Activated phosphoinositide 3-kinase delta (PI3KS) syndrome (APDS) is an ultra-rare, progressive genetic disease, characterised by immune deficiency and dysregulation, affecting individuals from birth. In a 12-week phase III randomised placebo-controlled trial, leniolisib, a selective PI3KS inhibitor, was well-tolerated and met both co- primary endpoints (change from Baseline in log10-transformed sum of product of diameters of index lymph nodes and percentage of na & iuml;ve/total B cells at Day 85). Here, prespecified subgroup analyses are reported in adolescents aged 12-17 years (leniolisib, n = 8; placebo, n = 4) and adults aged >= 18 (leniolisib, n = 13; placebo, n = 6). In both subgroups, leniolisib reduced lymphadenopathy (least squares mean change versus placebo: adolescents,-0.4 versus-0.1; adults,-0.3 versus 0.1) and increased the percentage of na & iuml;ve B cells (least squares mean change: adolescents, 44.5 versus-16.5; adults, 28.4 versus-1.1). Leniolisib was well-tolerated in both adolescents and adults. These results show leniolisib is an effective APDS treatment in both subpopulations. Plain Language Summary: What is activated PI3K delta syndrome (APDS)? APDS is an ultra-rare disease in which the immune system does not work correctly. People with APDS have a wide range of symptoms, including infections, certain organs associated with the immune system becoming larger, and worse quality of life. These symptoms generally start in childhood. Why was this study carried out?

Activated phosphoinositide 3-kinase delta (PI3K delta) syndrome (APDS) is an inborn error of immunity with clinical manifestations including infections, lymphoproliferation, autoim-munity, enteropathy, bronchiectasis, increased risk of lymphoma, and early mortality. Hyperactive PI3K delta signaling causes APDS and is selectively targeted with leniolisib, an oral, small molecule inhibitor of PI3K delta. Here, 31 patients with APDS aged >= 12 years were enrolled in a global, phase 3, triple-blinded trial and randomized 2:1 to receive 70 mg leniolisib or placebo twice daily for 12 weeks. Coprimary outcomes were differences from baseline in the index lymph node size and the percentage of naive B cells in peripheral blood, assessed as proxies for immune dysregulation and deficiency. Both primary out-comes were met: the difference in the adjusted mean change (95% confidence interval [CI]) between leniolisib and placebo for lymph node size was -0.25 (-0.38, -0.12; P = .0006; N = 26) and for percentage of naive B cells, was 37.30 (24.06, 50.54; P = .0002; N = 13). Leniolisib reduced spleen volume compared with placebo (adjusted mean difference in 3-dimensional volume [cm3], -186; 95% CI, -297 to -76.2; P = .0020) and improved key immune cell subsets. Fewer patients receiving leniolisib reported study treatment-related adverse events (AEs; mostly grades 1-2) than those receiving placebo (23.8% vs 30.0%). Overall, leniolisib was well tolerated and significant improvement over placebo was notable in the coprimary endpoints, reducing lymphadenopathy and increasing the percentage of naive B cells, reflecting a favorable impact on the immune dysregulation and deficiency seen in patients with APDS. This trial was registered at www.clinicaltrials.gov as #NCT02435173.

BACKGROUND:Activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS; or p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency) is an inborn error of immunity caused by PI3Kδ hyperactivity. Resultant immune deficiency and dysregulation lead to recurrent sinopulmonary infections, herpes viremia, autoimmunity, and lymphoproliferation. OBJECTIVE:Leniolisib, a selective PI3Kδ inhibitor, demonstrated favorable impact on immune cell subsets and lymphoproliferation over placebo in patients with APDS over 12 weeks. Here, we report results from an interim analysis of an ongoing open-label, single-arm extension study. METHODS:Patients with APDS aged 12 years or older who completed NCT02435173 or had previous exposure to PI3Kδ inhibitors were eligible. The primary end point was safety, assessed via investigator-reported adverse events (AEs) and clinical/laboratory evaluations. Secondary and exploratory end points included health-related quality of life, inflammatory markers, frequency of infections, and lymphoproliferation. RESULTS:Between September 2016 and August 2021, 37 patients (median age, 20 years; 42.3% female) were enrolled. Of these 37 patients, 26, 9, and 2 patients had previously received leniolisib, placebo, or other PI3Kδ inhibitors, respectively. At the data cutoff date (December 13, 2021), median leniolisib exposure was 102 weeks. Overall, 32 patients (87%) experienced an AE. Most AEs were grades 1 to 3; none were grade 4. One patient with severe baseline comorbidities experienced a grade 5 AE, determined as unrelated to leniolisib treatment. While on leniolisib, patients had reduced annualized infection rates (P = .004), and reductions in immunoglobulin replacement therapy occurred in 10 of 27 patients. Other observations include reduced lymphadenopathy and splenomegaly, improved cytopenias, and normalized lymphocyte subsets. CONCLUSIONS:Leniolisib was well tolerated and maintained durable outcomes with up to 5 years of exposure in 37 patients with APDS. CLINICALTRIALS:gov identifier: NCT02859727.

TREC and KREC are products of V(D)J recombination of Tand B-lymphocyte receptors in thymus and bone marrow, respectively. Low levels of TREC/KREC in peripheral blood are connected to T- and/or B-cell lymphopenia We have studied DNA of healthy children (n = 98) aged 0.0 (0–15.0) years, patients with primary immunodeficiency (n = 84) (SCID (n = 13), AT (n = 15), NBS (n = 17), X-linked agammaglobulinemia (n = 15), diseases of immune dysregulation (n = 14), Wicksott-Aldrich syndrome (n = 10)) aged 7.0 (0.1–15.0) years by multiplex RQ-PCR. The analysis of diagnostic significance has been performed by tracing of characteristic ROC curves and defining the area under the AUC curve. The AUC(TREC) and KREC for the SCID diagnostics has been equal to 1.00 ± 0.0 (p < 0.0001) with a diagnostic sensitivity and specificity of 100%. The AUC(TREC) for the X-linked agammaglobulemia diagnosis has made 0.62 ± 0.07 (p = 0.16) with diagnostic sensitivity and specificity of 14% and 93.6%, respectively. The AUC(KREC) has been 1.00 ± 0.0 (p < 0.0001) with diagnostic sensitivity and specificity of 100%. AUC(TREC) for patients with syndromes of chromosomal instability has been equal to 0.99 ± 0.007 (p < 0.0001) with diagnostic sensitivity of 93.4% and specificity of – 97.4%. The AUC(KREC) has been 0.98 ±0.015 (p < 0.0001)) with diagnostic sensitivity of 93.5% and specificity of 98.7%. In case of diseases of immune dysregulation, AUC(TREC) has been equal to 0.99 ± 0.007 (p < 0.0001) with diagnostic sensitivity of 93.3% and specificity of 96.3%. The AUC(KREC) has been 0.87 ± 0.06 (p < 0.0001) with diagnostic sensitivity of 86.6% and specificity of 94.6%. The AUC(TREC) for Wiskott-Aldrich syndrome diagnostics using analysis has made 0.63 ± 0.1 (p = 0.16), with sensitivity and specificity of 30% and 78.1%, respectively. AUC(KREC) has been 0.61 ± 0.09 (p = 0.23) with sensitivity of 20.0% and specificity of 92.35%. Evaluation of TREC/KREC is diagnostically significant during the primary diagnosis of diseases, associated with severe combined immune deficiency, agammaglobulinemia, syndromes of chromosomal instability, immune dysregulation. Evaluation of TREC/KREC has low information content and, thus, has no diagnostic significance for Wiskott-Aldrich syndrome.

Hereditary angioedema (HAE) is a rare, autosomal dominant genetic disorder that leads to sporadic episodes of swelling, which can affect any part of the body. In most cases, HAE is caused by a deficiency (type I) or dysfunction (type II) of C1-inhibitor (C1-INH), with an estimated prevalence of 1:10.000–1:50.000. HAE type I characterized by low antigenic and functional C1-INH levels, HAE type II characterized by normal or elevated antigenic but low functional C1-INH levels. Study groups included: patients with genetically confirmed HAE type I (group 1, n = 49); patients with genetically confirmed HAE type II (group 2, n = 13); patients with SARS-CoV-2-associated pneumonia with a median recovery period of 5 months (group 3, n = 11); patients with SARS-CoV-2 infection and without pneumonia with a median recovery period of 5 months (group 4, n = 41). The expression of the C1-INH gene was measured when HAE patients were not on prophylactic treatment. The results presented as a median (25%; 75%). C1-INH expression levels (normal range: 1.47 REU (1.07; 2.01)) were measured using real-time PCR and normalized to the level of GUS gene expression. All subjects consented to the study. The expression of the C1-INH gene in the first group was 0.31 REU (0.19; 0.60); in the second – 1.45 REU (1.26; 2.87); in the third – 0.47 REU (0.32; 0.88) and in the fourth – 0.76 REU (0.57; 1.29). We revealed that the third group had the similar range of C1-INH gene expression as in patients with HAE type I who have primary quantitative deficiency of C1-INH. Only in 27.3% (3/11) patients from group 3 and in 70.7% (29/41) patients from group 4 after recover from SARS-CoV-2 infection the expression level of the C1-INH gene have returned to the normal range. A recent studies displays that SARS-CoV-2 infection in human body directly causes a deficit in C1-INH, also there are evidences of the successful use of replacement therapy with a C1-INH in severe cases of COVID-19. However, the reason for the persistence of an acquired C1-INH deficiency in patients even with a several month recovery period remains to be elucidated.

•The oral PI3Kδ inhibitor leniolisib reduced lymphadenopathy and normalized immune cell subsets in patients with APDS, an inborn error of immunity.•Leniolisib was well tolerated in patients with APDS, with mostly grade 1 AEs and no serious AEs related to study treatment.

Warts, hypogammaglobulinemia, infections, and myelokathexis (WHIM) syndrome (WS) is a combined immunodeficiency caused by gain-of-function mutations in the C-X-C chemokine receptor type 4 ( CXCR4 ) gene. We characterize a unique international cohort of 66 patients, including 57 (86%) cases previously unreported, with variable clinical phenotypes. Of 17 distinct CXCR4 genetic variants within our cohort, 11 were novel pathogenic variants affecting 15 individuals (23%). All variants affect the same CXCR4 region and impair CXCR4 internalization resulting in hyperactive signaling. The median age of diagnosis in our cohort (5.5 years) indicates WHIM syndrome can commonly present in childhood, although some patients are not diagnosed until adulthood. The prevalence and mean age of recognition and/or onset of clinical manifestations within our cohort were infections 88%/1.6 years, neutropenia 98%/3.8 years, lymphopenia 88%/5.0 years, and warts 40%/12.1 years. However, we report greater prevalence and variety of autoimmune complications of WHIM syndrome (21.2%) than reported previously. Patients with versus without family history of WHIM syndrome were diagnosed earlier (22%, average age 1.3 years versus 78%, average age 5 years, respectively). Patients with a family history of WHIM syndrome also received earlier treatment, experienced less hospitalization, and had less end-organ damage. This observation reinforces previous reports that early treatment for WHIM syndrome improves outcomes. Only one patient died; death was attributed to complications of hematopoietic stem cell transplantation. The variable expressivity of WHIM syndrome in pediatric patients delays their diagnosis and therapy. Early-onset bacterial infections with severe neutropenia and/or lymphopenia should prompt genetic testing for WHIM syndrome, even in the absence of warts.

Introduction: Homeostatic PI3Kδ signaling is essential for healthy lymphocyte development. Dysregulated PI3Kδ signaling can promote the survival, proliferation, and accumulation of aberrant lymphocytes. Pathogenic germline variants in the genes encoding PI3Kδ cause the inborn error of immunity (IEI) activated PI3Kδ syndrome (APDS). Gain-of-function variants in PIK3CD or loss-of-function variants in PIK3R1 result in kinase hyperactivity, causing dysregulated B and T cells that lead to frequent infections, lymphoproliferation, enteropathy, autoimmune cytopenias, and increased risk of lymphoma. Other lymphoid malignancies have been treated with PI3Kδ inhibitors, despite those tumors typically lacking activating genetic variants in that isoform. We previously reported use of targeted inhibition of hyperactive PI3Kδ signaling with orally bioavailable, selective PI3Kδ inhibitor leniolisib in 6 patients with APDS in a 12-week, open-label, within-subject dose-escalation Phase 2/3 clinical trial (Part 1 of NCT02435173; Rao VK, et al. Blood. 2017), as well as an interim analysis of the open-label extension study (Rao VK, et al. Blood. 2018). Results from a 12-week randomized placebo-controlled trial of 31 patients with APDS were reported earlier this year (EHA abstract LB2369). Here we describe interim analysis outcomes from the ongoing open-label, single-arm, long-term extension study (NCT02859727). Methods: Thirty-seven patients with APDS aged ≥12 years were enrolled globally; 20 patients have been on leniolisib for nearly 2 years and 5 patients were exposed to it approximately 5 years. Thirty-five patients rolled over from NCT02435173; 2 patients were new to the study. The primary objective was to evaluate long-term safety of leniolisib. Spleen and index lymph node size were measured at either extension day (ED) 168 or 252. Presence of lymphoma, cytopenias, and infections were also assessed across multiple time points. Results: In patients with APDS, lymphoproliferation is variable and includes lymphadenopathy, hepatosplenomegaly, and nodular lymphoid hyperplasia; the first 2 were measured here. Lymph node size decreased at ED168/252 with a mean change from baseline (CFB) (standard deviation [SD], n) in the sum of product diameters of index nodes (cm2) at ED168 of -7.73 (6.47, 15) and at ED252 of -11.70 (15.97, 11). Spleen 3D volume (cm3) also decreased: mean CFB (SD, n) ED168, -198.48 (124.23, 16); ED252, -236.64 (165.20, 11). See Figure 1 for a representative image. Decreases were also observed in spleen bi-dimensional size. Three patients had a history of B-cell lymphoma prior to the trial: stage IV diffuse large B-cell lymphoma (2010), Hodgkin lymphoma with nodular sclerosis (2001), and extranodal marginal zone non-Hodgkin's lymphoma (MALT; 2005). All 3 remained in remission. There was a statistically significant decrease of -0.351 (p=0.0040) in infection rates with each additional year of leniolisib treatment, despite a concomitant reduction in immunoglobulin replacement therapy usage. This cohort had a range of autoimmune multilineage cytopenias; 17/31 improved or resolved (Table 1). Three patients who had normal absolute neutrophil count at baseline experienced transient neutropenia during the study, one had concomitant infections. Leniolisib was well tolerated; 32/37 patients experienced adverse events (AEs) Grades (Gr) 1-3. The majority were Gr 1 (55%), with no Gr 4 AEs and 1 Gr 5 AE. One patient with significant baseline comorbidities (pneumonia, necrotizing lymphadenitis, bronchiectasis, pancytopenia, disseminated mycoplasma infection, liver disease, edema, and cardiomyopathy) suffered cardiac arrest resulting in death at extension day 794 determined not related to study drug. This was the only discontinuation. No serious AEs were suspected related to leniolisib. Study drug related AEs occurred in 13.5% of patients. Severe gastrointestinal (GI) AEs are known to occur with use of other PI3Kδ inhibitors. On leniolisib 85.3% of GI AEs were Gr 1-2. Fifteen patients experienced GI AEs (excluding dental caries), 10 of whom had a history of GI disease. No GI AE was reported as related to study treatment. Conclusion: Long-term PI3Kδ pathway modulation with leniolisib administration was well-tolerated in patients with APDS, with continued improvement in lymphoproliferation and cytopenias and no recurrence of lymphoma following study drug exposure up to 5 years. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

We seek to identify the role of the microbiome in immune dysregulation in Common Variable Immunodeficiency (CVID).CVID patients have two distinct phenotypes: patients who develop infections-only (INF), and patients who develop autoimmune and inflammatory complications (noninfectious complications (NIC)).Compared to INF-CVID, NIC-CVID patients have higher morbidity and mortality rates.Studies showed associations between NIC-CVID and gut microbiome aberrations, including imbalanced microbial composition, leaky gut, and systemic inflammation.To investigate the role of dysbiosis in the immune responses in CVID, we performed fecal microbiota transplant (FMT) from CVID patients to C57Bl/6J Germ-Free (GF) mice.GF-mice received FMT from NIC-CVID, INF-CVID, or a healthy control (CTL).Thirty days later, gut microbial alpha and beta diversity were significantly different between NIC, INF, and CTL-FMT recipients.Furthermore, FMT recipients from all CVID donors (NIC and INF) had significantly higher serum IgG2b and IgG2c, indicating inflammation.We next treated 50% of the mice in each group with normal saline (NS) and 50% with a single dose of intraperitoneal human IgG (h-IgG).Compared to NS, h-IgG resulted in a significant change in gut microbiome beta diversity in NIC-FMT but not in INF or CTL-FMT recipients.In addition, IgG-treated NIC-FMT recipients had a decrease in the relative abundance of Eggerthella, Bifidobacterium, and Ruminococcaceae genera.Dysregulation of the same genera has been described in CVID patients.Thus, we provide a proof of concept that FMT from CVID patients to GFmice recapitulates the microbiome alteration seen in CVID patients.Our data are from a single donor per group; however, confirmatory experiments using additional donor samples are underway.Our work will help provide new insight into immune dysregulation in CVID.It will also help identify the anti-commensal effects of IgG therapy.Our ultimate goal is to develop therapeutics to modulate the gut microbiome and treat and prevent NIC development in CVID.There is a significant difference in alpha and beta gut microbiome diversity between NIC, INF, and CTL FMT recipients: Beta diversity between GF mice 30 days following FMT.Principal-coordinate analysis plots of Unifraction distances of fecal microbiota generated from 16S rRNA gene sequence analysis.Axis labels indicate the percentage of variance explained by the respective principal coordinate axis.PC1, principal coordinate 1; PC2, principal coordinate 2. Feces were freshly collected from GF (C57Bl/6J) mice (n=8/group, all males, ages 8-12 weeks), mice housed at the Gnotobiotics Core, BCM).Blue: NIC.Red: INF.Green: CTL.

Background Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare disease. Few states in developing countries have an adequate management of HAE, but none of them belongs to the former USSR area. This study analyses data from C1-INH-HAE patients from Belarus. Methods Data about clinical characteristics, genetics, access to diagnosis and treatment were collected from 2010 by the Belarusian Research Center for Pediatric Oncology, Hematology and Immunology in Minsk. A questionnaire about attacks, prophylactic (LTP) and on-demand therapy (ODT) was administered to patients. Results We identified 64 C1-INH-HAE patients belonging to 26 families, 27 (42.2%) of which were diagnosed in the last 3 years. The estimated minimal prevalence was 1:148,000. Median age at diagnosis was 29 years, with diagnostic delay of 19 years. Thirty-eight patients answered a questionnaire about therapy. Eleven patients did not use any treatment to resolve HAE attacks. Twenty-seven patients underwent ODT: 9 with appropriate treatments, and 18 with inappropriate treatments. Nine patients used LTP with attenuated androgens and 1 with tranexamic acid. Thirty-two patients answered a questionnaire about attacks and triggers: 368 angioedema attacks were reported, with an average of 10 attacks per year. We found 24 different SERPING1 variants: 9 missenses, 6 in splice sites, 6 small deletions, 2 nonsense, 1 large deletion; 7 have not been previously described. De novo variants were found in 11 patients. Conclusions C1-INH-HAE diagnosis and management in Belarus is improved as seen from the high number of new diagnosis in the last 3 years. Next steps will be to reduce the diagnostic delay and to promote the LTP and ODT.

Hereditary angioedema due to C1 inhibitor deficiency (C1-INH-HAE) is a rare disease. Few states in developing countries have an adequate management of HAE, but none of them belongs to the former USSR area. This study analyses data from C1-INH-HAE patients from Belarus. Data about clinical characteristics, genetics, access to diagnosis and treatment were collected from 2010 by the Belarusian Research Center for Pediatric Oncology, Hematology and Immunology in Minsk. A questionnaire about attacks, prophylactic (LTP) and on-demand therapy (ODT) was administered to patients. We identified 64 C1-INH-HAE patients belonging to 26 families, 27 (42.2%) of which were diagnosed in the last 3 years. The estimated minimal prevalence was 1:148000. Median age at diagnosis was 29 years, with diagnostic delay of 19 years. Thirty-eight patients answered a questionnaire about therapy. Seventeen (44.7%) underwent ODT: 6 (15.8%) with appropriate treatments, and 11 (28.9%) with inappropriate treatments. Nine (23.6%) used LTP with attenuated androgens and twelve (31.5%) recovered spontaneously. Thirty-two patients answered a questionnaire about attacks and triggers: 368 angioedema attacks were reported, with an average of 10 attacks per year. We found 24 different SERPING1 variants: 9 missenses, 6 in splice sites, 6 small deletions, 2 nonsense, 1 large deletion; 7 have not been previously described. De novo variants were found in 11 patients. C1-INH-HAE diagnosis and management in Belarus is improved as seen from the high number of new diagnosis in the last 3 years. Next steps will be to reduce the diagnostic delay and to promote the LTP and OTD.