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Monoclonal gammopathy of thrombotic significance (MGTS) is a recently recognized thrombophilia characterized by the production of a monoclonal antibody that binds to platelet factor 4 (PF4) and stimulates platelet activation (Blood. 2022 Jul 7;140(1):73-77). Typical signs of MGTS include a history of recurrent thrombosis, persistent thrombocytopenia, and positive laboratory results in PF4/polyanion enzyme-linked immunosorbent assay (ELISA) and serotonin release assay (SRA) testing, as in the related thrombotic disorder heparin-induced thrombocytopenia (HIT). Here, we present a case of MGTS, presenting with transient thrombocytopenia coincident with thrombotic episodes and negative test results in SRA and PF4/polyanion-based testing platforms (ELISAs and automated assays). A 56-year-old male patient initially presented with acute left lower extremity deep vein thrombosis (DVT) and a pulmonary embolism. Following the administration of warfarin, the patient experienced a second DVT four months later and was transitioned to a factor Xa inhibitor. Fifty-two months later, the patient developed occlusion of the splenic and superior mesenteric veins despite additional anticoagulation therapy. Further testing led to a diagnosis of an IgG2 kappa monoclonal gammopathy of undetermined significance (MGUS). Eleven months later, the patient again suffered breakthrough thrombosis, specifically radial artery thrombosis, and a thrombotic cerebrovascular accident, leading to the addition of aspirin to the patient's treatment regimen. Notably, where detailed blood counts were available in the patient's clinical history, the patient experienced only transient thrombocytopenia coinciding with his two most recent thrombotic episodes and has had platelet counts in the normal range in the four-year period since his last thrombotic event. After initiating dual anticoagulant/antiplatelet therapy, the patient has not developed recurrent thrombocytopenia or new thrombotic events. Antigen-based and functional testing for HIT antibodies (ELISA, SRA, and automated immunoassays) were negative in this patient, unlike in the previously described index case of MGTS, where serological testing mimicked classical HIT serology (i.e., HIT ELISA and SRA positivity). The sample was also non-reactive in a vaccine-induced immune thrombotic thrombocytopenia (VITT)-specific ELISA employing uncomplexed PF4 targets, as previously described (Am J Hematol. 2022 May;97(5):519-526). Conversely, the patient's antibody consistently stimulated platelet activation in a PF4- and IgG-dependent manner in functional testing using PF4-treated platelets. This included PF4-treated platelets that were freshly isolated and used in the PF4-dependent P-selectin expression assay (PEA) and cryopreserved platelets used in the thrombospondin-1 release assay. Interestingly, consistently positive PEA results have been documented from four samples over the last four years, during which the patient had normal platelet counts. To further characterize the patient's IgG2 MGUS antibody, the patient's monoclonal was immuno-enriched. Patient sera and the immuno-enriched MGUS were then compared by mass spectrometry, which generated identical mass profiles. After confirming the effective enrichment of the patient's MGUS by mass spectrometry, the antibody was de novo sequenced or “reverse-engineered” to obtain the antibody's amino acid sequence. The antibody was then expressed and tested in ELISA-based and functional platelet assays. Importantly, the recombinant antibody replicated the PF4-dependent platelet activation observed with patient serum and did not bind PF4/polyanion targets in ELISA testing. Together, these data strongly support the identification of a new class of ELISA- and SRA-negative anti-PF4 monoclonal antibodies that cause MGTS. This case illustrates the diagnostic challenges in MGTS. MGTS patients may not exhibit persistent thrombocytopenia, and diagnostic tests for detecting HIT antibodies may be ineffective in accurately diagnosing this new thrombophilia. This case emphasizes the importance of reviewing platelet counts in the peri-thrombotic period to recognize transient thrombocytopenia and establishes the utility of PF4-enhanced functional assays to detect pathogenic anti-PF4 antibodies, even in settings where classical HIT testing (i.e., ELISA/SRA) is negative.

Introduction Establishment of reference intervals (RI) for quantitative assays requires a minimum of 120 qualified normal donor (ND) samples for each partition of an analyte. Based on CLSI EP28 A3C guideline [CLSI. Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; Approved Guideline-Third Edition. CLSI document EP28-A3c. Wayne, PA: Clinical and Laboratory Standards Institute; 2008.], verification of previously established and/or published RI can be performed with a minimum of 20 NDs, especially given complexities of finding qualified NDs. Reagent manufacturers typically provide adult RI, thus facilitating RI verification as a viable option. NDs for the Pediatric (Peds) (<18 years of age) population are difficult to obtain, published RIs are performed with sample cohorts less than the suggested number or only performed with specific instrument/reagent combinations. Herein, we report our experiences with Peds RI. Methods After IRB approval, healthy pediatric outpatients ages 0-18yrs were recruited and consented. Plasma obtained from umbilical cord, finger/heel/ear stick, or venipuncture blood samples (no more than 50 mL or 3 mL per kg) and collected in 3.2% sodium citrate. Assays included Protein (P) C antigen (PCAG) and chromogenic activity (PCFX); P S total (PST), free (PSF) antigen, and functional (SFX); antithrombin antigen (ATAG) and chromogenic activity (ATFX); plasminogen (PLGN) and alpha-2-plasmin inhibitor (A2PI). Assay kits were PCFX - HemosIL® (Werfen, Beford, MA) Protein C, PST - LIATEST® (Diagnostica Stago S.A.S., Asnières sur Seine, France) Protein S, PSF - HemosIL® Free Protein S, SFX - HemosIL® Protein S Activity, ATAG - LIATEST® AT III , ATFX - HemosIL® Liquid Antithrombin, PLGN - HemosIL® Plasminogen, and A2PI - HemosIL® Plasmin Inhibitor performed on the ACL TOP 700 (Werfen) instrument. PCAG - REAADS® Protein C Antigen Test Kit (Corgenix, Inc. Broomfield, CO) was performed on the Janus G3 liquid handler (Revvity, Waltham, MA) and Synergy Neo2 microplate reader (Agilent, Santa Clara, CA). Assay mean and range were calculated. Results Insufficient numbers of patients <1yr were collected. Type of assay, age range in yr and number of samples (n), assay mean in % and range results respectively were as follows: PCAG 1-5 (n=15) 87(46-146); 5-10 (n=82) 81 (45-158); 10-15 (n=169) 84 (44-157); 15-18 (n=107) 91 (57-149). PCFX 1-5 (n=20) 97 (56-140); 5-10 (n=84) 89 (62-135); 10-15 (n=188) 91 (55-140); 15-18 (n=124) 96 (54-138). PST (males): 1-5 (n=10) 120 (96-145); 5-10 (n=46) 108 (75-150); 10-15 (n=91) 111 (80-168); 15-18 (n=63) 113 (72-184). PST (females): 1-5 (n=9) 104 (67-146); 5-10 (n=37) 111 (81-159); Ages 10-15 (n=94) 107 (78-153); 15-18 (n=63) 101 (65-148). PSF (males): 1-5 (n=10) 94 (74-109); 5-10 (n=47) 101 (66-141); 10-15 (n=93) 101 (69-151); 15-18 (n=62) 111 (74-187). PSF (females): 1-5 (n=9) 78 (9-124); 5-10 (n=37) 107 (79-137); 10-15 (n=95) 99 (63-138); 15-18 (n=63) 97 (60-132). SFX (males): 1-5 (n=9) 100 (85-128); 5-10 (n=48) 104 (66-144); 10-15 (n=93) 103 (66-168); 15-18 (n=59) 109 (72-157). SFX (females): 1-5 (n=8) 94 (18-121); 5-10 (n=37) 107 (81-143); 10-15 (n=90) 101 (65-147); 15-18 (n=60) 97 (53-135). ATAG 1-5 (n=19) 104 (80-121); 5-10 (n=83) 104 (78-121); 10-15 (n=188) 104 (66-126); 15-18 (n=126) 101 (67-126). ATFX 1-5 (n=20) 112 (94-135); 5-10 (n=84) 107 (87-123); 10-15 (n=188) 105 (84-138); 15-18 (n=126) 101 (84-129). PLGN 1-5 (n=17) 96 (76-124); 5-10 (n=85) 88 (65-125); 10-15 (n=183) 90 (49-151); 15-18 (n=119) 94 (64-151). A2PI: 1-5 (n=17) 134 (118-151); 5-10 (n=85) 126 (107-139); 10-15 (n=183) 121 (104-140); 15-18 (n=118) 116 (91-143). Conclusions Based on CLSI EP28 A3C criteria for verification, no more than 10% of results should fall outside of established/published RI, for example adult RI. Thus, compared to the SCL adult RI, PLGN assay meets criteria in all age ranges and no additional ND are needed. For the remaining assays, additional ND for ages 1-5 are needed. For ages 5-18 criteria for verification are satisfied for all analytes except PCAG. PCAG has 27, 61, and 19 patients falling below lower RI for ages 5-10, 10-15, and 15-18, respectively.

Trauma-induced coagulopathy (TIC) is common after injury and reliable quantification of its severity is lacking. The objective of this study was to evaluate whether thrombin generation would be significantly altered if whole blood samples from trauma patients were collected without (citrate-only) and with corn trypsin inhibitor (CTI+). In a prospective cohort study, 36 trauma pts presenting to a Level I Trauma Center within 12 hours of injury, had whole blood collected simultaneously in citrate-only (3.2%) and citrated plus CTI (CTI+ [final 25 ug/mL]), and processed to platelet free plasma by double centrifugation (3000g, 15 minutes). Samples were stored at -80C with no thawing until analysis. Thrombin generation profiles were measured using the ST Genesia assay (Diagnostica STAGO SAS) and parameters included endogenous thrombin potential (ETP), lag time (LT), peak height, start of tail, velocity index, and time to peak (ttPeak) were analyzed for trauma pts. Data presented as median [IQR] or n (%), with paired t-test and Spearman's correlation analysis were performed between citrated non-CTI and citrated CTI spiked blood samples, with p-value <0.05 statistically significant. Pts presented with significant injury ISS 13 [5, 21], age 45 [29, 59] years, 80.6% male, BMI 26.9 [25.4, 28.3], 94.4% blunt trauma, 22.3% had surgery by day 1 of admission. Significant differences were found between the citrated-only and CTI +tubes in several thrombin generation parameters: ETP (1339 Nm*min [1172.5,1417], 1124.5 [925.4,1285], p<0.001), peak height (222.3 Nm [186.0, 275.6], 160.6 [132.7,208.3], p<0.001), ttPeak (5.64 min [4.86,6.63], 6.19 [5.36, 7.34], p<0.001), start of tail (19.4 min [17.6,21.3], 21.6 [18.9, 23.6], p=0.014), and velocity index (117.6 Nm/min [77.9, 163.1], 71.9 [54.9,106.0], p<0.001). However, LT (3.14 min [2.74, 3.90], 3.08 [2.84, 3.96], p=0.665) did not show a statistically significant difference. Spearman's correlation analysis showed high correlation between citrate-only and CTI+ citrated plasma samples, with Spearman's rank correlation coefficients for LT (0.941), peak height (0.760), ttPeak (0.928), ETP (0.770), start of tail (0.869), and velocity index (0.766) respectively. The results suggest that use of CTI+ decrease thrombin generation kinetics from blood samples obtained from trauma patients. These findings underscore the need for careful consideration of sample collection and processing for use of thrombin generation assays in clinical setting. However, there is very strong correlation of the thrombin parameters obtained from citrated-only plasma to CTI+ plasma samples, suggesting they capture similar information. CTI-spiked citrated tubes appear to reduce contact activation with respect to thrombin generation profiles compared to standard citrated only tubes. This should be a consideration for platform-based lab processing of thrombin generation assays for assessment of coagulopathy after injury; however, given the cost of CTI, citrated-only tubes can be an option for characterization of thrombin generation profile in clinical samples.

Introduction: Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, life-threatening hematological disorder affecting approximately 24 people per million in the United States (US). Iptacopan, the first orally administered monotherapy for PNH, received US Food and Drug Administration approval in December 2023. APPRISE-PNH (A Patient Platform for Real-world data on Iptacopan in the United StatEs for patients with PNH) is a data platform designed to capture comprehensive real-world information on patients with PNH treated with iptacopan in the US. This interim analysis aims to provide early insights into the characteristics and treatment patterns of patients enrolled in APPRISE-PNH to date. Methods: APPRISE-PNH is a retrospective, longitudinal, data platform including adult patients (age ≥18 years) with PNH treated with iptacopan in the US real-world setting. Consenting patients in the US are recruited through the iptacopan distribution network. The present analysis includes data from patients enrolled between July 2 and July 26, 2024, with additional data collection expected through the remainder of 2024 and 2025. Patient characteristics and treatment patterns were evaluated descriptively. Duration of therapy was measured from the date of iptacopan initiation until the date of iptacopan discontinuation or data cut-off, whichever occurred first. Treatment adherence was measured using both the medication possession ratio (MPR), calculated as the ratio of the total days supply to days covered, and the proportion of days covered (PDC), calculated as the ratio of days with supply to days covered. Results: As of July 26th, 2024, nine patients with PNH have enrolled in the APPRISE-PNH data platform. The median age at the start of iptacopan therapy was 44 years (interquartile range [IQR] 40-73 years), seven (78%) patients were female, and four (44%) were covered by commercial insurance. Overall, two (22%) patients were treatment-naïve at the start of iptacopan therapy, while seven (78%) patients had received prior complement-inhibitor (CI) therapy for PNH (44% ravulizumab, 44% eculizumab, 33% pegcetacoplan). The median duration of iptacopan therapy was 2.0 months (IQR 1.5-2.9 months). All patients received iptacopan 200 mg twice daily (as per the product label) and the median number of fills was 2.0 (IQR 1.0-3.0). At the time of data cut-off, no patients had discontinued iptacopan therapy. The MPR in this group of patients was 136% (IQR 114%-150%) and PDC was 100% (IQR 100%-100%). Conclusions: These are the first data from the APPRISE-PNH data platform and represent the first insights into real-world use of iptacopan in the US. Many patients enrolled in APPRISE-PNH had previously received CI therapy for PNH. Treatment adherence, as indicated by both the MPR and PDC, was high across iptacopan-treated patients. Enrollment into the APPRISE-PNH data platform is currently ongoing; data from additional patients, additional laboratory and clinical outcomes, and longer follow-up data are expected to be available at the time of presentation.

Background: Due to recent advances, patients with follicular lymphoma (FL) have multiple treatment options with high response rates and durability. However, there is a gap in understanding how patient preferences influence treatment selection. To close this gap, we conducted a qualitative study using focus groups of adults with FL to understand their knowledge of treatment options, priorities, and decision-making process. We designed this study to inform the content of a planned discrete choice experiment in a larger population of patients with FL to better understand patient preferences and trade-offs around treatment delivery, side effects, outcomes, and quality of life. Methods: We conducted focus groups lasting 60-90 minutes, each with 3-5 participants recruited from the Lymphoma Epidemiology of Outcomes (LEO) Cohort Study. The LEO Cohort Study is a multi-institutional prospective cohort study of newly diagnosed adults with non-Hodgkin lymphoma from July 2015 to present. Each focus group was co-led by two investigators (U.D. and M.T.) and conducted using Zoom video technology. Participants were asked to comment on their understanding about FL and available treatments, their ideal treatment, their decision-making process about prior therapies, and quality of life and side effects associated with treatment. We performed exploratory content analysis of participant understanding of FL and their treatment preferences. We will continue to conduct focus groups until we reach thematic saturation, which we anticipate will occur with one additional focus group. Themes from all focus groups were identified and agreed upon by both investigators (U.D. and M.T.) and were verified by additional investigators (J.D., M.L, M.H., B.K.L, C.C., M.M.). Results: To date, we conducted five focus groups with a total of N=21 participants (median age 60 [range 41-88], 66.7% female, 71.4% non-Hispanic White, 14.3% Hispanic, 9.5% Asian, 4.8% Black/Hispanic). We identified the following themes and representative quotes: 1) Holistic approach:Participants wanted their oncologists to view their care from a holistic perspective, discussing their individual priorities and options that would accommodate their fitness routine and ability to work. “[I wish] if doctors can consider not just the physical choices, but also the mental and emotional choices as well, the holistic person.” - Participant 13 “There's zero chance I can go back to working in the type of career where other people rely on me for things. I can't keep things straight.” - Participant 16 2) Ideal treatment:An ideal treatment would limit impact on fatigue, cognitive function, and have minimal toxicity to preserve quality of life and an active lifestyle. “I would say something that has minimal impact on daily life would be ideal and something that would make you feel better.” - Participant 6 3) Shared decision-making: Participants wanted to be better informed about available treatment options and often utilized second opinions to inform their decisions. “It helped to get the second opinion versus not. It would've been a completely different set of events.” - Participant 17 4) Treatment burden:Financial impact and effort required by patients to receive care (e.g., travel, number of office visits, and duration of therapy) were key factors in patient decision-making. “Part of my quality of life went down because I had to fight with my insurance company consistently, and we pay a lot of money.” - Participant 11 “Really explain the time options and calendarize the treatment and be more specific about the amount of time that you're going to spend at the hospital and the process.” - Participant 20 5) Representation: Minority participants raised concerns about not knowing if the available treatment data pertained to them. “[My end-goal would be] having an understanding of how the treatment is going to be for minority people. Many times the treatments are tested, they are not tested for minorities.” - Participant 21 Conclusions: The patient perspective is critical for treatment decision-making and education. People living with FL expressed a desire for a holistic and individualized approach to treatment decision-making that incorporated their lifestyle, minimized side effects, and limited overall treatment burden. These focus groups identified emerging themes that warrant further investigation for survivors with FL.

Introduction: Autoimmunity in Rosai-Dorfman disease (RDD) has been reported in several case reports and small case series. The recent consensus RDD guidelines even classify “immune-related RDD” as a distinct entity, but little is known about the prevalence and patterns of autoimmune conditions in this rare disease. We conducted this study to evaluate a large cohort of patients with RDD for concomitant autoimmunity. Methods: We conducted a retrospective review of cases diagnosed with RDD from five referral centers globally. Data pertaining to autoimmunity were captured in terms of serology and a clinical diagnosis of autoimmune disease (AID) and compared to previously reported prevalence of AID and autoimmunity in the general population and in patients with other lymphomas. Results: We included 157 patients diagnosed with RDD from 2003-2023. Median age at the time of RDD diagnosis was 48 years, IQR 35.5-60. This included 103 females (65.6%) and 54 male (34.4%). Racial distribution included 54 Black (34.4%), 52 White (33.1%), 40 Asian (25.5%), 7 Middle Eastern (4.5%) and 4 other (2.5%). 83 patients had multi-systemic disease (52.8%) and 74 had single organ involvement (47.2%). Most common organs involved were skin/subcutaneous tissue (78, 49.7%), lymph nodes (63, 40.1%), bone (54, 34.2%). Tissue next generation sequencing data was available for 100 patients (63.7 %) and showed KRAS mutation (19, 19 %), MAP2K/MEK (13, 13%), other mutations (27, 27 %), and no mutations (41, 41%). Mean ESR at diagnosis of RDD was 28.42 mm/Hr and mean CRP was 19.5 mg/L. In our cohort, 28 patients (17.8%) were diagnosed with an AID. 19 (67.8%) were diagnosed with the AID prior to the diagnosis of RDD. Most common AID was systemic lupus erythematosus (6, 21.4%), rheumatoid arthritis (5, 17.8%), autoimmune hemolytic anemia (3, 10.7%), polymyalgia rheumatica (2, 7.1%). AID was more common in female vs male (64.3% vs 35.7%, p 0.8) and were more commonly seen in patients with multisystem compared to single organ RDD (60.7% vs 39.3%, p 0.3). Mean ESR and CRP at the time of RDD diagnosis in patients with AID were 40.63 mm/Hr and 37.04 mg/L respectively. Autoimmune antibodies were tested in 90 patients (57.3%), of which 43 (47.8%) were positive for atleast one autoantibody which included 15 patients (16.7%) with AID and a positive autoantibody and 6 (6.6%) with AID and negative antibodies (p 0.01). Most common antibodies were ANA (29/83, 34.9%), 42.3% with a titer higher than 1:160. Other antibodies include RF (10/60, 16.67%), anti-neutrophilic cytoplasmic antibody (3/19, 15.8%), double stranded DNA (6/56, 10.7%). Positive Antibodies were more common in female compared to male patients (72% vs 23%, p 0.04) and in patients from China compared to North America (45.7% vs 22.6%, p 0.007). Autoantibody positivity was common in multi-system vs single organ RDD (53.5% vs 46.5%, p 0.9). Mean ESR and CRP in this group of patients were 34.54 mm/Hr and 23.93 mg/L respectively. Median duration of follow up for our cohort was 32 months (IQR 14-65). Five-year survival was 93.4%. There were a total 8 deaths reported in the cohort, none of which were in patients with underlying AID. In a multivariable analysis, AID was associated with race (odds ratio [OR] for Middle Eastern compared with Chinese, OR 7, p=0.02) but other factors like organ involvement, mutational status, sex and age at diagnosis were not significant. Conclusions: Our study reveals a high prevalence of autoimmunity in RDD, both in terms of AID (17.8 %) and positive autoantibodies (47.8 %), which is much higher than the general population rates of approximately 3% and 16% respectively, and higher than patients with non-Hodgkin lymphoma, 7.6% and 39%, respectively. There was a trend toward association of AID with multisystem RDD and among individuals from North America and Middle East compared to China, although auto-antibody positivity was more common in Chinese patients. Mean ESR and CRP at the time of diagnosis of RDD was higher in the patients who had AID. We did not find any statistically significant association between AID and autoantibody positivity with the underlying driver mutation. Nearly half of the patients with RDD who also had AID did not have a positive autoantibody, thereby implying the need of clinical evaluation for rheumatological symptoms rather than empiric serological testing. Overall, this study also highlights the need to explore the biological link between RDD and autoimmunity.

Introduction: Light chain multiple myeloma (LCMM) is a distinct subtype of multiple myeloma (MM) characterized by the exclusive production of immunoglobulin light chains, unlike the common form of MM that produces the complete immunoglobulin. There is a paucity of literature on the specific tumor cell alterations leading to light chain-only disease as opposed to the typical presentation in MM. Additionally, data on treatment response and outcomes in this subgroup of patients is sparse. This study explores the differences in baseline characteristics, including cytogenetic abnormalities and treatment response between LCMM and multiple myeloma with heavy chain involvement. Materials and Methods: We reviewed patient charts to obtain clinical and laboratory information for individuals diagnosed with LCMM and those with heavy chain MM (comparison cohort) from 2004 to 2022. Patients were matched for age, sex, and year of diagnosis. Data collected included treatment assessment, overall survival, and progression-free survival (PFS). Associations between outcomes and categorical variables were analyzed using the chi-square test, while the Mann-Whitney U test was employed to compare medians. Progression-free survival following initiation of initial therapy and overall survival were assessed using Kaplan-Meier analysis. The Mayo Clinic Institutional Review Board (IRB) approved the study. Results: We identified 848 patients, representing 17.1% of newly diagnosed MM cases. The median age of the LCMM cohort was 63 years (range 16-92), with a female-to-male ratio of 1:5. The LCMM cohort had higher levels of lactate dehydrogenase (LDH), beta-2 microglobulin (p<0.0001), higher baseline creatinine (p<0.0001) and calcium (p<0.0001). The two cohorts had no significant difference in the International Staging System (ISS) or revised ISS (R2-ISS). Additionally, hemoglobin (Hb) and white blood cell count at presentation were higher in the LCMM cohort. Chromosome 1 abnormalities were lower in the LCMM cohort: 1q gain (OR-0.7; 95% CI: 0.6-0.9) and 1p deletion (OR-0.7; 95% CI: 0.6-0.9, p=0.02). Likewise, the frequencies of trisomies and hyperdiploidy were lower in the LCMM cohort, with odds ratios of 0.32 (p=0.012) and 0.37 (p<0.001), respectively. The frequencies of translocations t(4;14) (OR-0.35, p<0.001) and t(14;16) (OR-0.6, p=0.03) were lower in LCMM compared to heavy chain MM. In contrast, the frequencies of t(11;14) (OR-3.4) and t(6;14) (OR-4.9) and deletion of 13q(OR-1.3) was higher in the LCMM cohort. There was no significant difference in the occurrence of del(17p)/TP53 abnormalities. The median PFS after the first regimen was shorter in the LCMM cohort (23 months vs. 27 months, p=0.03), and this difference remained significant after adjusting for baseline adverse prognostic indices and treatment regimen. Median PFS in LCMM patients with monoclonal antibody (Mab) as part of their treatment was 37 months vs. 23 months (Proteasome Inhibitor or immunomodulator-based regimen without Mab), though this difference is not statistically significant p=0.87. No significant difference was found in overall survival between the two groups. Conclusion: This study highlights unique features of light chain multiple myeloma, including increased frequencies of specific cytogenetic abnormalities. Further evaluation of observed differences in cytogenetic abnormalities may enhance our understanding of LCMM and potentially guide baseline treatment choices to improve outcome.

Background: Proven salvage therapies for pts with triple-class refractory MM who progress on BCMA-targeted therapies are lacking.Fc receptor-homolog 5 (FcRH5) is a type I membrane protein that is expressed exclusively in the B-cell lineage. Cevostamab is a FcRH5xCD3 BsAb that facilitates T cell-mediated killing of MM cells. In an initial Phase I study (GO39775), cevostamab monotherapy was clinically active and had manageable toxicity in pts with heavily pretreated relapsed/refractory MM (Trudel et al. ASH 2021). In Cohort A1 of the subsequent Phase I/II CAMMA 2 study (CO43476; NCT05535244), cevostamab was highly active and had manageable safety at the 160mg target-dose (TD) level in pts with triple-class refractory MM who had received a prior BCMA-targeted antibody-drug conjugate (ADC; overall response rate [ORR]: 60%, 6/10 pts) or chimeric antigen receptor T-cell (CAR-T) therapy (ORR: 73%, 8/11 pts) but had not received a prior BCMA-targeted BsAb (Kumar et al. EHA 2024). We present initial results from Cohort A2, which enrolled pts with triple-class refractory MM who had received prior BCMA-targeted therapies, including ≥1 BCMA-targeted BsAb. An exploratory analysis of baseline patient and tumor-related factors is also presented. Methods: Cevostamab was initiated with step dosing (Cycle [C] 1 Day [D] 1: 0.3mg; C1D2, D3, or D4 depending on the emergence of cytokine release syndrome [CRS] after the initial administration: 3.3mg) and continued at the 160mg TD on C1D8 and on D1 of each subsequent 21-day cycle until disease progression (PD) or unacceptable toxicity. Cytokine, tumor antigen, T-cell function/activation, and inhibitory immune checkpoint expression were assessed in blood and tumor samples collected at baseline and during treatment. Results: As of February 23, 2024, 21 pts (median age: 64 years, range: 46-84) had been enrolled into Cohort A2. Seven pts (33%) had extramedullary disease and 5/12 pts (42%) with a conclusive assay result had high-risk cytogenetics (t(4;14), t(14;16), or del(17p)). All pts were heavily pretreated (median prior lines of therapy: 8, range: 5-14); 62% had received ≥2 prior BCMA-targeted therapies (median time since last: 122 days, range: 68-558) and 33% had received ≥2 prior BsAbs (median time since last: 139 days, range: 68-782). Most pts (86%) were refractory to their last line of therapy; 62% were penta-drug refractory. Median follow-up was 173 days (range: 20-360). Grade (Gr) 3-4 adverse events (AEs) occurred in 71% of pts (15/21). Gr 3-4 AEs in >3 pts were neutropenia, anemia, thrombocytopenia (38% each), and infections (29%). CRS occurred in 76% of pts (16/21) and was mainly Gr 1 (43%) or Gr 2 (29%); 1 patient had Gr 3 CRS. One treatment-related Gr 5 (fatal) AE of pneumonia was reported in the context of PD. No treatment-related AEs leading to cevostamab discontinuation occurred. Objective responses (partial response [PR] or better) were observed in 2/21 pts (ORR: 10%). Both pts achieved a very good PR and had ongoing responses at cut-off. Stable disease was observed in 10 pts (48%). Pts in the prior BsAb group had received more prior lines of therapy than those in the prior ADC and CAR-T groups (median 8 vs 5 and 6, respectively) and more prior BCMA-targeted therapies (median 2 vs 1 and 1). The percentage of pts with low levels (<4.5 ng/mL) of soluble BCMA in plasma was also higher in the prior BsAb group (47% vs 0% and 18%). At baseline, inhibitory immune checkpoint expression across T-cell subsets was more common in the prior BsAb group. Notably, the median frequency of PD1+CD8+Tnaive and TIGIT+CD8+Tnaive cells in blood was higher in the prior BsAb group (21% and 29%, respectively) than in the prior ADC (3% and 6%) and CAR-T groups (4% each). Peak median IL-6 and IFN-γ levels were delayed until the first TD in the prior BsAb group, suggesting a different pharmacodynamic profile. Conclusions: Cevostamab has manageable safety in pts with triple-class refractory MM who have received prior BCMA-targeted therapies, including ≥1 BCMA-targeted BsAb. Clinical responses were less frequent in the prior BsAb group than in the prior ADC and CAR-T groups, which could be explained by the higher number of prior lines of therapy and T-cell exhaustion due to multiple prior exposures to BsAbs. Notably, the high frequency of CD8+ T-cell subsets expressing inhibitory immune checkpoints in the prior BsAb group suggests a level of T-cell dysfunction that could prevent effective T-cell activation.

Background The American Society of Clinical Oncology (ASCO) launched the Diversity in Oncology initiative in 2017 to address the need for increased minority representation in the hematology-oncology workforce. A recent series of reports, titled “State of the Oncology Workforce in America,” published in JCO Oncology Practice in 2021 and 2022, focused on this issue. Notably, these reports did not include any data regarding the representation of Asian minorities in the field. Therefore, our objective was to assess the proportion of Asian professionals within the hematology-oncology workforce, encompassing both practitioners and trainees. Methods We conducted a comprehensive search for publicly available data regarding Asian representation among US hematology-oncology practitioners and trainees in both adult and pediatric fields. Our primary data sources included the 2020 US Census, the Association of American Medical Colleges, the Accreditation Council for Graduate Medical Education, and various professional societies. We defined practitioners to include hematologist-oncologists, gynecologic oncologists, radiation oncologists, surgical oncologists, hematopathologists, hematology-oncology nurse practitioners, hematology-oncology physician assistants, and nurses specializing in hematology-oncology. Trainees encompassed fellows and residents. Additionally, we gathered comparable data on the US population, medical students, adult internal medicine residents, gynecology residents, pediatric residents, pathology residents, surgery residents, nurses, nurse practitioners, and physician assistants. To provide a comprehensive overview of the hematology-oncology workforce, we utilized data from 2020 to 2022, and whenever possible, we collected longitudinal data on trainees over the years. Results As of 2020, Asians represented 6.2% of the US population. Among hematology-oncology physician practitioners, the percentage of Asian individuals ranges from 14.7% to 32.1%, including 32.1% of adult hematologist-oncologists, 20.4% of pediatric hematologist-oncologists, 25.9% of radiation oncologists, 14.7% of gynecologic oncologists, and 7.0% of hematology-oncology physician assistants. In the realm of physician trainees, Asian representation is between 17.9% and 35.3%, with 35.3% of adult hematology-oncology fellows, 20.0% of pediatric hematology-oncology fellows, 26.4% of radiation oncology residents, and 17.9% of gynecologic oncology fellows. Additionally, the proportion of Asian residents from which hematology-oncology fellows are drawn ranges from 14.9% to 35.9%. Specifically, 35.9% of internal medicine residents, 22.0% of pediatric residents, 14.9% of gynecology residents, 26.6% of pathology residents, and 19.2% of surgical residents are Asian. Furthermore, 26.7% of medical students identify as Asian. Notably, the proportions of Asian hematology-oncology trainees and medical students have remained relatively stable from 2005 to 2022. Data on hematopathologists, surgical oncologists, and non-physician practitioners are limited, although Asian representation among hematology-oncology physician assistants is 7.0% and among nurses is 7.2%. Conclusions Asians comprise a large segment of the hematology-oncology workforce in the US. While only 1 in 20 people in the US are Asians, between 1 in 3 and 1 in 5 hematology-oncology physician practitioners and trainees, are Asians. Data are limited for non-physician practitioners. Asian minority representation should be highlighted and considered as an example of success in diversity in hematology-oncology workforce. This framework should be embraced moving forward to continue advancing minority representation throughout the field of hematology-oncology.

Introduction MYD88 L265P mutations (MUT) are found in 90% of patients with Waldenstrom macroglobulinemia (WM) and lead to the activation of pro-survival signaling. Limited literature has demonstrated that patients with MYD88 wild-type (WT) WM have poorer responses to conventional therapies and a higher likelihood of histological transformation. Increasingly the role of non-coding genomics in lymphomagenesis has demonstrated importance and currently, the epigenetic landscape of MYD88 WT WM remains underexplored. This study utilized a multi-omics approach to assess DNA methylation in MYD88 WT WM compared to MYD88 MUT patients and controls. Methods Bone marrow samples were prospectively collected from 20 subjects [3 MYD88 WT/CXCR4 WT WM, 12 MYD88 MUT WM and 5 normal controls] and positive selection for CD19+ and/or CD138+ B cells was performed. The analysis focused on the comparison between MYD88 WT WM to normal controls and MYD88-WT to MUT WM. Genome-wide DNA methylation analysis was performed, and CpG methylation ratios were segmented into 200-bp regions. Differentially methylated regions (DMRs) were determined using a Q-value <0.05 and absolute methylation difference ≥10%. Next, RNA-seq data was interrogated and differentially expressed genes (log2fold change>0.5 or <-0.5, false discovery rate<0.05) with corresponding promoter hypo- or hypermethylation were assessed. Ingenuity Pathway Analysis was used to determine potentially epigenetically regulated pathways using a corrected p<0.05. Results Comparing MYD88 WT WM samples to controls, a statistically greater number of hypermethylated DMRs were observed across genomic regions (hyper- vs hypomethylated): promoter (29129 vs 6300), 3'untranslated region (UTR) (2068 vs 1551), 5'UTR (10169 vs 735), intron (30344 vs 24511), exon (2224 vs 6855), CpG island (30372 vs 1240) and CpG shore (14477 vs 5872) (all p<0.001). Next, mRNA analysis demonstrated that 214 genes were differentially up-/downregulated with concordant promoter hypo-/hypermethylation. On the assessment of promoter-methylation-based pathways, multiple pathways involved in cell signaling, proliferation, gene regulation, cytokine and immune signaling and metabolism were found to be deregulated. Most pathways were found to be negatively enriched in MYD88 WT patients compared to controls including several members of interleukin (IL) signaling (IL-2, IL-3, IL,7) and regulators of cell proliferation and signaling including mTOR, PI3K/AKT, and p53. Positive enrichment of the PTEN, FGFR3 and ERK/MAPK pathways were observed. Underlying multiple pathways was promoter hypermethylation with corresponding mRNA downregulation of AKT3 and PIK3CA. Furthermore, promoter hypomethylation with transcript upregulation of PTEN was observed. Next, in comparison of MYD88 WT to MUT samples, a statistically greater number of hypermethylated DMRs were observed across genomic regions (hyper- vs hypomethylated): promoter (24829 vs 2544), 3'UTR (3534 vs 378), 5'UTR (6111 vs 605), intron (52292 vs 5360), exon (21066 vs 2187), CpG island (18334 vs 1551) and CpG shore (16351 vs 1957) (all p<0.001). Assessing mRNA expression, 354 genes were up-/downregulated with concordant promoter hypo-/hypermethylation. Pathway analysis revealed positive enrichment of the mitotic G1 phase to G1/S transition pathway with upregulation of the CDK4, LYN, and PSMA6 transcripts in MYD88 WT compared to MUT samples. Further, negative enrichment of cell signaling regulators including the RHO GTPase family, IL pathways (IL-4, IL-8, IL-13, IL-17) and integrin signaling were found in MYD88 WT compared to MUT samples. Underlying multiple pathways were downregulation with promoter hypermethylation of BCL2, an important regulator of apoptosis. Conclusion Genome-wide methylation analysis of MYD88 WT WM revealed a unique DNA methylation profile, with potential epigenetic alteration of key oncogenic transcripts and pathways. The negative enrichment of cell signaling and cytokine/inflammatory pathways in MYD88 WT samples compared to controls and MYD88 MUT WM suggests an epigenetic mechanism for immune evasion and potentially underlies the reduced response to conventional WM-directed therapies. Overall, this study reveals that MYD88 WT WM is epigenetically distinct from MYD88 MUT WM and regulators such as methylation may underlie the unique clinical and phenotypic properties observed.