Intra-tumoral and peripheral blood TIGIT and PD-1 as immune biomarkers in nodular lymphocyte predominant Hodgkin lymphoma.

In classical Hodgkin lymphoma (cHL), responsiveness to immune-checkpoint blockade (ICB) is associated with specific tumor microenvironment (TME) and peripheral blood features. The role of ICB in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is not established. To gain insights into its potential in NLPHL, we compared TME and peripheral blood signatures between HLs using an integrative multiomic analysis. A discovery/validation approach in 121 NLPHL and 114 cHL patients highlighted >2-fold enrichment in programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) gene expression for NLPHL versus cHL. Multiplex imaging showed marked increase in intra-tumoral protein expression of PD-1+ (and/or TIGIT+) CD4+ T-cells and PD-1+CD8+ T-cells in NLPHL compared to cHL. This included T-cells that rosetted with lymphocyte predominant (LP) and Hodgkin Reed-Sternberg (HRS) cells. In NLPHL, intra-tumoral PD-1+CD4+ T-cells frequently expressed TCF-1, a marker of heightened T-cell response to ICB. The peripheral blood signatures between HLs were also distinct, with higher levels of PD-1+TIGIT+ in TH1, TH2, and regulatory CD4+ T-cells in NLPHL versus cHL. Circulating PD-1+CD4+ had high levels of TCF-1. Notably, in both lymphomas, highly expanded populations of clonal TIGIT+PD-1+CD4+ and TIGIT+PD-1+CD8+ T-cells in the blood were also present in the TME, indicating that immune-checkpoint expressing T-cells circulated between intra-tumoral and blood compartments. In in vitro assays, ICB was capable of reducing rosette formation around LP and HRS cells, suggesting that disruption of rosetting may be a mechanism of action of ICB in HL. Overall, results indicate that further evaluation of ICB is warranted in NLPHL.

Investigation of product-derived lymphoma following infusion of piggyBac-modified CD19 chimeric antigen receptor T cells.

We performed a phase 1 clinical trial to evaluate outcomes in patients receiving donor-derived CD19-specific chimeric antigen receptor (CAR) T cells for B-cell malignancy that relapsed or persisted after matched related allogeneic hemopoietic stem cell transplant. To overcome the cost and transgene-capacity limitations of traditional viral vectors, CAR T cells were produced using the piggyBac transposon system of genetic modification. Following CAR T-cell infusion, 1 patient developed a gradually enlarging retroperitoneal tumor due to a CAR-expressing CD4+ T-cell lymphoma. Screening of other patients led to the detection, in an asymptomatic patient, of a second CAR T-cell tumor in thoracic para-aortic lymph nodes. Analysis of the first lymphoma showed a high transgene copy number, but no insertion into typical oncogenes. There were also structural changes such as altered genomic copy number and point mutations unrelated to the insertion sites. Transcriptome analysis showed transgene promoter-driven upregulation of transcription of surrounding regions despite insulator sequences surrounding the transgene. However, marked global changes in transcription predominantly correlated with gene copy number rather than insertion sites. In both patients, the CAR T-cell-derived lymphoma progressed and 1 patient died. We describe the first 2 cases of malignant lymphoma derived from CAR gene-modified T cells. Although CAR T cells have an enviable record of safety to date, our results emphasize the need for caution and regular follow-up of CAR T recipients, especially when novel methods of gene transfer are used to create genetically modified immune therapies. This trial was registered at www.anzctr.org.au as ACTRN12617001579381.

Combining CD34+ stem cell selection with prophylactic pathogen and leukemia directed T-cell immunotherapy to simultaneously reduce graft versus host disease, infection, and leukemia recurrence after allogeneic stem cell transplant.

We designed a trial to simultaneously address the problems of graft versus host disease (GVHD), infection, and recurrence of malignancy after allogeneic stem cell transplantation. CD34+ stem cell isolation was used to minimize the development of acute and chronic GVHD. Two prophylactic infusions, one combining donor-derived cytomegalovirus, Epstein-Barr virus, and Aspergillus fumigatus specific T-cells and the other comprising donor-derived CD19 directed chimeric antigen receptor (CAR) bearing T-cells, were given 21-28 days after transplant. Two patients were transplanted for acute lymphoblastic leukemia from HLA identical siblings using standard doses of cyclophosphamide and total body irradiation without antilymphocyte globulin. Patients received no post-transplant immune suppression and were given no pre-CAR T-cell lymphodepletion. Neutrophil and platelet engraftment was prompt. Following adoptive T-cell infusions, there was rapid appearance of antigen-experienced CD8+ and to a lesser extent CD4+ T-cells. Tetramer-positive T-cells targeting CMV and EBV appeared rapidly after T-cell infusion and persisted for at least 1 year. CAR T-cell expansion occurred and persisted for up to 3 months. T-cell receptor tracking confirmed the presence of product-derived T-cell clones in blood targeting all three pathogens. Both patients are alive over 3 years post-transplant without evidence of GVHD or disease recurrence. Combining robust donor T-cell depletion with directed T-cell adoptive immunotherapy targeting infectious and malignant antigens permits independent modulation of GVHD, infection, and disease recurrence. The combination may separate GVHD from the graft versus tumor effect, accelerate immune reconstitution, and improve transplant tolerability.

Long-term outcomes of corticosteroid graft versus host disease prophylaxis in peripheral blood allogeneic haemopoietic stem cell transplant: a comparative cohort analysis.

BACKGROUND: Corticosteroids (CSs) have previously been incorporated into graft versus host disease (GVHD) prophylaxis regimens for bone marrow (BM) and haemopoietic stem cell transplant (HSCT). AIMS: To assess the impact of prophylactic CS in HSCT using peripheral blood (PB) stem cells. METHODS: Patients were identified from three HSCT centres receiving a first PB-HSCT between January 2011 and December 2015 from a fully human leukocyte antigen (HLA)-matched sibling or unrelated donor for acute myeloid leukaemia or acute lymphoblastic leukaemia. To enable meaningful comparison, patients were divided into two cohorts. RESULTS: Cohort 1 included only myeloablative-matched sibling HSCT, where the only variation in GVHD prophylaxis was the addition of CS. In these 48 patients, there were no differences in GVHD, relapse, non-relapse mortality, overall survival or GVHD-relapse-free-survival (GRFS) at 4 years after transplant. Cohort 2 included the remaining HSCT recipients, where one group received CS-prophylaxis and the non-CS group received an antimetabolite, ciclosporin and anti-T-lymphocyte globulin. In these 147 patients, those receiving CS-prophylaxis experienced higher rates of chronic GVHD (71% vs 18.1%, P < 0.001) and lower rates of relapse (14.9% vs 33.9%, P = 0.02). Those receiving CS-prophylaxis had a lower 4-year GRFS (15.7% vs 40.3%, P = 0.002). CONCLUSIONS: There does not appear to be a role for adding CS to standard GVHD prophylaxis regimens in PB-HSCT.

Australia and New Zealand Transplant and Cellular Therapies (ANZTCT) position statement: COVID-19 management in patients with haemopoietic stem cell transplant and chimeric antigen receptor T cell.

Patients with post-haemopoietic stem cell transplant or chimeric antigen receptor T -cell (CAR-T) therapy face a significant risk of morbidity and mortality from coronavirus disease 2019 because of their immunosuppressed state. As case numbers in Australia and New Zealand continue to rise, guidance on management in this high-risk population is needed. Whilst we have learned much from international colleagues who faced high infection rates early in the pandemic, guidance relevant to local health system structures, medication availability and emerging therapies is essential to equip physicians to manage our patients optimally.

Identification of SARS-CoV-2 Nucleocapsid and Spike T-Cell Epitopes for Assessing T-Cell Immunity.

Developing optimal T-cell response assays to severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is critical for measuring the duration of immunity to this disease and assessing the efficacy of vaccine candidates. These assays need to target conserved regions of SARS-CoV-2 global variants and avoid cross-reactivity to seasonal human coronaviruses. To contribute to this effort, we employed an in silico immunoinformatics analysis pipeline to identify immunogenic peptides resulting from conserved and highly networked regions with topological importance from the SARS-CoV-2 nucleocapsid and spike proteins. A total of 57 highly networked T-cell epitopes that are conserved across geographic viral variants were identified from these viral proteins, with a binding potential to diverse HLA alleles and 80 to 100% global population coverage. Importantly, 18 of these T-cell epitope derived peptides had limited homology to seasonal human coronaviruses making them promising candidates for SARS-CoV-2-specific T-cell immunity assays. Moreover, two of the NC-derived peptides elicited effector/polyfunctional responses of CD8+ T cells derived from SARS-CoV-2 convalescent patients.IMPORTANCE The development of specific and validated immunologic tools is critical for understanding the level and duration of the cellular response induced by SARS-CoV-2 infection and/or vaccines against this novel coronavirus disease. To contribute to this effort, we employed an immunoinformatics analysis pipeline to define 57 SARS-CoV-2 immunogenic peptides within topologically important regions of the nucleocapsid (NC) and spike (S) proteins that will be effective for detecting cellular immune responses in 80 to 100% of the global population. Our immunoinformatics analysis revealed that 18 of these peptides had limited homology to circulating seasonal human coronaviruses and therefore are promising candidates for distinguishing SARS-CoV-2-specific immune responses from pre-existing coronavirus immunity. Importantly, CD8+ T cells derived from SARS-CoV-2 survivors exhibited polyfunctional effector responses to two novel NC-derived peptides identified as HLA-binders. These studies provide a proof of concept that our immunoinformatics analysis pipeline identifies novel immunogens which can elicit polyfunctional SARS-CoV-2-specific T-cell responses.

Successful treatment of Epstein-Barr virus-associated primary central nervous system lymphoma due to post-transplantation lymphoproliferative disorder, with ibrutinib and third-party Epstein-Barr virus-specific T cells.

Primary central nervous system lymphoma (PCNSL) occurring following organ transplantation (post-transplantation lymphoproliferative disorder [PTLD]) is a highly aggressive non-Hodgkin lymphoma. It is typically treated with high-dose methotrexate-based regimens. Outcomes are dismal and clinical trials are lacking. It is almost always Epstein-Barr virus (EBV) associated. Two patients (CA1-2) presented with EBV-associated PCNSL after renal transplant. CA1 was on hemodialysis and had prior disseminated cryptococcus and pseudomonas bronchiectasis, precluding treatment with methotrexate. CA2 was refractory to methotrexate. Both were treated off-label with the first-generation Bruton's tyrosine kinase inhibitor ibrutinib for 12 months. Cerebrospinal fluid penetration at therapeutic levels was confirmed in CA1 despite hemodialysis. Both patients entered remission by 2 months. Sequencing confirmed absence of genetic aberrations in human leukocyte antigen (HLA) class I/II and antigen-presentation/processing genes, indicating retention of the ability to present EBV-antigens. Between Weeks 10 and 13, they received third-party EBV-specific T cells for consolidation with no adverse effects. They remain in remission ≥34 months since therapy began. The strength of these findings led to an ongoing phase I study (ACTRN12618001541291).

Beyond antivirals: virus-specific T-cell immunotherapy for BK virus haemorrhagic cystitis and JC virus progressive multifocal leukoencephalopathy.

PURPOSE OF REVIEW: The clinical manifestations of the polyomaviruses BK and JC in immunocompromised patients include BK virus (BKV) induced haemorrhagic cystitis and nephropathy, and JC virus (JCV) associated progressive multifocal leukoencephalopathy (PML) and are typically a consequence of impaired adaptive immunity in the host. To date, little clinical success has been achieved with antiviral agents or other drug therapies to treat these conditions. Here we review the methods and outcomes of the most recent clinical studies utilising adoptive immunotherapy with BK and/or JC virus-specific T-cells (VST) as either prophylaxis or treatment alternatives. RECENT FINDINGS: In the last 12-18 months, several clinical trials have been published in the post-haemopoietic stem cell transplant (HSCT) setting showing good clinical success with the use of VST for treatment of BK viremia ± haemorrhagic cystitis. Between 82 and 100% clinical response has been observed in haemorrhagic cystitis using either third-party or donor-derived VST. The therapy was well tolerated with few cases of graft versus host disease in HSCT recipients, but immune mediated renal allograft loss was observed in one renal transplant recipient. Studies using BKV/JCV VST to treat PML are hindered by few patients who are sufficiently stable to receive VST. In a condition that otherwise carries such poor prognosis, VST were associated with clearance of JC virus, clinical and radiological improvement in some patients. Immune reconstitution inflammatory syndrome was a noted adverse event. SUMMARY: Restoration of BK and JC virus immunity using VST immunotherapy has shown good clinical outcomes in BKV associated infections. Further evaluation with the administration of VST earlier in the course of disease is warranted for the treatment of BKV associated nephropathy in renal allograft and in JCV PML. In both indications, larger cohorts and standardisation of dosing and outcome measures would be of benefit.

Successful treatment of CMV, EBV, and adenovirus tissue infection following HLA-mismatched allogeneic stem cell transplant using infusion of third-party T cells from multiple donors in addition to antivirals, rituximab, and surgery.

Viral infections, principally cytomegalovirus, Epstein Barr virus (EBV) and adenovirus, are a leading cause of morbidity and mortality after allogeneic stem cell transplantation. The use of systemic antivirals is limited by limited efficacy and organ toxicities. Inability to clear infection is exacerbated by transplant-related immunosuppression and prophylaxis or treatment of acute graft versus host disease. We report the first patient to clear three serious viral infections after stem cell transplant using third-party donor partially human leukocyte antigen (HLA) matched virus-specific cytotoxic T cells. The patient, a 53 year old female with transplanted for relapsed leukemia, with severe graft versus host disease received five T cell infusions from three separate donors that ultimately cleared serious systemic infections with cytomegalovirus and adenovirus, and an EBV-driven lymphoma. Systemic antivirals had resulted in failed clinical responses. Use of repeated infusions of partially HLA matched virus-specific T cells from banks containing cryopreserved cells should be strongly considered in transplant recipients with single or multiple refractory viral infections.

Unrelated Donor Transplant Recipients Given Thymoglobuline Have Superior GRFS When Compared to Matched Related Donor Recipients Undergoing Transplantation without ATG.

Recipients of allogeneic hematopoietic stem cell transplantation (HSCT) from unrelated donors (URDs) and mismatched related donors (MMRDs) typically have a higher incidence of acute and chronic graft-versus-host disease (GVHD) compared with matched related donors (MRDs). Anti-T-cell globulins (ATGs) are often used to reduce GVHD in these recipients. We report the outcomes of 211 adult peripheral blood stem cell transplant recipients with myeloid malignancies who received a standardized transplant protocol, in which ATG (Thymoglobuline 4.5 mg/kg) was administered to recipients of URD and MMRD (n = 147) but not MRD (n = 64) transplant. For all patients, incidence of acute GVHD grades 2 to 4 was 21.4%, and chronic GVHD was 35.0%. Two-year overall survival was 63.2% (95% confidence interval, 55.8% to 71.5%), relapse-free survival was 55.3% (47.4% to 64.6%), and GVHD-free, relapse-free survival (GRFS) was 30.7% (23.2% to 40.8%). There were no differences between recipients of MRDs and other donors in relapse, nonrelapse mortality, and overall and relapse-free survival. However, compared with MRD, recipients from URDs and MMRDs had reduced moderate to severe chronic GVHD (10.4% versus 30.1%, P= .002), less chronic GVHD requiring systemic therapy (19.4% versus 38.9%, P = .006), and superior 2-year GRFS (35.5% versus 20.0%, P = .003). In this retrospective review of nonrandomized transplant groups, outcomes of HSCT performed using an URD with ATG during conditioning were superior to transplant from an MRD without ATG. The addition of Thymoglobuline to conditioning in HSCT from MRD should be further examined in prospective trials.

Restriction of Human Cytomegalovirus Infection by Galectin-9.

Human cytomegalovirus (HCMV) is a ubiquitous human herpesvirus. While HCMV infection is generally asymptomatic in the immunocompetent, it can have devastating consequences in those with compromised or underdeveloped immune systems, including transplant recipients and neonates. Galectins are a widely expressed protein family that have been demonstrated to modulate both antiviral immunity and regulate direct host-virus interactions. The potential for galectins to directly modulate HCMV infection has not previously been studied, and our results reveal that galectin-9 (Gal-9) can potently inhibit HCMV infection. Gal-9-mediated inhibition of HCMV was dependent upon its carbohydrate recognition domains and thus dependent on glycan interactions. Temperature shift studies revealed that Gal-9 specific inhibition was mediated primarily at the level of virus-cell fusion and not binding. Additionally, we found that during reactivation of HCMV in hematopoietic stem cell transplant (HSCT) patients soluble Gal-9 is upregulated. This study provides the first evidence for Gal-9 functioning as a potent antiviral defense effector molecule against HCMV infection and identifies it as a potential clinical candidate to restrict HCMV infections.IMPORTANCE Human cytomegalovirus (HCMV) continues to cause serious and often life-threatening disease in those with impaired or underdeveloped immune systems. This virus is able to infect and replicate in a wide range of human cell types, which enables the virus to spread to other individuals in a number of settings. Current antiviral drugs are associated with a significant toxicity profile, and there is no vaccine; these factors highlight a need to identify additional targets for the development of anti-HCMV therapies. We demonstrate for the first time that secretion of a member of the galectin family of proteins, galectin-9 (Gal-9), is upregulated during natural HCMV-reactivated infection and that this soluble cellular protein possesses a potent capacity to block HCMV infection by inhibiting virus entry into the host cell. Our findings support the possibility of harnessing the antiviral properties of Gal-9 to prevent HCMV infection and disease.

Managing haematology and oncology patients during the COVID-19 pandemic: interim consensus guidance.

INTRODUCTION: A pandemic coronavirus, SARS-CoV-2, causes COVID-19, a potentially life-threatening respiratory disease. Patients with cancer may have compromised immunity due to their malignancy and/or treatment, and may be at elevated risk of severe COVID-19. Community transmission of COVID-19 could overwhelm health care services, compromising delivery of cancer care. This interim consensus guidance provides advice for clinicians managing patients with cancer during the pandemic. MAIN RECOMMENDATIONS: During the COVID-19 pandemic: In patients with cancer with fever and/or respiratory symptoms, consider causes in addition to COVID-19, including other infections and therapy-related pneumonitis. For suspected or confirmed COVID-19, discuss temporary cessation of cancer therapy with a relevant specialist. Provide information on COVID-19 for patients and carers. Adopt measures within cancer centres to reduce risk of nosocomial SARS-CoV-2 acquisition; support population-wide social distancing; reduce demand on acute services; ensure adequate staffing; and provide culturally safe care. Measures should be equitable, transparent and proportionate to the COVID-19 threat. Consider the risks and benefits of modifying cancer therapies due to COVID-19. Communicate treatment modifications, and review once health service capacity allows. Consider potential impacts of COVID-19 on the blood supply and availability of stem cell donors. Discuss and document goals of care, and involve palliative care services in contingency planning. CHANGES IN MANAGEMENT AS A RESULT OF THIS STATEMENT: This interim consensus guidance provides a framework for clinicians managing patients with cancer during the COVID-19 pandemic. In view of the rapidly changing situation, clinicians must also monitor national, state, local and institutional policies, which will take precedence. ENDORSED BY: Australasian Leukaemia and Lymphoma Group; Australasian Lung Cancer Trials Group; Australian and New Zealand Children's Haematology/Oncology Group; Australia and New Zealand Society of Palliative Medicine; Australasian Society for Infectious Diseases; Bone Marrow Transplantation Society of Australia and New Zealand; Cancer Council Australia; Cancer Nurses Society of Australia; Cancer Society of New Zealand; Clinical Oncology Society of Australia; Haematology Society of Australia and New Zealand; National Centre for Infections in Cancer; New Zealand Cancer Control Agency; New Zealand Society for Oncology; and Palliative Care Australia.

Pre- and post-bone marrow harvest anaemia is associated with lower CD34+ stem cell collection, high harvest volume and female gender.

BACKGROUND: Donor safety is paramount when performing bone marrow stem cell harvest. The incidence of full blood count (FBC) abnormalities among donors and variables associated with anaemia after marrow harvest are not well established. AIMS: To describe the frequency of FBC abnormalities prior to bone marrow stem cell harvest and to identify variables associated with post harvest anaemia. METHODS: Outcomes of 80 consecutive adult marrow harvests performed at our centre were analysed retrospectively. RESULTS: FBC abnormalities were present in 28% of donors prior to marrow harvest with normocytic anaemia the most common abnormality in 13%. Reduced donor haemoglobin (Hb) was independently correlated with lower CD34+ cell count per kg of recipient body weight. Anaemia (Hb < 100 g/L) was seen in 20% of donors after harvest with median decrease in Hb of 19 g/L. Variables independently associated with anaemia after harvest included donor to recipient weight ratio (P = 0.011), high collection volume (P = 0.044) and female gender (P = 0.023). Total nucleated cell and CD34 concentration in the final collected product were associated with the inverse of harvested marrow volume (P < 0.001). CONCLUSIONS: Pre-harvest anaemia should be corrected where possible particularly in female donors. Marrow collection volume should be minimised to reduce post-harvest anaemia, optimise CD34+ cell number and improve nucleated and stem cell concentrations in the harvest product.

Establishment and Operation of a Third-Party Virus-Specific T Cell Bank within an Allogeneic Stem Cell Transplant Program.

Hematopoietic stem cell transplantation (HSCT) donor-generated virus-specific T cells (VSTs) can provide effective treatment for viral infection post-HSCT but are not readily accessible to all patients. Off-the-shelf cryopreserved VSTs suitable for treatment of multiple patients are an attractive alternative. We generated a bank of 17 cytomegalovirus (CMV)-, 14 Epstein-Barr virus (EBV)-, and 15 adenovirus (AdV)-specific T cell products from 30 third-party donors. Donors were selected for expression of 6 core HLA antigens expressed at high frequency in the local transplant population. T cells were generated by co-culturing venous blood or mobilized hematopoietic stem cell (HSC)-derived mononuclear cells with monocyte-derived dendritic cells pulsed with overlapping peptides covering CMV pp65, AdV5 hexon, or EBV BZLF1/LMP2A/EBNA1 proteins. Addition of a CD14+ selection step instead of plate adherence to isolate monocytes before culture initiation significantly improved expansion in cultures from HSC material. Phenotyping showed the CD8+ subset to have significantly higher numbers of terminal effector T cells (CD45RA+62L-) and lower numbers of effector memory T cells (CD45RA-62L-) when compared with the CD4+ subset. Increased expression of the immunoinhibitory markers PD-1 and TIM-3 was noted on CD4+ but not CD8+ cells when compared with the control group. VST showed antiviral activity restricted through a variety of common HLAs, and modelling suggested a suitably HLA-matched product would be available for >90% of HSCT patients. Only a small number of carefully selected third-party donors are required to generate a VST bank of broad coverage, indicating the feasibility of local banking integrated into existing allogeneic HSCT programs.

Adjuvant Peptide Pulsed Dendritic Cell Vaccination in Addition to T Cell Adoptive Immunotherapy for Cytomegalovirus Infection in Allogeneic Hematopoietic Stem Cell Transplantation Recipients.

Adoptive cellular immunotherapy has been shown to be effective in the management of cytomegalovirus (CMV) reactivation and disease. Whether adjuvant dendritic cell (DC) vaccination will provide additional benefit in prophylaxis or treatment of CMV in hematoietic cell transplantation (HSCT) recipients is unknown. In this study, we administered prophylactic CMV-peptide specific T cell infusions, followed by 2 doses of intradermal CMV peptide-pulsed DC vaccine, to 4 HSCT recipients. There were no immediate adverse events associated with T cell infusion or DC vaccinations. One of the 4 patients developed grade III acute gut graft-versus-host disease. Immune reconstitution against CMV was detected in all 4 patients. Patients receiving CMV peptide-specific T cells and DC vaccination had peak immune reconstitution at least 10 days after the second DC vaccination. In summary, combining DC vaccine with T cell infusion appears feasible, although further study is required to ascertain its safety and efficacy in augmenting the effects of infusing donor-derived CMV-specific T cells.

Ultra-Sensitive Droplet Digital PCR for the Assessment of Microchimerism in Cellular Therapies.

Current techniques to assess chimerism after hematopoietic stem cell transplantation (HSCT) are limited in both sensitivity and precision. These drawbacks are problematic in the context of cellular therapies that frequently result in microchimerism (donor chimerism <1%). We have developed a highly sensitive droplet digital PCR (ddPCR) assay using commercially available regents with good performance throughout the range of clinically relevant chimerism measurements, including microchimerism. We tested the assay using spiked samples of known donor-recipient ratios and in clinical samples from HSCT recipients and patients enrolled on clinical trials of microtransplantation and third-party virus-specific T cells (VSTs). The levels of detection and quantification of the assay were .008% and .023%, with high levels of precision with samples of DNA content ranging from 1 to 300 ng DNA. From the panel of 29 insertion-deletion probes multiple informative markers were found for each of 43 HSCT donor-recipient pairs. In the case of third-party cellular therapies in which there were 3 DNA contributors (recipient, HSCT donor, and T-cell donor), a marker to detect the cellular product in a background of recipient and donor cells was available for 11 of 12 cases (92%). Chimerism by ddPCR was able to quantify chimerism in HSCT recipients and comparison against standard STR analysis in 8 HSCT patients demonstrated similar results, with the advantage of fast turnaround time. Persistence of donor microchimerism in patients undergoing microtransplantation for acute myeloid leukemia was detectable for up to 57 days in peripheral blood and bone marrow. The presence of microtransplant product DNA in bone marrow T cells after cell sorting was seen in the 1 patient tested. In patients receiving third-party VSTs for treatment of refractory viral infections, VST donor DNA was detected at low levels in 7 of 9 cases. ddPCR offers advantages over currently available methods for assessment of chimerism in standard HSCT and cellular therapies.

Rescue haploidentical peripheral blood stem cell transplantation for engraftment failure: a single-centre case series.

Graft failure affects approximately 5% of allogeneic stem cell transplants, with a poor prognosis. Salvage second allogeneic stem cell transplantation (alloSCT2) is limited by high rates of transplant-related mortality from infection and graft-versus-host disease. We report on five adult patients receiving rescue alloSCT2 using haploidentical peripheral blood stem cells. All patients achieved neutrophil engraftment, two subsequently died from sepsis and disease relapse, respectively. Three patients remain alive up to 2 years post-transplant. We suggest consideration of haploidentical alloSCT2 for patients with graft failure.

Cellular therapy for multiple pathogen infections after hematopoietic stem cell transplant.

Hematopoietic stem cell transplantation (HSCT) represents the only crative treatment option for many hematological conditions but results in a profound T-cell deficiency in the post-HSCT period. Infections account for a significant proportion of non-relapse morbidity and mortality, and infections with multiple organisms either simultaneously or at different times after transplant are common. Adoptive cellular therapy (ACT) with prophylactic or therapeutic infusion of donor derived or third-party, pathogen-specific T-cells represents a novel methodology to rapidly reconstitute T-cell mediated immunity in this context. For cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infection, clear evidence of efficacy with limited toxicity has been observed, with response rates up to 90%. Infusion of third-party, partially human leukocyte antigen-matched pathogen-specific T-cells have also demonstrated remarkable efficacy with responses seen in up to 70% of patients with resistant CMV, EBV and adenoviral infection. This review addresses the nature of post-HSCT immune deficiency, the common infections that occur in the post-HSCT period and how advances in ACT manufacturing methodologies is allowing for wider implementation of T-cell therapies targeting multiple pathogens in HSCT recipients.

Herpes simplex virus type 1 (HSV-1) specific T-cell generation from HLA-A1- and HLA-A2-positive donors for adoptive immunotherapy.

BACKGROUND AIMS: Herpes simplex virus (HSV) reactivation and infection is common in patients undergoing hematopoietic stem cell transplant (HSCT) and requires routine antiviral prophylaxis. Drug-resistant strains are increasingly common, and effective alternative therapy is currently unavailable. We generated and characterized HSV-1-specific T cells for use in adoptive cellular immunotherapy following allogeneic stem cell transplantation. METHODS: Peripheral blood mononuclear cells from HLA-A1 and HLA-A2 HSV-seropositive hereditary hemochromatosis donors were used as the antigen source. Three HLA-A1 and four HLA-A2 specific epitopes were used for stimulation of T cells. Cells were stimulated with antigen-pulsed dendritic cells and cultured for 21 days in medium with interleukin (IL)-2. Cultured cells were phenotyped and tested for cytokine production, proliferation and cytotoxicity. RESULTS: There was a 5.3-fold expansion in total cell numbers over 21 days of culture, with 35% of T cells being CD8 positive. Thirty-five percent, 21% and 5% of CD8 cells secreted interferon-γ, tumor necrosis factor-α and IL-2 upon HSV antigen re-stimulation. More than 50% of antigen-specific T cells secreted multiple cytokines. Cultured T cells proliferated upon antigen re-stimulation and lysed HSV-1 peptide and virus-infected targets. CONCLUSIONS: It is feasible to generate functional HSV-1 specific T cells from the blood of HLA-A1 and HLA-A2 HSV-seropositive donors using specific peptides. The utility of these cells in preventing and treating HSV-1 reactivation in allogeneic HSCT will need to be tested clinically.