SARS-CoV-2-Specific Memory T Lymphocytes From COVID-19 Convalescent Donors: Identification, Biobanking, and Large-Scale Production for Adoptive Cell Therapy

Effective virus-specific T-cell therapy for high-risk SARS-CoV-2 infections in hematopoietic stem cell transplant recipients: initial case studies and literature review

The COVID-19 pandemic has exacerbated mortality rates among immunocompromised patients, accentuating the need for novel, targeted therapies. Transplant recipients, with their inherent immune vulnerabilities, represent a subgroup at significantly heightened risk. Current conventional therapies often demonstrate limited effectiveness in these patients, calling for innovative treatment approaches. In immunocompromised transplant recipients, several viral infections have been successfully treated by adoptive transfer of virus-specific T-cells (VST). This paper details the successful application of SARS-CoV-2-specific memory T-cell therapy, produced by an interferon-γ cytokine capture system (CliniMACS® Prodigy device), in three stem cell transplant recipients diagnosed with COVID-19 (case 1: alpha variant, cases 2 and 3: delta variants). These patients exhibited persistent SARS-CoV-2 PCR positivity accompanied by bilateral pulmonary infiltrates and demonstrated only partial response to standard treatments. Remarkably, all three patients recovered and achieved viral clearance within 3 to 9 weeks post-VST treatment. Laboratory follow-up investigations identified an increase in SARS-CoV-2-specific T-cells in two of the cases. A robust anti-SARS-CoV-2 S (S1/S2) IgG serological response was also recorded, albeit with varying titers. The induction of memory T-cells within the CD4 + compartment was confirmed, and previously elevated interleukin-6 (IL-6) and IL-8 levels normalized post-VST therapy. The treatment was well tolerated with no observed adverse effects. While the need for specialized equipment and costs associated with VST therapy present potential challenges, the limited treatment options currently available for COVID-19 within the allogeneic stem cell transplant population, combined with the risk posed by emerging SARS-CoV-2 mutations, underscore the potential of VST therapy in future clinical practice. This therapeutic approach may be particularly beneficial for elderly patients with multiple comorbidities and weakened immune systems.

Results of phase 2 randomized multi-center study to evaluate the safety and efficacy of infusion of memory T cells as adoptive therapy in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia and/or lymphopenia (RELEASE NCT04578210)

BACKGROUND AIMS

There are currently no effective anti-viral treatments for coronavirus disease 2019 (COVID-19)-hospitalized patients with hypoxemia. Lymphopenia is a biomarker of disease severity usually present in patients who are hospitalized. Approaches to increasing lymphocytes exerting an anti-viral effect must be considered to treat these patients. Following our phase 1 study, we performed a phase 2 randomized multicenter clinical trial in which we evaluated the efficacy of the infusion of allogeneic off-the-shelf CD45RA- memory T cells containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells from convalescent donors plus the standard of care (SoC) versus just the SoC treatment.

METHODS

Eighty-four patients were enrolled in three Spanish centers. The patients were randomized into the infusion of 1 × 106/kg CD45RA- memory T cells or the SoC. We selected four unvaccinated donors based on the expression of interferon gamma SARS-CoV-2-specific response within the CD45RA- memory T cells and the most frequent human leukocyte antigen typing in the Spanish population.

RESULTS

We analyzed data from 81 patients. The primary outcome for recovery, defined as the proportion of participants in each group with normalization of fever, oxygen saturation sustained for at least 24 hours and lymphopenia recovery through day 14 or at discharge, was met for the experimental arm. We also observed faster lymphocyte recovery in the experimental group. We did not observe any treatment-related adverse events.

CONCLUSIONS

Adoptive cell therapy with off-the-shelf CD45RA- memory T cells containing SAR-CoV-2-specific T cells is safe, effective and accelerates lymphocyte recovery of patients with COVID-19 pneumonia and/or lymphopenia.

TRIAL REGISTRATION

NCT04578210.

Rationale for combined therapies in severe-to-critical COVID-19 patients

An unprecedented global social and economic impact as well as a significant number of fatalities have been brought on by the coronavirus disease 2019 (COVID-19), produced by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Acute SARS-CoV-2 infection can, in certain situations, cause immunological abnormalities, leading to an anomalous innate and adaptive immune response. While most patients only experience mild symptoms and recover without the need for mechanical ventilation, a substantial percentage of those who are affected develop severe respiratory illness, which can be fatal. The absence of effective therapies when disease progresses to a very severe condition coupled with the incomplete understanding of COVID-19's pathogenesis triggers the need to develop innovative therapeutic approaches for patients at high risk of mortality. As a result, we investigate the potential contribution of promising combinatorial cell therapy to prevent death in critical patients.

The COVID-19 pandemic reveals the wide-ranging role of biobanks

The pandemic of COVID-19 reached an unprecedented scale in terms of spread and deaths, its mitigation required a joint effort of governments, hospitals, private companies and other organizations. One type of organization that could undertake a major role in the process is biobank - a mediator between clinical practice and research. Naturally, biobanks are well equipped to alleviate the burden of a pandemic with their expertise in biospecimen and health information collection, sample preparation and storage, bioethics and project management. Here, we present the participation of Vilnius Santaros Klinikos Biobank (BB VSK), Lithuania in the overall management of the pandemics on the national level. We further discuss the role of biobanks in preparation and management of future pandemics.

SARS-CoV-2-specific T cell therapy for severe COVID-19: a randomized phase 1/2 trial

Despite advances, few therapeutics have shown efficacy in severe coronavirus disease 2019 (COVID-19). In a different context, virus-specific T cells have proven safe and effective. We conducted a randomized (2:1), open-label, phase 1/2 trial to evaluate the safety and efficacy of off-the-shelf, partially human leukocyte antigen (HLA)-matched, convalescent donor-derived severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells (CoV-2-STs) in combination with standard of care (SoC) in patients with severe COVID-19 compared to SoC during Delta variant predominance. After a dose-escalated phase 1 safety study, 90 participants were randomized to receive CoV-2-ST+SoC (n = 60) or SoC only (n = 30). The co-primary objectives of the study were the composite of time to recovery and 30-d recovery rate and the in vivo expansion of CoV-2-STs in patients receiving CoV-2-ST+SoC over SoC. The key secondary objective was survival on day 60. CoV-2-ST+SoC treatment was safe and well tolerated. The study met the primary composite endpoint (CoV-2-ST+SoC versus SoC: recovery rate 65% versus 38%, P = 0.017; median recovery time 11 d versus not reached, P = 0.052, respectively; rate ratio for recovery 1.71 (95% confidence interval 1.03-2.83, P = 0.036)) and the co-primary objective of significant CoV-2-ST expansion compared to SοC (CoV-2-ST+SoC versus SoC, P = 0.047). Overall, in hospitalized patients with severe COVID-19, adoptive immunotherapy with CoV-2-STs was feasible and safe. Larger trials are needed to strengthen the preliminary evidence of clinical benefit in severe COVID-19. EudraCT identifier: 2021-001022-22 .

Potency assessment of IFNγ-producing SARS-CoV-2-specific T cells from COVID-19 convalescent subjects

The development of new therapies for COVID-19 high-risk patients remains necessary to prevent additional deaths. Here, we studied the phenotypical and functional characteristics of IFN-γ producing-SARS-CoV-2-specific T cells (SC2-STs), obtained from 12 COVID-19 convalescent donors, to determine their potency as an off-the-shelf T cell therapy product. We found that these cells present mainly an effector memory phenotype, characterized by the basal expression of cytotoxicity and activation markers, including granzyme B, perforin, CD38, and PD-1. We demonstrated that SC2-STs could be expanded and isolated in vitro, and they exhibited peptide-specific cytolytic and proliferative responses after antigenic re-challenge. Collectively, these data demonstrate that SC2-STs can be a suitable candidate for the manufacture of a T cell therapy product aimed to treat severe COVID-19.

Immune Dynamics Involved in Acute and Convalescent COVID-19 Patients

COVID-19 is a viral disease that has caused millions of deaths around the world since 2020. Many strategies have been developed to manage patients in critical conditions; however, comprehension of the immune system is a key factor in viral clearance, tissue repairment, and adaptive immunity stimulus. Participation of immunity has been identified as a major factor, along with biomarkers, prediction of clinical outcomes, and antibody production after infection. Immune cells have been proposed not only as a hallmark of severity, but also as a predictor of clinical outcomes, while dynamics of inflammatory molecules can also induce worse consequences for acute patients. For convalescent patients, mild disease was related to higher antibody production, although the factors related to the specific antibodies based on a diversity of antigens were not clear. COVID-19 was explored over time; however, the study of immunological predictors of outcomes is still lacking discussion, especially in convalescent patients. Here, we propose a review using previously published studies to identify immunological markers of COVID-19 outcomes and their relation to antibody production to further contribute to the clinical and laboratorial management of patients.

Immune cell landscape in symptomatic and asymptomatic SARS-CoV-2 infected adults and children in urban Dhaka, Bangladesh

OBJECTIVES

The study of cellular immunity to SARS-CoV-2 is crucial for evaluating the course of the COVID-19 disease and for improving vaccine development. We aimed to assess the phenotypic landscape of circulating lymphocytes and mononuclear cells in adults and children who were seropositive to SARS-CoV-2 in the past 6 months.

METHODS

Blood samples (n = 350) were collected in a cross-sectional study in Dhaka, Bangladesh (Oct 2020-Feb 2021). Plasma antibody responses to SARS-CoV-2 were determined by an electrochemiluminescence immunoassay while lymphocyte and monocyte responses were assessed using flow cytometry including dimensionality reduction and clustering algorithms.

RESULTS

SARS-CoV-2 seropositivity was observed in 52% of adults (18-65 years) and 56% of children (10-17 years). Seropositivity was associated with reduced CD3⁺T cells in both adults (beta(β) = -2.86; 95% Confidence Interval (CI) = -5.98, 0.27) and children (β = -8.78; 95% CI = -13.8, -3.78). The frequencies of T helper effector (CD4⁺T_EFF) and effector memory cells (CD4⁺T_EM) were increased in seropositive compared to seronegative children. In adults, seropositivity was associated with an elevated proportion of cytotoxic T central memory cells (CD8⁺T_CM). Overall, diverse manifestations of immune cell dysregulations were more prominent in seropositive children compared to adults, who previously had COVID-like symptoms. These changes involved reduced frequencies of CD4⁺T_EFF cells and CD163⁺CD64⁺ classical monocytes, but increased levels of intermediate or non-classical monocytes, as well as CD8⁺T_EM cells in symptomatic children.

CONCLUSION

Seropositive individuals in convalescence showed increased central and effector memory T cell phenotypes and pro-resolving/healing monocyte phenotypes compared to seronegative subjects. However, seropositive children with a previous history of COVID-like symptoms, displayed an ongoing innate inflammatory trait.

Donor selection for adoptive cell therapy with CD45RA- memory T cells for patients with coronavirus disease 2019, and dexamethasone and interleukin-15 effects on the phenotype, proliferation and interferon gamma release

BACKGROUND AIMS

We have previously demonstrated the safety and feasibility of adoptive cell therapy with CD45RA- memory T cells containing severe acute respiratory syndrome coronavirus 2-specific T cells for patients with coronavirus disease 2019 from an unvaccinated donor who was chosen based on human leukocyte antigen compatibility and cellular response. In this study, we examined the durability of cellular and humoral immunity within CD45RA- memory T cells and the effect of dexamethasone, the current standard of care treatment, and interleukin-15, a cytokine critically involved in T-cell maintenance and survival.

METHODS

We performed a longitudinal analysis from previously severe acute respiratory syndrome coronavirus 2-infected and infection-naïve individuals covering 21 months from infection and 10 months after full vaccination with the BNT162b2 Pfizer/BioNTech vaccine.

RESULTS

We observed that cellular responses are maintained over time. Humoral responses increased after vaccination but were gradually lost. In addition, dexamethasone did not alter cell functionality or proliferation of CD45RA- T cells, and interleukin-15 increased the memory T-cell activation state, regulatory T cell expression, and interferon gamma release.

CONCLUSIONS

Our results suggest that the best donors for adoptive cell therapy would be recovered individuals and 2 months after vaccination, although further studies with larger cohorts would be needed to confirm this finding. Dexamethasone did not affect the characteristics of the memory T cells at a concentration used in the clinical practice and IL-15 showed a positive effect on SARS-CoV-2-specific CD45RA- T cells.

Familial CD45RA- T cells to treat severe refractory infections in immunocompromised patients

Background

Immunocompromised patients are susceptible to high-risk opportunistic infections and malignant diseases. Most antiviral and antifungal drugs are quite toxic, relatively ineffective, and induce resistance in the long term. The transfer of pathogen-specific Cytotoxic T-Lymphocytes has shown a minimal toxicity profile and effectiveness in treating Cytomegalovirus, Adenovirus, Epstein - Barr virus, BK Virus and Aspergillus infections, but this therapy have the main limitations of regulatory issues, high cost, and absence of public cell banks. However, CD45RA^- cells containing pathogen-specific memory T-cells involve a less complex manufacturing and regulatory process and are cheaper, feasible, safe, and potentially effective.

Methods

We present preliminary data from six immunocompromised patients: four who had severe infectious diseases and two who had EBV lymphoproliferative disease. All of them underwent multiple safe familial CD45RA^- T-cell infusions as adoptive passive cell therapy, containing Cytomegalovirus, Epstein - Barr virus, BK virus, and Aspergillus-specific memory T-cells. We also present the method for selecting the best donors for CD45RA^- cells in each case and the procedure to isolate and store these cells.

Results

The infusions were safe, there was no case of graft-versus host disease, and they showed a clear clinical benefit. The patients treated for BK virus nephritis, Cytomegalovirus encephalitis, Cytomegalovirus reactivation, and disseminated invasive aspergillosis experienced pathogen clearance, complete resolution of symptoms in 4-6 weeks and a lymphocyte increase in 3 of 4 cases after 3-4 months. Donor T cell transient microchimerism was detected in one patient. The two patients treated for EBV lymphoproliferative disease underwent chemotherapy and several infusions of CD45RA^- memory T-cells containing EBV cytotoxic lymphocytes. Donor T-cell microchimerism was observed in both patients. The viremia cleared in one of the patients, and in the other, despite the viremia not clearing, hepatic lymphoproliferative disease remained stable and was ultimately cured with EBV-specific Cytotoxic T-Lymphocytes.

Conclusion

The use of familial CD45RA^- T-cells containing specific Cytotoxic T-lymphocytes is a feasible, safe and potential effective approach for treating severe pathogen infections in immunocompromised patients through a third party donor. Furthermore, this approach might be of universal use with fewer institutional and regulatory barriers.

Longevity of memory B cells and antibodies, as well as the polarization of effector memory helper T cells, are associated with disease severity in patients with COVID-19 in Bangladesh

The longevity of immune responses induced by different degrees of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection provides information important to understanding protection against coronavirus disease 2019 (COVID-19). Here, we report the persistence of SARS-CoV-2 spike receptor-binding domain (RBD) specific antibodies and memory B cells recognizing this antigen in sequential samples from patients in Bangladesh with asymptomatic, mild, moderate and severe COVID-19 out to six months following infection. Since the development of long-lived memory B cells, as well as antibody production, is likely to be dependent on T helper (Th) cells, we also investigated the phenotypic changes of Th cells in COVID-19 patients over time following infection. Our results show that patients with moderate to severe COVID-19 mounted significant levels of IgG antibodies out to six months following infection, while patients with asymptomatic or mild disease had significant levels of IgG antibodies out to 3 months following infection, but these then fell more rapidly at 6 months than in patients with higher disease severity. Patients from all severity groups developed circulating memory B cells (MBCs) specific to SARS-CoV-2 spike RBD by 3 months following infection, and these persisted until the last timepoint measured at 6 months. A T helper cell response with an effector memory phenotype was observed following infection in all symptomatic patients, while patients with asymptomatic infection had no significant increases in effector Th1, Th2 and Th17 effector memory cell responses. Our results suggest that the strength and magnitude of antibody and memory B cells induced following SARS-CoV-2 infection depend on the severity of the disease. Polarization of the Th cell response, with an increase in Th effector memory cells, occurs in symptomatic patients by day 7 following infection, with increases seen in Th1, Th2, Th17 and follicular helper T cell subsets.

Central and effector memory T cells in peripheral blood of patients with interstitial pneumonia: preliminary clues from a COVID-19 study

BACKGROUND

SARS-CoV-2 pre-existing T-cell immune reactivity can be present in some people. A general perturbation of the main peripheral lymphocyte subsets has been described in severe COVID-19 patients, but very few studies assessed the general memory T-cell homeostasis in the acute phase of COVID-19. Here, we performed a general analysis of the main memory T cell populations in the peripheral blood of patients admitted to the hospital for a confirmed or probable COVID-19 diagnosis.

METHODS

In this cross-sectional study, adult patients (aged ≥ 18 years) needing hospital admission for respiratory disease due to confirmed or probable COVID-19, were recruited before starting the therapeutic protocol for this disease. In addition to the assessment of the general lymphocyte subpopulations in the early phase of COVID-19, central memory T cells (Tm_centr cells: CD45RO+CCR7+) and effector memory T cells (Tm_eff cells: CD45RO+CCR7-) were assessed by multi-color flow cytometry, in comparison to a control group.

RESULTS

During the study period, 148 study participants were recruited. Among them, 58 patients turned out positive for SARS-CoV-2 PCR (including both patients with interstitial pneumonia [PCR+Pn+] and without this complication [PCR+Pn-]), whereas the remaining 90 patients resulted to be SARS-CoV-2 PCR negative, even though all were affected with interstitial pneumonia [PCR-Pn+]. Additionally, 28 control patients without any ongoing respiratory disease were recruited. A clear unbalance in the T memory compartment emerged from this analysis on the whole pool of T cells (CD3+ cells), showing a significant increase in Tm_centr cells and, conversely, a significant decrease in Tm_eff cells in both pneumonia groups (PCR+Pn+ and PCR-Pn+) compared to the controls; PCR+Pn- group showed trends comprised between patients with pneumonia (from one side) and the control group (from the other side). This perturbation inside the memory T cell compartment was also observed in the individual analysis of the four main T cell subpopulations, based upon the differential expression of CD4 and/or CD8 markers.

CONCLUSION

Overall, we observed both absolute and relative increases of Tm_centr cells and decrease of Tm_eff cells in patients affected with interstitial pneumonia (regardless of the positive or negative results of SARS-CoV-2 PCR), compared to controls. These results need confirmation from additional research, in order to consider this finding as a potential biological marker of interstitial lung involvement in patients affected with viral respiratory infections.

How I treat and prevent COVID-19 in patients with hematologic malignancies and recipients of cellular therapies

Patients with hematologic malignancies and recipients of hematopoietic cell transplantation (HCT) are more likely to experience severe coronavirus disease 2019 (COVID-19) and have a higher risk of morbidity and mortality after infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Compared with the general population, these patients have suboptimal humoral responses to COVID-19 vaccines and subsequently increased risk for breakthrough infections, underscoring the need for additional therapies, including pre- and postexposure prophylaxis, to attenuate clinical progression to severe COVID-19. Therapies for COVID-19 are mostly available for adults and in the inpatient and outpatient settings. Selection and administration of the best treatment options are based on host factors; virus factors, including circulating SARS-CoV-2 variants; and therapeutic considerations, including the clinical efficacy, availability, and practicality of treatment and its associated side effects, including drug-drug interactions. In this paper, we discuss how we approach managing COVID-19 in patients with hematologic malignancies and recipients of HCT and cell therapy.

Zelltherapie in den Zeiten von SARS-CoV-2

Ein breites Spektrum von Disruptionen, aber auch blitzschnelle Innovationen, hat die SARS-CoV-2 Pandemie gebracht. Dieser Übersichtsartikel betrachtet die Pandemie aus der Warte der Zelltherapie; konkret werden vier Aspekte untersucht: Wie unterscheiden sich die Risiken von Zelltherapie-Patienten mit SARS-CoV-2 Infektion und COVID von denen der Allgemeinbevölkerung? Sind Empfänger von Zelltherapien, hier speziell autologe und allogene Stammzelltransplantationsempfänger sowie Empfänger von CAR-T-Zell-Präparaten, klinisch relevant durch SARS-CoV-2 Vakzine immunisierbar? Welche Auswirkungen hat die Pandemie mit Spenderausfallrisiko und Zusammenbruch von Supply Chains auf die Versorgung mit Zelltherapeutika? Gibt es Zelltherapeutika, die bei schwerem COVID therapeutisch nutzbringend eingesetzt werden können? In aller Kürze, das erwartete massiv erhöhte Risiko von Zelltherapie-Patienten, im Infektionsfall einen schweren Verlauf zu erleiden oder zu sterben, wurde bestätigt. Die Vakzine induziert jedoch bei vielen dieser Patienten humorale und zelluläre Immunität, wenn auch weniger zuverlässig als bei Gesunden. Dank kreativer Lösungen gelang es, die Versorgung mit Zelltherapeutika im Wesentlichen uneingeschränkt aufrecht zu erhalten. SARS-CoV-2-spezifische T-Zell-Präparate für den adoptiven Immuntransfer wurden entwickelt, eine therapeutische Konstellation diese anzuwenden ergab sich jedoch nicht. Therapiestudien mit mesenchymalen Stromazellen beim schweren COVID laufen weltweit; die Frage der Wirksamkeit bleibt zurzeit offen, bei jedoch substanziellem Optimismus in der Szene. Einige der Erkenntnisse und Innovationen aus der SARS-CoV-2-Pandemie können möglicherweise verallgemeinert werden und so auf die Zeit nach ihrem Ende langfristig nachwirken.

Alterations of Urinary Microbial Metabolites and Immune Indexes Linked With COVID-19 Infection and Prognosis

Coronavirus disease 2019 (COVID-19) has evolved into an established global pandemic. Metabolomic studies in COVID-19 patients is worth exploring for further available screening methods. In our study, we recruited a study cohort of 350 subjects comprising 248 COVID-19 patients (161 non-severe cases, 60 asymptomatic cases, and 27 severe cases) and 102 healthy controls (HCs), and herein present data with respect to their demographic features, urinary metabolome, immunological indices, and follow-up health status. We found that COVID-19 resulted in alterations of 39 urinary, mainly microbial, metabolites. Using random forest analysis, a simplified marker panel including three microbial metabolites (oxoglutaric acid, indoxyl, and phenylacetamide) was constructed (AUC=0.963, 95% CI, 0.930-0.983), which exhibited higher diagnostic performance than immune feature-based panels between COVID-19 and HC groups (P<0.0001). Meanwhile, we observed that urine metabolic markers enabled discriminating asymptomatic patients (ASY) from HCs (AUC = 0.981, 95% CI, 0.946-0.996), and predicting the incidence of high-risk sequalae in COVID-19 individuals (AUC=0.931, 95% CI, 0.877-0.966). Co-expression network analysis showed that 13 urinary microbial metabolites (e.g., oxoglutaric acid) were significantly correlated with alterations of CD4⁺, CD3⁺, and CD8⁺ T-cells, as well as IFN-γ, IL-2 and IL-4 levels, suggesting close interactions between microbial metabolites and host immune dysregulation in COVID-19. Taken together, our findings indicate that urinary metabolites may have promising potential for screening of COVID-19 in different application scenarios, and provide a new entry point to understand the microbial metabolites and related immune dysfunction in COVID-19.

CD8+ T Cells in SARS-CoV-2 Induced Disease and Cancer-Clinical Perspectives

Dysregulated innate and adaptive immunity is a sign of SARS-CoV-2-induced disease and cancer. CD8+ T cells are important cells of the immune system. The cells belong to the adaptive immunity and take a front-line defense against viral infections and cancer. Extreme CD8+ T-cell activities in the lung of patients with a SARS-CoV-2-induced disease and within the tumor microenvironment (TME) will change their functionality into exhausted state and undergo apoptosis. Such diminished immunity will put cancer cases at a high-risk group for SARS-CoV-2-induced disease, rendering viral sepsis and a more severe condition which will finally cause a higher rate of mortality. Recovering responses from CD8+ T cells is a purpose of vaccination against SARS-CoV-2. The aim of this review is to discuss the CD8+ T cellular state in SARS-CoV-2-induced disease and in cancer and to present some strategies for recovering the functionality of these critical cells.

Rifampicin for COVID-19

Vaccinations for coronavirus disease-2019 (COVID-19) have begun more than a year before, yet without specific treatments available. Rifampicin, critically important for human medicine (World Health Organization’s list of essential medicines), may prove pharmacologically effective for treatment and chemoprophylaxis of healthcare personnel and those at higher risk. It has been known since 1969 that rifampicin has a direct selective antiviral effect on viruses which have their own RNA polymerase (severe acute respiratory syndrome coronavirus 2), like the main mechanism of action of remdesivir. This involves inhibition of late viral protein synthesis, the virion assembly, and the viral polymerase itself. This antiviral effect is dependent on the administration route, with local application resulting in higher drug concentrations at the site of viral replication. This would suggest also trying lung administration of rifampicin by nebulization to increase the drug’s concentration at infection sites while minimizing systemic side effects. Recent in silico studies with a computer-aided approach, found rifampicin among the most promising existing drugs that could be repurposed for the treatment of COVID-19.

SARS-CoV-2 variant B.1.1.7 caused HLA-A2+ CD8+ T cell epitope mutations for impaired cellular immune response

Here, we evaluated the immune properties of the HLA-A2 restricted CD8+ T cell epitopes containing mutations from B.1.1.7, and furthermore performed a comprehensive analysis of the SARS-CoV-2 specific CD8+ T cell responses from COVID-19 convalescent patients and SARS-CoV-2 vaccinees recognizing the ancestral Wuhan strain compared to B.1.1.7. First, most of the predicted CD8+ T cell epitopes showed proper binding with HLA-A2, whereas epitopes from B.1.1.7 had lower binding capability than those from the ancestral strain. In addition, these peptides could effectively induce the activation and cytotoxicity of CD8+ T cells. Our results further showed that at least two site mutations in B.1.1.7 resulted in a decrease in CD8+ T cell activation and a possible immune evasion, namely A1708D mutation in ORF1ab1707-1716 and I2230T mutation in ORF1ab2230-2238. Our current analysis provides information that contributes to the understanding of SARS-CoV-2-specific CD8+ T cell responses elicited by infection of mutated strains or vaccination.

Isolation of Functional SARS-CoV-2 Antigen-Specific T-Cells with Specific Viral Cytotoxic Activity for Adoptive Therapy of COVID-19

In order to demonstrate the feasibility of preparing clinical-grade SARS-CoV-2-specific T-cells from convalescent donors and the ability of these cells to neutralize the virus in vitro, we used blood collected from two COVID-19 convalescent donors (before and after vaccination) that was stimulated with specific SARS-CoV-2 peptides followed by automated T-cell isolation using the CliniMacs Prodigy medical device. To determine cytotoxic activity, HEK 293T cells were transfected to express the SARS-CoV-2 M protein, mimicking SARS-CoV-2 infection. We were able to quickly and efficiently isolate SARS-CoV-2-specific T lymphocytes from both donors before and after they received the Pfizer-BioNTech vaccine. Althoughbefore vaccination, the final product contained up to 7.42% and 30.19% of IFN-γ+ CD3+ T-cells from donor 1 and donor 2, respectively, we observed an enrichment of the IFN-γ+ CD3+ T-cells after vaccination, reaching 70.47% and 42.59%, respectively. At pre-vaccination, the isolated SARS-CoV-2-specific T-cells exhibited cytotoxic activity that was significantly higher than that of unstimulated controls (donor 2: 15.41%, p-value 3.27 × 10⁻³). The cytotoxic activity of the isolated SARS-CoV-2-specific T-cells also significantly increased after vaccination (donor 1: 32.71%, p-value 1.44 × 10⁻⁵; donor 2: 33.38%, p-value 3.13 × 10⁻⁶). In conclusion, we demonstrated that SARS-CoV-2-specific T-cells can quickly and efficiently be stimulated from the blood of convalescent donors using SARS-CoV-2-specific peptides followed by automated isolation. Vaccinated convalescent donors have a higher percentage of SARS-CoV-2-specific T-cells and may be more suitable as donors. Although further studies are needed to assess the clinical utility of the functional isolated SARS-CoV-2-specific T-cells in patients, previous studies using the same stimulation and isolation methods applied to other pathologies support this idea.

Respiratory Infections in Patients with Primary Immunodeficiency

Recurrent and life-threatening respiratory infections are nearly universal in patients with primary immunodeficiency diseases (PIDD). Early recognition, aggressive treatment, and prophylaxis with antimicrobials and immunoglobulin replacement have been the mainstays of management and will be reviewed here with an emphasis on respiratory infections. Genetic discoveries have allowed direct translation of research to clinical practice, improving our understanding of clinical patterns of pathogen susceptibilities and guiding prophylaxis. The recent identification of inborn errors in type I interferon signaling as a basis for life-threatening viral infections in otherwise healthy individuals suggests another targetable pathway for treatment and/or prophylaxis. The future of PIDD diagnosis will certainly involve early genetic identification by newborn screening before onset of infections, with early treatment offering the potential of preventing disease complications such as chronic lung changes. Gene editing approaches offer tremendous therapeutic potential, with rapidly emerging delivery systems. Antiviral therapies are desperately needed, and specific cellular therapies show promise in patients requiring hematopoietic stem cell transplantation. The introduction of approved therapies for clinical use in PIDD is limited by the difficulty of studying outcomes in rare patients/conditions with conventional clinical trials.

SARS-CoV-2-specific T cells generated for adoptive immunotherapy are capable of recognizing multiple SARS-CoV-2 variants

Adoptive T-cell immunotherapy has provided promising results in the treatment of viral complications in humans, particularly in the context of immunocompromised patients who have exhausted all other clinical options. The capacity to expand T cells from healthy immune individuals is providing a new approach to anti-viral immunotherapy, offering rapid off-the-shelf treatment with tailor-made human leukocyte antigen (HLA)-matched T cells. While most of this research has focused on the treatment of latent viral infections, emerging evidence that SARS-CoV-2-specific T cells play an important role in protection against COVID-19 suggests that the transfer of HLA-matched allogeneic off-the-shelf virus-specific T cells could provide a treatment option for patients with active COVID-19 or at risk of developing COVID-19. We initially screened 60 convalescent individuals and based on HLA typing and T-cell response profile, 12 individuals were selected for the development of a SARS-CoV-2-specific T-cell bank. We demonstrate that these T cells are specific for up to four SARS-CoV-2 antigens presented by a broad range of both HLA class I and class II alleles. These T cells show consistent functional and phenotypic properties, display cytotoxic potential against HLA-matched targets and can recognize HLA-matched cells infected with different SARS-CoV-2 variants. These observations demonstrate a robust approach for the production of SARS-CoV-2-specific T cells and provide the impetus for the development of a T-cell repository for clinical assessment.

Since the emergence of SARS-CoV-2 variants that reduce the effectiveness of vaccines, it is evident that other interventional strategies will be needed to treat COVID-19, particularly in patients with a compromised immune system who are at an increased risk of developing severe COVID-19. Off-the-shelf T-cell immunotherapy is proving to be a powerful tool to treat viral disease in patients with a compromised immune system. Here, we report here that a small number of SARS-CoV-2 exposed individuals can be used generate a bank of specific T cells that provide broad population coverage. Importantly, we demonstrate that most of the epitopes recognized by these T cells remain unchanged in different variants and that the T cells can recognize cells infected with three different variants of SARS-CoV-2. We believe these observations provide critical proof-of-concept that T-cell based immunotherapy may offer an option for the future treatment of immunocompromised patients who remain susceptible to the severe complications associated with COVID-19.

Kinetics and persistence of cellular and humoral immune responses to SARS-CoV-2 vaccine in healthcare workers with or without prior COVID-19

SARS‐CoV‐2 vaccines are highly efficient against severe forms of the disease, hospitalization and death. Nevertheless, insufficient protection against several circulating viral variants might suggest waning immunity and the need for an additional vaccine dose. We conducted a longitudinal study on the kinetics and persistence of immune responses in healthcare workers vaccinated with two doses of BNT162b2 mRNA vaccine with or without prior SARS‐CoV‐2 infection. No new infections were diagnosed during follow‐up. At 6 months, post‐vaccination or post‐infection, despite a downward trend in the level of anti‐S IgG antibodies, the neutralizing activity does not decrease significantly, remaining higher than 75% (85.14% for subjects with natural infection, 88.82% for vaccinated after prior infection and 78.37% for vaccinated only). In a live‐virus neutralization assay, the highest neutralization titres were present at baseline and at 6 months follow‐up in persons vaccinated after prior infection. Anti‐S IgA levels showed a significant descending trend in vaccinated subjects (p < 0.05) after 14 weeks. Cellular immune responses are present even in vaccinated participants with declining antibody levels (index ratio 1.1–3) or low neutralizing activity (30%–40%) at 6 months, although with lower T‐cell stimulation index (p = 0.046) and IFN‐γ secretion (p = 0.0007) compared to those with preserved humoral responses.

Off-the-Shelf Partial HLA Matching SARS-CoV-2 Antigen Specific T Cell Therapy: A New Possibility for COVID-19 Treatment

Background

Immunological characteristics of COVID-19 show pathological hyperinflammation associated with lymphopenia and dysfunctional T cell responses. These features provide a rationale for restoring functional T cell immunity in COVID-19 patients by adoptive transfer of SARS-CoV-2 specific T cells.

Methods

To generate SARS-CoV-2 specific T cells, we isolated peripheral blood mononuclear cells from 7 COVID-19 recovered and 13 unexposed donors. Consequently, we stimulated cells with SARS-CoV-2 peptide mixtures covering spike, membrane and nucleocapsid proteins. Then, we culture expanded cells with IL-2 for 21 days. We assessed immunophenotypes, cytokine profiles, antigen specificity of the final cell products.

Results

Our results show that SARS-CoV-2 specific T cells could be expanded in both COVID-19 recovered and unexposed groups. Immunophenotypes were similar in both groups showing CD4+ T cell dominance, but CD8+ and CD3+CD56+ T cells were also present. Antigen specificity was determined by ELISPOT, intracellular cytokine assay, and cytotoxicity assays. One out of 14 individuals who were previously unexposed to SARS-CoV-2 failed to show antigen specificity. Moreover, ex-vivo expanded SARS-CoV-2 specific T cells mainly consisted of central and effector memory subsets with reduced alloreactivity against HLA-unmatched cells suggesting the possibility for the development of third-party partial HLA-matching products.

Discussion

In conclusion, our findings show that SARS-CoV-2 specific T cell can be readily expanded from both COVID-19 and unexposed individuals and can therefore be manufactured as a biopharmaceutical product to treat severe COVID-19 patients.

One Sentence Summary

Ex-vivo expanded SARS-CoV-2 antigen specific T cells developed as third-party partial HLA-matching products may be a promising approach for treating severe COVID-19 patients that do not respond to previous treatment options.

T Cell Immunity Evaluation and Immunodominant Epitope T Cell Receptor Identification of Severe Acute Respiratory Syndrome Coronavirus 2 Spike Glycoprotein in COVID-19 Convalescent Patients

A better understanding of the role of T cells in the immune response to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is helpful not only for vaccine development but also for the treatment of COVID-19 patients. In this study, we determined the existence of SARS-CoV-2-specific T cells in the blood of COVID-19 convalescents. Meanwhile, the specific T cell response in the non-RBD region was stronger than in the RBD region. We also found that SARS-CoV-2 S-specific reactive CD4⁺ T cells exhibited higher frequency than CD8⁺ T cells in recovered COVID-19 patients, with greater number of corresponding epitopes presented. Importantly, we isolated the SARS-CoV-2-specific CD4⁺ T cell receptors (TCRs) and inserted the TCRs into allogenic CD4⁺ T cells. These TCR-T cells can be activated by SARS-CoV-2 spike peptide and produce IFN-γ in vitro. These results might provide valuable information for the development of vaccines and new therapies against COVID-19.

Identifying SARS-CoV-2 'memory' NK cells from COVID-19 convalescent donors for adoptive cell therapy

COVID-19 disease is the manifestation of syndrome coronavirus 2 (SARS-CoV-2) infection, which is causing a worldwide pandemic. This disease can lead to multiple and different symptoms, being lymphopenia associated with severity one of the most persistent. Natural killer cells (NK cells) are part of the innate immune system, being fighting against virus-infected cells one of their key roles. In this study, we determined the phenotype of NK cells after COVID-19 and the main characteristic of SARS-CoV-2-specific-like NK population in the blood of convalescent donors. CD57+ NKG2C+ phenotype in SARS-CoV-2 convalescent donors indicates the presence of 'memory'/activated NK cells as it has been shown for cytomegalovirus infections. Although the existence of this population is donor dependent, its expression may be crucial for the specific response against SARS-CoV-2, so that, it gives us a tool for selecting the best donors to produce off-the-shelf living drug for cell therapy to treat COVID-19 patients under the RELEASE clinical trial (NCT04578210).

Recent Advances of COVID-19 Modeling Based on Regenerative Medicine

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has caused a pandemic since December 2019 that originated in Wuhan, China. Soon after that, the world health organization declared Coronavirus disease-2019 a global health concern. SARS-CoV-2 is responsible for a lethal respiratory infection as well as the involvement of other organs due to its large tropism spectrum such as neurologic, cardiovascular, endocrine, gastrointestinal, and renal systems. Since the behavior of the virus is not fully understood, a new manifestation of the infection is revealed every day. In order to be able to design more efficient drugs and vaccines to treat the infection, finding out the exact mechanism of pathogenicity would be necessary. Although there have been some big steps toward understanding the relevant process, there are still some deficiencies in this field. Accordingly, regenerative medicine (RM), can offer promising opportunities in discovering the exact mechanisms and specific treatments. For instance, since it is not always possible to catch the pathophysiology mechanisms in human beings, several modeling methods have been introduced in this field that can be studied in three main groups: stem cell-based models, organoids, and animal models. Regarding stem cell-based models, induced pluripotent stem cells are the major study subjects, which are generated by reprogramming the somatic stem cells and then directing them into different adult cell populations to study their behavior toward the infection. In organoid models, different cell lines can be guided to produce a 3D structure including liver, heart, and brain-like platforms. Among animal models, mice are the most common species in this field. However, in order for mice models to be permissive to the virus, angiotensin-converting enzyme 2 receptors, the main receptor involved in the pathogenicity of the virus, should be introduced to the host cells through different methods. Here, the current known mechanism of SARS-CoV-2 infection, different suggested models, the specific response toward different manipulation as well as challenges and shortcomings in each case have been reviewed. Finally, we have tried to provide a quick summary of the present available RM-based models for SARS-CoV-2 infection, as an essential part of developing drugs, for future therapeutic goals.

A phase I/II dose-escalation multi-center study to evaluate the safety of infusion of natural killer cells or memory T cells as adoptive therapy in coronavirus pneumonia and/or lymphopenia: RELEASE study protocol

BACKGROUND

Moderate/severe cases of COVID-19 present a dysregulated immune system with T cell lymphopenia and a hyper-inflammatory state. This is a study protocol of an open-label, multi-center, double-arm, randomized, dose-finding phase I/II clinical trial to evaluate the safety, tolerability, alloreactivity, and efficacy of the administration of allogeneic memory T cells and natural killer (NK) cells in COVID-19 patients with lymphopenia and/or pneumonia. The aim of the study is to determine the safety and the efficacy of the recommended phase 2 dose (RP2D) of this treatment for patients with moderate/severe COVID-19.

METHODS

In the phase I trial, 18 patients with COVID-19-related pneumonia and/or lymphopenia with no oxygen requirement or with an oxygen need of ≤ 2.5 liters per minute (lpm) in nasal cannula will be assigned to two arms, based on the biology of the donor and the patient. Treatment of arm A consists of the administration of escalating doses of memory T cells, plus standard of care (SoC). Treatment of arm B consists of the administration of escalating doses of NK cells, plus SoC. In the phase II trial, a total of 182 patients with COVID-19-related pneumonia and/or lymphopenia requiring or not oxygen supplementation but without mechanical ventilation will be allocated to arm A or B, considering HLA typing. Within each arm, they will be randomized in a 1:1 ratio. In arm A, patients will receive SoC or RP2D for memory T cells plus the SoC. In arm B, patients will receive SoC or RP2D for NK cells plus the SoC.

DISCUSSION

We hypothesized that SARS-CoV-2-specific memory T-lymphocytes obtained from convalescent donors recovered from COVID-19 can be used as a passive cell immunotherapy to treat pneumonia and lymphopenia in moderate/severe patients. The lymphopenia induced by COVID-19 constitutes a therapeutic window that may facilitate donor engraftment and viral protection until recovery.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04578210 . First Posted : October 8, 2020.

Cellular Immunotherapy and the Lung

The new era of cellular immunotherapies has provided state-of-the-art and efficient strategies for the prevention and treatment of cancer and infectious diseases. Cellular immunotherapies are at the forefront of innovative medical care, including adoptive T cell therapies, cancer vaccines, NK cell therapies, and immune checkpoint inhibitors. The focus of this review is on cellular immunotherapies and their application in the lung, as respiratory diseases remain one of the main causes of death worldwide. The ongoing global pandemic has shed a new light on respiratory viruses, with a key area of concern being how to combat and control their infections. The focus of cellular immunotherapies has largely been on treating cancer and has had major successes in the past few years. However, recent preclinical and clinical studies using these immunotherapies for respiratory viral infections demonstrate promising potential. Therefore, in this review we explore the use of multiple cellular immunotherapies in treating viral respiratory infections, along with investigating several routes of administration with an emphasis on inhaled immunotherapies.

Phase I dose-escalation single centre clinical trial to evaluate the safety of infusion of memory T cells as adoptive therapy in COVID-19 (RELEASE)

BACKGROUND

Effective treatments are still needed to reduce the severity of symptoms, time of hospitalization, and mortality of COVID-19. SARS-CoV-2 specific memory T-lymphocytes obtained from convalescent donors recovered can be used as passive cell immunotherapy.

METHODS

Between September and November 2020 a phase 1, dose-escalation, single centre clinical trial was conducted to evaluate the safety and feasibility of the infusion of CD45RA^- memory T cells containing SARS-CoV-2 specific T cells as adoptive cell therapy against moderate/severe cases of COVID-19. Nine participants with pneumonia and/or lymphopenia and with at least one human leukocyte antigen (HLA) match with the donor were infused. The first three subjects received the lowest dose (1 × 10⁵ cells/kg), the next three received the intermediate dose (5 × 10⁵ cells/kg) and the last three received the highest dose (1 × 10⁶ cells/kg) of CD45RA^- memory T cells. Clinicaltrials.gov registration: NCT04578210.

FINDINGS

All participants' clinical status measured by National Early Warning Score (NEWS) and 7-category point ordinal scales showed improvement six days after infusion. No serious adverse events were reported. Inflammatory parameters were stabilised post-infusion and the participants showed lymphocyte recovery two weeks after the procedure. Donor microchimerism was observed at least for three weeks after infusion in all patients.

INTERPRETATION

This study provides preliminary evidence supporting the idea that treatment of COVID-19 patients with moderate/severe symptoms using convalescent CD45RA^- memory T cells is feasible and safe.

FUNDING

Clinical Trial supported by Spanish Clinical Research Network PT17/0017/0013. Co-funded by European Regional Development Fund/European Social Fund. CRIS CANCER Foundation Grant to AP-M and Agencia Valenciana de Innovación Grant AVI-GVA COVID-19-68 to BS.

COVID-19 Pathology on Various Organs and Regenerative Medicine and Stem Cell-Based Interventions

Severe acute respiratory syndrome-coronavirus 2, a novel betacoronavirus, has caused the global outbreak of a contagious infection named coronavirus disease-2019. Severely ill subjects have shown higher levels of pro-inflammatory cytokines. Cytokine storm is the term that can be used for a systemic inflammation leading to the production of inflammatory cytokines and activation of immune cells. In coronavirus disease-2019 infection, a cytokine storm contributes to the mortality rate of the disease and can lead to multiple-organ dysfunction syndrome through auto-destructive responses of systemic inflammation. Direct effects of the severe acute respiratory syndrome associated with infection as well as hyperinflammatory reactions are in association with disease complications. Besides acute respiratory distress syndrome, functional impairments of the cardiovascular system, central nervous system, kidneys, liver, and several others can be mentioned as the possible consequences. In addition to the current therapeutic approaches for coronavirus disease-2019, which are mostly supportive, stem cell-based therapies have shown the capacity for controlling the inflammation and attenuating the cytokine storm. Therefore, after a brief review of novel coronavirus characteristics, this review aims to explain the effects of coronavirus disease-2019 cytokine storm on different organs of the human body. The roles of stem cell-based therapies on attenuating cytokine release syndrome are also stated.