Flow cytometry of DNMT1 as a biomarker of hypomethylating therapies.

The 5-azacytidine (AZA) and decitabine (DEC) are noncytotoxic, differentiation-inducing therapies approved for treatment of myelodysplastic syndrome, acute myeloid leukemias (AML), and under evaluation as maintenance therapy for AML postallogeneic hematopoietic stem cell transplant and to treat hemoglobinapathies. Malignant cell cytoreduction is thought to occur by S-phase specific depletion of the key epigenetic regulator, DNA methyltransferase 1 (DNMT1) that, in the case of cancers, thereby releases terminal-differentiation programs. DNMT1-targeting can also elevate expression of immune function genes (HLA-DR, MICA, MICB) to stimulate graft versus leukemia effects. In vivo, there is a large inter-individual variability in DEC and 5-AZA activity because of pharmacogenetic factors, and an assay to quantify the molecular pharmacodynamic effect of DNMT1-depletion is a logical step toward individualized or personalized therapy. We developed and analytically validated a flow cytometric assay for DNMT1 epitope levels in blood and bone marrow cell subpopulations defined by immunophenotype and cell cycle state. Wild type (WT) and DNMT1 knock out (DKO) HC116 cells were used to select and optimize a highly specific DNMT1 monoclonal antibody. Methodologic validation of the assay consisted of cytometry and matching immunoblots of HC116-WT and -DKO cells and peripheral blood mononuclear cells; flow cytometry of H116-WT treated with DEC, and patient samples before and after treatment with 5-AZA. Analysis of patient samples demonstrated assay reproducibility, variation in patient DNMT1 levels prior to treatment, and DNMT1 depletion posttherapy. A flow-cytometry assay has been developed that in the research setting of clinical trials can inform studies of DEC or 5-AZA treatment to achieve targeted molecular pharmacodynamic effects and better understand treatment-resistance/failure.

A multicenter study of posttransplantation low-dose inotuzumab ozogamicin to prevent relapse of acute lymphoblastic leukemia.

ABSTRACT: The curative potential of allogeneic hematopoietic transplantation (allo-HCT) in patients with acute lymphoblastic leukemia (ALL) is hampered by relapse. Inotuzumab ozogamicin (INO) is an anti-CD22 monoclonal antibody bound to calicheamicin, which has significant activity against ALL. We hypothesized that low-dose INO would be safe and feasible after allo-HCT. Therefore, we conducted a phase 1 study to determine the dose and safety in this setting. Patients were eligible if they were aged 16 to 75 years, had undergone allo-HCT for CD22+ ALL, were in complete remission (CR) after allo-HCT, had high risk of recurrence, were between day 40 and 100 after allo-HCT with adequate graft function, and did not have a history of sinusoidal obstruction syndrome (SOS). The objectives of this trial were to define INO maximum tolerated dose (MTD), to determine post-allo-HCT INO safety, and to measure 1-year progression-free survival (PFS). The trial design followed a "3+3" model. The treatment consisted of INO given on day 1 of 28-day cycles. Dose levels were 0.3 mg/m2, 0.4 mg/m2, 0.5 mg/m2, and 0.6 mg/m2. Median age was 44 years (range, 17-66 years; n = 18). Disease status at transplantation was first CR (n = 14) or second CR or beyond (n = 4). Preparative regimen was of reduced intensity in 72% of patients who received transplantation. Most common toxicity was thrombocytopenia. There were no instances of SOS; the MTD was 0.6 mg/m2. One-year nonrelapse mortality was 5.6%. With a median follow-up of 18.1 months (range, 8.6-59 months) 1-year post-allo-HCT PFS and overall survival is 89% and 94%, respectively. Low-dose INO has a favorable safety profile and was associated with high rates of 1-year PFS. This trial was registered at www.clinicaltrials.gov as #NCT03104491.

Phase I study of intra-osseous co-transplantation of a single-unit cord blood and mesenchymal stromal cells with reduced intensity conditioning regimens.

Cord blood (CB) is a valuable graft source for patients undergoing allogeneic hematopoietic cell transplant (HCT) who lack human leukocyte antigen (HLA)-matched donors. However, single-unit CB-HCT is limited by the insufficient cell dose and slow engraftment. To overcome these limitations, we combined a single-unit CB with third-party healthy donors' bone marrow (BM) derived mesenchymal stromal cells (MSCs) to improve engraftment and injected intra-osseously (IO) to enhance homing. In this phase I clinical trial, six patients with high-risk hematologic malignancies were enrolled and received allogeneic HCT using reduced intensity conditioning regimens. The primary objective was to determine the engraftment rate at day 42. The median age of enrolled patients was 68 years, and only one patient was in complete remission at the time of HCT. The median CB total nucleated cell dose was 3.2x107/kg. No serious adverse events were reported. Two patients had early deaths due to persistent disease and multi-drug resistant bacterial infection, respectively. Of the remaining four evaluable patients, all had successful neutrophil engraftment in a median of 17.5 days. No grade 3 or higher acute graft-versus-host disease (GvHD) was observed, and only one patient developed moderate-extensive chronic GvHD. In conclusion, IO co-transplantation of a single-unit CB and MSCs was feasible and resulted in a reasonable engraftment rate in these very high-risk patients.

Optimizing the cryopreservation and post-thaw recovery of natural killer cells is critical for the success of off-the-shelf platforms.

Natural killer (NK) cells are a promising allogeneic, off-the-shelf, cellular immunotherapy product. These cells can be manipulated ex vivo, genetically edited to enhance tumor targeting and expanded to produce large cell banks for multiple patient infusions. Therapeutic efficacy of these products depends on the recovery of viable and functional cells post-thaw. Post-thaw loss of viability and cytolytic activity results in large, and often variable, discrepancies between the intended cell dose (based on counts at cryopreservation) and the actual dose administered. Compared to their highly activated state in fresh culture, post-thaw NK cells demonstrate critical changes in cytokine production, cytotoxic activity, in vivo proliferation and migration. When these NK cells are introduced into the highly immunosuppressive tumor microenvironment, the functional changes induced by cryopreservation further limits the clinical potential of these products. This report will review the impact of cryopreservation on ex vivo expanded NK cells and outlines strategies described in published studies to recover post-thaw function.

Nomenclature for Cellular and Genetic Therapies: A Need for Standardization.

As the field of cellular and genetic therapies transitions from a scientific concept to a clinical reality, it has become evident that there are several conflicting or imprecise nomenclatures to describe these novel therapeutic products. The lack of uniformity and accuracy in the terminology often creates regulatory, educational, administrative, and billing quagmires. Standardization of the nomenclature for these therapeutic products is essential for creation of a harmonized regulatory and developmental framework, development of training paradigms and educational programs, equitable and rational decisions about accessibility, and consistency in the billing and coding structures used for reimbursement. Here we propose an updated framework as a foundation for categorizing these cell-based and genetically modified therapies.

Natural Killer Cell Alloreactivity Predicted By Killer Cell Immunoglobulin-Like Receptor Ligand Mismatch Does Not Impact Engraftment in Umbilical Cord Blood and Haploidentical Stem Cell Transplantation.

Natural killer cell alloreactivity is determined by killer cell immunoglobulin-like receptor (KIR) ligands in donor and recipient pairs. A small, single institution study suggested that the risk of primary graft failure after cord blood hematopoietic cell transplantation (CBT) can be predicted by host-versus-graft (HvG)-directed natural killer cell alloreactivity. In the haploidentical transplantation (Haplo HCT) cohort, graft failures were observed only in graft-versus-host (GvH) KIR ligand mismatched pairs. A subsequent study was designed to explore the association between HvG and GvH KIR ligand mismatching and engraftment in both CBT and Haplo HCT using the large, multicenter transplant population of the Center for International Blood and Transplant Research database. Nine hundred single CBT (sCBT), 954 double CBT (dCBT), and 671 Haplo HCT performed between 2008 and 2017 for acute leukemias and myelodysplastic syndrome were examined. Several models of KIR-L interactions were analyzed by multiple regression analyses for their association with engraftment, overall survival (OS), and transplant-related mortality (TRM). In sCBT, although HvG or bidirectional KIR ligand mismatch (KIR-L-MM) was initially associated with higher TRM in the first 6 months after transplantation, this effect was nullified after 6 months such that long-term survival was not different compared to GvH KIR-L-MM or KIR-L matched (KIR-L-M) pairs. There was no significant difference in neutrophil and platelet engraftment. In dCBT, no significant differences were seen in engraftment, OS and TRM. In the Haplo cohort there was faster platelet recovery in the GvH KIR-L-MM/KIR-L-M pairs versus HvG KIR-L-MM or bidirectional mismatch (HR 1.23, P= .0116). There was no significant association with OS, TRM, or neutrophil engraftment. In this large registry study, KIR-L mismatching did not significantly impact engraftment, TRM, or survival in CBT and Haplo HCT, although an association with platelet engraftment in Haplo HCT was demonstrated.

Targeted Marrow Irradiation Intensification of Reduced-Intensity Fludarabine/Busulfan Conditioning for Allogeneic Hematopoietic Stem Cell Transplantation.

Reduced-intensity conditioning (RIC) regimens frequently provide insufficient disease control in patients with high-risk hematologic malignancies undergoing allogeneic hematopoietic stem cell transplantation (HSCT). We evaluated intensification of fludarabine/busulfan (Flu/Bu) RIC with targeted marrow irradiation (TMI) in a dose escalation with expansion phase I clinical trial. TMI doses were delivered at 1.5 Gy in twice daily fractions on days -10 through -7 (dose levels: 3 Gy, 4.5 Gy, and 6 Gy), Flu (30 mg/m2 for 5 days) and Bu (area under the curve, 4800 µM*minute for 2 days). Eligible patients were age ≥18 years with high-risk hematologic malignancy and compromised organ function ineligible for myeloablative transplantation (n = 26). The median patient age was 64 years (range, 25 to 76 years). Nineteen patients (73%) had active or measurable residual disease at transplantation. One-year disease-free survival and overall survival were 55% (95% confidence interval [CI], 34% to 76%) and 65% (95% CI, 46% to 85%), respectively. Day +100 and 1 year transplantation-related mortality were 4% (95% CI, 0.6% to 27%) and 8.5% (95% CI, 2% to 32%), respectively. The 1-year cumulative incidence of relapse was 43% (95% CI, 27% to 69%). Rates of grade II-IV and III-IV acute GVHD rates were 57% (95% CI, 39% to 84%) and 22% (95% CI, 9% to 53%), respectively. Whole blood immune profiling demonstrated enrichment of central/transitional memory-like T cells with higher TMI doses, which correlated with improved survival compared with control samples from patients undergoing allogeneic HSCT. Intensification of a Flu/Bu RIC regimen with TMI is feasible with a low incidence of transplantation-related mortality in medically frail patients with advanced malignancies. The recommended phase 2 TMI dose is 6 Gy.

A Phase I Study to Determine the Maximum Tolerated Dose of ex Vivo Expanded Natural Killer Cells Derived from Unrelated, HLA-Disparate Adult Donors.

The administration of allogeneic natural killer (NK) cells following a lymphodepleting chemotherapy regimen is emerging as a well-tolerated therapeutic approach in the management of various malignancies. Contrary to the expected complications of allogeneic T cell therapy, there remains no evidence of graft-versus-host disease (GVHD) mediated by NK cells in numerous clinical trials. On the contrary, preclinical and clinical studies suggest that NK cells do not induce GVHD and in fact may prevent its development following allogeneic hematopoietic cell transplantation (HCT). In this study, we sought to determine the maximum tolerated dose of non-HLA-matched donor NK cells derived from peripheral blood and ex vivo expanded using a novel feeder cell platform. In a single-center Phase I clinical trial using a 3 × 3 design, 9 subjects each received 2 infusions of NK cells 2 weeks apart following a preparative regimen of cyclophosphamide (60 mg/kg i.v.) and fludarabine (25 mg/m2/day i.v for 5 days). No exogenous cytokines were administered. NK cells were administered at 3 dose levels: 1 × 107/kg, 2.5 × 107/kg, and 5 × 107/kg. Three subjects had myelodysplastic syndrome (MDS) or acute myelogenous leukemia (AML), and the other 6 subjects had colorectal carcinoma. Recipients were monitored over a 4-week period for GVHD as well as other adverse events and for persistence of donor NK cells in systemic circulation. Disease assessment was started at 28 days following the first NK cell infusion and continued until postinfusion day 100 or disease progression. In all 9 study subjects, there was no occurrence of GVHD and no dose-limiting toxicities that would warrant cohort expansion at any of the 3 planned cell dose levels. Low-level donor NK cell persistence was observed up to 4 weeks after the first NK cell infusion at all dose levels. The best observed response was a complete response with incomplete platelet recovery in a MDS subject who experienced disease relapse after prior allogeneic HCT. Other responses were stable disease in 1 subject with MDS and 2 subjects with colorectal cancer up to postinfusion day 100. This off-the-shelf, third-party NK cell product can be administered safely without inducing GVHD and exhibits in vivo persistence promoted by preparative lymphodepletion alone. The observed clinical responses could be enhanced by administration of exogenous cytokine support, as well as complementary approaches that promote NK cell function in the tumor microenvironment.

Multiple site place-of-care manufactured anti-CD19 CAR-T cells induce high remission rates in B-cell malignancy patients.

Chimeric antigen receptor (CAR) T cells targeting the CD19 antigen are effective in treating adults and children with B-cell malignancies. Place-of-care manufacturing may improve performance and accessibility by obviating the need to cryopreserve and transport cells to centralized facilities. Here we develop an anti-CD19 CAR (CAR19) comprised of the 4-1BB co-stimulatory and TNFRSF19 transmembrane domains, showing anti-tumor efficacy in an in vivo xenograft lymphoma model. CAR19 T cells are manufactured under current good manufacturing practices (cGMP) at two disparate clinical sites, Moscow (Russia) and Cleveland (USA). The CAR19 T-cells is used to treat patients with relapsed/refractory pediatric B-cell Acute Lymphocytic Leukemia (ALL; n = 31) or adult B-cell Lymphoma (NHL; n = 23) in two independently conducted phase I clinical trials with safety as the primary outcome (NCT03467256 and NCT03434769, respectively). Probability of measurable residual disease-negative remission was also a primary outcome in the ALL study. Secondary outcomes include complete remission (CR) rates, overall survival and median duration of response. CR rates are 89% (ALL) and 73% (NHL). After a median follow-up of 17 months, one-year survival rate of ALL complete responders is 79.2% (95%CI 64.5‒97.2%) and median duration of response is 10.2 months. For NHL complete responders one-year survival is 92.9%, and median duration of response has not been reached. Place-of-care manufacturing produces consistent CAR-T cell products at multiple sites that are effective for the treatment of patients with B-cell malignancies.

Prophylactic Tocilizumab Prior to Anti-CD19 CAR-T Cell Therapy for Non-Hodgkin Lymphoma.

Anti-CD19 chimeric antigen receptor T (CAR-T) cells have demonstrated activity against relapsed/refractory lymphomas. Cytokine release syndrome (CRS) and immune effector cell - associated neurotoxicity syndrome (ICANS) are well-known complications. Tocilizumab, a monoclonal antibody targeting the interleukin-6 (IL-6) receptor was administered 1 hour prior to infusion of anti-CD19 CAR-T cells with CD3ζ/4-1BB costimulatory signaling used to treat non-Hodgkin lymphoma patients. Relapsed/refractory lymphoma patients treated with anti-CD19 CAR-T cells were included in this analysis. Cytokine plasma levels were measured by electrochemiluminescence before lymphodepleting chemotherapy, prior to infusion and then on days 2, 4,6, and 14 days after treatment. Twenty patients were treated. Cell products included locally manufactured anti-CD19 CAR-T (n=18) and tisagenlecleucel (n=2). There were no adverse events attributed to tocilizumab. Ten patients had grade 1-2 CRS at a median of 4 (range 3-7) days. There were no cases of grade ≥3 CRS. Five patients had ICANS, grade 1 (n=4) and grade 4 (n=1). Laboratory studies obtained prior to lymphodepleting chemotherapy were comparable between patients with and without CRS, except for interleukin (IL)-15 plasma concentrations. patients with CRS had higher post-infusion ferritin and C reactive protein, with more marked increases in inflammatory cytokines, including IL-6, IL-15, IFN-γ, fractalkine and MCP-1. Fifteen patients (75%) achieved CR and 2 (10%), PR. One-year OS and PFS estimates were 83% and 73%. Prophylactic tocilizumab was associated with low CRS incidence and severity. There were no adverse events associated with tocilizumab, no increase in frequency or severity of ICANS and excellent disease control and overall survival.

Diffuse Large B Cell Lymphoma in Patients 80 Years and Older: Worse Survival After Treatment Without Increased Relapse Rates.

BACKGROUND: Age is an adverse prognostic factor in diffuse large B cell lymphoma (DLBCL), but there are limited data on the outcomes of patients' ≥80 years, including those treated with dose reduced chemoimmunotherapy. PATIENTS AND METHODS: We conducted a retrospective analysis of 542 patients, 85 (16%) were ≥80 years of age. RESULTS: Although the very elderly group had more frequent comorbidities and decreased performance status, 89% received therapy. Four-year PFS was 42% vs. 61% (P < .001) in patients ≥80 years vs. younger patients, while 4-year OS was 42% vs. 72% (P < .0001), respectively. In patients treated with anthracycline-containing regimens (n = 416) 4-year cumulative incidence of relapse with death as competing risk was not different between age groups. Median survival for DLBCL patients ≥80 years treated with R-CHOP or R-miniCHOP was 4.5 years. Survival after first relapse was significantly different between age groups: 5 vs. 19 months (P = .002), respectively. CONCLUSION: Very elderly DLBCL patients have worse OS and PFS compared with younger patients but can achieve long term disease control and potentially be cured with chemoimmunotherapy. Older DLBCL patients treated with effective regimens do not have increased rates of relapse, but outcomes after relapse remain poor.

Socioeconomic Factors and Survival of Multiple Myeloma Patients.

BACKGROUND: Outcome of Multiple Myeloma (MM) patients has improved as the result of the introduction of novel medications and use of autologous hematopoietic cell transplantation. However, this improvement comes at the expense of increased financial burden. It is largely unknown if socioeconomic factors influence MM survival. METHODS: We used the National Cancer Database, a database that houses data on 70% of cancer patients in the US, to evaluate the effect of socioeconomic factors on the survival of 117,926 MM patients diagnosed between 2005 and 2014. RESULTS: Patients aged ≥65 years who were privately insured lived longer than patients with Medicare (42 months vs. 31 months, respectively, p < 0.0001). Treatment in academic institutions led to better survival (HR: 1.49, 95% CI: 1.39, 1.59). Younger age, fewer comorbidities, treatment in academic centers, and living in a higher median income area were significantly associated with improved survival. After adjusting for confounders, survival of Medicare patients was similar to those with private insurance. However, the hazard of death remained higher for patients with Medicaid (HR: 1.59, 95% CI: 1.36, 1.87) or without insurance (HR: 1.62, 95% CI: 1.32, 1.99), compared to privately insured patients. CONCLUSION: Economic factors and treatment facility type play an important role in the survival of MM patients.

Efficacy and cost-benefit of filgrastim administered after early assessment bone marrow biopsy during induction therapy for acute myeloid leukemia.

The role of filgrastim during acute myeloid leukemia (AML) induction therapy remains controversial. At our institution, newly diagnosed AML patients from 2003 through 2019 were retrospectively evaluated. Patients were stratified on whether they received filgrastim within 5 days after early assessment bone marrow (BMBx) and divided into early GCSF group (eGCSF) and no-eGCSF group. A total of 121 patients were included. We found significantly shorter hospital stay (median 24 vs 26 days, p < .01), absolute neutrophil count recovery days (median 23 vs 25 days, p = .03), and intravenous antibiotics days (mean 18.5 vs 21.4 days, p = .01) in patients with eGCSF comparing with no-eGCSF. There was no significant difference regarding complete response rates; however, for those failed to achieve remission, eGCSF was associated with higher blast count. There was no significant difference regarding overall survival or progression-free survival. The use of eGCSF was associated with cost savings of $5199 per patient over no-eGCSF.

History of drug use in allogeneic hematopoietic cell transplant recipients.

Allogeneic hematopoietic cell transplant (HCT) is a curative therapy for malignant and non-malignant blood diseases. Drug use may be associated with adverse outcomes. We performed a retrospective analysis to assess non-relapse mortality (NRM) and overall survival (OS) in HCT patients with drug use. The medical charts of 232 patients were reviewed. Recipients of matched unrelated donor (MUD) or matched related donor (MRD) transplants were included. Drug use was defined by either metabolic evidence or provider documentation prior to transplant. Transplants were MUD (n = 148) or MRD (n = 84). Median follow-up duration was 15.5 months. There were 35 (15%) patients in the drug use group and 197 (85%) patients in the control group; 49% and 60.4% were in remission at the time of transplant, respectively. In univariate analysis, drug use was associated with a 3-year cumulative incidence of NRM of 43% vs 29% for the control group (p = 0.048), and an HR of 1.75, (95% CI: 1.02-2.99). After controlling for age, sex, disease status, and graft type, drug use was associated with a hazard ratio (HR) of 1.6 (95% CI: 0.95-2.92) for NRM, and an HR 1.2 (95% CI: 0.74-1.94) for OS. Larger cohorts may be needed to further evaluate this association.

Cryopreservation of hematopoietic cells using a pre-constituted, protein-free cryopreservative solution with 5% dimethyl sulfoxide.

BACKGROUND AIMS: Adequate cryopreservation techniques are critical to ensure optimal recovery of functional progenitor cells in hematopoietic cell (HC) transplantation, minimize risk of contamination and prevent infusion-related adverse events (irAEs). In this article, we provide graft function and infusion safety results observed by decreasing the concentration of dimethyl sulfoxide (DMSO) in cryopreservative media and by minimizing processor-dependent formulation. METHODS: Ten HC products, collected after standard mobilization of multiple myeloma patients, were cryopreserved with PRIME-XV FreezIS (FreezIS) and compared with products previously cryopreserved with media formulated in-house to achieve a final DMSO concentration of 10% (Std10) and 5% (Std5). At infusion, HCs were analyzed for recovery of CD34+ cells and viability; irAEs and time to engraftment of neutrophils and platelets were also monitored. RESULTS: Median CD34+ cell recovery for HC cryopreserved with Std10, Std5 and FreezIS was 38%, 78% and 68%, respectively (P = 0.0002). There were less frequent irAEs with Std5 and FreezIS (10%) compared with Std10 (80%) (P ≤ 0.0001). Median time to neutrophil engraftment was comparable (11 days) for all three groups, while platelet engraftment occurred at a median of 20, 19 and 17 days, respectively (p-values not significant). CONCLUSIONS: FreezIS, a Good Manufacturing Practice-grade, pre-constituted cryopreservative with low DMSO content, maintains functional viability of the HC product while reducing the incidence of irAEs compared with 10% DMSO solutions. The pre-constituted nature of this agent also decreases processor-dependent handling, hence decreasing the risk of variability and infection.

Interrogating the impact of KIR ligand mismatch in engraftment following HLA-disparate stem cell transplantation.

The effects of donor-derived natural killer (NK) cell alloreactivity on disease relapse and transplant-related mortality following allogeneic stem cell transplantation have been described while the impact of recipient-derived NK cell alloreactivity on donor engraftment is not well known. Epitopes of HLA Class I molecules act as ligands for NK cell killer immunoglobulin-like receptors (KIR) regulating their cytotoxicity. As such, NK cell alloreactivity is predictable from KIR ligand mismatches between donors and recipients. We analyzed the impact of KIR ligand mismatch (KIR-L-MM) on donor engraftment in 70 cord blood transplants (CBT) and 26 haploidentical transplants (HaploSCT). In CBT, host-versus-graft-directed KIR-L-MM predicted primary graft failure; an effect not mitigated by use of ATG. This trend was most significant with HLA-C KIR-L-MM. In addition, graft-versus-host-directed KIR-L-MM predicted the dominant cord blood unit in double CBT. In the limited HaploSCT cohort, host-versus-graft-directed KIR-L-MM did not predict graft failure. Time to neutrophil engraftment was unaffected by KIR-L-MM in either CBT or HaploSCT. The direction of KIR-L mismatch may be a parameter to consider when selecting CBT units to ensure successful engraftment. The role of KIR-L-MM in CBT and HaploSCT engraftment merits further exploration in a large transplant database.

Inhibition of 15-PGDH Protects Mice from Immune-Mediated Bone Marrow Failure.

Aplastic anemia (AA) is a human immune-mediated bone marrow failure syndrome that is treated by stem cell transplantation for patients who have a matched related donor and by immunosuppressive therapy (IST) for those who do not. Responses to IST are variable, with patients still at risk for prolonged neutropenia, transfusion dependence, immune suppression, and severe opportunistic infections. Therefore, additional therapies are needed to accelerate hematologic recovery in patients receiving front-line IST. We have shown that inhibiting 15-hydroxyprostaglandin dehydrogenase (15-PGDH) with the small molecule SW033291 (PGDHi) increases bone marrow (BM) prostaglandin E2 levels, expands hematopoietic stem cell (HSC) numbers, and accelerates hematologic reconstitution following murine BM transplantation. We now report that in a murine model of immune-mediated BM failure, PGDHi therapy mitigated cytopenias, increased BM HSC and progenitor cell numbers, and significantly extended survival compared with vehicle-treated mice. PGDHi protection was not immune-mediated, as serum IFN-γ levels and BM CD8+ T lymphocyte frequencies were not impacted. Moreover, dual administration of PGDHi plus low-dose IST enhanced total white blood cell, neutrophil, and platelet recovery, achieving responses similar to those seen with maximal-dose IST with lower toxicity. Taken together, these data demonstrate that PGDHi can complement IST to accelerate hematologic recovery and reduce morbidity in severe AA.

Aggressive lymphoma subtype is a risk factor for venous thrombosis. Development of lymphoma - specific venous thrombosis prediction models.

Venous thromboembolic events (VTE) are a frequent complication of lymphoma. We conducted a retrospective analysis to compare VTE risk in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). Subjects were randomly assigned to training and validation sets to identify risk factors of VTE and evaluate risk model performance, including the Khorana score. A group of 790 patients were diagnosed from 2002 to 2014 (DLBCL = 542, FL = 248). Median follow- up was 49 months. We observed 106 VTE, with higher incidence in DLBCL (5-year cumulative incidence = 16.3% vs 3.8% in FL patients). Five-year OS for patients with VTE was 51.4% vs 73.1% in patients without VTE (P < .001). Baseline VTE risk factors identified in the training cohort included lymphoma subtype, previous VTE, ECOG performance status ≥2, decreased albumin, increased calcium, elevated WBC, absolute lymphocyte count or monocyte count, and presence of bulky disease. Addition of new variables to the Khorana score improved its performance measured by Akaike information criterion and Concordance index. A new risk model including lymphoma subtype, albumin, WBC count, and bulky disease was validated in time-based ROC analyses. These findings were confirmed in the validation cohort. Lymphoma subtypes have different VTE risk. The effect of lymphoma subtype was independent from disease burden and the use of systemic therapy. The Khorana risk-score was validated in time to event analyses, and a more robust lymphoma-specific VTE risk score is proposed. These findings suggest lymphoma patients with highest VTE risk can be identified with baseline parameters.