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Background: The COVID-19 pandemic had an outsized impact on individuals with immune compromise, such as multiple myeloma, leading to increased rates of severe COVID, hospitalization, and death in these groups. The pandemic also demonstrated the need for rapid and efficient evidence generation to address rapidly changing medical needs and accelerated the use of innovative trial designs to accomplish this goal. Methods: We designed and established a prospective, decentralized study within a site-based provider network, COVID-19 OutcomeS in Myeloma and the Impact of VaCcines (COSMIC), for patients with multiple myeloma at ASH Research Collaborative sites to monitor outcomes related to COVID-19 infection and vaccination. The direct-to-patient approach was accomplished using a study application accessed with a QR code provided to patients during usual clinical care. All study activities occurred within the patient portal at Baseline, Day 30, and Day 180, minimizing burden on site personnel and staff. Study activities included eligibility confirmation, consenting, electronic health record (EHR) data permissions, and patient-reported outcome (PRO) surveys. PRO data (EORTC QLQ-C30, EORTC QLQ MY-20) were made available to clinicians through the portal to visualize results from their patients. Patients shared if they received a COVID-19 vaccination or booster and if they had a COVID-19 infection. Patients with a history of COVID-19 infection included method of confirmation and if hospitalization was required. Patients were provided compensation for participation. Automated text and email messages were sent at three separate intervals: 24 hours, Day 8, and Day 15 for participants who initiated but did not complete study activities. A personal email reminder per participant was sent for those whose second study visit window was approaching. ASH Research Collaborative clinicians met regularly to share best practices related to enrollment and study conduct, thereby creating an innovative evidence generation learning community. We studied the feasibility of data collection in a decentralized format by focusing on the number of participants who interacted with the system, those who consented, and those who completed baseline PRO assessments. Results: The COSMIC study rapidly accrued and consented 200 patients from eight participating ASH Research Collaborative sites over four months (1/22/2024 through 5/17/2024): 69% self-reported as non-Hispanic White (NHW). Of enrolled participants, 57.5% opted to permission sharing of their EHR data, which included disease and treatment-related clinical data, laboratory results, pathology reports, and imaging reports. A total of 196 patients (98%) provided demographic and COVID-related disease and vaccine data at baseline; nearly all of these patients (n=195) provided baseline PRO data, and 150 patients provided further information at Day 30 at the time of this analysis. Those who did not provide Day 30 data were not significantly different from those who did in terms of age (median: 68 [no Day 30 data] vs. 67 [Day 30 data] years; p=0.44), sex (41% [no Day 30 data] vs. 47% [Day 30 data] Female; p=0.47), or race (65% [no Day 30 data] vs. 71% [Day 30 data] NHW; p=0.60). A higher proportion of Hispanic patients were retained at Day 30 (13/15=87%) vs. 78% of non-Hispanic patients or those who declined reporting ethnicity (2/7=29%; p=0.007). COVID-19 vaccination data were submitted by 196 patients, 186 of whom had ever received a COVID-19 vaccination. Data on number, type, brand, and dates for these vaccinations were provided. Conclusions: The COSMIC study conducted by the ASH Research Collaborative was able to rapidly accrue a diverse cohort of patients using a decentralized workflow within a site-based provider network, with high consent and compliance rates. This platform, and the innovative evidence generation learning community of ASH Research Collaborative investigators and patients, sets a precedent to address a variety of real-world questions related to disease management, infections, vaccinations, and PROs in this population of patients with multiple myeloma.

Background: Data from the ASH Research Collaborative COVID-19 Registry for Hematology demonstrated that patients with multiple myeloma and other immune compromise had elevated risk for severe complications from COVID-19 infection. To address current evidence gaps and to demonstrate proof of concept for a pandemic preparedness and response network, the ASH Research Collaborative Multiple Myeloma Program developed a prospective, decentralized study within a site-based provider network to investigate COVID-19 infections, vaccinations, and quality of life in patients with multiple myeloma. Methods: We designed and established the COVID-19 OutcomeS in Myeloma and the Impact of VacCines (COSMIC) to study COVID-19 in patients with multiple myeloma at ASH Research Collaborative network sites. A study application was accessed with a QR code and shared with patients during usual clinical care. Patients provided consent, optionally gave permission for electronic health record data collection, and completed patient-reported outcomes (EORTC QLQ-C30 and MY20) at baseline, Day 30, and Day 180 through the study portal. Clinicians at participating sites facilitated study enrollment and shared best practices monthly to accelerate study execution. Study objectives related to feasibility of data collection in a decentralized format are reported in a separate abstract. Here, we report interim results related to SARS-CoV-2 vaccination history, COVID-19 infection, and how these relate to patient reported outcomes and clinical outcomes in enrolled participants. Results: The COSMIC study rapidly accrued and consented 200 patients from eight participating ASH Research Collaborative sites over four months (1/22/2024 through 5/17/2024). Consented participants' ages ranged from 29 to 93 years, with median of 67 years; 46% were female, 69% were non-Hispanic White (NHW), 17% were non-Hispanic Black (NHB), and 8% were Hispanic/Latino. Of the 196 patients who reported COVID-19 data, 111 (57%) reported at baseline that they had a history of COVID-19 infection, with 12 having required hospitalization for this (12/111=11%). Overall, 95% (186/196) reported a history of COVID-19 vaccination, where the median number of vaccinations was 4 (range: 1 to 6); 44 patients (23%) expressed willingness to discuss getting a yearly booster vaccine with their provider. At 1-month follow-up, there were 3 additional patients who reported a COVID-19 infection and 18 patients who received an additional COVID-19 vaccination. The baseline EORTC QLQ-C30 median Global Health Status/QOL score was 66.7 (mean=64.4, range: 8.3 - 100, n=196). This overall global QOL score was not significantly different between those who did vs. did not have a history of COVID-19 infection (mean [SD]: 63.7 [19.3] vs. 65.8 [17.6]; p=0.57). In analyses adjusted for age, biological sex, and race/ethnicity group, history of COVID-19 infection was not associated with HRQOL (odds ratio=0.93, 95% CI: 0.78 - 1.10; p=0.38). Data collection is ongoing and final study results will be reported at a later date. Conclusion: COSMIC is a prospective, decentralized study within a site-based provider network conducted by the ASH Research Collaborative Multiple Myeloma Program that demonstrates the feasibility of using an innovative evidence generation strategy to drive rapid accrual of patients to address a rapidly evolving area of need. The COSMIC study also provides proof of concept that a real-world evidence generation network can play an important role in national pandemic preparedness and response. The COSMIC experience reinforces the ability to accrue diverse patient populations representing the demographic of myeloma patients in the US.

Introduction: MPAL is a rare and heterogenous subtype of acute leukemia characterized by a single blast population with phenotypic expression of both myeloid and lymphoid lineages (biphenotypic) or multiple co-existing lineages of blasts that satisfy criteria for both acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). MPAL presents both a diagnostic and therapeutic challenge given its rarity and resistance to traditional therapies. Data suggest ALL-directed or hybrid therapies are most effective at inducing durable remissions as a bridge to allogeneic stem cell transplantation (Allo-SCT; Lazzarotto 2023, Rasekh 2021); however, many are single-institution with limited sample sizes. Methods: A retrospective analysis at 7 US academic centers was performed. Adult patients (pts) with a confirmed diagnosis of MPAL between 2003-2023 were included. Comparisons of categorical and continuous variables utilized the Fisher exact test and Wilcoxon rank-sum or Kruskal-Wallis test as appropriate. Time-to-event outcomes were calculated using the Kaplan-Meier method and compared using log-rank test. Results: A total of 79 pts with MPAL were included in this study. Median age at diagnosis was 61 years (range, 18-89); 52% were ≥ 60 years. Majority of pts were male (60%), non-Hispanic white (64%), and had an ECOG ≤ 1 (83%). Of the 50 pts with baseline CSF analysis, 5 (10%) had CNS disease. Phenotypically, the predominant blast population was biphenotypic in 68%, myeloid in 17%, and lymphoid in 15% of cases. KMT2A-rearrangement and BCR::ABL1 translocation constituted 4% and 14% of cases, respectively, and 30% of pts had complex cytogenetics. Most common mutations at baseline included RUNX1 (33%), DNMT3A (30%), FLT3-ITD (26%), TET2 (19%), WT1 (19%), NRAS (18%), TP53 (17%), and ASXL1 (14%) mutations. Of the 79 pts, 61 (77%) received intensive chemotherapy (IC), 12 (15%) received HMA-based regimens, 4 (5%) received other non-intensive regimens, and 2 (3%) transitioned to hospice prior to therapy. Among those receiving IC, 37 (61%) received ALL-directed therapies, 16 (26%) AML-directed, and 8 (13%) received hybrid regimens which included FLAG-VIPR (6/8), 7+3+vincristine (1/8), and cladrabine/low-dose cytarabine/vincristine/dexamethasone (1/8). Therapies were phenotype-discordant in 4/61 pts receiving IC; 3 myeloblast-predominant MPAL pts received ALL-directed therapy and one lymphoid-predominant pt received AML-directed therapy. Among 54 pts with predominant biphenotypic blasts, 52% received ALL-directed regimens. Of the 11 pts with BCR::ABL1 translocation, 8 (73%) received dasatinib, 2 (18%) ponatinib, and 1 (9%) received both. Only 30% of pts with FLT3-ITD mutated MPAL (5/17) received a FLT3 inhibitor. Overall, 56% of pts achieved complete remission (CR) or CR with incomplete count recovery (CRi), with a median duration of response of 16.7 months (IQR: 8.1-46.1). The rates of CR/CRi were 39%, 56%, and 75% for myeloid, biphenotypic, and lymphoid MPAL, respectively. All pts with CNS disease (5/5) cleared after induction. Thirty-seven percent of pts proceeded with Allo-SCT in first remission (23% of myeloid pts, 58% lymphoid, 35% biphenotypic). Thirty-two percent of responders (CR/CRi; 14/44) relapsed with a median time to relapse of 9.4 months (range, 0.5-42). Median overall survival (OS) for the entire cohort was 51 months (95% CI: 15-89). The 2-year OS rate was higher in pts with lymphoid-predominant phenotype (83%) compared to biphenotypic (55%) or myeloid-predominant phenotype (38%; p=0.16). Median OS was significantly longer in transplant versus non-SCT recipients (121 vs 14 months) with a 1-year OS rate of 97% vs. 59% (p<0.0001), respectively. Among pts who achieved CR/CRi, median OS significantly longer in transplant versus non-SCT recipients (121 vs 55 months, p=0.031), with a 2-year OS rate of 91% vs 75%. Conclusions In this large multi-center study, there were differences in survival based on predominant blast phenotype, with improved OS in lymphoid-predominant MPAL. Although most pts with biphenotypic-predominant MPAL received ALL-directed regimens, OS was worse in this subtype compared to lymphoid-predominant MPAL. There was significantly improved OS among Allo-SCT recipients underscoring the importance of Allo-SCT in this subtype of acute leukemia. Additional studies are needed to understand this rare and heterogenous disease.

Background: Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a severe thrombotic thrombocytopenia that predominantly occurs after adenoviral vector-based vaccines. VITT patients produce anti-platelet factor 4 (PF4) antibodies with restricted clonality (i.e., mono/oligoclonal) with lambda light chains. Long-term follow-up studies in VITT show a disconnect in the persistence of anti-PF4 antibodies, whereby ELISA-positive antibodies persist significantly longer than platelet-activating antibodies. The mechanistic basis of this is unclear and could be explained by a couple of hypotheses: (1) Epitope spreading where, with time, the specificity of platelet-activating anti-PF4 antibodies may “spread” to recognize only PF4 complexed to heparin vs. (2) Persistence of clonally restricted platelet-activating anti-PF4 antibodies which decrease in titers with time such that their levels are insufficient to crosslink platelet FcGRIIa and induce platelet activation. Methods: Acute, convalescent patient sera and affinity-purified anti-PF4 antibodies were evaluated in antigen-based, functional (platelet-activation-based), and mass spectrometry studies as previously described (Blood, 2022 Jul 7;140(1):73-77). The median time to last follow-up was 243 days after the acute episode (range: 114-664 days). Results: Follow-up samples were obtained from 6 VITT patients after Ad26.COV2.S vaccination. At last follow-up, anti-PF4 IgG antibodies reactive in PF4/polyanion ELISA were detected in the sera of 5/6 VITT patients. However, only one of these samples stimulated platelet activation in the PF4-dependent P-selectin expression assay (PEA; 199 days after acute presentation). Affinity-purified anti-PF4 antibodies were detected by ELISA in all follow-up samples and three of the six affinity-purified anti-PF4 antibody samples activated platelets in the PEA. Four of the six VITT patients demonstrated a monoclonal anti-PF4 antibody, while one each had a biclonal and triclonal profile. Five VITT patients produced IgG lambda light chain antibodies, while one produced an IgG kappa. All six VITT patients demonstrated synonymous anti-PF4 antibody profiles when comparing acute and follow-up antibody repertoires, without evidence of VITT patients producing new anti-PF4 antibodies after the acute episode. In all cases, levels of anti-PF4 antibodies were significantly lower in convalescent samples relative to acute samples. Given this data on the persistence of clonally-restricted VITT antibodies, samples from another VITT patient with thrombocytopenia (100-150,000/uL) persisting for more than three years were similarly evaluated. This patient, who experienced severe thrombosis after ChAdOx1 nCoV19 vaccination, demonstrated persistent ELISA and PEA positivity even three years after symptom onset but had not experienced breakthrough thrombosis while on anticoagulation therapy. Serum protein electrophoresis (SPEP) did not detect a monoclonal gammopathy. Anti-PF4 antibodies immuno-enriched from a sample obtained >2 years after acute presentation demonstrated a monoclonal profile. While non-availability of an acute sample for anti-PF4 antibody characterization precluded a firm determination of whether this “Long VITT” case represented a subset of monoclonal gammopathy of thrombotic significance (MGTS; Blood 2023 Apr 6;141(14):1772-1776; New Eng J Med 2024 Aug 8), the chronicity of thrombocytopenia, presence of a monoclonal anti-PF4 antibody and persistently positive anti-PF4 serology supports this diagnosis. Conclusions. Clonally-restricted VITT antibodies persist for months-years with no evidence for the production of novel anti-PF4 antibodies after the acute event. Decreased abundance of anti-PF4 antibodies leads to negative functional results with follow up samples. Some platelet-activating antibodies can persist for very long periods (>3 years) and mediate persistent thrombocytopenia, representing an SPEP-negative MGTS-like state. This study also demonstrates the first example of a VITT antibody with a kappa light chain. The requirement for anticoagulation in patients demonstrating ELISA-positive/functional test-negative results is not clear, but the persistence of mono/oligoclonal anti-PF4 antibodies raises the possibility for the upregulation of pathogenic antibody production in proinflammatory settings.

Introduction: Acute myeloid leukemia (AML) has been considered by many to be an oncologic emergency often leading to hospital admission for expeditious evaluation and treatment. Previous studies reported that time from diagnosis to treatment (TDT) does not impact outcomes (Sekeres, Blood, 2009), (Bertoli, Blood, 2013), (Rollig, Blood, 2020), however these analyses were restricted to intensively treated and/or non-United States (US) patients (pts). We report on a multi-center, retrospective analysis of TDT in adults with newly diagnosed AML receiving Hypomethylating agent (HMA) + venetoclax (Ven) using real-world data from the COMMAND. Methods: Eight US academic medical centers with AML expertise performed a review of adult pts within their center treated with HMA+Ven for newly diagnosed AML. TDT was defined as days from diagnosis of AML to initiation of treatment with HMA+Ven. Cytoreduction with hydroxyurea or leukapheresis was included to control for the effects of severity of presentation on TDT. The primary outcome was impact of TDT on overall survival (OS) (defined as date of diagnosis to date of death). TDT was treated continuously for time-to-event analyses. Secondary outcomes included measurable residual disease (MRD) by flow cytometric analysis (sensitivity <0.1%), complete response (CR), complete response with incomplete count recovery (CRi), defined by European LeukemiaNet (ELN) 2022 Guidelines (Dohner, Blood,2022), and early mortality (death within 30 and 60 days of initiation of HMA+Ven). Pre-planned subgroup analyses included those based on disease biology (FLT3 ITD, IDH1/2, TP53 mutation, ELN 2022 risk), HMA used (azacitidine vs decitabine) and age (<75 vs ≥75 years). For those analyses where TDT was significant in univariable analysis (P=0.1), multivariable analysis was conducted controlling for the following: ECOG performance status (PS), age, receipt of cytoreduction, ELN 2022 risk, and presence of individual pathogenic variants detected on broad myeloid gene next generation sequencing panels used at each institution. All analyses were conducted by a central statistician using RStudio statistical package. Results: 488 pts were included in the analysis. Median age was 76 (interquartile range: 70-80) and the majority of pts had an ECOG PS of 0 or 1 (56%). Most pts (67.6%) had adverse risk with 9.4% and 18.6% of pts having favorable and intermediate risk disease by ELN 2022, respectfully. The most common mutations identified were TP53 (27.5%), IDH1/2 (19.3%), NPM1 (16.4%), DNMT3A (16.8%), ASXL1 (15.4%), and FLT3-ITD (13.7%). Twenty-eight percent of pts received cytoreduction prior to initiation of HMA+Ven. Azacitidine+Ven was the most common regimen utilized (53.9%). Median number of cycles of HMA+Ven was 3 (IQR: 1-6). MRD (-) CR, MRD (+) CR, and CRi was achieved in 21.5%, 10.5%, and 16.4% of pts after one cycle of HMA+Ven. Median OS for the cohort was 10.4 months (95% CI: 9.4-12.6). Median TDT for the cohort was 9 days (IQR: 5-17). In univariate Cox model, longer TDT was associated with improved OS (HR: 0.989, 95% CI: 0.981 to 0.998; p = 0.013). In multivariable analysis, longer TDT was still associated with improved OS (HR: 0.987; 95% CI: 0.973-0.999; p=0.049). TDT and presence of bZIP in-frame CEBPA mutations were the only factors associated with improved OS, while ECOG PS of 2 or 3-4, when compared to ECOG PS=0 (p=0.035 and 0.0002, respectively) and therapy-related AML (p=0.002), were associated with worse OS. Notably, ELN 2022 risk and IDH1/2 or NPM1 mutation status did not impact OS. Discussion: In this real-world, multi-center, US-based analysis of pts with newly diagnosed AML treated with HMA+Ven we show that longer TDT is associated with improved OS even when controlling for severity of presentation, ELN 2022 risk score, ECOG PS, and age. This finding is consistent with data in pts treated with 7+3. Similar to results published in an electronic medical record-based analysis out of Germany (Baden, Haemotologica, 2024) in pts treated with lower-intensity Ven regimens, our results show that pts with newly diagnosed AML eventually treated with HMA+Ven are best served with a complete appraisal of disease biology and treatment planning before initiation of induction therapy. Given the consistent negative impact of ECOG PS and the findings of our study, future consideration for potential patient optimization strategies to improve ECOG PS prior to therapy initiation are warranted.

Introduction. Platelet-activating anti-Platelet factor 4 (PF4) antibodies mediate a number of thrombotic thrombocytopenic syndromes, including heparin-induced thrombocytopenia (HIT), and more recently recognized conditions, vaccine-induced immune thrombotic thrombocytopenia (VITT), adenovirus-associated thrombotic thrombocytopenia, and monoclonal gammopathy of thrombotic significance (MGTS). In MGTS (Blood. 2023 Apr 6;141(14):1772-1776), a monoclonal IgG antibody to PF4 mediates a chronic prothrombotic state characterized by recurrent thrombosis. More recent evidence suggests that MGTS may present with negative results in HIT enzyme-linked immunosorbent assay (ELISA) and serotonin release assay (SRA), and positivity only in PF4-dependent functional assays such as the PF4-dependent P-selectin expression assay (PEA; submitted). The presence of MGUS in patients has long been associated with high risks of thrombotic disease (Blood. 2010 Jun 17;115(24):4991-8), but the mechanism by which they predispose to thrombosis has been relatively unexplored. In this study, we evaluated a cohort of MGUS patients who experience thrombosis for the presence of platelet-activating anti-PF4 antibodies. M ethods. An administrative database search was performed of Mayo Clinic records to identify patients who had a diagnosis of MGUS, and thrombosis. Research samples from 134 MGUS patients with IgG monoclonal protein and thrombosis were obtained from Mayo Clinic's dysproteinemia biobank and subjected to PF4 antigen-based and functional screening. Research studies were approved by the Institutional Review Board of Mayo Clinic. Results. Of the 134 patients, 17 (12.7%) activated platelets in the PEA (≥19%). To exclude non-specific activation (e.g. due to HLA antibodies), secondary PEA testing was performed to assess whether platelet activation was mediated by a HIT-like antibody (i.e., PF4- and IgG-dependent, and inhibitable with high concentrations of heparin). Four patients, hereafter referred to as patients 1-4, were identified as having a HIT-like antibody, as demonstrated by PF4-dependent platelet activation that could be inhibited with high concentrations of heparin (100 U/mL), and blockade of the platelet IgG receptor, FcγRIIa. Patients 1 and 2 had persistent, platelet-activating anti-PF4 antibodies based on PEA testing of multiple samples obtained several years apart. Patient 1 had a recurrent, multi-year history of deep venous thrombosis (DVT), while patient 2 had one DVT episode. Patient 3 demonstrated a HIT antibody-like profile in the PEA in two of three samples available for testing and had a history of thrombotic cerebrovascular accident (CVA). Patient 4 demonstrated a HIT-like platelet-activating antibody in only one of four samples tested, and consistent with this finding, had an MGUS identified on clinical testing at only one time point (“small” IgG lambda, not quantified), 3 months prior to the platelet-activating sample. This patient experienced multiple thrombotic events including DVTs, left atrial thrombus and embolic CVA, pulmonary embolism and acute limb ischemia. All patients tested negative in two FDA-approved antigen-based HIT assays tested (Immucor PF4 IgG and Zymutest HIA IgG), similar to a recent MGTS case (submitted). SRA was negative in both Patients 1 & 2, weakly positive in Patient 3 (33%, with high CV), and positive (72%) in Patient 4. Conclusions. Definitive diagnosis of patients with MGTS provides insight into a mechanism of “unexplained” thrombosis and may offer additional treatment pathways for these patients with recurrent thrombosis (New Eng J of Med, 2024 Aug 8). Serologic testing in two patients correlated strongly with observations of thrombosis, and the study confirmed recent findings that anti-PF4 antibodies may present with unusual serology that is neither HIT- nor VITT-like (with negative results in both ELISA and SRA). The incidence of confirmed/suspected MGTS was 3% (4/134) in this population of MGUS patients with thrombosis. Prospective studies are needed to confirm these observations.

Background: Acute promyelocytic leukemia (APL) is one of the most treatable leukemias in the current era, with cure rates upwards of 90%. Early mortality due to coagulopathies often seen at diagnosis is a major driver of adverse outcomes. Prompt initiation of all-trans retinoic acid (ATRA) is crucial for suspected APL, as it is known to reverse these coagulopathies. Chemotherapy-free protocols consisting of arsenic trioxide (ATO) and ATRA have become the standard of care for low-risk APL with high cure rates and reduced hematologic toxicities. For high-risk disease, there are multiple treatment options that have not been compared. Since APL is rare, there is a lack of real-world data for this disease. This retrospective review aimed to assess the outcomes of APL patients (pts) across multiple institutions and to examine the most common induction regimens, characteristics linked to early (30-day) mortality, and supportive care strategies. Methods: This retrospective study involved 9 institutions in the US and was conducted through the Consortium on Myeloid Malignancies and Neoplastic Diseases (COMMAND). Data included pts admitted from 8/5/2006 through 2/3/2024 with a confirmed diagnosis of APL. Each institution received a data-collection form and contributed data on APL pts from presentation to last follow-up. Key data categories included patient demographics, presenting laboratory and molecular data, treatment regimen, supportive care, and patient outcomes. Results: Data for 412 pts were identified with a median age of 51 (range 17-90) and 49% were female. Cardiovascular comorbidities were present in 44% of pts and 16% had a known pulmonary comorbidity. At presentation 109 (27%) had high risk-disease, defined as a white blood cell count (WBC) greater than 10 x 109/L. A FLT3 mutation was seen in 50% of tested pts, WT1 (22%), KRAS (3.6%), and NRAS (6.5%). The median WBC at presentation was 2 x 109/L (range: 0-166 x 109/L) and the median platelet count was 27 x 109/L (range: 2.0-315 109/L). Twenty-six percent presented with grade 2+ thrombosis, bleeding, or both. A higher percentage of pts with high-risk vs. low-risk disease presented with grade 2+ thrombosis, bleeding, or both (43% vs. 20%), DIC (60% vs. 36%), and mutated FLT3 (81% vs. 37%). The majority of pts received a chemotherapy-free induction regimen consisting of ATRA plus ATO. It was determined that 36 (8.7%) pts received induction with intermittent ATO plus ATRA (Burnett AK, Lancet Oncol 2015), 276 (67%) received daily ATO plus ATRA (Ravandi F, J Clin Oncol 2009 and Lo Coco, NEJM 2013), and 70 (17%) received a regimen inclusive of an anthracycline plus ATRA. Eleven pts did not start an induction regimen other than single-agent ATRA due to early death, while 19 had their regimen classified as “other” because they did not follow a conventional induction path. In total, 295/358 (82%) received ATRA within 24 hours of admission. At least 1 dose of gemtuzumab ozogamicin was given to 58 (14%) pts, of which 35 (60%) were considered high risk. The incidence of differentiation syndrome (DS) was 37% (n=154). Among the 243 pts who received steroid prophylaxis, 30% developed DS, compared to 52% of those who did not receive prophylaxis. Among the 360 pts with at least 1 available PCR result after starting induction, 94% achieved PCR-negativity. The 30-day mortality rate was 6.6%. On univariate analysis, presenting variables associated with a higher 30-day mortality include older age, diabetes, cardiovascular comorbidities, thrombosis or bleeding, DIC, eGFR < 60, elevated total bilirubin and D-dimer levels, and high-risk disease. The median overall survival (OS) of the cohort was not reached, and the 5- and 10-year OS was 88% (95% CI: 84-91%) and 79% (95% CI: 72-87%) respectively. The cumulative incidence of relapse at 3 years was 2.7% (95% CI: 1.4 - 5.1%), with no additional relapses observed. The incidence of CNS relapse at 3 years was 0.9% (95% CI: 0.3% - 2.8%), with 2 of the 4 pts classified as high-risk. Conclusion: This is the largest real-world evidence data collection in the US evaluating the outcome of pts with APL in the current era, inclusive of ATO as front-line induction. Outcomes for this disease remain extremely positive, with low 30-day mortality rates noted in this study along with durable OS rates and low incidence of relapse. Additional information on outcomes, safety, and supportive care will be presented at the meeting.

Background: Chromosomal rearrangements involving the KMT2A gene and mutations involving the nucleophosmin (NPM1) gene have been associated with response to menin inhibitors in multiple studies of acute myeloid leukemia (AML) patients characterized by these genetic alterations. Both alterations are more common in younger AML patients and those with NPM1 mutations historically perform better. However, the prevalence and outcomes of older (≥60 years) AML patients with these alterations who are treated with current therapies is less well understood. We present results from the Beat AML Master Trial (BAMT) that analyze the outcomes of this large, but less common subset of patients in an older AML population. Methods: Patients were consented and enrolled on this precision medicine-based Beat AML Master Trial (NCT03013998) from November 2016 to June 2024. Patients were included in this analysis if they harbor either the classic NPM1 mutation or a KMT2A rearrangement (over 10 different gene partners). Additionally, 2 patients with a NUP98 rearrangement were included with the KMT2A cohort as they are known to have similar biology in terms of menin dependence. These patients were treated with the following therapies: a sub-study specific targeted therapy for the dominant clone, venetoclax + hypomethylating agent (Ven/HMA), intensive chemotherapy (IC), alternative non-intensive therapy (NIT), or no therapy. Clinical/genetic characteristics and median overall survival (OS) were analyzed in each group separately. Overall survival (OS) was calculated from master consent and estimated using the Kaplan-Meier method. Results: Of 1096 AML patients enrolled on the BAMT, 246 patients had either an NPM1 (N=207, 18.9%) or KMT2A (N=39, 3.6%) genetic alteration. The baseline characteristics for the NPM1 cohort were median age 72 years (range: 60-92), 50% female, and ECOG performance status: 0-16%, 1-58%, 2-25% and 3-1%. Additional disease characteristics include treatment related AML at 11% and complex karyotype (≥3 abnormalities) at 3%. Median OS for the entire NPM1 cohort was 18.4 months (95% CI: 14.2-24.7). Patients were treated on a sub-study (35%), Ven/HMA (19%), IC (26%), NIT (8%) or no treatment (9%). Between treatment groups, median OS was 21 months (95% CI: 12.8-31.7) for those treated on a sub-study, 22 months (95% CI: 12.6-not reached (NR)) for Ven/HMA, 41.6 months (95% CI: 18.2-NR) for IC, and 6.3 months (95% CI: 1.3-23) for NIT, which was significantly different (p<0.0001). The baseline characteristics for the KMT2A cohort were median age 69 years (range: 60-88), 44% female, and ECOG performance status: 0-19%, 1-45%, 2-35% and 3-0%. Treatment related AML occurred in 23% of patients and complex karyotype in 31%. Median OS for the KMT2A cohort was 6.5 months (95% CI: 3.6-31.6). Patients were treated on a sub-study (38%), Ven/HMA (15%), IC (15%), NIT (15%), or no treatment (5%). Between treatment groups, median OS was 31.6 months (95% CI: 3.2-NR) for sub-study, 5.0 months (95% CI: 3.0-NR) for Ven/HMA, 12.7 months (95% CI: 4.9-NR) for IC, and 2.9 months (95% CI: 1.5-NR) for NIT, which was also significantly different (p<0.0001). Conclusions: In this cohort of older AML patients who possess NPM1 or KMT2A mutations, initial demographics and clinical characteristics upon presentation are as expected. Within each cohort and depending on the type of therapy received, there were interesting differences in survival. Median OS was the highest for the NPM1 cohort that received IC while the KMT2A cohort had the highest median OS when enrolled on a KMT2A targeted sub-study; a finding that supports precision-based medicine for this high-risk KMT2A group characterized by poor outcomes. As menin inhibitor combinations with induction chemotherapy or Ven/HMA move to the frontline setting, we anticipate seeing significant improvement in outcomes for AML patients in both of these genomic subsets. Further multivariable analysis will be performed to validate treatment effect on OS. Our analyses for these two cohorts also provide valuable outcome benchmarks for the design of future precision oncology studies that seek to improve survival in these subsets of older AML patients.

Background: Patients with immunocompromising conditions, including those affected by hematologic malignancies, have a disproportionately high burden of morbidity and mortality related to COVID-19 compared to individuals without such conditions.Clinical practice guidelines (CPGs) recommend the use of remdesivir, a broad-spectrum antiviral, for treatment of mild to severeCOVID-19 in immunocompetent patients not requiring invasive mechanical ventilation. While the CPGs issued by the World Health Organization (WHO, 2023), National Institutes of Health (NIH, 2023) and the Infectious Diseases Society of America (IDSA, 2022) also recommended the use of remdesivir in patients with immunocompromising conditions at high risk for severe disease, there was limited evidence available at the time the recommendations were communicated, more than two years after the start of the pandemic. The European Conference on Infections in Leukemia (ECIL, 2022) guidelines include remdesivir among the treatment options for mild to moderate COVID-19 patients with hematologic malignancies. The lack of evidence for treatment efficacy and safety in patients with immunocompromising conditions, a population underrepresented or excluded from clinical trials, was mentioned in CPGs as a knowledge gap and as need for further research. In this research, we summarize the evidence for remdesivir efficacy and safety for treatment of COVID-19 in hospitalized patients with hematologic malignancies accumulated since the start of the pandemic. Methods: We systematically searched MEDLINE, Embase and Cochrane Library databases from January 2019 through December 2023 for interventional and observational studies examining remdesivir efficacy and safety. Case reports and case studies were excluded. A dual-reviewer approach was used for screening and data extraction. Results: Of the 7,654 references retrieved through the implementation of the extensive search strategy 59 (0.8%) reporting on patients with hematologic malignancies, unspecified cancers, or immunodeficiencies were identified and reviewed in full text. Only eight unique studies (8 of 59) were conducted in patients with hematologic malignancies, of which two reported remdesivir use in a minority of participants (n<5) and were excluded from further analyses. The remaining six studies, of which four were peer-reviewed original articles, one was a letter to editor and the last was a conference abstract, used a retrospective cohort design and reported efficacy outcomes for a combined total of 1,579 individuals across the studies. Three of the six studies were conducted during the pre-Omicron variant era (November 2021) while the remaining three started data collection in December 2021. There were four studies reporting number of deaths or the mortality rate, while a fifth study based on medical chart reviews of 313 patients in Israel found a significantly reduced risk of mortality among remdesivir recipients compared to patients not receiving remdesivir (OR: 0.297; 95% CI: 0.105, 0.834). In addition, a study including 466 patients from the Spanish Hematopoietic Stem Cell Transplantation and Cell Therapy Registry reported mortality among remdesivir treated group related to baseline disease progression, use of corticosteroids for COVID-19 therapy and the presence of coinfections while B-cell malignancy as underlying disease, severe COVID-19, late antiviral initiation (≥5 days after first positive PCR) and longer treatment duration (≥5 days) were factors significantly associated with prolonged viral shedding. The same Spanish study reported safety outcomes indicating that adverse events of grade 3 or above were rare, occurring in 0.5% of remdesivir treated patients. Conclusion: Despite the call for research to fill the knowledge gap signaled by the CPGs, our comprehensive systematic literature review identified only a few publications conducted since the start of the pandemic in patients with hematological malignancies. In the current endemic era, these patients are among the most at risk for severe outcomes and COVID-19 related hospitalizations. While the limited evidence suggests that remdesivir use can reduce mortality in patients with hematologic malignancies, additional research will be instrumental to inform development and updating of evidence-based recommendations to support and guide clinical management of oncology patients.

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.