Integrative multi-omics profiling in human decedents receiving pig heart xenografts

In a previous study, heart xenografts from 10-gene-edited pigs transplanted into two human decedents did not show evidence of acute-onset cellular- or antibody-mediated rejection. Here, to better understand the detailed molecular landscape following xenotransplantation, we carried out bulk and single-cell transcriptomics, lipidomics, proteomics and metabolomics on blood samples obtained from the transplanted decedents every 6 h, as well as histological and transcriptomic tissue profiling. We observed substantial early immune responses in peripheral blood mononuclear cells and xenograft tissue obtained from decedent 1 (male), associated with downstream T cell and natural killer cell activity. Longitudinal analyses indicated the presence of ischemia reperfusion injury, exacerbated by inadequate immunosuppression of T cells, consistent with previous findings of perioperative cardiac xenograft dysfunction in pig-to-nonhuman primate studies. Moreover, at 42 h after transplantation, substantial alterations in cellular metabolism and liver-damage pathways occurred, correlating with profound organ-wide physiological dysfunction. By contrast, relatively minor changes in RNA, protein, lipid and metabolism profiles were observed in decedent 2 (female) as compared to decedent 1. Overall, these multi-omics analyses delineate distinct responses to cardiac xenotransplantation in the two human decedents and reveal new insights into early molecular and immune responses after xenotransplantation. These findings may aid in the development of targeted therapeutic approaches to limit ischemia reperfusion injury-related phenotypes and improve outcomes.

mRNA COVID-19 vaccine elicits potent adaptive immune response without the acute inflammation of SARS-CoV-2 infection

SARS-CoV-2 infection and vaccination elicit potent immune responses. Our study presents a comprehensive multimodal single-cell analysis of blood from COVID-19 patients and healthy volunteers receiving the SARS-CoV-2 vaccine and booster. We profiled immune responses via transcriptional analysis and lymphocyte repertoire reconstruction. COVID-19 patients displayed an enhanced interferon signature and cytotoxic gene upregulation, absent in vaccine recipients. B and T cell repertoire analysis revealed clonal expansion among effector cells in COVID-19 patients and memory cells in vaccine recipients. Furthermore, while clonal αβ T cell responses were observed in both COVID-19 patients and vaccine recipients, expansion of clonal γδ T cells was found only in infected individuals. Our dataset enables side-by-side comparison of immune responses to infection versus vaccination, including clonal B and T cell responses. Our comparative analysis shows that vaccination induces a robust, durable clonal B and T cell responses, without the severe inflammation associated with infection.

Immune response, phenotyping and molecular graft surveillance in kidney transplant recipients following severe acute respiratory syndrome coronavirus 2 vaccination

BACKGROUND

Understanding immunogenicity and alloimmune risk following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in kidney transplant recipients is imperative to understanding the correlates of protection and to inform clinical guidelines.

METHODS

We studied 50 kidney transplant recipients following SARS-CoV-2 vaccination and quantified their anti-spike protein antibody, donor-derived cell-free DNA (dd-cfDNA), gene expression profiling (GEP), and alloantibody formation.

RESULTS

Participants were stratified using nucleocapsid testing as either SARS-CoV-2-naïve or experienced prior to vaccination. One of 34 (3%) SARS-CoV-2 naïve participants developed anti-spike protein antibodies. In contrast, the odds ratio for the association of a prior history of SARS-CoV-2 infection with vaccine response was 18.3 (95% confidence interval 3.2, 105.0, p < 0.01). Pre- and post-vaccination levels did not change for median dd-cfDNA (0.23% vs. 0.21% respectively, p = 0.13), GEP scores (9.85 vs. 10.4 respectively, p = 0.45), calculated panel reactive antibody, de-novo donor specific antibody status, or estimated glomerular filtration rate.

CONCLUSIONS

SARS-CoV-2 vaccines do not appear to trigger alloimmunity in kidney transplant recipients. The degree of vaccine immunogenicity was associated most strongly with a prior history of SARS-CoV-2 infection.

Multimodal single-cell datasets characterize antigen-specific CD8+ T cells across SARS-CoV-2 vaccination and infection

The immune response to SARS-CoV-2 antigen after infection or vaccination is defined by the durable production of antibodies and T cells. Population-based monitoring typically focuses on antibody titer, but there is a need for improved characterization and quantification of T cell responses. Here, we used multimodal sequencing technologies to perform a longitudinal analysis of circulating human leukocytes collected before and after immunization with the mRNA vaccine BNT162b2. Our data indicated distinct subpopulations of CD8+ T cells, which reliably appeared 28 days after prime vaccination. Using a suite of cross-modality integration tools, we defined their transcriptome, accessible chromatin landscape and immunophenotype, and we identified unique biomarkers within each modality. We further showed that this vaccine-induced population was SARS-CoV-2 antigen-specific and capable of rapid clonal expansion. Moreover, we identified these CD8+ T cell populations in scRNA-seq datasets from COVID-19 patients and found that their relative frequency and differentiation outcomes were predictive of subsequent clinical outcomes.

mRNA COVID-19 vaccine elicits potent adaptive immune response without the persistent inflammation seen in SARS-CoV-2 infection

SARS-CoV-2 infection and vaccination elicit potent immune responses. Our study presents a comprehensive multimodal single-cell dataset of peripheral blood of patients with acute COVID-19 and of healthy volunteers before and after receiving the SARS-CoV-2 mRNA vaccine and booster. We compared host immune responses to the virus and vaccine using transcriptional profiling, coupled with B/T cell receptor repertoire reconstruction. COVID-19 patients displayed an enhanced interferon signature and cytotoxic gene upregulation, absent in vaccine recipients. These findings were validated in an independent dataset. Analysis of B and T cell repertoires revealed that, while the majority of clonal lymphocytes in COVID-19 patients were effector cells, clonal expansion was more evident among circulating memory cells in vaccine recipients. Furthermore, while clonal αβ T cell responses were observed in both COVID-19 patients and vaccine recipients, dramatic expansion of clonal γδT cells was found only in infected individuals. Our dataset enables comparative analyses of immune responses to infection versus vaccination, including clonal B and T cell responses. Integrating our data with publicly available datasets allowed us to validate our findings in larger cohorts. To our knowledge, this is the first dataset to include comprehensive profiling of longitudinal samples from healthy volunteers pre/post SARS-CoV-2 vaccine and booster.

High-throughput interrogation of immune responses using the Human Immune Profiling Pipeline

The current abundance of immunotherapy clinical trials presents an opportunity to learn about the underlying mechanisms and pharmacodynamic effects of novel drugs on the human immune system. Here, we present a protocol to study how these immune responses impact clinical outcomes using large-scale high-throughput immune profiling of clinical cohorts. We describe the Human Immune Profiling Pipeline, which comprises an end-to-end solution from flow cytometry results to computational approaches and unsupervised patient clustering based on lymphocyte landscape. For complete details on the use and execution of this protocol, please refer to Lyudovyk et al. (2022).1.

Human T follicular helper clones seed the germinal center-resident regulatory pool

The mechanisms by which FOXP3+ T follicular regulatory (Tfr) cells simultaneously steer antibody formation toward microbe or vaccine recognition and away from self-reactivity remain incompletely understood. To explore underappreciated heterogeneity in human Tfr cell development, function, and localization, we used paired TCRVA/TCRVB sequencing to distinguish tonsillar Tfr cells that are clonally related to natural regulatory T cells (nTfr) from those likely induced from T follicular helper (Tfh) cells (iTfr). The proteins iTfr and nTfr cells differentially expressed were used to pinpoint their in situ locations via multiplex microscopy and establish their divergent functional roles. In silico analyses and in vitro tonsil organoid tracking models corroborated the existence of separate Treg-to-nTfr and Tfh-to-iTfr developmental trajectories. Our results identify human iTfr cells as a distinct CD38+, germinal center-resident, Tfh-descended subset that gains suppressive function while retaining the capacity to help B cells, whereas CD38- nTfr cells are elite suppressors primarily localized in follicular mantles. Interventions differentially targeting specific Tfr cell subsets may provide therapeutic opportunities to boost immunity or more precisely treat autoimmune diseases.

Multimodal characterization of antigen-specific CD8 + T cells across SARS-CoV-2 vaccination and infection

The human immune response to SARS-CoV-2 antigen after infection or vaccination is defined by the durable production of antibodies and T cells. Population-based monitoring typically focuses on antibody titer, but there is a need for improved characterization and quantification of T cell responses. Here, we utilize multimodal sequencing technologies to perform a longitudinal analysis of circulating human leukocytes collected before and after BNT162b2 immunization. Our data reveal distinct subpopulations of CD8 + T cells which reliably appear 28 days after prime vaccination (7 days post boost). Using a suite of cross-modality integration tools, we define their transcriptome, accessible chromatin landscape, and immunophenotype, and identify unique biomarkers within each modality. By leveraging DNA-oligo-tagged peptide-MHC multimers and T cell receptor sequencing, we demonstrate that this vaccine-induced population is SARS-CoV-2 antigen-specific and capable of rapid clonal expansion. Moreover, we also identify these CD8 + populations in scRNA-seq datasets from COVID-19 patients and find that their relative frequency and differentiation outcomes are predictive of subsequent clinical outcomes. Our work contributes to our understanding of T cell immunity, and highlights the potential for integrative and multimodal analysis to characterize rare cell populations.

Abstract 3579: T cell intrinsic DNA damage and repair response as a novel marker associated with clinical response to PD-1 blockade

Despite the high tumor mutational burden (TMB), immune check point blockade (ICB) still fails in about half of microsatellite instability-high (MSI-H) cancer patients, suggesting underlying immune dysregulation. Immune profiling of peripheral blood from chemotherapy-resistant MSI-H uterine cancer patients treated with nivolumab identified a rapid proliferative CD8 T cell response 2-4 weeks post PD-1 blockade (N = 32). This immunological response, however, did not correlate with clinical response, suggesting additional parameters may be relevant. We focused on DNA damage and repair (DDR) in T cells as potential novel parameters. DDR has been extensively studied in the context of inducing cell death in highly-proliferating tumor cells. However, despite induction of rapid proliferation of T cells upon ICB, whether T cell-intrinsic DDR impacts T cell function, and how the coordination of DDR affects immunological and clinical response to ICBs have been largely unexplored. We hypothesized that the T celI-intrinsic DDR responses to proliferative and genotoxic stress might contribute to the disparity between immunological and clinical response. To test the hypothesis, we developed a novel high-dimensional cytometry platform. This DDR-Immune platform enables simultaneous analysis of T cell differentiation state with changes in major DDR pathways at single-cell resolution. The DDR-Immune platform revealed consistent T cell subset specific patterns of DDR, as well as specific DDR pathways induced by different types of DNA damage, such as γ-irradiation (IR), UV irradiation (UV) or proliferative stress (i.e. anti-CD3/CD28 stimulation). For example, terminally differentiated effector T cells accumulated higher DNA damage and cell death. In contrast, stem cell memory (TSCM) and regulatory T cells (Treg) displayed high DDR with less cell death, suggesting that effective cell-intrinsic DDR against genotoxic stress in T cells confers a survival advantage. We applied the platform to MSI-H uterine cancer cohort to test if T cell-intrinsic DDR distinguish the clinical response. Indeed, we found that in clinical responders but not clinical non-responders, Ki67+ CD8 T cells responding to PD-1 blockade exhibited rapid induction of DDR represented as a spike increase of phosphorylated-ATM (pATM). This likely indicates the T cell ‘fitness’ response to proliferative stress induced by PD-1 blockade. Furthermore, patients with higher induction of pATM in responding CD8 T cells at the peak of the immunological response to PD-1 blockade had longer progression-free survival (PFS). Collectively, the new platform reveals previously unrecognized roles for T cell-intrinsic DDR as a novel determinant of immune responsiveness and clinical outcome to ICB and has potential application to other cancer therapies including chemotherapy and radiotherapy.

Citation Format: Yuki Muroyama, Sasikanth Manne, Derek A. Oldridge, Nils Wellhausen, Allison R. Greenplate, Lakshmi Chilukuri, Divij Mathew, Caiyue Xu, Ramin S. Herati, Alexander C. Huang, Dmitriy Zamarin, Claire F. Friedman, E. John Wherry. T cell intrinsic DNA damage and repair response as a novel marker associated with clinical response to PD-1 blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3579.

Increased resistance of SARS-CoV-2 Omicron variant to neutralization by vaccine-elicited and therapeutic antibodies

BACKGROUND

SARS-CoV-2 vaccines currently authorized for emergency use have been highly successful in preventing infection and lessening disease severity. The vaccines maintain effectiveness against earlier SARS-CoV-2 Variants of Concern but the heavily mutated, highly transmissible Omicron variant presents an obstacle both to vaccine protection and monoclonal antibody therapies.

METHODS

Pseudotyped lentiviruses were incubated with serum from vaccinated and boosted donors or therapeutic monoclonal antibody and then applied to target cells. After 2 days, luciferase activity was measured in a microplate luminometer. Resistance mutations of the Omicron spike were identified using point-mutated spike protein pseudotypes and mapped onto the three-dimensional spike protein structure.

FINDINGS

Virus with the Omicron spike protein was 26-fold resistant to neutralization by recovered donor sera and 26-34-fold resistance to Pfizer BNT162b2 and Moderna vaccine-elicited antibodies following two immunizations. A booster immunization increased neutralizing titres against Omicron. Neutralizing titres against Omicron were increased in the sera with a history of prior SARS-CoV-2 infection. Analysis of the therapeutic monoclonal antibodies showed that the Regeneron and Eli Lilly monoclonal antibodies were ineffective against the Omicron pseudotype while Sotrovimab and Evusheld were partially effective.

INTERPRETATION

The results highlight the benefit of a booster immunization to protect against the Omicron variant and demonstrate the challenge to monoclonal antibody therapy. The decrease in neutralizing titres against Omicron suggest that much of the vaccine efficacy may rely on T cells.

FUNDING

The work was funded by grants from the NIH to N.R.L. (DA046100, AI122390 and AI120898) and 55 to M.J.M. (UM1AI148574).

Neutralization of SARS-CoV-2 Variants by mRNA and Adenoviral Vector Vaccine-Elicited Antibodies

The increasing prevalence of SARS-CoV-2 variants has raised concerns regarding possible decreases in vaccine effectiveness. Here, neutralizing antibody titers elicited by mRNA-based and adenoviral vector-based vaccines against variant pseudotyped viruses were measured. BNT162b2 and mRNA-1273-elicited antibodies showed modest neutralization resistance against Beta, Delta, Delta plus and Lambda variants whereas Ad26.COV2.S-elicited antibodies from a significant fraction of vaccinated individuals had less neutralizing titer (IC₅₀ <50). The data underscore the importance of surveillance for breakthrough infections that result in severe COVID-19 and suggest a potential benefit by second immunization following Ad26.COV2.S to increase protection from current and future variants.

Evaluation of Immune Response and Disease Status in Systemic Lupus Erythematosus Patients Following SARS-CoV-2 Vaccination

OBJECTIVE

To evaluate seroreactivity and disease flares after COVID-19 vaccination in a multiethnic/multiracial cohort of patients with systemic lupus erythematosus (SLE).

METHODS

Ninety SLE patients and 20 healthy controls receiving a complete COVID-19 vaccine regimen were included. IgG seroreactivity to the SARS-CoV-2 spike receptor-binding domain (RBD) and SARS-CoV-2 microneutralization were used to evaluate B cell responses; interferon-γ (IFNγ) production was measured by enzyme-linked immunospot (ELISpot) assay in order to assess T cell responses. Disease activity was measured by the hybrid SLE Disease Activity Index (SLEDAI), and flares were identified according to the Safety of Estrogens in Lupus Erythematosus National Assessment-SLEDAI flare index.

RESULTS

Overall, fully vaccinated SLE patients produced significantly lower IgG antibodies against SARS-CoV-2 spike RBD compared to fully vaccinated controls. Twenty-six SLE patients (28.8%) generated an IgG response below that of the lowest control (<100 units/ml). In logistic regression analyses, the use of any immunosuppressant or prednisone and a normal anti-double-stranded DNA antibody level prior to vaccination were associated with decreased vaccine responses. IgG seroreactivity to the SARS-CoV-2 spike RBD strongly correlated with the SARS-CoV-2 microneutralization titers and correlated with antigen-specific IFNγ production determined by ELISpot. In a subset of patients with poor antibody responses, IFNγ production was similarly diminished. Pre- and postvaccination SLEDAI scores were similar in both groups. Postvaccination flares occurred in 11.4% of patients; 1.3% of these were severe.

CONCLUSION

In a multiethnic/multiracial study of SLE patients, 29% had a low response to the COVID-19 vaccine which was associated with receiving immunosuppressive therapy. Reassuringly, severe disease flares were rare. While minimal protective levels remain unknown, these data suggest that protocol development is needed to assess the efficacy of booster vaccination.

High-titer neutralization of Mu and C.1.2 SARS-CoV-2 variants by vaccine-elicited antibodies of previously infected individuals

Recently identified severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants Mu and C.1.2 have spike proteins with mutations that may confer resistance to natural and vaccine-elicited antibodies. Analysis of neutralizing antibody titers in the sera of vaccinated individuals without previous history of infection and from convalescent individuals show partial resistance of the viruses. In contrast, sera from individuals with a previous history of SARS-CoV-2 infection who were subsequently vaccinated neutralize variants with titers 4- to 11-fold higher, providing a rationale for vaccination of individuals with previous infection. The heavily mutated C.1.2 spike is the most antibody neutralization-resistant spike to date; however, the avidity of C.1.2 spike protein for angiotensin-converting enzyme 2 (ACE2) is low. This finding suggests that the virus evolved to escape the humoral response but has a decrease in fitness, suggesting that it may cause milder disease or be less transmissible. It may be difficult for the spike protein to evolve to escape neutralizing antibodies while maintaining high affinity for ACE2.

Rapid induction of antigen-specific CD4+ T cells is associated with coordinated humoral and cellular immunity to SARS-CoV-2 mRNA vaccination

SARS-CoV-2 mRNA vaccines have shown remarkable clinical efficacy, but questions remain about the nature and kinetics of T cell priming. We performed longitudinal antigen-specific T cell analyses on healthy SARS-CoV-2-naive and recovered individuals prior to and following mRNA prime and boost vaccination. Vaccination induced rapid antigen-specific CD4+ T cell responses in naive subjects after the first dose, whereas CD8+ T cell responses developed gradually and were variable in magnitude. Vaccine-induced Th1 and Tfh cell responses following the first dose correlated with post-boost CD8+ T cells and neutralizing antibodies, respectively. Integrated analysis revealed coordinated immune responses with distinct trajectories in SARS-CoV-2-naive and recovered individuals. Last, whereas booster vaccination improved T cell responses in SARS-CoV-2-naive subjects, the second dose had little effect in SARS-CoV-2-recovered individuals. These findings highlight the role of rapidly primed CD4+ T cells in coordinating responses to the second vaccine dose in SARS-CoV-2-naive individuals.

Convalescent-Phase Sera and Vaccine-Elicited Antibodies Largely Maintain Neutralizing Titer against Global SARS-CoV-2 Variant Spikes

The increasing prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with spike protein mutations raises concerns that antibodies elicited by natural infection or vaccination and therapeutic monoclonal antibodies will become less effective. We show that convalescent-phase sera neutralize pseudotyped viruses with the B.1.1.7, B.1.351, B.1.1.248, COH.20G/677H, 20A.EU2, and mink cluster 5 spike proteins with only a minor loss in titer. Similarly, antibodies elicited by Pfizer BNT162b2 vaccination neutralized B.1.351 and B.1.1.248 with only a 3-fold decrease in titer, an effect attributable to E484K. Analysis of the Regeneron monoclonal antibodies REGN10933 and REGN10987 showed that REGN10933 has lost neutralizing activity against the B.1.351 and B.1.1.248 pseudotyped viruses, and the cocktail is 9- to 15-fold decreased in titer. These findings suggest that antibodies elicited by natural infection and by the Pfizer vaccine will maintain protection against the B.1.1.7, B.1.351, and B.1.1.248 variants but that monoclonal antibody therapy may be less effective for patients infected with B.1.351 or B.1.1.248 SARS-CoV-2. IMPORTANCE The rapid evolution of SARS-CoV-2 variants has raised concerns with regard to their potential to escape from vaccine-elicited antibodies and anti-spike protein monoclonal antibodies. We report here on an analysis of sera from recovered patients and vaccinated individuals and on neutralization by Regeneron therapeutic monoclonal antibodies. Overall, the variants were neutralized nearly as well as the wild-type pseudotyped virus. The B.1.351 variant was somewhat resistant to vaccine-elicited antibodies but was still readily neutralized. One of the two Regeneron therapeutic monoclonal antibodies seems to have lost most of its activity against the B.1.351 variant, raising concerns that the combination therapy might be less effective for some patients. The findings should alleviate concerns that vaccines will become ineffective but suggest the importance of continued surveillance for potential new variants.

Improving oligo-conjugated antibody signal in multimodal single-cell analysis

Simultaneous measurement of surface proteins and gene expression within single cells using oligo-conjugated antibodies offers high-resolution snapshots of complex cell populations. Signal from oligo-conjugated antibodies is quantified by high-throughput sequencing and is highly scalable and sensitive. We investigated the response of oligo-conjugated antibodies towards four variables: concentration, staining volume, cell number at staining, and tissue. We find that staining with recommended antibody concentrations causes unnecessarily high background and amount of antibody used can be drastically reduced without loss of biological information. Reducing staining volume only affects antibodies targeting abundant epitopes used at low concentrations and is counteracted by reducing cell numbers. Adjusting concentrations increases signal, lowers background, and reduces costs. Background signal can account for a major fraction of total sequencing and is primarily derived from antibodies used at high concentrations. This study provides new insight into titration response and background of oligo-conjugated antibodies and offers concrete guidelines to improve such panels.

Neutralization of viruses with European, South African, and United States SARS-CoV-2 variant spike proteins by convalescent sera and BNT162b2 mRNA vaccine-elicited antibodies

The increasing prevalence of SARS-CoV-2 variants with mutations in the spike protein has raised concerns that recovered individuals may not be protected from reinfection and that current vaccines will become less effective. The B.1.1.7 isolate identified in the United Kingdom and B.1.351 isolate identified in the Republic of South Africa encode spike proteins with multiple mutations in the S1 and S2 subunits. In addition, variants have been identified in Columbus, Ohio (COH.20G/677H), Europe (20A.EU2) and in domesticated minks. Analysis by antibody neutralization of pseudotyped viruses showed that convalescent sera from patients infected prior to the emergence of the variant viruses neutralized viruses with the B.1.1.7, B.1.351, COH.20G/677H Columbus Ohio, 20A.EU2 Europe and mink cluster 5 spike proteins with only a minor decrease in titer compared to that of the earlier D614G spike protein. Serum specimens from individuals vaccinated with the BNT162b2 mRNA vaccine neutralized D614G virus with titers that were on average 7-fold greater than convalescent sera. Vaccine elicited antibodies neutralized virus with the B.1.1.7 spike protein with titers similar to D614G virus and neutralized virus with the B.1.351 spike with, on average, a 3-fold reduction in titer (1:500), a titer that was still higher than the average titer with which convalescent sera neutralized D614G (1:139). The reduction in titer was attributable to the E484K mutation in the RBD. The B.1.1.7 and B.1.351 viruses were not more infectious than D614G on ACE2.293T cells in vitro but N501Y, an ACE2 contacting residue present in the B.1.1.7, B.1.351 and COH.20G/677H spike proteins caused higher affinity binding to ACE2, likely contributing to their increased transmissibility. These findings suggest that antibodies elicited by primary infection and by the BNT162b2 mRNA vaccine are likely to maintain protective efficacy against B.1.1.7 and most other variants but that the partial resistance of virus with the B.1.351 spike protein could render some individuals less well protected, supporting a rationale for the development of modified vaccines containing E484K.

Targeting TNFR2 to overcome acquired adaptive resistance to immune checkpoint blockade

Overcoming acquired adaptive immune resistance to anti-PD-1 therapy is imperative for enhancing the efficacy of immune checkpoint blockade (ICB) in solid tumors. Regulatory T cells (Tregs) play a prominent role in the suppressive tumor microenvironment (TME) and are major contributors to adaptive immune resistance. Tregs limit CD8+ T cell reinvigoration and are a promising target for combination therapy. While the clinical efficacy of anti-CTLA4 may be partially explained by restriction of Tregs, its co-administration with anti-PD1 causes significant toxicity. Thus, safer approaches to limit Treg activity are needed. To elucidate the dynamic changes in immuno-regulatory circuits within the TME during ICB, we performed deep immune profiling of peripheral blood and tumors from patients with advanced melanoma prior to (n=7) and after 1 cycle of anti-PD-1 therapy with pembrolizumab (n=9). Tregs were abundant in the TME and retained their immunosuppressive phenotype and functionality following anti-PD-1. Epigenetic, transcriptomic, and proteomic analysis of Tregs after ICB identified tumor necrosis factor receptor 2 (TNFR2) signaling as a possible driver of CD8+ T cell suppression. TNFR2 was preferentially expressed by Tregs in the TME (mean 18.03 %, SD +/− 10.13 %) relative to CD8+ T cells (mean 0.64 %, SD +/− 0.82 %) and peripheral Tregs (mean 3.16 %, SD +/− 3.21 %), suggesting it might be a safe and effective target for combination therapy. Indeed, dual blockade of TNFR2 and PD-1 led to potent CD8+ T cell expansion in two mouse tumor models, and restored sensitivity to ICB in a resistant murine model of melanoma. Our data suggest that anti-TNFR2 might synergize with current ICB by countering the development of adaptive immune resistance.

T cell intrinsic DNA damage and repair response as a novel marker associated with clinical response to PD-1 blockade

Despite the high tumor mutational burden (TMB), immune checkpoint blockade (ICB) still fails in some microsatellite instability-high (MSI-H) tumors, suggesting the underlying T cell dysfunction. Immune profiling of PBMC from chemotherapy-resistant MSI-H uterine cancer patients treated with nivolumab identified the proliferative T cell response 2–4 weeks post PD-1 blockade. However, this “immunological response” to ICB was observed regardless of clinical response, suggesting the additional determinants of clinical outcome beyond the proliferative response or high TMB. To test the hypothesis that the gap between immunological and clinical response to ICB was related to T celI-intrinsic response to genotoxic and/or proliferative stress, a novel high dimensional cytometry platform was developed. The platform enables simultaneous analysis of T cell differentiation state and interrogation of multiple DNA damage and repair response (DDR) pathways at single cell resolution. This DDR-Immune platform revealed consistent T cell subset specific patterns of DDR, as well as specific DDR pathways induced by different types of DNA damage. Application of the DDR-Immune platform to this cohort revealed that, in clinical responders, Ki67+ CD8 T cells had rapid increase of pATM, presumably in response to proliferative stress induced by PD-1 blockade. This DDR was not clearly observed in clinical non-responders. In addition, Tregs from clinical non-responders had elevated DDRs compared to responders, suggesting their greater resistance to genotoxic/proliferative stress. Collectively, the new platform reveals previously unrecognized roles for T cell-intrinsic DDR as a novel determinant of immune responsiveness and clinical outcome.

Abstract B80: High dimensional DNA damage and repair (DDR) cytometric profiling of human T cell subsets revealed distinct DDR signatures

DNA damage and repair (DDR) has been extensively studied in the context of inducing cell death of tumor cells. Tumor cells are often highly-proliferating and vulnerable to DNA damage, a foundation for many chemotherapy and radiotherapy approaches. Accumulating evidence indicates the improved clinical prognosis when immune checkpoint blockade (ICB) are combined with chemotherapy or radiotherapy. However, the paradox of the combinational benefit of these proliferation-targeting cytotoxic therapies and proliferation-inducing immunotherapies remains poorly understood. Here, we aimed to interrogate the impact of DNA damage on T cell differentiation and function to better understand the mechanism of the paradox, and to better interrogate how T cell-intrinsic DDR can impact clinical responses to ICBs. We hypothesized that T cell subsets have different DDR responses that contribute to distinct biological outcomes upon exposure to DNA damaging agents and/or proliferative stress induced by ICBs. To test this hypothesis, we developed a novel high dimensional cytometry platform that enables simultaneous analysis of T cell differentiation state and interrogation of multiple DDR pathways at single cell resolution. After introduction of DNA damage by γ-irradiation (IR), UV irradiation (UV) or proliferative stress (i.e. aCD3/28 stimulation) DNA damage accumulation and response varied depending on the state of T cell differentiation. For example, terminally differentiated effector cells (TEMRA) had significantly higher DNA damage accumulation and cell death. In contrast, stem cell memory (TSCM) and regulatory T cells (Treg) displayed high DDR with less cell death, suggesting perhaps better cell-intrinsic DDR against genotoxic stress. Overall, this platform revealed consistent, T cell subset specific patterns of DDR as well as specific DDR pathways induced by different types of DNA damage. DDR-Immune profiling of PBMC from uterine cancer patients treated with the combination of chemotherapy and ICB indicated the correlation between distinct patterns of DDR-Immune signatures and therapeutic response. Notably, in clinical responders, Ki67+ CD8 T cells responding to PD-1 blockade had increased pATM, perhaps in response to proliferative stress induced by PD-1 blockade. This increase in pATM was not observed in clinical non-responders. In addition, Treg from clinical non-responders had elevated DDR responses compared to responders, suggesting the possibility of greater resistance to genotoxic/proliferative stress. Collectively, our new platform shed lights on previously unrecognized roles of T cell-intrinsic DDR as a novel determinant of T cell differentiation and immune responsiveness. These findings may have relevance to apply to understanding the paradox of synergy of chemotherapy and radiotherapy with ICBs.

Citation Format: Yuki Muroyama, Alexander C. Huang, Sasikanth Manne, Ramin S. Herati, Lakshmi Chilukuri, Caiyue Xu, Claire F. Friedman, Dmitriy Zamarin, E. John Wherry. High dimensional DNA damage and repair (DDR) cytometric profiling of human T cell subsets revealed distinct DDR signatures [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2019 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(3 Suppl):Abstract nr B80.

TCF-1-Centered Transcriptional Network Drives an Effector versus Exhausted CD8 T Cell-Fate Decision

TCF-1 is a key transcription factor in progenitor exhausted CD8 T cells (Tex). Moreover, this Tex cell subset mediates responses to PD-1 checkpoint pathway blockade. However, the role of the transcription factor TCF-1 in early fate decisions and initial generation of Tex cells is unclear. Single-cell RNA sequencing (scRNA-seq) and lineage tracing identified a TCF-1+Ly108+PD-1+ CD8 T cell population that seeds development of mature Tex cells early during chronic infection. TCF-1 mediated the bifurcation between divergent fates, repressing development of terminal KLRG1Hi effectors while fostering KLRG1Lo Tex precursor cells, and PD-1 stabilized this TCF-1+ Tex precursor cell pool. TCF-1 mediated a T-bet-to-Eomes transcription factor transition in Tex precursors by promoting Eomes expression and drove c-Myb expression that controlled Bcl-2 and survival. These data define a role for TCF-1 in early-fate-bifurcation-driving Tex precursor cells and also identify PD-1 as a protector of this early TCF-1 subset.

T follicular helper cells in human efferent lymph retain lymphoid characteristics

T follicular helper cells (Tfh), a subset of CD4+ T cells, provide requisite help to B cells in the germinal centers (GC) of lymphoid tissue. GC Tfh are identified by high expression of the chemokine receptor CXCR5 and the inhibitory molecule PD-1. Although more accessible, blood contains lower frequencies of CXCR5+ and PD-1+ cells that have been termed circulating Tfh (cTfh). However, it remains unclear whether GC Tfh exit lymphoid tissues and populate this cTfh pool. To examine exiting cells, we assessed the phenotype of Tfh present within the major conduit of efferent lymph from lymphoid tissues into blood, the human thoracic duct. Unlike what was found in blood, we consistently identified a CXCR5-bright PD-1-bright (CXCR5BrPD-1Br) Tfh population in thoracic duct lymph (TDL). These CXCR5BrPD-1Br TDL Tfh shared phenotypic and transcriptional similarities with GC Tfh. Moreover, components of the epigenetic profile of GC Tfh could be detected in CXCR5BrPD-1Br TDL Tfh and the transcriptional imprint of this epigenetic signature was enriched in an activated cTfh subset known to contain vaccine-responding cells. Together with data showing shared TCR sequences between the CXCR5BrPD-1Br TDL Tfh and cTfh, these studies identify a population in TDL as a circulatory intermediate connecting the biology of Tfh in blood to Tfh in lymphoid tissue.

Identification and characterization of HIV-specific resident memory CD8+ T cells in human lymphoid tissue

Current paradigms of CD8⁺ T cell-mediated protection in HIV infection center almost exclusively on studies of peripheral blood, which is thought to provide a window into immune activity at the predominant sites of viral replication in lymphoid tissues (LTs). Through extensive comparison of blood, thoracic duct lymph (TDL), and LTs in different species, we show that many LT memory CD8⁺ T cells bear phenotypic, transcriptional, and epigenetic signatures of resident memory T cells (T_RMs). Unlike their circulating counterparts in blood or TDL, most of the total and follicular HIV-specific CD8⁺ T cells in LTs also resemble T_RMs Moreover, high frequencies of HIV-specific CD8⁺ T_RMs with skewed clonotypic profiles relative to matched blood samples are present in LTs of individuals who spontaneously control HIV replication in the absence of antiretroviral therapy (elite controllers). Single-cell RNA sequencing analysis confirmed that HIV-specific T_RMs are enriched for effector-related immune genes and signatures compared with HIV-specific non-T_RMs in elite controllers. Together, these data indicate that previous studies in blood have largely failed to capture the major component of HIV-specific CD8⁺ T cell responses resident within LTs.

A single dose of neoadjuvant PD-1 blockade predicts clinical outcomes in resectable melanoma

Immunologic responses to anti-PD-1 therapy in melanoma patients occur rapidly with pharmacodynamic T cell responses detectable in blood by 3 weeks. It is unclear, however, whether these early blood-based observations translate to the tumor microenvironment. We conducted a study of neoadjuvant/adjuvant anti-PD-1 therapy in stage III/IV melanoma. We hypothesized that immune reinvigoration in the tumor would be detectable at 3 weeks and this response would correlate with disease-free survival. We identified a rapid and potent anti-tumor response, with 8/27 patients experiencing a complete or major pathological response after a single dose of anti-PD-1, all of whom remain disease-free. These rapid pathologic and clinical responses were associated with accumulation of exhausted CD8 T cells in the tumor at 3 weeks with reinvigoration in the blood observed as early as 1 week. Transcriptional analysis demonstrated a pre-treatment immune signature (Neoadjuvant Response Signature) that was associated with clinical benefit. In contrast, patients with disease recurrence displayed mechanisms of resistance including immune suppression, mutational escape, and/or tumor evolution. Neoadjuvant anti-PD-1 treatment is effective in high-risk resectable stage III/IV melanoma. Pathological response and immunological analyses after a single neoadjuvant dose can be used to predict clinical outcome and to dissect underlying mechanisms in checkpoint blockade.

Spatial distribution and function of T follicular regulatory cells in human lymph nodes

T follicular regulatory (Tfr) cells are a population of CD4⁺ T cells that express regulatory T cell markers and have been shown to suppress humoral immunity. However, the precise mechanisms and location of Tfr-mediated suppression in the lymph node (LN) microenvironment are unknown. Using highly multiplexed quantitative imaging and functional assays, we examined the spatial distribution, suppressive function, and preferred interacting partners of Tfr cells in human mesenteric LNs. We find that the majority of Tfr cells express low levels of PD-1 and reside at the border between the T cell zone and B cell follicle, with very few found in the germinal centers (GCs). Although PD-1⁺ Tfr cells expressed higher levels of CD38, CTLA-4, and GARP than PD-1^Neg Tfr cells, both potently suppressed antibody production in vitro. These findings highlight the phenotypic diversity of human Tfr cells and suggest that Tfr-mediated suppression is most efficient at the T-B border and within the follicle, not in the GC.

CD4+ T Cell Differentiation in Chronic Viral Infections: The Tfh Perspective

CD4+ T cells play a critical role in the response to chronic viral infections during the acute phase and in the partial containment of infections once chronic infection is established. As infection persists, the virus-specific CD4+ T cell response begins to shift in phenotype. The predominant change described in both mouse and human studies of chronic viral infection is a decrease in detectable T helper type (Th)1 responses. Some Th1 loss is due to decreased proliferative potential and decreased cytokine production in the setting of chronic antigen exposure. However, recent data suggest that Th1 dysfunction is accompanied by a shift in the differentiation pathway of virus-specific CD4+ T cells, with enrichment for cells with a T follicular helper cell (Tfh) phenotype. A Tfh-like program during chronic infection has now been identified in virus-specific CD8+ T cells as well. In this review, we discuss what is known about CD4+ T cell differentiation in chronic viral infections, with a focus on the emergence of the Tfh program and the implications of this shift with respect to Tfh function and the host-pathogen interaction.

Human T follicular regulatory cells (Tfr) able to inhibit antibody production are enriched at the lymph node T-B border and rare in germinal centers

T follicular helper (Tfh) cells are a subset of CD4+ T cells that are critical for the formation of germinal centers (GCs) and the development of high affinity, class-switched antibodies. Tfh cells are differentiated in a Bcl6-dependent manner and are characterized by expression of the inhibitory receptor PD-1 along with CXCR5, a chemokine receptor that directs these cells to the follicle. More recently, T follicular regulatory cells (Tfr) have been shown to express regulatory T cell (Treg) markers and suppress humoral immunity. To date, much of our understanding of the function and distribution of Tfh and Tfr cells has been obtained from animal studies. Using highly multiplexed, quantitative imaging and functional assays, we examined the spatial distribution and suppressive function of human Tfr cells obtained from mesenteric lymph nodes. Here, we report that the majority of Tfr cells reside at the border between the T cell zone and B cell follicle and are rare within the GC, being far outnumbered by Tfh cells. In contrast to Tfh cells, Tfr cells expressed low to undetectable levels of PD-1 in situ yet potently suppressed antibody production in vitro. These findings reveal that Tfh and Tfr cells are spatially segregated within human lymph nodes and caution against using PD-1 expression levels as a phenotypic marker for human Tfr cells.

This research was supported in part by NIH R01, VA, and Intramural Research Program of the NIH, NIAID.

T-cell invigoration to tumour burden ratio associated with anti-PD-1 response

Despite the success of monotherapies based on blockade of programmed cell death 1 (PD-1) in human melanoma, most patients do not experience durable clinical benefit. Pre-existing T-cell infiltration and/or the presence of PD-L1 in tumours may be used as indicators of clinical response; however, blood-based profiling to understand the mechanisms of PD-1 blockade has not been widely explored. Here we use immune profiling of peripheral blood from patients with stage IV melanoma before and after treatment with the PD-1-targeting antibody pembrolizumab and identify pharmacodynamic changes in circulating exhausted-phenotype CD8 T cells (T_ex cells). Most of the patients demonstrated an immunological response to pembrolizumab. Clinical failure in many patients was not solely due to an inability to induce immune reinvigoration, but rather resulted from an imbalance between T-cell reinvigoration and tumour burden. The magnitude of reinvigoration of circulating T_ex cells determined in relation to pretreatment tumour burden correlated with clinical response. By focused profiling of a mechanistically relevant circulating T-cell subpopulation calibrated to pretreatment disease burden, we identify a clinically accessible potential on-treatment predictor of response to PD-1 blockade.

Abstract PR05: Peripheral blood immune profiling of anti-PD-1 therapy in human melanoma reveals a link between T cell re-invigoration and tumor burden that predicts response

Despite the clinical success of PD-1 based therapies in human melanoma patients, the majority of patients do not have durable clinical benefit from anti-PD-1 monotherapy. A major challenge remains identifying which patients will respond to anti-PD-1 therapy and defining the underlying reasons for successful response versus treatment failure. Pre-existing T cell infiltration and/or PD-L1 expression in tumors may predict clinical responses; however, the use of blood-based profiling to understand the immunologic mechanism of PD-1 blockade has been less explored. Here we used detailed immune profiling of peripheral blood from stage IV melanoma patients before and after pembrolizumab (pembro), and identified pharmacodynamic changes in circulating exhausted-phenotype CD8 T cells (TEX). Robust induction of Ki67 in this subset of circulating CD8 T cells post-therapy (re-invigoration) occurred in 78% of patients indicating strong, on target immunological effects of PD-1 blockade in most patients studied here. Despite this high immunological response rate, the objective clinical response rate in this cohort was less than 40%. Ki67 in CD8 T cells alone did not predict clinical outcomes and, in fact, higher systemic immune activation at baseline was associated with lower overall survival. Rather, the magnitude of re-invigoration of circulating TEX in relation to pre-treatment tumor burden correlated with clinical response. We identified a TEX re-invigoration to tumor burden ratio which could be used to predict clinical response and overall survival as early as 6 weeks post therapy. Consistent observations were found in a second independent cohort and suggest that clinical failure of PD-1 blockade in many patients may not solely be due to an inability to induce immune re-invigoration but rather, an imbalance between T cell re-invigoration and tumor burden. Thus, by focused profiling of a mechanistically relevant circulating T cell subpopulation calibrated to pre-treatment disease burden, we identify a clinically accessible predictor of response to PD-1 blockade. These findings also provide a framework for dissecting distinct types of treatment failures in melanoma and have implications for stratifying patients into additional immunotherapeutic treatment approaches.

Citation Format: Alexander Huang, Michael A. Postow, Robert J. Orlowski, Rosemarie Mick, Bertram Bengsch, Sasi Manne, Wei Xu, Shannon Harmon, Matthew Adamow, Deborah Kuk, Katherine Panangeas, Cristina Carerra, Phillip Wong, Felix Quagliarello, Kristen E. Pauken, Ramin S. Herati, Suzanne McGettigan, Shawn Kothari, Sangeeth M. George, Brandon Wenz, Kurt D'Andrea, Xiaowei Xu, Ravi K. Amaravadi, Giorgos Karakousis, Lynn M. Schuchter, Katherine L. Nathanson, Jedd D. Wolchok, Tara C. Gangadhar, John Wherry. Peripheral blood immune profiling of anti-PD-1 therapy in human melanoma reveals a link between T cell re-invigoration and tumor burden that predicts response [abstract]. In: Proceedings of the Second CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; 2016 Sept 25-28; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(11 Suppl):Abstract nr PR05.

ICOS+CD38+ cTfh in peripheral blood and thoracic duct lymph

T follicular helper cells provide essential B cell help within the germinal center (GC), and these cells have been shown to populate the follicular mantel once the GC reaction is complete. The significance and ontology of circulating Tfh (cTfh) is less clear. Studies in humans have suggested subsets of cTfh that correlate with humoral responses in chronic infection (HIV, malaria) and in response to acute challenge (influenza vaccination). We have previously described a subset of CXCR5+PD1+ cTfh that expresses both ICOS and CD38. This population was significantly increased 7 days after influenza vaccination as well as in patients infected with HIV. Single cell transcriptional analysis of the ICOS+CD38+ cTfh after influenza vaccination demonstrated more frequent expression of the GC Tfh transcripts CMAF, BCL6, and CD200 than was found in the ICOS−CD38− cTfh, and bulk transcriptional analysis indicated higher expression of IL-21. These data suggested that ICOS and CD38 mark the rare population of cTfh that are more recent émigrés from the lymph nodes. To evaluate this possibility, we analyzed Tfh in an immune compartment that is more proximal to the lymph nodes than peripheral blood: thoracic duct lymph (TDL). As expected, TDL Tfh had a higher frequency of ICOS+CD38+ cells than cTfh in matched peripheral blood. In addition, TDL had a population of CXCR5+PD1bright Tfh, previously only identified in lymphoid tissues. CXCR5+PD1bright Tfh in the TDL had a significantly increased frequency of ICOS+CD38+ cells. These data provide a critical missing link in the understanding of cTfh and suggest that the ICOS+CD38+ cTfh subset warrants further exploration as peripheral surrogates of the active immune responses within secondary lymphoid tissues.

Abstract 2858: Radiation and dual immune checkpoint blockade overcome tumor resistance and distinctly improve immunity

Optimal results with immune checkpoint inhibitors such as CTLA4 and PD-1 will likely require combination therapy. This raises important questions about tumor resistance and non-redundant mechanisms of action. Pre-clinical and clinical data indicate that radiation (RT) may augment responses to immune checkpoint inhibition. We therefore evaluated this combination for metastatic melanoma using parallel studies in mice and humans. In a phase I clinical trial with 19 patients with multiple melanoma metastases, a single index lesion was irradiated with hypofractionated RT, delivered over two or three fractions, followed by four cycles of the anti-CTLA4 antibody ipilimumab. We reproduced this therapy in mice using the melanoma cell line B16-F10. For this, each flank of C57BL/6 mice was implanted with tumors to model multiple metastases. Mice received anti-CTLA4 (on days 5, 8, and 11), irradiation of one tumor using an image-guided micro-irradiator (20 Gy x 1 on day 8), or both treatments. Mechanistic studies were performed on material obtained from patients and mice at baseline and thereafter. Overall, treatment in the phase I study was well tolerated and toxicity was similar to that reported for anti-CTLA4. Major tumor regressions were observed in a subset of patients with metastatic melanoma treated with anti-CTLA4 + RT. In mice, although combined treatment enhanced the CD8 T cell to Treg ratios and improved responses in irradiated and unirradiated tumors, resistance was common. Genome-wide and unbiased analyses revealed that resistant tumors have increased PD-L1, interferon-stimulated genes, and exhausted T cells that depress the CD8/Treg ratio. Patients and mice with high PD-L1 tumors that were treated with RT + anti-CTLA4 poorly reinvigorated exhausted T cells, did not respond, and rapidly progressed. In mice, adding anti-PD-L1/PD-1 to RT + anti-CTLA4 reinvigorated exhausted T cells, leading to complete responses and immunity across multiple cancer types. The extent of T cell exhaustion/reinvigoration predicts response and can be assessed through peripheral blood. Resistance to RT + anti-CTLA4 results from depression in the CD8/Treg ratio due to elevated tumor PD-L1 and persistent T cell exhaustion. Both clinical and pre-clinical data suggest that the combination of RT with CTLA4 and PD-1 checkpoint blockade is a rational, non-redundant approach to overcoming tumor resistance and improving immunity in multiple cancer types.

Citation Format: Andrew J. Rech, Christina Twyman-Saint Victor, Amit Maity, Ramesh Rengan, Kristen E. Pauken, Erietta Stelekati, Joseph Benci, Bihui Xu, Hannah Dada, Pamela M. Odorizzi, Ramin S. Herati, Kathleen D. Mansfield, Dana Patsch, Ravi K. Amaravadi, Lynn M. Schuchter, Hemant Ishwaran, Rosemarie Mick, Daniel Pryma, Xiaowei Xu, Michael D. Feldman, Tara C. Gangadhar, Stephen M. Hahn, E. John Wherry, Andy J. Minn, Robert H. Vonderheide. Radiation and dual immune checkpoint blockade overcome tumor resistance and distinctly improve immunity. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2858. doi:10.1158/1538-7445.AM2015-2858

Radiation and dual checkpoint blockade activate non-redundant immune mechanisms in cancer

Immune checkpoint inhibitors¹ result in impressive clinical responses^2–5 but optimal results will require combination with each other⁶ and other therapies. This raises fundamental questions about mechanisms of non-redundancy and resistance. Here, we report major tumor regressions in a subset of patients with metastatic melanoma treated with an anti-CTLA4 antibody (anti-CTLA4) and radiation (RT) and reproduced this effect in mouse models. Although combined treatment improved responses in irradiated and unirradiated tumors, resistance was common. Unbiased analyses of mice revealed that resistance was due to upregulation of PD-L1 on melanoma cells and associated with T cell exhaustion. Accordingly, optimal response in melanoma and other cancer types requires RT, anti-CTLA4, and anti-PD-L1/PD-1. Anti-CTLA4 predominantly inhibits T regulatory cells (Tregs) to increase the CD8 T cell to Treg (CD8/Treg) ratio. RT enhances the diversity of the T cell receptor (TCR) repertoire of intratumoral T cells. Together, anti-CTLA4 promotes expansion of T cells, while RT shapes the TCR repertoire of the expanded peripheral clones. Addition of PD-L1 blockade reverses T cell exhaustion to mitigate depression in the CD8/Treg ratio and further encourages oligo-clonal T cell expansion. Similar to results from mice, patients on our clinical trial with melanoma showing high PD-L1 did not respond to RT + anti-CTLA4, demonstrated persistent T cell exhaustion, and rapidly progressed. Thus, PD-L1 on melanoma cells allows tumors to escape anti-CTLA4-based therapy, and the combination of RT, anti-CTLA4, and anti-PD-L1 promotes response and immunity through distinct mechanisms.

Hepatitis C virus testing in adults living with HIV: a need for improved screening efforts

OBJECTIVES

Guidelines recommend hepatitis C virus (HCV) screening for all people living with HIV (PLWH). Understanding HCV testing practices may improve compliance with guidelines and can help identify areas for future intervention.

METHODS

We evaluated HCV screening and unnecessary repeat HCV testing in 8,590 PLWH initiating care at 12 U.S. HIV clinics between 2006 and 2010, with follow-up through 2011. Multivariable logistic regression examined the association between patient factors and the outcomes: HCV screening (≥1 HCV antibody tests during the study period) and unnecessary repeat HCV testing (≥1 HCV antibody tests in patients with a prior positive test result).

RESULTS

Overall, 82% of patients were screened for HCV, 18% of those screened were HCV antibody-positive, and 40% of HCV antibody-positive patients had unnecessary repeat HCV testing. The likelihood of being screened for HCV increased as the number of outpatient visits rose (adjusted odds ratio 1.02, 95% confidence interval 1.01-1.03). Compared to men who have sex with men (MSM), patients with injection drug use (IDU) were less likely to be screened for HCV (0.63, 0.52-0.78); while individuals with Medicaid were more likely to be screened than those with private insurance (1.30, 1.04-1.62). Patients with heterosexual (1.78, 1.20-2.65) and IDU (1.58, 1.06-2.34) risk compared to MSM, and those with higher numbers of outpatient (1.03, 1.01-1.04) and inpatient (1.09, 1.01-1.19) visits were at greatest risk of unnecessary HCV testing.

CONCLUSIONS

Additional efforts to improve compliance with HCV testing guidelines are needed. Leveraging health information technology may increase HCV screening and reduce unnecessary testing.

Localized hepatosplenic sarcoidosis with an elevated serum CA-125 level

Sarcoidosis, a granulomatous disorder of unknown etiology, primarily affects the lungs and lymph nodes. Extrapulmonary disease without any pulmonary involvement is rare. Sarcoidosis with an elevated serum CA-125 level has only been reported five times in the literature. We describe a case of localized hepatosplenic sarcoidosis, confirmed by biopsy, with associated CA-125 elevation. In our review of the current literature, this is the first reported case of localized hepatosplenic sarcoidosis with associated serum CA-125 elevation.

Liver-directed neonatal gene therapy prevents cardiac, bone, ear, and eye disease in mucopolysaccharidosis I mice

Mucopolysaccharidosis I (MPS I) due to deficient alpha-L-iduronidase (IDUA) activity results in accumulation of glycosaminoglycans in many cells. Gene therapy could program liver to secrete enzyme with mannose 6-phosphate (M6P), and enzyme in blood could be taken up by other cells via the M6P receptor. Newborn MPS I mice were injected with 10(9) (high dose) or 10(8) (low dose) transducing units/kg of a retroviral vector (RV) expressing canine IDUA. Most animals achieved stable expression of IDUA in serum at 1240 +/- 147 and 110 +/- 31 units/ml, respectively. At 8 months, untreated MPS I mice had aortic insufficiency, increased bone mineral density (BMD), and reduced responses to sound and light. In contrast, MPS I mice that received high-dose RV had normal echocardiograms, BMD, auditory-evoked brain-stem responses, and electroretinograms. This is the first report of complete correction of these clinical manifestations in any model of mucopolysaccharidosis. Biochemical and pathologic evaluation confirmed that storage was reduced in these organs. Mice that received low-dose RV and achieved 30 units/ml of serum IDUA activity had no or only partial improvement. We conclude that high-dose neonatal gene therapy with an RV reduces some major clinical manifestations of MPS I in mice, but low dose is less effective.