ALBERT

Description: WHIM syndrome (warts, hypogammaglobulinemia, infections, and myelokathexis) is a rare autosomal dominant immunodeficiency disorder that is caused by a gain in function in cysteine-X-cysteine chemokine receptor 4 (CXCR4) gene. Affected individuals have recurrent infections of the respiratory tract and soft tissues, and marked susceptibility to warts caused by human papilloma viruses (HPV). Patients have an increased risk of malignancy (lymphoma) and HPV-associated cancers. The optimal therapy for WHIM syndrome has not been defined and treatment has been with supportive care using intravenous immunoglobulin (IVIG) and granulocyte colony stimulating factor (G-CSF). New CXCR4 antagonist therapies are still in either phase I trials (plerixafor) or considered experimental (Chlacone-4). A successful umbilical cord blood transplant has been reported by Kriven et al. Here we describe a successful matched unrelated allogeneic stem cell transplant (SCT) in a girl with WHIM syndrome caused by a known mutation in the CXCR4 gene. This patient was diagnosed at birth with familial congenital neutropenia as findings were similar to those for the patient's mother and maternal grandmother. A complete blood count showed pancytopenia (WBC= 1.03 x103/µL, hemoglobin= 9.2 g/dL, platelet count= 74,000/µL, ANC= 70). Despite G-CSF and IVIG therapy, the patient had recurrent infections with sinusitis and pneumonia, along with progressive organomegaly with progressive pancytopenia. At the age of 4, the patient underwent matched unrelated SCT with a fully ablative regimen [busulfan 0.8 mg/kg/dose for 16 doses (days -9, -8, -7, and -6), cyclophosphamide 50 mg/kg/dose for 4 doses (days -5, -4, -3, and -2) and alemtuzumab 5 mg/day (weight-based dosage) for 3 doses (days -5, -4, and -3)]. Tacrolimus and mini methotrexate (on days +1, +3, +6 and +11) were given for GVHD prophylaxis. Neutrophil and platelet engraftment occurred on days + 21 and + 45, respectively. The patient is 100% donor chimeric. Post-transplant course has been complicated by grade II skin GVHD treated successfully with oral and topical steroids. The patient also developed adenovirus, BK virus and HHV-6 viral reactivations but without disease. The patient is now approximately 2 years post SCT with durable engraftment, normal humoral immune reconstitution and no chronic GVHD. Thus, stem cell transplant following myeloablative conditioning can be accomplished for patients with WHIM syndrome. Furthermore, transplantation performed at the patient's young age likely prevented complications of recurrent infections and warts. Disclosures Allen: NovImmune: Consultancy, Other: unpaid; Roche: Consultancy, Other: unpaid. Heslop:Cell Medica: Other: Licensing Agreement; Celgene: Other: Collaborative research agreement.

Description: Introduction: Matched related donor (MRD) hematopoietic cell transplant (HCT) is an accepted treatment for sickle cell disease (SCD) despite risk of graft-versus-host disease and graft rejection. Alemtuzumab is a potent lymphocytic medication that can reduce the risk of GVHD; however, it is associated with mixed donor chimerism (MDC) and graft loss when used with submyeloablative conditioning. We explored the use of myeloablative chemotherapy in conjunction with alemtuzumab in MRD HCT for SCD as a method to concurrently prevent GVHD and promote durable engraftment. Methods: We retrospectively reviewed engraftment, GVHD and survival for patients that underwent MRD HCT for SCD at Texas Children's Hospital between 2003-2017. All patients received busulfan dose adjusted to achieve target area under the curve of 800-1200μM per minute with doses administered intravenously every 6 hours for 4 days and cyclophosphamide 50mg/kg daily for 4 days. GVHD prophylaxis included intravenous alemtuzumab daily for 3-4 doses starting on day -5 (5-15kg=3mg, 15-30kg=5mg, 〉30kg= 10mg daily), methotrexate and a calcineurin inhibitor. Donor chimerism was evaluated via short tandem repeats (STR) or fluorescent-in-situ hybridization (FISH) of nucleated cells from the peripheral blood. If MDC was detected, follow-up chimerism studies were obtained every 1-4 weeks until stabilization on 2 or more consecutive evaluations. Persistent MDC was defined by the presence of recipient cells on 2 consecutive evaluations without return to full donor chimerism at last follow-up. Results: Thirty-eight consecutive patients underwent MRD transplant (3 non-sibling and 35 sibling) with a median age at transplant of 8.6 yrs (range: 2.9-18.4yr). Stem cell source consisted of bone marrow grafts for all patients. Two patients concurrently received cord blood from the same donor to augment cell dose. Neutrophil engraftment was achieved in all patients at a median time of 19 days (range: 13-24 days). Incidence of persistent MDC was 62.8% with a median last chimerism of 94% donor cells (range: 24-100%). Three of 22 patients (13.6%) with persistent MDC had

Description: Key PointsAllodepleted-T-cells containing the iC9 safety gene persist long-term in vivo, promote immune recovery, and protect against infections. GvHD caused by iC9-T cells can be permanently controlled by a single administration of AP1903 without abrogating immune reconstitution.

Description: Viral infection or reactivation remains a major cause of morbidity and mortality after allogeneic stem cell transplantation. We now show that infusions of single cytotoxic T lymphocyte (CTL) lines (5 × 106-1.35 × 108 cells/m2) with specificity for 2 commonly detected viruses, Epstein-Barr virus (EBV) and adenovirus, can be safely administered to pediatric transplantation recipients receiving partially human leukocyte antigen–matched and haploidentical stem cell grafts (n = 13), without inducing graft-versus-host disease. The EBV-specific component of the CTLs expanded in vivo and persisted for more than 12 weeks, but the adenovirus-specific component only expanded in vivo in the presence of concomitant adenoviral infection. Nevertheless, adenovirus-specific T cells could be detected for at least 8 weeks in peripheral blood, even in CTL recipients without viral infection, provided the adenovirus-specific component of their circulating lymphocytes was first expanded by exposure to adenoviral antigens ex vivo. After infusion, none of these 13 high-risk recipients developed EBV-associated lymphoproliferative disease, while 2 of the subjects had resolution of their adenoviral disease. Hence, bispecific CTLs containing both EBV- and adenovirus-specific T cells can safely reconstitute an antigen responsive “memory” population of CTLs after human leukocyte antigen–mismatched stem cell transplantation and may provide antiviral activity. This trial was registered at www.clinicaltrials.gov as #NCT00590083.

Description: Viral infections remain a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Adoptive immunotherapy with donor-derived virus-specific T cells (VSTs) has proven safe and effective for the prophylaxis and treatment of EBV, CMV, AdV, BKV and HHV-6 infections post-HSCT. However, broader application is restricted by the time taken to prepare patient-specific products and the lack of virus-specific T cell precursors in cord blood and seronegative donors. Thus, to assess whether 3rd party multivirus-directed VSTs could produce clinical benefit when administered as an "off the shelf" product to partially HLA-matched allogeneic HSCT recipients with drug-refractory BKV, EBV, CMV, AdV and/or HHV-6 infections we initiated a Phase II clinical trial (fixed cell dose of 2x107 VSTs/m2) using a bank of 59 VST lines generated from healthy, eligible donors. To date, 32 patients with one (n=28) or two (n=4) drug-refractory infections have been infused with lines matched at 1 to 6 HLA antigens. Fifteen patients received VSTs to treat CMV (including 3 cases of CMV colitis), 13 for BKV (11 for hemorrhagic cystitis, 2 for nephritis), 4 for AdV (including 1 case of pneumonia), 2 for HHV-6 (including 1 case of encephalitis) and 2 for EBV (including 1 case of EBV-PTLD). Twenty-one patients received just 1 infusion of cells, while 11 required 2 or 3 infusions for sustained benefit. Despite the HLA disparity between the VST lines and the recipients, de novo graft versus host disease (GVHD) occurred in only 1 subject, who developed Grade I skin GVHD that resolved with topical steroids. One additional patient had a flare of chronic skin GVHD coincident with tapering of immunosuppression and 2 patients developed transient fevers a few hours post-infusion, which spontaneously resolved within a couple of hours. Based on viral load, as measured by quantitative PCR, 3rd party VSTs successfully controlled active infections in 29 of 31 evaluable patients: CMV (9 CR, 5 PR, 1 NR); EBV (2 CR); AdV (2 CR, 1 PR, 1 NR); BKV (4 CR, 9 PR); and HHV-6 (1 PR). Of note, all 11 patients with BK hemorrhagic cystitis, 2 of 3 patients with CMV colitis, and the patients with AdV pneumonia and HHV-6 encephalitis, all had marked improvement or resolution of symptoms within 6 weeks following VST treatment. In more than 50% of responders (n=16) we detected an increase in the circulating frequency of VSTs post-infusion, which were confirmed to be 3rd party VST origin in 8 and remained detectable for up to 12 weeks post-infusion. The eventual decrease in 3rd party VSTs coincided with endogenous immune reconstitution in most patients. These results confirm the feasibility and safety of 3rd party multivirus-directed VSTs, administered as an "off the shelf" product to treat drug-refractory infections/disease. The infused cells were capable of expanding in vivo and proved clinically effective against refractory EBV, CMV, AdV, BKV and HHV-6 reactivation and virus associated disease. Disclosures Tzannou: ViraCyte LLC: Consultancy. Brenner:Viracyte: Equity Ownership; Cell Medica: Patents & Royalties. Rooney:Cell Medica: Membership on an entity's Board of Directors or advisory committees, Patents & Royalties; Viracyte: Equity Ownership. Heslop:Cell Medica: Patents & Royalties: Licensing agreement EBV-specific T cells; Viracyte: Equity Ownership; Chimerix: Other: Endpoint adjudication committee; Celgene: Patents & Royalties, Research Funding. Leen:ViraCyte LLC: Equity Ownership, Patents & Royalties.

Description: Despite advances in antiviral drugs, Cytomegalovirus (CMV) infections remain a significant cause of morbidity and mortality in immunocompromised individuals. We have recently demonstrated in hematopoietic stem cell transplant (HSCT) recipients that adoptively-transferred virus-specific T cells, generated from healthy 3rd party donors and administered as an "ready to administer" product, can be curative, even in patients with drug-refractory CMV infections. However, broader implementation has been hindered by the postulated need for extensive panels of T cell lines representing a diverse HLA profile, as well as the complexities of large scale manufacturing for widespread clinical application. To address these potential issues, we have developed a decision tool that identified a short list of donors who provide HLA coverage for 〉90% of the stem cell transplant population. Furthermore, to generate banks of CMV-specific T cells from these donors, we have created a simple, robust, and linearly scalable manufacturing process. To determine whether these advances would enable the widespread application of "ready to administer" T cells, we generated CMV cell banks (Viralym-C™) from 9 healthy donors selected by our decision tool, and initiated a fixed-dose (2x107 cells/m2) Phase I clinical trial for the treatment of drug-refractory CMV infections in pediatric and adult HSCT recipients. To generate the Viralym-C™ banks, we stimulated donor peripheral blood mononuclear cells (PBMCs) with overlapping peptide libraries spanning the immunodominant CMV antigens pp65 and IE1. Cells were subsequently expanded in a G-Rex device, resulting in a mean fold expansion of 103±12. The lines were polyclonal, comprising both CD4+ (21.3±6.7%) and CD8+ (74.8±6.9%) T cells, and expressed central CD45RO+/CD62L+ (58.5±4.2%) and effector memory markers CD45RO+/CD62L- (35.3±12.2%). Furthermore, the lines generated were specific for the target antigens (IE1: 419±100; pp65 1070±31 SFC/2x105, n=9). To date, we have screened 12 patients for study participation, and from our bank of just 9 lines we have successfully identified a suitable line for all patients within 24 hours. Of these, 6 patients have been infused; 5 received a single infusion and 1 patient required 2 infusions for sustained benefit. There were no immediate infusion-related toxicities; and despite the HLA disparity between the Viralym-C lines and the patients infused, there were no cases of de novo or recurrent graft versus host disease (GvHD). One patient developed a transient fever a few hours post-infusion, which spontaneously resolved. Based on viral load, measured by quantitative PCR, or symptom resolution (in patients with disease), Viralym-C™ cells controlled active infections in all 5 evaluable patients; 4 patients had complete responses, and 1 patient had a partial response within 4 weeks of cell infusion. One patient with CMV retinitis had complete resolution of symptoms following Viralym-C™ infusion. In conclusion, our results demonstrate the feasibility, preliminary safety and efficacy of "ready to administer" Viralym-C™ cells that have been generated from a small panel of healthy, eligible CMV seropositive donors identified by our decision support tool. These data suggest that cost-effective, broadly applicable T cell anti-viral therapy may be feasible for patients following HSCT and potentially other conditions. Disclosures Tzannou: ViraCyte LLC: Consultancy. Leen:ViraCyte LLC: Equity Ownership, Patents & Royalties. Kakarla:ViraCyte LLC: Employment.

Description: Congenital amegakaryocytic thrombocytopenia (CAMT) is a rare inherited bone marrow failure syndrome (IBMFS) characterized by decreased or absent numbers of megakaryocytes and is not associated with congenital malformations. It is an autosomal recessive disorder with mutations in the thrombopoietin receptor c-MPL, presenting at birth with severe isolated thrombocytopenia. Given the increased risk of life threatening hemorrhage, close monitoring and supportive care with regular platelet transfusions is usually required. The severity of the MPL mutation may predict the clinical course of children with CAMT. Null mutations may rapidly progress to pancytopenia and aplastic anemia, while more modest functional loss of receptor function cause a transient increase in platelet count to 〉 50,000/µL during the first year of life with later progression to pancytopenia. Moreover, like other IBMFSs, CAMT has been referred to as a cancer predisposition syndrome. Allogeneic hematopoietic stem cell transplant (HSCT) offers the only curative option. We present our institutional experience of three patients with CAMT who underwent matched unrelated HSCT early in the course of the disease when their presenting problem was isolated thrombocytopenia without pancytopenia, marrow failure or clonal evolution. We have used a fully ablative regimen with busulfan 1 mg/kg/dose for 16 doses (days -9, -8, -7, and -6), cyclophosphamide 50 mg/kg/dose for 4 doses (days -5, -4, -3, and -2) and alemtuzumab 3 mg/day (weight-based dosage) for 4 doses (days -5, -4, -3, and -2). Cyclosporine and mini methotrexate (on days +1, +3, +6 and +11) were given for GVHD prophylaxis. The first two patients were siblings with persistent thrombocytopenia at birth, the first of whom had compound heterozygous mutations (c.256dupC and c.391+5 G〉C) in the MPL gene. Both parents were carriers and the second sibling was diagnosed prenatally with the same mutations. No other phenotypic abnormalities were noted and testing for Fanconi anemia was negative. The siblings were transplanted with matched unrelated donors at 12 months and 14 months respectively. Our third patient was diagnosed prenatally with germinal matrix hemorrhage and vetriculomegaly. He was noted to have thrombocytopenia after birth. He was treated initially for presumed neonatal alloimmune thrombocytopenia. Sequencing of the MPL gene revealed two compound heterozygous missense mutations (R257C and R102P). The patient was transplanted with a matched unrelated donor at the age of 11 months. All patients tolerated the transplant with minimal toxicity, durable engraftment, and no acute or chronic GVHD. The first two siblings are approximately 4 years and 2 years post HSCT and the third patient is past day 100. Previous reports of HSCT for CAMT that used matched unrelated donors recorded poor outcomes, with a high rate of graft failure. Although our current study is small in size, the results suggest that a HSCT following a fully ablative regimen containing alemtuzumab and performed early in the course of the disease may produce better outcomes, and will avoid the complications associated with marrow failure and clonal abnormalities. Disclosures Allen: Roche: Consultancy, Other: unpaid; NovImmune: Consultancy, Other: unpaid. Heslop:Celgene: Other: Collaborative research agreement; Cell Medica: Other: Licensing Agreement. Brenner:Celgene: Other: Collaborative Research Agreement; Cell Medica: Other: Licensing Agreement; Bluebird Bio: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

Description: Since 1981, over 1600 patients with thalassemia have undergone allogeneic transplantation from matched related donors (MRD) with encouraging long term results. Unfortunately, the majority of patients do not have MRD and half of these patients die before age 35 from side effects of iron overload. Because advances in HLA typing and improvement in supportive care have resulted in comparable outcomes for children with leukemia transplanted from matched unrelated donor (MUD) we have been studying MUD transplantation in patients with hemoglobinopathies or with inherited severe anemia requiring chronic transfusion therapy. We used intravenous (IV) busulfan 12.8 mg/kg-16 mg/kg, cyclophosphamide 200 mg/kg, fludarabine 120 mg/m2, and Campath 1H. Tacrolimus was given as additional graft versus host disease (GvHD) prophylaxis. Here we report our experience with 8 patients: 2 ß-thalassemia major, 3 compound heterozygous Eß-thalassemia, 2 congenital sideroblastic anemia, and 1 Diamond-Blackfan anemia (DBA). The median age at transplantation was 4.5 years (2 yrs-11 yrs). Three patients were male and 5 were female. Seven patients were on chronic transfusion and chelation therapies. The median length of chronic transfusion therapy was 3.5 years (2yrs-5yrs) and of chelation therapy was 2 years (1yr-3yrs). The patient with DBA experienced intolerable side effects from chronic steroid therapy which became ineffective 1 year prior to transplant resulting in increasing transfusion frequency. One patient with thalassemia had been treated for acute lymphocytic leukemia (ALL) and was off chemotherapy for almost 4 years. Prior to transplant, all patients underwent liver biopsy which showed periportal fibrosis (stage 2–3) in 5 patients. Hepatic iron load ranged from 11,000 mcg/gm to 32,500 mcg/gm. Hence, the patients were class 1 or 2 according to the Pesaro risk classification. All patients engrafted. With a median follow-up of 12 months (1.5 months–16 months), donor chimerism remains at 100% in 6 patients and is between 86% and 100% in 2 patients. All patients are transfusion independent with median day of red blood cell (RBC) engraftment of 16 days (11 days–68 days). One patient required brief erythropoietin therapy for persistent non-transfusion dependent anemia. Acute GvHD occurred in 4 patients with 3 patients having GvHD grades 1–2. The patient who was previously treated for ALL had grade 4 GvHD to the skin, intestine, and liver. Post transplant liver biopsy for persistent elevated transaminases in 3 patients showed 1 CMV hepatitis, 1 mild to moderate GvHD, and 1 with idiopathic granulomatous inflammation. Other viral infections include 1 each of CMV bronchiolitis, BK virus hemorrhagic cystitis, and Parainfluenza type 1 bronchiolitis. All viral infections resolved with treatment. The patient previously treated for ALL died from GvHD and disseminated fungal infection. The overall disease free survival is 87% at 16 months. These initial promising results indicate that MUD stem cell transplant should be considered for patients with thalassemia and other inherited severe anemia who lack a matched sibling donor.