Abeykoon, Jithma P.

Background: Waldenström Macroglobulinemia (WM) is an indolent lymphoma with heterogeneous outcomes. The recently developed, Revised International Prognostic Scoring System for WM (rIPSS-WM) did not examine the prognostic impact of MYD88L265P, a somatic alteration present in most patients with WM. Moreover, rIPSS-WM could only be partially validated in an external cohort. Here, we report the performance of rIPSS-WM and propose a refined prognostic model with external validation. Methods: We reviewed medical records of treatment-naïve patients with active WM consecutively seen at Mayo Clinic, Rochester (MCR) between 01/01/1996 and 12/31/2017. We applied the rIPSS-WM model in patients with data available for all required parameters, including age, serum beta-2 microglobulin (β2M), serum lactate dehydrogenase (LDH) and serum albumin at diagnosis to assess the prognostic utility of this model. We then identified the dichotomized clinical and laboratory parameters prognostic for overall survival (OS) by univariate analyses (UVA) in our cohort. The significant parameters were analyzed to independently predict OS in a multivariable analysis (MVA) and to create a prognostic model, which was subsequently validated in an independent multi-institutional cohort. Results: We identified 889 patients with active WM at MCR, with a median follow-up of 8.2 [95% confidence interval (CI): 7.5-9] years. The estimated median OS for this cohort was 10.6 (95%CI: 9.7-11.4) years. Patients with available data in this cohort for the validation of rIPSS-WM (n=241) were risk stratified into very low (n=46), low (n=64), intermediate (n=58), high (n=46) and very-high risk groups (n=27) per rIPSS-WM, with the respective 5-year OS rates of 96%, 76%, 72%, 77% and 32%, demonstrating overlapping survival curves for the low, intermediate and the high-risk groups. Because rIPSS-WM could not be validated, we used the data from the MCR cohort and identified age at diagnosis of active WM, LDH >upper limit of normal (ULN), β2M >3µg/mL and albumin <3.5g/dL as statistically significant prognostic markers for OS on UVA. Notably, the presence of MYD88 L265P did not impact OS [median 11.4 years (95%CI: 10.1-not reached (NR) for MYD88 L265P genotype (n=231) versus 10 years (95% CI: 8.1-NR) for MYD88 WT genotype (n=65); p=0.33]. On MVA, LDH >ULN (HR 2.34), serum albumin <3.5 g/dL (HR 1.5) and age groups 65-75 years (HR 1.4) and >75 years (HR 2.6) were independently prognostic. Based on comparable HRs, we assigned a score of 1 point each to serum albumin <3.5 g/dL and age group 66-75 years and similarly, 2 points each for age >75 years and serum LDH >ULN per their impact on OS. Patients with the composite scores of 0, 1 and 2 were categorized as low risk, low- intermediate risk and intermediate risk, respectively. Due to similar OS for the scores of 3 to 5, these were combined to form the high-risk group of our proposed model: Modified Staging System for WM (MSS-WM). The median OS was 14.6 years [95%CI: 9.1 years-NR] for low-risk (score 0, n=71, 21%), 11.2 years (95% CI: 9.1-15.2 years) for low-intermediate risk (score 1, n=110, 32%), 8.1 years (95% CI: 6.4-12.2) for intermediate risk (score 2, n=81, 24%) and 5.5 years (95 % CI: 3.9-11 years) for the high-risk group (score ≥3, n=79, 23%); p<0.0001. In this derivation cohort, the 5-year OS rate was 93%, 82%, 69% and 55% and 10-year OS rate was 60%, 53%, 45% and 30% for the low, low-intermediate, intermediate, and high-risk cohort, respectively ( Figure 1A). We also validated MSS-WM using competing risk analysis (p=0.001) and in the cohort of rituximab treated patients (p<0.0001). We then used data from an independent series of 335 treatment-naïve symptomatic patients from academic institutions (n=5) across the US and Europe for external validation of the MSS-WM model. The median follow-up for the validation cohort was 6.3 years (95% CI: 5.5-7.2 years). The 5-year OS was 93%, 90%, 75% and 57% and the estimated 10-year OS was 91%, 80%, 64% and 35% for the low risk (n= 86, 26%), low-intermediate (n=107, 32%), intermediate (n=86, 26%) and high-risk (n=59, 18%) cohorts, respectively (p<0.0001, Figure 1B). Conclusions: Our proposed model, MSS-WM, is a simple, clinically useful, externally validated model that reliably risk stratifies previously untreated patients with active WM into four groups that have distinct outcomes based on the composite scores derived from the patients' age, serum albumin and serum LDH at diagnosis.

Introduction: Waldenström macroglobulinemia (WM) is a rare B-cell lymphoma that may be preceded by an asymptomatic IgM-monoclonal gammopathy of undetermined significance (MGUS). The mechanisms underlying the progression from IgM-MGUS to WM remain to be fully elucidated; however, the stepwise accumulation of genomic abnormalities has been suggested as a potential driver. Currently, the role of epigenetic regulation of DNA remains underexplored in this disease spectrum. Aberrant DNA methylation is a hallmark of oncogenesis that plays an important role in hematologic malignancies. The aim of this study was to assess differential DNA methylation in WM compared to IgM-MGUS and identify hyper- and hypomethylated pathways that may alter key cellular functions. Methods: This study included 15 patients with WM and 6 with IgM-MGUS. Bone marrow samples were prospectively collected and CD19+ and/or CD138+ B cells were positively selected. Subsequently, genome-wide DNA methylation analysis was performed. CpG methylation ratios were segmented into 200-bp regions and differentially methylated regions (DMRs) comparing WM to IgM-MGUS were identified. DMRs with a Q-value <0.05 and absolute methylation difference of ≥20% were considered significant and utilized for analysis. DMRs were annotated according to genomic regions of interest (promotors, 3'UTR, 5'UTR, introns, exons, CpG islands, CpG shores). Next, genes with significant promotor hyper- or hypomethylation were assessed using the Ingenuity Pathway Analysis. Pathways with a corrected p-value<0.05 were considered statistically significant and a Z-value was calculated based on the degree of differential methylation. Results: Genome-wide DNA methylation analysis revealed a significant number of DMRs (n= 15691, hyper: 8248; hypo: 7443) in WM compared to IgM-MGUS. Assessing genomic regions, promotors (hyper: 1379; hypo: 2403), introns (hyper: 1548; hypo: 2292), CpG shores (hyper: 587; hypo: 849) and 3'UTR (hyper: 66; hypo: 193) regions were observed to have a significantly greater number of hypomethylated DMRs (all comparisons, p<0.001) in WM compared to IgM-MGUS (Figure A). While exons (hyper: 1686; hypo: 1378), CpG islands (hyper: 2128; hypo: 82), and 5'UTR (hyper: 854; hypo: 246) regions had a significantly greater number of hypermethylated DMRs (all comparisons, p<0.001) (Figure A). Next, promotor methylation-based pathway analysis revealed differential methylation of multiple cellular pathways important in WM pathogenesis (Figure B). These included pathways involved in intracellular signaling and the regulation of cellular proliferation, such as the STAT3 and CXCR4 pathways which were hypomethylated, and the PTEN signaling pathway which was hypermethylated. Of interest, we have previously demonstrated the transcription factor, STAT3, to have an increased expression in WM and to be implicated in IgM secretion (Elsawa, 2011). Next, multiple cytokine signaling pathways were observed to be hypomethylated in WM compared to IgM-MGUS including members of the interleukin (IL) family (IL-1, IL-8, IL-15, IL-23), VEGF, and TGF-β. Of relevance, previous studies have demonstrated the elevation of IL-8, IL-15, and increased expression of angiogenic cytokines, including VEGF, in patients with WM (Lewicki, 2010; Anagnostopoulos, 2007). Furthermore, our group has also shown miRNA-based epigenetic regulation of IL-8 and IL-15 in WM compared to IgM-MGUS (Chohan, 2023). Lastly, several pathways critical in the regulation of the cell structure and the extracellular matrix (ECM) were found to be hypomethylated including the FGF, actin cytoskeleton, PAK, and FAK signaling pathways. Of note, the FGF/FGFR axis has been demonstrated to be dysregulated in WM, and its targeting has been shown to halt WM cell growth (Sacco, 2021). Conclusions: This study demonstrates differential DNA methylation of key genomic regions in WM compared to IgM-MGUS. Promotor methylation-based analysis reveals hypomethylation of several important cellular pathways involved in cytokine signaling, cell structure/ECM, and intracellular signaling. These results underscore the influence of epigenetics in the IgM-gammopathy disease spectrum and suggest the potential role of aberrant DNA methylation underlying the malignant progression from IgM-MGUS to WM.

Purpose: Advances in targeted therapeutics for histiocytic neoplasms have led to a growing survivor population, especially for Erdheim-Chester disease (ECD), Langerhans cell histiocytosis (LCH), and Rosai-Dorfman disease (RDD). This growing population is at risk of adverse health-related quality of life (HRQoL) as a result of the disease or treatments received. Patient-reported outcomes in this population remain understudied, and we aim to define their HRQoL using a validated tool. Methods: We enrolled patients from 2 histiocytosis centers and an international conference from Aug 2022-April 2023 to complete the PROMIS © (Patient-Reported Outcomes [PROs] Measurement Information System) 29+2 profile v2.1, which captures 8 domains of physical/mental health and functioning. Domains are reported as T-scores, with 50 being the general population mean. We calculated summary T-scores for Physical Health (PH) and Mental Health (MH), and differences of 3 from general population were considered clinically meaningful. We then used these T-scores to calculate each patient's PROMIS-Preference (PROPr) score, which is a health-utility score that measures overall HRQoL. A mean PROPr score difference of 0.4 from the US population mean of 0.52 was considered meaningful. We ran independent-samples t-tests to examine differences in PH/MH summary scores and PROPr between sub-cohorts. Finally, we performed a multinomial logistic regression analysis to identify factors associated with worse scores, and calculated odds ratios (OR) for each factor. Results: We included a total of 77 participants. Specific diagnoses included ECD (n=33, 42.9%), LCH (n=21, 27.3%), RDD (n=19, 24.7%), and other/unknown (n=4, 5.2%). Median age at diagnosis was 50y (9-79) and at survey was 54y (18-82), with a median 4 year difference between diagnosis and survey completion. Racial demographics included white (n=64, 83.1%), Black (n=12, 15.6%), and Asian (n=1, 1.3%). 4 patients (5.2%) identified as having a Hispanic ethnicity. Disease extent included unifocal (n=13, 16.9%), single system multifocal (ss-M, n=8, 10.4%), single system lung LCH (ss-L, n=3, 3.9%), or multisystem (n=53, 68.8%) disease. The most commonly involved organs included bone (n=44, 57.1%), kidney (n=24, 31.2%), skin (n=24, 31.2%), CNS (n=24, 31.2%), and pituitary (n=19, 24.7%). PH and MH summary scores were lower in various diagnostic categories as compared with the US population, and PROPr scores were reduced in all diagnostic categories. Bone involvement was associated with worse PH (-6.16, 95%CI -10.81, -1.52, [p=0.005]), MH (-7.96, 95%CI -12.48, -3.44, [p=<0.001]), and PROPr (-0.184, 95%CI -0.313, -0.056, [p=0.003]) scores. CNS involvement was associated with worse PH (-4.78, 95%CI -9.14, -0.42, [p=0.016]). We initially constructed a multinomial regression model using diagnosis, race, age at survey completion, and CNS and bone involvement. This model was not statistically significant, and in particular, diagnosis and age did not significantly contribute to the model. We then removed diagnosis and age and constructed a new model using the remaining variables, which was statistically significant for all 3 scores (p<0.05). We found that factors associated with worse PH score were disease involvement of bone (OR=6.19, 95%CI 1.88, 20.43 [p=0.003]) and CNS (OR=10.36, 95%CI 2.01, 53.39 [p=0.005] Figure 2). Factors associated with worse MH scores included female sex (OR=4.12, 95%CI 1.24, 13.66 [p=0.021]) and CNS involvement (OR=10.74, 95%CI 2.47, 46.79 [p=0.002]). Having race/ethnic group other than white/Non-Hispanic or Black was associated with improved MH. However, as this group had only 4 members, the significance of this is uncertain. Finally, CNS involvement was found to be associated with worse odds of having a low PROPr score (OR=10.46, 95%CI 2.17, 50.37 [p=0.003]). Conclusions: Several PROs were worse in patients with histiocytic neoplasms as compared with the general population. We further found that CNS involvement was independently associated with worse HRQoL, regardless of the diagnosis type. Additionally, female sex was associated with worse MH scores, and bone involvement with worse PH scores. PROPr score was particularly low among patients with ECD. Future research is warranted to assess the impact of treatments on HRQoL, as well as the economic loss resulting from loss of productivity as highlighted by low PROPr scores.

Background Complete blood count (CBC) is the most common hematology test performed. Reference limits, aka normal values, are known to vary from one hospital to another. However, little is known about the values of the upper (UL) and lower (LL) limits of common elements reported in the CBC and how they differ among facilities. The objectives of our study were to report the UL and LL of CBC elements from various hospitals in the US, analyze the variances, and describe their clinical significance. Methods This study was approved by the Mayo Clinic institutional review board. We obtained the reference limits of CBCs from various hospitals using the Epic electronic medical records Care Everywhere health information exchange. CBCs from 2020-2023 were included. We included the following CBC elements: hemoglobin (Hgb; male and female), mean cell volume (MCV), white blood cell count (WBC), and platelet count (PLT). We performed descriptive statistics and calculated the coefficients of variation (COVs). In addition, we analyzed the data for clinical context using: A) World Health Organization (WHO) major criterion for polycythemia vera of Hgb >16.5 g/dL and >16.0 g/dL for males and females, respectively; B) WHO major criterion for essential thrombocytosis of PLT >450 x109/L; and C) common textbook reference limits for MCV (80-100 fL) and WBC (5-10 x109/L). Results We collected CBC reference limits from 143 hospitals across 43 states and 99 cities. Most (54.5%) hospitals were community-based, while the rest (45.5%) were academic. The statistics are shown in the Table. In general, there was minimal variance in the UL and LL of CBC elements, with COVs mostly under 8.0%. The one exception was WBC LL, in which the COV was 10.5%. There was no significant difference in the CBC reference limits between academic and community hospitals. The median Hgb UL and LL for males were 17.5 (range, 16.3-18.1) and 13.5 (range, 12.0-14.3), respectively. Similarly, the median Hgb UL and LL for females were 15.7 g/dL (range, 14.6-16.3) and 12.0 g/dL (range, 11.0-12.5), respectively. Majority (93.5%) of the hospitals' male Hgb UL exceeded 16.5 g/dL. In contrast, only few (3.6%) of the hospitals' female Hgb UL exceeded 16.0 g/dL (Figure A). The median MCV UL and LL were 99.0 fL (range, 92.2-103.0) and 80.0 fL (range, 77.0-88.0), respectively. A substantial minority (19.6%) of the hospitals' MCV UL exceeded 100 fL (Figure B). The median WBC UL and LL were 10.8 x109/L (range, 8.9-13.0) and 4.0 x109/L (range, 3.1-5.4), respectively. Most (80.4%) hospitals' WBC UL exceeded 10 x109/L (Figure C). The median PLT UL and LL were 400 x109/L (range, 317-500) and 150 x109/L (range, 125-172), respectively. Over a quarter (27.5%) of the hospitals' PLT UL were at or exceeded 450 x109/L (Figure D). Conclusions: There was minimal variance in CBC reference limits across hospitals in the US with WBC LL having the highest COV. Most MCV UL and WBC UL exceeded common textbook reference limits. Almost all male Hgb UL and over a quarter of PLT UL exceed the WHO major criteria of polycythemia vera and essential thrombocytosis, respectively. Since our findings suggest that there could be a risk of underdiagnosing these myeloproliferative neoplasms due to the commonly used reference limits, clinical context must be used when interpreting normal CBC results, especially when there is a suspicion of polycythemia vera or essential thrombocytosis.

Background Complete blood count (CBC) is the most common test performed in hematology-oncology. A typical CBC report contains over 10 elements. Simplifying the report by removing nonessential elements may benefit clinicians and patients. Little is known about what elements are reported by various hospitals in the US. The objective of our study was to describe how hospitals in the US report CBC. Methods After approval from the Mayo Clinic institutional review board, we obtained hospital CBC reported elements from the Epic electronic medical records Care Everywhere health information exchange. CBCs from 2020-2023 were included. For each hospital, we determined the city and state where it's located. We obtained the number and type of elements reported in the CBC and compared the findings between academic and community hospitals. Results We collected CBC data from 139 hospitals across 43 states and 102 cities (Figure 1). Fifty-four percent were community hospitals while 46% were academic hospitals. The median number of elements reported by all hospitals was 21 (range, 12-24). This was not different (P=0.98) between academic (median 22 [range, 12-24]) and community hospitals (median 21 [range, 14-24]; Figure 2). The distribution of hospitals according to the number of CBC elements reported were as follows: 12-15 (6%), 16-19 (13%), 20 (25%), 21(6%), 22 (18%), 23 (19%), and 24 (13%). A minority of the hospitals did not report % white blood cell differential count (9.4%) or mean platelet volume (20.9%). Nucleated red blood cell and immature granulocyte count were reported frequently, 46.0% and 56.8%, respectively. However, the frequency of reporting these four elements were similar between academic and community hospitals. Conclusions We found substantial variations in CBC reporting among US hospitals even within academic and community hospitals. Most hospitals reported 20 or more elements, twice as many as the hospitals reporting the least number of elements. There is an opportunity to simplify and standardize CBC reporting, which will minimize physician burnout and distraction as well as decrease patient concern and query.

Introduction Lymphoid malignancy (LM) is a heterogenous neoplasm with respect to biology, aggressiveness, and treatment with over 100 subtypes, including Hodgkin lymphoma (HL), non-Hodgkin lymphoma (NHL), and multiple myeloma (MM). Genome-wide association studies have identified common variants associated with risk of specific LM subtypes, but less is known about the contribution of rare inherited pathogenic variants (PV) in the genetic architecture of LM risk. Rare PV have been shown to contribute to the genetic architecture of solid tumor cancer risk, many of which have been found in genes that are important to the DNA-damage repair (DDR) pathway (e.g., BRCA1, BRCA1, ATM). Here, we investigated the prevalence of PV in cancer predisposition genes regularly included on multi-gene panel testing based on NCCN guidelines and correlated with risk of LM overall and by common subtypes. Methods In this association study, cases were newly diagnosed lymphomas (excluding chronic lymphocytic leukemia) from Mayo Clinic who were enrolled between 2002 and 2015 in the Lymphoma SPORE Molecular Epidemiology Resource (MER) and MM from Mayo Clinic enrolled primarily between 1998 and 2022 in a clinical registry. Controls were from the Mayo Clinic Biobank who were enrolled between 2009 and 2016, from which we excluded individuals with a history of hematologic malignancy. All participants provided a blood sample for whole exome sequencing, performed by Regeneron on an Illumina NovaSeq panel (mean coverage of 48X). Variants were called using GATK v4 and variant annotation was performed using BioR. All loss-of-function variants (i.e., nonsense, frameshift, and consensus splice sites) and pathogenic missense in 19 cancer predisposition genes with a minor allele frequency < 0.5% were included in the analyses. Logistic regression was used to estimate odds ratio (OR) and 95% confidence intervals (CI) for the association between mutation status by gene (burden test) and risk of LM overall, and by subtype that had more than 5 mutation carriers. All analyses were adjusted for age (at diagnosis for cases and at enrollment for controls) and sex. Results A total of 6990 cases and 42432 controls were included. Median age was 63 years for both cases and controls (case range 18-94 years, control range 18-99 years). Males accounted for 58.5% (n=4090) of the cases and 41.7% (n=17762) of the controls. MM accounted for 31% (n=2138) of the cases, followed by diffuse large B-cell lymphoma (DLBCL, n=1146) and follicular lymphoma (FL, n=1132) each accounting for 16% of cases. CHEK2 (1.0%), ATM (0.4%), BRCA2 (0.4%), and BRCA1 (0.3%) had the most PV carriers in controls; these frequencies are in the range of published control populations. A total of 1816 (3.7%) individuals had a PV across the 19 genes, with 4.7% of cases and 3.5% of controls carrying any PV (OR=1.34, 95% CI: 1.18-1.51). ATM (OR=1.86, 95% CI: 1.36-2.49), CHEK2 (OR=1.74, 95% CI: 1.42-2.13) and TP53 (OR=9.07, 95% CI: 4.51-18.87) were all significantly associated with increased risk of LM overall (Figure 1). When investigating subtypes (Table 1), CHEK2 (OR=1.93, 95% CI: 1.23-2.89) and TP53(OR=10.97, 95% CI: 3.06-31.43) were significantly associated with DLBCL. ATM (OR=2.22, 95% CI: 1.13-3.90) was significantly associated with FL. ATM (OR=1.97, 95% CI: 1.16-3.12), CHEK2 (OR=1.75, 95% CI: 1.24-2.41) and TP53 (OR=7.67, 95% CI: 2.43-20.72) were significantly associated with MM and ATM (OR=8.62, 95% CI: 4.47-15.12), NBN (OR=6.94, 95% CI: 2.41-15.76) and TP53 (OR=38.30, 95% CI: 10.27-116.69) were significantly associated with mantle cell lymphoma (MCL). When subset to LM cases overall, there was no evidence of enrichment for young onset (age <60 years), male sex, or family history of hematologic malignancy between PV carriers and non-PV carriers. However, FL cases with an ATM PV tended to be less than 60 years (OR=3.21, P=0.09) compared to non- ATM PV carriers. Similarly, MM cases with a TP53 PV tended to be less than 60 years of age (OR=7.39, P=0.07) compared non-carriers. Discussion In this large case-control study, PV in established cancer predisposition genes were associated with increased risk of LM overall, demonstrating that rare inherited variants may play an important etiologic role. This study also suggests that PV in cancer predisposition genes may be subtype specific. These results will help inform LM risk for individuals who undergo genetic testing of cancer predisposition genes.

Background: Warm autoimmune hemolytic anemia (WAIHA) is mostly IgG mediated (IgG+C3-), which may at times fix complement (IgG+C3+). Whether the clinical outcome of complement-fixing (C3+) WAIHA is different from that of non-complement fixing (C3-) WAIHA remains unclear. The goal of this retrospective study was to describe and compare the clinical characteristics and treatment outcomes of patients with C3+ and C3- WAIHA. Methods: We included adult WAIHA patients seen at our institution from 2001-2023 who met all of the following criteria: A) age >18 years; B) direct antiglobulin test [DAT] IgG+ + C3+ with no cold agglutinin; and C) biochemical evidence of hemolysis. Response to treatment was based on the international consensus criteria: complete (CR; normal Hb or Hb ≥12 g/dL, with resolution of hemolysis); partial (PR; Hb >10 but <12 g/dL or Hgb >12 g/dL without resolution of hemolysis); or no response (neither CR nor PR). 223 WAIHA patients were found, and 132 patients were ultimately included. The most common reason for exclusion was a lack of complete DAT that included C3 testing. Results: There were 59 patients with C3- WAIHA and 73 patients with C3+ WAIHA, reflecting 44.7% and 55.3% of total patients respectively. Pertinent demographic, clinical, and treatment information are shown in Table 1. Slightly over half (52.3%) were males and the mean age (SD) was 63.9 years (18.1). Concomitant lymphoproliferative disease was present in 34.1% of the patients. The 3 most common treatments were steroids (97%), rituximab (66.7%), and splenectomy (18.2%). The median follow-up from diagnosis was 20.0 months (range, 1.0-251.8 months), and 14.4% of patients had died at the time of this analysis with no difference between the groups (P=0.82). There was no significant difference in the demographic composition, clinical findings, and treatment received in both groups. The number of treatments received were similar between C3- and C3+ WAIHA groups (Table 1). After first line of treatment, response was achieved in 86.4% and 94.4% of the C3- and C3+ groups (P=0.12), respectively. Additionally, 62.7% of the C3- group and 80.8% of the C3+ group were in PR or CR by their most recent CBC (P=0.02). 33.9% and 43.8% of the C3- and C3+ groups relapsed at least once (P=0.25). In those who relapsed, there was an average of 2.6 relapse events in the C3- WAIHA group compared to 1.8 relapse events in the C3+ WAIHA group (P=0.03). However, there was no difference in time to first relapse between the groups (P=0.51), shown in Figure 1. Conclusion: There have been retrospective descriptions of multiple AIHA subtypes and response rates to different therapies; however, this is one of the first studies to our knowledge to focus specifically on outcomes between complement subgroups. In our large group of patients with C3- and C3+ WAIHA, the clinical presentation, treatments utilized, and response to treatment were similar. Our data suggest that C3- and C3+ WAIHA can be approached and treated similarly.

Metastatic CUP is complex, especially NCUP. Precision oncology is crucial for rare, aggressive cancers. A 54-year-old had HER2+ neuroendocrine carcinoma of unknown origin. T-DXd treatment, response, re-challenge show importance of genomics and caution.

191 Background: ANC is used to determine the dosing of chemotherapy and eligibility in clinical trials. Duffy-null phenotype is associated with a lower ANC and present in 2/3 of the Black population. Therefore, ANC reference intervals from hospitals serving a larger percentage (%) of Black population are expected to be lower. Ideally, reference intervals should represent the normal values of the population served. The objective of this study is to determine if the ANC reference intervals of hospitals in the US are representative of the population served based on racial diversity. Methods: We obtained hospital ANC reference intervals from the Mayo Clinic EPIC electronic medical records Care Everywhere health information exchange. Reference intervals from 2020-2023 were included. For each hospital, we determined the city where it is located. For each city, the % of Black population was obtained from the 2020 US Census. We studied the correlation (Pearson) between reference ANC values and % of Black population. To determine the expected ANC reference intervals, we obtained ANC data from the 2021-2022 National Health and Nutrition Examination Survey (NHANES) and performed a reference interval simulation study. Individuals with cancer and cirrhosis were excluded. Random samples of 120 individuals were selected, consisting of n samples from Black individuals and 120-n samples from non-Black individuals. This was performed for n from 0 to 120, and repeated 1000 times per n. Results: We collected data from 107 hospitals across 40 states and 81 cities. Fifty-three (49.5%) hospitals were academic. The % of Black populations in the cities served by the hospitals was a mean of 23.4% (range, 0.7%-82.8%). There was no correlation between ANC upper (r = -0.17, p=0.07) and lower (r = 0.01, p=0.88) limits based on the % Black population. This finding was similar in both academic and non-academic hospitals. Assessment of the ANC distribution in the US population based on race by using the NHANES database showed a clear association with race at the 2.5th (p<0.001) and 97.5th (p=0.009) percentiles with an overall estimated mid-95% reference range of 2.0-8.3 for non-Black individuals and 1.3-7.7 for Black individuals. Conclusions: Hospitals serving a higher % of Black population have similar upper and lower ANC reference intervals compared to those serving a lower % of Black population. This contrasts with the findings from NHANES data which showed significant variations in the normal ANC values between Black and non-Black individuals. Therefore, current hospital ANC reference intervals may not represent the diversity of the population served. Potential clinical implications include misdiagnosis of neutropenia, delay or underdosing of chemotherapy, and inappropriate exclusion in clinical trials, especially in areas with a high % of Black population.

101 Background: In the US, minority patients are underrepresented in cancer clinical trials. This is due to multiple factors, including socioeconomic barriers, limited medical insurance coverage and restrictive clinical trial eligibility, e.g., ANC cutoff. For the latter, conservative ANC cutoff disadvantages Black patients. Two-in-three Black individuals have a Duffy-null phenotype, that is associated with lower ANC with 5% prevalence of ANC <1,500 cells/µl. To improve Black patient accrual to cancer clinical trials, lowering the ANC cutoff was proposed as a potential solution over a decade ago. Its implementation is not known. This study evaluates the ANC cutoff values as part of the eligibility criteria for cancer clinical trials. Methods: We accessed the Clinicaltrials.gov website on 5/25/2023 and obtained the ANC cutoff of cancer clinical trials conducted in the US. We included adult therapeutic trials in the phases of recruiting, not yet recruiting, enrolling by invitation, and active-not yet recruiting. Trials with drug interventions were selected. Those focusing on surgical, behavioral, nutritional and radiotherapeutic interventions were excluded. All ANC cutoff values were converted to “cells/µl” for analysis. Results: A total of 911 trials were evaluated, and 470 met the eligibility criteria. Of the 470 trials, 366 (78%) involved solid malignancies, and 104 (22%) involved hematologic malignancies. Hematologic trials have significantly lower ANC cutoffs compared to solid tumor trials with median ANC cutoff of 1,000 (range, 250-2000) vs. 1,500 (range 250-3,000); p=<0.001. In all, 323 trials (68.7%) required patients to have ANC >1,500, and 116 trials (24.6%), primarily hematologic, required patients to have ANC >1,000. For myeloma and prostate cancer, two cancers with higher incidence among Blacks, 12.9% and 86.4% of the trials require ANC >1,500, respectively. All genitourinary, breast, head & neck, sarcoma, lung, skin, and neuroendocrine tumor trials excluded patients with ANC <1,000. Conclusions: Most hematologic malignancy trials have a more liberal ANC cutoff allowing patients with ANC <1,500 to participate. However, solid tumor trials remain more conservative, with 4 in 5 trials requiring an ANC cutoff of >1,500. A strict ANC cutoff remains a barrier to minority accrual.[Table: see text]