Autologous Graft-versus-Tumor Effect: Reality or Fiction?

Herpesvirus Screening in Childhood Hematopoietic Transplant Reveals High Systemic Inflammation in Episodes of Multiple Viral Detection and an EBV Association with Elevated IL-1β, IL-8 and Graft-Versus-Host Disease

Infections remain a major cause of morbidity and mortality among hematopoietic stem cell transplant (HSCT) recipients. Unlike Epstein–Barr Virus (EBV) and Human Cytomegalovirus (HCMV), Human Herpesvirus (HHV) 6, HHV7 and HHV8 are not routinely monitored in many centers, especially in the pediatric population of low–medium income countries. We screened EBV, HCMV, HHV6, HHV7 and HHV8 in 412 leukocytes-plasma paired samples from 40 pediatric patients assisted in a tertiary hospital in Mexico. Thirty-two underwent allo-HSCT, whereas eight received auto-HSCT. Overall viral detection frequencies in allo- and auto-HSCT were: EBV = 43.7% and 30.0%, HCMV = 5.0% and 6.7%, HHV6 = 7.9% and 20.0% and HHV7 = 9.7% and 23.3%. HHV8 was not detected in any sample. Interestingly, HHV6 and HHV7 were more frequent in auto-HSCT, and HHV6 was observed in all episodes of multiple detection in auto-HSCT patients. We found EBV DNA in plasma samples, whereas HCMV, HHV6 and HHV7 DNA were predominantly observed in leukocytes, indicative of their expansion in cellular compartments. We also found that IL-1β, IL-2, IL-6 and IL-8 were significantly increased in episodes in which multiple viruses were simultaneously detected, and samples positive for EBV DNA and graft-versus-host disease had a further increase of IL-1β and IL-8. In conclusion, the EBV, HCMV, HHV6 and HHV7 burdens were frequently detected in allo- and auto-HSCT, and their presence associated with systemic inflammation.

The Role of T Cell Immunity in Monoclonal Gammopathy and Multiple Myeloma: From Immunopathogenesis to Novel Therapeutic Approaches

Multiple Myeloma (MM) is a malignant growth of clonal plasma cells, typically arising from asymptomatic precursor conditions, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). Profound immunological dysfunctions and cytokine deregulation are known to characterize the evolution of the disease, allowing immune escape and proliferation of neoplastic plasma cells. In the past decades, several studies have shown that the immune system can recognize MGUS and MM clonal cells, suggesting that anti-myeloma T cell immunity could be harnessed for therapeutic purposes. In line with this notion, chimeric antigen receptor T cell (CAR-T) therapy is emerging as a novel treatment in MM, especially in the relapsed/refractory disease setting. In this review, we focus on the pivotal contribution of T cell impairment in the immunopathogenesis of plasma cell dyscrasias and, in particular, in the disease progression from MGUS to SMM and MM, highlighting the potentials of T cell-based immunotherapeutic approaches in these settings.

Long-term outcome of immunologic autograft engineering

Our phase III trial reported that autograft-absolute lymphocyte count (A-ALC) improved survival post-autologous peripheral blood hematopoietic stem cell transplantation (APBHSCT) for a short-term follow-up of 2 years. We evaluated retrospectively in our phase III trial patients that the A-ALC still confers survival benefit with a longer follow-up. With a median follow-up of 127.6 months, patients infused with an A-ALC ≥ 0.5 × 10⁹ cells/kg experienced better overall survival (HR = 0.392, 95% confidence of interval [CI]: 0.224-0.687, p < 0.001) and progression-free survival (HR = 0.413, 95% CI: 0.253-0.677), p < 0.0004). This study supports that A-ALC provides long-term survival benefit post APBHSCT.

Anti-CD19 and anti-BCMA CAR T cell therapy followed by lenalidomide maintenance after autologous stem-cell transplantation for high-risk newly diagnosed multiple myeloma

Few prospective studies have examined posttransplant chimeric antigen receptor (CAR) T cell infusion as candidates for front-line consolidation therapy for high-risk multiple myeloma (MM) patients. This single-arm exploratory clinical trial is the first to evaluate the safety and efficacy of sequential anti-CD19 and anti-BCMA CAR-T cell infusion, followed by lenalidomide maintenance after autologous stem cell transplantation (ASCT), in 10 high-risk newly diagnosed multiple myeloma (NDMM) patients. The treatment was generally well tolerated, with hematologic toxicities being the most common grade 3 or higher adverse events. All patients had cytokine release syndrome (CRS), which was grade 1 in 5 patients (50%) and grade 2 in 5 patients (50%). No neurotoxicity was observed after CAR-T cell infusion. The overall response rate was 100%, with the best response being 90% for a stringent complete response (sCR), and 10% for a complete response (CR). At a median follow-up of 42 (36-49) months, seven (70%) of 10 patients showed sustained minimal residual disease (MRD) negativity for more than 2 years. The median progression-free survival (PFS) and overall survival (OS) were not reached. Although the sample size was small and there was a lack of control in this single-arm study, the clinical benefits observed warrant ongoing randomized controlled trials.

Infused Autograft Absolute Lymphocyte Count Predicts Superior Survival in Diffuse Large B Cell Lymphoma Patients Post-Autologous Peripheral Blood Hematopoietic Stem Cell Transplantation: A Matched Case-Control Study

Our group published a double phase III trial showing that patients infused with an autograft absolute lymphocyte count (A-ALC) ≥0.5 × 10⁹ cells/kg experienced superior survival post-autologous peripheral blood hematopoietic stem cell transplantation (APBHSCT). Based on the results from our phase III study, as well as published retrospective studies, on April 1, 2017, our Bone Marrow Transplant Program changed our standard practice to collect an A-ALC ≥0.5 × 10⁹ cells/kg in addition to stem cells for lymphoma patients undergoing APBHSCT. The primary objective of the present study was to continue to assess the prognostic ability of A-ALC by evaluating overall survival (OS) and progression-free survival (PFS) of diffuse large B cell lymphoma (DLBCL) patients who underwent APBHSCT after April 1, 2017, compared with matched control groups at a 1:1:1 ratio with DLBCL patients infused with an A-ALC <0.5 × 10⁹ cells/kg and A-ALC ≥0.5 × 10⁹ cells/kg before April 1, 2017. Using the GREEDY algorithm, 85 DLBCL patients (cases) infused with an A-ALC ≥0.5 × 10⁹ cells/kg after April 1, 2017, were matched at a 1:1:1 ratio with control groups of DLBCL patients who underwent transplantation before April 1, 2017: patients infused with an A-ALC <0.5 × 10⁹ cells/kg (control 1) and patients infused with an A-ALC ≥0.5 × 10⁹ cells/kg (control 2) before April 1, 2017. Groups were matched in terms of sex, age, stage, lactate dehydrogenase (LDH) level, performance status, extranodal disease, International Prognostic Index (IPI), and disease status before APBHSCT (complete or partial response). Survival follow-up was truncated at 3 years from the date of transplantation. Cases, control 1, and control 2 were balanced as to age (P = .8), sex (P = .9), LDH (P = .6), performance status (P = .5), extranodal disease (P = .2), IPI (P = .6), and disease status before APBHSCT (P = .2). Cases and control 2 showed superior OS and PFS compared with control 1. Multivariate analysis including all patients continued to show A-ALC ≥0.5 × 10⁹ cells/kg as an independent predictor for OS (hazard ratio [HR], 0.382; 95% confidence interval [CI], 0.241 to 0.605; P < .0001) and PFS (HR, 0.437; 95% CI, 0.279 to 0.629; P < .0001). Our matched case-control study supports the results of previously published retrospective studies and our phase III study showing that the infusion of A-ALC is a prognostic factor for survival in DLBCL patients undergoing APBHSCT. Our findings support the practice of collecting not only enough stem cells for hematologic engraftment, but also enough immune effector cells (ie, A-ALC) to improve clinical outcomes in DLBCL patients post-APBHSCT.

Autograft cellular composition and outcome in myeloma patients: Results of the prospective multicenter GOA study

BACKGROUND

Autologous stem cell transplantation (auto-SCT) is a widely used treatment option in multiple myeloma (MM) patients. The optimal graft cellular composition is not known.

STUDY DESIGN AND METHODS

Autograft cellular composition was analyzed after freezing by flow cytometry in 127 MM patients participating in a prospective multicenter study. The impact of graft cellular composition on hematologic recovery and outcome after auto-SCT was evaluated.

RESULTS

A higher graft CD34⁺ cell content predicted faster platelet recovery after auto-SCT in both the short and long term. In patients with standard-risk cytogenetics, a higher graft CD34⁺ count (>2.5 × 10⁶ /kg) was linked with shorter progression-free survival (PFS; 28 vs. 46 months, p = 0.04), but there was no difference in overall survival (OS) (p = 0.53). In a multivariate model, a higher graft CD34⁺ CD133⁺ CD38^- (>0.065 × 10⁶ /kg, p = 0.009) and NK cell count (>2.5 × 10⁶ /kg, p = 0.026), lenalidomide maintenance and standard-risk cytogenetics predicted better PFS. In contrast, a higher CD34⁺ count (>2.5 × 10⁶ /kg, p = 0.015) predicted worse PFS. A very low CD3⁺ cell count (≤20 × 10⁶ /kg, p = 0.001) in the infused graft and high-risk cytogenetics remained predictive of worse OS.

CONCLUSIONS

Autograft cellular composition may impact outcome in MM patients after auto-SCT. More studies are needed to define optimal graft composition.

STING and transplantation: can targeting this pathway improve outcomes?

Stimulator of interferon genes (STING) is an innate immune sensor of cytoplasmic dsDNA originating from microorganisms and host cells. STING plays an important role in the regulation of murine graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and may be similarly activated during other transplantation modalities. In this review, we discuss STING in allo-HSCT and its prospective involvement in autologous HSCT (auto-HSCT) and solid organ transplantation (SOT), highlighting its unique role in nonhematopoietic, hematopoietic, and malignant cell types.

Human NK Cells in Autologous Hematopoietic Stem Cell Transplantation for Cancer Treatment

Simple Summary

Natural killer (NK) cells are key elements of the innate immune system that have the ability to kill transformed (tumor and virus-infected) cells without prior sensitization. Hematopoietic stem cell transplantation (HSCT) is a medical procedure used in the treatment of a variety of cancers. The early reconstitution of NK cells after HSCT and their functions support the therapeutic potential of these cells in allogenic HSCT. However, the role of NK cells in autologous HSCT is less clear. In this review, we have summarized general aspects of NK cell biology. In addition, we have also reviewed factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells.

Abstract

Natural killer (NK) cells are phenotypically and functionally diverse lymphocytes with the ability to recognize and kill malignant cells without prior sensitization, and therefore, they have a relevant role in tumor immunosurveillance. NK cells constitute the main lymphocyte subset in peripheral blood in the first week after hematopoietic stem cell transplantation (HSCT). Although the role that NK cells play in allogenic HSCT settings has been documented for years, their significance and beneficial effects associated with the outcome after autologous HSCT are less recognized. In this review, we have summarized fundamental aspects of NK cell biology, such as, NK cell subset diversity, their effector functions, and differentiation. Moreover, we have reviewed the factors that affect autologous HSCT outcome, with particular attention to the role played by NK cells and their receptor repertoire in this regard.

CD34+ cell mobilization, blood graft composition, and posttransplant recovery in myeloma patients compared to non-Hodgkin's lymphoma patients: results of the prospective multicenter GOA study

BACKGROUND

Autologous stem cell transplantation is an established treatment option for patients with multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL).

STUDY DESIGN AND METHODS

In this prospective multicenter study, 147 patients with MM were compared with 136 patients with NHL regarding the mobilization and apheresis of blood CD34+ cells, cellular composition of infused blood grafts, posttransplant recovery, and outcome.

RESULTS

Multiple myeloma patients mobilized CD34+ cells more effectively (6.3 × 10⁶ /kg vs. 3.9 × 10⁶ /kg, p = 0.001). The proportion of poor mobilizers (peak blood CD34+ cell count <20 × 10⁶ /L) was higher in NHL patients (15% vs. 3%, p < 0.001). Plerixafor was added to rescue the mobilization failure in 17 MM patients (12%) and in 35 NHL patients (26%; p = 0.002). The infused grafts contained more natural killer (NK) and CD19+ cells in MM patients. Blood platelet and NK-cell counts were higher in MM patients posttransplant. Early treatment-related mortality was low in both groups, but NHL patients had a higher late (>100 days) nonrelapse mortality (NRM; 6% vs. 0%, p = 0.003).

CONCLUSIONS

Non-Hodgkin's lymphoma and MM patients differ in terms of mobilization of CD34+ cells, graft cellular composition, and posttransplant recovery. Thus, the optimal graft characteristics may also be different.

Combined immune score of lymphocyte to monocyte ratio and immunoglobulin levels predicts treatment-free survival of multiple myeloma patients after autologous stem cell transplant

Outcomes after ASCT are highly variable making it difficult to predict risk of disease progression. We analyzed the impact of clinically available immune-related biomarkers on treatment-free survival (TFS) in 130 patients receiving Mel200 and ASCT. Absolute lymphocyte count (ALC), monocyte count (AMC), neutrophil count (ANC), and immunoglobulin (Ig) levels were collected on day -2 and 90 of ASCT. The lymphocyte-monocyte (LMR) and neutrophil-lymphocyte ratios (NLR) were then derived. At Day +90, we found that low ALC (18 versus 23 months, p = 0.04) or AMC (13 versus 25 months, p = 0.02) predicted for worse TFS. A low LMR predicted for worse TFS (16 versus 52 months, p = 0.004). Patients with two or three suppressed Ig levels had worse TFS (17 versus 51 months, p = 0.04). Median TFS for poor (low LMR and 2-3 suppressed Ig), intermediate, and good (high LMR and 0-1 suppressed Ig) risk groups was 7.5 versus 27 versus 79 months, respectively (p = 0.0004). In a multivariate analysis, a low LMR and suppressed Ig levels were strong independent predictors of poor TFS. We propose an immune score combining these available tests to stratify patients at risk for early progression and identify those who may benefit from intensified post-ASCT consolidation or immunotherapy based approaches.

Pre-immunization of donor lymphocytes with GITR agonistic antibody enhances antitumor immunity in autologous hematopoietic stem cell transplantation

The lymphopenic condition following autologous hematopoietic stem cell transplantation (HSCT) enhances the proliferation of T cells by engaging tumor-associated antigens, leading to the alteration of the T-cell repertoire towards antitumor immunity. However, cure by autologous HSCT alone have rarely occurred in the clinical setting. Since tumor-reactive lymphocytes preferentially proliferate during reconstitution of the immune system, we examined whether the priming of donor lymphocytes can strengthen the antitumor effect by HSCT in a CT26 murine colon cancer model. The systemic administration of an anti-glucocorticoid-induced TNF receptor (GITR) agonistic antibody (Ab) significantly increased the number of CT26-responsive T cells but not that of auto-reactive lymphocytes in donor mice. The infusion of non-primed and GITR Ab-primed donor lymphocytes suppressed the CT26 tumor growth, and only the primed lymphocytes eliminated tumors in all the treated mice. The frequency of CT26-responsive T cells was elevated in recipient mice infused with both primed and non-primed lymphocytes until 4 weeks after transplantation, while the frequency in recipients with primed lymphocytes was markedly elevated compared with that in mice harboring non-primed lymphocytes at 2 weeks. The frequencies of regulatory T cells and myeloid-derived suppressor cells were elevated in recipient mice infused with primed and non-primed lymphocytes 2 weeks after transplantation, and returned to normal levels by week 4. The combination of autologous HSCT with pre-immunization of donor lymphocytes is a promising strategy to induce strong antitumor immunity.

Autologous graft versus myeloma: it's not a myth

Graft-versus-tumor (GVT) effects have been thought to mostly result from allogeneic transplants; however, there is a growing body of research that supports a possible autologous GVT effect. In early clinical studies, a positive correlation between lymphocyte count recovery after autologous transplantation and overall survival has been observed. However, mechanistic studies to identify the mediators of autologous GVT responses have been lacking. In this issue of the JCI, Vuckovic et al. observed a T cell-dependent autologous GVT effect in the Vk*MYC myeloma model. Moreover, the authors showed that CD8+ T cells mediate myeloma control through IFN-γ secretion, which could be further augmented with a CD137 agonist, suggesting a therapeutic approach for enhancing autologous GVT.

Absolute lymphocyte counts at end of induction correlate with distinct immune cell compartments in pediatric B cell precursor acute lymphoblastic leukemia

Several retrospective studies in children with B cell precursor (BCP) acute lymphoblastic leukemia (ALL) provided clinical evidence that higher absolute lymphocyte counts (ALC) early into treatment significantly correlated with improved relapse-free and overall survival. It still remains unknown, however, whether the predictive role of higher ALCs reflects general bone marrow recovery or a more specific attribute of immune function. To investigate this question, we implemented a prospective observational cohort study in 20 children with BCP ALL on day 29 (D29) of induction chemotherapy and immunophenotyped their lymphoid (T, B and natural killer cells) and myeloid (neutrophils, monocytes, dendritic cells) compartments. In a first evaluation of a cohort treated with Children's Oncology Group-based induction chemotherapy, the immune cell compartments were differentially depleted at D29. Neither gender, risk status, minimal residual disease, nor bone marrow recovery markers correlated with D29 ALC. In contrast, both CD3+ T cell and dendritic cell compartments, which did not correlate with age, significantly correlated with D29 ALC (p < 0.0001). In addition, subset complexity of cellular immune compartments was preserved at D29. This study reveals that D29 ALC significantly correlates with distinct immune cell compartments but not with bone marrow recovery markers, suggesting that higher D29 ALCs may contribute to leukemia control by inducing specific host immune activity.

Infusion of autograft natural killer cell/CD14+HLA-DRDIM cell ratio predicts survival in lymphoma post autologous stem cell transplantation

The infusion of autograft absolute lymphocyte count (A-ALC) and autograft natural killer cells (A-NKC) are prognostic factors for overall survival (OS) and PFS in non-Hodgkin's lymphoma (NHL) patients undergoing autologous peripheral blood hematopoietic stem cell transplantation (APBHSCT). The human monocytic CD14⁺HLA-DR^DIM cells are associated with worse prognosis in NHL. Thus, we investigated whether the autograft A-NKC/A-CD14⁺HLA-DR^DIM ratio predicts survival in NHL. In a total of 111 NHL patients, we analyzed apheresis collection samples for the content of A-NKC and A-CD14⁺HLA-DR^DIM. With a median follow-up of 57.2 months (range: 2.1-84.6 months), patients with an A-NKC/A-CD14⁺HLA-DR^DIM ratio of ⩾0.29 experienced superior OS (5-year OS rates of 84% (95% confidence interval (CI), 72-91%) vs 48% (95% CI, 34-62%), P<0.0002, respectively) and PFS (5-year PFS rates of 59% (95% CI, 47-71%) vs 32% (95% CI, 20-48%), P<0.002, respectively). Multivariate analysis revealed that A-NKC/A-CD14⁺HLA-DR^DIM ratio was an independent predictor for PFS (hazard ratio (HR)=0.56, 95% CI, 0.32-0.96, P<0.03) and OS (HR=0.34, 95% CI, 0.16-0.68, P<0.002). The A-NKC/A-CD14⁺HLA-DR^DIM ratio provides a platform to target specific autograft immune effector cells to improve clinical outcomes in NHL patients undergoing APBHSCT.

Preemptive plerixafor injection added to pegfilgrastim after chemotherapy in non-Hodgkin lymphoma patients mobilizing poorly

Filgrastim is usually combined with chemotherapy to mobilize hematopoietic progenitor cells in non-Hodgkin lymphoma (NHL) patients. Limited information is available on the efficacy of a preemptive plerixafor (PLER) injection in poor mobilizers after chemotherapy and pegfilgrastim. In this prospective study, 72 patients with NHL received chemotherapy plus pegfilgrastim, and 25 hard-to-mobilize patients received also PLER. The usefulness and efficacy of our previously developed algorithm for PLER use in pegfilgrastim-containing mobilization regimen were evaluated as well as the graft cellular composition, hematological recovery, and outcome after autologous stem cell transplantation (auto-SCT) according to the PLER use. A median 3.4-fold increase in blood CD34⁺ cell counts was achieved after the first PLER dose. The minimum collection target was achieved in the first mobilization attempt in 66/72 patients (92%) and 68 patients (94%) proceeded to auto-SCT. An algorithm for PLER use was fulfilled in 76% of the poor mobilizers. Absolute numbers of T-lymphocytes and NK cells were significantly higher in the PLER group, whereas the number of CD34⁺ cells collected was significantly lower. Early neutrophil engraftment was slower in the PLER group, otherwise hematological recovery was comparable within 12 months from auto-SCT. No difference was observed in survival according to the PLER use. Chemotherapy plus pegfilgrastim combined with preemptive PLER injection is an effective and convenient approach to minimize collection failures in NHL patients intended for auto-SCT. A significant effect of PLER on the graft cellular composition was observed, but no difference in outcome after auto-SCT was detected.

The Complexity of Targeting PI3K-Akt-mTOR Signalling in Human Acute Myeloid Leukaemia: The Importance of Leukemic Cell Heterogeneity, Neighbouring Mesenchymal Stem Cells and Immunocompetent Cells

Therapeutic targeting of PI3K-Akt-mTOR is considered a possible strategy in human acute myeloid leukaemia (AML); the most important rationale being the proapoptotic and antiproliferative effects of direct PI3K/mTOR inhibition observed in experimental studies of human AML cells. However, AML is a heterogeneous disease and these effects caused by direct pathway inhibition in the leukemic cells are observed only for a subset of patients. Furthermore, the final effect of PI3K-Akt-mTOR inhibition is modulated by indirect effects, i.e., treatment effects on AML-supporting non-leukemic bone marrow cells. In this article we focus on the effects of this treatment on mesenchymal stem cells (MSCs) and monocytes/macrophages; both these cell types are parts of the haematopoietic stem cell niches in the bone marrow. MSCs have unique membrane molecule and constitutive cytokine release profiles, and mediate their support through bidirectional crosstalk involving both cell-cell contact and the local cytokine network. It is not known how various forms of PI3K-Akt-mTOR targeting alter the molecular mechanisms of this crosstalk. The effect on monocytes/macrophages is also difficult to predict and depends on the targeted molecule. Thus, further development of PI3K-Akt-mTOR targeting into a clinical strategy requires detailed molecular studies in well-characterized experimental models combined with careful clinical studies, to identify patient subsets that are likely to respond to this treatment.