Postoperative C5 Palsy after Anterior or Posterior Decompression for Degenerative Cervical Myelopathy: A Subgroup Analysis of the Multicenter, Prospective, Randomized, Phase III, CSM-Protect Clinical Trial

STUDY DESIGN

Retrospective cohort study of prospectively accrued data.

OBJECTIVE

To evaluate a large, prospective, multicentre dataset of surgically-treated DCM cases on the contemporary risk of C5 palsy with surgical approach.

SUMMARY OF BACKGROUND DATA

The influence of surgical technique on postoperative C5 palsy after decompression for degenerative cervical myelopathy (DCM) is intensely debated. Comprehensive analyses are needed using contemporary data and accounting for covariates.

METHODS

Patients with moderate to severe DCM were prospectively enrolled in the multicenter, randomized CSM-Protect clinical trial and underwent either anterior or posterior decompression between Jan 31, 2012, to May 16, 2017. The primary outcome was the incidence of postoperative C5 palsy, defined as onset of muscle weakness by at least one grade in manual muscle test at the C5 myotome with slight or absent sensory disruption after cervical surgery. Two comparative cohorts were made based on anterior or posterior surgical approach. Multivariate hierarchical mixed-effects logistic regression was used to estimate odds ratios (OR) with 95% confidence intervals (CI) for C5 palsy.

RESULTS

A total of 283 patients were included, and 53.4% underwent posterior decompression. The total incidence of postoperative C5 palsy was 7.4% and was significantly higher in patients that underwent posterior decompression compared to anterior decompression (11.26% vs. 3.03%, P=0.008). After multivariable regression, posterior approach was independently associated with greater than four times the likelihood of postoperative C5 palsy (P=0.017). Rates of C5 palsy recovery were comparable between the two surgical approaches.

CONCLUSION

The odds of postoperative C5 palsy are significantly higher after posterior decompression compared to anterior decompression for DCM. This may influence surgical decision-making when there is equipoise in deciding between anterior and posterior treatment options for DCM.

LEVEL OF EVIDENCE

Therapeutic Level II.

Innate Responses to the Former COVID-19 Vaccine Candidate CVnCoV and Their Relation to Reactogenicity and Adaptive Immunogenicity

Vaccines are highly effective at preventing severe coronavirus disease (COVID-19). With mRNA vaccines, further research is needed to understand the association between immunogenicity and reactogenicity, which is defined as the physical manifestation of an inflammatory response to a vaccination. This study analyzed the immune response and reactogenicity in humans, post immunization, to the former SARS-CoV-2 mRNA investigational vaccine CVnCoV (CV-NCOV-001 and CV-NCOV-002 clinical trials). Immunogenicity was investigated using whole-blood RNA sequencing, serum cytokine levels, and SARS-CoV-2-specific antibodies. The T cell responses in peripheral blood were assessed using intracellular cytokine staining (ICS) and high-dimensional profiling in conjunction with SARS-CoV-2 antigen-specificity testing via mass cytometry. Reactogenicity was graded after participants' first and second doses of CVnCoV using vaccine-related solicited adverse events (AEs). Finally, a Spearman correlation was performed between reactogenicity, humoral immunity, and serum cytokine levels to assess the relationship between reactogenicity and immunogenicity post CVnCoV vaccination. Our findings showed that the gene sets related to innate and inflammatory immune responses were upregulated one day post CVnCoV vaccination, while the gene sets related to adaptive immunity were upregulated predominantly one week after the second dose. The serum levels of IFNα, IFNγ, IP-10, CXCL11, IL-10, and MCP-1 increased transiently, peaking one day post vaccination. CD4+ T cells were induced in all vaccinated participants and low frequencies of CD8+ T cells were detected by ex vivo ICS. Using mass cytometry, SARS-CoV-2 spike-specific CD8+ T cells were induced and were characterized as having an activated effector memory phenotype. Overall, the results demonstrated a positive correlation between vaccine-induced systemic cytokines, reactogenicity, and adaptive immunity, highlighting the importance of the balance between the induction of innate immunity to achieve vaccine efficacy and ensuring low reactogenicity.

PeptiVAX: A new adaptable peptides-delivery platform for development of CTL-based, SARS-CoV-2 vaccines

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) posed a threat to public health and the global economy, necessitating the development of various vaccination strategies. Mutations in the SPIKE protein gene, a crucial component of mRNA and adenovirus-based vaccines, raised concerns about vaccine efficacy, prompting the need for rapid vaccine updates. To address this, we leveraged PeptiCRAd, an oncolytic vaccine based on tumor antigen decorated oncolytic adenoviruses, creating a vaccine platform called PeptiVAX. First, we identified multiple CD8 T-cell epitopes from highly conserved regions across coronaviruses, expanding the range of T-cell responses to non-SPIKE proteins. We designed short segments containing the predicted epitopes presented by common HLA-Is in the global population. Testing the immunogenicity, we characterized T-cell responses to candidate peptides in peripheral blood mononuclear cells (PBMCs) from pre-pandemic healthy donors and ICU patients. As a proof of concept in mice, we selected a peptide with epitopes predicted to bind to murine MHC-I haplotypes. Our technology successfully elicited peptide-specific T-cell responses, unaffected by the use of unarmed adenoviral vectors or adeno-based vaccines encoding SPIKE. In conclusion, PeptiVAX represents a fast and adaptable SARS-CoV-2 vaccine delivery system that broadens T-cell responses beyond the SPIKE protein, offering potential benefits for vaccine effectiveness.

Combination of oligo-fractionated irradiation with nivolumab can induce immune modulation in gastric cancer

BACKGROUND

Tumor-associated antigen (TAA)-specific CD8(+) T cells are essential for nivolumab therapy, and irradiation has been reported to have the potential to generate and activate TAA-specific CD8(+) T cells. However, mechanistic insights of T-cell response during combinatorial immunotherapy using radiotherapy and nivolumab are still largely unknown.

METHODS

Twenty patients included in this study were registered in the CIRCUIT trial (ClinicalTrials.gov, NCT03453164). All patients had multiple distant metastases and were intolerance or had progressed after primary and secondary chemotherapy without any immune checkpoint inhibitor. In the CIRCUIT trial, eligible patients were treated with a total of 22.5 Gy/5 fractions/5 days of radiotherapy to the largest or symptomatic lesion prior to receiving nivolumab every 2 weeks. In these 20 patients, T-cell responses during the combinatorial immunotherapy were monitored longitudinally by high-dimensional flow cytometry-based, multiplexed major histocompatibility complex multimer analysis using a total of 46 TAAs and 10 virus epitopes, repertoire analysis of T-cell receptor β-chain (TCRβ), together with circulating tumor DNA analysis to evaluate tumor mutational burden (TMB).

RESULTS

Although most TAA-specific CD8(+) T cells could be tracked longitudinally, several TAA-specific CD8(+) T cells were detected de novo after irradiation, but viral-specific CD8(+) T cells did not show obvious changes during treatment, indicating potential irradiation-driven antigen spreading. Irradiation was associated with phenotypical changes of TAA-specific CD8(+) T cells towards higher expression of killer cell lectin-like receptor subfamily G, member 1, human leukocyte antigen D-related antigen, T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domain, CD160, and CD45RO together with lower expression of CD27 and CD127. Of importance, TAA-specific CD8(+) T cells in non-progressors frequently showed a phenotype of CD45RO(+)CD27(+)CD127(+) central memory T cells compared with those in progressors. TCRβ clonality (inverted Pielou's evenness) increased and TCRβ diversity (Pielou's evenness and Diversity Evenness score) decreased during treatment in progressors (p=0.029, p=0.029, p=0.012, respectively). TMB score was significantly lower in non-progressors after irradiation (p=0.023).

CONCLUSION

Oligo-fractionated irradiation induces an immune-modulating effect with potential antigen spreading and the combination of radiotherapy and nivolumab may be effective in a subset of patients with gastric cancer.

Impaired communication at the neuromotor axis during Degenerative Cervical Myelopathy

Degenerative Cervical Myelopathy (DCM) is a progressive neurological condition characterized by structural alterations in the cervical spine, resulting in compression of the spinal cord. While clinical manifestations of DCM are well-documented, numerous unanswered questions persist at the molecular and cellular levels. In this study, we sought to investigate the neuromotor axis during DCM. We use a clinically relevant mouse model, where after 3 months of DCM induction, the sensorimotor tests revealed a significant reduction in both locomotor activity and muscle strength compared to the control group. Immunohistochemical analyses showed alterations in the gross anatomy of the cervical spinal cord segment after DCM. These changes were concomitant with the loss of motoneurons and a decrease in the number of excitatory synaptic inputs within the spinal cord. Additionally, the DCM group exhibited a reduction in the endplate surface, which correlated with diminished presynaptic axon endings in the supraspinous muscles. Furthermore, the biceps brachii (BB) muscle exhibited signs of atrophy and impaired regenerative capacity, which inversely correlated with the transversal area of remnants of muscle fibers. Additionally, metabolic assessments in BB muscle indicated an increased proportion of oxidative skeletal muscle fibers. In line with the link between neuromotor disorders and gut alterations, DCM mice displayed smaller mucin granules in the mucosa layer without damage to the epithelial barrier in the colon. Notably, a shift in the abundance of microbiota phylum profiles reveals an elevated Firmicutes-to-Bacteroidetes ratio-a consistent hallmark of dysbiosis that correlates with alterations in gut microbiota-derived metabolites. Additionally, treatment with short-chain fatty acids stimulated the differentiation of the motoneuron-like NSC34 cell line. These findings shed light on the multifaceted nature of DCM, resembling a synaptopathy that disrupts cellular communication within the neuromotor axis while concurrently exerting influence on other systems. Notably, the colon emerges as a focal point, experiencing substantial perturbations in both mucosal barrier integrity and the delicate balance of intestinal microbiota.

Combinatorial Hypofractionated Radiotherapy and Pembrolizumab in Anaplastic Thyroid Cancer

Objectives Anaplastic thyroid cancer (ATC) is an aggressive disease associated with poor outcomes and resistance to therapies. Our study aim was to evaluate the activity of a combinatorial regimen of sandwich sequencing of pembrolizumab immunotherapy and hypofractionated radiotherapy (RT). Methods In this case series, patients with ATC received hypofractionated RT (QUAD-shot) and intravenous pembrolizumab 200mg every 3-4 weeks. Pembrolizumab was continued until disease progression or up till 24 months. Concurrent Lenvatinib treatment was allowed. Primary endpoint was best overall response (BOR) and progression-free survival (PFS). Additionally, we performed immune profiling of circulating T cells in a responder to investigate the immune response to our combinatorial treatment. Results At median follow-up of 32.6 months (IQR: 26.4-38.8), of a cohort of 5 patients, BOR was 80%; with 2 complete responses (CR) and 2 partial responses (PR). Patients who achieved CR remained disease-free at last follow-up. Median PFS was 7.6 months (IQR: 6.2-NR), and 1-year PFS and overall survival rate was 40% (95% CI: 13.7-100) for both. Treatment was well-tolerated, with mostly grade 1-2 adverse events. Immune profiling of one partial responder revealed an increase in activated CD4 and CD8 T cells post-QUAD-shot RT, which was further enhanced during the maintenance phase of pembrolizumab. Conclusions Herein, we reported a case series of 5 patients with ATC, with 2 long-term survivors who were treated with surgical debulking followed by QUAD-shot RT and pembrolizumab, possibly due to synergy of local and systemic treatments in activating anti-tumour immunogenic cytotoxicity. This regimen warrants further investigation in a larger cohort of patients.

In-depth analysis of human virus-specific CD8+ T cells delineates unique phenotypic signatures for T cell specificity prediction

Following viral infection, the human immune system generates CD8+ T cell responses to virus antigens that differ in specificity, abundance, and phenotype. A characterization of virus-specific T cell responses allows one to assess infection history and to understand its contribution to protective immunity. Here, we perform in-depth profiling of CD8+ T cells binding to CMV-, EBV-, influenza-, and SARS-CoV-2-derived antigens in peripheral blood samples from 114 healthy donors and 55 cancer patients using high-dimensional mass cytometry and single-cell RNA sequencing. We analyze over 500 antigen-specific T cell responses across six different HLA alleles and observed unique phenotypes of T cells specific for antigens from different virus categories. Using machine learning, we extract phenotypic signatures of antigen-specific T cells, predict virus specificity for bulk CD8+ T cells, and validate these predictions, suggesting that machine learning can be used to accurately predict antigen specificity from T cell phenotypes.

Hospital spending and length of stay attributable to perioperative adverse events for inpatient hip, knee, and spine surgery: a retrospective cohort study

BACKGROUND

The incremental hospital cost and length of stay (LOS) associated with adverse events (AEs) has not been well characterized for planned and unplanned inpatient spine, hip, and knee surgeries.

METHODS

Retrospective cohort study of hip, knee, and spine surgeries at an academic hospital in 2011-2012. Adverse events were prospectively collected for 3,063 inpatient cases using the Orthopaedic Surgical AdVerse Event Severity (OrthoSAVES) reporting tool. Case costs were retrospectively obtained and inflated to equivalent 2021 CAD values. Propensity score methodology was used to assess the cost and LOS attributable to AEs, controlling for a variety of patient and procedure factors.

RESULTS

The sample was 55% female and average age was 64; 79% of admissions were planned. 30% of cases had one or more AEs (82% had low-severity AEs at worst). The incremental cost and LOS attributable to AEs were $8,500 (95% confidence interval [CI]: 5100-11,800) and 4.7 days (95% CI: 3.4-5.9) per admission. This corresponded to a cumulative $7.8 M (14% of total cohort cost) and 4,290 bed-days (19% of cohort bed-days) attributable to AEs. Incremental estimates varied substantially by (1) admission type (planned: $4,700/2.4 days; unplanned: $20,700/11.5 days), (2) AE severity (low: $4,000/3.1 days; high: $29,500/11.9 days), and (3) anatomical region (spine: $19,800/9 days; hip: $4,900/3.8 days; knee: $1,900/1.5 days). Despite only 21% of admissions being unplanned, adverse events in these admissions cumulatively accounted for 59% of costs and 62% of bed-days attributable to AEs.

CONCLUSIONS

This study comprehensively demonstrates the considerable cost and LOS attributable to AEs in orthopaedic and spine admissions. In particular, the incremental cost and LOS attributable to AEs per admission were almost five times as high among unplanned admissions compared to planned admissions. Mitigation strategies focused on unplanned surgeries may result in significant quality improvement and cost savings in the healthcare system.

Demographics, Mechanism of Injury, and Outcomes for Acute Upper and Lower Cervical Spinal Cord Injuries: An Analysis of 470 Patients in the Prospective, Multi-Center, North American Clinical Trials Network Registry

There is a paucity of data comparing the demographics, mechanism of injury, and outcomes of upper versus lower cervical spinal cord injuries (cSCI). The study objective was to define different clinical manifestations of cSCI. Data were collected prospectively through centers of the North American Clinical Trials Network (NACTN). Data was collected on 470 patients (21% women, mean age 50 years). Cervical vertebral level was analyzed as an ordinal variable to determine a natural demarcation to classify upper versus lower cSCI. For continuous variable analysis, falls were associated with C3 more than C4 vertebral level injuries (60% vs. 42%; p = 0.0126), while motor vehicle accidents were associated with C4 more than C3 (40% vs. 29%; p = 0.0962). Motor International Standards for Neurological Classification of Spinal Cord Injury scores also demonstrated a natural demarcation between C3 and C4, with C3 having higher median American Spinal Injury Association (ASIA) motor scores (40 [4-73] vs. 11 [3-59], p = 0.0227). There were no differences when comparing C2 to C3 nor C4 to C5. Given the significant differences seen between C3 and C4, but not C2 and C3 nor C4 and C5, upper cSCI was designated as C1-C3, and lower cSCI was designated as C4-C7. Compared with a lower cSCI, patients with an upper cSCI were more likely to have a fall as their mechanism of injury (54% vs. 36%; p = 0.0072). Patients with an ASIA C cSCI were likely to have an upper cervical injury: 23% vs. 11% (p = 0.0226). Additionally, patients with an upper cSCI were more likely to have diabetes prior to injury: 37% versus 22%, respectively (p = 0.0084). Lower cSCI were more likely injured through sports (19% vs. 8%, p = 0.0171) and present with ASIA A (42% vs. 25%, p = 0.0186) neurological grade. Patients with lower cSCI were also significantly more likely to have complications such as shock, pulmonary embolism, and pleural effusion. In conclusion, there appears to be a natural demarcation of injury type between C3 and C4. Upper cSCI (C1-C3) was more associated with falls and diabetes, whereas lower cSCI (C4-C7) was more associated with sports, worse ASIA scores, and more complications. Further research will be needed to understand the mechanistic and biological differences between these two groups and whether different treatments may be appropriate for each of these groups.

Longitudinal high-dimensional analysis identifies immune features associating with response to anti-PD-1 immunotherapy

Response to immunotherapy widely varies among cancer patients and identification of parameters associating with favourable outcome is of great interest. Here we show longitudinal monitoring of peripheral blood samples of non-small cell lung cancer (NSCLC) patients undergoing anti-PD1 therapy by high-dimensional cytometry by time of flight (CyTOF) and Meso Scale Discovery (MSD) multi-cytokines measurements. We find that higher proportions of circulating CD8+ and of CD8+CD101hiTIM3+ (CCT T) subsets significantly correlate with poor clinical response to immune therapy. Consistently, CD8+ T cells and CCT T cell frequencies remain low in most responders during the entire multi-cycle treatment regimen; and higher killer cell lectin-like receptor subfamily G, member 1 (KLRG1) expression in CCT T cells at baseline associates with prolonged progression free survival. Upon in vitro stimulation, CCT T cells of responders produce significantly higher levels of cytokines, including IL-1β, IL-2, IL-8, IL-22 and MCP-1, than of non-responders. Overall, our results provide insights into the longitudinal immunological landscape underpinning favourable response to immune checkpoint blockade therapy in lung cancer patients.

Radiotherapy for Mobile Spine and Sacral Chordoma: A Critical Review and Practical Guide from the Spine Tumor Academy

Chordomas are rare tumors of the embryologic spinal cord remnant. They are locally aggressive and typically managed with surgery and either adjuvant or neoadjuvant radiation therapy. However, there is great variability in practice patterns including radiation type and fractionation regimen, and limited high-level data to drive decision making. The purpose of this manuscript was to summarize the current literature specific to radiotherapy in the management of spine and sacral chordoma and to provide practice recommendations on behalf of the Spine Tumor Academy. A systematic review of the literature was performed using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) approach. Medline and Embase databases were utilized. The primary outcome measure was the rate of local control. A detailed review and interpretation of eligible studies is provided in the manuscript tables and text. Recommendations were defined as follows: (1) consensus: approved by >75% of experts; (2) predominant: approved by >50% of experts; (3) controversial: not approved by a majority of experts. Expert consensus supports dose escalation as critical in optimizing local control following radiation therapy for chordoma. In addition, comprehensive target volumes including sites of potential microscopic involvement improve local control compared with focal targets. Level I and high-quality multi-institutional data comparing treatment modalities, sequencing of radiation and surgery, and dose/fractionation schedules are needed to optimize patient outcomes in this locally aggressive malignancy.

Neurotrauma in Indigenous Populations of Canada-Challenges and Opportunities at a Global Level: A Scoping Review

BACKGROUND

Neurotrauma accounts for over 24,000 hospitalizations annually in Canada and has a significant impact in many developed countries. Among those affected, indigenous peoples are disproportionately impacted. The present scoping review explores the factors contributing to neurotrauma in indigenous populations and potential strategies to address this health care issue at a global level.

METHODS

A search was performed in Medline (1974-2021) and Embase (1946-2021) to identify studies pertaining to neurotrauma in indigenous populations of Canada. Search terms included 'Aboriginal', 'First Nation', 'Indigenous', 'traumatic brain injury', and 'traumatic spine injury'. Thematic analysis was then used to synthesize the information collected. A gray literature search was also performed.

RESULTS

The original literature search yielded 1609 articles, with 17 selected for the scoping review. Through thematic analysis, the factors contributing to neurotrauma burden in indigenous populations of Canada were summarized into 3 themes: inadequate resources available, social problems in indigenous communities, and challenges within the health care system. The potential strategies to address neurotrauma were also summarized into 3 themes: system-level changes to Canadian health care, community-based initiatives, and culturally appropriate solutions. The gray literature search revealed a lack of government reports on the topic and notable advocacy work from community organizations.

CONCLUSIONS

Systems-level interventions guided by indigenous community members will help to address the disparities that indigenous peoples face in the care and rehabilitation of neurotrauma. This study will inform further research of culturally appropriate approaches to reduce neurotrauma among indigenous peoples at a global level.

Single-cell analysis reveals clonally expanded tumor-associated CD57+ CD8 T cells are enriched in the periphery of patients with metastatic urothelial cancer responding to PD-L1 blockade

BACKGROUND

A growing body of evidence suggests that T-cell responses against neoantigens are critical regulators of response to immune checkpoint blockade. We previously showed that circulating neoantigen-specific CD8 T cells in patients with lung cancer responding to anti-Programmed death-ligand 1 (PD-L1) (atezolizumab) exhibit a unique phenotype with high expression of CD57, CD244, and KLRG1. Here, we extended our analysis on neoantigen-specific CD8 T cells to patients with metastatic urothelial cancer (mUC) and further profiled total CD8 T cells to identify blood-based predictive biomarkers of response to atezolizumab.

METHODS

We identified tumor neoantigens from 20 patients with mUC and profiled their peripheral CD8 T cells using highly multiplexed combinatorial tetramer staining. Another set of patients with mUC treated with atezolizumab (n=30) or chemotherapy (n=40) were selected to profile peripheral CD8 T cells by mass cytometry. Using single-cell transcriptional analysis (single-cell RNA sequencing (scRNA-seq)), together with CITE-seq (cellular indexing of transcriptomes and epitopes by sequencing) and paired T-cell receptor (TCR) sequencing, we further characterized peripheral CD8 T cells in a subset of patients (n=16).

RESULTS

High frequency of CD57 was observed in neoantigen-specific CD8 T cells in patients with mUC responding to atezolizumab. Extending these findings to bulk CD8 T cells, we found higher frequency of CD57 expressing CD8 T cells before treatment in patients responding to atezolizumab (n=20, p<0.01) but not to chemotherapy. These findings were corroborated in a validation cohort (n=30, p<0.01) and notably were independent of known biomarkers of response. scRNA-seq analysis identified a clonally expanded cluster enriched within CD57⁺ CD8 T cells in responding patients characterized by higher expression of genes associated with activation, cytotoxicity, and tissue-resident memory markers. Furthermore, compared with CD57^- CD8 T cells, TCRs of CD57⁺ CD8 T cells showed increased overlap with the TCR repertoire of tumor-infiltrating T cells.

CONCLUSIONS

Collectively, we show high frequencies of CD57 among neoantigen-specific and bulk CD8 T cells in patients responding to atezolizumab. The TCR repertoire overlap between peripheral CD57⁺ CD8 T cells and tumor-infiltrating lymphocytes suggest that accumulation of peripheral CD57⁺ CD8 T cells is reflective of an ongoing antitumor T-cell response. Our findings provide evidence and rationale for using circulating CD8 T cells expressing CD57 as a readily accessible blood-based biomarker for selecting patients with mUC for atezolizumab therapy.

Abstract 6226: Single-cell analysis reveals clonally expanded CD57+ CD8 T cells in periphery are associated with response to PD-L1 blockade in bladder cancer patients

The recent success of immune checkpoint blockade has revolutionized cancer treatment for many cancers, however, only a fraction of patients with advanced stages of cancers experience clinical benefit. Many studies have suggested that T cells against tumor neoantigens are critical mediators of response to checkpoint blockade. We showed previously that neoantigen-specific CD8 T cells in cancer patients responding to anti-PD-L1 (atezolizumab) therapy express high levels of CD57 and KLRG1. Here, we extended the study to bladder cancer patients treated with atezolizumab to identify predictive biomarkers of response. We immune profiled circulating CD8 T cells using multidimensional mass cytometry and single cell sequencing, and compared patients with objective response and progressive disease.

We found a higher frequency of CD57-expressing CD8 T cells at baseline in responding patients compared to patients who progressed during therapy (n=20, p&lt;0.01). High expression of CD57 was also observed in neoantigen-specific CD8 T cells in responding patients. These findings were corroborated in a validation cohort (n=30, p&lt;0.01) and notably, higher frequency of CD57+ T cells was only observed in patients responding to atezolizumab and not in patients responding to chemotherapy treatment (n=40). We further used single-cell transcriptomics, together with CITE-seq and paired TCR sequencing, to characterize CD57+ CD8 T cells in a subset of patients (n=16) and identified a cluster within CD57+ CD8 T cells, which was characterized by enrichment of genes associated with activation, cytotoxicity and tissue resident memory markers in responding patients. Compared to patients with progressive disease, there was an increased clonal expansion among CD57+ CD8 T cells at baseline in responders, which was driven specifically by the activated cluster. Furthermore, we found increased overlap between TCR repertoires of tumor-infiltrating T cells and CD57+CD8 T cells, compared to CD57- CD8 T cells in the periphery, suggesting that levels of CD57+ CD8 T cells in the periphery could be indicative of quality of anti-tumor T cell response.This study identified and confirmed that elevated levels of circulating CD8 T cells expressing CD57 are associated with response to atezolizumab in bladder cancer patients. These data provide evidence and rationale for an easily accessible blood-based biomarker for selecting patients for atezolizumab therapy.

Citation Format: Mahesh Yadav, Michael Fehlings, Leesun Kim, Xiangnan Guan, Kobe C. Yuen, Alireza Tafazzol, Deepali Rishipathak, Shomyesh Sanjabi, Andrew Wallace, Alessandra Nardin, Siming Ma, Ana Milojkovic, Evan Newell, Sanjeev Mariathasan. Single-cell analysis reveals clonally expanded CD57+ CD8 T cells in periphery are associated with response to PD-L1 blockade in bladder cancer patients [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 6226.

NY-ESO-1-specific redirected T cells with endogenous TCR knockdown mediate tumor response and cytokine release syndrome

Background

Because of the shortage of ideal cell surface antigens, the development of T-cell receptor (TCR)-engineered T cells (TCR-T) that target intracellular antigens such as NY-ESO-1 is a promising approach for treating patients with solid tumors. However, endogenous TCRs in vector-transduced T cells have been suggested to impair cell-surface expression of transduced TCR while generating mispaired TCRs that can become self-reactive.

Methods

We conducted a first-in-human phase I clinical trial with the TCR-transduced T-cell product (TBI-1301) in patients with NY-ESO-1-expressing solid tumors. In manufacturing TCR-T cells, we used a novel affinity-enhanced NY-ESO-1-specific TCR that was transduced by a retroviral vector that enables siRNA (small interfering RNA)-mediated silencing of endogenous TCR. The patients were divided into two cohorts. Cohort 1 was given a dose of 5×10⁸ cells (whole cells including TCR-T cells) preconditioned with 1500 mg/m² cyclophosphamide. Cohort 2 was given 5× 10⁹ cells preconditioned with 1500 mg/m² cyclophosphamide.

Results

In vitro study showed that both the CD8⁺ and CD4⁺ T fractions of TCR-T cells exhibited cytotoxic effects against NY-ESO-1-expressing tumor cells. Three patients and six patients were allocated to cohort 1 and cohort 2, respectively. Three of the six patients who received 5×10⁹ cells showed tumor response, while three patients developed early-onset cytokine release syndrome (CRS). One of the patients developed a grade 3 lung injury associated with the infiltration of the TCR-T cells. No siRNA-related adverse events other than CRS were observed. Cytokines including interleukin 6 I and monocyte chemotactic protein-1/chemokine (C-C motif) ligand (CCL2)

increased in the sera of patients with CRS. In vitro analysis showed these cytokines were not secreted from the T cells infused. A significant fraction of the manufactured T cells in patients with CRS was found to express either CD244, CD39, or both at high levels.

Conclusions

The trial showed that endogenous TCR-silenced and affinity-enhanced NY-ESO-1 TCR-T cells were safely administered except for grade 3 lung injury. The TCR-T cell infusion exhibited significant tumor response and early-onset CRS in patients with tumors that express NY-ESO-1 at high levels. The differentiation properties of the manufactured T cells may be prognostic for TCR-T-related CRS.

Trial registration number

NCT02366546.

Minimal cross-over between mutations associated with Omicron variant of SARS-CoV-2 and CD8+ T cell epitopes identified in COVID-19 convalescent individuals

There is a growing concern that ongoing evolution of SARS-CoV-2 could lead to variants of concern (VOC) that are capable of avoiding some or all of the multi-faceted immune response generated by both prior infection or vaccination, with the recently described B.1.1.529 (Omicron) VOC being of particular interest. Peripheral blood mononuclear cell samples from PCR-confirmed, recovered COVID-19 convalescent patients (n=30) infected with SARS-CoV-2 in the United States collected in April and May 2020 who possessed at least one or more of six different HLA haplotypes were selected for examination of their anti-SARS-CoV-2 CD8+ T-cell responses using a multiplexed peptide-MHC tetramer staining approach. This analysis examined if the previously identified viral epitopes targeted by CD8+ T-cells in these individuals (n=52 distinct epitopes) are mutated in the newly described Omicron VOC (n=50 mutations). Within this population, only one low-prevalence epitope from the Spike protein restricted to two HLA alleles and found in 2/30 (7%) individuals contained a single amino acid change associated with the Omicron VOC. These data suggest that virtually all individuals with existing anti-SARS-CoV-2 CD8+ T-cell responses should recognize the Omicron VOC, and that SARS-CoV-2 has not evolved extensive T-cell escape mutations at this time.

IMPORTANCE

The newly identified Omicron variant of concern contains more mutations than any of the previous variants described to date. In addition, many of the mutations associated with the Omicron variant are found in areas that are likely bound by neutralizing antibodies, suggesting that the first line of immunological defense against COVID-19 may be compromised. However, both natural infection and vaccination develop T-cell based responses, in addition to antibodies. This study examined if the parts of the virus, or epitopes, targeted by the CD8+ T-cell response in thirty individuals who recovered from COVID-19 in 2020 were mutated in the Omicron variant. Only one of 52 epitopes identified in this population contained an amino acid that was mutated in Omicron. These data suggest that the T-cell immune response in previously infected, and most likely vaccinated individuals, should still be effective against Omicron.

CD8+ T-Cell Responses in COVID-19 Convalescent Individuals Target Conserved Epitopes From Multiple Prominent SARS-CoV-2 Circulating Variants

This study examined whether CD8+ T-cell responses from coronavirus disease 2019 convalescent individuals (n = 30) potentially maintain recognition of the major severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants (alpha, beta, gamma; n = 45 mutations assessed). Only 1 mutation found in Beta variant-spike overlapped with a previously identified epitope (1/52), suggesting that virtually all anti-SARS-CoV-2 CD8+ T-cell responses should recognize these newly described variants.

Tissue-resident-like CD4+ T cells secreting IL-17 control Mycobacterium tuberculosis in the human lung

T cell immunity is essential for the control of tuberculosis (TB), an important disease of the lung, and is generally studied in humans using peripheral blood cells. Mounting evidence, however, indicates that tissue-resident memory T cells (Trms) are superior at controlling many pathogens, including Mycobacterium tuberculosis (M. tuberculosis), and can be quite different from those in circulation. Using freshly resected lung tissue, from individuals with active or previous TB, we identified distinct CD4+ and CD8+ Trm-like clusters within TB-diseased lung tissue that were functional and enriched for IL-17-producing cells. M. tuberculosis-specific CD4+ T cells producing TNF-α, IL-2, and IL-17 were highly expanded in the lung compared with matched blood samples, in which IL-17+ cells were largely absent. Strikingly, the frequency of M. tuberculosis-specific lung T cells making IL-17, but not other cytokines, inversely correlated with the plasma IL-1β levels, suggesting a potential link with disease severity. Using a human granuloma model, we showed the addition of either exogenous IL-17 or IL-2 enhanced immune control of M. tuberculosis and was associated with increased NO production. Taken together, these data support an important role for M. tuberculosis-specific Trm-like, IL-17-producing cells in the immune control of M. tuberculosis in the human lung.

SARS-CoV-2-specific CD8+ T cell responses in convalescent COVID-19 individuals

Characterization of the T cell response in individuals who recover from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is critical to understanding its contribution to protective immunity. A multiplexed peptide-MHC tetramer approach was used to screen 408 SARS-CoV-2 candidate epitopes for CD8+ T cell recognition in a cross-sectional sample of 30 coronavirus disease 2019 convalescent individuals. T cells were evaluated using a 28-marker phenotypic panel, and findings were modelled against time from diagnosis and from humoral and inflammatory responses. There were 132 SARS-CoV-2-specific CD8+ T cell responses detected across 6 different HLAs, corresponding to 52 unique epitope reactivities. CD8+ T cell responses were detected in almost all convalescent individuals and were directed against several structural and nonstructural target epitopes from the entire SARS-CoV-2 proteome. A unique phenotype for SARS-CoV-2-specific T cells was observed that was distinct from other common virus-specific T cells detected in the same cross-sectional sample and characterized by early differentiation kinetics. Modelling demonstrated a coordinated and dynamic immune response characterized by a decrease in inflammation, increase in neutralizing antibody titer, and differentiation of a specific CD8+ T cell response. Overall, T cells exhibited distinct differentiation into stem cell and transitional memory states (subsets), which may be key to developing durable protection.

CD8+ T cell responses in COVID-19 convalescent individuals target conserved epitopes from multiple prominent SARS-CoV-2 circulating variants

This study examined whether CD8+ T-cell responses from COVID-19 convalescent individuals(n=30) potentially maintain recognition of the major SARS-CoV-2 variants. Out of 45 mutations assessed, only one from the B.1.351 Spike overlapped with a low-prevalence CD8+ epitope, suggesting that virtually all anti-SARS-CoV-2 CD8+ T-cell responses should recognize these newly described variants.

CD8+ T cell responses in convalescent COVID-19 individuals target epitopes from the entire SARS-CoV-2 proteome and show kinetics of early differentiation

Characterization of the T cell response in individuals who recover from SARS-CoV-2 infection is critical to understanding its contribution to protective immunity. A multiplexed peptide-MHC tetramer approach was used to screen 408 SARS-CoV-2 candidate epitopes for CD8+ T cell recognition in a cross-sectional sample of 30 COVID-19 convalescent individuals. T cells were evaluated using a 28-marker phenotypic panel, and findings were modelled against time from diagnosis, humoral and inflammatory responses. 132 distinct SARS-CoV-2-specific CD8+ T cell epitope responses across six different HLAs were detected, corresponding to 52 unique reactivities. T cell responses were directed against several structural and non-structural virus proteins. Modelling demonstrated a coordinated and dynamic immune response characterized by a decrease in inflammation, increase in neutralizing antibody titer, and differentiation of a specific CD8+ T cell response. Overall, T cells exhibited distinct differentiation into stem-cell and transitional memory states, subsets, which may be key to developing durable protection.

Unbiased Profiling Reveals Compartmentalization of Unconventional T-Cells Within the Intestinal Mucosa Irrespective of HIV Infection

The intestinal mucosa is enriched for unconventional T-cells, including mucosal associated invariant T-cells (MAIT), invariant natural killer T-cells (iNKT) and γδ T-cells. These cells are activated by bacterial metabolites, lipid antigens and cytokines, and are important for intestinal barrier integrity. The loss of gut homeostasis observed in HIV infection is central to disease pathogenesis, and studies have highlighted impairment of particular unconventional T-cell subsets within a specific gut compartment. However, although the small and large intestine are distinct niches, the overall impact of HIV on unconventional T-cells across the gut mucosal has not been well-studied. We hypothesized that compartment specific differences in the unconventional T-cell repertoire would exist between the small and large intestine, due to increasing bacterial loads and microbial diversity; and that the impact of HIV infection might differ depending on the compartment examined. We used mass cytometry, flow cytometry and unbiased T-cell receptor profiling to quantify unconventional T-cells in blood and tissue from the small (duodenum) and large (colon) intestine in HIV infected and uninfected participants undergoing examination for a range of intestinal conditions. Overall, we find distinct compartmentalisation of T-cells between blood, duodenum and colon, with iNKT cells significantly enriched in the duodenum and δ-1 expressing γδ T-cells in the colon. In addition, we observe greater clonal expansion of conventional TCRs in the duodenum, suggestive of stronger adaptive immunity in this compartment. Conversely, we find evidence of an expanded unconventional TCR repertoire in the colon, which contained far more overlapping “donor unrestricted” sequences than the duodenum. Twelve of these TCRs were highly “MAIT-like” and 3 were unique to the colon, suggesting an enrichment of donor unrestricted T-cells (DURTs) in this compartment. Unexpectedly, however, no significant impact of HIV infection on any of the unconventional T-cell subsets measured was observed in either mucosal site in terms of frequency or TCR repertoire. Further studies are required to investigate the importance of these unconventional T-cell subsets to intestinal homeostasis within the different gut compartments and determine if they are functionally impaired during HIV infection.

Ontogeny of different subsets of yellow fever virus-specific circulatory CXCR5+ CD4+ T cells after yellow fever vaccination

Monitoring the frequency of circulatory CXCR5⁺ (cCXCR5⁺) CD4⁺ T cells in periphery blood provides a potential biomarker to draw inferences about T follicular helper (T_FH) activity within germinal center. However, cCXCR5⁺ T cells are highly heterogeneous in their expression of ICOS, PD1 and CD38 and the relationship between different cCXCR5 subsets as delineated by these markers remains unclear. We applied class II tetramer reagents and mass cytometry to investigate the ontogeny of different subsets of cCXCR5⁺ T cell following yellow fever immunization. Through unsupervised analyses of mass cytometry data, we show yellow fever virus-specific cCXCR5 T cells elicited by vaccination were initially CD38⁺ICOS⁺PD1⁺, but then transitioned to become CD38⁺ICOS^-PD1⁺ and CD38^-ICOS^-PD1⁺ before coming to rest as a CD38^-ICOS^-PD1^- subset. These results imply that most antigen-specific cCXCR5⁺ T cells, including the CD38^-ICOS^-PD1^- CXCR5⁺ T cells are derived from the CXCR5⁺CD38⁺ICOS⁺PD1⁺ subset, the subset that most resembles preT_FH/T_FH in the germinal center.

Hepatocellular Carcinoma Cells Up-regulate PVRL1, Stabilizing PVR and Inhibiting the Cytotoxic T-Cell Response via TIGIT to Mediate Tumor Resistance to PD1 Inhibitors in Mice

BACKGROUND & AIMS

Immune checkpoint inhibitors are effective in the treatment of some hepatocellular carcinomas (HCCs), but these tumors do not always respond to inhibitors of programmed cell death 1 (PDCD1, also called PD1). We investigated mechanisms of resistance of liver tumors in mice to infiltrating T cells.

METHODS

Mice were given hydrodynamic tail vein injections of clustered regularly interspaced short palindromic repeats-Cas9 (CRISPR-Cas9) and transposon vectors to disrupt Trp53 and overexpress C-Myc (Trp53^KO/C-Myc^OE mice). Pvrl1 and Pvrl3 were knocked down in Hepa1-6 cells by using short hairpin RNAs. Hepa1-6 cells were injected into livers of C57BL/6 mice; some mice were given intraperitoneal injections of antibodies against PD1, T-cell immunoreceptor with Ig and ITIM domains (TIGIT), or CD8 before the cancer cells were injected. Liver tissues were collected from mice and analyzed by histology, immunohistochemistry, and quantitative real-time polymerase chain reaction; tumors were analyzed by mass cytometry using markers to detect T cells and other lymphocytes. We obtained HCC and nontumorous liver tissues and clinical data from patients who underwent surgery in Hong Kong and analyzed the tissues by immunohistochemistry.

RESULTS

Trp53^KO/C-Myc^OE mice developed liver tumors in 3-5 weeks; injections of anti-PD1 did not slow tumor development. Tumors from mice given anti-PD1 had larger numbers of memory CD8⁺ T cells (CD44⁺CD62L^-KLRG1^int) and T cells that expressed PD1, lymphocyte activating 3 (LAG3), and TIGIT compared with mice not given the antibody. HCC tissues from patients had higher levels of PVRL1 messenger RNA and protein than nontumorous tissues. Increased PVRL1 was associated with shorter times of disease-free survival. Knockdown of Pvrl1 in Hepa1-6 cells caused them to form smaller tumors in mice, infiltrated by higher numbers of CD8⁺ T cells that expressed the inhibitory protein TIGIT; these effects were not observed in mice with depletion of CD8⁺ T cells. In Hepa1-6 cells, PVRL1 stabilized cell surface PVR, which interacted with TIGIT on CD8⁺ T cells; knockdown of Pvrl1 reduced cell-surface levels of PVR but not levels of Pvr messenger RNA. In Trp53^KO/C-Myc^OE mice and mice with tumors grown from Hepa1-6 cells, injection of the combination of anti-PD1 and anti-TIGIT significantly reduced tumor growth, increased the ratio of cytotoxic to regulatory T cells in tumors, and prolonged survival.

CONCLUSIONS

PVRL1, which is up-regulated by HCC cells, stabilizes cell surface PVR, which interacts with TIGIT, an inhibitory molecule on CD8⁺ effector memory T cells. This suppresses the ant-tumor immune response. Inhibitors of PVRL1/TIGIT, along with anti-PD1 might be developed for treatment of HCC.

Perioperative Anticoagulation Management in Spine Surgery: Initial Findings From the AO Spine Anticoagulation Global Survey

STUDY DESIGN

Cross-sectional, international survey.

OBJECTIVES

This study addressed the global perspectives concerning perioperative use of pharmacologic thromboprophylaxis during spine surgery along with its risks and benefits.

METHODS

A questionnaire was designed and implemented by expert members in the AO Spine community. The survey was distributed to AO Spine's spine surgeon members (N = 3805). Data included surgeon demographic information, type and region of practice, anticoagulation principles, different patient scenarios, and comorbidities.

RESULTS

A total of 316 (8.3% response rate) spine surgeons completed the survey, representing 64 different countries. Completed surveys were primarily from Europe (31.7%), South/Latin America (19.9%), and Asia (18.4%). Surgeons tended to be 35 to 44 years old (42.1%), fellowship-trained (74.7%), and orthopedic surgeons (65.5%) from academic institutions (39.6%). Most surgeons (70.3%) used routine anticoagulation risk stratification, irrespective of geographic location. However, significant differences were seen between continents with anticoagulation initiation and cessation methodology. Specifically, the length of a procedure (P = .036) and patient body mass index (P = .008) were perceived differently when deciding to begin anticoagulation, while the importance of medical clearance (P < .001) and reference to literature (P = .035) differed during cessation. For specific techniques, most providers noted use of mobilization, low-molecular-weight heparin, and mechanical prophylaxis beginning on postoperative 0 to 1 days. Conversely, bridging regimens were bimodal in distribution, with providers electing anticoagulant initiation on postoperative 0 to 1 days or days 5-6.

CONCLUSION

This survey highlights the heterogeneity of spine care and accentuates geographical variations. Furthermore, it identifies the difficulty in providing consistent perioperative anticoagulation recommendations to patients, as there remains no widely accepted, definitive literature of evidence or guidelines.

High-Dimensional Characterization of the Systemic Immune Landscape Informs on Synergism Between Radiation Therapy and Immune Checkpoint Blockade

PURPOSE

Improved antitumor responses have been observed in patients after combination radiation therapy (RT) and immune checkpoint blockade (ICB). Whether these clinical responses are linked to the host systemic immune system has not been elucidated.

METHODS AND MATERIALS

In this single-institution prospective observational study, peripheral blood was longitudinally collected from 10 patients with metastatic disease who had responded to anti-PD-1/anti-PD-L1 ICB and received RT (8-50 Gy in 1-5 fractions) upon disease progression at the following timepoints: baseline (pre-RT), 1 to 2 weeks post-RT, and post-ICB (cycle 1) on reintroduction post-RT. To thoroughly characterize the interaction between combined RT-ICB and the host immune system, we performed high-dimensional, mass cytometry-based immunophenotyping of circulating lymphocytes using a 40-marker panel addressing lineage, differentiation, activation, trafficking, cytotoxicity, and costimulatory and inhibitory functions. Phenotypic expression of circulating lymphocytes was compared across patients and time points and correlated with post-RT tumor responses.

RESULTS

Foremost, we demonstrated excellent posttreatment clinical responses, including 4 local responses with >50% reduction in radiated tumor size, 1 out-of-field response, and 4 patients who resumed ICB for >1 year. Baseline and post-RT immune states were highly heterogeneous among patients. Despite this interindividual heterogeneity in baseline immune states, we observed a systemic immune reaction to RT-ICB common across patients, histology, and radiation sites; a subset of pre-existing Ki-67+ CD8+ T cells were increased post-RT and further expanded upon reintroduction of ICB post-RT (2.3-fold increase, P = .02). Importantly, RT did not alter the phenotypic profile of these Ki-67+ CD8+ T cells, which was characterized by a distinct activated and differentiated effector phenotype.

CONCLUSIONS

Collectively, these findings point toward a sustained reinvigoration of host antitumor immunity after RT-ICB and suggest an expansion in activated Ki-67+ CD8+ T cells as a possible demonstration of this synergy, thereby providing new insights that may support the development of optimal sequencing strategies.

targetSCAPE and ultraSCAPE: Simultaneous identification and deep profiling of human antigen-specific T cells and other immune cell subsets by mass cytometry

e15204

Background: During clinical trial immune monitoring, especially in the field of immunotherapy, it is critical to collect in-depth phenotypic information from multiple immune cell populations in order to assess the biological activity of the immunotherapy, to identify biomarkers of response or disease progression, and/or to identify new drug targets. However, patient samples such as peripheral blood mononuclear cells or tissues, are often scarce and current methods face limitations in either achieving a sufficient depth of analysis and/or cell throughput. Methods: In order to identify therapy-relevant antigens and to facilitate a concurrent in-depth characterization of T cells directed towards these targets, immunoSCAPE leverages the high-dimensional immune profiling capabilities of mass cytometry and a unique methodology allowing the identification and characterization of rare antigen-specific T-cell subsets (targetSCAPE). By implementing a new cutting-edge technology that combines flow and mass cytometry in parallel with a combinatorial live cell barcoding strategy, we further increased the high-dimensional phenotyping capacities to over 100 different marker molecules on up to four different immune cell subsets simultaneously within the same sample. Results: We isolated 4 different immune cell populations from a single sample and combined 3 different phenotypic panels consisting of 35 makers each together with a combinatorial tetramer multiplex and phenotyping panel for deep profiling of myeloid cells, NK cells, B cells and T cells. We demonstrate the potential of this novel immuno-phenotyping method, by tracking virus-specific T cells while simultaneously characterizing 4 immune cell subsets with over 100 distinct phenotypic markers from a single sample, which is currently impossible employing modern flow cytometers or classical mass cytometry methods. Conclusions: With its ability to provide an unprecedented picture of the immune status within a single sample, including T cell specificity information and in-depth profiling of relevant immune cell subsets, ultraSCAPE in combination with targetSCAPE can provide detailed insights on the effects of immunotherapy on the immune cell population. Information learned from in-depth immune phenotyping of several immune cell subsets such as T, B, NK and myeloid cell subsets can be leveraged for the development of novel diagnostics, biomarker discovery and monitoring therapeutic strategies in immunotherapy clinical trials.

Immuno-phenotyping of tumor-specific CD8 T cells using high-dimensional mass cytometry

There is strong evidence that tumor-specific T cells play a central role in tumor rejection. immunoSCAPE leverages the high-dimensional immune profiling capabilities of CyTOF for the identification of antigen-specific T cells to support the development of immunotherapy strategies. By applying CyTOF in conjunction with combinatorial peptide-MHC tetramer staining and high-performance dimensional analysis tools, we broadly and sensitively map T cell reactivity against MHC-class I epitopes while concurrently performing in-depth characterization of these rare antigen-specific T cells.

Here, we have applied our unique capabilities to detect and characterize circulating neoantigen-specific T cells in lung carcinoma patient undergoing atezolizumab treatment. Out of 782 neoantigen candidates, T cell reactivity against 13 unique neoantigens was detected within patients who responded to atezolizumab treatment, while T cells within non-responder patients recognized 7 neoantigens. Additionally, neoantigen-specific CD8 T cells from treatment responders exhibit a differentiated effector phenotype similar to CMV or EBV-specific T cells, whereas neoantigen-specific CD8 T cells from non-responders display a memory-like phenotype, suggesting that the properties of tumor-reactive T cells may be associated with clinical response to anti-PD-L1 treatment.

By providing insight into the nature and function of tumor-specific T cells, immunoSCAPE’s unique high-dimensional immune profiling platform is a valuable tool to guide the development of novel immunotherapy strategies through assessment of drug biological activity, definition of mechanism of action, and identification of biomarkers of patient response.

Novel innovations in cell and gene therapies for spinal cord injury

Spinal cord injury (SCI) leads to chronic and multifaceted disability, which severely impacts the physical and mental health as well as the socio-economic status of affected individuals. Permanent disabilities following SCI result from the failure of injured neurons to regenerate and rebuild functional connections with their original targets. Inhibitory factors present in the SCI microenvironment and the poor intrinsic regenerative capacity of adult spinal cord neurons are obstacles for regeneration and functional recovery. Considerable progress has been made in recent years in developing cell and molecular approaches to enable the regeneration of damaged spinal cord tissue. In this review, we highlight several potent cell-based approaches and genetic manipulation strategies (gene therapy) that are being investigated to reconstruct damaged or lost spinal neural circuits and explore emerging novel combinatorial approaches for enhancing recovery from SCI.

Abstract A8: Immuno-phenotyping of tumor-specific CD8 T cells using high-dimensional mass cytometry

There is strong evidence that tumor-specific T cells play a central role in tumor rejection. However, few tools can simultaneously detect rare antigen-specific T cells and deeply characterize their function and phenotype. immunoSCAPE leverages the high-dimensional immune profiling capabilities of mass cytometry combined with a unique technology for the identification of antigen-specific T cells to support the development of immunotherapy strategies. By applying cytometry by time of flight in conjunction with combinatorial peptide-MHC tetramer staining and high-performance dimensional analysis tools, we broadly and sensitively map T-cell reactivity against MHC-class I epitopes while concurrently performing in-depth characterization of these rare antigen-specific T cells. Here, we have applied our unique capabilities to detect and characterize circulating neoantigen-specific T cells in lung carcinoma patients undergoing atezolizumab treatment. Out of 782 neoantigen candidates, T-cell reactivity against 13 unique neoantigens was detected within patients who responded to atezolizumab treatment, while T cells within nonresponder patients recognized 7 neoantigens. Additionally, neoantigen-specific CD8 T cells from treatment responders exhibit a differentiated effector phenotype similar to CMV or EBV-specific T cells, whereas neoantigen-specific CD8 T cells from nonresponders display a memory-like phenotype, suggesting that the properties of tumor-reactive T cells may be associated with clinical response to anti-PD-L1 treatment. By providing insight into the nature and function of tumor-specific T cells, immunoSCAPE’s unique high-dimensional immune profiling platform is a valuable tool to guide the development of novel immunotherapy strategies through assessment of drug biologic activity, definition of mechanism of action, and identification of biomarkers of patient response.

Citation Format: David Roumanes, Michael Fehlings, Mahesh Yadav, Alessandra Nardin. Immuno-phenotyping of tumor-specific CD8 T cells using high-dimensional mass cytometry [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 A8.

The graded redefined assessment of strength sensibility and prehension version 2 (GV2): Psychometric properties

Context: GRASSP Version 1 (GV1) was developed in 2010, is an upper extremity measure specifically designed to assess recovery after traumatic tetraplegia. A second version was developed to reduce length of the test and refine instructions/standardization. The purpose of this post hoc analysis was to calculate psychometric properties of GRASSP Version 2 (GV2). Design/Setting: A post-hoc analysis of datasets for the GRASSP cross-sectional (n = 72 chronic,) and longitudinal (n = 127 acute) studies was conducted. Reliability, validity and MDD were calculated from the chronic sample and responsiveness was re-calculated from the longitudinal sample. Both studies were observational. Participants: A chronic sample (n = 72) and acute longitudinal sample (n = 127) of individuals with traumatic tetraplegia (AIS A to D, NLI C2 to C8) were studied. Outcome Measures: GV1, the Spinal Cord Independence Measure III (SCIM), International Standards of Neurological Classification of Spinal Cord Injury (ISNCSCI) were administered in both studies at all centers and the Capabilities of the Upper Extremity Questionnaire (CUE-Q) was administered in North American sites only. GRASSP-Palmar Sensation, GRASSP-Prehension Performance subtest items included in GV2 were re-analyzed for reliability; validity, MDD and responsiveness. Results: Inter-rater and test-retest reliability for all subtests ranged between 0.849-0.971 and 0.950-0.971 respectively. Concurrent validity between domains of GV2 were positively and moderately (0.530-0.830, P < 0.0001) correlated to SCIM, SCIM self-care subscore (SS) and CUE-Q. MDD values were 4 and 3 points for sensation and prehension performance (single side). Responsiveness values were .84-.88 for GR-Sens and .93-1.22 for GR-PP respectively. Conclusions: GV2 retains excellent psychometric properties as does GV1.

Late-differentiated effector neoantigen-specific CD8+ T cells are enriched in peripheral blood of non-small cell lung carcinoma patients responding to atezolizumab treatment

BACKGROUND

There is strong evidence that immunotherapy-mediated tumor rejection can be driven by tumor-specific CD8+ T cells reinvigorated to recognize neoantigens derived from tumor somatic mutations. Thus, the frequencies or characteristics of tumor-reactive, mutation-specific CD8+ T cells could be used as biomarkers of an anti-tumor response. However, such neoantigen-specific T cells are difficult to reliably identify due to their low frequency in peripheral blood and wide range of potential epitope specificities.

METHODS

Peripheral blood mononuclear cells (PBMC) from 14 non-small cell lung cancer (NSCLC) patients were collected pre- and post-treatment with the anti-PD-L1 antibody atezolizumab. Using whole exome sequencing and RNA sequencing we identified tumor neoantigens that are predicted to bind to major histocompatibility complex class I (MHC-I) and utilized mass cytometry, together with cellular 'barcoding', to profile immune cells from patients with objective response to therapy (n = 8) and those with progressive disease (n = 6). In parallel, a highly-multiplexed combinatorial tetramer staining was used to screen antigen-specific CD8+ T cells in peripheral blood for 782 candidate tumor neoantigens and 71 known viral-derived control peptide epitopes across all patient samples.

RESULTS

No significant treatment- or response associated phenotypic difference were measured in bulk CD8+ T cells. Multiplexed peptide-MHC multimer staining detected 20 different neoantigen-specific T cell populations, as well as T cells specific for viral control antigens. Not only were neoantigen-specific T cells more frequently detected in responding patients, their phenotypes were also almost entirely distinct. Neoantigen-specific T cells from responder patients typically showed a differentiated effector phenotype, most like Cytomegalovirus (CMV) and some types of Epstein-Barr virus (EBV)-specific CD8+ T cells. In contrast, more memory-like phenotypic profiles were observed for neoantigen-specific CD8+ T cells from patients with progressive disease.

CONCLUSION

This study demonstrates that neoantigen-specific T cells can be detected in peripheral blood in non-small cell lung cancer (NSCLC) patients during anti-PD-L1 therapy. Patients with an objective response had an enrichment of neoantigen-reactive T cells and these cells showed a phenotype that differed from patients without a response. These findings suggest the ex vivo identification, characterization, and longitudinal follow-up of rare tumor-specific differentiated effector neoantigen-specific T cells may be useful in predicting response to checkpoint blockade.

TRIAL REGISTRATION

POPLAR trial NCT01903993 .

[Not Available]

Objectif

Sensibiliser les médecins de famille à la myélopathie cervicale dégénérative (MCD) afin de les aider à dépister, à diagnostiquer et à traiter la maladie de façon plus efficace.

Sources de l’information

Une recherche d’articles publiés entre 1970 et octobre 2017 a été effectuée sur PubMed à l’aide des mots-clés anglais cervical myelopathy et degenerative spinal cord injury avec family medicine ou primary care.

Message principal

Le diagnostic de MCD reste souvent omis ou retardé en première ligne en raison du peu de connaissances sur la maladie, de même que de la grande variabilité de ses manifestations. L’évolution naturelle de la MCD accuse un déclin par paliers, les symptômes allant d’une faiblesse musculaire à la paralysie complète. Toutes les personnes qui présentent des signes et des symptômes doivent être recommandées en chirurgie de la colonne vertébrale aux fins d’évaluation; les personnes dont le cas est léger peuvent recevoir un traitement prudent, mais doivent quand même recevoir une évaluation et une opinion chirurgicales. Les patients asymptomatiques qui présentent des signes de compression de la moelle épinière à l’imagerie par résonance magnétique devraient être recommandés aux fins d’évaluation; mais la chirurgie leur est déconseillée. Il est essentiel de surveiller de près les personnes asymptomatiques ou celles atteintes d’un cas léger de MCD afin de détecter toute détérioration neurologique.

Conclusion

La myélopathie cervicale dégénérative est la cause la plus fréquente de dysfonctionnement de la moelle épinière chez les adultes. Cette révision aide à clarifier le diagnostic en première ligne, ce qui améliore les chances de poser un diagnostic précoce et de prévenir tout déclin neurologique supplémentaire chez les patients.

Degenerative cervical myelopathy: Diagnosis and management in primary care

OBJECTIVE

To raise awareness about degenerative cervical myelopathy (DCM) and to help family physicians identify, diagnose, and manage DCM more effectively.

SOURCES OF INFORMATION

A PubMed search was conducted for articles published between 1970 and October 2017, using the terms cervical myelopathy and degenerative spinal cord injury with family medicine or primary care.

MAIN MESSAGE

Owing to limited knowledge of DCM in primary care, along with the large variability of the disease, the diagnosis of DCM is often missed or delayed. The natural course of DCM presents as a stepwise decline, with symptoms ranging from muscle weakness to complete paralysis. All individuals with signs and symptoms should be referred to a spine surgeon for consideration of surgery; those with mild DCM might be offered conservative treatment but should receive a surgical evaluation and opinion nonetheless. Asymptomatic patients with evidence of cord compression on magnetic resonance imaging might need to be referred for assessment; however, surgery is not advised. It is critical to closely monitor asymptomatic individuals or those with mild DCM for neurologic deterioration.

CONCLUSION

Degenerative cervical myelopathy is the most common cause of spinal cord dysfunction in adults. This review helps streamline its diagnosis in primary care, allowing for improved chances of early diagnosis and prevention of further neurologic decline among patients.

Abstract 527: High-dimensional profiling of the systemic immune response informs on optimal sequencing of radiotherapy (RT) and immune checkpoint blockade (ICB)

Background: Combinatorial RT-ICB potentiates anti-tumour reactivity by modulating the immune response. We therefore performed in-depth phenotypic profiling of the systemic T cell compartment following treatment with RT-ICB.

Methods: We recruited 20 patients with biopsy-proven metastatic renal cell and non-small cell lung carcinoma, who were treated with a sandwich regime of ICB-RT-ICB under a prospective observational study protocol, and compared against a RT alone-treated cohort (N=10). All patients received ablative RT (8-50Gy/1-5fr) for oligoprogression and/ or local palliation. Blood samples were longitudinally collected at pre-RT, 14 d post-RT and cycle 2 ICB post-RT. Deep T cell profiling was performed by mass cytometry using a customised 41 parameter panel, together with high dimensional analysis tools.

Results: Median follow-up of the overall cohort was 18mo; median duration of ICB received in the ICB-RT-ICB arm was 15mo. We observed significant diversity of the systemic T cell repertoire between patients at baseline, and this corresponded to significant interpatient heterogeneity in T cell responses specific to the central/ effector memory, EMRA and Treg subsets post-RT. Dramatic local response (complete response at 1 mo post-RT) was significantly higher in the ICB-RT-ICB cohort compared to the RT alone cohort (12/20 vs 1/10, P&lt;0.01). This clinical phenomenon corresponded to an increased %Ki67high CD8 and CD4 T cells post-RT exclusively in the combinatorial treated cohort, which was further enhanced upon resumption of ICB (mean = 10% vs 3% [CD8]; 13% vs 2% [CD4]; P&lt;0.01). Deeper immunophenotyping of the Ki67high subsets revealed associated high expression of GranzymeB and Eomes.

Conclusions: Here, we observed changes in the T cell phenotypes that varied remarkably across all patients following RT. We further highlight a RT-dependent T cell proliferation amongst all RT-ICB-treated patients that was further enhanced by ICB in prior responders. This immune phenomenon may account for the dramatic responses to combinatorial treatment, and informs on optimal sequencing strategies for combining RT and ICB.

Citation Format: Kevin L. Chua, Michael Fehlings, Pek Lim Chu, Xiao-Tian Lin, Eugenia Yeo, Kar Perng Low, Dennis Poon, Enya Ong, Wai Yee Woo, Joseph Wee, Alessandra Nardin, Gopalakrishna Iyer, Daniel S. Tan, Kee Chee Soo, Evan Newell, Melvin Chua. High-dimensional profiling of the systemic immune response informs on optimal sequencing of radiotherapy (RT) and immune checkpoint blockade (ICB) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 527.

Abstract 4055: Late-differentiated effector neoantigen-specific CD8+ T cells are enriched in non-small cell lung cancer patients responding to atezolizumab treatment

There is strong evidence that immunotherapy-mediated tumor rejection can be driven by the reinvigoration of tumor-specific CD8+ T cells recognizing neoantigens derived from tumor somatic mutations (citations). Thus, it is possible that the relative abundance and/or characteristics of these tumor-reactive, mutation-specific CD8+ T cells can be used as predictive biomarkers of response to immunotherapy. However, only a fraction of these potential neoantigens are usually immunogenic and in addition, these tumor-reactive, mutation-specific CD8+ cells are present only at low frequencies in blood, making it difficult to reliably identify these effector cells.

Here, mass cytometry and highly-multiplexed combinatorial tetramer staining together with cellular barcoding was used to profile immune cells in longitudinally collected PBMCs from 14

non-small cell lung cancer (NSCLC) patients treated with anti-PD-L1 (atezolizumab) antibody to compare patients with objective response (n=8) and progressive disease (n=6). Although no significant phenotypic differences were detected in bulk CD8+ T cells, greater insight was gained from a parallel analysis using highly multiplexed peptide-MHC multimer staining to screen and profile antigen-specific T cells.

A longitudinal analysis was performed using peripheral blood CD8+ T cells for 800 candidate tumor neoantigens and 73 known viral-derived control peptides across all patient samples. In addition to virus antigen-specific T cells, a total of 20 different neoantigen-specific T cell populations were detected and their high dimensional profiles were compared. We found that neoantigen-specific T cells were more frequently detected in responding patients and their phenotypes were almost entirely distinct from non-responding patients. Neoantigen-specific T cells from responding patients showed a differentiated effector phenotype with high expression of KLRG1, 2B4 (CD244) and CD57, similar to CD8+ T cells associated with CMV and some types of EBV infection. In contrast, more memory-like phenotypic profiles, with high CD27 and CD127 expression, were observed for neoantigen-specific CD8+ T cells from patients with progressive disease.

In addition to the utility of this approach for the ex vivo identification, characterization, and longitudinal tracking of rare tumor-specific T cells, this study supports further research into assessing whether the presence of late-differentiated neoantigen-specific T cells could be used as a predictor of response to checkpoint blockade.

Citation Format: Mahesh Yadav, Michael Fehlings, Suchit Jhunjhunwala, Bill O'Gorman, Priti Hegde, Leesun Kim, Alessandra Nardin, Susan Flynn, Hermi Sumatoh, Marcus Ballinger, David Shames, Boon Heng Lee, Evan Newell. Late-differentiated effector neoantigen-specific CD8+ T cells are enriched in non-small cell lung cancer patients responding to atezolizumab treatment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4055.

Immune profiling of tumor-infiltrating T cells using mass cytometry

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Background: Immunotherapy recent successes have opened new avenues for the treatment of cancer and the presence of tumor-specific CD8+ T cells in tumor-bearing individuals offer a promising therapeutic target. However, the detection and profiling of such T cells are challenging due to the need to detect rare antigen-specific T cell subpopulations in patient samples that are limited in size thus making it difficult to exploit these parameters for predictive signatures of clinical response. Moreover, the identification and analysis of neoantigen-specific CD8+ T-cells in tumor-bearing individuals is challenging due to the small pool of such cells. Methods: In order to identify therapy-relevant tumor antigens and to facilitate a concurrent in-depth characterization of cells directed towards these targets, immunoSCAPE leverages the high-dimensional immune profiling capabilities of cytometry by time of flight (CyTOF) combined with a unique technology allowing the identification rare antigen-specific T-cell subsets. Results: We applied this technology to patient tumor-infiltrating lymphocytes from human cancer samples and tumor-derived neoantigens recognized by T-cells were identified and characterized. Interestingly, the majority of patient-derived tumor infiltrates consisted of tumor-unrelated T-cells characterized by a diverse phenotype. Strikingly, the expression of CD39 was absent from these bystander cells, suggesting that CD39 could be a useful biomarker for the identification of putative tumor-reactive T cells. Conclusions: Simultaneous immune profiling revealed that tumor-unrelated, bystander CD8+ T-cells are phenotypically different in human tumor infiltrates and identified CD39 as a putative marker of neoantigen-specific T-cells. By providing insights into the nature, frequency and phenotype of antigen-specific T-cells, immunoSCAPE’s unique target discovery and high-dimensional immune profiling platform is a valuable tool for the development of novel diagnostic and therapeutic strategies in immunotherapy.

A Subset of Type I Conventional Dendritic Cells Controls Cutaneous Bacterial Infections through VEGFα-Mediated Recruitment of Neutrophils

Skin conventional dendritic cells (cDCs) exist as two distinct subsets, cDC1s and cDC2s, which maintain the balance of immunity to pathogens and tolerance to self and microbiota. Here, we examined the roles of dermal cDC1s and cDC2s during bacterial infection, notably Propionibacterium acnes (P. acnes). cDC1s, but not cDC2s, regulated the magnitude of the immune response to P. acnes in the murine dermis by controlling neutrophil recruitment to the inflamed site and survival and function therein. Single-cell mRNA sequencing revealed that this regulation relied on secretion of the cytokine vascular endothelial growth factor α (VEGF-α) by a minor subset of activated EpCAM+CD59+Ly-6D+ cDC1s. Neutrophil recruitment by dermal cDC1s was also observed during S. aureus, bacillus Calmette-Guérin (BCG), or E. coli infection, as well as in a model of bacterial insult in human skin. Thus, skin cDC1s are essential regulators of the innate response in cutaneous immunity and have roles beyond classical antigen presentation.

The role of high-dimensional profiling of the systemic immune response on optimal sequencing of radiotherapy (RT) and immune checkpoint blockade (ICB)

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Background: Combinatorial RT-ICB potentiates anti-tumour reactivity by modulating the immune response. We therefore performed in-depth phenotypic profiling of the systemic T cell compartment following treatment with RT-ICB. Methods: We recruited 20 patients with biopsy-proven metastatic renal cell and non-small cell lung carcinoma, who were treated with a sandwich regime of ICB-RT-ICB under a prospective observational study protocol, and compared against a RT alone-treated cohort (N = 10). All patients received ablative RT (8-50 Gy/1-5 fr) for oligoprogression and/or local palliation. Blood samples were longitudinally collected at pre-RT, 14 d post-RT and cycle 2 ICB post-RT. Deep T cell profiling was performed by mass cytometry using a customised 41 parameter panel, together with high dimensional analysis tools. Results: Median follow-up of the overall cohort was 18 mo; median duration of ICB received in the ICB-RT-ICB arm was 15 mo. We observed significant diversity of the systemic T cell repertoire between patients at baseline, and this corresponded to significant interpatient heterogeneity in T cell responses specific to the central/effector memory, EMRA and Treg subsets post-RT. Dramatic local response (complete response at 1 mo post-RT) was significantly higher in the ICB-RT-ICB cohort compared to the RT alone cohort (12/20 vs 1/10, P <0.01). This clinical phenomenon corresponded to an increased % Ki67highCD8 and CD4 T cells post-RT exclusively in the combinatorial treated cohort, which was further enhanced upon resumption of ICB (mean = 10% vs 3% [CD8]; 13% vs 2% [CD4]; P <0.01). Deeper immunophenotyping of the Ki67high subsets revealed associated high expression of GranzymeB and Eomes. Conclusions: Here, we observed changes in the T cell phenotypes that varied remarkably across all patients following RT. We further highlight a RT-dependent T cell proliferation amongst all RT-ICB-treated patients that was further enhanced by ICB in prior responders. This immune phenomenon may account for the dramatic responses to combinatorial treatment, and informs on optimal sequencing strategies for combining RT and ICB.

Multiplex MHC Class I Tetramer Combined with Intranuclear Staining by Mass Cytometry

Antigen-specific CD8⁺ T cells play a crucial role in the host protective immune response against viruses, tumors, and other diseases. Major histocompatibility complex (MHC) class I tetramers allow for a direct detection of such antigen-specific CD8⁺ T cells. Using mass cytometry together with multiplex MHC class I tetramer staining, we are able to screen more than 1000 different antigen candidates simultaneously across tissues in health and disease, while retaining the possibility to deliver an in-depth characterization of antigen-specific CD8⁺ T cells and associated phenotypes. Here we describe the method for a MHC class I tetramer multiplexing approach together with intracellular antibody staining for a parallel phenotypic cell characterization using mass cytometry in human specimens.

High-Dimensional Analysis Delineates Myeloid and Lymphoid Compartment Remodeling during Successful Immune-Checkpoint Cancer Therapy

Although current immune-checkpoint therapy (ICT) mainly targets lymphoid cells, it is associated with a broader remodeling of the tumor micro-environment. Here, using complementary forms of high-dimensional profiling, we define differences across all hematopoietic cells from syngeneic mouse tumors during unrestrained tumor growth or effective ICT. Unbiased assessment of gene expression of tumor-infiltrating cells by single-cell RNA sequencing (scRNAseq) and longitudinal assessment of cellular protein expression by mass cytometry (CyTOF) revealed significant remodeling of both the lymphoid and myeloid intratumoral compartments. Surprisingly, we observed multiple subpopulations of monocytes/macrophages, distinguishable by the markers CD206, CX3CR1, CD1d, and iNOS, that change over time during ICT in a manner partially dependent on IFNγ. Our data support the hypothesis that this macrophage polarization/activation results from effects on circulatory monocytes and early macrophages entering tumors, rather than on pre-polarized mature intratumoral macrophages.

Mass cytometry: a powerful tool for dissecting the immune landscape

Advancement in methodologies for single cell analysis has historically been a major driver of progress in immunology. Currently, high dimensional flow cytometry, mass cytometry and various forms of single cell sequencing-based analysis methods are being widely adopted to expose the staggering heterogeneity of immune cells in many contexts. Here, we focus on mass cytometry, a form of flow cytometry that allows for simultaneous interrogation of more than 40 different marker molecules, including cytokines and transcription factors, without the need for spectral compensation. We argue that mass cytometry occupies an important niche within the landscape of single-cell analysis platforms that enables the efficient and in-depth study of diverse immune cell subsets with an ability to zoom-in on myeloid and lymphoid compartments in various tissues in health and disease. We further discuss the unique features of mass cytometry that are favorable for combining multiplex peptide-MHC multimer technology and phenotypic characterization of antigen specific T cells. By referring to recent studies revealing the complexities of tumor immune infiltrates, we highlight the particular importance of this technology for studying cancer in the context of cancer immunotherapy. Finally, we provide thoughts on current technical limitations and how we imagine these being overcome.