Programmed Cell Death Ligand 1 Checkpoint Research Articles

Tucatinib promotes immune activation and synergizes with programmed cell death-1 and programmed cell death-ligand 1 inhibition in HER2-positive breast cancer.

Programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) inhibitors have poor efficacy in patients with trastuzumab-resistant advanced HER2-positive breast cancer. Tucatinib is a potent, selective anti-HER2 tyrosine kinase inhibitor with proven clinical benefit in the advanced setting in patients with trastuzumab resistance. We investigated if tucatinib can alter the tumor microenvironment and if this could be harnessed for therapeutic efficacy. We investigated the antitumor efficacy and contribution of the immune response of tucatinib using 2 immunocompetent, HER2-positive murine breast cancer models (trastuzumab-sensitive H2N113; trastuzumab-resistant Fo5) and the efficacy of tucatinib with trastuzumab and PD-1 or PD-L1 checkpoint inhibitors. In both models, tucatinib statistically significantly inhibited tumor growth and demonstrated dose-dependent efficacy. Ex vivo analysis by flow cytometry of tumor-infiltrating lymphocytes in mice treated with tucatinib showed increased frequency, higher proliferation, and enhanced effector function of CD8+ effector memory T cells. Tucatinib treatment also increased frequency of CD8+PD-1+ and CD8+TIM3+ T cells, CD49+ natural killer cells, monocytes, and major histocompatibility complex II expression on dendritic cells and macrophages and a decrease in myeloid-derived suppressor cells. Gene expression analysis revealed statistically significant enrichment in pathways associated with immune activation, type I and II interferon response, adaptive immune response, and antigen receptor signaling. In vivo, tucatinib and α-PD-L1 or α-PD-1 demonstrated statistically significantly increased efficacy and improved survival of mice compared with tucatinib alone. Tucatinib modulates the immune microenvironment favorably, and combination treatment with α-PD-L1 or α-PD-1 demonstrated increased efficacy in preclinical HER2-positive tumor models. These findings provide a rationale for investigation of tucatinib and immune checkpoint inhibition in the clinic.

Dual TLR9 and PD-L1 targeting unleashes dendritic cells to induce durable antitumor immunity

BackgroundAlthough immune checkpoint inhibitors have been a breakthrough in clinical oncology, these therapies fail to produce durable responses in a significant fraction of patients. This lack of long-term efficacy may...

Total neoadjuvant treatment and PD-1/PD-L1 checkpoint inhibitor in locally advanced rectal cancer.

For local advanced rectal cancer (LARC), total neoadjuvant treatment (TNT) has shown more complete response (CR), reduced risk of distant metastasis (DM) and increase of the sphincter preservation rate. Now it is the one and only recommendation for high-risk group of LARC according to National Comprehensive Cancer Network (NCCN) rectal cancer guideline, while it is also preferentially recommended for low-risk group of LARC. TNT is also beneficial for distant rectal cancer patients who have need for organ preservation. Even though the prognostic value of programmed cell death-ligand 1 (PD-L1) in the neoadjuvant chemoradiotherapy (NACRT) of LARC patients is undetermined yet, the combination of NACRT and programmed cell death-1 (PD-1)/PD-L1 antibodies seem bring new hope for mismatch repair proficient (pMMR)/microsatellite stable (MSS) LARC patients. Accumulating small sample sized studies have shown that combining NACRT with PD-1/PD-L1 antibody yield better short-term outcomes for pMMR/MSS LARC patients than historic data. However, ideal total dose and fractionation of radiotherapy remains one of unresolved issues in this combination setting. Thorough understanding the impact of radiotherapy on the tumor microenvironment and their interaction is needed for in-depth understanding and exquisite design of treatments combination model.

PD-L1 expression as biomarker of efficacy of PD-1/PD-L1 checkpoint inhibitors in metastatic triple negative breast cancer: A systematic review and meta-analysis.

Inhibitors of programmed cell death 1 (PD-1)/programmed cell death ligand 1(PD-L1) checkpoint have been approved for metastatic triple negative breast cancer (mTNBC) in patients positive for PD-L1 expression. Negative results from the recent phase III trials (IMPassion131 and IMPassion132) have raises questions on the efficacy of PD-1/PD-L1 checkpoint inhibitors and the predictive value of PD-L1 expression. Here we attempt to systematically analyze the biomarker value of PD-L1 expression for predicting the response of PD-1/PD-L1 checkpoint inhibitors in mTNBC. PubMed database was searched until Dec 2021 for studies evaluating PD-1/PD-L1 checkpoint inhibitors plus/minus chemotherapy in mTNBC. Outcome of interest included objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). Review Manager (RevMan) version 5.4. was used for data-analysis. In total, 20 clinical trials comprising 3962 mTNBC patients (ICT: 2665 (67%); CT: 1297 (33%) were included in this study. Overall ORR was 22% (95%CI, 14-30%) and significant improvement was observed for PD-L1+ patients (ORR 1.78 [95%CI, 1.45-2.19], p<0.00001) as compared to PD-L1- cohort. Pooled outcome also indicated a significant 1-year PFS and 2-year OS advantage for patients with PD-L1 expression (1-year PFS: ORR 1.39 [95%CI, 1.04-1.85], p=0.02; I2 = 0%; 2-year OS: (ORR 2.47 [95%CI, 1.30-4.69], p=0.006; I2 = 63%). Subgroup analysis indicated that PD-L1 expression can successfully predict tumor response and 2-year OS benefit in mTNBC patients regardless of the type of investigating agent, line of treatment administration, and to some extent the type of treatment. Biomarker ability of PD-L1 expression to predict 1-year PFS was slightly better with pembrolizumab (p=0.09) than atezolizumab (p=0.18), and significantly better when treatment was administered in the first-line setting (OR 1.38 [95%CI, 1.02-1.87], p=0.04) and chemotherapy was added (OR 1.38 [95%CI, 1.02-1.86], p=0.03). Immune-related toxicity of any grade and grade≥3 was 39% (95%CI, 26%-52%) and 10% (95%CI, 8%-13%), respectively. PD-L1 expression can predict objective response rate and 2-year OS in mTNBC patients receiving PD-1/PD-L1 checkpoint inhibitors. One-year PFS is also predicted in selected patients. PD-L1 expression can be a useful biomarker of efficacy of PD-1/PD-L1 checkpoint inhibitors in mTNBC.

PD-L1 and MHC Class I Expression in High-grade Ovarian Cancers, Including Platinum-resistant Recurrences Treated With Checkpoint Inhibitor Therapy.

Immune-modulating therapies targeting the programmed cell death-1/programmed cell death ligand-1 (PD-L1) immunosuppressive system have been used successfully in many solid tumor types. There is evidence that biomarkers such as PD-L1 and major histocompatibility complex (MHC) class I help identify candidates for anti-programmed cell death-1/PD-L1 checkpoint inhibition, though the evidence is limited in ovarian malignancies. PD-L1 and MHC Class I immunostaining was performed on pretreatment whole tissue sections in 30 cases of high-grade ovarian carcinoma. The PD-L1 combined positive score was calculated (a score of ≥1 is considered positive). MHC class I status was categorized as an intact or subclonal loss. In patients who received immunotherapy, drug response was assessed using RECIST criteria. PD-L1 was positive in 26 of 30 cases (87%; combined positive score: 1 to 100). Seven of 30 patients showed subclonal loss of MHC class I (23%), and this occurred in both PD-L1 negative (3/4; 75%) and PD-L1 positive (4/26; 15%) cases. Only 1 of 17 patients who received immunotherapy in the setting of a platinum-resistant recurrence responded to the addition of immunotherapy, and all 17 died of disease. In the setting of recurrent disease, patients did not respond to immunotherapy regardless of PD-L1/MHC class I status, suggesting that these immunostains may not be effective predictive biomarkers in this setting. Subclonal loss of expression of MHC class I occurs in ovarian carcinoma, including in PD-L1 positive cases, suggesting that the 2 pathways of immune evasion may not be mutually exclusive and that it may be important to interrogate MHC class I status in PD-L1 positive tumors to identify additional immune evasion mechanisms in these tumors.

Inhibition of MYC suppresses programmed cell death ligand-1 expression and enhances immunotherapy in triple-negative breast cancer.

Cancer immunotherapy has emerged as a promising strategy against triple-negative breast cancer (TNBC). One of the immunosuppressive pathways involves programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1), but many patients derived little benefit from PD-1/PD-L1 checkpoint blockades treatment. Prior research has shown that MYC, a master transcription amplifier highly expressed in TNBC cells, can regulate the tumor immune microenvironment and constrain the efficacy of immunotherapy. This study aims to investigate the regulatory relationship between MYC and PD-L1, and whether a cyclin-dependent kinase (CDK) inhibitor that inhibits MYC expression in combination with anti-PD-L1 antibodies can enhance the response to immunotherapy. Public databases and TNBC tissue microarrays were used to study the correlation between MYC and PD-L1. The expression of MYC and PD-L1 in TNBCs was examined by quantitative real-time polymerase chain reaction and Western blotting. A patient-derived tumor xenograft (PDTX) model was used to evaluate the influence of a CDK7 inhibitor THZ1 on PD-L1 expression. Cell proliferation and migration were detected by 5-ethynyl-2'-deoxyuridine (EdU) cell proliferation and cell migration assays. Tumor xenograft models were established for in vivo verification. A high MYC expression level was associated with a poor prognosis and could alter the proportion of tumor-infiltrating immune cells (TIICs). The positive correlation between MYC and PD-L1 was confirmed by immunostaining samples from 165 TNBC patients. Suppression of MYC in TNBC caused a reduction in the levels of both PD-L1 messenger RNA and protein. In addition, antitumor immune response was enhanced in the TNBC cancer xenograft mouse model with suppression of MYC by CDK7 inhibitor THZ1. The combined therapy of CDK7 inhibitor THZ1 and anti-PD-L1 antibody appeared to have a synergistic effect, which might offer new insight for enhancing immunotherapy in TNBC.

Circ-HSP90A expedites cell growth, stemness, and immune evasion in non-small cell lung cancer by regulating STAT3 signaling and PD-1/PD-L1 checkpoint.

Circular RNAs (circRNAs) are important participators in tumor progression for their stable structure and high tissue-specific expression. The purpose of this research was to clarify the potential and mechanism of a novel circRNA-circ-HSP90A in non-small cell lung cancer (NSCLC). Biological potentials of circ-HSP90A in NSCLC were measured by functional assays. Molecular interaction was assessed by bioinformatics analysis and mechanical assays. Results depicted that circ-HSP90A was cyclization from its host gene heat shock protein 90 alpha (HSP90A) and was up-regulated in NSCLC cells. Circ-HSP90A depletion retarded proliferation, migration, invasion, and immune evasion. Mechanistically, circ-HSP90A recruited ubiquitin specific peptidase 30 (USP30) to stabilize HSP90A and then stimulated the signal transducer and activator of transcription 3 (STAT3) signaling. Meanwhile, circ-HSP90A sponged miR-424-5p to programmed cell death ligand 1 (PD-L1). Our study firstly showed that circ-HSP90A promoted cell growth, stemness, and immune evasion in NSCLC through regulating STAT3 signaling and programmed cell death 1 (PD-1)/PD-L1 checkpoint, mirroring that targeting circ-HSP90A might become a novel target of immunotherapy in NSCLC.

PD-1/PD-L1 Checkpoint Inhibitors Are Active in the Chicken Embryo Model and Show Antitumor Efficacy In Ovo.

Simple SummaryCancer immunotherapy, also known as immuno-oncology (IO), has made impressive progress in recent decades and is becoming an essential approach for cancer treatments. For IO drug development, a pertinent preclinical model is indispensable for the rapid and efficient transition from preclinical evaluation through to clinical progress. To date, rodents represent the most-often used models for preclinical evaluation. However, their use presents several drawbacks, including ethical constraints, and time-consuming and costly experiments, which could slow down IO drug development. The aim of our study was to assess the use of the chicken embryo (in ovo) model as an alternative in vivo model for evaluating IO drugs. We confirmed in ovo the anti-tumor efficacy of programmed cell death protein-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) checkpoint inhibitors based on the Chicken Chorioallantoic Membrane (CAM) assay, revealing the pertinence of the chicken embryo model in its use for IO research.(1) Purpose: To assess the use of the chicken embryo (in ovo) model as an alternative in vivo model for immuno-oncology (IO) drug development, focusing on programmed cell death protein-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) immune checkpoint inhibitors. (2) Methods: First, the presence of immune cells in the model was detected through the immunophenotyping of chicken peripheral blood mononuclear cells (PBMCs) based on fluorescence activated cell sorting (FACS) analysis and the immunohistochemistry (IHC) analysis of in ovo tumor-infiltrating lymphocytes. Second, the cross-reactivity between one anti-human PD-1 Ab, pembrolizumab (KEYTRUDA®), and chicken PD-1 was verified through the labelling of chicken splenocytes with pembrolizumab by FACS analysis. Third, the blockade effect of pembrolizumab on chicken PBMCs was assessed in vitro through cytotoxicity assay based on MTT. Fourth, the CAM assay was used to estimate the anti-tumor performance of pembrolizumab through the analyses of tumor growth and chicken immune cell infiltration in tumors. Finally, the efficacy of several PD-1 or PD-L1 inhibitors (nivolumab, atezolizumab and avelumab) on tumor growth was further assessed using the CAM assay. (3) Results: The presence of CD3+, CD4+, CD8+ T lymphocytes and monocytes was confirmed by FACS and IHC analyses. During in vitro assays, pembrolizumab cross-reacted with chicken lymphocytes and induced PD-1/PD-L1 blockade, which permitted the restoration of chicken T-cell’s cytotoxicity against human lung cancer H460 tumor cells. All these in vitro results were correlated with in ovo findings based on the CAM assay: pembrolizumab inhibited H460 tumor growth and induced evident chicken immune cell infiltration (with significant chicken CD45, CD3, CD4, CD8 and CD56 markers) in tumors. Furthermore, the potency of the CAM assay was not limited to the application of pembrolizumab. Nivolumab, atezolizumab and avelumab also led to tumor growth inhibition in ovo, on different tumor models. (4) Conclusions: The chicken embryo affords a physiological, immune reactive, in vivo environment for IO research, which allows observation of how the immune system defense against tumor cells, as well as the different immune tolerance mechanisms leading to tumor immune escape. The encouraging results obtained with PD-1/PD-L1 inhibitors in this study reveal the potential use of the chicken embryo model as an alternative, fast, and reliable in vivo model in the different fields of IO drug discovery.

Analysis of the Role and Mechanism of ZEB1 in Regulating Cervical Carcinoma Progression via Modulating PD-1/PD-L1 Checkpoint.

Background Cervical carcinoma (CC) is a common and highly malignant tumor in women. The involvement of zinc finger E-box binding homeobox 1 (ZEB1) in many kinds of tumors has been well-documented; however, its role and mechanism in CC remain to be clarified. Objective This study investigated the mechanism of ZEB1 in modulating the growth and metastasis of CC cells. Methods The expression of ZEB1 in CC tissues and adjacent normal counterparts was determined by reverse transcription-polymerase chain reaction (RT-PCR). The correlation between ZEB1 and patient clinicopathological indexes was analyzed. In vitro, gain and loss functions of ZEB1 were performed in C-33A and HeLa cell lines. The proliferation, migration, and invasion of CC cells were detected by Cell Counting Kit-8 (CCK-8) assay and transwell assay, respectively. The expression levels of apoptosis-related proteins such as BCL2-associated X (Bax), B-cell lymphoma-2 (Bcl2), and Caspase-3, as well as epithelial-mesenchymal transition (EMT)-associated proteins including E-cadherin, Vimentin, and Snail, were measured by Western blotting. In addition, the targeting relationship between ZEB1 and programmed death 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) was predicted by bioinformatics and further verified by dual-luciferase reporter assay. Results ZEB1 was significantly up-regulated in CC tissues compared with normal counterparts. ZEB1 overexpression promoted the migration, proliferation, and invasion of CC cells and inhibited apoptosis, while knocking down ZEB1 contributed to the opposite effects. In addition, experiments on related mechanisms confirmed that ZEB1 targeted the 3'EUTR terminal of PD-1/PD-L1 and negatively regulated its expression. And an interaction between ZEB1 and PD-1/PD-L1 was identified. Conclusion ZEB1 can promote the proliferation and metastasis of CC cells via modulating the PD-1/PD-L1 checkpoint.

B7-1 and programmed cell death-ligand 1 in primary and lymph node metastasis lesions of non-small cell lung carcinoma.

BackgroundProgrammed cell death ligand 1 (PD‐L1) status has been reported to be different between metastatic and primary lesions in some cases. Therefore, the interaction between carcinoma and immune cells could influence their expression in the tumor microenvironment. PD‐L1 is known to bind not only to Programmed cell death 1 (PD‐1) but also to B7‐1 (CD80). In this study, we examined the interaction between lung carcinoma cell lines and peripheral blood mononuclear cells (PBMCs) in vitro. We then examined the significance of B7‐1 expression non‐small cell lung cancer (NSCLC) microenvironment.MethodsThe interaction of lung carcinoma cell lines and PBMC through the soluble factors was analyzed using a co‐culture system. The changes in expression of immune checkpoint‐related factors in PBMC were examined by PD‐1/PD‐L1 Checkpoint Pathway qPCR Array Kit. B7‐1 expression in NSCLC tissues was examined by immunohistochemistry.ResultsB7‐1 was upregulated following the co‐culture with the lung carcinoma cell lines. B7‐1 expression in NSCLC tissues was significantly higher in smokers and squamous cell carcinomas and was significantly positively correlated with PD‐L1 status in primary cancer. However, B7‐1 and PD‐1 were not correlated between primary and metastatic diseases in the same patients.ConclusionPD‐1 inhibitors inhibited PD‐1/PD‐L1 binding but not PD‐L1/B7‐1 binding. These results demonstrated that the intratumoral ratio of B7‐1 positive T cells in NSCLC tissue could be involved in the therapeutic efficacy of PD‐L1 inhibitors. This study focused on lymph node metastasis but other sites of distant metastases should be explored by further analysis.

NIR-II Fluorescent Molecular Bottlebrush Prepared by Ring-Opening Polymerization for Programmed Cell Death Ligand-1 Checkpoint Imaging

In the area of tumor therapy, the immune checkpoint drugs programmed death-1 receptor (PD-1) and programmed death-ligand 1 (PD-L1) have been widely used in clinical trials and shown excellent thera...

Effects of a Novel Thiadiazole Derivative with High Anticancer Activity on Cancer Cell Immunogenic Markers: Mismatch Repair System, PD-L1 Expression, and Tumor Mutation Burden.

Microsatellite instability (MSI), tumor mutation burden (TMB), and programmed cell death ligand-1 (PD-L1) are particularly known as immunotherapy predictive biomarkers. MSI and TMB are closely related to DNA mismatch repair (MMR) pathway functionality, while the PD-L1 checkpoint mediates cancer cell evasion from immune surveillance via the PD-L1/PD-1 axis. Among all the novel triazolo[3,4-b]thiadiazole derivatives, the compound KA39 emerged as the most potent anticancer agent. In the present study, potential alterations in MSI, TMB, and/or PD-L1 expression upon cell treatment with KA39 are explored. We tested three MMR-deficient (DLD-1, LS174T, and DU-145) and two MMR-proficient (HT-29 and PC-3) human cancer cell lines. Our findings support KA39-induced PD-L1 overexpression in all cancer cell lines, although the most outstanding increase was observed in MMR-proficient HT-29 cells. MSI analysis showed that KA39 affects the MMR system, impairing its recognition or repair activity, particularly in MMR-deficient DLD-1 and DU-145 cells, enhancing oligonucleotide production. There were no remarkable alterations in the TMB between untreated and treated cells, indicating that KA39 does not belong to mutagenic agents. Taking together the significant in vitro anticancer activity with PD-L1 upregulation and MSI increase, KA39 should be investigated further for its implication in chemo-immunotherapy of cancer.

Co-delivery of IOX1 and doxorubicin for antibody-independent cancer chemo-immunotherapy

Anti-programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) antibodies are currently used in the clinic to interupt the PD-1/PD-L1 immune checkpoint, which reverses T cell dysfunction/exhaustion and shows success in treating cancer. Here, we report a histone demethylase inhibitor, 5-carboxy-8-hydroxyquinoline (IOX1), which inhibits tumour histone demethylase Jumonji domain-containing 1A (JMJD1A) and thus downregulates its downstream β-catenin and subsequent PD-L1, providing an antibody-independent paradigm interrupting the PD-1/PD-L1 checkpoint. Synergistically, IOX1 inhibits cancer cells’ P-glycoproteins (P-gp) through the JMJD1A/β-catenin/P-gp pathway and greatly enhances doxorubicin (DOX)-induced immune-stimulatory immunogenic cell death. As a result, the IOX1 and DOX combination greatly promotes T cell infiltration and activity and significantly reduces tumour immunosuppressive factors. Their liposomal combination reduces the growth of various murine tumours, including subcutaneous, orthotopic, and lung metastasis tumours, and offers a long-term immunological memory function against tumour rechallenging. This work provides a small molecule-based potent cancer chemo-immunotherapy.

A narrative review of immune checkpoint inhibitors in early stage triple negative breast cancer

: Triple negative breast cancer (TNBC) is an aggressive disease characterized by heterogeneous molecular and immunological characteristics that portends worse overall survival compared to other breast cancer subtypes. Until now, chemotherapy has remained the cornerstone of TNBC treatment despite recent efforts to explore new molecularly targeted therapeutic targets and personalized treatments. Given TNBC has a more immunogenic tumor microenvironment than other breast cancer subtypes, there is hope that immunotherapy will emerge as a new pillar of treatment in TNBC. Based on the IMPASSION130 and KEYNOTE-355 studies, the combination of nab-paclitaxel plus atezolizumab, and chemotherapy plus pembrolizumab, respectively, have been approved by the Food and Drug Administration for locally recurrent, unresectable, or metastatic TNBC in the first line setting. Several studies have now been published demonstrating programmed cell death-1 protein (PD-1)/programmed cell death ligand 1 (PD-L1) inhibitors given alongside neoadjuvant taxane and anthracycline-based chemotherapy with or without a platinum agent significantly improves pathologic complete response rate. The choice of chemotherapy given in cooperation with PD-1/PD-L1 checkpoint inhibitor seems to determine the amount benefit derived from immunotherapy. However, longer term follow-up is required to ascertain whether immunotherapy, specifically PD-1/PD-L1 blockade, will improve event-free survival and overall survival. Future studies are underway investigating the role of immunotherapy in the adjuvant setting and in patients with residual disease after neoadjuvant therapy. Other unanswered questions remain including the total duration of immunotherapy, and which patient population would benefit from these expensive and sometimes toxic therapies. This narrative review aims to provide insight on the current landscape of immune checkpoint inhibitors in early TNBC.

Abstract B39: Changes in the number of residual circulating epithelial tumor cells (CETCs) and their programmed cell death ligand 1 (PD-L1) status during radiotherapy in breast cancer patients

Abstract Background: Preclinical studies have suggested that radiotherapy (RT) followed by immunotherapy could be a promising strategy for synergistic enhancement of treatment efficacy. RT induces immunogenic changes in cancer cells that can lead to adaptive upregulation of PD-L1 expression. Moreover, RT not only reduces local recurrence but also improves overall survival by preventing distant metastases, which indicates its influence on the remaining occult tumor, such as circulating tumor cells. For this reason, the aim of this study was to determine the PD-L1 status on CETCs before and during RT. Methods: CETCs were determined in 54 primary breast cancer patients in early and locally advanced stages. The number of CETCs and their expression of PDL-L1 were investigated using the maintrac method. The fraction of PD-L1 positive CETCs was assessed prior to (baseline), 3 and 6 weeks after the start of RT. Results: We found a correlation between the PD-L1 status of CETCs and aggressiveness of cancer disease prior to radiotherapy. Patients with positive lymph node status presented more PD-L1 positive CETCs compared to patients with negative lymph nodes (mean 73% vs. 50%, p&amp;lt;0.01). Moreover, the HER2 expression of the primary tumor was also positively correlated with PD-L1 expression. Lower numbers of CETCs were detected in patients who had not received chemotherapy or adjuvant chemotherapy before RT than in those who received neoadjuvant chemotherapy (median 20 vs. 25 vs. 120 CETC/100μL blood, p&amp;lt;0.001). Surprisingly, the fraction of PD-L1 positive CETCs decreased during radiotherapy only in patients who had received neoadjuvant chemotherapy. Conclusion: Although the number of CETCs and the fraction of PD-L1 positive CETCs were higher in patients who had received neoadjuvant chemotherapy, radiotherapy reduced both measured biomarkers. In the future PD-1/PD-L1 checkpoint inhibitors after radiotherapy might have additional benefit in breast cancer patients. Citation Format: Dorothea Schott, Monika Pizon, Katharina Pachmann, Ulrich Pachmann, Matthias Maeurer. Changes in the number of residual circulating epithelial tumor cells (CETCs) and their programmed cell death ligand 1 (PD-L1) status during radiotherapy in breast cancer patients [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B39.

Abstract P4-01-14: Influence of radiotherapy on residual circulating epithelial tumor cells (CETCs) and their programmed cell death ligand 1 (PD-L1) status in breast cancer patients

Abstract Background: Preclinical studies have suggested that radiotherapy followed by immunotherapy could be a promising strategy for synergistic enhancement of treatment efficacy. Radiation induces immunogenic changes in cancer cells which can lead to adaptive up-regulation of PD-L1 expression. Moreover, radiotherapy reduces not only local recurrence but even more distant relapse indicating its influence also on the residual occult tumor such as circulating tumor cells. For this reason the aim of this study was to determine the PD-L1 status on CETCs before and during radiotherapy. Methods: CETCs were determined in 54 primary breast cancer patients in early and locally advanced stages. The number of CETCs and their expression of PDL-L1 were investigated using the maintrac method. The fraction of PD-L1 positive CETCs was assessed prior to (baseline), 3 and 6 weeks after the start of radiotherapy. Results: We found an association between the PD-L1 status on CETCs and aggressiveness of cancer disease before radiotherapy. Patients with positive lymph node status had more PD-L1 positive CETCs as compared to patients with negative lymph nodes (mean 73 vs. 50, p&amp;lt;0.01). HER2 expression of the primary tumor was also positively correlated with PD-L1 expression. Lower numbers of CETCs were detected in patients who had not received chemotherapy or adjuvant chemotherapy before radiation than in those who received neoadjuvant chemotherapy (median 20 vs 25 vs 120 CETC/100µl blood, p&amp;lt;0.001). Surprisingly, the fraction of PD-L1 positive CETC decreased during radiotherapy only in patients who had received neoadjuvant chemotherapy. Conclusion: The number of CETCs and the fraction of PD-L1 positive CETCs were higher in patients who had received neoadjuvant chemotherapy and radiotherapy reduced both measured biomarkers. In the future PD-1/PD-L1 checkpoint inhibitors after radiotherapy might have additional benefit in breast cancer patients. Citation Format: Dorothea Schott, Monika Pizon, Ulrich Pachmann, Katharina Pachmann, Matthias Mäurer. Influence of radiotherapy on residual circulating epithelial tumor cells (CETCs) and their programmed cell death ligand 1 (PD-L1) status in breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-01-14.

Mycobacterial infections due to PD-1 and PD-L1 checkpoint inhibitors

BackgroundImmune checkpoint inhibitors that block programmed cell death-1 (PD-1) and programmed cell death ligand-1 (PD-L1) have improved outcomes for many cancer subtypes but do exhibit toxicity, in the form of immune-related adverse events.ObjectiveThe aim of this study was to investigate the emerging toxicities of PD-1 and PD-L1 inhibitors including acute or reactivation of tuberculosis (TB) and atypical mycobacterial infection (AMI).MethodsThis study was completed as a retrospective review using the US Food and Drug Administration Adverse Events Reporting System (FAERS) for incidence of TB and AMI due to PD-1 and PD-L1 inhibitors compared with other FDA (Food and Drug Administration) approved drugs. The statistical methods included disproportionality signal analysis using the reporting OR (ROR) to compare cases. The 95% Wald CI was reported to assess the precision of the ROR.ResultsOut of the 10 146 481 adverse events (AEs) reported to FAERS for all drugs between 1 January 2015 and 31 March 2020, 73 886 AEs were due to the five FDA approved PD-1/PD-L1 inhibitors. Seventy-two cases of TB were due to PD-1/PD-L1 inhibitors. Specifically, 45 cases (62.5%) due to nivolumab, 18 (25%) due to pembrolizumab, 5 (7%) due to atezolizumab and 4 (5.5%) due to durvalumab. There were 13 cases of AMI: 9 (69.3%) due to nivolumab, 2 (15.3%) due to pembrolizumab and 1 (7.7%) each due to durvalumab and atezolizumab. Avelumab was not attributed to any AE of TB or AMI. From analysis of the FAERS database, the calculated ROR for TB due to PD-1/PD-L1 inhibitors was 1.79 (95% CI, 1.42 to 2.26) (p<0.0001) and for AMI was 5.49 (95% CI, 3.15 to 9.55) (p<0.0001).ConclusionPD-1/PD-L1 inhibitors used in the treatment of cancer subtypes is associated with increased TB and AMI risk. Although this complication is rare, clinicians using PD-1/PD-L1 inhibitors should be aware of the risks.

Predictive Factors for Response to PD-1/PD-L1 Checkpoint Inhibition in the Field of Hepatocellular Carcinoma: Current Status and Challenges.

Immunotherapies targeting immune checkpoints are fast-developing therapeutic approaches adopted for several tumor types that trigger unprecedented rates of durable clinical responses. Immune checkpoint programmed cell death protein 1 (PD-1), expressed primarily by T cells, and programmed cell death ligand 1 (PD-L1), expressed mainly by tumor cells, macrophages, and dendritic cells, are molecules that impede immune function, thereby allowing tumor cells to proliferate, grow and spread. PD-1/PD-L1 checkpoint inhibitors have emerged as a promising treatment strategy of hepatocellular carcinoma (HCC). However, only a minority of HCC patients benefit from this therapy. To find a niche for immune checkpoint inhibition in HCC patients, future strategies might require predictive factor-based patient selection, to identify patients who are likely to respond to the said therapy and combination strategies in order to enhance anti-tumor efficacy and clinical success. This review provides an overview of the most recent data pertaining to predictive factors for response to PD-1/PD-L1 checkpoint inhibition in the field of HCC.

Fit-For-Purpose PD-L1 Biomarker Testing For Patient Selection in Immuno-Oncology: Guidelines For Clinical Laboratories From the Canadian Association of Pathologists-Association Canadienne Des Pathologistes (CAP-ACP).

Since 2014, programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) checkpoint inhibitors have been approved by various regulatory agencies for the treatment of multiple cancers including melanoma, lung cancer, urothelial carcinoma, renal cell carcinoma, head and neck cancer, classical Hodgkin lymphoma, colorectal cancer, gastroesophageal cancer, hepatocellular cancer, and other solid tumors. Of these approved drug/disease combinations, a subset also has regulatory agency-approved, commercially available companion/complementary diagnostic assays that were clinically validated using data from their corresponding clinical trials. The objective of this document is to provide evidence-based guidance to assist clinical laboratories in establishing fit-for-purpose PD-L1 biomarker assays that can accurately identify patients with specific tumor types who may respond to specific approved immuno-oncology therapies targeting the PD-1/PD-L1 checkpoint. These recommendations are issued as 38 Guideline Statements that address (i) assay development for surgical pathology and cytopathology specimens, (ii) reporting elements, and (iii) quality assurance (including validation/verification, internal quality assurance, and external quality assurance). The intent of this work is to provide recommendations that are relevant to any tumor type, are universally applicable and can be implemented by any clinical immunohistochemistry laboratory performing predictive PD-L1 immunohistochemistry testing.

Comparison of Biomarker Modalities for Predicting Response to PD-1/PD-L1 Checkpoint Blockade

PD-L1 (programmed cell death ligand 1) immunohistochemistry (IHC), tumor mutational burden (TMB), gene expression profiling (GEP), and multiplex immunohistochemistry/immunofluorescence (mIHC/IF) assays have been used to assess pretreatment tumor tissue to predict response to anti-PD-1/PD-L1 therapies. However, the relative diagnostic performance of these modalities has yet to be established. To compare studies that assessed the diagnostic accuracy of PD-L1 IHC, TMB, GEP, and mIHC/IF in predicting response to anti-PD-1/PD-L1 therapy. A search of PubMed (from inception to June 2018) and 2013 to 2018 annual meeting abstracts from the American Association for Cancer Research, American Society of Clinical Oncology, European Society for Medical Oncology, and Society for Immunotherapy of Cancer was conducted to identify studies that examined the use of PD-L1 IHC, TMB, GEP, and mIHC/IF assays to determine objective response to anti-PD-1/PD-L1 therapy. For PD-L1 IHC, only clinical trials that resulted in US Food and Drug Administration approval of indications for anti-PD-1/PD-L1 were included. Studies combining more than 1 modality were also included. Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines were followed. Two reviewers independently extracted the clinical outcomes and test results for each individual study. Summary receiver operating characteristic (sROC) curves; their associated area under the curve (AUC); and pooled sensitivity, specificity, positive and negative predictive values (PPV, NPV), and positive and negative likelihood ratios (LR+ and LR-) for each assay modality. Tumor specimens representing over 10 different solid tumor types in 8135 patients were assayed, and the results were correlated with anti-PD-1/PD-L1 response. When each modality was evaluated with sROC curves, mIHC/IF had a significantly higher AUC (0.79) compared with PD-L1 IHC (AUC, 0.65, P < .001), GEP (AUC, 0.65, P = .003), and TMB (AUC, 0.69, P = .049). When multiple different modalities were combined such as PD-L1 IHC and/or GEP + TMB, the AUC drew nearer to that of mIHC/IF (0.74). All modalities demonstrated comparable NPV and LR-, whereas mIHC/IF demonstrated higher PPV (0.63) and LR+ (2.86) than the other approaches. In this meta-analysis, tumor mutational burden, PD-L1 IHC, and GEP demonstrated comparable AUCs in predicting response to anti-PD-1/PD-L1 treatment. Multiplex immunohistochemistry/IF and multimodality biomarker strategies appear to be associated with improved performance over PD-L1 IHC, TMB, or GEP alone. Further studies with mIHC/IF and composite approaches with a larger number of patients will be required to confirm these findings. Additional study is also required to determine the most predictive analyte combinations and to determine whether biomarker modality performance varies by tumor type.