Reconstitution of norovirus-specific T cell responses following hematopoietic stem cell transplantation in patients with inborn errors of immunity and chronic norovirus infection.

BACKGROUND: Chronic norovirus infection (CNI) causes significant morbidity in immunocompromised patients. No effective prevention or treatment currently exists. METHODS: Two patients with inborn errors of immunity, X- linked severe combined immunodeficiency (X-SCID) and DOCK8 deficiency, were followed longitudinally for clinical course, immune reconstitution, norovirus-specific T cell (NST) response, B cell reconstitution, and norovirus-specific antibody production. Samples were obtained in the peri-hematopoietic stem cell transplant setting (HSCT) before and after CNI clearance. The norovirus strain causing CNI was followed longitudinally for norovirus stool viral loads and sequencing. RESULTS: The noroviruses were identified as GII.4 Sydney[P4 New Orleans] in one patient and GII.17[P17] in the other. An exacerbation of diarrhea post-HSCT in the patient with X-SCID was consistent with norovirus infection but not with graft-vs-host-disease on pathologic samples. Both patients recovered polyfunctional NSTs in the CD4 and CD8 T cell compartments which recognized multiple norovirus structural and non-structural viral antigens. T cell responses were minimal during active CNI but detectable after resolution. Mapping of norovirus-specific T cell responses between the patient with DOCK8 and his matched sibling donor were nearly identical. B cell reconstitution or new endogenous antibody production for IgA or IgG were not observed. CONCLUSION: This report is the first to demonstrate reconstitution of norovirus-specific T cell immunity after HSCT closely temporally aligned with clearance of CNI suggesting that cellular immunity is sufficient for norovirus clearance.

Third-party virus-specific T cells for the treatment of double-stranded DNA viral reactivation and posttransplant lymphoproliferative disease after solid organ transplant.

Reactivation or primary infection with double-stranded DNA viruses is common in recipients of solid organ transplants (SOTs) and is associated with significant morbidity and mortality. Treatment with conventional antiviral medications is limited by toxicities, resistance, and a lack of effective options for adenovirus (ADV) and BK polyomavirus (BKPyV). Virus-specific T cells (VSTs) have been shown to be an effective treatment for infections with ADV, BKPyV, cytomegalovirus (CMV), and Epstein-Barr virus (EBV). Most of these studies have been conducted in stem cell recipients, and no large studies have been published in the SOT population to date. In this study, we report on the outcome of quadrivalent third-party VST infusions in 98 recipients of SOTs in the context of an open-label phase 2 trial. The 98 patients received a total of 181 infusions, with a median of 2 infusions per patient. The overall response rate was 45% for BKPyV, 65% for cytomegalovirus, 68% for ADV, and 61% for Epstein-Barr virus. Twenty percent of patients with posttransplant lymphoproliferative disorder had a complete response and 40% of patients had a partial response. All the VST infusions were well tolerated. We conclude that VSTs are safe and effective in the treatment of viral infections in SOT recipients.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium.

BACKGROUND: Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18. METHODS: We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity. FINDINGS: For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival. INTERPRETATION: Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID. FUNDING: National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

Cellular therapies for the treatment and prevention of SARS-CoV-2 infection.

Patients with blood disorders who are immune suppressed are at increased risk for infection with severe acute respiratory syndrome coronavirus 2. Sequelae of infection can include severe respiratory disease and/or prolonged duration of viral shedding. Cellular therapies may protect these vulnerable patients by providing antiviral cellular immunity and/or immune modulation. In this recent review of the field, phase 1/2 trials evaluating adoptive cellular therapies with virus-specific T cells or natural killer cells are described along with trials evaluating the safety, feasibility, and preliminary efficacy of immune modulating cellular therapies including regulatory T cells and mesenchymal stromal cells. In addition, the immunologic basis for these therapies is discussed.

Implementation of a tier system for IVIG indications to address IVIG shortage at a tertiary care pediatric medical center.

BACKGROUND: Drug shortages are a common issue that healthcare systems face and can result in adverse health outcomes for patients requiring inferior alternate treatment. The United States recently experienced a national drug shortage of intravenous immunoglobulin (IVIG). Several reported strategies to address the IVIG and other drug shortages have been proposed; however, there is a lack of evidence-based methods for protocol development and implementation. OBJECTIVE: To evaluate the efficacy of introducing a multidisciplinary task force and tier system of indications and to minimize adverse effects during a shortage of IVIG. METHODS: Faculty members across disciplines with expertise in IVIG use were invited to participate in a task force to address the shortage and ensure adequate supply for emergent indications. A tier system of IVIG indications was established according to the severity of diagnosis, urgency of indication, and quality of supporting evidence. Based on inventory, indications in selected tiers were auto-approved. Orders that could not be automatically approved were escalated for task force review. RESULTS: Overall, there were 342 distinct requests for IVIG during the study period (August 1, 2019 to December 31, 2019). All Tier 1 indications were approved. Of all requests, only 2.6% (9) of requests were denied, none of which resulted in adverse effects based on retrospective chart review. Seven patients who regularly receive IVIG had possible adverse effects due to dose reduction or spacing of treatment; however, each complication was multifactorial and not attributed to the shortage or tier system implementation alone. CONCLUSION: Implementation of a multidisciplinary task force and tier system to appropriately triage high-priority indications for limited pharmaceutical agents should be considered in health institutions faced with a drug shortage.

A Heterozygous Gain-of-Function Variant in IKBKB Associated with Autoimmunity and Autoinflammation.

PURPOSE: Biallelic loss-of-function variants in IKBKB cause severe combined immunodeficiency. We describe a case of autoimmunity and autoinflammation in a male infant with a heterozygous gain-of-function (GOF) IKBKB variant. METHODS: Case report and review of the literature. We performed in silico variant analysis, measurement of plasma soluble biomarkers associated with immune activation, functional stimulation of patient peripheral blood mononuclear cells, and functional validation of variants transduced in Jurkat cells. RESULTS: A patient with two heterozygous IKBKB variants (E518K and T559M) presents with previously undescribed autoimmune cytopenias and autoinflammation. He had decreased TNF-α-induced IkBα degradation in vitro, and had increased serum biomarkers associated with macrophage recruitment and activation. Jurkat cells transduced with the IKKb T559M variant showed increased basal levels of phosphorylation of IKKα/b and p65, and higher degradation of IkBα suggesting a GOF mechanism. No significant changes were observed in Jurkat cells transduced with the E518K variant. CONCLUSIONS: A GOF variant in IKBKB may associate with autoinflammation and autoimmunity highlighting a novel clinical phenotype.

FOXI3 haploinsufficiency contributes to low T-cell receptor excision circles and T-cell lymphopenia.

BACKGROUND: Newborn screening can identify neonatal T-cell lymphopenia through detection of a low number of copies of T-cell receptor excision circles in dried blood spots collected at birth. After a positive screening result, further diagnostic testing is required to determine whether the subject has severe combined immunodeficiency or other causes of T-cell lymphopenia. Even after thorough evaluation, approximately 15% of children with a positive result of newborn screening for T-cell receptor excision circles remain genetically undiagnosed. Identifying the underlying genetic etiology is necessary to guide subsequent clinical management and family planning. OBJECTIVE: We sought to elucidate the genetic basis of patients with T-cell lymphopenia without an apparent genetic diagnosis. METHODS: We used clinical genomic testing as well as functional and immunologic assays to identify and elucidate the genetic and mechanistic basis of T-cell lymphopenia. RESULTS: We report 2 unrelated individuals with nonsevere T-cell lymphopenia and abnormal T-cell receptor excision circles who harbor heterozygous loss-of-function variants in forkhead box I3 transcription factor (FOXI3). CONCLUSION: Our findings support the notion that haploinsufficiency of FOXI3 results in T-cell lymphopenia with variable expressivity and that FOXI3 may be a key modulator of thymus development.

Molecular diagnosis of childhood immune dysregulation, polyendocrinopathy, and enteropathy, and implications for clinical management.

BACKGROUND: Most patients with childhood-onset immune dysregulation, polyendocrinopathy, and enteropathy have no genetic diagnosis for their illness. These patients may undergo empirical immunosuppressive treatment with highly variable outcomes. OBJECTIVE: We sought to determine the genetic basis of disease in patients referred with Immune dysregulation, polyendocrinopathy, enteropathy, X-linked-like (IPEX-like) disease, but with no mutation in FOXP3; then to assess consequences of genetic diagnoses for clinical management. METHODS: Genomic DNA was sequenced using a panel of 462 genes implicated in inborn errors of immunity. Candidate mutations were characterized by genomic, transcriptional, and (for some) protein analysis. RESULTS: Of 123 patients with FOXP3-negative IPEX-like disease, 48 (39%) carried damaging germline mutations in 1 of the following 27 genes: AIRE, BACH2, BCL11B, CARD11, CARD14, CTLA4, IRF2BP2, ITCH, JAK1, KMT2D, LRBA, MYO5B, NFKB1, NLRC4, POLA1, POMP, RAG1, SH2D1A, SKIV2L, STAT1, STAT3, TNFAIP3, TNFRSF6/FAS, TNRSF13B/TACI, TOM1, TTC37, and XIAP. Many of these genes had not been previously associated with an IPEX-like diagnosis. For 42 of the 48 patients with genetic diagnoses, knowing the critical gene could have altered therapeutic management, including recommendations for targeted treatments and for or against hematopoietic cell transplantation. CONCLUSIONS: Many childhood disorders now bundled as "IPEX-like" disease are caused by individually rare, severe mutations in immune regulation genes. Most genetic diagnoses of these conditions yield clinically actionable findings. Barriers are lack of testing or lack of repeat testing if older technologies failed to provide a diagnosis.

Natural history of infants with non-SCID T cell lymphopenia identified on newborn screen.

Newborn screening (NBS) for severe combined immunodeficiency (SCID) can identify infants with non-SCID T cell lymphopenia (TCL). The purpose of this study was to characterize the natural history and genetic findings of infants with non-SCID TCL identified on NBS. We analyzed data from 80 infants with non-SCID TCL in the mid-Atlantic region between 2012 and 2019. 66 patients underwent genetic testing and 41 (51%) had identified genetic variant(s). The most common genetic variants were thymic defects (33%), defects with unknown mechanisms (12%) and bone marrow production defects (5%). The genetic cohort had significantly lower median initial CD3+, CD4+, CD8+ and CD4/CD45RA+ T cell counts compared to the non-genetic cohort. Thirty-six (45%) had either viral, bacterial, or fungal infection; only one patient had an opportunistic infection (vaccine strain VZV infection). Twenty-six (31%) of patients had resolution of TCL during the study period.

Virus-specific T-cell therapies for patients with primary immune deficiency.

Viral infections are common and are potentially life-threatening in patients with moderate to severe primary immunodeficiency disorders. Because T-cell immunity contributes to the control of many viral pathogens, adoptive immunotherapy with virus-specific T cells (VSTs) has been a logical and effective way of combating severe viral disease in immunocompromised patients in multiple phase 1 and 2 clinical trials. Common viral targets include cytomegalovirus, Epstein-Barr virus, and adenovirus, though recent published studies have successfully targeted additional pathogens, including HHV6, BK virus, and JC virus. Though most studies have used VSTs derived from allogenic stem cell donors, the use of banked VSTs derived from partially HLA-matched donors has shown efficacy in multicenter settings. Hence, this approach could shorten the time for patients to receive VST therapy thus improving accessibility. In this review, we discuss the usage of VSTs for patients with primary immunodeficiency disorders in clinical trials, as well as future potential targets and methods to broaden the applicability of virus-directed T-cell immunotherapy for this vulnerable patient population.

SARS-CoV-2-specific T cells are rapidly expanded for therapeutic use and target conserved regions of the membrane protein.

T-cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described in recovered patients, and may be important for immunity following infection and vaccination as well as for the development of an adoptive immunotherapy for the treatment of immunocompromised individuals. In this report, we demonstrate that SARS-CoV-2-specific T cells can be expanded from convalescent donors and recognize immunodominant viral epitopes in conserved regions of membrane, spike, and nucleocapsid. Following in vitro expansion using a good manufacturing practice-compliant methodology (designed to allow the rapid translation of this novel SARS-CoV-2 T-cell therapy to the clinic), membrane, spike, and nucleocapsid peptides elicited interferon-γ production, in 27 (59%), 12 (26%), and 10 (22%) convalescent donors (respectively), as well as in 2 of 15 unexposed controls. We identified multiple polyfunctional CD4-restricted T-cell epitopes within a highly conserved region of membrane protein, which induced polyfunctional T-cell responses, which may be critical for the development of effective vaccine and T-cell therapies. Hence, our study shows that SARS-CoV-2 directed T-cell immunotherapy targeting structural proteins, most importantly membrane protein, should be feasible for the prevention or early treatment of SARS-CoV-2 infection in immunocompromised patients with blood disorders or after bone marrow transplantation to achieve antiviral control while mitigating uncontrolled inflammation.

Excellent outcomes following hematopoietic cell transplantation for Wiskott-Aldrich syndrome: a PIDTC report.

Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients <5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism <50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full (>95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.).

Spike-directed vaccination elicits robust spike-specific T-cell response, including to mutant strains.

Although most studies describing coronavirus disease 2019 vaccine responses have focused on antibodies, there is increasing evidence that T cells play a critical role. Here the authors evaluated T-cell responses in seronegative donors before and after vaccination to define responses to the severe acute respiratory syndrome coronavirus 2 reference strain as well as to mutations in the variant strains Alpha/B.1.1.7 and Beta/B.1.351. The authors observed enhanced T-cell responses to reference and variant spike strains post-vaccination.

Immunizing the imperfect immune system: Coronavirus disease 2019 vaccination in patients with inborn errors of immunity.

OBJECTIVE: To update clinicians on current evidence regarding the immunogenicity and safety of coronavirus disease 2019 (COVID-19) vaccines in patients with inborn errors of immunity (IEI). DATA SOURCES: Peer-reviewed, published studies in PubMed, clinical trials listed on ClinicalTrials.gov, and professional organization and governmental guidelines. STUDY SELECTIONS: Literature searches on PubMed and ClinicalTrials.gov were performed using a combination of the following keywords: primary immunodeficiency, COVID-19, SARS-CoV-2, and vaccination. RESULTS: A total of 26 studies met the criteria and were included in this review. Overall, antibody responses to COVID-19 vaccination were found in 72% of study subjects, with stronger responses observed after messenger RNA vaccination. Neutralizing antibodies were detected in patients with IEI, though consistently at lower levels than healthy controls. Risk factors for poor antibody responses included diagnosis of common variable immunodeficiency, presence of autoimmune comorbidities, and use of rituximab. T cell responses were detectable in most patients with IEI, with poorer responses often found in patients with common variable immunodeficiency. Safety of COVID-19 vaccines in patients with IEI was acceptable with high rates of reactogenicity but very few serious adverse events, including in patients with immune dysregulation. CONCLUSION: COVID-19 vaccines are safe in patients with IEI and seem to be immunogenic in most individuals, with stronger responses found after messenger RNA vaccinations.

Robust immune responses to SARS-CoV-2 in a pediatric patient with B-Cell ALL receiving tisagenlecleucel.

Recipients of anti-CD19 targeted therapies such as chimeric antigen receptor (CAR)-T cell are considered at high risk for complicated Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) infection due to prolonged B cell aplasia and immunosuppression. These patients represent a unique cohort and so far, immune responses to SARS-CoV-2 have not been well characterized in this setting. We report a pediatric patient with B-cell acute lymphoblastic leukemia (B-ALL) who had asymptomatic SARS-CoV-2 infection while receiving blinatumomab, followed by lymphodepletion (LD) and tisagenlecleucel, a CD19 targeting CAR-T therapy. The patient had a complete response to tisagenlecleucel, did not develop cytokine release syndrome, or worsening of SARS-CoV-2 during therapy. The patient had evidence of ongoing persistence of IgG antibody responses to spike and nucleocapsid after LD followed by tisagenlecleucel despite the B-cell aplasia. Further we were able to detect SARS-CoV-2 specific T-cells recognizing multiple viral structural proteins for several months following CAR-T. The T-cell response was polyfunctional and predominantly CD4 restricted. This data has important implications for the understanding of SARS-CoV-2 immunity in patients with impaired immune systems and the potential application of SARS-CoV-2-specific T-cell therapeutics to treat patients with blood cancers who receive B cell depleting therapy.

Antibody responses to the SARS-CoV-2 vaccine in individuals with various inborn errors of immunity.

BACKGROUND: SARS-CoV-2 vaccination is recommended in patients with inborn errors of immunity (IEIs); however, little is known about immunogenicity and safety in these patients. OBJECTIVE: We sought to evaluate the impact of genetic diagnosis, age, and treatment on antibody response to COVID-19 vaccine and related adverse events in a cohort of patients with IEIs. METHODS: Plasma was collected from 22 health care worker controls, 81 patients with IEIs, and 2 patients with thymoma; the plasma was collected before immunization, 1 to 6 days before the second dose of mRNA vaccine, and at a median of 30 days after completion of the immunization schedule with either mRNA vaccine or a single dose of Johnson & Johnson's Janssen vaccine. Anti-spike (anti-S) and anti-nucleocapsid antibody titers were measured by using a luciferase immunoprecipitation systems method. Information on T- and B-cell counts and use of immunosuppressive drugs was extracted from medical records, and information on vaccine-associated adverse events was collected after each dose. RESULTS: Anti-S antibodies were detected in 27 of 46 patients (58.7%) after 1 dose of mRNA vaccine and in 63 of 74 fully immunized patients (85.1%). A lower rate of seroconversion (7 of 11 [63.6%]) was observed in patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy. Previous use of rituximab and baseline counts of less than 1000 CD3+ T cells/mL and less than 100 CD19+ B cells/mL were associated with lower anti-S IgG levels. No significant adverse events were reported. CONCLUSION: Vaccinating patients with IEIs is safe, but immunogenicity is affected by certain therapies and gene defects. These data may guide the counseling of patients with IEIs regarding prevention of SARS-CoV-2 infection and the need for subsequent boosts.

Robust Antibody and T Cell Responses to SARS-CoV-2 in Patients with Antibody Deficiency.

Immunocompromised patients, including those with inborn errors of immunity (IEI), may be at increased risk for severe or prolonged infections with SARS-CoV-2 (Zhu et al. N Engl J Med. 382:727-33, 2020; Guan et al. 2020; Minotti et al. J Infect. 81:e61-6, 2020). While antibody and T cell responses to SARS-CoV-2 structural proteins are well described in healthy convalescent donors, adaptive humoral and cellular immunity has not yet been characterized in patients with antibody deficiency (Grifoni et al. Cell. 181:1489-1501 e1415, 2020; Burbelo et al. 2020; Long et al. Nat Med. 26:845-8, 2020; Braun et al. 2020). Herein, we describe the clinical course, antibody, and T cell responses to SARS-CoV-2 structural proteins in a cohort of adult and pediatric patients with antibody deficiencies (n = 5) and controls (related and unrelated) infected with SARS-CoV-2. Five patients within the same family (3 with antibody deficiency, 2 immunocompetent controls) showed antibody responses to nucleocapsid and spike proteins, as well as SARS-CoV-2 specific T cell immunity at days 65-84 from onset of symptoms. No significant difference was identified between immunocompromised patients and controls. Two additional unrelated, adult patients with common variable immune deficiency were assessed. One did not show antibody response, but both demonstrated SARS-CoV-2-specific T cell immunity when evaluated 33 and 76 days, respectively, following SARS-CoV-2 diagnosis. This report is the first to show robust T cell activity and humoral immunity against SARS-CoV-2 structural proteins in some patients with antibody deficiency. Given the reliance on spike protein in most candidate vaccines (Folegatti et al. Lancet. 396:467-78, 2020; Jackson et al. N Engl J Med. 383:1920-31, 2020), the responses are encouraging. Additional studies will be needed to further define the timing of onset of immunity, longevity of the immune response, and variability of response in immunocompromised patients.

Infections in Infants with SCID: Isolation, Infection Screening, and Prophylaxis in PIDTC Centers.

PURPOSE: The Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children with severe combined immunodeficiency (SCID) in a prospective natural history study of hematopoietic stem cell transplant (HSCT) outcomes over the last decade. Despite newborn screening (NBS) for SCID, infections occurred prior to HSCT. This study's objectives were to define the types and timing of infection prior to HSCT in patients diagnosed via NBS or by family history (FH) and to understand the breadth of strategies employed at PIDTC centers for infection prevention. METHODS: We analyzed retrospective data on infections and pre-transplant management in patients with SCID diagnosed by NBS and/or FH and treated with HSCT between 2010 and 2014. PIDTC centers were surveyed in 2018 to understand their practices and protocols for pre-HSCT management. RESULTS: Infections were more common in patients diagnosed via NBS (55%) versus those diagnosed via FH (19%) (p = 0.012). Outpatient versus inpatient management did not impact infections (47% vs 35%, respectively; p = 0.423). There was no consensus among PIDTC survey respondents as to the best setting (inpatient vs outpatient) for pre-HSCT management. While isolation practices varied, immunoglobulin replacement and antimicrobial prophylaxis were more uniformly implemented. CONCLUSION: Infants with SCID diagnosed due to FH had lower rates of infection and proceeded to HSCT more quickly than did those diagnosed via NBS. Pre-HSCT management practices were highly variable between centers, although uses of prophylaxis and immunoglobulin support were more consistent. This study demonstrates a critical need for development of evidence-based guidelines for the pre-HSCT management of infants with SCID following an abnormal NBS. TRIAL REGISTRATION: NCT01186913.

Identification of new cytokine combinations for antigen-specific T-cell therapy products via a high-throughput multi-parameter assay.

Infusion of viral-specific T cells (VSTs) is an effective treatment for viral infection after stem cell transplant. Current manufacturing approaches are rapid, but growth conditions can still be further improved. To optimize VST cell products, the authors designed a high-throughput flow cytometry-based assay using 40 cytokine combinations in a 96-well plate to fully characterize T-cell viability, function, growth and differentiation. Peripheral blood mononuclear cells (PBMCs) from six consenting donors were seeded at 100 000 cells per well with pools of cytomegalovirus peptides from IE1 and pp65 and combinations of IL-15, IL-6, IL-21, interferon alpha, IL-12, IL-18, IL-4 and IL-7. Ten-day cultures were tested by 13-color flow cytometry to evaluate viable cell count, lymphocyte phenotype, memory markers and interferon gamma (IFNγ) and tumor necrosis factor alpha (TNFα) expression. Combinations of IL-15/IL-6 and IL-4/IL-7 were optimal for the expansion of viral-specific CD3+ T cells, (18-fold and 14-fold, respectively, compared with unstimulated controls). CD8+ T cells expanded 24-fold in IL-15/IL-6 and 9-fold in IL-4/IL-7 cultures (P < 0.0001). CD4+ T cells expanded 27-fold in IL-4/IL-7 and 15-fold in IL-15/IL-6 (P < 0.0001). CD45RO+ CCR7- effector memory (CD45RO+ CCR7- CD3+), central memory (CD45RO+ CCR7+ CD3+), terminal effector (CD45RO- CCR7- CD3+), and naive (CD45RO- CCR7+ CD3+). T cells were the preponderant cells (76.8% and 72.3% in IL-15/IL-6 and IL-15/IL-7 cultures, respectively). Cells cultured in both cytokine conditions were potent, with 19.4% of CD3+ cells cultured in IL-15/IL-6 producing IFNγ (7.6% producing both TNFα and IFNγ) and 18.5% of CD3+ cells grown in IL-4/IL-7 producing IFNγ (9% producing both TNFα and IFNγ). This study shows the utility of this single-plate assay to rapidly identify optimal growth conditions for VST manufacture using only 107 PBMCs.

Identification of novel HLA-restricted preferentially expressed antigen in melanoma peptides to facilitate off-the-shelf tumor-associated antigen-specific T-cell therapies.

BACKGROUND AIMS: Preferentially expressed antigen in melanoma (PRAME) is a cancer/testis antigen that is overexpressed in many human malignancies and poorly expressed or absent in healthy tissues, making it a good target for anti-cancer immunotherapy. Development of an effective off-the-shelf adoptive T-cell therapy for patients with relapsed or refractory solid tumors and hematological malignancies expressing PRAME antigen requires the identification of major histocompatibility complex (MHC) class I and II PRAME antigens recognized by the tumor-associated antigen (TAA) T-cell product. The authors therefore set out to extend the repertoire of HLA-restricted PRAME peptide epitopes beyond the few already characterized. METHODS: Peptide libraries of 125 overlapping 15-mer peptides spanning the entire PRAME protein sequence were used to identify HLA class I- and II-restricted epitopes. The authors also determined the HLA restriction of the identified epitopes. RESULTS: PRAME-specific T-cell products were successfully generated from peripheral blood mononuclear cells of 12 healthy donors. Ex vivo-expanded T cells were polyclonal, consisting of both CD4+ and CD8+ T cells, which elicited anti-tumor activity in vitro. Nine MHC class I-restricted PRAME epitopes were identified (seven novel and two previously described). The authors also characterized 16 individual 15-mer peptide sequences confirmed as CD4-restricted epitopes. CONCLUSIONS: TAA T cells derived from healthy donors recognize a broad range of CD4+ and CD8+ HLA-restricted PRAME epitopes, which could be used to select suitable donors for generating off-the-shelf TAA-specific T cells.