Vaccination to improve the persistence of CD19CAR gene-modified T cells in relapsed pediatric acute lymphoblastic leukemia.

Trials with second generation CD19 chimeric antigen receptors (CAR) T-cells report unprecedented responses but are associated with risk of cytokine release syndrome (CRS). Instead, we studied the use of donor Epstein-Barr virus-specific T-cells (EBV CTL) transduced with a first generation CD19CAR, relying on the endogenous T-cell receptor for proliferation. We conducted a multi-center phase I/II study of donor CD19CAR transduced EBV CTL in pediatric acute lymphoblastic leukaemia (ALL). Patients were eligible pre-emptively if they developed molecular relapse (>5 × 10-4) post first stem cell transplant (SCT), or prophylactically post second SCT. An initial cohort showed poor expansion/persistence. We therefore investigated EBV-directed vaccination to enhance expansion/persistence. Eleven patients were treated. No CRS, neurotoxicity or graft versus host disease (GVHD) was observed. At 1 month, 5 patients were in CR (4 continuing, 1 de novo), 1 PR, 3 had stable disease and 3 no response. At a median follow-up of 12 months, 10 of 11 have relapsed, 2 are alive with disease and 1 alive in CR 3 years. Although CD19CAR CTL expansion was poor, persistence was enhanced by vaccination. Median persistence was 0 (range: 0-28) days without vaccination compared to 56 (range: 0-221) days with vaccination (P=0.06). This study demonstrates the feasibility of multi-center studies of CAR T cell therapy and the potential for enhancing persistence with vaccination.

Wide bandwidth fiber-optic ultrasound probe in MOMS technology: Preliminary signal processing results.

An ultrasonic probe consisting of two optical fiber-based miniaturized transducers for wideband ultrasound emission and detection is employed for the characterization of in vitro biological tissues. In the probe, ultrasound generation is obtained by thermoelastic emission from patterned carbon films in Micro-Opto-Mechanical-System (MOMS) devices mounted on the tip of an optical fiber, whereas acousto-optical detection is performed in a similar way by a miniaturized polymeric interferometer. The microprobe presents a wide, flat bandwidth that is a very attractive feature for ultrasonic investigation, especially for tissue characterization. Thanks to the very high ultrasonic frequencies obtained, the probe is able to reveal different details of the object under investigation by analyzing the ultrasonic signal within different frequencies ranges, as shown by specific experiments performed on a patterned cornstarch flour sample in vitro. This is confirmed by measurements executed to determine the lateral resolution of the microprobe at different frequencies of about 70µm at 120MHz. Moreover, measurements performed with the wideband probe in pulsed-echo mode on a histological finding of porcine kidney are presented, on which two different spectral signal processing algorithms are applied. After processing, the ultrasonic spectral features show a peculiar spatial distribution on the sample, which is expected to depend on different ultrasonic backscattering properties of the analyzed tissues.

Gut microbiota and hematopoietic stem cell transplantation: where do we stand?

Advances in biological techniques have potentiated great progresses in understanding the interaction between human beings and the ∼10 to 100 trillion microbes living in their gastrointestinal tract: gut microbiota (GM). In this review, we describe recent emerging data on the role of GM in hematopoietic stem cell transplantation, with a focus on immunomodulatory properties in the immune system recovery and the impact in the development of the main complications, as GvHD and infections.

Gut microbiota trajectory in pediatric patients undergoing hematopoietic SCT.

Acute GvHD (aGvHD) is the main complication of hematopoietic SCT (HSCT) during the treatment of hematological disorders. We carried out the first longitudinal study to follow the gut microbiota trajectory, from both the phylogenetic and functional points of view, in pediatric patients undergoing HSCT. Gut microbiota trajectories and short-chain fatty acid production profiles were followed starting from before HSCT and through the 3-4 months after transplant in children developing and not developing aGvHD. According to our findings, HSCT procedures temporarily cause a structural and functional disruption of the gut microbial ecosystem, describing a trajectory of recovery during the following 100 days. The onset of aGvHD is associated with specific gut microbiota signatures both along the course of gut microbiota reconstruction immediately after transplant and, most interestingly, prior to HSCT. Indeed, in pre-HSCT samples, non-aGvHD patients showed higher abundances of propionate-producing Bacteroidetes, highly adaptable microbiome mutualists that showed to persist during the HSCT-induced ecosystem disruption. Our data indicate that structure and temporal dynamics of the gut microbial ecosystem can be a relevant factor for the success of HSCT and opens the perspective to the manipulation of the pre-HSCT gut microbiota configuration to favor mutualistic persisters with immunomodulatory properties in the gut.

Cell-based strategies to manage leukemia relapse: efficacy and feasibility of immunotherapy approaches.

When treatment fails, the clinical outcome of acute leukemia patients is usually very poor, particularly when failure occurs after transplantation. A second allogeneic stem cell transplant could be envisaged as an effective and feasible salvage option in younger patients having a late relapse and an available donor. Unmanipulated or minimally manipulated donor T cells may also be effective in a minority of patients but the main limit remains the induction of severe graft-versus-host disease. This clinical complication has brought about a huge research effort that led to the development of leukemia-specific T-cell therapy aiming at the direct recognition of leukemia-specific rather than minor histocompatibility antigens. Despite a great scientific interest, the clinical feasibility of such an approach has proven to be quite problematic. To overcome this limitation, more research has moved toward the choice of targeting commonly expressed hematopoietic specific antigens by the genetic modification of unselected T cells. The best example of this is represented by the anti-CD19 chimeric antigen receptor (CD19.CAR) T cells. As a possible alternative to the genetic manipulation of unselected T cells, specific T-cell subpopulations with in vivo favorable homing and long-term survival properties have been genetically modified by CAR molecules. Finally, the use of naturally cytotoxic effector cells such as natural killer and cytokine-induced killer cells has been proposed in several clinical trials. The clinical development of these latter cells could also be further expanded by additional genetic modifications using the CAR technology.

Chimeric antigen receptors against CD33/CD123 antigens efficiently target primary acute myeloid leukemia cells in vivo.

As significant numbers of acute myeloid leukemia (AML) patients are still refractory to conventional therapies or experience relapse, immunotherapy using T cells expressing chimeric antigen receptors (CARs) might represent a valid treatment option. AML cells frequently overexpress the myeloid antigens CD33 and CD123, for which specific CARs can be generated. However, CD33 is also expressed on normal hematopoietic stem/progenitor cells (HSPCs), and its targeting could potentially impair normal hematopoiesis. In contrast, CD123 is widely expressed by AML, while low expression is detected on HSPCs, making it a much more attractive target. In this study we describe the in vivo efficacy and safety of using cytokine-induced killer (CIK) cells genetically modified to express anti-CD33 or anti-CD123 CAR to target AML. We show that both these modified T cells are very efficient in reducing leukemia burden in vivo, but only the anti-CD123 CAR has limited killing on normal HSPCs, thus making it a very attractive immunotherapeutic tool for AML treatment.

In Vitro and In Vivo Antitumor Effect of Anti-CD33 Chimeric Receptor-Expressing EBV-CTL against CD33 Acute Myeloid Leukemia.

Genetic engineering of T cells with chimeric T-cell receptors (CARs) is an attractive strategy to treat malignancies. It extends the range of antigens for adoptive T-cell immunotherapy, and major mechanisms of tumor escape are bypassed. With this strategy we redirected immune responses towards the CD33 antigen to target acute myeloid leukemia. To improve in vivo T-cell persistence, we modified human Epstein Barr Virus-(EBV-) specific cytotoxic T cells with an anti-CD33.CAR. Genetically modified T cells displayed EBV and HLA-unrestricted CD33 bispecificity in vitro. In addition, though showing a myeloablative activity, they did not irreversibly impair the clonogenic potential of normal CD34(+) hematopoietic progenitors. Moreover, after intravenous administration into CD33(+) human acute myeloid leukemia-bearing NOD-SCID mice, anti-CD33-EBV-specific T cells reached the tumor sites exerting antitumor activity in vivo. In conclusion, targeting CD33 by CAR-modified EBV-specific T cells may provide additional therapeutic benefit to AML patients as compared to conventional chemotherapy or transplantation regimens alone.

Polyomavirus JC-targeted T-cell therapy for progressive multiple leukoencephalopathy in a hematopoietic cell transplantation recipient.

Progressive multifocal leukoencephalopathy (PML) associated with polyomavirus JC (JCV) infection has been reported to be usually fatal in allogeneic hematopoietic SCT (HSCT) recipients. We present the case of a 19-year-old HSCT patient diagnosed with JCV-associated PML after prolonged immunosuppression for severe GVHD. No short-term neurological improvement was observed after antiviral treatment and discontinuation of immunosuppressive therapy. Donor-derived JCV Ag-specific CTLs were generated in vitro after stimulation with 15-mer peptides derived from VP1 and large T viral proteins. After adoptive CTL infusion, virus-specific cytotoxic cells were shown in the peripheral blood, JCV-DNA was cleared in the cerebrospinal fluid and the patient showed remarkable improvement. Adoptive T-lymphocyte therapy with JCV-specific CTLs was feasible and had no side effects. This case suggests that adoptive transfer of JCV-targeted CTLs may contribute to restore JCV-specific immune competence and control PML in transplanted patients.

Selective elimination of a chemoresistant side population of B-CLL cells by cytotoxic T lymphocytes in subjects receiving an autologous hCD40L/IL-2 tumor vaccine.

Side-population (SP) analysis identifies precursor cells in normal and malignant tissues. Cells with this phenotype have increased resistance to many cytotoxic agents, and may represent a primary drug-resistant population in malignant diseases. To discover whether drug-resistant malignant SP cells are nonetheless sensitive to immune-mediated killing, we first established the presence of a malignant CD5(+)CD19(+) SP subset in the blood of 18/21 subjects with B-cell chronic lymphocytic leukemia (B-CLL). We examined the fate of these cells in six of these individuals who received autologous human CD40 ligand and interleukin-2 (hCD40L/IL-2) gene-modified tumor cells as part of a tumor vaccine study. Vaccinated patients showed an increase in B-CLL-reactive T cells followed by a corresponding decline in circulating CD5(+)CD19(+) SP cells. T-cell lines and clones generated from vaccinated patients specifically recognized B-CLL SP tumor cells. Elimination of SP cells is likely triggered by their increased expression of target antigens, such as receptor for hyaluronan-mediated motility (RHAMM), after stimulation of the malignant cells by hCD40L, as CD8(+) RHAMM-specific T cells could be detected in the peripheral blood of immunized patients and were associated with the decline in B-CLL SP cells. Hence, malignant B cells with a primary drug-resistant phenotype can be targeted by T- cell-mediated effector activity after immunization of human subjects.

GMP-grade preparation of biomimetic scaffolds with osteo-differentiated autologous mesenchymal stromal cells for the treatment of alveolar bone resorption in periodontal disease.

BACKGROUND: Periodontal disease is a degenerative illness that leads to resorption of the alveolar bone. Mesenchymal stromal cells (MSC) represent a novel tool for the production of biologic constructs for the treatment of degenerative bone diseases. The preparation of MSC differentiated into osteogenic lineage for clinical use requires the fulfillment of strict good manufacturing practice (GMP) procedures. METHODS: MSC were isolated from BM samples and then cultured under GMP conditions. MSC were characterized phenotypically and for their differentiative potential. Cells were seeded onto collagen scaffolds (Gingistat) and induced to differentiate into osteogenic lineages using clinical grade drugs compared with standard osteogenic supplements. Alizarin Red S stain was used to test the deposition of the mineral matrix. Standard microbiologic analysis was performed to verify the product sterility. RESULTS: The resulting MSC were negative for CD33, CD34 and HLA-DR but showed high expression of CD90, CD105 and HLA-ABC (average expressions of 94.3%, 75.8% and 94.2%, respectively). Chondrogenic, osteogenic and adipogenic differentiation potential was demonstrated. The MSC retained their ability to differentiate into osteogenic lineage when seeded onto collagen scaffolds after exposure to a clinical grade medium. Cell numbers and cell viability were adequate for clinical use, and microbiologic assays demonstrated the absence of any contamination. DISCUSSION: In the specific context of a degenerative bone disease with limited involvement of skeletal tissue, the combined use of MSC, exposed to an osteogenic clinical grade medium, and biomimetic biodegradable scaffolds offers the possibility of producing adequate numbers of biologic tissue-engineered cell-based constructs for use in clinical trials.

T cells stimulated by CD40L positive leukemic blasts-pulsed dendritic cells meet optimal functional requirements for adoptive T-cell therapy.

Adoptive T-cell immunotherapy may provide complementary therapy for childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL). In this study, we have analyzed the functional characteristics of anti-BCP-ALL effector T cells generated by co-culturing T lymphocytes and dendritic cells (DC) from allogeneic human stem cell transplantation (HSCT) donors. After 21-day co-culture with DC pulsed with CD40L+ apoptotic BCP-ALL blasts, T cells presented with both effector and central memory phenotype, and showed high and specific cytotoxic activity against leukemic cells (average lysis = 77%), mostly mediated by CD8+ T cells. Noticeably, growth of CD4 T cells was maintained (45% of total cells), which actively produced Th1 cytokines (IFN-gamma, TNF-alpha, IL-2), but not IL-4, IL-5 and IL-10. Anti-BCP-ALL T cells expressed CD49d and CXCR4 (implicated in the recruitment to bone marrow), and CD62L and CCR7 (involved in the migration to lymphoid organs). In accordance with this profile, T cells significantly migrated in response to the chemokines CXCL12 and CCL19. In conclusion, stimulation of T cells with CD40L+BCP-ALL cells-loaded DC not only elicited the generation of potent and specific anti-leukemic cytotoxic effectors, but also the differentiation of specific and functional Th-1 CD4 lymphocytes. These effectors are fully equipped to reach leukemia-infiltrated tissues and have characteristics to support and orchestrate the anti-tumor immune-response.

Rapid and efficient nonviral gene delivery of CD154 to primary chronic lymphocytic leukemia cells.

Interactions between CD40 and CD40 ligand (CD154) are essential in the regulation of both humoral and cellular immune responses. Forced expression of human CD154 in B chronic lymphocytic leukemia (B-CLL) cells can upregulate costimulatory and adhesion molecules and restore antigen-presenting capacity. Unfortunately, B-CLL cells are resistant to direct gene manipulation with most currently available gene transfer systems. In this report, we describe the use of a nonviral, clinical-grade, electroporation-based gene delivery system and a standard plasmid carrying CD154 cDNA, which achieved efficient (64+/-15%) and rapid (within 3 h) transfection of primary B-CLL cells. Consistent results were obtained from multiple human donors. Transfection of CD154 was functional in that it led to upregulated expression of CD80, CD86, ICAM-I and MHC class II (HLA-DR) on the B-CLL cells and induction of allogeneic immune responses in MLR assays. Furthermore, sustained transgene expression was demonstrated in long-term cryopreserved transfected cells. This simple and rapid gene delivery technology has been validated under the current Good Manufacturing Practice conditions, and multiple doses of CD154-expressing cells were prepared for CLL patients from one DNA transfection. Vaccination strategies using autologous tumor cells manipulated ex vivo for patients with B-CLL and perhaps with other hematopoietic malignancies could be practically implemented using this rapid and efficient nonviral gene delivery system.

CD40 ligand-stimulated B cell precursor leukemic cells elicit interferon-gamma production by autologous bone marrow T cells in childhood acute lymphoblastic leukemia.

Childhood B cell precursor acute lymphoblastic leukemia (BCP-ALL) cells, collected from bone marrow (BM) at diagnosis, were cultured, after thawing, on allogeneic human bone marrow stroma (HBMS) for 48 h in the presence of a soluble trimeric CD40 ligand (stCD40L) molecule. HBMS maintained leukemic cells viability in all tested cases (mean viability 85%). Under these culture conditions we noticed upregulation or de novo expression of costimulatory molecules CD40, CD80 (B7-1) and CD86 (B7-2) in 22/22, 15/23 and 21/23 cases, respectively. Upregulation, in terms of fluorescence intensity, was also observed in the expression of MHC I, MHC II, CD54 (ICAM 1) and CD58 (LFA 3) molecules. HBMS alone, although to a lesser extent, was able to induce modulation of these molecules, but not CD80, in a similar proportion of cases. Neither stCD40L nor HBMS induced modulation of CD10 and CD34 molecules. Moreover, in 4/4 tested cases, stCD40L-stimulated ALL cells were able to induce allogeneic T cells proliferation. To evaluate whether leukemia-reactive T cells were detectable in the BM of ALL patients at diagnosis, stCD40L-stimulated ALL cells were co-cultured with autologous T cells (ratio 1:1), isolated from BM at diagnosis, for 4 days and a 24 h ELISPOT assay was applied to detect the presence of interferon-gamma (IFN-gamma)-producing cells. In four of seven cases IFN-gamma-producing cells were detected with frequencies of 1/900, 1/1560, 1/2150 and 1/1575 autologous T cells. These data confirm that stCD40L exposure can activate the antigen-presenting cell (APC) capacity of BCP-ALL cells cultured on HBMS and that ELISPOT assay can be used to measure the frequency of leukemia-reactive autologous T cells in the BM of ALL patients even after short-term culture with stCD40L-stimulated ALL cells.

Intrathecal chemotherapy with antineoplastic agents in children.

Intrathecal chemotherapy with antineoplastic agents is mainly utilised in children with leukaemia and lymphoma, and in selected brain tumours. In these diseases, intrathecal use is restricted to methotrexate (MTX), cytosine arabinoside (Ara-C) and corticosteroids. A number of other agents are, at the present time, under evaluation. Intrathecal MTX administered sequentially with systemic high dose MTX infusion prolongs therapeutic cerebral spinal fluid (CSF) levels of the drug. Prolonged therapeutic CSF levels can also be achieved by giving repeated small intrathecal doses of MTX over an extended period in selected patients, with an implanted Ommaya reservoir. In the CSF, the metabolic inactivation of Ara-C is significantly lower than in plasma with a CSF clearance similar to the rate of CSF bulk flow. A slow-release formulation of Ara-C may be given intrathecally, resulting in a prolonged cytotoxic concentration in the CSF. CNS relapse and neurotoxicity in patients with acute lymphoblastic leukaemia, especially younger children, may be reduced by using age-related dosing of intrathecal MTX and Ara-C. Hydrocortisone is used in combination with MTX and Ara-C for so-called 'triple intrathecal chemotherapy' in the treatment of meningeal leukaemia. Intrathecal thiotepa does not appear to be advantageous over systemic administration in patients with brain and meningeal leukaemia. Monoclonal antibodies, reactive with tumour-associated antigens, can be used as delivery systems for chemotherapeutic agents and radionuclides. However, the development of this new approach is currently under evaluation in larger clinical studies. Neurological adverse effects may be expected with intrathecal chemotherapy and are increased by high dose systemic therapy, concomitant cranial radiotherapy or meningeal infiltration by neoplastic cells. Inadvertant intrathecal administration of antineoplastic agents that are indicated for systemic administration only, is dangerous and may result in a fatal outcome.

Efficient lentiviral transduction of primary human acute myelogenous and lymphoblastic leukemia cells.

BACKGROUND AND OBJECTIVES: Gene manipulation and cell vaccines represent innovative strategies to enhance the immunogenicity of cancer cells. We adopted a defective lentivirus derived from the human immunodeficiency virus (HIV)-1 backbone and carrying the enhanced green fluorescent protein (EGFP) gene to transduce primary human acute myelogenous leukemia (AML) and B-precursor acute lymphoblastic leukemia (ALL) cells. DESIGN AND METHODS: AML blasts were maintained with or without cytokines (stem cell factor, FLT3 ligand and interleukin 3) for 48 hours, and successively infected with two spin infection cycles. ALL blasts were cultured on a murine S17 stromal cell line. RESULTS: As regards AML cells, the efficiency of infection at 7 days varied from 8.4 to 37%. As confirmed by cell cycle analysis, cells were, in most of the cases, blocked in different phases of the cycle and did not proliferate during culture: the infection was therefore obtained in the absence of cell proliferation. In contrast, the maintenance of optimal cell viability was of fundamental importance for obtaining good infection levels. As regards ALL blasts, the percentages of infection after 3 days varied from 4.4 to 21%. INTERPRETATION AND CONCLUSIONS: These preliminary data suggest that gene delivery into primary human AML and B-precursor ALL cells by an HIV-1 derived lentiviral vector could represent a strategy for engineering leukemic cells for use as cancer vaccines.

Bone marrow transplantation for childhood hematological disorders: a global pediatric approach in a twelve year single center experience.

One hundred and 43 consecutive pediatric patients (June 1985-December 1996) with at least 18 months of follow-up, were considered: most of the patients (111/143, 77.6%) underwent allogeneic BMT. The median follow-up was 5.7 years. Overall survival and 5 years EFS were 48.6% and 46.9%, respectively. For patients who underwent allogeneic BMT from HLA-identical siblings, the 5 years EFS for ALL was 75% in 1st CR, 60.4% in 2nd CR, 22.3% in > 2nd CR and 86.7% for AML in 1st CR. The EFS for Allo-BMT in "good" and "poor" prognosis patients was 68.6% and 21.8%, respectively (p value = 0.001). Early mortality in Allo-BMT patients was 17.7% between 1985-1990 and 10.3% between 1991-1996. Early treatment-related organ complications occurred mostly in patients who underwent BMT from an unrelated or a mismatched family donor. Late toxicity was evaluated in 57 patients (median follow-up of 82 months): none of the patients complained of significant late cardiac or respiratory dysfunction. With regards to growth, 18/57 patients (31.6%) lost more than two height centile channels. Three cases of thyroid neoplasms were observed. Evaluation of psychosocial functioning, studied in 39 patients who had at least 2 years of follow-up in CR, did not reveal any evident quality of life impairment. The possibility of curing childhood hematological malignancies is based on a global pediatric and multidisciplinary approach. A continuous need to improve results in terms of EFS and quality of life suggests that further multicenter prospective studies should be carried out.