Long-Term Results Of Autologous Hematopoietic Cell Transplantation For Peripheral T Cell Lymphoma: The Stanford Experience

AbstractThe peripheral T cell lymphomas (PTCL) carry a worse prognosis compared to B cell non-Hodgkin lymphoma. There is no uniform standard therapy for PTCL, and autologous hematopoietic cell transplant (AHCT) is often offered as consolidation in first remission or at relapse because of the poor outcomes with conventional therapy. We conducted a retrospective review of patients who underwent AHCT for PTCL from 1989 to 2006. Fifty-three cases were identified consisting of systemic anaplastic large cell (n = 18), PTCL unspecified (n = 17), angioimmunoblastic (n = 9), nasal type extranodal NK/T (n = 7), hepatosplenic (n = 2), and adult T cell leukemia/lymphoma (n = 1). Fifteen patients were transplanted in first complete or partial response (CR1/PR1), 32 in second or beyond CR or PR (CR2/PR2+), and 11 with primary refractory disease (REF). With a median follow-up was 5 years (range: 1.0-11.5), the 5-year progression-free survival (PFS) and overall survival (OS) were 25% and 48%, respectively. Disease status at AHCT had a significant impact on PFS and OS. The 5-year PFS for patients in CR1/PR1, CR2/PR2+, and REF was 51%, 12%, and 0%, respectively, and the corresponding figures for OS were 76%, 40%, and 30%, respectively. The pretransplant factors that impacted survival were disease status and the number of prior regimens. Histology, age, sex, stage, B symptoms, bone marrow involvement, and duration of first response did not significantly affect PFS or OS. Based on these results, AHCT as consolidation therapy in first complete or partial response may offer a durable survival benefit. However, AHCT with conventional salvage chemotherapy has minimal durable benefit in patients with relapsed or refractory PTCL, and thus novel strategies and/or allogeneic HCT should be more aggressively explored in lieu of AHCT for relapsed/ refractory PTCL

Short-Term Immunosuppression Promotes Engraftment of Embryonic and Induced Pluripotent Stem Cells

SummaryEmbryonic stem cells (ESCs) are an attractive source for tissue regeneration and repair therapies because they can be differentiated into virtually any cell type in the adult body. However, for this approach to succeed, the transplanted ESCs must survive long enough to generate a therapeutic benefit. A major obstacle facing the engraftment of ESCs is transplant rejection by the immune system. Here we show that blocking leukocyte costimulatory molecules permits ESC engraftment. We demonstrate the success of this immunosuppressive therapy for mouse ESCs, human ESCs, mouse induced pluripotent stem cells (iPSCs), human induced pluripotent stem cells, and more differentiated ESC/(iPSCs) derivatives. Additionally, we provide evidence describing the mechanism by which inhibition of costimulatory molecules suppresses T cell activation. This report describes a short-term immunosuppressive approach capable of inducing engraftment of transplanted ESCs and iPSCs, providing a significant improvement in our mechanistic understanding of the critical role costimulatory molecules play in leukocyte activation

Indirect Impact of PD-1/PD-L1 Blockade on a Murine Model of NK Cell Exhaustion

The induction of exhaustion on effector immune cells is an important limiting factor for cancer immunotherapy efficacy as these cells undergo a hierarchical loss of proliferation and cytolytic activity due to chronic stimulation. Targeting PD-1 has shown unprecedented clinical benefits for many cancers, which have been attributed to the prevention of immune suppression and exhaustion with enhanced anti-tumor responses. In this study, we sought to evaluate the role of the PD-1/PD-L1 pathway in murine natural killer (NK) cell activation, function, and exhaustion. In an in vivo IL-2-dependent exhaustion mouse model, neutralization of the PD-1/PD-L1 pathway improved NK cell activation after chronic stimulation when compared to control-treated mice. These cells displayed higher proliferative capabilities and enhanced granzyme B production. However, the blockade of these molecules during long-term in vitro IL-2 stimulation did not alter the progression of NK cell exhaustion (NCE), suggesting an indirect involvement of PD-1/PD-L1 on NCE. Given the expansion of CD8 T cells and regulatory T cells (Tregs) observed upon acute and chronic stimulation with IL-2, either of these two populations could influence NK cell homeostasis after PD-L1/PD-1 therapy. Importantly, CD8 T cell activation and functional phenotype were indeed enhanced by PD-1/PD-L1 therapy, particularly with anti-PD-1 treatment that resulted in the highest upregulation of CD25 during chronic stimulation and granted an advantage for IL-2 over NK cells. These results indicate a competition for resources between NK and CD8 T cells that arguably delays the onset of NCE rather than improving its activation during chronic stimulation. Supporting this notion, the depletion of CD8 T cells reversed the benefits of PD-1 therapy on chronically stimulated NK cells. These data suggest a bystander effect of anti-PD1 on NK cells, resulting from the global competition that exists between NK and CD8 T cells for IL-2 as a key regulator of these cells’ activation. Thus, achieving an equilibrium between these immune cells might be important to accomplish long-term efficacy during anti-PD-1/IL-2 therapy

High-Dose Carmustine, Etoposide, and Cyclophosphamide Followed by Allogeneic Hematopoietic Cell Transplantation for Non-Hodgkin Lymphoma

AbstractAllogeneic hematopoietic cell transplantation (HCT) has been shown to be curative in a group of patients with aggressive non-Hodgkin lymphoma (NHL). A previous study has demonstrated equivalent outcomes with a conditioning regimen based on total body irradiation and another not based on total body irradiation with preparative therapy using cyclophosphamide, carmustine, and etoposide (CBV) in autologous HCT. We investigated the safety and efficacy of using CBV in an allogeneic setting. Patients were required to have relapsed or be at high risk for subsequent relapse of NHL. All patients had a fully HLA-matched sibling donor. Patients received carmustine (15 mg/kg), etoposide (60 mg/kg), and cyclophosphamide (100 mg/kg) on days −6, −4, and −2, respectively, followed by allogeneic HCT. All patients were treated with cyclosporine and methylprednisolone as prophylaxis for graft-versus-host disease (GVHD). Thirty-one patients (median age, 46 years) who were felt to be inappropriate candidates for autologous transplantation were enrolled. Each subject had a median of 3 previous chemotherapy regimens. All patients engrafted. Fifteen of 31 patients are alive. Median follow-up time was 11.5 months (range, .4-126). There were 8 deaths due to relapse. Nonrelapse mortality (n = 8) included infection (n = 3), GVHD (n = 2), diffuse alveolar hemorrhage (n = 1), veno-occlusive disease in the setting of concurrent acute GVHD of the liver (n = 1), and leukoencephalopathy (n = 1). Probabilities of event-free survival and overall survival were, respectively, 44% (95% confidence interval, 26%-62%) and 51% (33%-69%) at 1 year and 44% (26%-62%) and 47% (29%-65%) at 5 years. Probability of relapse was 33% (15%-51%) at 1 year and 5 years. Probability of nonrelapse mortality was 31% (13%-49%) at 1 year and 5 years. Incidences were 29% for acute GVHD and 39% for chronic GVHD. None of the 12 patients who developed chronic GVHD has disease recurrence. Patients who had required >3 previous chemotherapy regimens before HCT had an increased probability of relapse. CBV is an effective preparative regimen for patients with aggressive NHL who undergo allogeneic HCT

Cytomegalovirus Viral Load and Virus-Specific Immune Reconstitution after Peripheral Blood Stem Cell versus Bone Marrow Transplantation

Peripheral blood stem cell (PBSC) products contain more T cells and monocytes when compared with bone marrow (BM), leading to fewer bacterial and fungal infections. Cytomegelovirus (CMV) viral load and disease as well as CMV-specific immune reconstitution were compared in patients enrolled in a randomized trial comparing PSBC and BM transplantation. There was a higher rate of CMV infection and disease during the first 100 days after transplantation among PBSC recipients (any antigenemia/DNAemia: PBSC, 63% vs BM, 42%, P = .04; CMV disease: PBSC, 17% vs BM, 4%, P = .03). By 2 years, CMV disease rates were similar. The early increase in CMV events correlated temporarily with lower CMV-specific CD4+ T helper and CD8+ cytotoxic T lymphocyte function at 30 days after transplantation in PBSC recipients. By 3 months after transplantation and thereafter, CMV-specific immune responses were similar between BM and PBSC recipients. In conclusion, higher CMV infection and disease rates occurred in PBSC transplant recipients early after transplantation. These differences may be because of a transient delay in CMV-specific immune reconstitution following PBSC transplantation

Adoptive Immunotherapy with Cytokine-Induced Killer Cells for Patients with Relapsed Hematologic Malignancies after Allogeneic Hematopoietic Cell Transplantation

Donor leukocyte infusions induce remissions in some patients with hematologic malignancies who relapse after allogeneic hematopoietic cell transplantation (HCT); however, graft-versus-host disease (GVHD) remains the major complication of this strategy. Cytokine-induced killer (CIK) cells are a unique population of cytotoxic T lymphocytes that express the CD3+CD56+ phenotype and show marked up-regulation of the natural killer cell receptor NKG2D (CD314). CIK cells are non–major histocompatibility complex–restricted and NKG2D-dependent in target recognition and cytotoxicity. We explored the feasibility of ex vivo expansion of allogeneic CIK cells in patients with relapsed hematologic malignancies after allogeneic HCT. Eighteen patients (median age, 53 years; range, 20-69 years) received CIK cell infusions at escalating doses of 1 × 107 CD3+ cells/kg (n = 4), 5 × 107 CD3+ cells/kg (n = 6), and 1 × 108 CD3+ cells/kg (n = 8). The median expansion of CD3+ cells was 12-fold (range, 4- to 91-fold). CD3+CD56+ cells represented a median of 11% (range, 4%-44%) of the harvested cells, with a median 31-fold (range, 7- to 515-fold) expansion. Median CD3+CD314+ cell expression was 53% (range, 32%-78%) of harvested cells. Significant cytotoxicity was demonstrated in vitro against a panel of human tumor cell lines. Acute GVHD grade I-II was seen in 2 patients, and 1 patient had limited chronic GVHD. After a median follow-up of 20 months (range, 1-69 months) from CIK infusion, the median overall survival was 28 months, and the median event-free survival was 4 months. All deaths were due to relapsed disease; however, 5 patients had longer remissions after infusion of CIK cells than from allogeneic HCT to relapse. Our findings indicate that this form of adoptive immunotherapy is well tolerated and induces a low incidence of GVHD, supporting further investigation as an upfront modality to enhance graft-versus-tumor responses in high-risk patient populations

Foxp3+ regulatory T cells maintain the bone marrow microenvironment for B cell lymphopoiesis

Foxp3+ regulatory T cells (Treg cells) modulate the immune system and maintain self-tolerance, but whether they affect haematopoiesis or haematopoietic stem cell (HSC)-mediated reconstitution after transplantation is unclear. Here we show that B-cell lymphopoiesis is impaired in Treg-depleted mice, yet this reduced B-cell lymphopoiesis is rescued by adoptive transfer of affected HSCs or bone marrow cells into Treg-competent recipients. B-cell reconstitution is abrogated in both syngeneic and allogeneic transplantation using Treg-depleted mice as recipients. Treg cells can control physiological IL-7 production that is indispensable for normal B-cell lymphopoiesis and is mainly sustained by a subpopulation of ICAM1+ perivascular stromal cells. Our study demonstrates that Treg cells are important for B-cell differentiation from HSCs by maintaining immunological homoeostasis in the bone marrow microenvironment, both in physiological conditions and after bone marrow transplantation

Natural Killer Cells in Graft-versus-Host-Disease after Allogeneic Hematopoietic Cell Transplantation

Allogeneic hematopoietic cell transplantation (HCT) is a well-established therapeutic modality effective for a variety of hematological malignancies but, unfortunately, is associated with significant morbidity and mortality related to cancer relapse as well as to transplant-related complications including graft-versus-host-disease (GvHD). Natural killer (NK) cells are the first donor-derived lymphocyte subset to recover after HCT, and their crucial role in protection against cancer relapse and infections is well established. Conversely, the role played by NK cells in GvHD is still controversial. Early studies suggested a participation of NK cells in GvHD induction or exacerbation. Subsequently, experimental evidence obtained in mice as well observational studies performed in humans led to a model in which NK cells play a regulatory role in GvHD by repressing alloreactive T cell responses. This widely accepted model has been recently challenged by clinical evidence indicating that NK cells can in some cases promote GvHD. In this review, we summarize available knowledge about the role of NK cells in GVHD pathogenesis. We review studies uncovering cellular mechanisms through which NK cells interact with other immune cell subsets during GvHD leading to a model in which NK cells naturally suppress GvHD through their cytotoxic ability to inhibit T cell activation unless exogenous hyperactivation lead them to produce proinflammatory cytokines that can conversely sustain T cell-mediated GvHD induction