Efficacy of deferred dosing of granulocyte colony-stimulating factor in autologous hematopoietic transplantation for multiple myeloma.

Routine administration of G-CSF following autologous hematopoietic SCT (ASCT) expedites ANC recovery and reduces hospitalization by 1-2 days; it has no impact on febrile neutropenia, infections, morbidity, mortality, event-free survival or OS. To determine whether delayed G-CSF dosage could result in equivalent ANC recovery and thereby improve cost effectiveness, we deferred the administration of G-CSF until WBC recovery had begun. A total of 117 patients with multiple myeloma received ASCT from January 2005 to September 2012. Of these, 52 were in the conventional dosing group (CGD) and received G-CSF from Day +7 for a median of five doses. In the deferred dosing group (DGD), 65 patients received G-CSF from median day 14 post transplant for a median of zero doses. There was no difference between groups in the incidence or duration of febrile neutropenia, duration of grade III mucositis, weight gain, rash, engraftment syndrome or early death (100 days). The DGD group had a significantly longer time to neutrophil engraftment than the CGD group (15 days vs 12 days; P<0.0001), a longer period of severe neutropenia (<100/µL; 8 days vs 6 days; P<0.0001), longer treatment with intravenous antibiotics (7 days vs 5 days; P=0.016) and longer hospital stay (19 days vs 17 days; P=<0.0001). Although the cost of G-CSF was lower in the DGD group (mean $308 vs $2467), the additional hospitalization raised the median total cost of ASCT in this group by 17%. There was, however, no adverse effect of deferred dosing on the rate of febrile neuropenic episodes or Day 100 survival, so that deferred dosing of G-CSF may be suitable for patients receiving ASCT as outpatients, for whom longer hospital stay would not be an offsetting cost.

Robust T cell responses to aspergillosis in chronic granulomatous disease: implications for immunotherapy.

Chronic granulomatous disease (CGD) patients are highly susceptible to invasive aspergillosis and might benefit from aspergillus-specific T cell immunotherapy, which has shown promise in treating those with known T cell defects such as haematopoietic stem cell transplant (HSCT) recipients. But whether such T cell defects contribute to increased risks for aspergillus infection in CGD is unclear. Hence, we set out to characterize the aspergillus-specific T cell response in CGD. In murine CGD models and in patients with CGD we showed that the CD4(+) T cell responses to aspergillus were unimpaired: aspergillus-specific T cell frequencies were even elevated in CGD mice (P < 0·01) and humans (P = 0·02), compared to their healthy counterparts. CD4-depleted murine models suggested that the role of T cells might be redundant because resistance to aspergillus infection was conserved in CD4(+) T cell-depleted mice, similar to wild-type animals. In contrast, mice depleted of neutrophils alone or neutrophils and CD4(+) T cells developed clinical and pathological evidence of pulmonary aspergillosis and increased mortality (P < 0·05 compared to non-depleted animals). Our findings that T cells in CGD have a robust aspergillus CD4(+) T cell response suggest that CD4(+) T cell-based immunotherapy for this disease is unlikely to be beneficial.

The immunogenicity of virus-derived 2A sequences in immunocompetent individuals.

Genetic engineering of T cells for adoptive immunotherapy in cancer patients has shown significant promise. To ensure optimal antitumor activity and safety, the simultaneous expression of multiple genes is frequently required, and short viral-derived 2A sequences are increasingly preferred for this purpose. Concerns exist, however, that these virus-derived sequences may induce unwanted immune responses, and thus diminish persistence of the gene-modified cells after adoptive transfer. Whereas such responses were absent in immunocompromised recipients, potential immunogenicity in immunocompetent individuals remains a concern. We now address whether ex vivo T cell responses can be elicited against the most widely used 2A sequences (2A-Thosea asigna virus (TAV) or 2A-equine rhinitis virus (ERAV), specifically) in immunocompetent individuals. We used a potent ex vivo culture system previously validated to induce T cell responses even against weakly immunogenic antigens. Of the sixteen donors tested, only five released very low levels of interferon-γ in response to 2A-TAV peptide mixtures (single peptide specificity in three donors, adjacent self-antigen peptide specificity in one donor and nonspecific reactivity in one donor). None of them produced cytotoxic activity or responded to 2A-ERAV. These results suggest that exposure to viral-derived 2A sequences is unlikely to produce unwanted T cell responses in immunocompetent individuals and further supports their continued use for studies of human gene therapy.

Engineering CD19-specific T lymphocytes with interleukin-15 and a suicide gene to enhance their anti-lymphoma/leukemia effects and safety.

T lymphocytes expressing a chimeric antigen receptor (CAR) targeting the CD19 antigen (CAR.19) may be of value for the therapy of B-cell malignancies. Because the in vivo survival, expansion and anti-lymphoma activity of CAR.19(+) T cells remain suboptimal even when the CAR contains a CD28 costimulatory endodomain, we generated a novel construct that also incorporates the interleukin-15 (IL-15) gene and an inducible caspase-9-based suicide gene (iC9/CAR.19/IL-15). We found that compared with CAR.19(+) T cells, iC9/CAR.19/IL-15(+) T cells had: (1) greater numeric expansion upon antigen stimulation (10-fold greater expansion in vitro, and 3- to 15-fold greater expansion in vivo) and reduced cell death rate (Annexin-V(+)/7-AAD(+) cells 10+/-6% for iC9/CAR.19/IL-15(+) T cells and 32+/-19% for CAR.19(+) T cells); (2) reduced expression of the programmed death 1 (PD-1) receptor upon antigen stimulation (PD-1(+) cells <15% for iC9/CAR.19/IL-15(+) T cells versus >40% for CAR.19(+) T cells); and (3) improved antitumor effects in vivo (from 4.7- to 5.4-fold reduced tumor growth). In addition, iC9/CAR.19/IL-15(+) T cells were efficiently eliminated upon pharmacologic activation of the suicide gene. In summary, this strategy safely increases the anti-lymphoma/leukemia effects of CAR.19-redirected T lymphocytes and may be a useful approach for treatment of patients with B-cell malignancies.

Outcome of hematopoietic stem cell transplant as salvage therapy for Hodgkin's lymphoma in adolescents and young adults at a single institution.

For patients with relapsed Hodgkin's lymphoma (HL), high dose chemotherapy with stem cell rescue (HDCT-SCT) may improve survival over chemotherapy alone. We assessed the outcomes of HDCT-SCT in 37 consecutive adolescent and young adult patients with relapsed HL whose malignancy was categorized based on sensitivity to chemotherapy. We determined whether current outcomes supported the use of HDCT-SCT in all of our patients or just those patients with lower-risk characteristics such as chemosensitivity. With a median follow-up of 6.5 years, the 2-year overall survival (OS) was 89% (95% CI: 62-97%) for the chemosensitive patients (n = 21), whereas for patients with resistant disease (n = 16), OS was 53% (95% CI: 25-74%). Both autologous and allogeneic transplants were well tolerated, with 100-day treatment-related mortality under 10%. Our data show encouraging outcomes for patients with chemosensitive relapsed HL who receive hematopoietic stem cell transplant (HSCT) and support the value of the procedure even when the disease is chemoresistant.

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.

Hematopoietic stem cell transplantation in patients with sporadic amyotrophic lateral sclerosis.

BACKGROUND: Amyotrophic lateral sclerosis (ALS), an inexorably progressive motoneuron disease, is accompanied by significantly increased markers of inflammation. These inflammatory constituents could protect, harm, do neither, or do both. OBJECTIVE: Allogeneic hematopoietic stem cell transplantation (HSCT) was performed in patients with sporadic ALS to suppress neuroinflammation and improve clinical outcomes after CNS engraftment. METHODS: Six patients with definite ALS received total body irradiation followed by peripheral blood HSCT infusion from human leukocyte antigen identically matched sibling donors. Disease progression and survival were assessed monthly and compared with matched historic database patients. Autopsy samples from brain and spinal cord were examined immunohistochemically and by quantitative reverse-transcriptase polymerase chain reaction. Donor-derived DNA in brain and spinal cord tissue was evaluated for the extent of chimerism. RESULTS: No clinical benefits were evident. Four patients were 100% engrafted; postmortem tissue examination in two of the 100% engrafted patients demonstrated 16% to 38% donor-derived DNA at sites with motoneuron pathology, which may correspond to the observed increased CD68 or CD1a-positive cells. Neither donor DNA nor increased cell numbers were found in several unaffected brain regions. A third minimally engrafted patient had neither donor DNA nor increased infiltrating cells in the CNS. CONCLUSIONS: This study demonstrates that peripheral cells derived from donor hematopoietic stem cells can enter the human CNS primarily at sites of motoneuron pathology and engraft as immunomodulatory cells. Although unmodified hematopoietic stem cells did not benefit these sporadic amyotrophic lateral sclerosis patients, such cells may provide a cellular vehicle for future CNS gene therapy.

Flanking-sequence exponential anchored-polymerase chain reaction amplification: a sensitive and highly specific method for detecting retroviral integrant-host-junction sequences.

BACKGROUND: Retroviral vectors are regularly used to transduce stem cells and their derivatives for experimental and therapeutic purposes. Because these vectors integrate semi-randomly into the cellular genome, analysis of integranated retroviral DNA/host cell DNA junctions (IHJ) facilitates clonality studies of engrafted cells, allowing their differentiation, survival and fate to be tracked. In the case of any adverse events, IHJ analysis can allow the identification of potentially oncogenic integration sites. At present, most measures to assess IHJ are complex, insensitive and may be subject to IHJ selection bias inherent to the technology used. METHODS: We have developed and validated a simple but effective technique for generating libraries of IHJ, which we term flanking-sequence exponential anchored-polymerase chain reaction (FLEA-PCR). Flanking-sequence random anchoring is used as an alternative to restriction enzyme digestion and cassette ligation to allow consistent detection of IHJ and decrease bias. RESULTS: Individual clones from plasmid libraries can be sequenced and assembled using custom-written software, and FLEA-PCR smears can be analyzed by capillary electrophoresis after digestion with restriction enzymes. DISCUSSION: This approach can readily analyze complex mixtures of IHJ, allowing localization of these sequences to their genomic sites. This approach should simplify analysis of retroviral integration.

Adoptive cellular immunotherapy for viral diseases.

Viral infections remain a major cause of morbidity and mortality after pediatric hematopoietic stem cell transplantation. Adoptive transfer of donor-derived virus-specific T cells can reconstitute antiviral immunity in recipients and be effective both in preventing and treating cytomegalovirus, Epstein-Barr virus and adenovirus infection. Current efforts are focused on providing protection toward a broader range of viruses safely, rapidly and effectively.

Transmission of integrated human herpesvirus-6 in allogeneic hematopoietic stem cell transplantation.

Human herpesvirus 6 (HHV-6) viremia, as detected by polymerase chain amplification, occurs in approximately half of allogeneic hematopoietic stem cell transplant recipients. The significance of such viremia is incompletely understood, but HHV-6 encephalitis and bone marrow suppression are increasingly being recognized in patients with high viral DNA. We report two patients in whom donor-to-recipient transmission occurred through hematopoietic transplant by means of chromosomally integrated (CI) HHV-6. Iatrogenic transmission manifested at engraftment as asymptomatic elevation of HHV-6 viral DNA of 3600 and 15 400 DNA copies/ml in plasma and 6.1 x 10(6) and 9.7 x 10(5) DNA copies/ml in the whole blood. Both donors had elevated plasma HHV-6 PCR at 5.6 x 10(4) and 1.3 x 10(5) DNA copies/ml and strikingly elevated whole blood HHV-6 levels at 4.1 x 10(6) and 4.7 x 10(6) DNA copies/ml, respectively. CI of the virus was traced to the mother of one patient and his donor. CI of HHV-6 may confound the interpretation of HHV-6 viremia after stem cell transplantation; consideration of the possibility of CI HHV-6 will avoid unnecessary antiviral therapy.

Reconstitution of adenovirus-specific cell-mediated immunity in pediatric patients after hematopoietic stem cell transplantation.

Adenovirus (adv) is a significant cause of morbidity and mortality in pediatric hematopoietic stem cell transplant recipients, and control of infection seems to require antigen-specific T cells. We evaluated the recovery of adv-specific cellular immunity in this patient population related to degree of T-cell immunosuppressive therapy and compared this to adv cellular immunity of normal donors. Over 12 months, we monitored for adv DNA in stool and blood of patients and in the blood of a normal donor group. Twenty-two pediatric hematopoietic stem cell transplant (HSCT) patients (14 months-20 years) who received matched-related (MRD n=6), mismatched related (Haplo n=6) or matched unrelated donor (MUD n=10) grafts, were followed and results compared to healthy controls (n=8). Adv was detected by polymerase chain reaction in blood and/or stool from 81.8% of patients on at least one occasion post-HSCT, but only 68% of patients developed symptomatic adv infections. Recovery of adv-specific T cells was significantly delayed in the MUD and Haplo recipients, whereas recovery in the MRD group was similar to levels detected in healthy donors within 30 days post-transplant. In conclusion, recipients of alternative donor transplants at our institution have significantly delayed adv-specific cellular immune recovery, which correlates to an increased risk of adv-associated morbidity and mortality.

Human herpesvirus-6 encephalitis following allogeneic hematopoietic stem cell transplantation.

Immunosuppressive monoclonal antibodies directed to immune system cells may reduce rejection and graft versus host disease (GvHD) after allogeneic stem cell transplantation (SCT), but can increase the risks of viral infection. Here, we report human herpes virus-6 (HHV-6) encephalitis despite antiviral prophylaxis in 5 of 43 (11.6%) patients receiving alemtuzumab supported conditioning. Encephalitis occurred at 41-103 days (median 60 days) presenting with confusion in all patients, combined with amnesia (n=3) or seizures (n=2). MRI revealed non-specific white matter changes in two and a non-enhancing medial temporal lobe lesion in three patients. Cerebrospinal fluid (CSF) PCR amplification for HHV-6 was positive in all five patients, (600-2 25 000 (median 4700) copies/ml CSF), while analysis of peripheral blood revealed 100-22 500 (median 1200) viral copies/ml plasma. CSF protein was elevated in four patients, with minimal CSF pleocytosis. Intravenous foscarnet produced neurological improvement at 8-13 (median 11) days and negative plasma PCR at 30-66 (median 50) days. Four patients had complete neurological recovery, but one patient with persistent viral DNA in the CSF succumbed to progressive encephalopathy. Given this high incidence of HHV-6 and the possibility of successful outcome with prompt treatment, a high index of suspicion of this disorder is required in recipients of monoclonal antibody supported allografts.

Outcome of reduced-intensity allogeneic hematopoietic stem cell transplantation (RISCT) using antilymphocyte antibodies in patients with high-risk acute myeloid leukemia (AML).

Hemopoietic stem cell transplantation (SCT) with fully ablative conditioning is associated with an age-related increase in treatment-related mortality. It is therefore particularly unsuited to older individuals, who are most at risk of developing acute myeloid leukemia (AML). Reduced-intensity SCT (RISCT) may be of value in this group. We report 17 consecutive patients with high-risk AML whose median age was 58 years and who received stem cells from HLA-matched siblings (n=5), or alternative donors (n=12). We used lymphodepleting antibodies as a part of the reduced-intensity conditioning regimen to limit the risk of graft rejection and graft-versus-host disease (GVHD). All patients engrafted. One patient developed severe fatal GVHD, and two patients died of infection. At a median follow-up of 861 days (372-1957 days), seven patients are alive in remission, which includes two patients treated in relapse and five patients who lacked an MHC identical sibling donor. Both progression-free survival and overall survival are 40% (95% CI, 17-64%). Hence, RISCT using lymphodepleting antibodies may be of value for older patients with AML, even in those with active or high-risk disease, and even if they lack an MHC-identical sibling donor.

T cell therapies.

T cell therapies are increasingly used for the treatment of malignancies and viral-associated diseases. Initial studies focused on the use of unmanipulated T cell populations after allogeneic stem cell transplantation. More recently, the use of antigen-specific T cells has been explored. This chapter reviews the clinical experience with polyclonal Epstein-Barr virus (EBV)-specific cytotoxic T cells (CTL) for the treatment of EBV-associated malignancies. Strategies on how to improve the antitumor activity of EBV-specific CTL are being discussed. If effective, these strategies will have broad implications for T cell therapies for a range of human tumors with defined antigens.

Adenovirus infection rates in pediatric recipients of alternate donor allogeneic bone marrow transplants receiving either antithymocyte globulin (ATG) or alemtuzumab (Campath).

Infectious complications due to adenovirus are of increasing concern after allogeneic stem cell transplantation. Over the past 4 years, we have modified our conditioning regimens to use alemtuzumab in preference to anti-thymocyte globulin (ATG) for pediatric patients receiving stem cell transplants from alternate donors. Recent reports in adult studies implicate alemtuzumab as a risk factor for adenovirus infection. We therefore evaluated the incidence of adenovirus infection in pediatric patients receiving either ATG or alemtuzumab in their conditioning regimens. Of the 111 patients evaluated, a total of 54 patients received ATG and 57 patients received alemtuzumab. In total, 35/111 (32%) patients were infected by adenovirus, and 9/111 (8%) had adenovirus disease (AD). Adenovirus infection was greater in the alemtuzumab group than the ATG group (23/57 vs 12/54) (P=0.039) and disseminated AD was more frequent in the alemtuzumab group vs the ATG group (8/57 and 1/54 respectively) (P=0.032). The presence of Grade 3-4 graft-versus-host disease was a risk factor for adenovirus infection. Our findings highlight the fact that adenovirus infection is a frequent complication after stem cell transplantation from alternate donors in the pediatric population and that alemtuzumab increases the risk of infection compared to ATG. This work will help in identifying at-risk populations for our upcoming immunotherapy trial using adoptively transferred donor-derived adenovirus-specific cytotoxic T lymphocytes.

Cytomegalovirus (CMV) infections and CMV-specific cellular immune reconstitution following reduced intensity conditioning allogeneic stem cell transplantation with Alemtuzumab.

We studied the incidence and recurrence of Cytomegalovirus (CMV) infection and reactivation in 38 recipients of Alemtuzumab reduced intensity conditioning-stem cell transplantation, and used CMV-HLA tetramer studies to discover if these events correlated with recovery of circulating CMV-specific CD8+ T cells (cytotoxic T lymphocyte (CTLs)). The cumulative incidence of CMV infection was 60% at 1 year (95% CI, 45-78%) with a median reactivation time of 24 days (range 5-95 days). All patients with CMV reactivation received Ganciclovir or Foscarnet, and only one developed CMV disease. More strikingly, only 8/21 patients had relapse of CMV antigenemia. Tetramer analysis in 13 patients showed that 11 reconstituted CMV CTLs (7/11 by day 30 and 10/11 by day 90). The development of CMV infection was accompanied by a >5-fold rise of CMV CTLs. Recurrence of CMV infection occurred only in the patients who failed to generate a CTL response to the virus. Hence, recipients of SCT using Alemtuzumab-RIC are initially profoundly immunosuppressed and have a high incidence of early CMV reactivation. However, in the majority of patients, infection is transient, and antiviral T cell reconstitution is rapid. Monitoring with CMV-specific CTLs may help identify the subset of patients at risk from recurrent infection or disease.

Current status of genetic modification of T cells for cancer treatment.

Clinical studies of adoptive immunotherapy with T cells have shown activity directed at hematologic and solid malignancies and viral infections. Genetic modification of infused T cells offers the prospect of improving such therapies and has already been used to track infused T cells, insert suicide genes and redirect the immune response towards specific Ag. Pre-clinical studies are evaluating novel approaches to genetically modify T cells to confer resistance to tumor evasion mechanisms. There is also increasing interest in developing suicide gene strategies as a failsafe mechanism to eradicate genetically modified cells should adverse effects occur.