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Pembrolizumab (PD-1 inhibitor) and cetuximab (EGFR inhibitor) are active as single agents and in combination with cytotoxic chemotherapy for recurrent or metastatic head and neck squamous cell carcinoma (HNSCC). Given each drug's single agent activity and unique mechanism of action, we aimed to evaluate the anti-tumour activity of PD-1 blockade with EGFR inhibition in recurrent or metastatic HNSCC. This study is an open-label, non-randomised, multi-arm, phase 2 trial done at four academic centres in the USA. Participants were required to have platinum-resistant or platinum-ineligible, recurrent or metastatic HNSCC, be at least 18 years old, have an Eastern Cooperative Oncology Group performance status 0–1, have measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, and to have received no previous immunotherapy or EGFR inhibition. All participants received pembrolizumab 200 mg intravenously every 3 weeks, combined with an initial loading dose of cetuximab 400 mg/m2 intravenously followed by 250 mg/m2 intravenously weekly (21 day cycle). The primary endpoint was overall response rate defined as the proportion of participants with a partial or complete responses (per RECIST version 1.1) by 6 months in the intention-to-treat population. The safety population included all participants who received at least one dose of pembrolizumab. Herein, the final analysis of cohort 1 (no previous PD-1, PD-L1, or EGFR inhibition for recurrent or metastatic HNSCC) is reported. Three additional cohorts (two for participants with a previous response to immunotherapy followed by relapse or progression, with or without previous cetuximab exposure, and one for cutaneous HNSCC) will be reported separately once fully accrued. This study is registered with ClinicalTrials.gov, NCT03082534, and remains open as the three additional cohorts are actively accruing participants. Between March 22, 2017, and July 16, 2019, 33 participants were enrolled to cohort 1. All 33 participants received at least one dose of pembrolizumab. Median follow-up duration was 7·3 months (IQR 3·9–10·9). By 6 months, the overall response rate was 45% (95% CI 28–62), with 15 of 33 participants achieving a partial response. The most common grade 3–4 treatment-related adverse event was oral mucositis (three [9%] of 33 participants), and serious treatment-related adverse events occurred in five (15%) participants. No treatment-related deaths occurred. Pembrolizumab combined with cetuximab shows promising clinical activity for recurrent or metastatic HNSCC, and merits further investigation. Merck Sharp & Dohme.

PD-1 and PD-L1 act to restrict T cell responses in cancer and contribute to self-tolerance. Consistent with this role, PD-1 checkpoint inhibitors have been associated with immune-related adverse events (irAEs), immune toxicities thought to be autoimmune in origin. Analyses of dermatological irAEs have identified an association with improved overall survival (OS) following anti–PD-(L)1 therapy, but the factors that contribute to this relationship are poorly understood. We collected germline whole-genome sequencing data from IMvigor211, a recent phase 3 randomized controlled trial comparing atezolizumab (anti–PD-L1) monotherapy to chemotherapy in bladder cancer. We found that high vitiligo, high psoriasis, and low atopic dermatitis polygenic risk scores (PRSs) were associated with longer OS under anti–PD-L1 monotherapy as compared to chemotherapy, reflecting the Th17 polarization of these diseases. PRSs were not correlated with tumor mutation burden, PD-L1 immunohistochemistry, nor T-effector gene signatures. Shared genetic factors impact risk for dermatological autoimmunity and anti–PD-L1 monotherapy in bladder cancer.

Multiple Sclerosis (MS) is a chronic autoimmune inflammatory disorder of the central nervous system (CNS). Current therapies mainly target inflammatory processes during acute stages, but effective treatments for progressive MS are limited. In this context, astrocytes have gained increasing attention as they have the capacity to drive, but also suppress tissue-degeneration. Here we show that astrocytes upregulate the immunomodulatory checkpoint molecule PD-L1 during acute autoimmune CNS inflammation in response to aryl hydrocarbon receptor and interferon signaling. Using CRISPR-Cas9 genetic perturbation in combination with small-molecule and antibody-mediated inhibition of PD-L1 and PD-1 both in vivo and in vitro, we demonstrate that astrocytic PD-L1 and its interaction with microglial PD-1 is required for the attenuation of autoimmune CNS inflammation in acute and progressive stages in a mouse model of MS. Our findings suggest the glial PD-L1/PD-1 axis as a potential therapeutic target for both acute and progressive MS stages. Co-inhibitory signaling controls immune mechanisms in health and disease. The authors here show that in autoimmune neuroinflammation, astrocytic PD-L1 mitigates autoimmune neuroinflammation through interaction with PD1 expressing microglia.

Background Regulatory T cells (Tregs) play an important role in the antitumor immune response in epithelial ovarian cancer (EOC). To understand the immune-inhibitory networks of EOC, we addressed the association between Tregs and immune checkpoint expression on T cells in the tumor microenvironment of EOC. Methods A total of 41 patients with stage IIIC and IV EOC were included in the analysis. We harvested cells from malignant ascites and investigated them using multi-color flow cytometry. We categorized the Tregs into 3 groups: effector-type Tregs, naïve Tregs and non-Tregs, based on the expression patterns of CD45RA and Foxp3 in CD4 + T cells. Furthermore, the relationships between the expression of various immune checkpoint molecules, such as PD-1, on CD8 + T cells and each of the Treg subtypes was also evaluated. Results The median frequency of naïve Tregs, effector-type Tregs and non-Tregs were 0.2% (0–0.8), 2.0% (0–11.4) and 1.5% (0.1–6.3) in CD4 + T cells of malignant ascites from EOC patients, respectively. A high frequency of effector-type Tregs was associated with high-grade serous carcinoma compared with the other histotypes. Patients with higher proportions of effector-type Tregs showed a trend towards increased progression-free survival. We also demonstrated a correlation between a higher proportion of effector-type Tregs and increased PD-1 expression on CD8 + T cells. In addition, C–C chemokine receptor 4 expression was also observed in effector-type Tregs. Conclusion These data suggest that multiple immune-inhibitory networks exist in malignant ascites from EOC patients, suggesting an approach towards combinational immunotherapies for advanced EOC patients.

Patients with chronic hepatitis B (CHB) undergoing interferon (IFN)-α-based therapies often exhibit a poor HBeAg serological response. Thus, there is an unmet need for new therapies aimed at CHB. This study comprised two clinical trials, including 130 CHB patients, who were treatment-naïve; in the first, 92 patients were systematically analyzed ex vivo for interleukin-2 receptor (IL-2R) expression and inhibitory molecules expression after receiving Peg-IFN-α-2b therapy. In our second clinical trial, 38 non-responder patients, in whom IFN-α therapy had failed, were treated with or without low-dose IL-2 for 24 weeks. We then examined the hepatitis B virus (HBV)-specific CD8 + T-cell response and the clinical outcome, in these patients. Although the majority of the participants undergoing Peg-IFN-α-2b therapy were non-responders, we observed a decrease in CD25 expression on their CD4 + T cells, suggesting that IFN-α therapy may provide a rationale for sequential IL-2 treatment without increasing regulatory T cells (Tregs). Following sequential therapy with IL-2, we demonstrated that the non-responders experienced a decrease in the numbers of Tregs and programmed cell death protein 1 (PD-1) expression. In addition, sequential IL-2 administration rescued effective immune function, involving signal transducer and activator of transcription 1 (STAT1) activation. Importantly, IL-2 therapy significantly increased the frequency and function of HBV-specific CD8 + T cells, which translated into improved clinical outcomes, including HBeAg seroconversion, among the non-responder CHB patients. Our findings suggest that sequential IL-2 therapy shows efficacy in rescuing immune function in non-responder patients with refractory CHB.

The identification of predictors for immunotherapy is often hampered by the absence of control groups in many studies, making it difficult to distinguish between prognostic and predictive biomarkers. This study presents biomarker analyses from the phase 3 CONTINUUM trial (NCT03700476), the first to show that adding anti-PD-1 (aPD1) to chemoradiotherapy (CRT) improves event-free survival (EFS) in patients with locoregionally advanced nasopharyngeal carcinoma. A dynamic single-cell atlas was profiled using mass cytometry on peripheral blood mononuclear cell samples from 12 pairs of matched relapsing and non-relapsing patients in the aPD1-CRT arm. Using a supervised representation learning algorithm, we identified a Ki67 + proliferating regulatory T cells (Tregs) population expressing high levels of activated and immunosuppressive molecules including FOXP3, CD38, HLA-DR, CD39, and PD-1, whose abundance correlated with treatment outcome. The frequency of these Ki67 + Tregs was significantly higher at baseline and increased during treatment in patients who relapsed compared to non-relapsers. Further validation through flow cytometry ( n  = 120) confirmed the predictive value of this Treg subset. Multiplex immunohistochemistry ( n  = 249) demonstrated that Ki67 + Tregs in tumors could predict immunotherapy benefit, with aPD1 improving EFS only in patients with low baseline levels of Ki67 + Tregs. These findings were further validated in the multicenter phase 3 DIPPER trial ( n  = 262, NCT03427827) and the phase 3 OAK trial of anti-PD-L1 immunotherapy in NSCLC, underscoring the predictive value of Ki67 + Treg frequency in identifying the beneficiaries of immunotherapy and potentially guiding personalized treatment strategies.

PD-1/PD-L1 might have a causal role in operating lung cancer risk. However, such an association has not been investigated in the general population. We assessed whether PD-L1 has an independent effect on lung cancer risk using two-sample Mendelian randomization (MR) based on a proteomic genome-wide association study (3301 health participants) of European ancestry and the International Lung cancer Consortium (11,348 cases and 15,861 controls). Negative control analyses using chronic obstructive pulmonary disease (COPD)/asthma/interstitial lung disease (ILD)-related infection (~ 22,730 cases and ~ 112,908 controls) were also conducted to enhance the credibility of the selected instruments and MR-based estimates. This study found that genetically predicted PD-1/PD-L1 were not significantly associated with lung cancer after adjustment for multiplicity. However, suggestive evidence was observed for the total effect of higher PD-1 with decreased lung cancer risk and the direct effect (i.e., not mediated by PD-1 and smoking) of lower PD-L1 with decreased lung cancer risk. No association between genetically predicted PD-L1 and COPD/asthma/ILD related infection was noted. Taken together, our findings suggest that interventions decreasing PD-L1 might have a role in lowering lung cancer risk.

T cell Ig and ITIM domain (TIGIT) is an inhibitory receptor expressed by activated T cells, Tregs, and NK cells. Here, we determined that TIGIT is upregulated on tumor antigen-specific (TA-specific) CD8⁺ T cells and CD8⁺ tumor-infiltrating lymphocytes (TILs) from patients with melanoma, and these TIGIT-expressing CD8⁺ T cells often coexpress the inhibitory receptor PD-1. Moreover, CD8⁺ TILs from patients exhibited downregulation of the costimulatory molecule CD226, which competes with TIGIT for the same ligand, supporting a TIGIT/CD226 imbalance in metastatic melanoma. TIGIT marked early T cell activation and was further upregulated by T cells upon PD-1 blockade and in dysfunctional PD-1⁺TIM-3⁺ TA-specific CD8⁺ T cells. PD-1⁺TIGIT⁺, PD-1⁻TIGIT⁺, and PD-1⁺TIGIT⁻ CD8⁺ TILs had similar functional capacities ex vivo, suggesting that TIGIT alone, or together with PD-1, is not indicative of T cell dysfunction. However, in the presence of TIGIT ligand-expressing cells, TIGIT and PD-1 blockade additively increased proliferation, cytokine production, and degranulation of both TA-specific CD8⁺ T cells and CD8⁺ TILs. Collectively, our results show that TIGIT and PD-1 regulate the expansion and function of TA-specific CD8⁺ T cells and CD8⁺ TILs in melanoma patients and suggest that dual TIGIT and PD-1 blockade should be further explored to elicit potent antitumor CD8⁺ T cell responses in patients with advanced melanoma.

Structural variations disrupting the 3′ region of PD-L1 are shown to aid immune evasion in a number of human cancers, including adult T-cell leukaemia/lymphoma, and in a mouse tumour model, CRISPR/Cas9-mediated deletion of the 3'-UTR of Pd-l1 is also shown to result in immune escape, suggesting that PD-L1 3′-UTR disruption could provide a diagnostic marker to identify patients who will benefit from anti-PD-1/PD-L1 therapy. A marker for responsiveness to anti-PD-1/PD-L1 therapy In some patients, cancer therapy with antibodies against programmed cell death 1 (PD-1) and its ligand (PD-L1) is ineffective due to immune evasion. Here Seishi Ogawa and colleagues show that structural variations disrupting the 3′-region of PD-L1 lead to overexpression of the PD-L1 protein, promoting immune evasion in a number of human cancers, including adult T-cell leukaemia and diffuse large B-cell lymphoma. Crispr-Cas9-mediated deletion of the 3′-UTR of Pd-l1 is also shown to result in immune escape in a mouse tumour model, suggesting that PD-L1 3′-UTR disruption could provide a diagnostic marker to identify patients who will benefit from anti-PD-1/PD-L1 therapy. Successful treatment of many patients with advanced cancer using antibodies against programmed cell death 1 (PD-1; also known as PDCD1) and its ligand (PD-L1; also known as CD274) has highlighted the critical importance of PD-1/PD-L1-mediated immune escape in cancer development 1 , 2 , 3 , 4 , 5 , 6 . However, the genetic basis for the immune escape has not been fully elucidated, with the exception of elevated PD-L1 expression by gene amplification and utilization of an ectopic promoter by translocation, as reported in Hodgkin and other B-cell lymphomas, as well as stomach adenocarcinoma 6 , 7 , 8 , 9 , 10 . Here we show a unique genetic mechanism of immune escape caused by structural variations (SVs) commonly disrupting the 3′ region of the PD-L1 gene. Widely affecting multiple common human cancer types, including adult T-cell leukaemia/lymphoma (27%), diffuse large B-cell lymphoma (8%), and stomach adenocarcinoma (2%), these SVs invariably lead to a marked elevation of aberrant PD-L1 transcripts that are stabilized by truncation of the 3′-untranslated region (UTR). Disruption of the Pd-l1 3′-UTR in mice enables immune evasion of EG7-OVA tumour cells with elevated Pd-l1 expression in vivo , which is effectively inhibited by Pd-1/Pd-l1 blockade, supporting the role of relevant SVs in clonal selection through immune evasion. Our findings not only unmask a novel regulatory mechanism of PD-L1 expression, but also suggest that PD-L1 3′-UTR disruption could serve as a genetic marker to identify cancers that actively evade anti-tumour immunity through PD-L1 overexpression.

Natural killer (NK) cells contribute to the first line of defense against viruses and to the control of tumor growth and metastasis spread. The discovery of HLA class I specific inhibitory receptors, primarily of killer Ig-like receptors (KIRs), and of activating receptors has been fundamental to unravel NK cell function and the molecular mechanisms of tumor cell killing. Stemmed from the seminal discoveries in early '90s, in which Alessandro Moretta was the major actor, an extraordinary amount of research on KIR specificity, genetics, polymorphism, and repertoire has followed. These basic notions on NK cells and their receptors have been successfully translated to clinical applications, primarily to the haploidentical hematopoietic stem cell transplantation to cure otherwise fatal leukemia in patients with no HLA compatible donors. The finding that NK cells may express the PD-1 inhibitory checkpoint, particularly in cancer patients, may allow understanding how anti-PD-1 therapy could function also in case of HLA class I tumors, usually susceptible to NK-mediated killing. This, together with the synergy of therapeutic anti-checkpoint monoclonal antibodies, including those directed against NKG2A or KIRs, emerging in recent or ongoing studies, opened new solid perspectives in cancer therapy.