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Abstract Background: Minimal residual disease (MRD) is a critical prognostic and therapeutic response marker in multiple myeloma (MM). Two main technologies are used for MRD assessment in bone marrow: next-generation flow cytometry (NGF) and next-generation sequencing (NGS), from clonoSEQ. While both methods are FDA-cleared and clinically relevant, they differ in sensitivity, sample handling requirements, and technical differences. Comparative performance in real-world matched samples is understudied. Here we compared the detection rates and concordance between MRD by NGF (flow cytometry) and NGS-based clonoSEQ, using paired bone marrow aspirates collected at the same clinical timepoint. Methods We identified 246 paired bone marrow samples from MM patients, which were evaluated by both flow cytometry (Euroflow, typically sensitivity of 10-5) and clonoSEQ (sensitivity of up to 10-6) on the same collection date.MRD-negativity for clonoSEQ was defined as no detectable clones and below the assay's level of detection (LoD). Continuous variables (clonoSEQ and flow CPS) were analyzed using the Mann-Whitney U test. Categorical variables were assessed using chi-square tests with Yates continuity correction for 2x2. A cox proportional hazards model was used to evaluate the association between overall survival and cytogenetic abnormalities, MRD status, and other clinical covariates including age, sex, treatment type, and disease setting (newly diagnosed, relapsed/refractory). A p-value < 0.05 was considered significant. Results Out of 246 paired bone marrow samples, we identified 173 concordant samples, out of which 26 were concordant positive (clonoSEQ+/NGF+), 147 were concordant negative (clonoSEQ-/NGF-), and 73 were discordant (clonoSEQ+/NGF-). clonoSEQ detected MRD in all cases missed by NGF, including some with relatively high tumor burden, reflecting its higher sensitivity. Among discordant samples, 45 (61.6%) were following treatment of newly diagnosed MM (NDMM) and 28 (38.4%) treatment of relapsed/refractory (RRMM). Among the MRD-positive samples, the concordant group (n=26) showed a mean clonoSEQ count of 11923.5 cells per million (CPM) and a mean NGF CPM of 305.5 (p<0.01). In contrast, the 73 discordant samples had a lower mean clonoSEQ CPM of 156.1. For the 147 MRD-negative samples with concordant results, no residual disease was detected by either assay (CPM = 0 for both). When evaluating sex, race, ethnicity, chromosomal abnormalities, prior treatments to sample collection (immunomodulatory drugs, proteasome inhibitors, CD38 antibodies, CAR Ts/bispecific antibodies), and disease stage (NDMM, RRMM, untreated), patients with t(11;14) were significantly higher in the discordant group (17.9% concordant vs. 32.9% discordant; p = 0.016), while CAR T/bispecific antibody-treated patients were more likely concordant for the tests (27.2% concordant vs. 4.1% discordant; p<0.01). High-risk cytogenetics (t(4;14), t(14;16), gain 1q) were associated with worse survival (HR 6.22, 95% CI 2.02 – 19.2; HR 16.2, 95% CI 3.38-77.1; HR 4.0, 95% CI 1.28 – 12.5, respectively). Discordant MRD status did not impact survival, though only 13/246 patients were deceased (median follow-up approximately 50.6 months).Conclusion: ClonoSEQ demonstrates higher sensitivity compared to NGF for MRD detection in MM, identifying residual disease missed by NGF particularly in t(11;14) cases. Discordance did not affect survival, however, only 13 patients were deceased at the time of last follow up, suggesting longer follow up is needed.

Abstract Introduction Bruton tyrosine kinase inhibitors (BTKis) have changed the treatment algorithm for patients with high-risk relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Efficacy was demonstrated for zanubrutinib and ibrutinib in high-risk R/R CLL patients in the ALPINE (NCT03734016) trial, for ibrutinib and acalabrutinib in the ELEVATE-RR (NCT02477696) trial, and for acalabrutinib in the ASCEND (NCT00135226) trial. While there is limited head-to-head comparative trial data of all covalent BTKis in the treatment of high-risk R/R CLL, a previously published network meta-analysis (NMA) used data from the ALPINE, ELEVATE-RR, and ASCEND trials, and reported that zanubrutinib demonstrated significantly improved relative efficacy compared to ibrutinib and acalabrutinib in high-risk R/R CLL (Shadman 2025). Within this NMA, high-risk R/R CLL populations were defined based on the prespecified definitions within each trial, including patients with del(17p) and/or TP53 mutations in the ALPINE and ASCEND trials, and del(17p)/del(11q) in the ELEVATE-RR trial. This study aimed to compare zanubrutinib versus ibrutinib and acalabrutinib in high-risk R/R CLL by calculating the number needed to treat (NNT) to avoid one progression or death. Methods A model was developed to evaluate the NNT among high-risk R/R CLL patients to avoid a progression or death. Progression free survival (PFS) data for zanubrutinib in high-risk patients were extracted from the ALPINE trial. PFS values for ibrutinib and acalabrutinib were derived from the previously published NMA study. PFS for ibrutinib and acalabrutinib were calculated by applying PFS hazard ratio from the NMA results to the zanubrutinib PFS value for the high-risk population in the ALPINE trial. 24-month PFS (72.6% for zanubrutinib, 52.0% for ibrutinib, and 55.9% for acalabrutinib) were used for the base case analysis of the model. Sensitivity analyses were conducted to examine the impact of alternative PFS inputs for ibrutinib, derived directly from the high-risk populations in ALPINE trial (unadjusted). Results The base case results from the NNT model indicate that for the treatment of patients with high-risk R/R CLL over 24-months, every five patients treated with zanubrutinib instead of ibrutinib results in the avoidance of one disease progression or death and every six patients treated with zanubrutinib instead of acalabrutinib results in the avoidance of one disease progression or death. Applying the model result to a hypothetical scenario of 100 patients with high-risk R/R CLL treated with zanubrutinib versus ibrutinib for two years finds approximately 20 patients will avoid disease progression events or deaths. Treating the same population with zanubrutinib versus acalabrutinib for two years will result in the avoidance of 17 disease progression events or death. Sensitivity analysis showed consistent NNT results.Conclusions The NNT analysis suggests that among high-risk R/R CLL patients, zanubrutinib is associated with more favorable clinical outcomes compared to ibrutinib and acalabrutinib. Over 24 months, zanubrutinib demonstrated a NNT of five to prevent one disease progression or death compared to ibrutinib, and an NNT of six compared to acalabrutinib, in high-risk R/R CLL patients. Study findings should be interpreted based on modeling assumptions and potential patient population differences across trials.

Abstract Background: Eltrombopag and romiplostim are thrombopoietin receptor agonists approved for treating thrombocytopenia in various conditions. Post-marketing surveillance data provide valuable insights into their real-world safety profiles. Objective: To analyze adverse event reports for eltrombopag and romiplostim from the FDA Adverse Event Reporting System (FAERS) database to characterize their safety profiles and identify potential safety signals. Methods: We analyzed FAERS reports for eltrombopag and romiplostim from 2015 to 2024. Reports were classified by System Organ Class (SOC), seriousness criteria, patient demographics, time to onset, and clinical outcomes. Descriptive statistics were used to characterize adverse event patterns. Results: A total of 3500 adverse event reports were identified (eltrombopag: n=2262; romiplostim: n=1238). Mean patient age was 57.5 years for eltrombopag and 58.5 years for romiplostim, with female predominance (57.6% and 56.4%, respectively). For eltrombopag, the most frequently reported adverse events were hepatic disorders, with 29.8% of reports involving hepatobiliary events. The top adverse events included ALT increased (n=124), bilirubin increased (n=120), jaundice (n=117), AST increased (n=109), and hepatic failure (n=107). Thrombotic events occurred in 20.5% of eltrombopag reports. The serious adverse event rate was 51.3%, with a mortality rate of 3.3%. For romiplostim, injection site reactions were the most common adverse events, occurring in 18.3% of reports. The most frequently reported events were injection site reaction (n=80), injection site erythema (n=76), and injection site pain (n=71). Thrombotic events occurred in 23.3% of romiplostim reports. The serious adverse event rate was 48.6%, with a mortality rate of 2.7%. The median time to onset was similar for both drugs (eltrombopag: 74 days; romiplostim: 73 days), with most events occurring within 90 days of treatment initiation. Geographic distribution showed predominant reporting from the United States, followed by Japan and European countries. Conclusions: This FAERS analysis confirms known safety profiles of both thrombopoietin receptor agonists. Eltrombopag demonstrates a clear hepatic safety signal requiring regular liver function monitoring, while romiplostim shows expected injection site reactions. Both drugs exhibit similar rates of thrombotic complications. These findings support current prescribing guidelines emphasizing the need for appropriate patient monitoring and risk-benefit assessment in clinical practice. Keywords: eltrombopag, romiplostim, thrombopoietin receptor agonists, FAERS, pharmacovigilance, thrombocytopenia, adverse drug reactions

Abstract Introduction Management of acute leukemia (AL) during pregnancy remains challenging. In the first trimester, chemotherapy is toxic to the fetus, while delaying treatment may endanger maternal health, often prompting recommendations for pregnancy termination. In later trimesters, although the risk of congenital malformations decreases, complications such as preterm labor remain prevalent. Delivery prior to chemotherapy may be considered in advanced gestation. This study aimed to describe maternal and fetal outcomes of patients diagnosed with AL during pregnancy. Methods Following institutional review board approval, we retrospectively identified pregnant patients diagnosed with AL between 1995 and 2025 across Mayo Clinic sites (Minnesota, Arizona, Florida). We recorded leukemia subtype, treatment course, maternal and fetal outcomes. Results We identified 18 patients diagnosed with AL during pregnancy, including 11 with acute myeloid leukemia (AML) and 7 with acute lymphoblastic leukemia (ALL). Ten were diagnosed in the first trimester, 3 in the second, and 5 in the third. In the AML group (n=11; median age 30 years, range 18-42), one patient had acute promyelocytic leukemia (APL). ELN 2022 risk stratification was favorable in 5 (45%), intermediate in 4 (36%), and adverse in 2 (18%). In the ALL group (n=7; median age 23 years, range 19-34), 5 had B-ALL (one Philadelphia chromosome-positive) and 2 had T-ALL. All ALL cases were diagnosed in the first trimester. Among first-trimester AMLs, 2 of 3 had core-binding factor (CBF) AML. All eight patients diagnosed in the second and third trimesters had AML (1 APL, 2 CBF AML, 1 KMT2A-rearranged, 1 with DEK::NUP214 fusion, 1 complex karyotype including t(8;21), 2 with normal karyotype). Overall, 15 (83%) patients achieved complete remission (CR) or CR with incomplete count recovery (CRi) after initial induction. One patient had refractory disease and achieved partial remission after salvage, another had refractory disease and achieved CR after multiple lines of therapy, and a third achieved CR after FLAG-idarubicin and revumenib. Five patients received chemotherapy during pregnancy (3 in the first trimester, 1 in the second, 1 in the third); two of these resulted in live births. Among the 10 patients diagnosed in the first trimester, all underwent therapeutic or spontaneous abortion. Of the 3 second-trimester diagnoses, 2 underwent spontaneous or therapeutic abortion at 15 weeks. The third received 7+3 induction at 24 weeks for KMT2A-rearranged AML, followed by preterm delivery at 26 weeks and re-induction with FLAG-idarubicin plus revumenib, achieving CR. Among the 5 third trimester diagnoses, 4 delivered preterm infants (median gestational age 33 weeks) prior to chemotherapy. One patient received 7+3 at 29 weeks and delivered a viable preterm infant at 36 weeks. At a median follow-up of 6.5 years, 5 of 11 patients with AML (45%) and 3 of 7 patients with ALL (43%) died, mostly due to disease progression. Median overall survival was not reached in either group. Causes of death were as follows: 1 of AML, 1 of ALL, 3 of acute stem cell transplant (SCT) complications, 1 of chronic SCT complications, 1 of Hodgkin lymphoma, and 1 of pneumonia. Among patients diagnosed in the second and third trimesters (n=8, all with AML), 6 (75%) resulted in live births: 5 of 5 (100%) third-trimester diagnoses and 1 of 3 (33%) second-trimester diagnoses. All received intensive induction: 7+3 (n=5), 7+3 + ATRA (n=1), 7+3 + gilteritinib (n=1), and 7+3 + nilotinib (n=1). Of the second-trimester group, only one received induction prior to delivery; she later achieved CR with FLAG-ida and revumenib. Among the third-trimester group, one patient received chemotherapy prior to delivery and achieved CR followed by SCT. All but one of the 8 AML patients achieved CR after initial therapy. Conclusions Successful pregnancy outcomes were achieved in 75% of patients diagnosed with AML during the late second or third trimester. Notably, 5 (28%) of patients received chemotherapy during pregnancy. Larger, multi-institutional cohorts are warranted to further characterize the incidence and outcomes of AL in pregnancy.

Abstract Background: Autoimmune hemolytic anemia (AIHA) is a condition in which the immune system erroneously attacks and damages red blood cells. While the epidemiology of AIHA has been examined in various European and Asian nations (Hansen 2020; Kao 2025), there is limited data available from the United States (US). Using US insurance claims data, this research aimed to determine the prevalence and demographic characteristics of AIHA over a five-year span. Methods: Five databases were used: Merative MarketScan Commercial Claims and Encounters; Optum's de-identified Clinformatics® Data Mart Database; Closed and Open claims sourced through HealthVerity; Merative MarketScan Medicare Supplemental Database; Merative MarketScan Multi-State Medicaid. AIHA was defined by ICD-10 diagnosis codes D59.1x in a given calendar year and a second code within 365 days prior. Annual prevalence in years 2019 – 2023 was calculated among people with insurance enrollment for at least 6 months in the calendar year. Annual prevalence was stratified by age group, sex, and prescription fill for an AIHA-related treatment (systemic steroids, immunosuppressants [azathioprine, mycophenolate, cyclosporin, cyclophosphamide, danazol, bortezomib, rituximab], splenectomy) in the calendar year. Extrapolation of prevalence rates for commercial and government assistance insurance to the US population for 2023 was implemented by age and sex-standardization to the US Census population. For data sources that included both commercial and government assistance insurance, patients aged <65 years were analyzed as commercial insurance and aged ≥65 years as government assistance. Results: AIHA prevalence in 2023 across databases ranged from 2.7 to 4.3 per 100,000 for ages <18 years; 4.2 to 9.4 per 100,000 for ages 18 – 34 years; 8.2 to 11.8 per 100,000 for ages 35 – 49 years; 15.4 to 23.9 per 100,000 for ages 50 – 64 years; 26.6 to 37.0 per 100,000 for ages 65 – 74 years; and 30.6 to 61.2 per 100,000 for age 75 years and older. Across databases and over time, the proportion of AIHA patients that were female was 55% – 67%. Across all databases, in year 2023, half (44% - 55%) of patients received any AIHA-related treatment, out of which one third (26%-34%) received systemic steroids, less than one quarter (9% – 17%) received rituximab, and one third (25% – 31%) received a different immunosuppressant. Compared to patients with commercial insurance, Medicaid-insured patients had lower AIHA-related treatment utilization, whereas Medicare-insured patients had higher utilization. Within age group and sex and by insurance type, low and high estimates of prevalence were used to define a range of prevalence. After standardization to the 2023 US Census population, the estimated prevalence in 2023 ranged from 38,459 to 57,235 patients diagnosed with AIHA, corresponding to prevalence rates of 11.6 to 17.3 per 100,000. This marked an increase from 2019 US Census-standardized estimates of 32,777 to 48,482, with corresponding prevalence rates of 10.1 to 14.9 per 100,000. Discussion: AIHA prevalence was higher in older age groups, with a peak prevalence in ages 65 and older. Prevalence increased approximately 15% over a 5-year interval and was notably higher in patients with commercial health insurance compared to government insurance programs, which may in part be due to the older age of the Medicare population. Fewer than half of patients received an AIHA-related treatment in 2023, which could reflect heterogeneity in disease severity necessitating treatment, in addition to the relapse-remitting nature of AIHA whereby patients experience remission for periods of time. Additionally, insurance claims do not specify an indication for treatment nor a reason for discontinuation; some treatments could have been prescribed for an underlying condition contributing to AIHA. Finally, prevalence extrapolation assumes Americans without health insurance are diagnosed with AIHA at the same rate as those with insurance, which may slightly overestimate the total number of diagnosed patients.Conclusion: AIHA prevalence in this study was consistent with estimates from European countries and has been increasing in recent years, providing evidence of consistent disease epidemiology across several geographies.

Abstract Introduction: CTCLs are rare, heterogeneous non-Hodgkin lymphomas (NHL) with significant regional variability in treatment patterns. Prospective studies characterizing CTCL management, particularly in racially and ethnically diverse populations, remains limited. The LEO-MER multi-center prospective cohort study (NCT02736357) is designed to address the persistent disparities in outcomes research by enrolling historically underrepresented groups of patients diagnosed with lymphoma across the United States (US). Here, we present a real-world analysis of CTCL patients that reflects US academic practice, evaluating treatment patterns, as well as prognostic factors influencing survival outcomes. Methods: Patients aged ≥18 years with newly diagnosed CTCL were prospectively enrolled in either the University of Iowa/Mayo Clinic MER cohort (2002-2015) or the expanded LEO cohort (2015-2020), which included 8 US academic centers. Standardized protocols were used to abstract clinical, pathologic, treatment, and outcome data from medical records. ANOVA/Kruskal-Wallis and Fisher's/chi-square tests were used to compare patient distribution across demographic and clinical characteristics based on data distribution and sample size. Overall survival (OS) was calculated from diagnosis to death or last follow-up. Survival analyses employed Kaplan-Meier estimation supplemented by Cox proportional hazards modeling. Results: The LEO-MER cohort enrolled 223 CTCL patients (91 MER and 132 LEO). Subtypes included mycosis fungoides (MF, n=155, 69.5%), Sézary syndrome (SS, n=22, 9.9%), primary cutaneous anaplastic large-cell lymphoma (n=17, 7.6%), subcutaneous panniculitis-like T-cell lymphoma (n=11, 4.9%), cutaneous CD4+ small/medium T-cell lymphoproliferative-disorder (n=9, 4%), and other rarer CTCL subtypes (n=9, 4%). Among the MF/SS cohort, median age was 64 years (Range: 18-89 years), 58.2% (n=103) were male and race/ethnicity distribution included White (n=123, 69.5%), Black (n=29; 16.4%) and others/unknown (n=25; 14.1%). Stage distribution included 62.7% with early-stage (ES) MF (IA-IIA, n=111), 37.2% with advanced-stage (AS) MF (IIB-IVB, n=66). To complete diagnostic workup, T-cell receptor (TCR) testing was performed in 52.6% of skin biopsies (n=92) and 62.5% of blood samples (n=110), with clonal detection rates of 75% (69/92) in skin and 51.8% (57/110) in blood. Paired TCR matching between skin and blood samples was performed in 31.6% (n=56) of cases, demonstrating 53.6% (30/56) concordance. Blood flow cytometry data were reported in 80.1% (89/111) and 84.4% (56/66) of ES and AS MF cases, with T-cell population being detected in 7.2% (8/111) and 62.1% (41/66) of ES and AS cases. Nodal biopsies were obtained in 23.4% (n=41) of patients and clonality assessment was reported in 18.6% (33/177) of these cases. The MF/SS cohort's lifetime treatment exposure data (n=160) revealed topical skin-directed therapies alone (n=49, 31.8%) as the most common approach followed by lifetime exposure to topical skin-directed and systemic therapies (n=45, 29.2%) followed by multimodal exposure of topical skin-directed, radiation and systemic treatments (n=30, 19.5%). Only 5.6% of patients were enrolled in a clinical trial. First-line (1L) systemic regimens were predominantly a) immunomodulatory agents (n=47, 29.3%); including oral retinoid (n=20), extracorporeal photopheresis (n=18), interferon (n=9) followed by b) chemotherapy (n=30, 18.7%) and c) targeted therapies (n=17, 10.6%) including Brentuximab Vedotin (n=6), Romidepsin (n=5), Mogamulizumab (n=3), Vorinostat (n=2) and Pralatrexate (n=1). Multivariable analysis predicting 1L systemic treatment initiation demonstrated a significant association with presence of N2/N3 stage (N2/N3 vs N0/N1: Odds Ratio (OR): 5.45) and elevated LDH (OR: 5.30). At median follow-up of 91.1 months (mon), median OS was 122.3 mon (95% confidence interval 67.2-159.2 mon). In subset analyses, Black race (p=0.001) and SS (p=0.0001) were associated with worse OS outcomes. Conclusion: We present initial data from our prospective LEO-MER cohort, a large US-based multicenter consortia. Our findings demonstrate variability in both diagnostic staging and treatment approaches for MF/SS patients. The cohort demonstrated worse outcomes with high-risk disease and Black race/ethnicity. These findings warrant further study on the impact of underlying social determinant factors, given the variability noted in this population.

Abstract Introduction: Adult T-cell leukemia/lymphoma (ATLL) is a rare blood disorder associated with human T-cell leukemia virus type 1 (HTLV-1) infection. It is generally categorized into four subtypes: smoldering, chronic, lymphoma, and acute. Given the heterogeneity of these subtypes, there is a significant difference in outcomes. Robust and contemporary epidemiological data are lacking for this rare disorder. We present a retrospective cohort study of patients with ATLL, utilizing the National Cancer Database (NCDB) to better characterize the epidemiology and survival trends in the United States. Methods: This is a retrospective cohort study using the NCDB to identify ATLL cases diagnosed from 2004-2020. Descriptive statistics summarized baseline characteristics, while chi-square tests assessed group differences. Overall survival (OS) was estimated using Kaplan-Meier analysis and compared using log-rank tests. Multivariable Cox proportional hazards models identified independent prognostic factors (p < 0.05 considered significant). Results: A total of 635 patients were identified with ATLL, including 344 (54%) males and 291 (46%) females, with a median age at diagnosis of 59 years (range: 19-90). Most patients came from the Middle Atlantic (NY, NJ, PA) region (33%), followed by the South Atlantic (DC, DE, FL, GA, MD, NC, SC, VA, WV) region (20%) and the East North Central (IL, IN, MI, OH, WI) region (8%). Of the 635 patients, 335 (52%) were Black, 247 (39%) White, and 26 (4%) Asian. Sixty-five (10%) patients were of Hispanic origin. Over half of patients with ATLL (54%) had a median income below $46,000. International Prognostic Index (IPI) score was only available for 16 patients: three (19%) patients were in the high-risk group, 7 (43%) in the high-intermediate group, and 6 (37.5%) in the low-intermediate group. Treatment groups included 357 (56%) patients treated with chemotherapy and 29 (4.5%) who received radiation therapy. Thirty-three (5%) patients underwent hematopoietic stem cell transplant (HSCT), including 27 autologous and 16 allogeneic transplants. The median survival time in the cohort was 9 months (95% CI 7.3-10.7). One-year OS rate in the cohort was 43%, while 2-year and 5-year OS rates were 31% and 23.5%, respectively. Patients over the age of 65 had a significantly shorter median OS than those under 65 (4 vs. 11 months, p=0.001) and were significantly less likely to undergo HSCT (p< 0.001). Black patients had significantly shorter median OS compared to White patients (7.8 months vs 13.3 months, p=0.014), despite similar treatment rates with chemotherapy and HSCT. Median OS appeared to improve over time, from 8 months in patients diagnosed between 2004-2009 to 10 months for those diagnosed between 2016-2020, although this was not statistically significant (p=0.145). Treatment with allogeneic HSCT was associated with significantly prolonged median survival, compared to those who did not receive transplant (50 months vs. 7 months, p<0.05). Additionally, receiving chemotherapy and/or radiation compared to not receiving treatment was also associated with significantly prolonged median survival (p<0.05). Patients treated in the Middle Atlantic region had a median survival of 8.8 months, compared to 23.2 months in the West South Central (AR, LA, OK, TX) region (p< 0.001). Increased education and income levels were not significantly associated with improved survival. There were no significant differences in survival between males and females. Conclusions: We provide contemporary estimates on the epidemiology of ATLL. Factors associated with improved prognosis included undergoing HSCT, radiation, or chemotherapy. We report that increased age and Black race are negative prognostic factors. Regional differences in incidence and survival persist in the US. Our study findings underscore the need for increasing access to treatment, including HSCT for those who are good candidates. Additionally, there remains work to be done to address racial disparities in the care of patients with ATLL.

Abstract Introduction: CSF3R mutations (CSF3RMUT), most commonly T618I, represent the defining genomic alteration in chronic neutrophilic leukemia (CNL), present in ~80% of cases. Despite emerging real-world data, information on treatment outcomes and prognostic factors remains limited due to rarity of the disease. In this two-center retrospective study, we examined clinical and molecular predictors of treatment response, overall survival (OS), and blast transformation (BT) and outcome following allogeneic stem cell transplant (ASCT). Methods: The study was approved by the institutional review boards of the Mayo Clinic (USA) and the University of Montreal (Canada). Electronic medical records were reviewed to identify patients with CSF3R mutated CNL at both institutions and extract relevant data. Statistical analyses were conducted using JMP Pro 17.0.0 software (SAS Institute, Cary, NC, USA). Results: Forty-four patients (68% male, median age 68 years [range: 26-93]) were included. At diagnosis, 20 (56%) were asymptomatic, 13 (36%) presented with constitutional/non-specific symptoms, and 20 (50%) had antecedent leukocytosis at a median of 13 months(mo) prior. Splenomegaly (palpable or radiological) was observed in 28 (67%) patients, hepatomegaly in 7 (17%) and lymphadenopathy in 4 (9.8%). Median white blood cell count (WBC) was 52×10⁹/L (range: 17-390). CSF3RMUT/variants included 39 (89%) with T618I (7 of the 39 had additional CSF3RMUT), 2 (5%) with M696T, and 1 (2%) each for I598I, Q739* and T640N. Frequent co-mutations included ASXL1 in 25 (63%) patients, SETBP1 in 14 (36%), and SRSF2 in 8 (31%), with overlapping occurrence; 10 (38%) patients had ≥2 of these 3 mutations. Ten patients (median WBC 29 x10⁹/L [range: 19–58]), were initially observed without treatment for a median of 8.6 mo; 2 remained on observation alone at 46 and 77 mo. Hydroxyurea (HU) alone or in combinations excluding ruxolitinib (Ruxo) was the most common first-line treatment (68%). Second-line therapies included Ruxo (39%), HU (25%), and hypomethylating agents (14%). WBC response (≥50% reduction from baseline) was 78% with HU vs. 60% with Ruxo (p=0.2). WBC response to HU was lower with abnormal karyotype (40% vs. 94%; p=0.02). WBC response to Ruxo was lower with SETBP1MUT (0% vs. 72%; p=0.05) and with male sex (40% vs. 100%; p=0.04). Seven patients underwent ASCT, including 2 after BT; four (57%) of the 7 remain alive, including 2 without evidence of disease (both 45 mo post-ASCT; one harbored ASXL1MUT) and the other 2 with active disease (both harbored ASXL1MUT). Three patients died from veno-occlusive disease (Day+34), CNS relapse with AML (at 105 mo post-ASCT), or unrelated causes (at 44 mo post-ASCT). Median OS was longer in transplanted patients (115 vs 23 mo; p=0.03). At a median follow-up of 44 mo for living patients, disease transformation occurred in 10 patients, including 7 with BT (6 with T618I, 1 T640N) and 3 with chronic myelomonocytic leukemia (2 M696T, 1 T618I). BT rate at 2, 3, and 5 years was 15%, 31%, and 43%, respectively. Univariate analysis (UVA) identified male gender (p<0.01), >5% immature WBCs (p=0.02), platelets <160×10⁹/L (p=0.04), higher WBC (p=0.02), and ASXL1 or SETBP1 mutation (p<0.01) as risk factors for BT. On multivariable analysis (MVA), only the latter remained significant. Median OS was 26 mo (95% CI: 21-43) for the entire cohort; 24 mo for patients with T618I CSF3RMUT vs 53 mo with other CSF3RMUT, p=0.1. In UVA, age >60 years (HR 5.0, p=0.03), platelets <160×10⁹/L (HR 3.4, p=0.006), WBC >50×10⁹/L (HR 2.6, p=0.02), and ASXL1 or SETBP1 mutations (HR 4.2, p=0.01) were associated with shorter OS. In MVA, age >60 (HR 6, p=0.03), WBC >50×10⁹/L (HR 12, p<0.01), and the presence of ASXL1MUT or SETBP1MUT (HR 9.5, p=0.01) remained significant. Based on the HRs on MVA, one adverse point was allocated for age >60 years, and two adverse points each for WBC >50×10⁹/L and presence of ASXL1 or SETBP1 mutations. Patients were accordingly stratified into low (0-2 points), intermediate (3) and high (4-5) risk groups with corresponding median OS of “not reached”, 29 mo, and 16 mo (p<0.01). Causes of death included disease progression (82%), infection/bleeding (9%), and ASCT complications (9%). Conclusion: The current study highlights the prognostic relevance of “SETBP1 or ASXL1” mutation for both overall survival and risk of blast transformation. The study also signifies variable natural history and potential benefit from ASCT.

Abstract Background: The International Consensus Classification (ICC) for systemic mastocytosis (SM) recognizes mast cell leukemia (MCL) and SM with associated myeloid neoplasm (SM-AMN) as distinct categories of advanced SM (SM-Adv; Arber et al. Blood 2022;140:1200). Contemporary risk models in SM, including the Mayo Alliance Prognostic System (MAPS), do not account for the prognostic heterogeneity among ICC-defined SM-Adv subcategories. Methods: Mayo Clinic databases were utilized to access patient information. Diagnoses of SM and its morphological subcategories were confirmed through clinical evaluations and review of BM pathology. Diagnostic criteria were retrospectively fitted to be consistent with those of the ICC (Arber et al. Blood 2022;140:1200); diagnosis of MCL required the presence of immature cytomorphology of mast cells and only myeloid neoplasms were listed under the category of SM-AMN.Next-generation sequencing and cytogenetic studies was performed in a subset of the study patients according to previously described methodologies. Statistical analyses were conducted on clinical and laboratory data collected at the time of initial diagnosis while survival analysis was censored at the time of allogeneic stem cell transplant (ASCT). Results: A total of 910 Mayo Clinic patients with SM (median age 56 years, range 12-89; males 50%) were accessed in order to conduct a series of multivariable analyses (MVA) in search of independent risk factors for transplant-censored overall survival (OS). All patients were evaluable for assignment to specific ICC categories of SM: indolent (ISM; N=553), aggressive (ASM; N=114), SM-AMN (N=235), and MCL (N=8); the AMN components in SM-AMN included acute myeloid leukemia (N=18), chronic myelomonocytic leukemia (N=70), myelodysplastic syndromes (N=32), MDS/myeloproliferative overlap (N=81), myelofibrosis (N=7), polycythemia vera or essential thrombocythemia (PV/ET; N=19), and others (N=8). In addition, subsets of patients were evaluable for hemoglobin level (N= 865), white blood cell count (WBC; N=858), platelet count (N= 859), serum alkaline phosphatase (ALP; N=761), serum tryptase level (N=706), karyotype (N=574), and mutations (N=240). Median follow-up for living patients was 70 months (range, 0-520); during this time 346 (38%) deaths, 16 leukemic transformations, and 20 ASCTs were documented. ROC analysis-determined optimal cutoff levels for predicting OS included age at ≥60 years, platelet count <150 x 109/L, tryptase level ≥100 ng/mL, WBC ≥10 x 109/L, hemoglobin below sex-adjusted lower limit of normal (anemia), and ALP >210 U/L in women or >170 U/L in men (increased). All except WBC ≥10 x 109/L retained significance during MVA that included ICC-specified SM categories: MCL (HR 74.8, 26.0-215.3; p<0.01); SM-AMN (HR 3.9, 2.5-6.0; p<0.01); ASM (HR 2.2, 1.4-3.5; p<0.01); age ≥60 years (HR 3.3, 2.2-4.7; p<0.01); platelets <150 x 109/L (HR 2.8, 2.0-3.9; p<0.01); tryptase ≥100 ng/mL (HR 2.1, 1.5-2.9; p<0.01); anemia (HR 1.7, 1.1-2.4; p<0.01); and increased ALP (HR1.5, 1.1-2.0; p=0.01). A subsequent HR-weighted risk model effectively delineated 5 risk levels ranging in median survivals from 11 months to 372 months (Figure 1). Figure 2 outlines complementary subtype-specific risk models; to that end, risk factors for ISM included age ≥60 years (HR 4.5, 2.5-7.9), tryptase ≥100 ng/mL (HR 3.5, 2.1-6.0); platelets <150 x 109/L (HR 3.4, 1.5-7.9), and anemia (HR 2.4, 1.2-4.8); for ASM age ≥60 years (HR 2.3, 1.3-4.3), platelets <150 x 109/L (HR 2.4, 1.4-4.0), and anemia (HR 2.0, 1.2-3.4); and for SM-AMN age ≥60 years (HR 2.9, 1.6-5.2), platelets <150 x 109/L (HR 2.5, 1.6-3.9), and tryptase ≥100 ng/mL (HR 2.5, 1.6-3.9) [Figure 2]. In SM-AMN, additional prognostic relevance from subcategorization into PV/ET vs. all other types of AMN was appreciated (Figure 3; HR 4.0, 1.6-3.9) and incorporated into the risk model for SM-AMN (Figure 2). Abnormal karyotype (AK) and high risk mutations(HRM; ASXL1, SRSF2, RUNX1, NRAS)clustered withSM-AMN with AK and ASXL1MUT displaying independent prognostic relevance that was most apparent in SM-AMN. Conclusions : MAPS-R relies on the prognostic eminence of ICC-defined morphologic subcategories and allows for additional SM subtype-specific risk stratification. SM associated with ET or PV is a prognostically unique subcategory of SM-AMN and should be recognized as such in future classification schemes. SM-AMN must be thoroughly ruled out in the presence of AK or HRM.

Abstract Background and Significance Somatic gain-of-function mutations in the PIK3CA gene can result in a range of vascular malformations (VMs). These rare disorders include lymphatic anomalies and PIK3CA-related overgrowth spectrum (PROS). VMs are noncancerous lesions that may be managed with treatments such as surgery, sclerotherapy, sirolimus, and non-mutant-selective PI3Kα inhibitors; however, use of systemic therapies in patients is frequently limited by drug-related adverse effects. In particular, inhibition of wild-type PI3Kα results in significant toxicity, including hyperglycemia, diarrhea and rash. RLY-2608 is a novel, allosteric, pan-mutant and isoform-selective oral PI3Kα inhibitor designed to have higher potency and improved tolerability. In a PIK3CAH1047R HUVEC xenograft mouse model, RLY-2608 demonstrated greater lesion regression and less insulin induction across clinically relevant dose levels than alpelisib (Llambi, VAC 2025). ReInspire (RLY-2608-201; NCT06789913) is an ongoing, global, multicenter study in patients with PIK3CA-driven VMs to assess the safety, pharmacokinetics, recommended adult and pediatric dosing, and efficacy of RLY-2608 based on target lesion volume and clinical outcome assessments. The design of this study, including dose selection, was informed by clinical data from the first-in-human study of RLY-2608 in adult patients with advanced solid tumors, including breast cancer (Varkaris et al, 2024). Study Design and Methods ReInspire is a 3-part study evaluating the safety and efficacy of RLY-2608 in approximately 277 patients two years of age and older with PIK3CA-driven VMs and PROS. RLY-2608 is administered orally in continuous cycles. The primary endpoints are safety, tolerability, recommended Phase 2 dose (RP2D), and efficacy of RLY-2608 per volumetric reduction on MRI (≥20% reduction from baseline to Week 24 in the sum of target lesion volumes) by blinded independent central review. Other endpoints include duration of response and change in age-appropriate clinical outcome assessments. Patients are enrolled in a staggered fashion by age, beginning with adult and adolescent participants 12 years and older (Group 1), and may be extended to pediatric participants 6 to <12 years (Group 2) and 2 to <6 years, based on review of cumulative clinical data. Part 1 is the open-label dose-finding portion, which initiates with randomization of Group 1 patients (n=45) to one of three dose levels with stratification according to prior alpelisib use, and will be followed by weight-based dose escalation using a Bayesian optimal interval (BOIN) design in Groups 2 and 3, if opened. Part 2 is a basket-style, open-label dose expansion that will evaluate the clinical activity of RLY-2608 at one or more RP2Ds in various populations in cohorts of 20 patients each based on Part 1 findings. Depending on the results of Parts 1 and 2, Part 3, a double-blinded, placebo-controlled, 2:1 randomized study (n=90), may be opened to patients 6 years of age and older. To enroll, patients are required to have a clinical diagnosis of PROS or a malformation within the ISSVA classifications, and the majority must have a documented activating PIK3CA mutation per local assessment of lesional tissue and/or cell-free DNA from the lesion or blood. Patients with other known pathogenic somatic or germline driver mutations (such as TIE2 (TEK) and AKT1) are not eligible. Patients must be a candidate for investigational systemic therapy; have severe, symptomatic, and/or progressive disease; and at least one target lesion amenable for volumetric assessment. Additionally, patients who have received disease-directed therapy must undergo a washout period for systemic treatment and local therapies including radiation, surgery and other procedures. Patients with Type 1 or 2 diabetes requiring antihyperglycemic medication or fasting plasma glucose ≥140 mg/dL, or glycosylated hemoglobin (HbA1c) ≥7.0% (≥53 mmol/mol) are not eligible. Statistical analyses will be primarily descriptive in nature in Parts 1 and 2, with statistical comparisons between RLY-2608 and placebo at Week 24. ReInspire is open to enrollment. Patients ≥12 years are now enrolling in Part 1. For more information, contact clinicaltrials@relaytx.com