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Background: Despite effective front-line therapies, DLBCL & MM have high relapse rates. Novel therapies like CAR-T & bispecific antibodies (BsAb) offer deep & durable remission compared to salvage therapies, but have a unique toxicity profile (TP) that requires monitoring. With no head-to-head trials, the rationale for therapy selection may vary. This study explores provider choices, sequencing preferences, & access barriers. Methods: Two anonymous surveys (MM and DLBCL) of US-based Hematologists were conducted from 2/2024 to 6/2024, on practice settings, CAR-T & BsAb availability, treatment preferences & barriers. Responses were analyzed to assess preferences across clinical scenarios. Results: Surveys were completed by 37 MM & 45 DLBCL providers. Most were at centers offering both CAR-T & BsAb. Most gave CAR-T inpatient, & BsAb outpatient. CAR-T was given by 73% MM providers & 66% DLBCL (92% used Cilta-cel, 96% used Ide-cel; 100% used Axi-cel, 90% used Liso-cel & 73% Tisa-cel). In MM, 78% used Teclistamab, 60% Talquetamab & 24% Elranatamab. In DLBCL, 62% used Epcoritamab & 40% Glofitamab. Providers preferred CAR-T over BsAb in MM after 4+ prior lines of therapy (LOT) (89%), & in DLBCL after 2+ prior LOT (93%). CAR-T was favored more among academic providers & those at CAR-T centers. Practice volume did not impact selection. Among providers at centers with BsAb-only, CAR-T was preferred by 60% (MM) and 50% (DLBCL). Providers at centers without both favored CAR-T (MM: 75%, DLBCL: 86%). CAR-T was chosen for better outcomes, short treatment, center choice, & prior experience. Other factors that influenced decisions were lower incidence of cytopenia/infection & “BsAb effective post-CAR-T, less so vice versa” (MM), & “curative potential of CAR-T” (DLBCL). Logistical barriers & institutional constraints influenced BsAb selection: CAR-T unavailability, access to specialized centers, referral complexity, insurance delay, manufacturing delay & hospitalization needs. In MM, 78% providers preferred Cilta-cel over Ide-cel, especially academic providers & those with CAR-T experience. CAR-T volume did not impact selection. Cilta-cel was preferred due to perceived better response rate (RR), more experience, “progression-free survival (PFS) benefit”, center choice, & logistical issues with Ide-cel. Ide-cel was selected due to center choice, favorable TP & insurance preference. Teclistamab was preferred by 78% due to more experience, better RR, TP & center choice, Elranatamab by 11% (better TP, RR, & “PFS”), & Talquetamab by 11% due to having a non-BCMA target. Academic providers preferred Teclistamab (89% vs 50%), & nonacademic providers preferred Talquetamab (38% vs 4%) and Elranatamab (13% vs 8%). In DLBCL after 2+ LOT, 69% favored Axi-cel due to prior experience, RR, center choice, & logistical issues with other products. Liso-cel & Tisa-cel were chosen by 27% & 2%, respectively, due to favorable TP. Axi-cel was also preferred 2nd line by 73% for similar reasons, while 24% favored Liso-cel for its favorable TP. Epcoritamab was preferred by 56% (subcutaneous injection, more experience & center choice) & Glofitamab by 42% (shorter treatment duration, easy administration, more experience, & center choice). Practice setting & volume did not impact selection between products in DLBCL. InBCMA-naïve MM pts, majority (97%) chose an anti-BCMA agent over GPRC5D due to better RR, TP, prior experience, & center choice. InBCMA-exposed pts, most (92%) favored an anti-GPRC5D agent. In contrast in DLBCL, 80% chose CD19 CAR-T after prior CD19-directed therapy, & 18% chose CD20 BsAb. Therefore, antigen escape was less of a concern in DLBCL vs MM. For relapse after 2nd line CAR-T in DLBCL, 78% preferred BsAb over other salvage options due to better RR, TP, & more experience. Providers prioritized RR, survival, & TP in decision making. Treatment logistics, duration, frequency, & cost were less crucial. MM providers also prioritized quality of life, which was less so in DLBCL. There were no differences in priority based on practice setting & experience with CAR-T. Conclusion: The study highlights factors influencing therapy choices in MM & DLBCL. Despite CAR-T's potential for better outcomes, significant access barriers exist. Efforts to streamline referral pathways, logistics, & expanding availability are crucial to improve outcomes. Understanding these preferences & barriers can guide future management strategies.

Introduction: Over 80,000 new cases of Non-Hodgkin's Lymphoma (NHL) are diagnosed annually, but modifiable risk factors are largely unknown. Circadian disruption has been identified as a risk factor for several cancers, including breast and prostate cancer, and affects immune cells such as Natural Killer (NK) cells and T-helper cells. Disruptions in circadian rhythms can lead to aberrant immune cell trafficking and proliferation. Despite this biological connection, evidence linking circadian disruptions to NHL remains inconclusive. Only single Mendelian Randomization (MR) study (PMID: 32895918) has explored the causal relationship between sleep traits and overall NHL risk, without examining NHL subtypes. Studies have shown distinct risk factor profiles among NHL subtypes. Therefore, this study aims to investigate the causal relationship between sleep traits and NHL subtypes in European populations using MR. Methods: We conducted a two-sample MR analyses using genome-wide association studies (GWAS) summary data on sleep traits and NHL subtypes. The GWAS summary statistics on sleep traits were obtained from publicly available UKBiobank datasets. The sleep traits analyzed included chronotype (N=449,734), insomnia (N=237,627), sleep duration (N=446,118), daytime sleepiness (N=452,071), short sleep (N=411,934), and long sleep (N=339,926). Only independent, genome-wide significant SNPs (p < 5×10-8) were considered as valid instruments. The NHL subtype-specific summary statistics came from the InterLymph including follicular lymphoma (FL: N=6,508 cases / 64,183 controls), mantle cell lymphoma (MCL: N=1,169 cases / 61,603 controls), and Waldenström macroglobulinemia/lymphoplasmacytic lymphoma (WM/LPL: N=1,697 cases / 59,333 controls). Our primary analysis used the random-effects inverse-variance weighted (IVW) method. In addition, we employed MR-Egger to adjust for directional pleiotropy. Heterogeneity in the MR results was evaluated with Cochran's Q statistic. Results: The IVW method did not identify any statistically significant causal association between sleep traits and the risk of NHL subtypes (FL,MCL,WM/LPL), but did yield several intriguing associations. Chronotype (early rising) showed a tendency towards a marginally an increased NHL risk across subtypes [Odds ratio (OR) range: 1.07 - 2.56]. Conversely, a decreased risk was noted for long sleep (≥ 9 hours vs. 7-8 hours) [OR range: 0.19 - 0.62], insomnia [OR range: 0.72 - 0.88], and short sleep (excludes MCL) [OR range: 0.12 - 0.72]. Confidence limit for long sleep was wide due to small number of variants (N=8). The MR-Egger regression analysis did not provide evidence of significant directional horizontal pleiotropy. The F-statistics for all sleep traits were greater than 10 indicating absences of weak instrument bias. Conclusions: Our study found no statistically significant associations between sleep traits and three NHL subtypes (FL, MCL, WM/LPL) in European populations. However, we observed potential influences of chronotype, long and short sleep, and insomnia on NHL risk. These findings align with and extend previous MR study by providing subtype-specific insights. Future directions include expanding our analysis to additional NHL subtypes, generating polygenic risk scores, and conducting stratified analyses using the InterLymph population. These efforts aim to further elucidate the complex relationship between sleep characteristics and NHL risk across diverse subtypes and populations.

Introduction Multiple myeloma (MM) is considered incurable. Despite improved outcomes with novel agents, including BCMA-targeted chimeric antigen receptor (CAR) T-cell therapies, antibody-drug conjugates (ADCs), and bispecific antibodies, patients with relapsed/refractory MM (RRMM) often have poor prognoses. LINKER-MM1 (NCT03761108) is a global, single-arm, Phase 1/2 study of linvoseltamab, a BCMA×CD3 bispecific antibody, in patients with RRMM who were either triple-class exposed (TCE; previously treated with a proteasome inhibitor, immunomodulatory drug, and anti-CD38 antibody) during ≥3 prior lines of therapy (LOTs), or triple-class refractory to these therapies. Here, we present comparisons of clinical outcomes from LINKER-MM1 with those of a current, international, real-world (RW) external control arm (ECA; NCT05673967). Methods The ECA was derived from 16 academic sites of the International Myeloma Foundation International Myeloma Working Group (IMWG) (N=203; 309 eligible LOTs) and compared with linvoseltamab (N=105; Phase 2 200 mg cohort). Patients in the ECA initiated ≥1 anti-MM therapy after meeting key LINKER-MM1 eligibility criteria. Weighted random sampling and inverse probability of treatment weighting were used to select 1 LOT per patient and balance the ECA and trial populations on prespecified prognostic factors (Kumar S, et al. IMS 2023). The primary endpoint was objective response rate (ORR; IMWG criteria) determined by an independent central review committee (ICRC) based on myeloma laboratories. An independent data review committee reviewed comparability of cohorts and endpoint assessments prior to conducting comparative analyses. Results Median follow-up was 14.3 months for the linvoseltamab cohort (data cutoff: Jan 6, 2024) and 13.4 months for the ECA. After weighting, 15 prognostic factors were balanced between cohorts. Patients in the ECA received 68 distinct regimens, most commonly CAR T-cell therapies (11.3%) and ADCs (10.3%). After balancing the cohorts, patients in the ECA evaluable for response had ICRC-assessed ORR of 46.3% (40.8% by treating physician assessment), among whom 24.0% had very good partial response or better (≥VGPR). When including patients who died without evaluable response, ECA ICRC-assessed ORR was 44.2%. Linvoseltamab induced significantly higher ICRC-assessed ORR (69.5% vs 46.3%, odds ratio [OR] 2.65 [95% confidence interval (CI) 1.66-3.69]) and rate of ≥VGPR (62.9% vs 24.0%, OR 5.37 [95% CI 3.61-8.49]) compared with ECA regimens. Conclusion Despite current use of novel therapies, there is no well-established RW standard of care (SOC) for patients with TCE RRMM treated at IMWG sites. To our knowledge, this is the first RW ECA study in MM with a high percentage of anti-BCMA therapies and response ascertainment for all patients by ICRC. Linvoseltamab induced significantly higher response rates, including rate of ≥VGPR, compared with current RW SOC therapies, highlighting its potential as a highly effective treatment in patients with TCE RRMM.

Classic Hodgkin Lymphoma (cHL) is characterized by the presence of abnormal large cells known as Hodgkin Reed-Sternberg (HRS) cells. Curative intent chemotherapy has a 90% response rate, but for refractory patients, current immunotherapies remain insufficient. Ongoing research aims to enhance therapy and patient outcomes by focusing on the tumor microenvironment (TME), a complex environment that includes diverse non-malignant cells, including immune cells, which constitute a critical component of the TME. Utilizing multiplex analysis to comprehend these intricate interactions can pave the way for identifying novel strategies to combat cancer more effectively. CD30-targeted therapies and PD1/PDL1 inhibitors are under investigation clinically and could potentially benefit from adding checkpoint markers such as TIM-3 to enhance patient outcomes by addressing T-cell exhaustion. Such combination strategies will require assays and analysis strategies that can describe both spatial and multi-marker data. Multiplex immunofluorescence (mIF) is a valuable tool for analyzing spatial biology, patient selection, mechanism of action, pharmacodynamics and biomarker assays predictive of response. Describing the relationship between T cell exhaustion and response in cHL may guide the development of targeted treatments aimed at restoring the immune system's ability to recognize and eliminate cancer cells. Twenty-five to thirty percent of cHL patients with advanced stages do not respond to standard therapies. To understand the mechanisms of resistance, we developed a mIF panel (CD4, CD8, CD30, PD-1, PD-L1, and TIM3) for formalin-fixed and paraffin-embedded cHL tissues on the OPAL Tyramide Signal Amplification system and the Leica Bond RX. A set of commercially sourced cHL whole tissue samples (n=5) were used to develop and validate the panel, with qualitative evaluations by a Hematopathologist affirming that the mIF and 3, 3'-diaminobenzidine (DAB) staining yielded comparable results. Subsequently, a cohort of cHL samples (n=34) were stained and underwent exploratory image (Halo) and data (Microsoft Excel and R Studio) analyses. The image analysis strategy includes cell segmentation and phenotyping for all markers in the panel, identifying individual cell populations and multi-marker co-expressing cell populations. Additionally, spatial analysis describes the relationships between key phenotypes in the TME. The quantity of exhausted T cells, their average distance to HRS cells and the average count of exhausted T cells within different proximities of HRS cells will be presented. The development of this mIF assay for cHL demonstrates its consistent application at a mid-scale level across a diverse patient population with varying medical backgrounds and treatment histories. This approach provides a deeper understanding of immune response diversity and cellular composition within cHL. Future deployment of the panel against clinical trial samples with outcomes and responses will yield further insights.

Background: Chemoimmunotherapy using rituximab, cyclophosphamide, doxorubicin hydrochloride (hydroxydaunomycin), vincristine sulfate (Oncovin), and prednisone (R-CHOP) has been the standard of care treatment of DLBCL for over 20 years. Despite its widespread usage, there is no accepted standard for the dose of prednisone in this setting which varies from fixed-dose (100 mg daily for 5 days) to different levels of BSA-adjusted dosage (ranging from 40-100 mg/m2 daily for 5 days). BSA-adjusted dosage results in high doses of prednisone administered to patients with increased body surface area which may lead to significant adverse events. We performed a systematic review and meta-analysis to determine if fixed-dose prednisone during R-CHOP therapy results in equivalent outcomes compared to BSA-adjusted dosing. Methods: A comprehensive search of several databases from each database's inception to April 29th, 2024, English language, was conducted. The databases included Ovid MEDLINE and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, and Daily, Ovid EMBASE, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Scopus. The search strategy was designed and conducted by an experienced librarian with input from the study's principal investigator. Controlled vocabulary supplemented with keywords was used to search for prospective clinical studies of R-CHOP for adult patients with untreated DLBCL. Search results were reviewed independently by 2 members of the study team for final inclusion. Discrepancies were adjudicated by a third member and reviewed by the senior author. Prednisone dosage and clinical outcomes were abstracted from the available public data. Meta-analysis was performed using the metafor package in R version 4.2.2 by applying a mixed-effects model to combine results from the multiple studies. The analysis was first conducted overall to determine the general effect, and then stratified by prednisone dose (fixed- vs. BSA-adjusted) to explore dose-dependent variations in outcomes. Results: Our search resulted in 2287 entries which were individually reviewed by the study team. A total of 30 studies with a combined sample size of 3573 treated patients fulfilled the inclusion criteria and were included in the final analysis set. Nineteen (63%) studies with a combined sample size of 1930 patients (median 155, range 12-399) used fixed-dose prednisone. Eleven (37%) studies with a combined sample size of 1643 patients (median 70, range 9-439) used BSA-adjusted dosing. Overall survival (OS) at 2 years data were available for 11 (37%) of the studies. Progression free survival (PFS) at 2 years data were available for 8 studies (27%). Overall response rate (ORR) and complete response rate (CRR) data were available for 16 (54%) and 14 (47%) of the included studies, respectively. OS at 2 years for all studies was 84% (SD 78%-91%) and did not differ between fixed-dose (88%, SD 79%-97%) and BSA-adjusted dose (82%, 73%-91%). PFS at 2 years for all studies was 77% (SD 68%-85%) and did not differ between fixed-dose (80%, SD 68%-93%) and BSA-adjusted dose (74%, SD 62%-86%). ORR for all studies was 86% (SD 79%-92%) and did not differ between fixed-dose (86%, SD 76%-96%) and BSA-adjusted dosage (84%, SD 80%-88%). CRR for all studies was 70% (SD 61%-80%) and did not differ between fixed-dose (67%, SD 54%-81%) and BSA-adjusted dose (77%, SD 64%-89%). Heterogeneity tests performed according to available clinical outcomes yielded results between 0% and 76%. Conclusion: The result of our systematic review and meta-analysis combining 30 prospective studies and a total of 3573 patients with newly diagnosed DLBCL treated with frontline R-CHOP found no difference in clinical outcomes between patients treated with fixed-dose and BSA-adjusted dose prednisone. Our findings provide scientific evidence for the widespread practice of capping prednisone at the maximum dose of 100 mg daily for 5 days, potentially avoiding unnecessary adverse effects from BSA-adjusted dosing.

Background/Case Studies: A 79-year-old male was admitted to our institution with anemia, with a hemoglobin nadir of 5.5g/dL, and no recent transfusion history. Given a remote history of occult colonic bleeding, the working diagnosis was GI bleeding. The referring blood bank had reported “possible antibody to high prevalence antigens of the Kell system, suspected McLeod.” The American Rare Donor Program had been contacted and confirmed no Ku or KX negative blood was available in the United States. Study Design/Methods: Initial testing by our immunohematology reference lab showed that the patient's plasma reacted with all cells tested, including the patient's own red blood cells (RBCs). The patient had a positive DAT (W+ poly, W+ IgG and negative C3d). Further testing showed the plasma and eluate prepared from the patient's RBCs did not react with cells treated with dithiothreitol (DTT) and did not react with an RBC designated as K0. Red cell morphology and creatinine kinase measurements were not consistent with the McLeod phenotype. The antibody was interpreted as having anti-Ku specificity. A serologic phenotype was performed on the patient's RBCs following treatment with chloroquine diphosphate and showed the following results: K-k-, Kp(b-), Js(b-) and Ku-. A molecular phenotype using Immucor Precise type gave the following results: K-k+, Kp(a-b+), Js(a-b+). Results/Findings: A sample was sent to the American Red Cross National Molecular Laboratory for KEL-cDNA analysis and genotype for KX blood group system. The probable genotype was KEL*02/KEL*02 with a predicted phenotype of K-k+, Kp(a-b+), Js(a-b+). The probable genotype was XK*01 (homozygous or hemizygous) with a predicted phenotype of Kx+. Given the positive DAT and the absence of an identifiable source of GI bleeding, a diagnosis of autoimmune hemolytic anemia with suppression of Kell system antigens was made. The patient was initially treated with 100mg oral prednisone daily for two weeks with subsequent weekly taper, four doses of 1g/kg IVIg daily, four doses of rituximab weekly, and three doses of daratumumab on weeks 1, 2 and 4. During the initial work-up and treatment, the patient did not receive a transfusion. Testing was repeated 3 months later: the DAT remained W+ and the antibody reactivity now demonstrated apparent anti-Jsb specificity. However, serologic antigen typing using chloroquine diphosphate now showed the following results: k+, Kp(b+), Js(b+) and Ku+. At this time, the patient's hemoglobin increased to a maximum of 11.6g/dL. Unfortunately, the patient relapsed about 4.5 months after his initial presentation. He was restarted on 100mg oral prednisone daily for two weeks followed by weekly taper. This led to only a modest improvement in his hemoglobin concentration. The DAT and phenotyping results remained unchanged but the antibody identification now demonstrated apparent anti-k (Cellano) specificity during this period. As the patient continued to have symptomatic anemia, in the setting of massive splenomegaly, the was decision made to proceed to splenectomy. During the operation, the patient received two K- units that were otherwise not typed for additional Kell system antigens. In the four weeks post-transfusion, there was no evidence of an acute worsening of his hemolytic anemia. Conclusions: This is a case of an autoantibody with apparent specificity to a high prevalence KEL antigen(s). The antibody was originally thought to be an alloantibody, requiring Ku- or Kx- RBCs. The KEL system antigens were depressed due to the patient's disease state and were re-expressed following treatment with multimodal immunomodulatory treatment. Specificity of the antibody appeared to change during therapy reacting more strongly with different high incidence Kell system antigens. When the patient was transfused with K- RBCs later in his disease course, there was no acute worsening of hemolysis. This finding is consistent with an autoantibody rather than an alloantibody to KEL antigen(s). This case shows the importance of incorporating molecular testing along with serology.

We report the second known case in the world of a rare beta chain variant hemoglobinopathy Hemoglobin Little Venice [β42 Phe→Cys, HBB:c.128T>G] originally found in 2009 in a 7 month-old Asian Indian female with severe chronic hemolytic anemia during infancy who is now 15 years of age. Her newborn hemoglobinopathy screen showed FA. She presented with jaundice at 1 month of age with a bilirubin of 15 mg/dL initially attributed to breast milk and was managed with supportive care. Hemoglobin electrophoresis with confirmatory DNA sequencing was performed by Mayo Clinic laboratories at 7 months of age to establish the diagnosis. At that time hemoglobin was 5.6 g/dL and bilirubin was 6.9 mg/dL. Hemoglobin electrophoresis showed Hb A 71.6%, Hb A2 2.5%, Hb F 24.5% and Hb variant 1.4%. Stability studies were abnormal. The testing revealed a previously undescribed beta 42 mutation of TTT>TGT (Phe>Cys). Our patient has been receiving blood transfusions every four weeks leading to iron overload at 5 years of age treated with an iron chelator. Her growth and development have been normal, similar to peers. At age 9, she had cholecystectomy for gallstones. At the age of 11, she had SARS COVID-19 infection that was treated with supportive care and she recovered well. She was noted to have mild thrombocytopenia ranging from 70-110's and had splenectomy at 13 due to increased frequency of blood transfusion and chronic splenomegaly. At 14, she was treated for asymptomatic babesiosis with atovaquone and azithromycin. At present, she continues to require regular transfusions every 4 weeks due to severe hemolytic anemia and has significant thrombocytosis along with leukocytosis and nucleated red blood cells. She has significant transfusion-associated hemosiderosis and receives double chelation with deferasirox and deferiprone with marked history of noncompliance. Last MRI of Liver T2* in 2023 showed an approximate hepatic iron concentration of greater than 20 mg/g that is significantly elevated and MRI of heart T2*decay time of greater than 20 ms, which indicates low risk of clinically significant myocardial iron deposition. Both parents and two sisters have no evidence of hemolytic anemia and there are no other family members with chronic anemia or history of splenectomies. The importance of phenylalanine in position 42 was described by Bartram et al in 2012 for the position's role in maintaining the solubility and stability of the β-hemoglobin chain. When replaced with cysteine, it disrupts oxygen delivery to the cells. This rare hemoglobinopathy requires multiple transfusions to treat vaso-occlusive episodes. At present, little is known regarding treatment choices for this rare hemoglobinopathy therefore, we will continue chronic blood transfusions and encourage compliance with iron chelation. A similar variant affecting the same codon, Hb Hammersmith [β42 Phe→Ser, HBB:c.128T>C] has comparatively more data in the literature which may offer some general guidance.

Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy, driven by IgG antibodies (Abs) that target platelet factor 4 (PF4) bound to heparin, resulting in platelet activation and a pro-thrombotic state. The PF4/Heparin (PF4/H) ELISA is the most commonly used screening assay for HIT due to its wide accessibility and high sensitivity. Despite its limited specificity, resulting in only a small fraction of positive cases progressing to actual HIT, PF4/H ELISA remains a critical tool in initial diagnostics. It is generally believed that HIT patients produce two types of Abs - those that bind to PF4/H and may or may not activate platelets. However, there are documented but rare HIT cases with an atypical profile: Abs testing negative in the PF4/H ELISA (ELISA-) but capable of platelet activation, suggesting the presence of a third type of Abs - those that activate platelets but can't recognize PF4/H complex. Since a PF4/H ELISA- result typically excludes an HIT diagnosis, overseeing these cases could lead to the resumption of heparin, potentially resulting in life-threatening thrombosis. Additionally, in HIT cases with a positive ELISA test profile, or classic HIT cases, levels of platelet-activating Abs and PF4/H-reactive Abs are not always correlated, suggesting the presence of ELISA- platelet-activating Abs. We thus investigated whether ELISA- platelet-activating Abs are present in classic HIT. To identify and characterize ELISA- Abs at the serological level, we firstly purified IgG Abs from the plasma of 5 healthy donors (HD) and 8 HIT patients using protein A beads, followed by the depletion of PF4/H-binding Abs using PF4/H-coated Sepharose beads. The efficiency of IgG purification and PF4/H-specific IgG depletion was confirmed by IgG and PF4/H ELISA. P-selectin expression assay (PEA) was conducted to evaluate the platelet activating ability of purified IgG pre and post depletion of PF4/H-specific Abs. We found that variable, but significant levels of platelet-activating Abs exist in the PF4/H non-reactive IgG portion in all 8 HIT samples, but none of the HD samples. Closely resembling those found in the PF4/H-reactive Abs in HIT patients' plasma, platelet activation induced by post-depletion Abs relied on exogenous PF4 and FcγRIIa and was inhibited by high-dose heparin. These data demonstrate that PF4/H non-reactive IgG Abs coexist with PF4/H-reactive Abs and may contribute to platelet activation in HIT patients. To verify these findings at the clonal level, we conducted single B-cell culture to induce antibody secretion by the cultured B cells from patients experiencing clinical manifestations of HIT. We screened clonal Abs made by 1506 single IgG1+ B cells isolated from peripheral blood mononuclear cells (PBMCs) of seven HIT patients and identified 18 clones capable of platelet activation. Of these, 13 were unable to bind to PF4/H. The functionality of these Abs was confirmed by recombinant Abs derived from single B-cell clones. This finding suggests that PF4/H non-reactive platelet-activating Abs exist at a higher frequency than those that bind to PF4/H. Interestingly, even though these Abs tested negative in the PF4/H ELISA, they were able to bind to the surface of PF4-treated platelets, and their platelet activation ability correlated with platelet binding affinity, suggesting a potential method for their detection. In summary, our study identified a novel group of potentially pathogenic Abs in HIT that, while unable to recognize the PF4/H complex, can bind to the PF4-coated platelet surface. These Abs frequently coexist with PF4/H-binding pathogenic Abs and may contribute to HIT pathogenesis. These insights will enrich our understanding of HIT pathogenesis and may pave the way for more advanced diagnostic and therapeutic strategies.

Introduction: Red blood cell (RBC) transfusion is a lifesaving intervention with a low but persistent risk of transfusion-transmitted infection. Amustaline/glutathione RBC pathogen-reduction (PR) technology is designed to proactively inactivate a broad spectrum of viruses, bacteria, protozoa and leukocytes by chemically crosslinking nucleic acids and preventing replication and transcription. The Red Cell Pathogen Inactivation (ReCePI) trial was a Phase III, double-blinded, randomized non-inferiority study comparing PR and conventional RBCs for the support of acute anemia. Methods/Study Design: Complex cardiac or thoracic-aorta surgery patients received conventional (Control) or PR RBCs (Test) during and for 7 days after surgery. The protocol was conducted with ethics committee approval at all participating centers and written informed consent from all participants. Hemoglobin levels, blood utilization and serum creatinine were assessed as indicators of efficacy and oxygenation of tissues (Karkouti et al. Br J Anaesth. 2012; 109 Suppl 1: i29-i38). The primary endpoint was the incidence of acute kidney injury (AKI) measured as change in serum creatinine from baseline within 48 hours of surgery, a predictor of adverse postoperative outcomes including mortality by Day 30 post-surgery (Lassnig et al. Am Soc Nephrol 2004; 1597-1605). Secondary endpoints included AKI occurring up to 7 days post-surgery (KDIGO Clinical Practice Guideline for AKI, Kidney Inter, Suppl. 2012;2:1-138); death or the need for renal replacement therapy by 30 days post-surgery; PR RBC-specific antibodies; and death by day 75 post-surgery. With >292 subjects enrolled, the study had 80% power to demonstrate non-inferiority, assuming an AKI incidence of 30% with conventional RBCs and a non-inferiority margin of half the conventional RBC rate. Under these circumstances, an absolute treatment increase of 5% in the AKI rate in the PR RBC arm would fail the non-inferiority test. This work was supported by a contract with the US Biomedical Advanced Research and Development Authority (HHS010020160009c) with Cerus Corporation. Results: Five-hundred and eighty-one subjects were randomized and 321 (55%) transfused in 18 US hospitals. In the modified intent-to-treat analysis subjects receiving Test and Control RBCs had similar median [IQR] total blood loss (1500 [940-2475] mL Test, 1733 [1060-2880] mL Control, p=0.310) and comparable median hemoglobin levels at baseline and immediately post-surgery (9.8 [8.9-10.9] g/dL Test, 9.6 [8.6-10.6] g/dL Control, p=0.157) and for 7 days after surgery, The PR RBC arm was transfused with fewer RBCs, measured as total RBC Hb transfused over 7-days (169.0 [102.0-240.0] g Hb PR arm, 188.0 [126.0-295.0] g Hb, conventional RBC arm, p=0.008). The incidence of AKI was 29.3% (46/157) for Test and 28.0% (45/161) for Control. The treatment difference was 0.74% (95% CI -8.9, 10.4%, non-inferiority margin 14.0%, p=0.001 for non-inferiority). Non-inferiority was also achieved by the per protocol analysis. Average mean change in serum creatinine within 48 hours of surgery was comparable (Test 0.020, Control 0.23 mg/dL, P=0.515). Adverse events, serious adverse events and deaths on study were not different. Five of 159 (3.1%) PR RBC recipients developed low titer PR RBC-specific antibodies without clinical signs of hemolysis. Flow cytometry analysis revealed persistent circulating PR RBCs with uniform antigen loss (modulation). Low level human IgG antibody binding was demonstrated in 3 of 5 subjects. Conclusions: PR RBCs showed equivalent hemoglobin support for acute bleeding patients undergoing cardiac or thoracic-aorta surgery while using less transfused total RBC Hb over 7 days. The incidence of AKI in patients transfused with PR RBCs was non-inferior to that observed with conventional RBCs, indicative of effective tissue oxygenation. Treatment-related antibodies to PR-RBC were observed only in Test subjects, the antibodies were low titer, transient, without clinical hemolysis, and persistent circulating PR RBCs were detected with modulated low level acridine antigen expression (www.clinicaltrials.gov #NCT03459287).

Introduction: Post-Cardiopulmonary Bypass (CPB) coagulopathy results in bleeding, transfusion and re-exploration, and increases morbidity, mortality and cost. Some studies have reported a relationship between individual factor levels and chest tube drainage as a marker of bleeding, but few have reported that relationship for multiple factors. Methods: With IRB approval and informed consent, 98 patients, ages 18 - 85, undergoing cardiac surgery with cardiopulmonary bypass (CPB) were studied. Factor levels measured five minutes post-protamine included fibrinogen (FIB), and factors II, V, VII, VIII, Von Willebrand Factor Antigen (VWF Ag), Ristocetin Cofactor (VWF Activity), IX, X, XI and XIII. Linear regression models examined the relationship between factor levels and post-op chest tube drainage over 24 hours as a surrogate marker for bleeding. An effect size (ES) was calculated so that each factor deficiency multiplied by the ES and the patient's weight in kg would estimate the contribution of that factor to bleeding. Factors were ranked from most to least impact on bleeding. Conversely, said ES would estimate the decrease in bleeding achieved by a percentage increase in a deficient factor level if such factor was known to be deficient. Results: F:II was 1st (most associated with bleeding), ES = -0.137, 95% CI -0.214 - -0.059, p < 0.001; F:X was 2nd, ES = -0.130, 95% CI -0.202 - -0.058, p < 0.001; F:VII ES = -0.121, 95% CI -0.198 - -0.045, p = 0.002; F:XI ES = -0.109, 95% CI -0.16 - -0.058, p < 0.001; F:IX ES = -0.100; 95% CI -0.135 - -0.065, p < 0.001; F:V ES = - 0.065; 95% CI -0.114 - -0.016, p = 0.011; F:XIII ES = - 0.055; 95% CI -0.099 - -0.011, p = 0.016; FIB ES = - 0.042; 95% CI -0.063 - -0.022, p < 0.001; F:VIII ES = - 0.007; 95% CI -0.020 - 0.006, p = 0.318; VWF Ag ES = 0.002; 95% CI -0.016 - 0.019, p = 0.855; VWF Activity ES = 0.004; 95% CI -0.015 - 0.023, p = 0.671. Conclusions: Factors VIII, VWF Ag and Ristocetin Cofactor demonstrated no relationship with bleeding, perhaps because they are elevated as acute-phase reactants. In theory, raising F:II level post-CPB by 30% in an 80 kg patient might decrease bleeding by 328 ml, and raising F:X level post-CPB by 30% in an 80 kg patient might decrease bleeding by 312 ml, etc. A weakness of this study is that the sample size was too small to perform a multi-variate analysis considering all factor levels. Still, the data suggest four-factor prothrombin complex concentrate (PCC) might be a more effective treatment for post-CPB coagulopathy than FFP. The data do not confirm cause and effect; that would require a large study with control and treatment arms. If multiple factor levels could be measured in a rapid and cost-effective manner it might aid in targeted treatment of post-CPB coagulopathy. The data suggest that work should be performed to better elucidate the contribution of coagulation factor deficiencies to post-CPB bleeding, as improved treatment of such factor deficiencies might decrease bleeding and transfusion requirements.