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Objective: The purpose of this study is to increase awareness and improve diagnosis of primary immune deficiency (PID) in the heterogenous group of patients with autoimmune cytopenia (AIC) by identifying clinical characteristics and laboratory biomarkers that distinguish PID patients from patients with AIC alone. This is especially relevant in genetically-defined PIDs which may be resistant to conventional therapy and mechanism-based treatment approach is required. Evans syndrome, defined by multi-lineage autoantibodies (two or more positive anti-platelet, anti-neutrophil, or direct Coombs test) is a known risk factor for PID; therefore we also investigate the incidence of PID in a broad cohort of AIC patients with single and multi-lineage cytopenias. Methods: Patients with autoimmune cytopenias (autoimmune hemolytic anemia (AIHA), immune thrombocytopenia (ITP), or autoimmune neutropenia (AIN)) were referred to our Immune Dysregulation clinical team and prospectively enrolled in the study period of 2016-2019. Detailed immune phenotyping (IgG, IgA, IgM, lymphocyte subsets, vaccine titers, lymphocyte proliferation to mitogens/antigens), serum lipopolysaccharide (LPS) and autoantibodies were measured and/or collected by chart review and genetic testing for PID was pursued. Results: From 2016 to 2019, 78 patients were enrolled to our study. The patients were predominantly children (ages 1-82 years, average age 16.82 years). Of 78 patients with AIC, 48 (61%) were diagnosed with underlying PID based on immune phenotyping and/or genetic testing. Of 39 patients with genetic testing to date, 19 (49%) have been diagnosed with genetically-defined PID (pathogenic variants in CTLA-4, NFKB1, ALPS-related genes, WAS, POLE-1, PI3K, CYBB, or 22q11 [partial DiGeorge syndrome]); the remainder were classified as combined immune deficiency or common variable immune deficiency based on immune phenotyping; an additional two patients were classified as ALPS based on clinical history/flow cytometry/family history of ALPS. Lymphocyte subsets (CD4+ T, CD8+ T, CD19+ B, CD56+ NK) and immune globulins (IgG, IgA, IgM) tended to be lower in AIC-PID patients vs AIC-only (p Conclusions: An unexpectedly high fraction of patients with AIC were identified with underlying PID in our Immune Dysregulation program. Routine basic immune evaluation with immunoglobulin levels and lymphocyte subsets expedited diagnosis of PID. Genetic evaluation distinguished a group of patients with AIC-PID and highly elevated LPS level, reflecting high bacterial load, and this may distinguish them from the rest of patients with AIC. The source of bacterial LPS can be multifactorial and is yet to be determined. Our studies continue focusing on biomarkers that can be applied to the heterogenous group of patients with AIC. This will allow early detection and timely initiation of targeted therapies. Disclosures No relevant conflicts of interest to declare.

Background: Renal medullary carcinoma (RMC) is a rare, aggressive form of renal cell carcinoma almost exclusively (>90%) diagnosed in individuals with sickle cell trait (SCT), and 2/3 of those affected are male. Based on population-surveillance data, only 246 patients were diagnosed with RMC between 2005-2014 (Carden etal. J Sickle Cell Disease and Hemoglobinopathies, 2018) and many patients have metastatic disease at diagnosis (Msaeoul et al., Clin Genitourin Cancer, 2019). Median overall survival (OS) in patients with metastatic RMC (mRMC) at diagnosis is less than 12 months and predictors of survival are largely unknown, although case reports suggest novel chemotherapeutic strategies are important (Carden et al., Ped Blood Cancer, 2017&2018). The role SCT plays in RMC pathobiology, however, is largely unknown, as many patients do not have a complete hemoglobin subtype profile completed at diagnosis. Studies evaluating sickle hemoglobin concentrations (%HbS) in relation to survival for patients with RMC are needed, as SCT is associated with renal dysfunction and researchers have hypothesized that HbS polymerization within red cells traversing the kidney disrupts blood perfusion, which leads to kidney injury and an increased possibility for cancer formation (Msaeoul et al, Clin Cancer Res, 2018). Patients with %HbS≤36%, such as patients with SCT and concomitant alpha-globin gene deletion(s) might be protected against HbS polymerization and renal concentrating defects (Gupta etal., J Clin Invest, 1991). We hypothesize that lower %HbS is associated with higher survival. In this preliminary multi-institutional study, we retrospectively reviewed available charts from patients diagnosed with mRMC and SCT to evaluate for an association between %HbS and OS. Methods: We found nine patients (3 adults, 6 children) who were diagnosed with mRMC and SCT at our various institutions between 2002-2017 who had survival data. Eight patients had %HbS levels by hemoglobin quantification at diagnosis. In a post-hoc analysis, patients were separated into two groups (%HbS>36% and %HbS≤36%), levels similar to that found in patients with alpha-globin gene deletions described by Gupta et al. Fit-curves were determined for OS vs. %HbS. Three-year OS was determined using Kaplan-Meier analysis and the log-rank method. P Results: Clinical characteristics of patients are shown in Table 1. Average age (standard deviation) at diagnosis was 15.2 years (4.9) and most patients were male (87.5%). Six patients had %HbS >36% and 2 patients had %HbS ≤36%. Median OS was 17.8 months. Using fit-function testing, analysis of survival vs. %HbS yielded an exponential relationship (R2=0.69), suggesting higher survival when %HbS≤36% (p=0.05). OS of the two patients with %HbS≤36% was greater than those with %HbS>36%, though results were not statistically significant (p = 0.09). Conclusion: While there are limitations to this small, retrospective analysis, these data suggest that lower intracellular red cell %HbS concentrations could be protective in patients with mRMC and SCT. Chemotherapy and other treatment regimens may also play a role in survival and need to be studied. Further investigation is needed to determine the role SCT plays in RMC pathobiology and to determine if %HbS concentrations, as well as alpha-thalassemia deletion(s), may be protective in patients with RMC. Disclosures Carden: GBT: Honoraria; NIH: Research Funding.