Higher serum sPD-L1 levels after radiotherapy indicate poor outcome in hepatocellular carcinoma patients

BackgroundOur preclinical research reveals that radiotherapy (RT) promoted PD-L1 upregulation in tumor tissues and that higher PD-L1 after RT worsened the prognosis through immunosuppression. We sought to validate our experimental results in clinical cohorts and promote clinical application.Patients and methodsIn cohort 1, formalin-fixed paraffin-embedded samples were obtained from 46 HCC patients, 23 of whom received preoperative RT and the other 23 received direct surgery. A prospectively collected database contained 122 HCC patients treated with liver RT were enrolled in cohort 2. Blood samples were taken a day before and two weeks after RT. Patients in cohort 2 were further divided into two groups, exploration (73 patients) and validation (49 patients) groups.ResultsIn cohort 1, RT increased the expression of PD-L1 in tumor tissues (p = 0.001), and PD-L1 levels were associated with decreased cytotoxic T-cell infiltration and a trend toward poor prognosis (p = 0.14). Moreover, PD-L1 expression in tumor tissue positively correlated with soluble (s) PD-L1 in serum (R = 0.421, p = 0.046). Then, in cohort 2, we revealed RT increased sPD-L1 in serum (p < 0.001), which was associated with the number of circulating CD8+ T cells (R = -0.24, p = 0.036), indicating poor survival. Furthermore, patients with higher rate of sPD-L1 increase after RT have better treatment response (p < 0.001), PFS (p = 0.032) and OS (p = 0.045).ConclusionHigher post-RT serum sPD-L1, which may potentiate immune suppression effects, indicates a poor prognosis for HCC patients treated with RT.     

Knockdown of CDK5 down-regulates PD-L1 via the ubiquitination-proteasome pathway and improves antitumor immunity in lung adenocarcinoma

Although immunotherapy (anti-PD-1/PD-L1 antibodies) has been approved for clinical treatment of lung cancer, only a small proportion of patients respond to monotherapy. Hence, understanding the regulatory mechanism of PD-L1 is particularly important to identify optimal combinations. In this study, we found that inhibition of CDK5 induced by shRNA or CDK5 inhibitor leads to reduced expression of PD-L1 protein in human lung adenocarcinoma cells, while the mRNA level is not substantially altered. The PD-L1 protein degradation is mediated by E3 ligase TRIM21 via ubiquitination-proteasome pathway. Subsequently, we studied the function of CDK5/PD-L1 axis in LUAD. In vitro, the absence of CDK5 in mouse Lewis lung cancer cell (LLC) has no effect on cell proliferation. However, the attenuation of CDK5 or combined with anti-PD-L1 greatly suppresses tumor growth in LLC implanted mouse models in vivo. Disruption of CDK5 elicits a higher level of CD3⁺, CD4⁺ and CD8⁺ T cells in spleens and lower PD-1 expression in CD4⁺ and CD8⁺ T cells. Our findings highlight a role for CDK5 in promoting antitumor immunity, which provide a potential therapeutic target for combined immunotherapy in LUAD.     

PVR/TIGIT and PD-L1/PD-1 expression predicts survival and enlightens combined immunotherapy in lung squamous cell carcinoma

PVR/TIGIT and PD-L1/PD-1 axes play essential roles in tumor immune evasion and could be potential targets for combined immunotherapy. We aimed to evaluate the expression status of the above-mentioned immune markers in lung squamous cell carcinoma (LUSC), and investigate their survival impact and relevance with the immune microenvironment and clinicopathological features. We retrospectively collected specimens from 190 LUSC patients, who underwent pulmonary surgeries, and we performed immunohistochemistry assays of PVR, TIGIT, PD-L1, PD-1 and CD8. In our cohort, the positive rate of PVR was 85.8%, which was much higher than the positive rate of PD-L1 at 26.8%. A total of 32 (16.8%) patients demonstrated co-expression of PVR/PD-L1. High TIGIT density was correlated with positive PD-L1 expression, high PD-1 density, and high CD8 density (PD-L1, P=0.033; PD-1, P<0.001; CD8, P<0.001), and positive PVR expression was correlated with positive PD-L1 expression (P=0.046). High TIGIT density and high PVR/TIGIT expression were correlated with advanced TNM stage (TIGIT density, P=0.020; PVR/TIGIT expression, P=0.041). Patients with positive PVR expression, high TIGIT density, high PVR/TIGIT expression and PVR/PD-L1 co-expression exhibited a significantly worse prognosis (PVR, P=0.038; TIGIT, P=0.027; PVR/TIGIT, P=0.014; PVR/PD-L1, P=0.018). Multivariate analysis demonstrated that PVR/PD-L1 co-expression (Hazard ratio [HR], 1.756, 95% CI, 1.152-2.676, P=0.009) was an independent prognostic factor in LUSC patients. In conclusion, we demonstrated the expression status of PVR/TIGIT and PD-L1/PD-1 in LUSC. PVR/PD-L1 co-expression was an independent prognostic factor in LUSC patients and may serve as a potential predictive biomarker for dual-targeting immunotherapy.     

RNA interference targeting programmed death receptor-1 improves immune functions of tumor-specific T cells

Adoptive cell transfer (ACT), either using rapidly expanded tumor infiltrating lymphocytes or T-cell receptor transduced peripheral blood lymphocytes, can be considered one of the most promising approaches in cancer immunotherapy. ACT results in the repopulation of the host with high frequencies of tumor-specific T cells; however, optimal function of these cells within the tumor micro-environment is required to reach long-term tumor clearance. We and others have shown that ongoing anti-tumor immune responses can be impaired by the expression of ligands, such as PD-L1 (B7-H1) on tumor cells. Such inhibitory molecules can affect T cells at the effector phase via their receptor PD-1. PD-L1/PD-1 interaction has indeed been shown crucial in inducing T-cell anergy and maintaining peripheral tolerance. In order to maximize anti-tumor responses, antibodies that target the PD-1/PD-L1 axis are currently in phase I/II trials. Alternatively, a more refined approach could be the selective targeting of PD-1 in tumor-specific T cells to obtain long-term resistance against PD-1-mediated inhibition. We addressed whether this goal could be achieved by means of retroviral siRNA delivery. Effective siRNA sequences resulting in the reduction of surface PD-1 expression led to improved murine as well as human T-cell immune functions in response to PD-L1 expressing melanoma cells. These data suggest that blockade of PD-1-mediated T-cell inhibition through siRNA forms a promising approach to achieve long-lasting enhancement of tumor-specific T-cell function in adoptive T-cell therapy protocols.     

N6-methyladenosine RNA modification in PD-1/PD-L1: Novel implications for immunotherapy

Cancer immunotherapy has been shown to achieve significant antitumor effects in a variety of malignancies. Out of all the immune checkpoint molecules, PD-1/PD-L1 inhibitor therapy has achieved great success. However, only some cancer patients benefit from this treatment strategy owing to drug resistance. Therefore, identifying the underlying modulators of the PD-1/PD-L1 pathway to completely comprehend the mechanisms of anti-PD-1/PD-L1 treatment is crucially important. Recent research has validated that m6A modification plays a critical role in the PD-1/PD-L1 axis, thus regulating the immune response and immunotherapy strategies. In this review, we summarized the latest research on the regulation of m6A modification in PD-1/PD-L1 pathways in cancer proliferation, invasion, and prognosis based on different kinds of cancers and discussed the possible mechanisms. We also reviewed m6A-associated lncRNAs in the regulation of the PD-1/PD-L1 pathway. More importantly, we outlined the influence of m6A modulation on anti-PD-1 therapy and m6A-related molecules that could predict the curative effect of anti-PD-1/PD-L1 therapy. Further studies exploring the definitive regulation of m6A on the PD1/PD-1 pathway and immunotherapy are needed, which may address some of the current limitations in immunotherapy.     

不同检测策略在预测非小细胞肺癌的PD1/PD-L1抑制剂临床疗效中的应用

近10年来,程序性死亡因子1(programmed death-1,PD-1)及其配体(programmed death ligand-1,PD-L1)的抑制剂在非小细胞肺癌(non-small cell lung cancer,NSCLC)的临床治疗中取得了重大突破,有望改变晚期NSCLC的治疗方式。然而,PD-1/PD-L1抑制剂在对NSCLC的治疗中需要借助有效的生物标志物以寻找受益人群(约20%～40%)。目前,临床上主要的判断标准是PD-L1的表达水平。本文综述了近年来在NSCLC中,与预测PD-1/PD-L1抑制剂疗效的PD-L1表达相关的检测方法,包括免疫组化、基于DNA/RNA水平检测、可溶性PD-L1的检测、正电子发射断层显像(positron emission tomography,PET)技术、多重免疫组化技术、流式细胞术和液体活检技术等,着重探讨了不同检测策略在评价PD-L1表达上的最新进展及应用前景,从而推动其在NSCLC免疫治疗中的临床应用。     

Correlation between PD-1/PD-L1 expression and polarization in tumor-associated macrophages: A key player in tumor immunotherapy

Tumor immunotherapy, such as PD-1/PD-L1 blockade, has shown promising clinical efficacy in patients with various types of tumors. However, the response to PD-1/PD-L1 blockade in a majority of malignancies is limited, indicating an urgent need for a deeper understanding of the mechanisms of PD-1/PD-L1 axis-mediated tumor tolerance. As the most abundant immune cells in the tumor stroma, macrophages display multiple phenotypes and functions in response to the stimuli of the tumor microenvironment. PD-1/PD-L1 has been demonstrated to be highly expressed in tumor-associated macrophages (TAMs), and TAM polarization has been shown to be important during tumor progression. In this review, we outline the relationship between TAM PD-1/PD-L1 expression and polarizations, summarize the involvement of M2 TAMs in PD-1/PD-L1-mediated T-cell exhaustion, and discuss improved approaches for overcoming PD-1/PD-L1 blockade resistance by inducing M2/M1 switching of TAMs.     

High PD-L1 Expression Correlates with Metastasis and Poor Prognosis in Oral Squamous Cell Carcinoma

PD-L1 has been widely demonstrated to contribute to failed antitumor immunity. Blockade of PD-L1 with monoclonal antibody could modulate the tumor immune environment to augment immunotherapy. PD-L1 expression is also detected in several types of cancer and is associated with poor prognosis. However, the prognostic role of PD-L1 in oral squamous cell carcinoma (OSCC) is still controversial. Our aim was to determine the role of PD-L1 in the prognosis of OSCC patients to identify its potential therapeutic relevance. PD-L1 immunoreactivity was analyzed by immunohistochemistry in 305 cancer specimens from primary OSCC patients. The medium follow-up time after surgery was 3.8 years (range from 0.1 to 11.1 years). The prognostic value of PD-L1 on overall survival was determined by Kaplan-Meier analysis and Cox proportional hazard models. Higher PD-L1 expression is more likely in tumor tissues of female than male OSCC patients (P = 0.0062). Patients with distant metastasis also had high PD-L1 expression (P = 0.0103). Multivariate analysis identified high PD-L1 expression as an independent risk factor in males and smokers (males: hazard ratio = 1.556, P = 0.0077; smokers: hazard ratio = 2.058, P = 0.0004). We suggest that PD-L1 expression, determined by IHC staining, could be an independent prognostic marker for OSCC patients who are male or who have a smoking habit.     

Correlation between immunotherapy biomarker PD-L1 expression and genetic alteration in patients with non-small cell lung cancer

Programmed death-ligand 1 (PD-L1) has been widely used in immunotherapy evaluation of patients with non-small cell lung cancer (NSCLC). However, the effect is not particularly ideal, and the association between PD-L1 and genetic alterations requires more exploration. Here, we performed targeted next-generation sequencing and PD-L1 immunohistochemistry (IHC) testing for PD-L1 expression on both tumor cells (TCs) and tumor-infiltrating immune cells (ICs) in 1549 patients. Our studies showed that surgical method of resection was positively correlated with IC+, and a low tumor mutation burden (TMB) was negatively correlated with TC+. Furthermore, we found that EGFR was mutually exclusive with both ALK and STK11. In addition, the features between PD-L1 expression status and genomic alterations were characterized. These results suggest that clinical characteristics and molecular phenotypes are associated with PD-L1 expression signatures, which may provide novel insights for improving the efficiency of immune checkpoint inhibitors (ICIs) in immunotherapy.     

Poliovirus receptor (PVR) mediates carboplatin-induced PD-L1 expression in non-small-cell lung cancer cells

Programmed death-ligand-1 (PD-L1) is an immune suppressor that inhibits T cell based immunity. Anti-PD-L1/PD-1 immunotherapy benefits those patients receiving platinum-based combinational chemotherapy. However, the underlying mechanism is still largely unknown. In this study, we found that carboplatin could induce PD-L1 expression in NSCLC H292, A549 and H1299 cells in a dose-dependent manner. mRNA sequencing and the subsequent validation assays found that carboplatin significantly induced PVR expression, which is considered as an immuno-adhesion molecule. Mechanistically, PVR knockdown significantly abrogated carboplatin-induced PD-L1 expression. Functionally, knockdown of PVR significantly reversed the CD3⁺ T cells proliferation inhibition caused by carboplatin increased PD-L1. Moreover, the carboplatin-induced PVR and subsequent up-regulation of PD-L1 might be mediated via the EGFR, PI3K/AKT, and ERK signaling pathways. Immunohistochemical staining results showed that the PD-L1 expression was positively associated with PVR expression in clinical NSCLC samples. Our study reveals a novel regulatory mechanism of PD-L1 expression, provides evidence that carboplatin inhibits tumor immune response by up-regulating PD-L1 expression and explains the rationale for combining platinum-based chemotherapy with PD-L1/PD-1 inhibitors.     

LSD1 silencing contributes to enhanced efficacy of anti-CD47/PD-L1 immunotherapy in cervical cancer

Anti-CD47/PD-L1 immunotherapies aiming to enhance antitumor immunity are being intensively investigated and show promising results in cancer therapy; however, not all patients treated with these new drugs respond. Thus, developing new immunotherapy agents or combination treatments to enhance the efficacy of immunotherapy is an urgent challenge. Here, we found that LSD1 knockdown directly downregulated the expression of CD47 and PD-L1 through upregulating H3K4me2 levels in the CD47 and CD274 promoter regions. In addition, the LSD1/wild-type p53/miR-34a signaling axis was also involved in the regulation of CD47/PD-L1 expression by targeting the 3′ untranslated regions (3′UTRs) of CD47/PD-L1. Further, the results showed that an LSD1 inhibitor (ORY-1001) combined with anti-CD47/PD-L1 monoclonal antibodies inhibited tumor growth in an established subcutaneous xenograft model more effectively than a single blockade strategy. Collectively, these findings indicate that LSD1 inhibition enhances the therapeutic efficacy of PD-L1/CD47 blockade by reducing CD47 and PD-L1 expression in cervical cancer.Subject terms: Tumour immunology, Cell signalling     

CMTM6, the newly identified PD-L1 regulator,correlates with PD-L1 expression in lung cancers

Modulation of Immune check point regulators, especially the PD-1/PD-L1 axis, plays a critical role in successful management of a small proportion of lung cancer patients, but not so effective in the rest of lung cancer patients. A better understanding of immunotherapy non-responsive or resistant patients therefore warranted for future development of novel therapeutics. The newly identified regulator CMTM6 (CKLF-like MARVEL transmembrane domain containing 6) has been reported to serves as the stabilizer of PD-L1 and enhances the inhibitory effect of PD-L1 on immune system in both cell line and animal models, but its clinical relevance associated with PD-L1 is unknown and the current study is designed to address this question. The study using immunohistochemistry demonstrated that CMTM6 positivity from 15 out of 19 types of cancers with our in-house tissue microarray, and PD-L1 expression is always found only in CMTM6 positive cancers. CMTM6 and PD-L1 expression were analyzed in 81 lung cancer patient sample, and we observed that CMTM6 expression correlated with cancer histotypes and inversely correlated with cancer metastases, but not with patients’ age and gender. No PD-L1 expression was observed in negative CMTM6 samples. Higher expression PD-L1 is also associated with higher CMTM6 expression. In summary, CMTM6 expression is associated with PD-L1 expression, as well as lung cancer histotypes and metastasis. The results thus for the first time confirmed earlier reports on CMTM6/PD-L1 connection, from a clinical aspect of analysis.     

Licochalcone A inhibits interferon-gamma-induced programmed death-ligand 1 in lung cancer cells

BackgroundProgrammed death-ligand 1 (PD-L1), which can be induced by interferon-gamma (IFN-γ) in the tumor microenvironment, is a critical immune checkpoint in cancer immunotherapy. Natural products which reduce IFN-γ-induced PD-L1 might be exert immunotherapy effect. Licochalcone A (LCA), a natural compound derived from the root of Glycyrrhiza inflata Batalin. (Fabaceae), was found to interfere IFN-γ-induced PD-L1.PurposeThe aim of this study is to further clarify the effect and the mechanism of LCA on inhibiting IFN-γ-induced PD-L1 in lung cancer cells.MethodsThe expression levels of PD-L1 were evaluated by flow cytometry, western blot and qRT-PCR. Click-iT protein synthesis assay and luciferase assay were used to identify the effect of LCA on protein synthesis. Jurkat T cell proliferation and apoptosis in the co-culture system were detected by flow cytometry. Flow cytometry was also applied to evaluate reactive oxygen species (ROS) generation.ResultsLCA downregulated IFN-γ-induced PD-L1 protein expression and membrane localization in human lung cancer cells, regardless of inhibiting PD-L1 mRNA level or promoting its protein degradation. LCA decreased apoptosis and proliferative inhibition of Jurkat T cells caused by IFN-γ-induced PD-L1-expressing in A549 cells in the co-culture system. Strikingly, LCA was verified as a protein synthesis inhibitor, which reduced both cap-dependent and -independent translation. LCA inhibited PD-L1 translation, likely due to inhibition of 4EBP1 phosphorylation (Ser 65) and activation of PERK-eIF2α pathway. Furthermore, LCA induced ROS generation in a time-dependent manner in lung cancer cells. N-acetyl-L-cysteine (NAC) not only revered ROS generation triggered by LCA but also restored IFN-γ-induced expression of PD-L1. Both the inhibition of 4EBP1 phosphorylation (Ser 65) and activation of PERK-eIF2α axis triggered by LCA was restored by co-treatment with NAC.ConclusionLCA abrogated IFN-γ-induced PD-L1 expression via ROS generation to abolish the protein translation, indicating that LCA has the potential to be applied in cancer immunotherapy.     

Programmed death ligand-1 over-expression correlates with malignancy and contributes to immune regulation in ovarian cancer

The programmed death-1 (PD-1) pathway is important in the maintenance of peripheral tolerance and homeostasis through suppression of T cell receptor signaling. As such, it is employed by many tumors as a means of immune escape. We have investigated the role of this pathway in human ovarian cancer (OC) to assess its potential role as a diagnostic and/or prognostic marker and therapeutic target, following recent clinical trial success of antibody therapy directed at this pathway. We show programmed death ligand-1 (PD-L1) expression on monocytes in the ascites and blood of patients with malignant OC is strikingly higher than those with benign/borderline disease, with no overlap in the values between these groups. We characterize the regulation of this molecule and show a role of IL-10 present in ascitic fluid. Flow cytometric analysis of T cells present in the ascites and blood showed a correlation of PD-1 expression with malignant tumors versus benign/borderline, in a similar manner to PD-L1 expression on monocytes. Finally, we demonstrate functional links between PD-L1 expression on monocytes and OC tumor cells with suppression of T cell responses. Overall, we present data based on samples obtained from women with ovarian cancer, suggesting the PD-1 pathway may be used as a reliable diagnostic marker in OC, as well as a viable target for use with PD-1/PD-L1-directed antibody immunotherapy.     

Analysis of Expression of Programmed Cell Death 1 Ligand 1 (PD-L1) in Malignant Pleural Mesothelioma (MPM)

Background

The increasing incidence and poor outcome associated with MPM requires finding effective treatment for this disease. PD1/PD-L1 pathway plays a central role in tumor immune evasion and appears to be predictive and prognostic marker. PD-L1 is expressed in many different human cancers but its role in MPM has yet to be established. The aim of this study is to evaluate the expression of PD-L1 in MPM.

Methods

119 MPM patients (p) from two institutions between November 2002 and February 2014 were reviewed. Formalin-fixed, paraffin-embedded tissue was stained with anti-PD-L1 (clone E1L3N). Cases showing more than 1% of tumor cells expression of PD-L1 were considered positive.

Results

PD-L1 was analyzed in 77 p with tumor tissue available and was positive in 20.7% p (14 samples in membrane, 16 in cytoplasm and 4 in immune infiltrate). PD-L1 intensity was weak in 56.2%, moderate in 25% and strong in 18.7% p. There was a significant relationship between PD-L1 expression and histology (PD-L1 expression 37.5% in no-epithelioid tumor and 13.2% in epithelioid; p=0.033). The median survival in p PD-L1 positive was 4.79 vs 16.3 months in p PD-L1 negative (p=0.012).

Conclusions

We have shown PD-L1 is expressed in 20% of patients, associated with no epithelioid histology and poor prognostic in MPM. Our results suggest PD-L1 warrants further exploration in selecting p for immunotherapy.     

CLEC1B Expression and PD-L1 Expression Predict Clinical Outcome in Hepatocellular Carcinoma with Tumor Hemorrhage

Spontaneous tumor hemorrhage (TH) is frequently observed in solid tumors including human hepatocellular carcinoma (HCC). TH implies fast-growing and worse tumor immunological microenvironment; however, the underlying mechanism remains largely unknown. CLEC1B is a signature gene highly associated with tumor progression. PD-L1 expression is a key biomarker predictive of immune checkpoint therapies, which showed astonishing effect on various types of tumor. We assume that, in HCC, TH may closely associate with the expression of these two molecules. In this study, 136 patients with HCC were enrolled. qRT-PCR showed that CLEC1B expression is significantly lower in HCC tumor tissue. Immunohistochemistry of HCC tissue microarrays demonstrated that PD-L1_high and CLEC1B_low expressions were significantly correlated with TH and clinicopathological features indicating worse HCC progression. According to univariate/multivariate analysis, a combination of PD-L1_high and CLEC1B_low expression was an independent prognostic factor indicating the poor outcome. The prognostic value of PD-L1_high and CLEC1B_low was validated by Cox proportional-hazard analyses. Collectively, tumor with TH is closely associated with CLEC1B_low & PD-L1_high expression, which may imply high response of PD-L1/PD-1 immune checkpoint therapies. CLEC1B may be a potential therapeutic target for PD-L1/PD-1 immunotherapy. PD-L1_high and CLEC1B_low can be a valuable prognosis factor implying worse clinical outcomes.     

宫颈癌组织中PD-L1的表达及临床意义分析

目的:探讨宫颈癌组织中程序性死亡因子配体(Programmed death ligand 1,PD-L1)的表达及临床意义,为宫颈癌免疫治疗提供理论和实验基础。方法:采用免疫组织化学染色的方法检测10例正常宫颈组织、71例宫颈上皮内瘤变(Cervical intraepithelial neoplasias,CIN)组织和89例宫颈癌组织中PD-L1蛋白的表达,分析PD-L1的表达与宫颈癌患者临床病理参数(临床分期、病理类型、年龄、淋巴转移)的相关性。结果:正常宫颈组织中无PD-L1表达,CIN中PD-L1表达的免疫评分低,呈弱阳性;宫颈癌中PD-L1表达的免疫评分高,呈强阳性。CIN和宫颈癌组织中PD-L1的阳性表达率分别为42%(30/41)和75%(66/89),其差异有统计学意义(P0.05)。PD-L1的表达与宫颈癌患者年龄、病理分级、淋巴转移无关(P0.05),而与患者临床分期显著相关(P=0.0021)。结论:PD-L1的表达上调可能参与了宫颈癌的发生和发展。     

Scapula alata in early breast cancer patients enrolled in a randomized clinical trial of post-surgery short-course image-guided radiotherapy

ABSTRACT: BACKGROUND: Scapula alata (SA) is a known complication of breast surgery associated with palsy of serratus anterior, but is seldom mentioned. We evaluated the risk factors associated with SA and the relationship of SA with ipsilateral shoulder/arm morbidity in a series of patients enrolled in a trial of post-surgery radiotherapy (RT). METHODS: The trial randomized women with completely resected stage I-II breast cancer to short-course image guided RT, vs. conventional RT. SA, arm volume and shoulder-arm mobility were measured prior to RT and at 1-3 months post-RT. Shoulder/arm morbidities were computed as post-RT percent change relatively to pre-RT measurements. RESULTS: Of 119 evaluable patients, 13 (=10.9%) had pre-RT SA. Age younger than 50 years old, body mass index less than 25 kg/m2, and axillary lymph node dissection, with odds ratios of 4.8 (P=0.009), 6.1 (P=0.016), and 6.1 (P=0.005), respectively. Randomization group was not significant. At 1-3 months post-RT, mean arm volume increased by 4.1% (P=0.036) and abduction decreased by 8.6% (P=0.046) among SA patients, but not among non SA patients. SA resolved in 8, persisted in 5, and appeared in 1 patient. CONCLUSION: Relationship of SA with lower body mass index suggests that SA might have been underestimated in overweight patients. Despite apparent resolution of SA in most patients, pre-RT SA portended an increased risk of shoulder/arm morbidity. We argue that SA warrants further investigation. Incidentally, the observation of SA occurring after RT in one patient represents the second case of post-RT SA reported in the literature.     

Recruiting monomer for dimer formation: resolving the antagonistic mechanisms of novel immune check point inhibitors against Programmed Death Ligand-1 in cancer immunotherapy

The design of small molecule antagonists against Programmed Death Ligand-1 (PD-L1) has been the recent highlight of the immune checkpoint blockade therapy. This interventive approach has been potentiated by the development of BMS compounds; BMS-1001 and BMS-1166, which exert their therapeutic activities by inducing dimerisation of PD-L1; a molecular mechanism that has remained unclear. For the first time, we resolve the dynamical events that underlie the antagonistic mechanisms of BMS-1001 and BMS-1166 when bound to PD-L1 using an all-atom molecular dynamics (MD) simulations approach and free binding energy Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) calculations. Time-scale dynamical findings revealed that upon binding a PD-L1 monomer, the BMS-compounds gradually facilitated the ‘inbound’ motion of another PD-L1 monomer in the same conformational phase space up till dimer formation. Moreover, the non-liganded PD-L1 monomer exhibited the highest structural flexibility and atomistic motions relative to the BMS-liganded monomer as revealed by post-MD trajectory analyses using root mean square deviation (RMSD) and root mean square fluctuations (RMSF) parameters. Trajectory investigations into ligand motions also revealed that the BMS compounds exhibited mechanistic transitions from the monomeric binding site (monomer A) where they were initially bound, to the second monomeric site (monomer B) where they were strongly bound, followed by eventual high-affinity interactions at the tunnel-like binding cleft formed upon the dimerisation of both PD-L1 monomers. These findings present a model that describes the mechanism by which the BMS compounds induce PD-L1 dimerisation and could further enhance the design of highly selective and novel monomeric recruiters of PD-L1 in cancer immunotherapy.