Andres, Erica

e18508 Background: BPDCN is a rare and aggressive hematologic malignancy. Despite the advent of targeted therapies, median overall survival (mOS) remains <1 year (y) in the absence of stem cell transplant (SCT). This study evaluates clinical and molecular predictors of outcomes in a large cohort of BPDCN patients at a tertiary center. Methods: BPDCN patients seen at Mayo Clinic (AZ, FL, MN) between 2000-2024 were identified retrospectively. Analyses considered parameters at diagnosis. Next generation sequencing (NGS) was performed using a 47-gene assay. Standard statistical methods were used; calculations used R. Results: Among 69 patients, the median age was 70y (range 19-94) with male predominance (83%). At presentation, skin (80%), bone marrow (73%), lymph nodes (52%), spleen (27%), and CNS (12%) were involved; 26% had a concurrent hematologic malignancy. Among 20 cases with NGS, the median number of mutations was 3 (range 0-5), most frequently TET2 (n=16), ASXL1 (n=13), SRSF2 (n=7), and NRAS (n=5). Frontline therapy (Table) yielded a complete response (CR) rate of 63% and overall response rate of 76%. CR rates were similar among regimens, but patients who received an ALL (hyper-CVAD based) regimen (8/13) or tagraxofusp (6/9) were more likely to be bridged to SCT (6/29, p<0.01). After median follow up of 38 months (mo), mOS for all was 15 (95% CI 12-21) mo; 44 (64%) were deceased at last follow up. Among 62 evaluable patients, 20 (32%, median age 60 vs 74y, p<0.01) underwent SCT which improved survival (mOS 51 vs 10 mo, 3y OS 52% vs 5%, p<0.01); mOS was not different between allogeneic (n=17) and autologous (n=3) SCT (54 vs 38 mo, p=0.45). When censored for SCT, the 1y OS for patients receiving an ALL regimen, tagraxofusp, or other regimen was 82%, 67%, and 47%, respectively (p=0.15). In univariate analysis, age ≥50y, lymph node involvement, bone marrow involvement, hemoglobin <10 g/dL, leukocytes (WBC) >11 x10 9 /L, abnormal karyotype, and HCT were significantly associated with OS. In multivariate analysis, WBC >11 x10 9 /L (HR 3.7, p<0.03), abnormal karyotype (HR 5.4, p<0.01), and SCT (HR 0.23, p<0.01) remained significant. Separately, SRSF2 mutation was associated with inferior OS (15 vs 51 mo, p=0.02), but significance was lost when adjusted for age, abnormal karyotype, and SCT. Conclusions: Newly-diagnosed BPDCN patients treated with an ALL regimen or tagraxofusp followed by SCT had longer OS compared to those treated with all other regimens. WBC >11 x10 9 /L and abnormal karyotype were independent predictors of inferior survival whereas SCT was beneficial. Regimen N Age (y) ANNOVA CR Chi Sq HCT Chi Sq 1y OS mOS (mo) Log-rank Tagraxofusp 9 68 (40-70) <0.001 7 (78%) 0.548 6 (67%) 0.018 88% 20.8 0.121 ALL 13 43 (20-72) 8 (67%) 8 (62%) 74% 50.7 Hyper-CVAD 11 43 (20-72) 6 (60%) 6 (60%) 67% 35.8 AML 18 70 (48-80) 13 (76%) 5 (28%) 58% 14.2 Intensive 8 66 (48-77) 7 (88%) 3 (38%) 57% 12.4 HMA+Venetoclax 8 69 (65-80) 6 (75%) 2 (25%) 50% 14.0 Lymphoma 8 74 (49-85) 3 (43%) 1 (13%) 50% 14.0 CHOP 6 74 (49-85) 3 (50%) 1 (17%) 50% 17.7 Other 3 66 (63-73) 1 (33%) 0 (0%) 33% 12.0

9021 Background: Home call is an expected trainee responsibility in many hematology-oncology (HO) training programs although the specific duties and frequency vary. Home call is associated with sleep deprivation and burnout . The Accreditation Council for Graduate Medical Education (ACGME) outlines that home call should not prevent adequate rest or personal time and that the clinical time spent must be counted toward duty hours. However, little is known about the educational value or impact of home call. We sought to analyze the volume, perceived value, and effects of oncology home call on HO fellows. Methods: We completed a review of the pager log of the outpatient/after hours oncology pager (OP) at a single 2059 bed tertiary medical center from 1/1/23-12/31/24. The HO fellow carries the OP afterhours and on weekends except for 7am-12pm on Saturday/Sunday. The pager receives all consult calls from the emergency department and inpatient teams requesting verbal communication (in addition to the electronic order), critical results, and outpatient patient calls on matters related to oncology (hematology not included). Patient calls are not triaged and are routed through the hospital operator directly to the OP. Overnight home call is maximum 3 times per week without a post call day. An optional survey was distributed to fellows in May 2024 to assess fellows’ experiences with the OP using a 5-point Likert scale and free response. Results: There were 80,672 and 87,605 oncology patient visits in 2023 and 2024 respectively at the analyzed institution. The OP received a total of 7,239 pages over the analyzed period. Fellows received a mean of 5.8 pages per weeknight call shift and 8.8 pages per weekend call shift. The survey response rate was 19/33 (42%) HO fellows. Respondents were 58% male and included first (42%), second (26%), and third year (32%) fellows. 89% of respondents reported that most pages overnight were from outpatients and 0 respondents felt that answering patient calls required a physician. Most fellows (79%) did not report educational value from holding the OP and 63% of fellows felt that holding the OP negatively impacted their performance at work the next day. For nights that received more than 3 calls, 95% fellows reported feeling not well rested. In addition, a majority of negative impact on their wellness including anxiety and inability to exercise or socialize when holding the OP. Conclusions: The results from our single-institution study indicate that home call could represent a major opportunity to improve the wellness of trainees without negatively impacting their education. More research is needed to understand what the primary contributors are for the negative experiences and perceptions while developing sustainable systems and approaches for efficiently handling oncology pager traffic.