used as a surrogate marker to identify lung SCC cases with RICTOR amplification. Since a significant proportion of PD-L1 negative SCC cases harbor RICTOR amplification, analyzing PD-L1 negative tumors by RICTOR FISH or Rictor IHC can help select patients who may benefit from mTORC2 inhibitor therapy.

Predicting effect of anti-PD-1/PD-L1 inhibitors therapy for hepatocellular carcinoma by detecting plasma metabolite based on UHPLC-MS.

Introduction: Anti-PD-1/PD-L1 inhibitors therapy has become a promising treatment for hepatocellular carcinoma (HCC), while the therapeutic efficacy varies significantly among effects for individual patients are significant difference. Unfortunately, specific predictive biomarkers indicating the degree of benefit for patients and thus guiding the selection of suitable candidates for immune therapy remain elusive.no specific predictive biomarkers are available indicating the degree of benefit for patients and thus screening the preferred population suitable for the immune therapy. Methods: Ultra-high-pressure liquid chromatography-mass spectrometry (UHPLC-MS) considered is an important method for analyzing biological samples, since it has the advantages of high rapid, high sensitivity, and high specificity. Ultra-high-pressure liquid chromatography-mass spectrometry (UHPLC-MS) has emerged as a pivotal method for analyzing biological samples due to its inherent advantages of rapidity, sensitivity, and specificity. In this study, potential metabolite biomarkers that can predict the therapeutic effect of HCC patients receiving immune therapy were identified by UHPLC-MS. Results: A partial least-squares discriminant analysis (PLS-DA) model was established using 14 glycerophospholipid metabolites mentioned above, and good prediction parameters (R2 = 0.823, Q2 = 0.615, prediction accuracy = 0.880 and p < 0.001) were obtained. The relative abundance of glycerophospholipid metabolite ions is closely related to the survival benefit of HCC patients who received immune therapy. Discussion: This study reveals that glycerophospholipid metabolites play a crucial role in predicting the efficacy of immune therapy for HCC.

Breaking Ground in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma: Novel Therapies Beyond PD-L1 Immunotherapy.

The treatment for recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) with immune checkpoint inhibitors (anti-PD1) with or without chemotherapy has led to an improvement in survival. Yet, despite this therapeutic advancement, only 15%-19% of patients remain alive at four years, highlighting the poor survival and unmet need for improved therapies for this patient population. Some of the key evolving novel therapeutics beyond anti-PD1 in R/M HNSCC have included therapeutic vaccine therapies, bispecific antibodies/fusion proteins and multitargeted kinase inhibitors, and antibody-drug conjugates (ADCs). Multiple concurrent investigations of novel therapeutics for patients with R/M HNSCC beyond anti-PD(L)1 inhibition are currently underway with some promising early results. Beyond immune checkpoint inhibition, novel immunotherapeutic strategies including therapeutic vaccines ranging from targeting human papillomavirus-specific epitopes to personalized neoantigen vaccines are ongoing with some early efficacy signals and large, randomized trials. Other novel weapons including bispecific antibodies, fusion proteins, and multitargeted kinase inhibitors leverage multiple concurrent targets and modulation of the tumor microenvironment to harness antitumor immunity and inhibition of protumorigenic signaling pathways with emerging promising results. Finally, as with other solid tumors, ADCs remain a promising therapeutic intervention either alone or in combination with immunotherapy for patients with R/M HNSCC. With early enthusiasm across novel therapies in R/M HNSCC, results of larger randomized trials in R/M HNSCC are eagerly awaited.

PD-1/CD80+ small extracellular vesicles from immunocytes induce cold tumours featured with enhanced adaptive immunosuppression.

Only a minority of cancer patients benefit from immune checkpoint blockade therapy. Sophisticated cross-talk among different immune checkpoint pathways as well as interaction pattern of immune checkpoint molecules carried on circulating small extracellular vesicles (sEV) might contribute to the low response rate. Here we demonstrate that PD-1 and CD80 carried on immunocyte-derived sEVs (I-sEV) induce an adaptive redistribution of PD-L1 in tumour cells. The resulting decreased cell membrane PD-L1 expression and increased sEV PD-L1 secretion into the circulation contribute to systemic immunosuppression. PD-1/CD80+ I-sEVs also induce downregulation of adhesion- and antigen presentation-related molecules on tumour cells and impaired immune cell infiltration, thereby converting tumours to an immunologically cold phenotype. Moreover, synchronous analysis of multiple checkpoint molecules, including PD-1, CD80 and PD-L1, on circulating sEVs distinguishes clinical responders from those patients who poorly respond to anti-PD-1 treatment. Altogether, our study shows that sEVs carry multiple inhibitory immune checkpoints proteins, which form a potentially targetable adaptive loop to suppress antitumour immunity.

Targeting PD-L1 in solid cancer with myeloid cells expressing a CAR-like immune receptor.

Introduction: Solid cancers Myeloid cells are prevalent in solid cancers, but they frequently exhibit an anti-inflammatory pro-tumor phenotype that contribute to the immunosuppressive tumor microenvironment (TME), which hinders the effectiveness of cancer immunotherapies. Myeloid cells' natural ability of tumor trafficking makes engineered myeloid cell therapy an intriguing approach to tackle the challenges posed by solid cancers, including tumor infiltration, tumor cell heterogenicity and the immunosuppressive TME. One such engineering approach is to target the checkpoint molecule PD-L1, which is often upregulated by solid cancers to evade immune responses. Method: Here we devised an adoptive cell therapy strategy based on myeloid cells expressing a Chimeric Antigen Receptor (CAR)-like immune receptor (CARIR). The extracellular domain of CARIR is derived from the natural inhibitory receptor PD-1, while the intracellular domain(s) are derived from CD40 and/or CD3ζ. To assess the efficacy of CARIR-engineered myeloid cells, we conducted proof-of-principle experiments using co-culture and flow cytometry-based phagocytosis assays in vitro. Additionally, we employed a fully immune-competent syngeneic tumor mouse model to evaluate the strategy's effectiveness in vivo. Result: Co-culturing CARIR-expressing human monocytic THP-1 cells with PD-L1 expressing target cells lead to upregulation of the costimulatory molecule CD86 along with expression of proinflammatory cytokines TNF-1α and IL-1ß. Moreover, CARIR expression significantly enhanced phagocytosis of multiple PD-L1 expressing cancer cell lines in vitro. Similar outcomes were observed with CARIR-expressing human primary macrophages. In experiments conducted in syngeneic BALB/c mice bearing 4T1 mammary tumors, infusing murine myeloid cells that express a murine version of CARIR significantly slowed tumor growth and prolonged survival. Conclusion: Taken together, these results demonstrate that adoptive transfer of PD-1 CARIR-engineered myeloid cells represents a promising strategy for treating PD-L1 positive solid cancers.

Prostate cancer therapy using immune checkpoint molecules to target recombinant dendritic cells.

PURPOSE: We developed immune checkpoint molecules to target recombinant dendritic cells (DCs) and verified their anti-tumor efficacy and immune response against prostate cancer. MATERIALS AND METHODS: DCs were generated from mononuclear cells in the tibia and femur bone marrow of mice. We knocked down the programmed death ligand 1 (PD-L1) on monocyte-derived DCs through siRNA PD-L1. Cell surface antigens were immune fluorescently stained through flow cytometry to analyze cultured cell phenotypes. Furthermore, we evaluated the efficacy of monocyte-derived DCs and recombinant DCs in a prostate cancer mouse model with subcutaneous TRAMP-C1 cells. Lastly, DC-induced mixed lymphocyte and lymphocyte-only proliferations were compared to determine cultured DCs' function. RESULTS: Compared to the control group, siRNA PD-L1 therapeutic DC-treated mice exhibited significantly inhibited tumor volume and increased tumor cell apoptosis. Remarkably, this treatment substantially augmented interferon-gamma and interleukin-2 production by stimulating T-cells in an allogeneic mixed lymphocyte reaction. Moreover, we demonstrated that PD-L1 gene silencing improved cell proliferation and cytokine production. CONCLUSIONS: We developed monocyte-derived DCs transfected with PD-L1 siRNA from mouse bone marrow. Our study highlights that PD-L1 inhibition in DCs increases antigen-specific immune responses, corroborating previous immunotherapy methodology findings regarding castration-resistant prostate cancer.

Immune checkpoint inhibitor (ICI)-based treatment beyond progression with prior immunotherapy in patients with driver-gene negative advanced non-small cell lung cancer.

BACKGROUND: No definite conclusion has yet to be reached for immunotherapy beyond progression(IBP) of first-line immunotherapy as the second-line treatment for advanced NSCLC patients with negative driver genes. Therefore a retrospective study was conducted to evaluate the efficacy of IBP in this population and investigated whether the cycles best response and progressive mode of first-line immunotherapy could affect the results. PATIENTS AND METHODS: The clinical data of patients with advanced NSCLC whose response was evaluated as progressive disease (PD) after receiving a PD-1/PD-L1 inhibitors as first-line therapy were retrospectively collected and the patients were assigned to the IBP and non-IBP groups. The overall survival (OS), progression-free survival (PFS) were evaluated between the two groups. The survival effects of cycles best response and progressive mode of first-line immunotherapy were also evaluated. RESULTS: Between January 2019 and January 2022, a total of 121 patients was evaluated as PD after first-line immunotherapy in our institution; 53 (43.8%) patients were included in the IBP group and 68 (56.2%) patients were included in the non-IBP group. The OS and PFS were no significantly different between the two groups in whole population. Further analysis revealed the OS was prolonged with the prolongation of first-line medication cycle. The median OS was 15.4m (15.4 vs 10.8 p=0.047) 16.1m (16.1 vs 10.8 p=0.039), 16.3m (16.3 vs 10.9 p=0.029) for patients with ≥4, ≥6, ≥8 cycles in first-line immunotherapy, respectively. The advantages of OS and PFS were also seen in the subgroup of PR (best response) and oligo progression of first-line immunotherapy. CONCLUSIONS: The clinical outcomes of IBP were similar to those of non-IBP in patients with PD after first-line immnuotherapy in advanced NSCLC. But more cycles, PR as best response and oligo progression in first-line was benefit.

Neurons upregulate PD-L1 via IFN/STAT1/IRF1 to alleviate damage by CD8+ T cells in cerebral malaria.

BACKGROUND: Cerebral malaria (CM) is the most lethal complication of malaria, and survivors usually endure neurological sequelae. Notably, the cytotoxic effect of infiltrating Plasmodium-activated CD8+ T cells on cerebral microvasculature endothelial cells is a prominent feature of the experimental CM (ECM) model with blood-brain barrier disruption. However, the damage effect of CD8+ T cells infiltrating the brain parenchyma on neurons remains unclear. Based on the immunosuppressive effect of the PD-1/PD-L1 pathway on T cells, our previous study demonstrated that the systemic upregulation of PD-L1 to inhibit CD8+ T cell function could effectively alleviate the symptoms of ECM mice. However, it has not been reported whether neurons can suppress the pathogenic effect of CD8+ T cells through the PD-1/PD-L1 negative immunomodulatory pathway. As the important inflammatory factor of CM, interferons can induce the expression of PD-L1 via different molecular mechanisms according to the neuro-immune microenvironment. Therefore, this study aimed to investigate the direct interaction between CD8+ T cells and neurons, as well as the mechanism of neurons to alleviate the pathogenic effect of CD8+ T cells through up-regulating PD-L1 induced by IFNs. METHODS: Using the ECM model of C57BL/6J mice infected with Plasmodium berghei ANKA (PbA), morphological observations were conducted in vivo by electron microscope and IF staining. The interaction between the ECM CD8+ T cells (immune magnetic bead sorting from spleen of ECM mice) and primary cultured cortical neurons in vitro was observed by IF staining and time-lapse photography. RNA-seq was performed to analyze the signaling pathway of PD-L1 upregulation in neurons induced by IFNß or IFNγ, and verified through q-PCR, WB, IF staining, and flow cytometry both in vitro and in vivo using IFNAR or IFNGR gene knockout mice. The protective effect of adenovirus-mediated PD-L1 IgGFc fusion protein expression was verified in ECM mice with brain stereotaxic injection in vivo and in primary cultured neurons via viral infection in vitro. RESULTS: In vivo, ECM mice showed infiltration of activated CD8+ T cells and neuronal injury in the brain parenchyma. In vitro, ECM CD8+ T cells were in direct contact with neurons and induced axonal damage, as an active behavior. The PD-L1 protein level was elevated in neurons of ECM mice and in primary cultured neurons induced by IFNß, IFNγ, or ECM CD8+ T cells in vitro. Furthermore, the IFNß or IFNγ induced neuronal expression of PD-L1 was mediated by increasing STAT1/IRF1 pathway via IFN receptors. The increase of PD-L1 expression in neurons during PbA infection was weakened after deleting the IFNAR or IFNGR. Increased PD-L1 expression by adenovirus partially protected neurons from CD8+ T cell-mediated damage both in vitro and in vivo. CONCLUSION: Our study demonstrates that both type I and type II IFNs can induce neurons to upregulate PD-L1 via the STAT1/IRF1 pathway mediated by IFN receptors to protect against activated CD8+ T cell-mediated damage, providing a targeted pathway to alleviate neuroinflammation during ECM.

Nivolumab plus chemotherapy or ipilimumab versus chemotherapy in patients with advanced esophageal squamous cell carcinoma (CheckMate 648): 29-month follow-up from a randomized, open-label, phase III trial.

BACKGROUND: First-line nivolumab plus chemotherapy and nivolumab plus ipilimumab both demonstrated significant overall survival (OS) benefit versus chemotherapy in previously untreated patients with advanced esophageal squamous cell carcinoma (ESCC) in the CheckMate 648 trial, leading to approvals of both nivolumab-containing regimens in many countries. We report longer-term follow-up data. METHODS: This open-label, phase III trial (NCT03143153) enrolled adults with previously untreated, unresectable, advanced, recurrent, or metastatic ESCC. Patients were randomized 1:1:1 to nivolumab plus chemotherapy, nivolumab plus ipilimumab, or chemotherapy. Primary endpoints were OS and progression-free survival (PFS) by blinded independent central review. Hierarchical testing was performed first in patients with tumor cell programmed death ligand 1 (PD-L1) expression of ≥1% and then in the overall population. RESULTS: A total of 970 patients were randomly assigned. After 29 months of minimum follow-up, nivolumab plus chemotherapy continued to demonstrate improvement in OS versus chemotherapy (hazard ratio [HR] = 0.59 [95% CI: 0.46-0.76]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.78 [95% CI: 0.65-0.93]) and with nivolumab plus ipilimumab versus chemotherapy (HR = 0.62 [95% CI: 0.48-0.80]) in patients with tumor cell PD-L1 expression of ≥1% and in the overall population (HR = 0.77 [95% CI: 0.65-0.92]). In patients with tumor cell PD-L1 expression of ≥1%, nivolumab plus chemotherapy demonstrated PFS benefit versus chemotherapy (HR = 0.67 [95% CI: 0.51-0.89]); PFS benefit was not observed with nivolumab plus ipilimumab versus chemotherapy (HR = 1.04 [95% CI: 0.79-1.36]). Among all treated patients (n = 936), Grade 3-4 treatment-related adverse events were reported in 151 (49%, nivolumab plus chemotherapy), 105 (32%, nivolumab plus ipilimumab), and 110 (36%, chemotherapy) patients. CONCLUSIONS: Nivolumab plus chemotherapy and nivolumab plus ipilimumab continued to demonstrate clinically meaningful OS benefit versus chemotherapy with no new safety signals identified with longer follow-up, further supporting use as first-line standard treatment options for patients with advanced ESCC.

Efficacy and safety of PD-1/PD-L1 inhibitors in elderly patients with advanced non-small cell lung cancer.

OBJECTIVE: This study aimed to investigate the efficacy and safety of PD-1/PD-L1 inhibitors in treatment of elderly patients with advanced non-small cell lung cancer (NSCLC). METHODS: Patients with advanced NSCLC ≥70 years old who received PD-1/PD-L1 inhibitors in our hospital were retrospectively analyzed. According to age, the patient were stratified as follows: 70-75 years old, 76-80 years old, and >80 years old. Kaplan-Meier method was used for survival analysis, and univariate and multivariate Cox proportional hazards regression models were used to analyze the correlation between different clinical characteristics and survival. RESULTS: A total of 58 elderly patients with advanced non-small cell cancer were enrolled in this study. Patients aged 70-75, 76-80, and >80 years old were 32, 19, and 7, respectively. For the all, median OS was 17.0 months, and PFS was 7.0 months. PFS and OS did not differ according to age (P = 0.396, 0.054, respectively). Univariate analysis showed that PS of 0-1, stage III, first-line therapy and irAEs were associated with longer PFS, and PS of 0-1, stage III, and first-line therapy were associated with longer OS. Multivariate analysis showed that patients with stage III had longer PFS. PFS and OS of patients with PS ≥ 2 were significantly shorter than those of patients with PS of 0-1. CONCLUSIONS: In the present real-world retrospective cohort, PD-1/PD-L1 inhibitors are effective and well tolerated in elderly patients with advanced NSCLC. Immunotherapy should be actively used as early as possible in older patients advanced NSCLC.

[Progress in PD-1/PD-L1, PD-L2 signaling pathway and its role in host anti-tuberculosis immunity].

Programmed cell death 1 (PD-1) and its ligands, PD-L1 and PD-L2, expressed on a variety of immune cells, play multiple regulatory roles in the host immune response to Mycobacterium tuberculosis infection. In this study, we reviewed that the regulatory roles of PD-1/PD-L1, PD-L2 signaling in the host adaptive immune response, such as the innate response of macrophages, and the interaction between T cells and macrophages in response to MTB. In addition, during MTB infection, PD-1/PD-L1, PD-L2 signaling is also involved in the host inflammatory response, as well as the potential roles of PD-1/PD-L1, PD-L2 in the diagnosis and treatment of tuberculosis.

Protein kinase CK2α is overexpressed in classical hodgkin lymphoma, regulates key signaling pathways, PD-L1 and may represent a new target for therapy.

Introduction: In classical Hodgkin lymphoma (cHL), the survival of neoplastic cells is mediated by the activation of NF-κB, JAK/STAT and PI3K/Akt signaling pathways. CK2 is a highly conserved serine/threonine kinase, consisting of two catalytic (α) and two regulatory (ß) subunits, which is involved in several cellular processes and both subunits were found overexpressed in solid tumors and hematologic malignancies. Methods and results: Biochemical analyses and in vitro assays showed an impaired expression of CK2 subunits in cHL, with CK2α being overexpressed and a decreased expression of CK2ß compared to normal B lymphocytes. Mechanistically, CK2ß was found to be ubiquitinated in all HL cell lines and consequently degraded by the proteasome pathway. Furthermore, at basal condition STAT3, NF-kB and AKT are phosphorylated in CK2-related targets, resulting in constitutive pathways activation. The inhibition of CK2 with CX-4945/silmitasertib triggered the de-phosphorylation of NF-κB-S529, STAT3-S727, AKT-S129 and -S473, leading to cHL cell lines apoptosis. Moreover, CX-4945/silmitasertib was able to decrease the expression of the immuno-checkpoint CD274/PD-L1 but not of CD30, and to synergize with monomethyl auristatin E (MMAE), the microtubule inhibitor of brentuximab vedotin. Conclusions: Our data point out a pivotal role of CK2 in the survival and the activation of key signaling pathways in cHL. The skewed expression between CK2α and CK2ß has never been reported in other lymphomas and might be specific for cHL. The effects of CK2 inhibition on PD-L1 expression and the synergistic combination of CX-4945/silmitasertib with MMAE pinpoints CK2 as a high-impact target for the development of new therapies for cHL.

A study on expression of programmed death ligand-1 in small cell lung carcinoma and correlation with clinicopathological parameters.

Small cell lung carcinoma (SCLC) is characterized by rapid growth and an aggressive clinical course. Standard therapy regimes have limited effects on disease course; therefore the prognosis of SCLC is poor. In the current study, the frequency of programmed death ligand 1 (PD-L1) expression in SCLC and its correlation with clinico-pathological features were evaluated. The study included 100 cases of SCLC wherein testing for PD-L1 was done with the SP263 clone on the Ventana benchmark XT system. Cases with > 1% PD-L1 expression in tumour cells or immune cells were categorized as positive. PD-L1 expression was identified in 14% of cases using the cut-off of ≥ 1%. The tumour proportion score was 10% and the immune proportion score was 9.78% using a cut-off of ≥ 1%. PD-L1 positive expression was more frequent in the male population with age > 40 years. All the patients with positive PD-L1 expression were smokers. In the PD-L1 positive group, presence of necrosis was identified in 71.4% of cases and when compared with the PD-L1 negative subgroup this finding was statistically significant (p = 0.010). Personalized targeted therapy for cases of SCLC is still under evaluation. The use of immunotherapeutic targets, such as PD-L1, may help to define a new treatment strategy for SCLC. Development of new treatment strategies may improve prognosis and survival.

PD-1/PD-L1 inhibitors for early and middle stage microsatellite high-instability and stable colorectal cancer: a review.

BACKGROUND: Programmed cell death receptor 1 (PD-1) and programmed cell death ligand 1 (PD-L1) are important immune checkpoint molecules that contribute to tumor immune evasion. However, the main treatment modalities for patients with early and intermediate stage colorectal cancer (CRC) are surgery, and the role of PD-1/PD-L1 inhibitors in these patients is not yet clear. Therefore, this study aims to review the treatment progress of PD-1/PD-L1 inhibitors for early- and intermediate-stage microsatellite high-instability (MSI-H) and stable (MSS) colorectal cancer, in order to provide more options for patients with early- and intermediate-stage colorectal cancer. MATERIALS AND METHODS: A scoping review of clinical trial registries ( Clinicaltrials.gov and EU clinical trial registers) and PubMed/Medline database of trials on PD-1/PD-L1 Inhibitors for early and middle-stage MSI-H and MSS CRC was done up to March 2024. RESULTS: A total of 19 trials related to early to mid-stage MSH-I or MSS CRC were included. Among them, 6 trials are in recruiting status, 3 trials are in active, not recruiting status, 3 trials are completed, 1 trial is terminated, and 1 trial is unknown. Of these, 9 trials involve MSI-H type CRC, and 10 trials involve MSS type CRC. Preclinical phase I/II trials are predominant, with only 3 clinical phase III trials. In trials related to MSI-H type CRC, 4 studies involve PD-1/PD-L1 inhibitors combined with neoadjuvant therapy, and 5 studies involve combination therapy. In trials related to MSS type CRC, 3 studies involve PD-1/PD-L1 inhibitors combined with targeted therapy, 2 studies involve PD-1/PD-L1 inhibitors combined with chemotherapy, 1 study involves PD-1/PD-L1 inhibitor combined immunotherapy, 1 study involves PD-1/PD-L1 inhibitors combined with bacterial therapy, and 3 studies involve PD-1/PD-L1 inhibitors combined with comprehensive therapy. As for primary outcome measures, 4 trials select pathological complete response rates, 3 trials select progression-free survival rate, 3 trials select objective response rate, 3 trials select overall survival rate, 4 trials select disease-free survival rate, 1 trial selects clinical complete response rate, and 1 trial selects percentage of participants with a dose-limiting toxicity. CONCLUSION: For early- and middle-stage MSI-H and MSS CRC, PD-1/PD-L1 inhibitors have shown some therapeutic efficacy, as evidenced by phase I/II studies. However, contemporary trial designs exhibit heterogeneity, with relatively few inclusion criteria, the use of various drug combinations and regimens, and significant variations in reported endpoints. Nevertheless, more double-arm, multicenter, randomized controlled trials are still needed to confirm the efficacy of immunotherapy.

Comparative characterization of two monoclonal antibodies targeting canine PD-1.

Monoclonal antibodies targeting immune checkpoints have revolutionized oncology. Yet, the effectiveness of these treatments varies significantly among patients, and they are associated with unexpected adverse events, including hyperprogression. The murine research model used in drug development fails to recapitulate both the functional human immune system and the population heterogeneity. Hence, a novel model is urgently needed to study the consequences of immune checkpoint blockade. Dogs appear to be uniquely suited for this role. Approximately 1 in 4 companion dogs dies from cancer, yet no antibodies are commercially available for use in veterinary oncology. Here we characterize two novel antibodies that bind canine PD-1 with sub-nanomolar affinity as measured by SPR. Both antibodies block the clinically crucial PD-1/PD-L1 interaction in a competitive ELISA assay. Additionally, the antibodies were tested with a broad range of assays including Western Blot, ELISA, flow cytometry, immunofluorescence and immunohistochemistry. The antibodies appear to bind two distinct epitopes as predicted by molecular modeling and peptide phage display. Our study provides new tools for canine oncology research and a potential veterinary therapeutic.

Plasminogen activator inhibitor-1 promotes immune evasion in tumors by facilitating the expression of programmed cell death-ligand 1.

Background: Increased levels of plasminogen activator inhibitor-1 (PAI-1) in tumors have been found to correlate with poor clinical outcomes in patients with cancer. Although abundant data support the involvement of PAI-1 in cancer progression, whether PAI-1 contributes to tumor immune surveillance remains unclear. The purposes of this study are to determine whether PAI-1 regulates the expression of immune checkpoint molecules to suppresses the immune response to cancer and demonstrate the potential of PAI-1 inhibition for cancer therapy. Methods: The effects of PAI-1 on the expression of the immune checkpoint molecule programmed cell death ligand 1 (PD-L1) were investigated in several human and murine tumor cell lines. In addition, we generated tumor-bearing mice and evaluated the effects of a PAI-1 inhibitor on tumor progression or on the tumor infiltration of cells involved in tumor immunity either alone or in combination with immune checkpoint inhibitors. Results: PAI-1 induces PD-L1 expression through the JAK/STAT signaling pathway in several types of tumor cells and surrounding cells. Blockade of PAI-1 impedes PD-L1 induction in tumor cells, significantly reducing the abundance of immunosuppressive cells at the tumor site and increasing cytotoxic T-cell infiltration, ultimately leading to tumor regression. The anti-tumor effect elicited by the PAI-1 inhibitor is abolished in immunodeficient mice, suggesting that PAI-1 blockade induces tumor regression by stimulating the immune system. Moreover, combining a PAI-1 inhibitor with an immune checkpoint inhibitor significantly increases tumor regression. Conclusions: PAI-1 protects tumors from immune surveillance by increasing PD-L1 expression; hence, therapeutic PAI-1 blockade may prove valuable in treating malignant tumors.

In Search of Better Peptide-(Derived from PD-L2)-Based Immune Checkpoint Inhibitors.

Current anti-cancer immune checkpoint therapy relies on antibodies that primarily target the PD-1/PD-L1(-L2) negative regulatory pathway. Although very successful in some cases for certain cancers, these antibodies do not help most patients who, presumably, should benefit from this type of therapy. Therefore, an unmet clinical need for novel, more effective drugs targeting immune checkpoints remains. We have developed a series of high-potency peptide inhibitors interfering with PD-1/PD-L1(-L2) protein-protein interaction. Our best peptide inhibitors are 12 and 14 amino acids long and show sub-micromolar IC50 inhibitory activity in the in vitro assay. The positioning of the peptides within the PD-1 binding site is explored by extensive modeling. It is further supported by 2D NMR studies of PD-1/peptide complexes. These results reflect substantial progress in the development of immune checkpoint inhibitors using peptidomimetics.

Radiotherapy and immunology.

The majority of cancer patients receive radiotherapy during the course of treatment, delivered with curative intent for local tumor control or as part of a multimodality regimen aimed at eliminating distant metastasis. A major focus of research has been DNA damage; however, in the past two decades, emphasis has shifted to the important role the immune system plays in radiotherapy-induced anti-tumor effects. Radiotherapy reprograms the tumor microenvironment, triggering DNA and RNA sensing cascades that activate innate immunity and ultimately enhance adaptive immunity. In opposition, radiotherapy also induces suppression of anti-tumor immunity, including recruitment of regulatory T cells, myeloid-derived suppressor cells, and suppressive macrophages. The balance of pro- and anti-tumor immunity is regulated in part by radiotherapy-induced chemokines and cytokines. Microbiota can also influence radiotherapy outcomes and is under clinical investigation. Blockade of the PD-1/PD-L1 axis and CTLA-4 has been extensively investigated in combination with radiotherapy; we include a review of clinical trials involving inhibition of these immune checkpoints and radiotherapy.

Determinants of gastric cancer immune escape identified from non-coding immune-landscape quantitative trait loci.

The landscape of non-coding mutations in cancer progression and immune evasion is largely unexplored. Here, we identify transcrptome-wide somatic and germline 3' untranslated region (3'-UTR) variants from 375 gastric cancer patients from The Cancer Genome Atlas. By performing gene expression quantitative trait loci (eQTL) and immune landscape QTL (ilQTL) analysis, we discover 3'-UTR variants with cis effects on expression and immune landscape phenotypes, such as immune cell infiltration and T cell receptor diversity. Using a massively parallel reporter assay, we distinguish between causal and correlative effects of 3'-UTR eQTLs in immune-related genes. Our approach identifies numerous 3'-UTR eQTLs and ilQTLs, providing a unique resource for the identification of immunotherapeutic targets and biomarkers. A prioritized ilQTL variant signature predicts response to immunotherapy better than standard-of-care PD-L1 expression in independent patient cohorts, showcasing the untapped potential of non-coding mutations in cancer.