Allogeneic Immunotherapy for cancer and nonmalignant hematological disorders

National Heart, Lung, And Blood Institute

Investigators

Linked publications & trials

Abstract

Our group has demonstrated that an allogeneic graft-versus-RCC effect can occur after hematopoietic stem cell transplantation. We have subsequently conducted studies investigating the immunological mechanisms accounting for tumor regression in patients demonstrating an anti-RCC effect in attempts to identify both the effector cell populations mediating these regressions as well as their target antigens. Using c-DNA expression cloning, we have recently identified a novel tumor antigen derived from a human endogenous retrovirus over-expressed in RCC cells called HERV-E CT-RCC. This antigen is not expressed on normal tissues and therefore could potentially serve as a target for a future kidney cancer vaccine. Work to identify other antigens derived from this HERV-E that are expressed on common HLA molecules as well as efforts to develop a monoclonal antibody that recognizes HERV-E derived proteins that are selectively expressed in RCC are ongoing. Finally, we have also sought to characterize the mechanisms accounting for selective expression of the CT-RCC HERV-E in RCC. Recent data shows the VHL tumor suppressor gene regulates expression of this newly identified tumor antigen, potentially accounting for selective expression of the CT-RCC HERV-E in the clear cell variant of RCC. We have also developed a murine model of allogeneic SCT in hosts bearing metastatic RCC, in which reproducible GVT effects occur, extending animal survival compared to recipients of autologous transplants. We have used this model to explore whether adoptive transfer of donor NK cells can be used to bolster GVT effects against cancer after allogeneic HCT. Our group has shown that KIR incompatible NK cells are cytotoxic to solid tumor cells in vitro. Using the above mentioned animal model, we have shown that a single infusion of alloreactive NK cells can significantly reduce GVHD and prolong survival in mice with RCC undergoing allogeneic HCT. Based on these findings, we plan to evaluate if the incidence of acute grade II-IV GVHD can be reduced and GVT effects can be enhanced against RCC after allogeneic HCT by adoptively infusing donor NK cells. We are also exploring methods to sensitize solid tumors to NK cell attack by altering the phenotype of tumor cells through targeted gene induction. Recently we showed that bortezomib and depsipeptide sensitize tumors to NK cell cytotoxity by enhancing NK-cell mediated TRAIL killing. We have also developed a method to expand by >4 logs NK cells from healthy donors for adoptive infusion in future NK-cell based adoptive immunotherapy trials. We now have developed a method to expand human NK cells by 100 to 1000 fold in bags using GMP conditions. A phase I study entitled Safety and the anti- tumor effects of escalating doses of adoptively infused ex vivo expanded autologous natural killer cells against metastatic cancers or hematological malignancies sensitized to NK TRAIL cytotoxicity with Bortezomib was initiated in 2008 and is currently accruing patients. Our group continues to explore the use of allogeneic SCT in patients with nonmalignant diseases such as PNH or ATG-Refractory severe aplastic anemia. In vitro studies conducted in our laboratory have shown PNH cells are equally sensitive to allogeneic immune attack as normal GPI-positive immune cells. At present, 56 patients with bone marrow failure syndromes including SAA/PNH have been transplanted following conditioning with fludarabine, ATG and cyclophosphamide followed by infusion of an un-manipulated G-CSF mobilized allograft from an HLA matched or single antigen mismatched relative. Despite a high prevalence of pre-transplant allo-immunization, graft rejection and/or graft failure did not occur, with all patients achieving sustained donor engraftment in both myeloid and T-cell lineages. With a median follow-up of 4.5 years, overall survival has been excellent at 87.1%. The cumulative incidence of Grade II-IV, acute GVHD was 51.8% and the cumulative incidence of chronic GVHD was 72%. Remarkably, patients who achieved full donor T-cell engraftment by day 30 were significantly more likely to develop cGVHD compared to patients that had more delayed donor T-cell engraftment. Efforts to reduce the high incidence of GVHD associated with this approach without increasing the risk of graft failure by manipulating the cellular content of the allograft to delay the rapidity of donor T-cell engraftment are currently being explored. Specifically, we have initiated a new clinical transplant trial for patients with bone marrow failure syndromes which uses the same conditioning regimen with a modified donor allograft containing G-CSF mobilized hematopoietic progenitor cells which have been selected for CD34+ cells combined with non-G-CSF mobilized T-cells. The total T-cell dose has been reduced by one log compared to T-cell dose infused with the prior T-cell replete G-CSF mobilized protocol. It is hoped that transplanting non Th2- polarized T-cells and the use of a lower T-cell dose will delay the time until full donor T-cell engraftment occurs lowering the incidence of cGVHD. The inability to find a suitable HLA matched donor limits the application of allogeneic transplantation to only a minority of patients with severe aplastic anemia or RA MDS. For such patients, transplantation using unrelated cord blood (UCB) has been shown to be a reasonable alternative transplant strategy. The major disadvantage of UCB transplantation in adults is the limited number of nucleated cells contained within the cord unit resulting in prolonged neutropenia and failure of engraftment which contributes to infection and TRM. In order to harness the advantage of UCB availability and to overcome the disadvantage of delayed neutrophil recovery, we have recently initiated a clinical trial that evaluates the co-administration of unrelated umbilical cord blood and a relatively low number of highly purified haploidentical peripheral blood CD34+ cells from a related donor as a method to promote rapid neutrophil recovery. Subjects receive a novel non-myeloablative immunosuppressive conditioning regimen followed by an infusion of the allografts. The haploidentical stem cell product is T-cell depleted and enriched for CD34+ cells using the Miltenyi CliniMacs system. To reduce TRM secondary to prolonged neutropenia associated with conventional UCB transplantation, haploidentical CD34+ stem cells are co-infused with a single UCB unit (serologically matched at d 4/6 HLA loci). The primary endpoint will be cord engraftment (persistent cord derived ANC >500 cells/ul) by day 42. This study has recently opened to accrual. Finally, our group is actively involved in preclinical research investigating methods to expand viral reactive T-cells and NK cells from umbilical cord blood units using a device invented in our lab in collaboration with Mr. Herb Cullis that selectively accesses cryopreserved cord units (the Selective Access to Cryopreserved Samples (SACS) device). Using the SACS apparatus, our lab has developed a method to expand from the 1 ml SACed component of the cord unit viral reactive CTL to EBV, adenovirus, and CMV. Remarkably, the Selective Access to Cryopreserved Samples (SACS) device maintains the integrity, sterility and viability of the non-accessed portion of the remaining cord unit (typically 24 mls) which remains in its frozen state and contains sufficient numbers of viable TNCs to allow for its subsequent use as the primary source of transplanted allogeneic hematopoietic stem cells. This methodology potentially could be used to facilitate a transplant approach in which a single umbilical cord blood unit is transplanted in conjunction with the concomitant infusion of viral reactive CTL generated from the same cord unit.