Modulating microbiome-immune axis in the deployment-related chronic diseases of Veterans: report of an expert meeting.

The present report summarizes the United States Department of Veterans Affairs (VA) field-based meeting titled "Modulating microbiome-immune axis in the deployment-related chronic diseases of Veterans." Our Veteran patient population experiences a high incidence of service-related chronic physical and mental health problems, such as infection, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), various forms of hematological and non-hematological malignancies, neurologic conditions, end-stage organ failure, requiring transplantation, and posttraumatic stress disorder (PTSD). We report the views of a group of scientists who focus on the current state of scientific knowledge elucidating the mechanisms underlying the aforementioned disorders, novel therapeutic targets, and development of new approaches for clinical intervention. In conclusion, we dovetailed on four research areas of interest: 1) microbiome interaction with immune cells after hematopoietic cell and/or solid organ transplantation, graft-versus-host disease (GVHD) and graft rejection, 2) intestinal inflammation and its modification in IBD and cancer, 3) microbiome-neuron-immunity interplay in mental and physical health, and 4) microbiome-micronutrient-immune interactions during homeostasis and infectious diseases. At this VA field-based meeting, we proposed to explore a multi-disciplinary, multi-institutional, collaborative strategy to initiate a roadmap, specifically focusing on host microbiome-immune interactions among those with service-related chronic diseases to potentially identify novel and translatable therapeutic targets.

Overview of approved CAR-T therapies, ongoing clinical trials, and its impact on clinical practice.

In recent years, we have seen rapid expansion of chimeric antigen receptor T-cell (CAR-T) therapies in multiple malignancies. CAR-T therapy has profoundly altered the treatment landscape of non-Hodgkin lymphoma, B-cell acute lymphoblastic leukemia, and multiple myeloma. Currently available CD19 and B-cell maturation antigen-directed CAR-T therapies have shown high overall response rate and durable remissions in patients who have failed standard therapies. Multiple studies are underway exploring the role of CAR-T-cell therapy as earlier line of treatment. In high-grade B-cell lymphoma, CD19 CAR-T therapy may replace autologous hematopoietic cell transplantation as second line therapy in near future. CAR-T-cell therapy targeting novel tumor-associated antigens will help expand utility of this treatment modality in other hematological malignancies. It may also help overcome limitations of currently approved CAR-T-cell therapies. In this review, we have provided an overview of currently approved CAR-T therapies and upcoming clinical trials which may potentially impact the clinical practice.

Role of bridging therapy during chimeric antigen receptor T cell therapy.

Chimeric antigen receptor (CAR) T-cell therapy has been approved for use in several relapsed/refractory hematologic malignancies and has significantly improved outcomes for these diseases. A number of different CAR T products are now being used in clinical practice and have demonstrated excellent outcomes to those in clinical trials. However, increased real-world use of CAR T therapy has uncovered a number of barriers that can lead to significant delays in treatment. As a result, bridging therapy has become a widely used tool to stabilize or debulk disease between leukapheresis and CAR T cell administration. Here we review the available data regarding bridging therapy, with a focus on patient selection, choice of therapy, timing of therapy, and potential pitfalls.

CAR T cell therapy in solid tumors: A review of current clinical trials.

Chimeric antigen receptor (CAR) T cell therapy has made tremendous strides in the arena of hematological malignancies with approved therapies in certain leukemias, lymphomas, and recently myeloma with overall highly favorable response rates. While numerous clinical studies are still ongoing for hematological malignancies, research is developing to translate the feasibility of CAR T therapy in solid organ malignancies. Unfortunately, the majority of diagnosed cancers are primarily solid tumors. Thus, a highly unmet clinical need for further research and development exists in this field. This review article highlights currently active clinical trials and a few pertinent preclinical studies involving CAR T cell therapy in solid tumors while briefly discussing study outcomes and potential key targets that may allow for the feasibility of this therapy option. Finally, we mention critical challenges existing in the solid tumor environment and discuss developing strategies that may potentially overcome the existing barriers to CAR T cell progress in solid tumors.

Reduction in the Prevalence of Thrombotic Events in Sickle Cell Disease after Allogeneic Hematopoietic Transplantation.

Thrombosis is a recognized complication in sickle cell disease (SCD). Allogeneic hematopoietic cell transplantation (allo-HCT) remains the sole curative option for patients with severe SCD phenotypes. Data describing the effects of allo-HCT on recurrent thrombotic events (venous and arterial events) are limited, however. We evaluated 31 patients with SCD who underwent allo-HCT with a median follow-up of 34.5 months (range, 13 to 115) post-transplantation. No patient continued anticoagulation or antiplatelet therapy after allo-HCT. There was an absolute difference of 32% (95% confidence interval [CI], 12.3% to 32.2%; P = .002) in the prevalence of venous thromboembolic (VTE) events before and after allo-HSCT. In addition, there was an absolute difference of 38.5% (95% CI, 10.63 to 45.96; P = .006) in the number of ischemic cerebrovascular accidents (CVAs) occurring before and after allo-HSCT. Patients with severe SCD who undergo allo-HCT are less likely to develop recurrent thrombotic events compared with a control cohort of patients matched for age and genotype (odds ratio, 0.22; 95% CI, 0.058 to 0.83; P = .025). Following curative therapy with allo-HCT, there is a reduction in recurrent arterial and venous thrombosis in patients with severe SCD phenotypes.

The use of venetoclax-based salvage therapy for post-hematopoietic cell transplantation relapse of acute myeloid leukemia.

For patients with high risk myeloid disease, allogeneic hematopoietic cell transplantation (HCT) is the only potentially curative therapy. Unfortunately, many of these patients relapse after HCT and have a limited survival. The recent approval of venetoclax, an orally bioavailable BCL-2 inhibitor, resulted in significant responses in treatment naïve acute myeloid leukemia (AML), and off-label use in the relapsed/refractory setting is increasing. We report the outcomes of 21 patients who underwent allogeneic HCT for myeloid disease, relapsed with AML, and were treated with venetoclax. Several patients had poor risk features including antecedent hematologic malignancy (6/21), complex karyotype (6/21), and TP53 mutations (5/21). The median age was 64.5 years and time from HCT to relapse was 5.7 months (range: 0.9 to 44.9 months). Of the 19 patients who were assessed for response, there were meaningful treatment responses seen in eight patients: five CR, three CRi, zero PR, for an ORR of 42.1%. Treatment effect was seen in six additional patients, including four in the morphologic leukemia-free state. Nine patients maintained their response for ≥3 months and eight were receiving therapy at data cut. Post-HCT AML relapse has an exceedingly poor outcome, and venetoclax-based therapy is a potent therapy option that should be studied prospectively in this setting.

Minimal residual disease negativity and lenalidomide maintenance therapy are associated with superior survival outcomes in multiple myeloma.

Modern combinations of therapies for multiple myeloma have led to improvement in survival outcomes with near 100% overall response rate and 25% complete response rates, particularly with autologous hematopoietic cell transplant (AHCT). Minimal residual disease (MRD) assessment with multiparameter flow cytometry is a valid prognostic biomarker for progression-free survival (PFS) and overall survival (OS). However, few data exist regarding whether MRD positivity or negativity will meaningfully influence treatment decisions. We evaluated 433 patients who received induction therapy, followed by AHCT. Participants had MRD assessment by multiparameter flow cytometry before and at days +100 and +365 following AHCT. They also received either lenalidomide, bortezomib, or no maintenance therapy following AHCT. Maintenance treatment with lenalidomide improved MRD negativity at day +365 compared to bortezomib (92.9% vs 41.6%, p = 0.01), or no maintenance therapy (92.9% vs 24.4%, p = 0.012). The median PFS for patients who were MRD negative at day + 365 was 42 vs 17.5 months (p < 0.001) and median OS was 80.6 vs 59 months (p = 0.02). Maintenance therapy following AHCT for multiple myeloma improves the depth of response as assessed by MRD.

New-onset post-transplant diabetes mellitus after haploidentical hematopoietic cell transplant with post-transplant cyclophosphamide.

Haploidentical hematopoietic cell transplant (haplo-HCT) with post-transplant cyclophosphamide (PTCY) is utilized for patients with hematological disorders but without conventional donors. The effects of new-onset post-transplant diabetes mellitus (PTDM) following haplo-HCT are unknown. We examined PTDM incidence and outcomes after haplo-HCT with PTCY. Patients without diabetes receiving haplo-HCT (n=64) were analyzed for PTDM diagnosis (defined as blood glucose≥ 200 mg/dL). By day 100, 14 (22%) patients developed PTDM (median, 18 days). Hyperglycemia (blood glucose ≥ 200 mg/dL) preceded corticosteroids in 11 (79%) individuals. PTDM patients had increased death/relapse (p=0.029). PTDM occurs frequently, precedes corticosteroids, and leads to inferior outcomes following haplo-HCT. PTDM prophylaxis/treatment may improve HCT survival.

Conditioning intensity in secondary AML with prior myelodysplastic syndrome/myeloproliferative disorders: an EBMT ALWP study.

Patients with secondary AML (sAML) with antecedent myelodysplastic syndrome (MDS) or myeloproliferative neoplasms (MPNs) tend to have high-risk disease based on the older age of patients, high-risk cytogenetics, and higher number of prior treatments. Allogeneic hematopoietic cell transplant (HCT) is the only potentially curative therapy available. Eight hundred and two adults with sAML and prior MDS/MPN who received a first HCT between 2000 and 2016 were included in the European Society for Blood and Marrow Transplant (EBMT) Acute Leukemia Working Party (ALWP) study. Median age of the cohort was 59.6 years (range, 18.6-78.6 years). Myeloablative conditioning (MAC) was given to 40% of patients, and 60% received reduced-intensity conditioning (RIC). Overall, the 2-year cumulative incidence of relapse (RI) was 37%, leukemia-free survival (LFS) was 40%, overall survival (OS) was 46%, nonrelapse mortality (NRM) was 23%, and chronic graft-versus-host disease (cGVHD) was 39%. In univariate analysis, a statistical difference between conditioning regimens 6 months after HCT in favor of the MAC group was noted with regard to RI (hazard ratio [HR], 1.47; P = .03), LFS (HR, 1.43; P = .01), and OS (HR, 1.55; P < .05). There was no difference in the cumulative incidence of NRM (HR, 1.38; P = .15). This effect was similarly seen in multivariate analysis (MVA): cumulative incidence of relapse (HR, 1.79; P < .05), LFS (HR, 1.43; P = .02), and OS (HR, 1.53; P = .005) with no difference in NRM (HR, 1; P = .98). This EBMT ALWP analysis suggests that long-term survival can be achieved in patients with sAML with antecedent MDS/MPN and that MAC is a suitable conditioning regimen in patients with sAML.

Transplant Outcomes for Secondary Acute Myeloid Leukemia: Acute Leukemia Working Party of the European Society for Blood and Bone Marrow Transplantation Study.

Secondary acute myeloid leukemia (sAML) has been associated with inferior outcomes compared with de novo AML. Little is known about patient risk factors and outcomes in sAML after allogeneic hematopoietic stem cell transplantation (HCT); thus, this large systemic analysis of the European Society for Blood and Bone Marrow Transplantation registry was performed. This study included 4997 patients with sAML who received HCT from 2000 to 2016. In univariate analysis the 2-year cumulative incidence of chronic graft-versus-host disease (GVHD), relapse, and nonrelapse mortality (NRM) were 33.5% (95% confidence interval [CI], 32% to 34.9%), 33.7% (95% CI, 32.3% to 35.1%), and 27.5% (95% CI, 26.1% to 28.7%), respectively. Overall survival (OS), leukemia-free survival (LFS), and GVHD-free, relapse-free survival (GRFS) at 2 years were 44.5% (95% CI, 43% to 46%), 38.8% (95% CI, 37.4% to 40.3%), and 27.2% (95% CI, 25.9% to 28.6%), respectively. In multivariate analysis, patients receiving myeloablative regimens had decreased relapse (hazard ratio, .859; 95% CI, .761 to .97; P = .01), higher NRM (hazard ratio, 1.175; 95% CI, 1.03 to 1.341; P = .02), and no differences in OS, LFS, and GRFS compared with patients receiving reduced-intensity conditioning regimens. Active disease, adverse cytogenetics, older age, Karnofsky performance status (≤80%), ex vivo T cell depletion, other malignant hematologic diseases, and patient cytomegalovirus seropositivity were associated with inferior OS and LFS. These variables should be considered in patients with sAML in need of HCT, and further study regarding the impact of conditioning regimens on relapse is needed.

Lenalidomide vs bortezomib maintenance choice post-autologous hematopoietic cell transplantation for multiple myeloma.

Maintenance therapy post-autologous hematopoietic cell transplantation (AHCT) with either lenalidomide or bortezomib for multiple myeloma (MM) have separately been shown to improve progression-free survival (PFS), but have never been directly compared. We performed a retrospective study to investigate progression-free and overall survival outcomes and toxicities of lenalidomide maintenance therapy compared with bortezomib maintenance in MM patients post-AHCT. This study included 156 patients who received post-AHCT lenalidomide or bortezomib maintenance therapy for MM. The primary outcome was PFS. Ninety-two patients received lenalidomide maintenance and 64 received bortezomib maintenance post-AHCT. By multivariable analysis, maintenance therapy choice and cytogenetics risk did not impact PFS or OS. Staging by International Staging System and pre-maintenance disease response were the greatest predictors for PFS. Treatment-related toxicities were as anticipated with 5.4% of patients receiving maintenance lenalidomide experiencing secondary primary malignancies (SPMs) compared with 3% for bortezomib. These findings suggest there were no differences in PFS or OS between lenalidomide and bortezomib maintenance therapy options for post-transplantation MM patients. These data should be validated in a larger, prospective cohort to determine if maintenance choice should be guided by side effect profile and patient anticipated tolerance rather than by disease biology alone.

Optimizing Antithymocyte Globulin Dosing for Unrelated Donor Allogeneic Hematopoietic Cell Transplantation Based on Recipient Absolute Lymphocyte Count.

Antithymocyte globulin (ATG) is used as prophylaxis against graft-versus-host disease (GVHD). Current dosing regimens for ATG are empiric and weight-based, and do not account for patient-specific factors. Furthermore, the target of ATG, recipient T cells post-cytotoxic chemotherapy, is not a function of recipient weight. We hypothesized the recipient peripheral blood absolute lymphocyte count (ALC) on the day of ATG administration would interact with the dose of ATG administered to predict transplantation outcomes. We retrospectively analyzed 135 patients who received ATG for GVHD prophylaxis for unrelated allogeneic hematopoietic cell transplantation at 3 different doses: 10 mg/kg, 7.5 mg/kg, and 5 mg/kg. There was no difference in 2-year overall survival (OS) among ATG dosing groups; however, deaths from infectious complications were significantly higher with higher doses of ATG (3.7% versus 19% versus 26.7%; P = .02). Severity of chronic GVHD was lower with higher doses of ATG (28% versus 24% versus 4%; P = .03). In multivariate analysis, the median peripheral blood ALC on day of ATG administration and the total amount of ATG interacted to predict OS (hazard ratio, .09; P = .03). For low recipient ALC (10th percentile, or .56 × 102/µL), a higher total ATG dose was associated with a greater risk of death, whereas for high recipient ALC (90th percentile, or 24.96 × 102/µL), a higher ATG dose was associated with a lower risk of death. Our findings suggest that the interaction between ATG and its target, the recipient lymphocyte, could represent a new paradigm for ATG dosing.

Metabolic Complications Precede Alloreactivity and Are Characterized by Changes in Suppression of Tumorigenicity 2 Signaling.

New-onset post-transplantation diabetes mellitus (PTDM) occurs commonly after allogeneic hematopoietic cell transplantation (HCT) and is associated with inferior survival. We hypothesize that PTDM and nonrelapse mortality (NRM) are related to IL-33/suppression of tumorigenicity 2 (ST2) signaling and that soluble ST2 (sST2) levels will predict PTDM diagnosis. sST2 was measured at engraftment and day +30 in 36 euglycemic HCT recipients followed prospectively for PTDM (cohort 1). Results were confirmed in a validation cohort of 26 patients without pre-existing diabetes analyzed retrospectively for PTDM (cohort 2). Twelve patients with established diabetes before HCT were analyzed in cohort 3. When compared with recipients without PTDM, patients developing PTDM (n = 24) from cohort 1 had elevated sST2 levels at engraftment (P = .02) and at day +30 (P < .01). Cohort 2 confirmed this finding at engraftment (P = .01). Cohort 3 patients with pretransplantation diabetes had higher sST2 at engraftment than patients maintaining euglycemia after HCT from cohort 2 (P = .03). Multivariate analysis of cohorts 1 and 2 showed high engraftment sST2 predicted increased PTDM and NRM risk, independent of conditioning and grades 3 to 4 acute graft-versus-host-disease. sST2 was elevated in PTDM, indicating a relationship between glucose homeostasis and the IL-33/ST2 axis after transplantation. Correction of metabolic complications may decrease sST2 and improve NRM.

Reduced-Intensity Conditioning with Fludarabine, Cyclophosphamide, and Rituximab Is Associated with Improved Outcomes Compared with Fludarabine and Busulfan after Allogeneic Stem Cell Transplantation for B Cell Malignancies.

Reduced-intensity conditioning (RIC) has been used increasingly for allogeneic hematopoietic cell transplantation to minimize transplant-related mortality while maintaining the graft-versus-tumor effect. In B cell lymphoid malignancies, reduced-intensity regimens containing rituximab, an antiCD20 antibody, have been associated with favorable survival; however, the long-term outcomes of rituximab-containing versus nonrituximab-containing regimens for allogeneic hematopoietic cell transplantation in B cell lymphoid malignancies remain to be determined. We retrospectively analyzed 94 patients who received an allogeneic transplant for a B cell lymphoid malignancy. Of these, 33 received RIC with fludarabine, cyclophosphamide, and rituximab (FCR) and graft-versus-host disease (GVHD) prophylaxis with a calcineurin inhibitor and mini-methotrexate, and 61 received RIC with fludarabine and busulfan (FluBu) and GVHD prophylaxis with a calcineurin inhibitor and mycophenolate mofetil. The 2-year overall survival was superior in patients who received FCR versus FluBu (72.7% versus 54.1%, P = .031), and in multivariable analysis adjusted for Disease Risk Index and donor type, only the conditioning regimen (FluBu versus FCR: HR, 2.06; 95% CI, 1.04 to 4.08; P = .037) and Disease Risk Index (low versus intermediate/high: HR, .38; 95% CI, .17 to .86; P = .02) were independent predictors of overall survival. The 2-year cumulative incidence of chronic GVHD was lower in patients who received FCR versus FluBu (24.2% versus 51.7%, P = .01). There was no difference in rate of relapse/progression or acute GVHD. Our results demonstrate that the use of RIC with FCR and GVHD prophylaxis with a calcineurin inhibitor and mini-methotrexate is associated with decreased chronic GVHD and improved overall survival.