Neoadjuvant cobimetinib and atezolizumab with or without vemurafenib for high-risk operable Stage III melanoma: the Phase II NeoACTIVATE trial.

Both targeted therapies and immunotherapies provide benefit in resected Stage III melanoma. We hypothesized that the combination of targeted and immunotherapy given prior to therapeutic lymph node dissection (TLND) would be tolerable and drive robust pathologic responses. In NeoACTIVATE (NCT03554083), a Phase II trial, patients with clinically evident resectable Stage III melanoma received either 12 weeks of neoadjuvant vemurafenib, cobimetinib, and atezolizumab (BRAF-mutated, Cohort A, n = 15), or cobimetinib and atezolizumab (BRAF-wild-type, Cohort B, n = 15) followed by TLND and 24 weeks of adjuvant atezolizumab. Here, we report outcomes from the neoadjuvant portion of the trial. Based on intent to treat analysis, pathologic response (≤50% viable tumor) and major pathologic response (complete or near-complete, ≤10% viable tumor) were observed in 86.7% and 66.7% of BRAF-mutated and 53.3% and 33.3% of BRAF-wild-type patients, respectively (primary outcome); these exceeded pre-specified benchmarks of 50% and 30% for major pathologic response. Grade 3 and higher toxicities, primarily dermatologic, occurred in 63% during neoadjuvant treatment (secondary outcome). No surgical delays nor progression to regional unresectability occurred (secondary outcome). Peripheral blood CD8 + TCM cell expansion associated with favorable pathologic responses (exploratory outcome).

A Novel PD-L1 Antibody Promotes Antitumor Function of Peripheral Cytotoxic Lymphocytes after Radical Nephrectomy in Patients with Renal Cell Carcinoma.

The intrinsic and acquired resistance to PD-1/PD-L1 immune checkpoint blockade is an important challenge for patients and clinicians because no reliable tool has been developed to predict individualized response to immunotherapy. In this study, we demonstrate the translational relevance of an ex vivo functional assay that measures the tumor cell killing ability of patient-derived CD8 T and NK cells (referred to as "cytotoxic lymphocytes," or CLs) isolated from the peripheral blood of patients with renal cell carcinoma. Patient-derived PBMCs were isolated before and after nephrectomy from patients with renal cell carcinoma. We compared the efficacy of U.S. Food and Drug Administration (FDA)-approved PD-1/PD-L1 inhibitors (pembrolizumab, nivolumab, atezolizumab) and a newly developed PD-L1 inhibitor (H1A Ab) in eliciting cytotoxic function. CL activity was improved at 3 mo after radical nephrectomy compared with baseline, and it was associated with higher circulating levels of tumor-reactive effector CD8 T cells (CD11ahighCX3CR1+GZMB+). Treatment of PBMCs with FDA-approved PD-1/PD-L1 inhibitors enhanced tumor cell killing activity of CLs, but a differential response was observed at the individual-patient level. H1A demonstrated superior efficacy in promoting CL activity compared with FDA-approved PD-1/PD-L1 inhibitors. PBMC immunophenotyping by mass cytometry revealed enrichment of effector CD8 T and NK cells in H1A-treated PBMCs and immunosuppressive regulatory T cells in atezolizumab-treated samples. Our study lays the ground for future investigation of the therapeutic value of H1A as a next-generation immune checkpoint inhibitor and the potential of measuring CTL activity in PBMCs as a tool to predict individual response to immune checkpoint inhibitors in patients with advanced renal cell carcinoma.

A Novel Humanized PD-1/PD-L1 Mouse Model Permits Direct Comparison of Antitumor Immunity Generated by Food and Drug Administration-Approved PD-1 and PD-L1 Inhibitors.

Seven different anti-PD-1 and PD-L1 mAbs are now widely used in the United States to treat a variety of cancer types, but no clinical trials have compared them directly. Furthermore, because many of these Abs do not cross-react between mouse and human proteins, no preclinical models exist in which to consider these types of questions. Thus, we produced humanized PD-1 and PD-L1 mice in which the extracellular domains of both mouse PD-1 and PD-L1 were replaced with the corresponding human sequences. Using this new model, we sought to compare the strength of the immune response generated by Food and Drug Administration-approved Abs. To do this, we performed an in vivo T cell priming assay in which anti-PD-1/L1 therapies were given at the time of T cell priming against surrogate tumor Ag (OVA), followed by subsequent B16-OVA tumor challenge. Surprisingly, both control and Ab-treated mice formed an equally robust OVA-specific T cell response at the time of priming. Despite this, anti-PD-1/L1-treated mice exhibited significantly better tumor rejection versus controls, with avelumab generating the best protection. To determine what could be mediating this, we identified the increased production of CX3CR1+PD-1+CD8+ cytotoxic T cells in the avelumab-treated mice, the same phenotype of effector T cells known to increase in clinical responders to PD-1/L1 therapy. Thus, our model permits the direct comparison of Food and Drug Administration-approved anti-PD-1/L1 mAbs and further correlates successful tumor rejection with the level of CX3CR1+PD-1+CD8 + T cells, making this model a critical tool for optimizing and better utilizing anti-PD-1/L1 therapeutics.

Pembrolizumab in Combination with Neoadjuvant Chemoradiotherapy for Patients with Resectable Adenocarcinoma of the Gastroesophageal Junction.

PURPOSE: This phase Ib/2 trial investigated pembrolizumab-containing trimodality therapy in patients with gastroesophageal junction (GEJ) adenocarcinoma. PATIENTS AND METHODS: Patients with GEJ adenocarcinoma (cT1-3NanyM0) received neoadjuvant pembrolizumab-containing chemoradiation (CROSS regimen) followed by surgical resection and adjuvant pembrolizumab. The primary endpoints were tolerability in the first 16 patients and pathologic complete response [pCR (ypT0N0)]. Secondary endpoints included progression-free survival (PFS) and overall survival (OS). An independent propensity-score-matched cohort (treated with CROSS without immunotherapy) was used for comparison. Exploratory analyses included immune biomarkers in the tumor microenvironment (TME) and plasma. RESULTS: We enrolled 31 eligible patients, of whom 29 received all expected doses of neoadjuvant pembrolizumab and 28 underwent R0 resection. Safety endpoints were met. The primary efficacy endpoint was not met [7/31 (22.6%) achieved pCR]. Patients with high [i.e., combined positive score (CPS) ≥ 10] baseline expression of programmed death (PD)-L1 in the TME had a significantly higher pCR rate than those with low expression [50.0% (4/8) vs. 13.6% (3/22); P = 0.046]. Patients with high PD-L1 expression also experienced longer PFS and OS than propensity-score-matched patients. Among trial patients with PD-L1 CPS < 10, unprespecified analysis explored whether extracellular vesicles (EV) could identify further responders: an elevated plasma level of PD-L1-expressing EVs was significantly associated with higher pCR. CONCLUSIONS: Adding pembrolizumab to trimodality therapy showed acceptable tolerability but did not meet the pre-specified pCR endpoint. Exploratory analyses suggested that high PD-L1 expression in the TME and/or on EVs may identify patients most likely to achieve tumor response.

NKG7 Is a T-cell-Intrinsic Therapeutic Target for Improving Antitumor Cytotoxicity and Cancer Immunotherapy.

Cytotoxic CD8+ T cells (CTL) are a crucial component of the immune system notable for their ability to eliminate rapidly proliferating malignant cells. However, the T-cell intrinsic factors required for human CTLs to accomplish highly efficient antitumor cytotoxicity are not well defined. By evaluating human CD8+ T cells from responders versus nonresponders to treatment with immune checkpoint inhibitors, we sought to identify key factors associated with effective CTL function. Single-cell RNA-sequencing analysis of peripheral CD8+ T cells from patients treated with anti-PD-1 therapy showed that cells from nonresponders exhibited decreased expression of the cytolytic granule-associated molecule natural killer cell granule protein-7 (NKG7). Functional assays revealed that reduced NKG7 expression altered cytolytic granule number, trafficking, and calcium release, resulting in decreased CD8+ T-cell-mediated killing of tumor cells. Transfection of T cells with NKG7 mRNA was sufficient to improve the tumor-cell killing ability of human T cells isolated from nonresponders and increase their response to anti-PD-1 or anti-PD-L1 therapy in vitro. NKG7 mRNA therapy also improved the antitumor activity of murine tumor antigen-specific CD8+ T cells in an in vivo model of adoptive cell therapy. Finally, we showed that the transcription factor ETS1 played a role in regulating NKG7 expression. Together, our results identify NKG7 as a necessary component for the cytotoxic function of CD8+ T cells and establish NKG7 as a T-cell-intrinsic therapeutic target for enhancing cancer immunotherapy.See related article by Li et al., p. 154.

Non-invasive immunoPET imaging of PD-L1 using anti-PD-L1-B11 in breast cancer and melanoma tumor model.

INTRODUCTION: Immunotherapy targeting PD-1/PD-L1 immune checkpoint inhibition (ICI) is efficacious in various solid and hematologic malignancies. However, the response rate to PD-1/PD-L1 therapy is only 15-35%. To obtain optimal clinical response to ICI therapies, a reliable assessment of tumor PD-L1 expression is needed to select appropriate patients, and a non-invasive imaging-based assessment of PD-L1 expression is critically needed. Although radiolabeled PET probes based on PD-L1 targeted therapeutic antibodies (e.g. atezolizumab) have shown encouraging results, there is concern that residual therapeutic antibody may compete for binding with the radiotracer thereby compromising imaging studies that follow treatment. METHODS AND RESULTS: In this study, we used novel anti-PD-L1-B11 clone antibody known to bind to a different epitope of PD-L1 than the therapeutic antibodies to avoid potential saturation effects. The anti-PD-L1-B11 clone was radiolabeled with zirconium-89 and evaluated to detect PD-L1 expression in various in vitro and in vivo cancer model systems in comparison with [89Zr]Zr-DFO-NCS-atezolizumab. In vitro binding parameters of anti-PD-L1-B11 were like those of atezolizumab. [89Zr]Zr-DFO-NCS-anti-PD-L1-B11 clone showed favorable properties to [89Zr]Zr-DFO-NCS-atezolizumab in an in vivo breast cancer tumor model system with higher uptake in PD-L1 expressing tumors. CONCLUSION: Our data demonstrates that [89Zr]Zr-DFO-NCS-anti-PD-L1-B11 exhibits excellent imaging properties for the assessment PD-L1 expression. The independent binding site of anti-PD-L1-B11 relative to therapeutic anti-PD-L1 antibodies may be advantageous for anti-PD-L1 therapy monitoring.

Therapeutic plasma exchange clears circulating soluble PD-L1 and PD-L1-positive extracellular vesicles.

BACKGROUND: Trans-acting programmed death-ligand 1 (PD-L1) derives from malignant cells in three known forms. High levels of secreted splice variant PD-L1 (sPD-L1), ADAM10/ADAM17-shed sPD-L1, and PD-L1-positive extracellular vesicles (evPD-L1) each predict poor prognosis and limited response to PD-(L)1 checkpoint inhibitors in cancer. To our knowledge, no clinical intervention has reduced any of these circulating forms of extracellular PD-L1. Here, we explore therapeutic plasma exchange (TPE) as a treatment to reduce circulating extracellular PD-L1. RESULTS: In patients with melanoma, sPD-L1 levels above 0.277 ng/mL predicted inferior overall survival. In patients undergoing TPE for non-malignant indications, each TPE session removed a mean 70.8% sPD-L1 and 73.1% evPD-L1 detectable in plasma. TPE also reduced total and ADAM10-positive extracellular vesicles. CONCLUSION: Here, we report the first known clinical intervention to remove either sPD-L1 or evPD-L1 from plasma in vivo. TPE reduces plasma sPD-L1 and evPD-L1 in vivo and may have a role in treatment with immunotherapy. TPE may also prove useful in patients with other extracellular vesicle-related conditions.

Circulating levels of PD-L1 and Galectin-9 are associated with patient survival in surgically treated Hepatocellular Carcinoma independent of their intra-tumoral expression levels.

Tumor expression of immune co-inhibitory ligands, such as PD-L1 and Galectin-9, have potential prognostic value in Hepatocellular Carcinoma (HCC). Circulating levels of these molecules, however, have hardly been studied. This study aims to assess the prognostic significance of circulating PD-L1 and circulating Galectin-9 in patients with resected HCC, and to compare their prognostic significance to the intra-tumoral expression of these same molecules. Archived tissues and stored peripheral blood samples from 81 patients who underwent HCC resection or liver transplantation, with curative intent, were used. Immunohistochemistry was performed to determine intra-tumoral expression of PD-L1 and Galectin-9, while ELISA was used to quantify their respective circulating levels. High circulating PD-L1 (HR 0.12, 95%CI 0.16-0.86, p = 0.011) and high circulating Galectin-9 (HR 0.11, 95%CI 0.15-0.85, p = 0.010) levels were both associated with improved HCC-specific survival. Surprisingly, there was no correlation between circulating levels of PD-L1 and Galectin-9 and their intra-tumoral expression levels. In fact, circulating levels of PD-L1 and Galectin-9 were predictive of HCC-specific survival independently of intra-tumoral levels and baseline clinicopathologic characteristics. Combined analysis of circulating levels and intra-tumoral expression of PD-L1 (HR 0.33, 95%CI 0.16-0.68, p = 0.002) and Galectin-9 (HR 0.27, 95%CI 0.13-0.57, p = 0.001) resulted in more confident prediction of survival. In conclusion, circulating PD-L1 and Galectin-9 levels prognostically differentiate resected HCC patients, independently of their intra-tumoral expression. Combining circulating and intra-tumoral expression levels of PD-L1 or Galectin-9 further improves the prognostic values of these immune biomarkers.

Corrigendum to "Targeting B7-H1 (PD-L1) sensitizes cancer cells to chemotherapy" [Heliyon 4 (12) (December 2018) e01039].

[This corrects the article DOI: 10.1016/j.heliyon.2018.e01039.].

Chronic laryngitis caused by Mycobacterium Kansasii in a traveler.

Chronic laryngitis commonly presents with dysphonia, and infectious causes include tuberculosis and endemic mycoses. We present a 58-year-old female with laryngitis for 5 years, fevers, chills, fatigue, malaise, myalgias, anterior neck pain, and night sweats after multicontinent exposure. Bronchoscopy cultures were negative. Bilateral microflap excision of vocal fold lesions demonstrated thickened epithelium and a deep vocal fold mass. Biopsy showed necrotizing granulomatous inflammation with acid-fast bacilli. Mycobacterium kansasii was identified. Treatment led to improvement in dysphonia, systemic symptoms, and vocal fold irritation. To our knowledge, this is the first case of isolated nontuberculous mycobacterial vocal fold infection. Laryngoscope, 129:2534-2536, 2019.

CX3CR1 identifies PD-1 therapy-responsive CD8+ T cells that withstand chemotherapy during cancer chemoimmunotherapy.

Although immune checkpoint inhibitors have resulted in durable clinical benefits in a subset of patients with advanced cancer, some patients who did not respond to initial anti-PD-1 therapy have been found to benefit from the addition of salvage chemotherapy. However, the mechanism responsible for the successful chemoimmunotherapy is not completely understood. Here we show that a subset of circulating CD8+ T cells expressing the chemokine receptor CX3CR1 are able to withstand the toxicity of chemotherapy and are increased in patients with metastatic melanoma who responded to chemoimmunotherapy (paclitaxel and carboplatin plus PD-1 blockade). These CX3CR1+CD8+ T cells have effector memory phenotypes and the ability to efflux chemotherapy drugs via the ABCB1 transporter. In line with clinical observation, our preclinical models identified an optimal sequencing of chemoimmunotherapy that resulted in an increase of CX3CR1+CD8+ T cells. Taken together, we found a subset of PD-1 therapy-responsive CD8+ T cells that were capable of withstanding chemotherapy and executing tumor rejection with their unique abilities of drug efflux (ABCB1), cytolytic activity (granzyme B and perforin), and migration to and retention (CX3CR1 and CD11a) at tumor sites. Future strategies to monitor and increase the frequency of CX3CR1+CD8+ T cells may help to design effective chemoimmunotherapy to overcome cancer resistance to immune checkpoint blockade therapy.

Bim is an independent prognostic marker in intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is the second most common primary liver malignant tumor and has a poor prognosis. The prognostic factors associated with outcome remain poorly defined. In this study, we investigated the role of an important cell apoptosis initiator, Bcl-2 interacting mediator of cell death (Bim), by evaluating its expression and association with other clinicopathological features in ICCs. We analyzed 56 cases of ICC with clinical follow-up. The expression of Bim in ICC cells and other cellular components was evaluated by immunohistochemistry. Bim expression was considered up-regulated if Bim was detected in 10% or more of tumor cells. Of the 56 ICC samples, 19 (34%) had high Bim expression level, 15 (27%) were completely negative, and 22 (39%) were classified as low Bim expression (<10% positivity). Patients who had tumors with high Bim level had significantly longer overall survival than did those with low or no staining (median survival, 7.6 versus 2.6 years; hazard ratio, 0.40; P = .006). High Bim expression was also correlated with low Ki-67 index, and more importantly, none of the tumors with high Bim expression had lymph node metastases at the time of surgery. Our study demonstrates that Bim is an important and independent prognostic factor in ICC. Tumors with high Bim expression are associated with better prognosis through inhibiting tumor cell proliferation and metastatic ability. The development of new agents directly or indirectly targeting Bim may provide promising anticancer treatments.

PD-L1 on host cells is essential for PD-L1 blockade-mediated tumor regression.

Programmed death-ligand 1 (PD-L1) expression on tumor cells is essential for T cell impairment, and PD-L1 blockade therapy has shown unprecedented durable responses in several clinical studies. Although higher expression of PD-L1 on tumor cells is associated with a better immune response after Ab blockade, some PD-L1-negative patients also respond to this therapy. In the current study, we explored whether PD-L1 on tumor or host cells was essential for anti-PD-L1-mediated therapy in 2 different murine tumor models. Using real-time imaging in whole tumor tissues, we found that anti-PD-L1 Ab accumulates in tumor tissues, regardless of the status of PD-L1 expression on tumor cells. We further observed that, while PD-L1 on tumor cells was largely dispensable for the response to checkpoint blockade, PD-L1 in host myeloid cells was essential for this response. Additionally, PD-L1 signaling in defined antigen-presenting cells (APCs) negatively regulated and inhibited T cell activation. PD-L1 blockade inside tumors was not sufficient to mediate regression, as limiting T cell trafficking reduced the efficacy of the blockade. Together, these findings demonstrate that PD-L1 expressed in APCs, rather than on tumor cells, plays an essential role in checkpoint blockade therapy, providing an insight into the mechanisms of this therapy.

Targeting B7-H1 (PD-L1) sensitizes cancer cells to chemotherapy.

Development of resistance to chemotherapy is a major obstacle in extending the survival of patients with cancer. Although originally defined as an immune checkpoint molecule, B7-H1 (also named as PD-L1 or CD274) was found to play a role in cancer chemoresistance; however, the underlying mechanism of action of B7-H1 in regulation of chemotherapy sensitivity remains unclear in cancer cells. Here we show that development of chemoresistance depends on an increased activation of ERK in cancer cells overexpressing B7-H1. Conversely, B7-H1 knockout (KO) by CRISPR/Cas9 renders human cancer cells susceptible to chemotherapy in a cell-context dependent manner through a reduced activation of p38 MAPK. B7-H1 was found to associate with the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) and this association promoted or maintained the activation of ERK or p38 MAPK in cancer cells. Importantly, we found that targeting B7-H1 by anti-B7-H1 monoclonal antibody (H1A) increased the sensitivity of human triple negative breast cancer cells to cisplatin therapy in vivo. Our results suggest that targeting B7-H1 by an antibody capable of disrupting B7-H1 signals may be a new approach to sensitize cancer cells to chemotherapy.

Immune checkpoint molecules soluble program death ligand 1 and galectin-9 are increased in pregnancy.

PROBLEM: Pregnancy requires balance between tolerance to the haploidentical fetus and the mother's ability to mount immune responses. There are parallels to this phenomenon that occur in metastatic cancer. We assessed soluble program death ligand-1 soluble PD-L1 (sPD-L1) and galectin-9 in the blood of pregnant women during gestation as these molecules are highly involved in immune suppression during cancer. METHOD OF STUDY: Maternal blood was collected from 30 primigravida women at monthly intervals during pregnancy, delivery and 6-week post-partum. Blood was analyzed for sPD-L1 and galectin-9 concentrations by ELISA. Term placentas were collected in formalin and IHC was completed for PD-L1 and galectin-9 expression. RESULTS: Maternal blood levels of sPD-L1 (0.438 ng/mL) and galectin-9 (1976 pg/mL) were elevated early in normal pregnancies compared to non-pregnant controls (0.242 ng/mL and 773 pg/mL, respectively). sPD-L1 increased throughout gestation, whereas galectin-9 remained elevated until parturition; both proteins returned to control levels post-partum. Women carrying male fetuses had significantly higher galectin-9 levels, but not sPD-L1, than those carrying females (2263 pg/mL vs 1874 pg/mL; P = .0005). Trophoblast cells of the term placenta coexpress galectin-9 and PD-L1. CONCLUSION: Immune-regulatory molecules galectin-9 and sPD-L1 increased during pregnancy and may play a role in immune tolerance that is critical for the fetus.

B7-H1 Influences the Accumulation of Virus-Specific Tissue Resident Memory T Cells in the Central Nervous System.

Therapies that target the PD-1/B7-H1 axis have revolutionized cancer treatment, yet precise knowledge of how this pathway provides benefit continues to evolve. Here, we report a novel role for the immune checkpoint ligand B7-H1 in the accumulation of tissue-resident memory CD8+ T-cells (TRM). After intracranial infection, Theiler's murine encephalomyelitis virus (TMEV) generates TRM that are maintained in the central nervous system (CNS) tissues of B7-H1WT animals. Although no differences in acute T-cell responses between B7-H1WT and B7-H1KO are observed, at long-term periods post-infection the maintenance of CD8+ TRM is diminished in B7-H1KO animals. This is accompanied by redistribution of the resident CD8+ population from primarily CD103+ TRM to a diminished population of TRM and a preponderance of non-specified PD-1+ CD103- CD8+ T-cells. T-cell transfer studies demonstrate that host B7-H1 is necessary for maintaining TRM and limiting accumulation of PD-1+ CD103- CD8+ T-cells. The lack of host B7-H1 results in compromised control of a heterologous virus re-challenge demonstrating a functional defect in TRM mediated virus control. This study reveals a new role for B7-H1 in TRM and pro-inflammatory PD-1+ CD103- CD8+ T-cell accumulation in the CNS and gives insight for using B7-H1/PD-1 blockade in modulating long-term T-cell protection.

B7-H1 antibodies lose antitumor activity due to activation of p38 MAPK that leads to apoptosis of tumor-reactive CD8+ T cells.

B7-H1 (aka PD-L1) blocking antibodies have been used in treatment of human cancers through blocking B7-H1 expressed by tumor cells; however, their impact on B7-H1 expressing tumor-reactive CD8+ T cells is still unknown. Here, we report that tumor-reactive CD8+ T cells expressing B7-H1 are functional effector cells. In contrast to normal B7-H1 blocking antibody, B7-H1 antibodies capable of activating p38 MAPK lose their antitumor activity by deleting B7-H1+ tumor-reactive CD8+ T cells via p38 MAPK pathway. B7-H1 deficiency or engagement with certain antibody results in more activation of p38 MAPK that leads to T cell apoptosis. DNA-PKcs is a new intracellular partner of B7-H1 in the cytoplasm of activated CD8+ T cells. B7-H1 suppresses p38 MAPK activation by sequestering DNA-PKcs in order to preserve T cell survival. Our findings provide a new mechanism of action of B7-H1 in T cells and have clinical implications in cancer immunotherapy when anti-B7-H1 (PD-L1) antibody is applied.

CpG-induced antitumor immunity requires IL-12 in expansion of effector cells and down-regulation of PD-1.

CpG oligodeoxynucleotides, as a ligand of toll-like receptor (TLR)-9, have demonstrated promising antitumor effects in some clinical trials; however, its toxicity and low efficacy as a systemic therapy has limited its therapeutic applications. In order to improve its therapeutic efficacy, we investigated the mechanisms of CpG-induced antitumor immunity in the context of CD8+ T cell responses. We show that IL-12 is required for the expansion of IFN-γ producing tumor-reactive CD8+ T cells capable of rejecting tumors. In addition, CpGs reduced PD-1 expression by effector CD8+ T cells via the IL-12 pathway. The combination of CpG and PD-1 blockade show a synergistic effect in generation of systemic antitumor immunity. Our studies define a critical role of IL-12 in CpG-induced antitumor immunity and provide a rationale for combined therapy with TLR agonists and immune checkpoint blockade in cancer treatment.

T cell Bim levels reflect responses to anti-PD-1 cancer therapy.

Immune checkpoint therapy with PD-1 blockade has emerged as an effective therapy for many advanced cancers; however, only a small fraction of patients achieve durable responses. To date, there is no validated blood-based means of predicting the response to PD-1 blockade. We report that Bim is a downstream signaling molecule of the PD-1 pathway, and its detection in T cells is significantly associated with expression of PD-1 and effector T cell markers. High levels of Bim in circulating tumor-reactive (PD-1+CD11ahiCD8+) T cells were prognostic of poor survival in patients with metastatic melanoma who did not receive anti-PD-1 therapy and were also predictive of clinical benefit in patients with metastatic melanoma who were treated with anti-PD-1 therapy. Moreover, this circulating tumor-reactive T cell population significantly decreased after successful anti-PD-1 therapy. Our study supports a crucial role of Bim in both T cell activation and apoptosis as regulated by PD-1 and PD-L1 interactions in effector CD8+ T cells. Measurement of Bim levels in circulating T cells of patients with cancer may provide a less invasive strategy to predict and monitor responses to anti-PD-1 therapy, although future prospective analyses are needed to validate its utility.

Lawsonella clevelandensis gen. nov., sp. nov., a new member of the suborder Corynebacterineae isolated from human abscesses.

Gram-stain-positive, partially acid-fast, non-spore-forming, anaerobic, catalase-positive, pleomorphic bacteria were isolated from human abscesses. Strains X1036T, X1698 and NML 120705, were recovered from a spinal abscess, a peritoneal abscess and a breast abscess respectively. A phylogenetic analysis of the 16S rRNA gene sequences showed that the strains shared 100 % similarity, and the nearest phylogenetic neighbour was Dietzia timorensis DSM 45568T (95%). Chemotaxonomic characteristics of the strains were consistent with those described for members of the suborder Corynebacterineae. Mycolic acids were detected using HPLC and one-dimensional TLC; whole-cell hydrolysates yielded meso-diaminopimelic acid with arabinose and galactose as the predominant sugars; the muramic acid acyl type was acetylated; the major menaquinone was MK-9 (96.3%); polar lipids detected were phosphatidylglycerol, phosphatidylinositol and an unknown glycophospholipid. Cellular fatty acids were hexadecanoic acid (C16 : 0), octadecenoic acid (C18 : 1ω9c) and decanoic acid (C10 : 0). Tuberculostearic acid was not detected. Based on the results of this polyphasic study, we conclude that these strains represent a novel genus and species within the suborder Corynebacterineae for which we propose the name Lawsonella clevelandensis gen. nov., sp. nov., with the type strain X1036T (=DSM 45743T=CCUG 66657T).