ALBERT

Description: The immunotherapeutic ablation of lymphoma is a conceptually attractive treatment modality that is the subject of intense translational research activities. One approach being piloted through the City of Hope Lymphoma SPORE is the application of cellular immunotherapy employing cytolytic T-lymphocyte (CTL) grafts genetically engineered for CD19-specific effector functioning. This has been achieved by the construction of a chimeric T-cell antigen receptor (CAR) composed of a CD19-specific single chain immunoglobulin variable fragment (scFv) extracellular targeting domain molecularly coupled to the CD3 complex zeta chain. Cytolytic T-cells that are genetically modified to express this CAR display HLA-independent CD19-specific recognition and killing of lymphoma target cells. Using clinically applicable plasmid gene transfer/selection systems our group has demonstrated that anti-CD19 CAR+/HyTK+ CD8+ effectors can be generated from CTL precursors present in the peripheral blood and expanded to clinically relevant cell doses. We have designed an FDA-authorized (BB-IND#11411) clinical trial in which patients with recurrent/refractory follicular lymphoma undergo leukapheresis and a polyclonal CTL product derived that a.) expresses the anti-CD19 CAR, b.) kills CD19+ lymphoma targets, c) remains dependent on exogenous IL-2 for survival and proliferation, and d.) is sensitive to ganciclovir ablation by virtue of co-expression of the selection-suicide transgene HyTK. The trial is designed to assess the safety of intra-patient dose escalation beginning at a cell dose of 100x106 cells/m2 escalating to a dose of 2,000x106 cells/m2. In addition, this trial employs the use of rituximab to clear circulating B-cells prior to the first T-cell dose and fludarabine following the first T-cell infusion to both induce temporary lymphopenia and limit anti-transgene rejection responses. The protocol employs low-dose subcutaneous rhuIL-2 to support the numerical and temporal persistence of transferred CTLs. Treated patients are monitored with immunologic correlative studies that include Q-PCR for tracking persistence of transferred CTLs, RT-QPCR for following the levels of CD19+ B-cells in the peripheral blood, bone marrow, and lymph nodes, as well as, CT and PET imaging studies to follow disease responses. Here, we report on our initial clinical experience treating patients on this trial.

Description: Genetic modification of cytolytic T-lymphocytes (CTL) for enhancing their functional immunobiology is a promising immunotherapeutic approach for the treatment of cancer and infectious disease. CTLs modified to express a chimeric antigen receptor comprising an extracellular IL13 domain and cytoplasmic CD3 domain (IL13-zetakine) can be re-directed both in vitro and in animal models to target glioblastoma multiforme (GBM), which is characterized by high expression of IL13Ralpha2. Patient-derived IL13-zetakine/HyTK expressing CD8+ CTL clones have entered early stage clinical trials. However, their clinical application is frequently limited in this patient population by the pervasive use of dexamethasone, a potent glucocorticoid analogue employed in the management of cerebral edema. Thus iatrogenic dexamethasone-mediated T-cell functional anergy and apoptosis in these patients is a barrier to realizing the full clinical utility of this adoptive therapy strategy. We hypothesized that knocking out the expression of the glucocorticoid receptor would render therapeutic CTLs resistant to the effects of synthetic glucocorticoids, including dexamethasone. We therefore developed engineered zinc finger nucleases (ZFNs) to specifically disrupt the glucocorticoid receptor (GR) locus in the human genome. ZFNs include the cleavage domain of the restriction enzyme FokI linked to an engineered zinc finger DNA-binding domain and can be designed to cleave a predetermined site in the genome. Natural repair of such DNA breaks via the error-prone non-homologous end joining pathway results in the inactivation of the target gene at frequencies which permit the isolation of knock out clones. Employing adenovirally delivered and transiently expressed ZFNs targeting exon 3 of the human GR gene, we isolated IL13-zetakine+ CD8+T-cells containing a biallelically mutated GR locus. These cells were characterized by the absence of full length GR protein, lack of glucocorticoid hormone-induced gene regulation and resistance to glucocorticoid hormone-mediated immunosupression and apoptosis. Importantly, the ZFN-modified, glucocorticoid-resistant CTLs demonstrated zetakine re-directed cytolytic activity and tumor cell specificity in chromium release assays in vitro and in an orthotopic mouse model of GBM in vivo. These results indicate that glucocorticoid-resistant IL13-zetakine targeted CTLs should retain function in cancer patients receiving glucocorticoids. A clinical trial to test this hypothesis is currently under development.

Description: Abstract 1417 Poster Board I-440 Gene-modified cellular products (GMCP) hold great promise for the management of numerous disease indications but are considered high-risk biological agents and are derived through extremely complex design and manufacturing processes. Thus, a robust Quality Management System (QMS) is essential for safe production of GMCP for clinical investigation. Development of a QMS that ensures compliance with current Good Manufacturing Practices (cGMP) and current Good Tissue Practices (cGTP) is particularly challenging in an academic setting where basic researchers, clinical investigators, regulatory, administrative, facilities and manufacturing personnel are all involved in the realization of a single GMCP. Following an ISO9001-based gap analysis of the Cellular Therapeutics program at the City of Hope, we implemented Quality Management Reports (QMR) as a tool for capturing data related to GMCP manufacturing. The QMR system was used to document and facilitate corrective and preventative actions (CAPA) as required following protocol deviation and/or Out of Specification (OOS) analyses. QMR data is captured in real-time and includes a detailed description of the event, impact analysis, root cause investigation, action plan and effectiveness analysis for resulting interventions. QMRs are documented using the Labware® (Wilmington, DE) Laboratory Information Management System (LIMS) that is available in real-time to authorized participants in GMCP production. A key aspect in the development of this on-line system was creation of links between the QMRs, OOS and CAPA documentation and investigation. The investigation database contains a series of templates: CAPA, SOP deviations, OOS and QMR that are designed to fully capture any events that impact or have the potential to impact quality, safety or efficient realization of a GMCP. The QMR process was applied to 2 manufacturing campaigns: a lentiviral vector-transfected CD34 GMCP for autologous transplantation in patients with AIDS lymphoma and a Master Cell Bank that was created for the treatment of patients with recurrent Glioblastoma Multiforme based upon an oligoclonal allogeneic T-cell product that contained both a chimeric antigen T-cell receptor and a zinc finger disrupted glucocorticoid receptor genomic sequence. Between May 2008-June 2009, 22 QMRs were generated related to product/reagent transfer, reagent quality/storage, equipment malfunction/OOS, product/environmental sterility, biological reagent OOS and Quality Control specifications for product release. Seventeen of 22 QMRs were resolved and closed. The average time to closing a QMR was 82 days (range 4-198 days). QMR findings lead to a revision of the program organizational chart, lead to the development and implementation of a new standard operating procedure (SOP) for Root Cause Analysis (RCA) investigations, development of new forms (GMP Equipment Approval Forms, a Quality Systems Project Proposal Form and Quality Assurance Customer Satisfactions Survey Forms), revisions to the SOP for CAPA and retraining of manufacturing staff as part of the resultant CAPA investigations to prevent repeat occurrences. Based upon QMR findings, 2 multidisciplinary RCAs were performed and resulted in revisions to documentation for CD34-cell selection and a major revision to the use of RODI water and manufacturing flow during GMCP production campaigns. Only 1 of 22 QMR-captured events has recurred (failure of an equipment monitoring system) and no events have re-occurred that might have had an impact upon product quality or safety. User satisfaction surveys performed by QA following the completion of a multidisciplinary RCA investigation indicate that the QMR process was viewed as fair, unbiased and transparent by a majority of the users (86% were either “Extremely Satisfied” or “Satisfied” with the experience). The QMR process is a powerful tool for the safe realization of GMCP and allows for real-time capture and multidisciplinary communication of complex events, including OOS that either individually or in aggregate may impact the purity, potency or safety of manufactured GMCP. These are often events that would not be routinely captured either as part of a batch record or merit CAPA. Because effectiveness analysis is included as part of the QMR process, it provides a key mechanism for continuous process improvement. Disclosures: Alvarnas: Novartis: Speakers Bureau.

Description: Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) niche, where they hide from chemotherapy and continue to divide. As yet, how leukemia cells alter the BM niche to facilitate their growth and assist them in evading chemotherapy is unclear. In this study, we provide compelling evidences that acute myeloid leukemia (AML), through exosome secretion, transformed the BM niche to facilitate their own growth and suppress normal hematopoiesis. Using AML xenograft and MLL-AF9 knock-in mouse model, we show that leukemia cells as well as AML-derived exosomes stimulate the growth of BM stromal progenitors and blocked the osteolineage development in our stromal compartment analysis. Histological analysis and micro-CT examination confirmed loss or thinning of the bone in both leukemia and leukemic exosome-treated animals. Expression of cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt2 and VEGF) are upregulated, whereas genes important for HSC maintenance (CXCL12 and SCF), osteoblast (OCN, OSX, Notch3 and IGF1) and chondrocyte (ACAN, SOX9) development are suppressed. While we observed increases in phenotypic LT-HSC in AML-derived exosomes treated mice, these mice show reduced multilineage reconstitution ability, increased cell cycle entry and higher sensitivity to myeloablative stress suggesting that HSCs from exosome-treated mice have lower stem cell activity than their counterparts from normal mice.In addition, leukemia-modified stroma cells exhibit marked reduction in ability to support normal HSCs. Pre-treatment of AML-derived exosome “prime” the animal for leukemia cell invasion and accelerate leukemia progression. Conversely,disruption of exosome secretion by targeting Rab27a in AML cells significantly delays leukemia progression. These data strongly support the notion that leukemia-modified niches favor leukemic cell proliferation and suppress normal hematopoiesis. Disclosures No relevant conflicts of interest to declare.

Description: Background: Autologous stem cell transplantation (ASCT) has become an accepted treatment option for high risk or relapsed ARL. Treatment related mortality is similar to the HIV negative setting. However, ultimately further improvement in ASCT will depend on both effective anti lymphoma therapy and better control of the HIV infection. Highly active antiretroviral therapy (HAART) can lower HIV viral loads to undetectable levels in the peripheral blood, but reservoirs of HIV are still present in the tissues and acquired resistance to HAART also remains a problem. A treatment strategy that would confer intrinsic resistance to HIV could circumvent theses issues. Herein we report on one such strategy using multiplexed RNA based anti-HIV gene transfer strategies to render autologous peripheral blood progenitor cells resistant to HIV. Patients with high risk ARL deemed candidates for ASCT were eligible. Seven subjects with NHL have been enrolled. (4PR, 2 REL, 1CR2), of whom 2 failed screening phase, 1 failed product release test, 2 are pending transplant, and 2 patients have undergone successful transplantation. Median age was 43 yrs at enrollment. Four pts to date were mobilized with chemotherapy plus GCSF and cells were collected for the clinical product (Fx1) and for CD34-selection (CliniMACSª, Miltenyi) and research treatment (Fx2). (see table ) UPN # Fx1 (CD34+/kg) Fx2 (CD34+/kg) Post Selection and transductionCD34+/kg 301 2.8X106 3.5X106 .26 X106 not infused 304 3.9X106 3.6X106 1.2 X106 305 3.4X106 3.8X106 1.4X106 306 5.6X106 8.8X106 pending Three days prior to the completion of CBV (cyclophosphamide 100mg/kg, BCNU 450mg/ m2, VP16 60mg/kg) conditioning, the Fx2 cells were thawed and transduced with a lentivirus vector (LV,rHIV7-ShI-TAR-CCR5Z) encoding 3 RNA elements including short hairpin RNA (shRNA) targeted to HIV tat/rev, a nucleolar localizing TAR decoy sequence, and a ribozyme targeted to CCR5. Cell viability post transduction ranged between 52–64% in three pts. On day 0 Fx2 is given and Fx1 is given 24hrs later (day+1). UPN301 did not receive the transduced Fx2 cells due to a low cell dose. For UPN304 and 305 who received the gene modified Fx2 cells, WBC engraftment occurred at day +11, platelet engraftment at day+16, and there have been no serious adverse events. Results to date at 30 and 60 days post ASCT reveal peripheral blood marking consistent with the ratio of gene modified to unmodified cells infused. Q-PCR analysis demonstrated distribution of genetically modified cells in myeloid and lymphoid lineages, and RT-PCR evidence of shRNA in progeny cells provided further evidence of successful transduction and engraftment of progenitor cells. Follow-up data for these and subsequent patients will be presented at the meeting. Conclusion: Lentiviral vector transduction of autologous peripheral blood progenitor cells with multiplexed RNA is feasible, well tolerated, and led to successful engraftment following high dose chemotherapy for ARL.

Description: Increasing evidence suggests that leukemia cells take shelter in the bone marrow (BM) microenvironment (niche), where they hide from chemotherapy and continue to divide. As yet, the identity of niche cells and secreted factors that facilitate leukemia cell growth and assist them in evading chemotherapy is unclear. Further, how leukemia cells alter the bone marrow microenvironment is not known yet. In this study, we provide compelling evidences of a novel role of leukemia-derived exosomes in altering the microenvironment constituents by paracrine mechanisms.As proof-of-concept, we analyzed the cytokines mRNA profiles of primary human and mouse stromal cell co-cultured with primary CD34+CD38- cells from AML patients. Stromal cells co-cultured with leukemia showed increased levels of IL-6, IL-1β, VEGFα, TNF and reduced SDF1 mRNA expression. Similar pattern of gene expression changes were observed from stroma cells co-cultured with leukemia-derived exosomes.By using CFSE labeled exosomes, we observed that leukemia-derived exosomes target marrow stromal and endothelial cells both in-vitro and in-vivo directly. In our in vivo AML model, established using xenografted AML cell lines or primary AML patient samples in Rag2-/- γc-/-mice, we observed expansion of LT-HSC and hematopoietic progenitors compartment. The leukemia animals also showed cellular composition changes in the stromal compartment suggesting osteoblast differentiation was blocked. Interestingly, milder but similar changes were observed in mice treated with leukemia-derived exosomes. Exosomes derived from normal human peripheral blood did not induce significant changes in either hematopoietic or stromal compartments in recipient mice. These data indicate that leukemia cells secrete specialized exosomes to modulate the BM microenvironment. Fluidigm dynamic array analysis of BM stromal cells from leukemic mice revealed that the cell adhesion molecules (NCAM1, VCAM1, CD44, OPN & ICAM1) and factors important for angiogenesis (Angpt1, Angpt 2 &VEGF) were all upregulated in leukemia-modified stromal cells whereas genes important for osteoblast (OCN, OSX), chondrocyte (SOX9) development and HSC maintenance (SDF1 and SCF) were down regulated. These results suggest that leukemia cells can remodel the BM microenvironment by changing the stromal cell composition and influencing expression of important molecular regulators. To evaluate the HSC functions in exosomes-treated mice, we used 5-fluorouracil (5-FU) to suppress hematopoiesis and induce myeloablative stress. Leukemia-derived exosome-pretreated mice succumbed to death earlier compared to the control group (p=0.0001) suggesting that HSCs from leukemia-derived exosome-treated mice may have lower stem cell activity than their counterparts from normal mice. Furthermore, more LT-HSC and hematopoietic progenitors from leukemia-derived exosome-pretreated mice were in active cell cycle (p=0.004 and p=0.01 respectively). These findings support our hypothesis that leukemia cells/exosomes directly or indirectly through leukemia-modified niche, altered the HSCs physiological and quiescence properties. Next we analyzed the ability of leukemia-modified niche to support the normal hematopoiesis. We co-cultured freshly sorted normal CD45.2 LT-HSCs (LSK CD150+CD48-Flk2-) with leukemia cells/exosomes pre-treated stroma cells for 48 hours and transplanted the co-cultured HSC into irradiated CD45.1 mice. 18 weeks after transplantation, we observed a significantly decreased engraftment of the HSCs co-cultured with leukemic cells/exosomes stroma compared with the HSCs co-cultured with normal stroma (p=0.003). Finally, leukemia engrafted better and developed more rapidly (p=0.0026) in mice that received leukemia-derived exosomes pre-treatment. These data suggest that changes induced by leukemia-derived exosomes in the BM niche accelerate leukemia progression and decrease their ability to support HSCs. Collectively, our data demonstrate that the leukemia cells manipulate the bone marrow microenvironment, partly through leukemia-derived exosomes, to suppress the normal hematopoiesis and facilitate growth of the leukemic progeny. Disclosures: No relevant conflicts of interest to declare.