Zubair, Abba C.

Blood plasma is a readily accessible source of extracellular vesicles (EVs), i.e., cell-secreted nanosized carriers that contain various biomolecules, including glycans. Previous studies have demonstrated that glycans play a major role in physiological and pathological processes, and certain plasma glycans have been associated with disease conditions. However, glycome studies have been limited by a lack of analytical techniques with the throughput capacity necessary to study hundreds of clinical samples. This study is the first to characterize the EV plasma glycome based on all major glycan classes. The results based on glycan node analysis revealed, as expected, that plasma-derived EVs have distinct glycan features from donor-matched whole plasma. Specifically, glycan nodes corresponding to those observed in chondroitin sulfate, dermatan sulfate, type I keratan sulfate, and type II keratan sulfate were enriched on EVs. The identification of specific differences in glycan features in plasma vs. plasma-derived EVs is relevant for understanding the physiological role of EVs and as a reference for future diagnostic studies. Additionally, the results indicate that EV glycan nodes do not substantially differ among a small set of healthy donors. These results lay the framework for the further evaluation of all EV glycan classes as diagnostic markers, therapeutic targets, and biologically active components in health and disease.

AbstractSevere cases of COVID-19 infection, often leading to death, have been associated with variants of acute respiratory distress syndrome (ARDS). Cell therapy with mesenchymal stromal cells (MSCs) is a potential treatment for COVID-19 ARDS based on preclinical and clinical studies supporting the concept that MSCs modulate the inflammatory and remodeling processes and restore alveolo-capillary barriers. The authors performed a systematic literature review and random-effects meta-analysis to determine the potential value of MSC therapy for treating COVID-19-infected patients with ARDS. Publications in all languages from 1990 to March 31, 2020 were reviewed, yielding 2691 studies, of which nine were included. MSCs were intravenously or intratracheally administered in 117 participants, who were followed for 14 days to 5 years. All MSCs were allogeneic from bone marrow, umbilical cord, menstrual blood, adipose tissue, or unreported sources. Combined mortality showed a favorable trend but did not reach statistical significance. No related serious adverse events were reported and mild adverse events resolved spontaneously. A trend was found of improved radiographic findings, pulmonary function (lung compliance, tidal volumes, PaO2/FiO2 ratio, alveolo-capillary injury), and inflammatory biomarker levels. No comparisons were made between MSCs of different sources.Significance statement The potential benefits of mesenchymal stromal cell (MSC) therapy for patients with COVID-19 acute respiratory distress syndrome support the rapid commencement of clinical trials, as well as the compassionate use of MSCs that already have documented safety profiles from FDA-approved studies.

Abstract Background: Previous studies have proposed combination of various factors that predict poor mobilization after GCSF stimulation. However, there is no single clinical or laboratory test that reliably correlates with bone marrow reserve and PBPC mobilization. Peripheral blood CD34+ cell count (pCD34) reliably correlates with PBPC mobilization and yield but only after GCSF administration. Methods: We have prospectively followed 36 autologous PBPC transplant candidates, from the time of initial evaluation to transplant, to evaluate factors the correlate with bone marrow reserve and autologous PBPC mobilization. Results: The patients median age was 63 (range 26 – 76). 21 of the 36 patients were diagnosed with dysproteinemia, primarily multiple myeloma, 10 patients had non-Hodgkin’s lymphoma while the remaining 5 had other form of hematological malignancies. Our evaluation shows baseline platelet count prior to growth factor administration significantly correlate with total CD34+ cell yield (spearman: r = 0.64, p <0.001, Figure 1). In addition, daily platelet count during PBPC harvest correlate with CD34+ cell yield for the day (spearman: r = 0.6, p <0.001). Using multiple linear regression model (F = 19.1, p <0.001, R2 = 0.64), we have determined patients’ age (p = 0.03) and type of disease (p <0.001), in addition to platelet count (p<0.001), significantly correlate with total CD34+ cell yield. Further analysis showed low baseline platelet count predicts poor PBPC mobilization. Using Receiver Operating Curve (ROC), we have determined that platelet count of 174,000/ul was the best cut-off for collecting at least 2 million/Kg CD34+ cells with sensitivity of 81% and specificity of 78% and estimated correct classification of 81%. Even though pCD34 counts were slightly more sensitive and were better at identifying poor mobilizers in our cohort (best cut-off 10/ul, sensitivity 96%, specificity 67%, correct classification 89%), their clinical utility were diminished since the values were only known after GCSF administration. Conclusion: Baseline platelet count is a sensitive predictor of bone marrow reserve and can be used prior to growth factor administration to predict poor mobilization. Figure 1: Correlation of baseline platelet count and total CD34+ cell yield Figure 1:. Correlation of baseline platelet count and total CD34+ cell yield

Abstract Most common abnormalities in MDS involve the loss of chromosomal material resulting from the loss of an entire chromosome or a part of it, due to deletions or unbalanced translocations. Among partial chromosome losses, del (5q) was found to be the most common followed by del (20q). MDS can also be associated with multiple morphologic RBC abnormalities including macrocytes, ovalocytes, dacrocytes, fragmented cells and basophilic stippling. Limited cases of MDS with elliptocytosis have been reported in the literature. Elliptocytosis encompasses a heterogeneous group of erythrocyte disorders. Although acquired cases of elliptocytosis have been reported, these are most often hereditary disorders with a variable clinical presentation from asymptomatic carriers to patients with severe hemolytic anemia. This disorder is quite rare in the Unites States (US). Mutations in protein 4.1, alpha spectrin, beta spectrin, glycophorin C and band 3 have been reported in hereditary elliptocytosis. Only 7 well reported cases of marked elliptocytosis associated with MDS have been reported in the literature. Of those 7 cases, 4 of them were associated to del(20q). All of them were elderly males and all of them had ≤ 5% bone marrow blasts. Anemia is usually moderate (median 9.4 g/dL; range 8.1–12) and thrombocytopenia is mild to moderate (median platelet count 116 x 109/L; range 46–149 x 109/L). All cases were described either in Europe (n= 1; Rummens et al. Acta Haematologica1986; 75:174–177) or in Asia (n= 3; Ideguchi et al. Br J Haematol.1993, 75:387–92; Ishida et al. Cancer Genetics and Cytogenetics1997, 108:162–165; Hur et al. Clin Lab Haematology, 2004, 26: 69–72). Of these 7 cases, 3 of them were associated with protein 4.1 deficiency. To the best of our knowledge these are the first 2 cases of patients with marked elliptocytosis and MDS with del 20q abnormality reported in the US: Patient 1 Patient 2 Age/sex 82/male 79/male FAB classification RA RA Year of diagnosis of MDS 1998 1999 WBC 3.0 x 109/L 11.5 x 109/L Platelets 82 x 109/L 79 x 109/L Hemoglobin 11.8 g/dL 10.7 g/dL Hematocrit 34.4% 31.9% Reticulocyte 4.3% NA LDH 350 u/L NA Direct Coombs Negative NA BM Cytogenetics 46 XY, del (20)(q11.2) 46 XY, del (20)(q11.2) Prior Therapy supportive care only Erythropoeitin Evaluation for protein 4.1 deficiency in one of these 2 patients is currently pending. The elliptocytosis noted in these MDS patients were most likely derived from acquired clones with abnormal development of the erythroid lineage and were associated with deletion of chromosome 20q. Patients with acquired elliptocytosis and associated MDS with del 20q chromosomal abnormality seem to have an indolent course with prolonged history of mild to moderate blood cytopenias and low risk to transformation to acute leukemia. Further research is needed to deduce the clinical significance of this subtype of MDS with this unusual RBC morphology

Abstract Transfusion of ABO-mismatched platelets is common practice. Although a unit of single donor apheresis platelet (SDP) contains as much plasma and passive anti-A or/and anti-B antibodies (allo-agglutinins) as a unit of fresh frozen plasma, ABO- mismatched platelet transfusions are considered safe and hemolytic transfusion reactions have only rarely been reported. We report a case of a 67-year old male, blood group A, with mantle cell lymphoma who received 1 SDP for chemotherapy induced thrombocytopenia. Several prior platelet transfusions had been uneventful. After 150 ml of irradiated, leukoreduced, SDP from blood group O donor had been infused, he developed nausea, light-headiness, chills, and back pain. He became bradycardic and hypotensive. Platelet transfusion was discontinued and intravenous dexamethasone and rapid saline infusion was administered. Later, his hemoglobin dropped from 10.6 to 7.4 g/dl and total serum bilirubin increased by 9 fold. A direct antiglobulin test (DAT) on post-transfusion sample demonstrated 1+ reactivity at room temperature. An elution test performed on the patient’s circulating red blood cells contained anti-A antibodies. These results are consistent with a severe acute hemolytic transfusion reaction. The donor anti-A and anti-B antibodies titers at room temperature and at 37°C were 512 and 2048 with A1 cells and 128 and 256 with B cells, respectively.This case illustrates the rare possibility of hemolytic transfusion reaction occurring as a result of ABO-mismatched platelets from group O donor with high-titer anti-A antibodies. SDP (in contrast to pooled platelets) offers the advantages of reduced risk of infection transmission and alloimmunization by limiting exposure to one donor only. However, it increases the opportunity for hemolytic transfusion reaction to occur if the donor has high-titer antibodies which would have been diluted if pooled platelets were used. As SDP use becomes more widespread, the risk of clinically significant hemolytic reactions is likely to increase, especially in seriously ill patients who tolerate these reactions particularly poorly. Moreover, increasingly, apheresis platelets are being donated by a small group of highly motivated donors, raising the chances of repeated transfusions from the same donors. We propose that the safety of ABO-mismatched platelet transfusions be re-evaluated. Effectiveness (and costs) of potential preventive strategies such as screening all SDP units for high-titer antibodies and/or plasma volume reduction of all mismatched SDP units should be studied.

Abstract Background: IgM multiple myeloma (MM) are very rare plasmaproliferative disorders representing 0.5–1.2% of all cases of MM and < 0.2% of all IgM monoclonal gammopathies. Clinical criterion are not always helpful in differentiating IgM MM from Waldenstrom macroglobulinemia. However, the presence of lytic bone lesions, absence of lymphadenopathy and/or hepatosplenomegaly, presence of translocation of the immunoglobulin heavy chain locus at 14q32 [t(11;14), t(14;16), t(4;14)], and strong expression of CD138 by the plasma cells are useful in the diagnosis of IgM MM. It has been our experience and of others that these cases have an aggressive behavior at presentation, shorter survival than IgG and IgA MM and poor response to therapy for lymphoplasmacytoid lymphomas. We present here 2 cases of IgM MM with a dramatic response to Lenalidomide and low dose dexamethasone (Rev/Dex) Results: Baseline patient characteristics at time of diagnosis of IgM MM and therapy outcome are presented in the following 2 tables: Table 1. Case 1 2 Age and sex 72 (F) 73 (F) Serum M-spike (g/dL) 5.3 6.2 Urine M-spike (mg/dl/24 hrs) 72 412 Serum IgM (mg/dL) 8,590 11,000 BM plasma cells percentage 90 20 Plasma cell immunophenotyping CD138+++, partial CD20, CD56− CD138+++, partial CD20, CD56− Cytogenetics (Standard and/or FISH) Standard: normal FISH: not done on initial biopsy. On follow up there were insufficient number of plasma cells to perform test Standard: of 20 metaphases, 6 had a complex hypotetraploid karyotype with relative loss of 13q, 14, 15, 16, 20, and 22, and numerous unbalanced rearrangements. FISH: a plasma cell clone with monosomy 13 and IGH/c-MAF fusion, t(14;16). In addition, approximately 60% of plasma cells had a tetraploid clone with the same anomalies as well as relative loss of p53 Bone lesions Multiple non-traumatic spinal fractures and of stenum Several lytic lesions of long bones Renal insufficiency No No Anemia (Hbg g/dL) Yes (8.7) Yes (8.1) Hypercalcemia (Ca mg/dL) Yes (12.5) Yes (11.4) Beta 2 microglobulin (mg/dL) 5.79 8.51 Serum viscosity (cpoise) 5.9 4.8 Table 2. Best Response to therapy Case Therapy Best Response Comments 1 Rituxan, then Fludarabine based therapy Transient response Rapid progression after partial and transient response to each therapy 1 Lenalidomide + LD-Dex sCR after cycle #6. Currently on CR 18 months later IgM declined from 8,590 to 43 mg/dL after 4 cycles of Rev/Dex. 2 Lenalidomide + LD-Dex VGPR after cycle #2 IgM declined from 11,000 to 463 mg/dL after cycle 3. Complete disappearance of M-spike in serum; BM to be done after cycle #4 Conclusions: This is the first report that we are aware of a rapid and dramatic response to lenalidomide and low dose dexamethasone in these rare cases of IgM MM with poor response to NHL-type treatment. Lenalidomide-based therapy might abrogate poor prognosis cytogenetics in this unusual subtype of MM (case #2), however, follow up for this patient is still very short.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment of relapsed/refractory B-cell lymphoid malignancies. Axicabtagene ciloleucel (axi-cel), an anti-CD19 CAR-T not only targets the malignant B-cell, but can potentially also target and eliminate normal B-cells. This can interfere with the normal B-cell repertoire, compromising host humoral immunity such as decreased titers of common vaccines (DTaP, MMR). To assess if this was a clinically significant problem, we evaluated all recipients of axi-cel at our center between 6/2018 through 7/2019. Patients and methods: For patients who received commercial axi-cel, humoral immunity was evaluated both quantitatively [absolute lymphocyte count (ALC)] as well as qualitatively by serology titers [IgG antibodies (Abs)] for diphtheria, tetanus, pertussis, measles, mumps, and rubella, and total Immunoglobulin G (IgG) levels. Data was collected within 30 days prior to CAR-T infusion, then at day +30 and between days +60 and +100 after CAR-T infusion. Results: We identified 10 patients (males = 5, 50%), with a median age of 49.9 years (range 30-65) who received commercial axi-cel during the study period. Patient characteristics and indications for CAR-T therapy are shown in Table 1; the cohort represented a heavily pre-treated aggressive B-cell lymphoma patient population. Baseline information on antibody (Ab) titers was available in 8 patients. At baseline, all patients had positive tetanus IgG Abs (≥0.01 IU/mL), 7 had positive diphtheria IgG Abs (≥0.01 IU/mL), 6 had positive measles IgG Abs (≥ 1.1 AI), 5 had positive rubella IgG Abs (≥ 1.0 AI), 3 had positive mumps IgG Abs (≥ 1.1 AI). None of the patients had a positive pertussis IgG Abs (≥100 IU/mL). At follow-up, all patients with positive Ab at baseline maintained titers in the positive range at day +30 and between days +60 and +100 (Figure 1). None of the patients demonstrated a clinically meaningful decrease in Abs titers, despite a drop in ALC and IgG levels (table 2). Conclusions: Albeit a small sample size, IgG Ab titers for diphtheria, tetanus, measles, mumps, and rubella did not appear to be affected by axi-cel at a short interval follow-up after infusion (up to day +100). We plan to extend this analysis in a larger cohort with a longer-term prospective follow-up to validate our findings, especially in light of dropping absolute lymphocyte counts and IgG levels. Disclosures Ailawadhi: Celgene: Consultancy; Amgen: Consultancy, Research Funding; Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy; Pharmacyclics: Research Funding. Foran:Agios: Honoraria, Research Funding. Tun:Celgene: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Mundi-pharma: Research Funding; DTRM Biopharma: Research Funding; BMS: Research Funding. Chanan-Khan:Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; AbbVie: Research Funding; Xencor: Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy.

Abstract Background Umbilical cord blood (UCB) is an important alternative source of stem cells for patients who lack matched adult donors, particularly in ethnic minorities. The infused total nucleated cell (TNC) and CD34+ cell dose are important prognostic factors on transplant outcomes. UCB units collected from African Americans (AA) have lower TNC and CD34+ cell counts and more likely to be disqualified for banking compared to other racial and ethnic groups. Furthermore, AA, including pregnant women, have increased prevalence of vitamin D deficiency. Vitamin D has an established role in hematopoiesis; therefore, we investigated the racial differences in UCB vitamin D content and its correlation with UCB cell composition and hematopoietic potential. Methods 119 UCB units that did not meet the TNC count banking criteria were analyzed. 51 UCB units were collected from AA mothers and 68 from Caucasian mothers. We analyzed UCB variables including volume, hematocrit (HCT), TNCs, mononucleated cells (MNC), CD34+ cells, plasma 25-Hydroxy vitamin D [25(OH)D] and in vitro progenitor cell hematopoietic potential measured by Colony-Forming Cell (CFC) assay. Results The median values of 25(OH)D in UCB units were significantly lower in AA compare to Caucasians (p= <.0001). Severe vitamin D deficiency < 10 ng/mL was exclusively detected in UCB units from AA (19/51; 37%) and plasma 25(OH)D concentration < 20 ng/mL was more prevalent in AA (43/51 units; 84%), compare to Caucasians (15/68 units; 22%). UCB units from AA had lower absolute numbers of TNC (p= .0016), MNC (p= .0261), and CD34+ cells (p= .0257) compare to Caucasians. No difference in median CFC/10,000 MNC was detected between AA and Caucasians (p= 0.661) (Table 1). Univariate analysis of 25(OH)D effect on UCB variables revealed a correlation between 25(OH)D level and TNC (r= 0.193, 95% CI 0.013-0.36; p= .0353) and UCB HCT (r= 0.196, 95% CI 0.016-0.363; p= .0327). A significantly higher MNC count was noted when 25(OH)D concentration was ≥ 20ng/mL (4.5x 108, range (1.7-9.5) vs. 3.9x 108, range (0.8-9); p= .0329). This correlation between 25(OH)D level and TNC and MNC was not detected after adjustment for race (Figure 1). However, 25(OH)D concentration ≥ 20 ng/mL significantly correlated with CBU HCT in AA race (median 31.9% (24-42) vs. 27.8%, range (21.4 - 40); p= .0124). Conclusion 25(OH)D level, TNC and HCT are all significantly lower in UCB units from AA compare to Caucasians. Independent of race, 25(OH)D directly correlated with TNC and MNC. These data suggest vitamin D and other yet to be determined factors play an important role in the mechanism of low UCB cell and progenitor counts. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 349 Failure to collect enough CD34+ cells following poor hematopoietic progenitor cell (HPC) mobilization is generally thought to be due to marrow damage following previous therapies. However, marrow damage alone cannot account for all poor mobilizations since there are donors who have good marrow cellularity but fail to adequately mobilize. In addition, the relationship between CD34+ cell dose and engraftment rate is not linear, suggesting other factors play a role during engraftment. Previous animal studies suggest CD8+ T cells are important for CD34+ cell homing to the marrow. We hypothesized that CD8+ T cells have dual roles by inhibiting CD34+ cell mobilization and facilitating engraftment. To test our hypothesis, we followed 192 autologous HPC donors to assess the role of CD8+ T cells in HPC mobilization and engraftment. The median donor age was 58.5 years (range 18 – 76), and 110 of the 192 patients were males. Donors were diagnosed with plasma cell disease, primarily multiple myeloma, or non-Hodgkin's lymphoma. CD34+ and CD8+ T cell content in the patients' apheresis products were enumerated using flow cytometry, quantitative RT-PCR (qPCR) and immunohistochemistry. The median CD34+ cell/kg was 4.7 × 106. Patients were categorized as low, moderate or high mobilizers according to their total CD34+ cell collection quartile distribution: <3.7, 3.8 – 5.5 and ≥5.6 × 106/Kg respectively. We found that HPC products from low mobilizers contained significantly more CD8+ T cells (median 1.25 × 108/Kg) than HPC products from moderate and high mobilizers (Table 1 p = 0.04). Therefore, the ratio of CD8+ T cells to CD34+ cells was 4 – 8 folds higher in low mobilizers than in moderate and high mobilizers. Moreover, CD8 antigen expression measured using qPCR, normalized with 18s ribosomal RNA, was significantly higher in low mobilizers than in moderate or high mobilizers. Similar analysis with CD4+ T cells did not demonstrate significant correlation with mobilization. To assess the role of CD8+ T cells in HPC mobilization, we purified CD8+ T and CD34+ cells from both low and moderate or high mobilizers. Using chemotaxis assay, we assessed the effect of CD8+ T cells on CD34+ cell migration away from high stromal cell derived factor (SDF1-a) concentrations. Purified CD34+ cells were plated in bone marrow epithelial cell coated trans-wells and co-cultured with purified CD8+ T cells at 1:2 and 1:5 ratios in the presence of SDF-1a at 0, 200 and 400ng/ml concentrations. Cells that migrated through the micro-pores of the trans-well into the lower wells were enumerated and analyzed. Our studies showed CD8+ T cells inhibit migration of CD34+ cells in-vitro independent of SDF1-a concentration. (Figure 1) The inhibitory properties of CD8+ T cells were more pronounced on CD34+ cells from low mobilizers than on CD34+ cells from moderate or high mobilizers. We also assessed if CD8+ cell content was associated with days to neutrophil engraftment. Our analysis showed the higher the CD8+ T cell content per unit CD34+ cell, the faster the rate of neutrophil engraftment. In summary, HPC products from low mobilizers contained significantly higher numbers of CD8+ T cells. CD8+ T cells, independent of SDF1-a concentration, significantly inhibited migration of purified CD34+ cells. In addition, CD8+ T cell content per unit CD34+ cell was inversely proportional to the time to neutrophil engraftment. These findings suggest CD8+ T cells may play dual roles by inhibiting CD34+ cell mobilization and facilitating its homing and engraftment. Table 1 Association of CD8+ T cell number with CD34+ cell mobilization capacity Mobilization Quartiles Low Moderate High p-value Median CD34+ Cell × 106/Kg 3.03 4.55 6.73 <0.001 Median CD8+ T cell × 108/Kg 1.25 0.50 0.33 0.04 CD8+ T: CD34+ cell ratio 41 11 5 Figure 1 Figure 1. Disclosures: No relevant conflicts of interest to declare.