Warm Autoimmune Hemolytic Anemia Research Articles

Challenges in the diagnosis and management of autoimmune hemolytic anemia: A case-based approach. Experience from a tertiary care hospital in the Haryana region.

Autoimmune hemolytic anemia (AIHA) is a rare immune disorder which occurs when antibodies are directed against self red blood cells (RBCs) leading to hemolysis. AIHA is widely classified as warm autoimmune hemolytic anemia, cold agglutinin syndrome, mixed AIHA, paroxysmal cold hemoglobinuria and rarely drug induced AIHA. The pathogenesis of AIHA is complex interplay between genetic predisposition, immune dysregulation and enviornmental triggers. A direct antiglobulin test can be used to assess the immunological origin of the hemolysis in order to diagnose AIHA after identifying laboratory and clinical symptoms of hemolysis. The objective is to understand underlying mechanism in AIHAs, and usage of targeted therapies to modulate specific components of the immune response. We are hereby presenting a case series of 11 clinically suspected cases of AIHA in collaboration with their clinical features, immuno-hematological and other laboratory parameters, Flow cytometric analysis of lymphocyte subset in relevant cases, underlying etiology as well as serological subtype are also included. Majority of the patients were categorized as secondary AIHA (7/11, 63.63%). Out of 11 cases 7 were serologically subtyped as warm AIHA (7/11, 63.63%) ,2 cases were DaaT negative AIHA (2/11;18.18%), 2 cases were characterized as mixed AIHA subtype (2/11, 18.18%). Accurate subtyping of AIHA requires a systematic immunohematological approach coupled with comprehensive evaluations of clinical, hematological, and biochemical parameters.

Severe, Refractory Primary Warm Autoimmune Hemolytic Anemia Requiring 90 Erythrocyte Transfusions.

A previously healthy 60-year-old man presented to the hospital with a hemoglobin of 3.5 g/dL. He was diagnosed with severe warm autoimmune hemolytic anemia (wAIHA) with reticulocytopenia on hospital day 1 that was not responsive to steroids, immune globulin, and rituximab. Over a 42-day hospital stay, the patient remained continuously transfusion-dependent with a ninety red cell unit requirement for his refractory disease. He was trialed on therapeutic plasma exchange before ultimately undergoing inpatient splenectomy that led to a response within hours. He remains in complete remission at six months of follow-up.

Efficacy and Safety of Weekly Bortezomib-dexamethasone as the Third-Line Therapy for Warm Autoimmune Hemolytic Anemia: a Case Series of 5 Patients

Efficacy and Safety of Weekly Bortezomib-dexamethasone as the Third-Line Therapy for Warm Autoimmune Hemolytic Anemia: a Case Series of 5 Patients

Autoimmune Hemolytic Anemia: A Review

Autoimmune hemolytic anemia (AIHA) is defined as an anemia caused by the destruction of red blood cells by antibodies directed against the patient's own red blood cell surface antigens. Different forms of AIHA are distinguished based on the characteristics of the antibody responsible for the disease. The most common form (70% of cases) is warm antibody autoimmune hemolytic anemia. These antibodies become active at temperatures between 35°C and 40°C. This type of hemolysis occurs mainly within tissues, particularly in the spleen. The diagnosis of AIHA relies on rigorous interpretation of immunohematological parameters, as well as additional tests to exclude associated diseases. In "idiopathic" cases, it is recommended to continue monitoring elderly patients beyond remission to detect the possible occurrence of lymphoma or myelodysplastic syndrome. Corticosteroid therapy is the standard treatment, but it can lead to numerous side effects. The efficacy of rituximab appears particularly promising in "refractory" forms of AIHA, and its use in the early phase of management to spare corticosteroid therapy should be evaluated in a prospective and randomized study.

Healthcare resource utilization of patients with warm autoimmune hemolytic anemia initiating first line therapy of oral corticosteroids with or without rituximab.

This retrospective cohort study described real-world treatment patterns and healthcare resource utilization (HCRU) of patients with warm autoimmune hemolytic anemia (wAIHA) initiating treatment with first-line (1L) oral corticosteroids (OCS) + rituximab (R) compared to 1L OCS. Patients with a wAIHA diagnosis code (D59.11) between 8/2020-3/2022 were identified using US pharmacy and medical claims databases. Patients initiating 1L OCS ± R were identified (date of initiation = 'index date') with a 1-year pre-index period and a variable (minimum 1-year) follow-up period. The final sample comprised 77 1L OCS + R patients and 400 1L OCS patients (~ 60% female, mean age > 64 years). Over the 1-year follow-up, HCRU was higher in the OCS + R cohort with higher mean number of physician office visits (22.9 and 14.4; p < 0.01), including hematology/oncology office visits, and higher utilization of rescue therapy (59.7% and 33.3%; p < 0.01), driven by higher use of injectable corticosteroids. Patients in OCS + R and OCS groups completed 1L therapy after a similar mean duration of 103.5 and 134.6 days, respectively (p = 0.24). In the majority of patients, second-line (2L) therapy was initiated at a similar timepoint: 66.2% OCS + R and 72.0% OCS cohorts (p = 0.31) initiated 2L in a mean of 218.3 and 203.2 days (p = 0.76) after the end of 1L treatment, respectively. The addition of rituximab in 1L did not extend the remission period, with most patients in both cohorts initiating 2L therapy within less than 1 year of completing 1L treatment. 1L OCS + R patients also had substantial HCRU burden. More effective novel therapies are needed to address the high unmet need in wAIHA.

Warm Autoimmune Hemolytic Anemia with Chronic Hepatitis B

Introduction: Warm autoimmune hemolytic anemia (wAIHA) is caused by erithrocytes destruction by IgG or IgG plus C3d-mediated autoantibody. Long use steroids are first line therapy of wAIHA. It has risk infection reactivation, like chronic hepatitis B. Case report: Man, 64 y.o, hospitalized with diagnosis wAIHA and chronic hepatitis B. Diagnosis of wAIHA is built by: severe normocytic normochromic anemia, reticulocytosis 42.29%, increasing lactate dehydrogenase 397 U/L, direct Coombs test (+4), antibody screening IgG (+4). Anothers laboratorium findings: HbsAg (+), albumin 3.5 g/dL, ALT U/L, rapid HIV (-), anti HCV (-). There is no blast found in peripheral blood and bone marrow smear. Patient also diagnosed chronic hepatitis B inactive phase with negative HbeAg, HBV DNA 547 IU/L, normal liver finding in abdominal USG and moderate fibrosis from fibroscan. Washed red cell transfussion was administered, 2 x 125 mg methilprednisolone iv (3 days) tapering off until to 40 mg/day doses. He did not get antiviral prophylaxis and be planned to reevaluate in next 6 months. Conclusion: Steroid is first line therapy in wAIHA. When wAIHA is diagnosed, determination of chronic hepatitis B status should confirmed. There is a risk of reactivation of chronic hepatitis B infection so monitoring is needed.

Cold agglutinin disease: pathology, diagnosis, and treatment

Cold agglutinin disease (CAD), an immune hemolytic disease mediated by the classical complement-dependent pathway, accounts for approximately 8% of autoimmune hemolytic anemia (AIHA) cases. Primary CAD is a clonal B-cell lymphoproliferative disease of the bone marrow that produces IgM type-M protein, while conventional secondary CAD is cold agglutinin syndrome (CAS). Clinical findings are broadly classified into chronic anemia due to hemolysis and symptoms associated with peripheral circulatory failure due to erythrocyte aggregation under cold exposure. Not all patients require drug therapy, but monoclonal antibody therapy against complement C1s is preferred for the former presentation and B-cell suppressors for the latter. As cold AIHA is treated differently than warm AIHA, misdiagnosis can significantly impact the outcome of treatment. The most important aspect of blood testing is temperature control of specimens. Cold agglutinin titer, IgM quantification, electrophoresis, and immunofixation methods may produce false-negative results if the serum is not temperature-controlled at 37-38°C until serum separation. Correct handling of specimens, along with knowledge of the various clinical features of CAD, will lead to correct diagnosis and appropriate treatment.

C3+ and C3- Warm Autoimmune Hemolytic Anemias: A Comparison of Clinical Characteristics and Treatment Outcomes

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 &amp;gt;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 &amp;gt;10 but &amp;lt;12 g/dL or Hgb &amp;gt;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.

A Phase III Clinical Trial Program Investigating the Efficacy and Safety of Ianalumab in Patients with Primary Immune Thrombocytopenia (VAYHIT1 and VAYHIT2) and Warm Autoimmune Hemolytic Anemia (VAYHIA)

Background: Immune thrombocytopenia (ITP) and warm autoimmune hemolytic anemia (wAIHA) are characterized by autoantibody destruction of platelets and red blood cells, respectively. Autoreactive B cells play a role in the pathophysiology of ITP and wAIHA. Serum levels of B-cell activating factor (BAFF) are elevated in these disorders and correlate with increased disease activity. Ianalumab is a novel, fully human immunoglobulin G1 monoclonal antibody that targets BAFF receptor (BAFF-R) and has a unique dual mechanism of action: direct antibody-dependent cellular cytotoxicity-mediated B-cell depletion and inhibition of B-cell differentiation, proliferation and survival via blockade of BAFF-R-mediated signaling. Corticosteroids (CS) are the standard first-line treatment for ITP; however, few patients achieve a long-term response. Additionally, extended and recurrent use of CS is associated with substantial toxicity. Thrombopoietin receptor agonists (TPO-RAs), such as eltrombopag, are commonly used second-line ITP treatments and often achieve a response; however, responses are rarely maintained once treatment ends, so chronic administration is typically required. For wAIHA, few treatments have been approved, and patients rarely achieve durable responses on CS or off-label rituximab. Thus, there are significant unmet needs for patients with ITP or wAIHA. Aim: We report the designs of the randomized, double-blind, multicenter, 3-arm Phase III VAYHIT1 (NCT05653349), VAYHIT2 (NCT05653219) and VAYHIA (NCT05648968) trials. The trials aim to assess whether ianalumab, working with a distinct and complementary mechanism to standard-of-care treatments, can induce durable responses in patients with ITP or wAIHA. Trial designs: VAYHIT1 and VAYHIT2 will assess the efficacy and safety of ianalumab vs placebo in addition to first-line CS and short-term eltrombopag, respectively, in adults with primary ITP. In both trials, patients will be randomized 1:1:1 to intravenous (IV) low-dose ianalumab, high-dose ianalumab or placebo every 4 weeks (wks). The primary endpoint in both trials is the time from randomization to treatment failure, defined as platelet count &amp;lt;30 G/L later than 8 wks from randomization, need for rescue treatment later than 8 wks from randomization, start of a new ITP therapy, or death. In VAYHIT2, ineligibility to taper or inability to discontinue eltrombopag after the completion of treatment with ianalumab or placebo will also be assessed as treatment failure. Secondary endpoints include response rate, complete response rate and safety ( Table). VAYHIA will assess the efficacy and safety of ianalumab vs placebo in adults with wAIHA who have failed ≥1 treatment. Patients will be randomized 1:1:1 to IV low-dose ianalumab, high-dose ianalumab or placebo every 4 wks. Selected supportive care is allowed. The primary endpoint is durable hemoglobin (Hb) response, defined as Hb ≥10 g/dL and an Hb increase of ≥2 g/dL from baseline for ≥8 consecutive wks between Wk 9 and Wk 25 in the absence of rescue or prohibited treatment. The key secondary endpoint is duration of durable Hb response ( Table). An optional open-label crossover period will allow patients who receive placebo and do not achieve a durable Hb response to receive high-dose ianalumab. Patients from all 3 trials will be monitored for efficacy until treatment failure (or up to 39 months after the last patient was randomized, whichever comes first) and safety for up to 2 years. Conclusions: These trials have been designed based on the hypothesis that, when administered early in disease progression, medical therapy targeting complementary physiological pathways may restore self-tolerance in patients with ITP and wAIHA. Ianalumab in combination with standard of care is expected to safely induce a high response rate that will be maintained beyond treatment completion. Ianalumab may address the unmet needs for patients with ITP and wAIHA. Current status: At the time of writing, VAYHIT1, VAYHIT2 and VAYHIA are recruiting. The open-label, single-arm, Phase II VAYHIT3 trial is also assessing ianalumab in patients with primary ITP previously treated with at least 1 CS and 1 TPO-RA (NCT05885555).

Whole Exome Sequencing of Patients with Adult-Onset Evans Syndrome: A Cohort of 80 Patients

Introduction Loss of tolerance toward several self-antigens suggests an underlying genetic predisposition. A previous study (1) conducted in children with Evans syndrome revealed a high prevalence of pathogenic mutations in genes involved in primary immunodeficiencies. Whether these findings are restricted to children is unknown. In this study, we assessed the prevalence of constitutional genetic variants in a cohort of patients with adult onset Evans syndrome. Patients and methods We consecutively included from November 2021 to June 2023 patients that had been diagnosed with adult onset (≥18 years) Evans syndrome (association of immune thrombocytopenia (ITP), warm autoimmune hemolytic anemia (wAIHA) and/or autoimmune neutropenia (AIN) according to international guidelines (2,3)), and identified in France throughout the network of the national reference center for adult' autoimmune cytopenia. We excluded patients with a systemic lupus (according to Systemic Lupus International Collaborating Clinics criteria (4)), and patients with indolent B cell malignancies at Evans syndrome onset. Clinical and biological data were retrospectively collected using a standardized form. Patients underwent whole-exome sequencing after written and informed consent was obtained. Gene variants already published and/or with in vitro confirmed consequences were considered as genetic diagnoses. Clinical interpretation of variants was performed according to the ACMG guidelines (5). A patient was classified as having a genetic diagnosis if carryinghemizygous/heterozygous pathogenic or likely pathogenic variant (for X-linked or autosomal dominant conditions), or 2 pathogenic or likely pathogenic variants in the same gene (for autosomal recessive conditions). Results We identified 80 patients (40% female, median age 31 years at Evans syndrome diagnosis [range 18-76]) with adult-onset Evans syndrome from 19 centers. Median age at first cytopenia was 28 years [range 1-73], and 13 patients (16%) were under 18 years at first cytopenia. 78 patients (96%) had ITP (chronic in 87%), 59 (73%) had wAIHA (with at least one relapse in 58%), and 38 (47%) had AIN (chronic in 74%). Median delay between first and second cytopenia was 18 months (range 0 - 329) and 28 patients (35%) had synchronous onset of cytopenia. Twenty-four patients (30%) had associated immune manifestation (involving endocrine system in 9%, lung in 9%, gastrointestinal tract in 6%, skin in 5%, central nervous system in 4%) and 28% had antinuclear antibody titers ≥ 1/160. Lymphoproliferation was found in 56%, including lymphadenopathy in 41% and splenomegaly in 35%. Nine patients (11%) had lymphoma or cancer history. Twenty patients (25%) had humoral immune defect, including 13 (16%) with a common variable immunodeficiency (CVID)-like phenotype. In the whole cohort, 9 patients (11.25%) had a genetic diagnosis that could be linked to Evans syndrome, with heterozygous variants in CTLA4, STAT3, NFKB1, CYBB, TNFAIP3, DDX41, MYH9 and homozygous variant in PIK3CG. Twenty (25%) patients had genetic testing prior to this study (targeted Sanger sequencing [N=3], or NGS panel [N=17]), resulting in 2 genetic diagnoses ( CYBB and TNFAIP3). A family history of immune manifestations in first-degree relatives was found in 56% of the patients with genetic diagnosis versus 20% of patients without (P=0.0308). However, the proportion of patients with CVID-like phenotype, associated immune disorder, lymphoproliferation, cancer/lymphoma, positive antinuclear antibodies, or pediatric onset of first cytopenia was not significantly increased in patients with genetic diagnosis. Discussion As expected, the proportion of genetic diagnoses in patients with adult onset Evans syndrome was lower that what was previously described in children, but led to a significant impact on clinical management in some patients. We did not find clinical or biological features associated with a genetic diagnosis, suggesting that genetic testing should be considered in every adult patient diagnosed with Evans syndrome in the absence of any obvious underlying cause or condition. References (1) Hadjadj J et al., Blood 2019; 134: 9-21. (2) Provan D et al., Blood Adv 2019; 3: 3780-817. (3) Jäger U et al., Blood Rev 2020; 41: 100648. (4) Petri M et al., Arthritis Rheum 2012; 64: 2677-86. (5) Richards S et al., Genet Med 2015; 17: 405-24.

Ianalumab, a Novel Anti-B-Cell Activating Factor (BAFF) Receptor (BAFF-R) Monoclonal Antibody (mAb) in Development for Immune Thrombocytopenia (ITP) and Warm Autoimmune Hemolytic Anemia (wAIHA), Has Demonstrated a Favorable Safety Profile in Sjögren's Syndrome (SjS), Systemic Lupus Erythematosus (SLE) and Chronic Lymphocytic Leukemia (CLL)

Background: Current therapies for ITP and wAIHA are mostly symptomatic and rarely lead to durable responses after discontinuation; thus, chronic treatment is often needed, which may be associated with toxicity and substantial quality-of-life burden for patients. There is an unmet need for disease-modifying therapies that can induce and maintain durable responses beyond treatment completion in ITP and wAIHA. BAFF is an important regulator of B-cell differentiation, proliferation and survival through interactions with BAFF-R. Autoreactive B cells play a key role in the pathophysiology of ITP and wAIHA and are fueled by increased BAFF pathway activity; therefore, there is a strong rationale for investigating BAFF-R as a target in both diseases. Ianalumab is a fully human mAb that targets BAFF-R. It has a novel dual mechanism of action: blockade of BAFF-R-mediated signaling and potent depletion of B cells mediated by antibody-dependent cellular cytotoxicity. Ianalumab has shown favorable safety and encouraging efficacy in other indications, including SjS, SLE and CLL, and is a promising potential treatment for ITP and wAIHA. As ianalumab is being investigated in ongoing, blinded Phase III trials in ITP and wAIHA, we present the safety profile of ianalumab from completed Phase I/II studies in SjS, SLE or CLL. Methods: Data for patients with SjS were from a randomized Phase IIb trial (NCT02962895); patients (N=190) received subcutaneous (SC) placebo or ianalumab 5, 50 or 300 mg every 4 weeks (wks) for 24 wks. Patients then entered a second treatment period; patients in the ianalumab 5 or 50 mg arm continued the same dose, patients in the ianalumab 300 mg arm were randomized to continue the same dose or receive placebo, and patients in the placebo arm switched to ianalumab 150 mg. Safety data in patients with SLE were collected from a randomized Phase II trial (NCT03656562). Patients (N=67) received SC ianalumab 300 mg or placebo every 4 wks for 28 wks; patients in the placebo group could switch to ianalumab in a 20-wk open-label extension. Data for patients with CLL were from a Phase Ib trial (NCT03400176); patients (N=32) received intravenous (IV) ianalumab 0.3, 1, 3 or 9 mg/kg every 2 wks plus ibrutinib 420 mg once daily for up to 8 28-day cycles. Safety assessments included adverse events (AEs), serious AEs (SAEs) and AEs of special interest. Results: Ianalumab was safe and well tolerated in patients with SjS. Most AEs were mild or moderate in severity; severe AEs were reported in 5 patients receiving ianalumab. Three ianalumab-treated patients had SAEs; 2 SAEs in 1 patient (appendicitis and tubo-ovarian abscess) were considered related to ianalumab treatment. Frequency of infections/infestations was similar between patients treated with ianalumab and placebo. Discontinuation rates were low, with only 4 patients discontinuing ianalumab for non-serious AEs (infection [n=2], lymphopenia, local injection-site reaction [n=1 each]); no SAEs led to treatment discontinuation. Ianalumab continued to be well tolerated in the second treatment period. There were no dose-dependent differences in the rate of AEs except for injection-site reactions (mostly local and not severe). In ianalumab-treated patients with SLE, there were no serious infections during the blinded period; only 1 SAE (renal impairment) was reported. In the open-label extension, 4 SAEs were reported. No SAEs in the blinded period or open-label extension were considered treatment related. Most AEs in patients with CLL were Grade 1 or 2 and not correlated with dose. Twelve patients experienced Grade ≥3 AEs; decreased neutrophil count (n=5) was most common. No dose-limiting toxicities were reported. Discussion: Data from patients with SjS, SLE or CLL receiving ianalumab for up to 52 wks show it has a favorable safety profile. There was a low risk of infections irrespective of dosing regimen. No cases of hypogammaglobulinemia were clinically significant in any trial. New treatments are needed for ITP and wAIHA that have disease-modifying potential and allow patients to achieve and maintain high response rates after a short therapeutic course. Ianalumab has the potential to address this unmet need and is currently being assessed as an IV dose every 4 wks in Phase III trials as both a first- (VAYHIT1 [NCT05653349]) and second-line (VAYHIT2 [NCT05653219]) treatment for ITP and as a second-line treatment for wAIHA (VAYHIA [NCT05648968]).

Establishing Content Validity of the FACIT-Fatigue Scale in Patients Living with Warm Autoimmune Hemolytic Anemia: Results from Qualitative Interview Studies

Introduction: Warm autoimmune hemolytic anemia (wAIHA) is a rare, life-threatening autoimmune disorder caused by autoantibodies that bind to and prematurely destroy red blood cells. Patients with wAIHA can experience acute worsening of anemia which can be a medical emergency and have an increased risk of thromboembolic events and premature death. Fatigue is the primary patient-reported symptom for many individuals living with wAIHA. The patient-reported Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) scale is supported by robust psychometric evidence and has been used to support efficacy assessments of improvement in anemia-related fatigue. However, evidence of content validity of this scale has not been established in the wAIHA patient population. The objective of this research was to examine whether the FACIT-Fatigue is fit for purpose to assess wAIHA-related fatigue. Methods: Twenty hybrid concept elicitation/cognitive debriefing interviews were conducted with adults living with wAIHA across two sequential studies. All participants were recruited from the United States via research partners following IRB approval. The studies aimed to understand the symptoms and impacts of wAIHA on participants' daily lives with a specific focus on fatigue and to evaluate the FACIT-Fatigue scale in a wAIHA patient population. The last 10 interviews also included a qualitative evaluation of meaningful change on the FACIT-Fatigue individual items. Interviews were recorded and transcribed verbatim, and data were coded. Content and descriptive analysis methods were used to examine data at the item and participant level. Thematic analysis was conducted to identify emerging patterns across items and participants and to identify key constructs from concept elicitation. Results: Interview participants were primarily non-Hispanic white (n=16, 80%), female (n=11, 55%), and had a mean age of 47.5 ± 14.7 years. Fatigue was reported as a core symptom of wAIHA by all participants. Several participants noted that fatigue was their most bothersome symptom. Participants summarized the extensive impact fatigue had on their daily functioning, including reduced ability to work or volunteer, disruptions to their social lives, and negative changes to their emotional wellbeing. Cognitive debriefing affirmed that the instructions and items comprising the FACIT-Fatigue were well understood and relevant to their experiences with wAIHA, the 7-day timeframe was easy to recall, and participants were easily able to rate their experiences using the response scale (see Table 1 for item-level insights).The majority of participants who were asked about meaningful change identified a 1-point change as meaningful for each of the FACIT-Fatigue items. Analysis of participants' perspectives on meaningful changes at the item level indicated that a 3 point change in the total score would be meaningful for all participants. This aligns with previous studies that have published meaningful change thresholds of 3-6 points on the FACIT-Fatigue total score in populations with chronic conditions that cause fatigue. Conclusions: Fatigue is a debilitating symptom of wAIHA which impacts functioning across multiple domains. The content validity of the FACIT Fatigue scale is well supported by the results of the qualitative interviews as its items capture constructs that are relevant to evaluating fatigue and important to people living with wAIHA. These research findings support the use of the FACIT-Fatigue scale in clinical trials of treatments for wAIHA and suggest that a 3-point change of the total score would represent meaningful change in this patient population. Future work will focus on evaluating the psychometric properties of the FACIT-Fatigue scale in a wAIHA population.

Initial Report of Povetacicept, an Enhanced Dual BAFF/APRIL Antagonist, in Autoimmune Cytopenias: The RUBY-4 Study

Introduction: BAFF and APRIL are cytokines with key roles in B cell development, survival, differentiation into antibody-secreting cells (ASCs; plasmablasts and plasma cells), and production of antibodies, making them promising targets for the treatment of autoantibody-associated diseases such as immune thrombocytopenia (ITP), warm autoimmune hemolytic anemia (wAIHA), and cold agglutinin disease (CAD). Patients with ITP or AIHA have elevated serum BAFF and APRIL levels and belimumab, a BAFF inhibitor, has exhibited encouraging efficacy in the treatment of lupus-associated ITP as well as alone or in combination with rituximab for the treatment of primary ITP. Due to their overlapping but non-redundant roles, inhibition of both BAFF and APRIL may be required for optimal efficacy in autoimmune cytopenias. In preclinical studies, dual BAFF/APRIL inhibition achieved superior suppression of ASCs and immunoglobulin levels vs inhibitors of BAFF or APRIL alone or an anti-CD20 antibody, suggesting the potential of this novel mechanism to modify the underlying pathogenesis of autoimmune cytopenias. Povetacicept (ALPN-303) is a TACI-Fc fusion protein engineered for potent dual BAFF/APRIL inhibition. In a mouse model of AIHA, povetacicept suppressed anti-erythrocyte autoantibodies and increased hematocrit (ASH 2022 abstract #3763). In a first-in-human study in healthy volunteers, povetacicept was well tolerated and reduced levels of circulating ASCs and immunoglobulins. This is an initial report of an open-label study of povetacicept in autoimmune cytopenias (RUBY-4; NCT05757570). Methods: RUBY-4 is a phase 1b, group-sequential, parallel-cohort study evaluating povetacicept in participants aged ≥18 years with a documented diagnosis of primary ITP, wAIHA, or CAD of ≥12 weeks in duration (Figure). Eligible participants must have sustained thrombocytopenia (ITP cohort) or sustained symptomatic anemia (wAIHA/CAD cohorts)-i.e., platelet count &amp;lt;30 × 10 9/L or hemoglobin ≤10 g/dL on 2 occasions ≥7 days apart during screening-and a history of failure or relapse on ≥2 prior treatments (including a thrombopoietin receptor agonist for the ITP cohort). Background therapy, including corticosteroids, is allowed but must remain at stable doses for the durations specified in the protocol. Participants receive povetacicept 240 mg subcutaneously once every 4 weeks for 24 weeks, with an optional 24-week treatment extension, followed by an 8-week off-treatment follow-up period. The primary objective is safety and tolerability; secondary objectives include pharmacokinetics, pharmacodynamics, immunogenicity, and efficacy. Results: As of 31 July 2023, 1 participant with ITP has enrolled and received 2 doses of povetacicept 240 mg without incident. Initial, preliminary observations include expected reductions in B cells and immunoglobulin levels. The RUBY-4 study continues to enroll in the US, Canada, Australia, and Turkey. At the time of presentation, available data including safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy (e.g., platelet or hemoglobin response rate, duration of response, and time to response) findings will be reported. Conclusions: To our knowledge, povetacicept is the first dual BAFF/APRIL inhibitor to be evaluated for the treatment of autoimmune cytopenias. Previous preclinical and healthy volunteer studies suggest the potential of povetacicept for suppression of the pathogenic autoimmunity that mediates platelet/erythrocyte destruction in ITP, wAIHA, and CAD, which may lead to more durable responses and improved outcomes for patients.

Povetacicept (ALPN-303), a Potent Dual BAFF/APRIL Antagonist in Development for the Treatment of Autoimmune Cytopenias, Suppresses Disease in a Mouse Model of Autoimmune Hemolytic Anemia

Introduction: B cell activating factor (BAFF) and a proliferation inducing ligand (APRIL) play key roles in B cell development, survival, and differentiation into antibody-secreting cells (ASC). Given their importance in ASC survival and antibody production, inhibition of BAFF and/or APRIL (particularly in combination) is a promising approach for the treatment of a variety of autoimmune or autoantibody-related diseases including autoimmune cytopenias like warm autoimmune hemolytic anemia (wAIHA), immune thrombocytopenia (ITP), and cold agglutinin disease (CAD). Significantly higher levels of both BAFF and APRIL have been observed in the serum of patients with AIHA and ITP compared to healthy subjects, and polymorphisms in BAFF and TACI have been associated with ITP [Abdel-Hamid et al., Am J Med, 2011; Xu et al., Int J Hematol., 2015; Emmerich, et al., Br J Haematol, 2007; Peng, et al., J Thromb Haemost, 2017; Yu, et al., Blood Adv, 2021]. Belimumab, an anti-BAFF antibody, has demonstrated encouraging efficacy in the treatment of ITP associated with systemic lupus erythematosus [De Marchi, et al., Clin Exp Rheumatol, 2017] and in combination with rituximab in patients with ITP [Mahévas, et al., Haematologica, 2021]. Currently, there are no BAFF and/or APRIL inhibitors approved to treat AIHA or ITP. Povetacicept (ALPN-303) is an engineered, potent dual BAFF/APRIL antagonist. We previously evaluated the impact of BAFF/APRIL co-inhibition preclinically in the accelerated HODxOTII transgenic mouse model of AIHA, in which povetacicept treatment significantly suppressed plasma cells in the spleen and bone marrow, reduced pathogenic anti-RBC autoantibodies, and significantly increased hematocrit [Dillon et al., ASH 2022 abstract #3763]. Here, we have evaluated povetacicept in a second preclinical model of AIHA, a rat red blood cell (RRBC)-to-mouse model of erythrocyte autoimmunity. Methods: In the RRBC model, C57BL/6NJ mice were immunized weekly with 2 x 10 8 Wistar rat RBC for 10 weeks, leading to development of anti-mouse RBC autoantibodies. Groups of mice were treated twice weekly via intraperitoneal injection with povetacicept or a matched Fc isotype control. Analyses included anti-RRBC alloantibodies and autoantibodies bound to mouse erythrocytes (measured via direct anti-globulin test [DAT]). While significant anemia does not occur in this model, serum lactate dehydrogenase (LDH) was also measured as an index measure of subclinical hemolysis. Immune cell subset analysis of splenocytes by flow cytometry was also performed. Results: As compared to Fc control, povetacicept treatment significantly reduced levels of anti-RRBC and DAT of IgM and IgG isotypes and significantly limited serum LDH elevations at various timepoints during the study ( Figure 1). Furthermore, at 10 weeks, numbers of T follicular helper (Tfh) cells, total B cells, germinal center (GC) B cells, and plasma cells were significantly lower in spleens of povetacicept-treated mice ( Figure 2). Conclusions: Povetacicept effectively reduced pathogenic autoantibodies and key B cell populations (e.g., ASC) and limited serum LDH elevations in this mouse model of erythrocyte autoimmunity. These data suggest that povetacicept may reduce multiple pathogenic inflammatory processes including autoantibody production and may be an effective treatment for AIHA and other autoimmune cytopenias. Povetacicept is currently being evaluated in an open-label study (RUBY-4; NCT05757570) of adults with autoimmune cytopenias (ITP, AIHA, and CAD).

Infectious Complications in Autoimmune Hemolytic Anemia: A Multi-Center Italian Experience

Introduction: Infections may play an important role in the development or relapse of autoimmune hemolytic anemia (AIHA) as well as possible complications of long-term immunosuppression secondary to its management. The prevalence and severity of infection in AIHA are still under-investigated. Methods: Hereby we studied retrospectively 324 patients older than 18 years old, diagnosed with AIHA and followed at 10 Italian centers between 1981 and 2022, focusing on infectious complications and their predictors. Results: At diagnosis, median age was 60 years (range 18-94), with 27% of patients older than 70 years and with a slight male predominance (65%) and classified as warm AIHA in 53% (Table 1). Median Hb was 7.3 g/dL (2-14), median WBC of 7,5x10 9/L (1,4-94) and median platelets of 260x10 9/L (4-695). Sixty-two (60%) out of 103 patients presented lymphopenia. Among 111 evaluable patients, reduced serum IgG/IgA/IgM levels were detected in 37%, 27%, and 23%, respectively. Twenty-nine (9%) patients had Evans Syndrome. During a median follow-up of 35 months (1-553 months), patients received a median of 1 line of therapy (1-7), including steroids, rituximab, chemotherapy, and immunosuppressive (IS) drugs in 90%, 45%, 10% and 12% of cases, respectively. Twenty (6%) patients underwent splenectomy and 43 (13%) received intravenous Ig supplementation. Sixty-five (20%) patients presented at least one infection episodes, with 17 experiencing recurrences. Pneumonia was the most frequent (44 cases), followed by 11 sepsis and 4 urinary tract infections, requiring hospitalization in 37 (71%) of cases. Pathogens were isolated in 23 patients (62% viral and 38% bacterial agents). Overall, 17 (16%) suffered from SARS-CoV-2 infection, of whom 8 requiring specific therapy. Eleven (18%) patients were receiving prophylaxis at the time of infection, including acyclovir (18%), cotrimoxazole (18%), both (55%) or anti-HBV prophylaxis (18%). Forty-seven (77%) patients were on active treatment for AIHA at the time of infection (32 steroids, 8 rituximab, 1 IS and 11 not specified), and 16 (25%) also experienced a thrombotic event. Patients receiving more than one therapy lines had 2-fold higher probability of developing infections (RR 2.03, 1.27-3.25, p=0,0017), particularly for those treated with IS (RR 1.77, 1.04-3.01, p=0,041) and with rituximab (RR 1.96, 1.20-3.20, p=0,0048). Among patients with infections, median time from the last dose of rituximab was 15 months (range 1-147 months). Moreover, patients with thrombotic events were more likely to experience infection episodes (RR 2.41, 1.52-3.83, p=0,001). During observation, 55 patients (23%) died, among them 10 for AIHA complications, including 6 infections. Conclusions: In conclusion, infections complicate about 20% of AIHA. Most episodes occurred during active AIHA-therapy and were more common in patients with prior exposure to rituximab or IS, suggesting an iatrogenic effect. The association with thrombotic events may indicate a relationship with more severe AIHA. Strategies to reduce the burden of IS in AIHA should be pursued.

Mutations in Histone Lysine Methyltransferase Genes Are Associated with Autoimmune Cytopenias

Introduction Epigenetic mechanisms are important in regulation of gene expression by modifying chromatin structure to facilitate DNA accessibility (Lau et al Nat Immunol. 2018). DNA methylation and histone modifications are critical for the pathogenesis of hematologic malignancies and autoimmune diseases (Surace et al Front Immunol. 2019) Alterations in enzymes involved in histone modification are associated with immunodeficiencies, including Kabuki syndrome (KS), a rare genetic disorder associated with autoimmune cytopenias, such as immune thrombocytopenia (ITP) and autoimmune hemolytic anemia (AIHA) (Margot et al J Am Coll Med Genet 2020) caused by loss-of-function KMT2D and KDM6A mutations. Somatic mutations in the KMT2D gene have also been observed in patients with Cold Agglutinin Disease. (Małecka et al Br J Haematol. 2018). Aims: The aims of this study are: 1) to identify the frequency of mutations in histone methyltransferase genes (MT) KMT2D, KMT2A, KMT2C and KDM6A in patients with autoimmune cytopenias, and 2) to compare clinical, laboratory and immunological characteristics, and response to therapy in patients with or without mutation in MT and autoimmune cytopenias (AIC). Methods Data mining software from the electronic medical record was used to identify patients ≥ 18 years with a diagnosis of AIC, including ITP, warm and cold AIHA, autoimmune neutropenia, and Evans Syndrome (ES), who had Next Generation Sequencing (NGS) performed. Cytopenias due to malignancy, nutritional deficiency, medications, pregnancy, or infection were excluded. Patients were categorized into two groups based on the presence or absence of mutation in the MT genes (MT+, MT-) with variant allelic frequency (VAF) &amp;gt; 2%. Demographic, laboratory, and clinical characteristics, treatment outcomes, and NGS sequencing data were collected and compared between groups. Next, KMT2 mutations seen in patients with AIC were cross-referenced against the 1000 Genome Project (1000GP) population database to evaluate the frequency of polymorphisms in the general population (Auton et al Nature 2015). CADD in silico prediction algorithm was used to score the potential deleterious effect of MT mutations (Kirchner Nat Genet. 2014). Chi-Square test was used for categorical variables. Statistical analysis was completed in R software. Results Among 495 patients who underwent NGS, 79 (16%) had a mutation in MT genes. These mutations were present in 36% of patients with AIC as compared to 13% in those without AIC (p=0.0005). Among 55 patients with AIC, mutations in the MT genes were present in 20 patients (MT+), 35 patients did not have these mutations (MT-). KMT2C mutations were seen in 10 (50%) patients, KMT2D mutations in 9 patients (45%, one patient had two KMT2D mutations), 1 patient (5%) had both KMT2C &amp; KMT2D variants (Figure 1). The median VAF was 39.5% (IQR, 15.45 - 49.80). The MT+ group had a significantly higher proportion of Hispanic (60% vs 31%) and non-Hispanic White patients (25% vs 14%), p=0.038, Table 1. The median age at diagnosis for the MT+ cohort was younger compared to MT- (45.5 vs 58 years old, respectively), though not statistically significant. AIC diagnoses in both groups were ITP (44%) wAIHA (22%) cAIHA (9%) Autoimmune Neutropenia (2%), and ES (24%). Compared to the MT- group, the MT+ group had lower IgG levels (p=0.0041) and absolute lymphocyte count (p=0.041). MT+ patients with AIHA were more likely to have positive Direct Coombs and complement involvement. No significant differences were found in median nadir hemoglobin and platelet counts, need for therapy, or median number of lines of therapy. Best overall response to therapy was similar in the two groups (93%), with more complete responses in MT- group (55% vs 33%) though not statistically significant. Next, we assessed KMT2 polymorphisms in the general population. Most of the polymorphisms were not present in the 1000GP database and none had a frequency &amp;gt; 0.001. The average Phred score was 19.8; 12/20 patients had Phred score &amp;gt; 20, suggesting that most mutations are in the top 1% of the deleterious variants. Conclusion We report for the first time that patients with autoimmune cytopenias have a high frequency of variants in MT genes. Median allelic frequency close to 50% suggests potential germline predisposition to immune dysregulation and autoimmunity however further studies are needed to better understand the impact of these observations.

Cold Agglutinin Disease (CAD) Real-World Evidence (CADENCE) Registry: Update to the Study Design of the First International, Prospective CAD Registry

Cold agglutinin disease (CAD) is a rare chronic autoimmune hemolytic anemia (AIHA) characterized by classical complement pathway (CP)-mediated hemolysis. CAD is associated with a substantial disease burden negatively impacting quality of life (QoL), including severe fatigue, and increased risk of both thromboembolic events and early mortality. Due to the rarity of CAD, there is scarce information regarding its natural history, long-term impacts, and complications. Sutimlimab, a humanized monoclonal antibody that selectively inhibits the CP, is the first approved treatment for CAD. In the CARDINAL and CADENZA Phase 3 trials, sutimlimab reduced hemolysis, anemia, was generally well tolerated, and meaningfully improved QoL. The CADENCE Registry (NCT05791708) is a large international database of patients with CAD or cold agglutinin syndrome (CAS, a cold antibody-driven hemolytic anemia associated with an underlying condition). First launched in 2019, the first study patient was enrolled in 2022 following a COVID-19 pandemic-related hiatus. Presented here is an update on the current CADENCE protocol and study design. CADENCE is a multinational, multicenter, observational, prospective, longitudinal registry study enrolling patients ≥18 years of age diagnosed with CAD (diagnostic criteria: a monospecific direct antiglobulin test strongly positive for C3d and negative or weakly positive for immunoglobulin G and a cold agglutinin titer ≥1:64) or CAS (CAD diagnostic criteria, with causative infection, autoimmune disorder or overt malignancy). Exclusion criteria include patients with a diagnosis of warm or mixed AIHA and those actively participating in a CAD/CAS interventional trial. The main study objective is to better understand patient demographics, clinical characteristics, treatment patterns, healthcare resource utilization (HRU), natural history of disease, long-term clinical outcomes, and impact on patient QoL. A sutimlimab-treated cohort sub-study is ongoing to assess the real-world safety and effectiveness of sutimlimab in patients with CAD, fulfilling the regulatory commitment for a post-authorization safety study. The enrollment period is expected to last ~3 years and patients will be followed for 3 years after the last patient enrolled. Data collection will include both clinical assessments as per standard of care and patient-reported outcome (PRO) data collected at enrollment and at ~6-month interval follow-ups. Additional safety data will be collected for the sutimlimab cohort. The CADENCE Registry's first patient enrolled (after study restart) was in Q2 2022, with last patient's first visit expected in Q2 2025 and last patient's last visit expected in 2028 ( Figure). The registry will collect data on ~400 patients with CAD/CAS across ~90 sites in 8 countries: Austria, France, Germany, Italy, Japan, Spain, the UK, and the US. Among them, ≥30 patients with CAD treated with sutimlimab are expected to take part in the cohort study. Key data to be collected include clinical characteristics, disease complications, comorbidities, mortality, treatment regimens, HRU, and PROs. Biomarkers for hemolysis will be assessed, including lactate dehydrogenase, haptoglobin, total and indirect bilirubin. In the sutimlimab cohort, data will also be collected on adverse events (AEs), serious AEs, and AEs of special interest (serious infections, Raynaud's, arterial hypertension, autoimmune disorders, hypersensitivity/anaphylaxis, exposure in pregnancy, overdose). PRO measures include the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue, the 36-item Short Form Health Survey (SF-36), and the CAD symptoms and impact questionnaire (CAD-SIQ), a novel 11-item questionnaire specifically designed for CAD. Interim analyses will occur annually. Final analyses will be performed at study end both at regional and global levels. As of July 13, 2023, 47 of 82 targeted sites have been activated, and 113 of 405 targeted patients (CAD/CAS) have been enrolled, including 13 sutimlimab-treated patients. CADENCE is the first global registry for patients with CAD and will help advance understanding of the natural history and disease process of this rare condition. This registry will also assess the long-term safety and effectiveness of sutimlimab in patients with CAD in a real-world setting, providing clinicians with data that may help improve treatment practices.

Leukostasis Twist in Mantle Cell Lymphoma: Systematic Review and Case Report

Introduction: Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma. Patients often present with lymphadenopathy, early satiety, and B-symptoms. Despite up to 92% of MCL patients having peripheral blood involvement by flow cytometry, presentation with leukemic involvement and hyperleukocytosis are uncommon. Hyperleukocytosis, marked by a white blood count (WBC) &amp;gt;100 x 10 9/L, often leads to symptomatic leukostasis due to tissue hypoxia, generally found in acute leukemias. We conducted a systematic review of leukostasis in MCL, and present a case we encountered in our clinical practice of a non-nodal MCL variant showing leukostasis, spontaneous tumour lysis syndrome (TLS), and severe anemia to identify treatment strategies and outcomes. Methods: We searched PubMed for peer-reviewed articles and abstracts on “mantle cell lymphoma,” “hyperleukocytosis,” and “leukostasis.” All articles and abstracts that discuss hyperleukocytosis leading to leukostasis in MCL were included. Results: The search yielded eight results. After exclusions, five case reports and abstracts were included. These studies featured different MCL variants, presenting WBCs ranging from 121 to 1227 x 10 9/L, and various leukostasis symptoms. Leukapheresis was used in all five published cases, leading to lower WBCs and symptom improvement. Results are summarized in Table 1. Our patient was found to have the small lymphocyte variant of MCL, with WBC of 543.3 x 10 9/L on presentation. Our facility does not have leukapheresis capability. As a result, our initial treatment consisted of only supportive care and escalating doses of corticosteroids, with close monitoring for TLS. To our knowledge, this report is the first demonstration that IV methylprednisolone, without leukapheresis, is effective for acute management of leukostasis. Our patient's WBC reduced from 543.3 x 10 9/L to 230 x 10 9/L, leading to improved neurological function and oxygenation. Steroids were particularly useful in our patient with secondary, MCL-related warm autoimmune hemolytic anemia. Conclusion: This review highlights the importance of recognizing non-specific leukostasis symptoms, even in patients with mature B-cell lymphoproliferative disorders. Leukapheresis is effective in treating leukostasis in MCL patients. In hospitals without leukapheresis, escalating doses of IV methylprednisolone can be considered as a safe and effective strategy.

Mechanism of Actions, Efficacy, and Long-term Use of Steroids in Autoimmune Hemolytic Anemia (AIHA)

Autoimmune hemolytic anemia (AIHA) is a rare condition in which autoantibodies cause the loss of red blood cells. Steroids have been used to treat several illnesses, including AIHA. For now, steroids remain as the first line of treatment for AIHA. In AIHA, especially warm AIHA (wAIHA), steroids suppress autoantibody production and downregulate Fcγ receptors' expression on monocytes to prevent hemolysis. The type of steroids chosen for first-line therapy for wAIHA in pediatrics and adults are Prednisone (Prednisolone) and Methylprednisolone. At the same time, Dexamethasone is used as an alternative treatment in AIHA. Steroids show better therapeutic outcomes in the first 2-3 weeks of administration, but the proportion of patients who remain in remission after steroid discontinuation are still quite low. Long-term administration of steroids may affect bone, blood glucose metabolism, and hypothalamic-pituitary-adrenal axis (HPAA). However, steroids which have a linear pharmacokinetic profile, intermediate-acting glucocorticoids such as Prednisone (Prednisolone) or Methylprednisolone, and also tapering dose of steroids after 2-4 weeks administration will be safe for long term use as AIHA treatment.Keywords: steroids, glucocorticoid, corticosteroid, autoimmune hemolytic anemia, AIHA, mechanism of action, efficacy

Sirolimus is effective for primary refractory/relapsed warm autoimmune haemolytic anaemia/Evans syndrome: a retrospective single-center study

Background Some patients with warm autoimmune haemolytic anaemia (wAIHA) or Evans syndrome (ES) have no response to glucocorticoid or relapse. Recent studies found that sirolimus was effective in autoimmune cytopenia with a low relapse rate. Methods Data from patients with refractory/relapsed wAIHA and ES in Peking Union Medical College Hospital from July 2016 to May 2022 who had been treated with sirolimus for at least 6 months and followed up for at least 12 months were collected retrospectively. Baseline and follow-up clinical data were recorded and the rate of complete response (CR), partial response (PR) at different time points, adverse events, relapse, outcomes, and factors that may affect the efficacy and relapse were analyzed. Results There were 44 patients enrolled, with 9 (20.5%) males and a median age of 44 (range: 18–86) years. 37 (84.1%) patients were diagnosed as wAIHA, and 7 (15.9%) as ES. Patients were treated with sirolimus for a median of 23 (range: 6–80) months and followed up for a median of 25 (range: 12–80) months. 35 (79.5%) patients responded to sirolimus, and 25 (56.8%) patients achieved an optimal response of CR. Mucositis (11.4%), infection (9.1%), and alanine aminotransferase elevation (9.1%) were the most common adverse events. 5/35 patients (14.3%) relapsed at a median of 19 (range: 15–50) months. Patients with a higher sirolimus plasma trough concentration had a higher overall response (OR) and CR rate (p = 0.009, 0.011, respectively). At the time of enrolment, patients were divided into two subgroups that relapsed or refractory to glucocorticoid, and the former had poorer relapse-free survival (p = 0.032) than the other group. Conclusion Sirolimus is effective for patients with primary refractory/relapsed wAIHA and ES, with a low relapse rate and mild side effects. Patients with a higher sirolimus plasma trough concentration had a higher OR and CR rate, and patients who relapsed to glucocorticoid treatment had poorer relapse-free survival than those who were refractory.