Clinical spectrum and features of activated phosphoinositide 3-kinase δ syndrome: A large patient cohort study

Prevalence of Ophthalmological Manifestations in Patients with Inborn Errors of Immunity: A Systematic Review and Meta-Analysis

BACKGROUND

Although some reports indicate ocular involvement in Inborn Errors of Immunity (IEI) patients, the characteristics of this association remain unclear. Increased awareness can facilitate early diagnosis and prevention of visual complications.

OBJECTIVE

To determine the prevalence and characterize ophthalmological manifestations in patients with IEI.

METHODS

A systematic literature search was performed across Embase, PubMed, and Lilacs. Observational studies with at least 10 IEI patients exhibiting ophthalmological manifestations were reviewed. A meta-analysis using a random effects model, weighted proportion, and 95% confidence intervals were reported as appropriate.

RESULTS

Sixty-two articles out of the 6,884 studies were included. The pooled prevalence of ocular manifestations in IEI patients was 54% (95%CI = 39-69), with a mean age of 11.1 ± 7.8 years and male predominance. Regarding the type of IEI with ocular involvement, the most frequently affected group was the Combined immunodeficiencies with associated or syndromic features (82%, 95%CI = 66-91), followed by the diseases of immune dysregulation (73%, 95%CI = 27-95), auto-inflammatory disorders (48%, 95%CI = 10-88), and congenital defects of phagocytes (39%, 95%CI = 11-76). Europe had the highest prevalence of patients with ocular manifestations (68%, 95%CI = 32-90). The most common ocular manifestations observed in IEI patients were those affecting ocular mobility, followed by those that involved the anterior segment, posterior segment, eyelids, and adnexal structures.

CONCLUSIONS

These results highlight a significant burden of ocular involvement in IEI patients, mainly during childhood and associated with amblyogenic factors. Therefore, ophthalmologists, pediatricians, and immunologists must be involved in early detection to prevent ocular complications and overall well-being.

Overall survival among patients with activated phosphoinositide 3-kinase delta syndrome (APDS)

BACKGROUND

This study aimed to describe overall survival (OS) of patients with APDS relative to the global population as well as among subsets of patients with concurrent lymphoma or hematopoietic stem cell transplant (HSCT) relative to the overall APDS population.

METHODS

Patient-level data were extracted from a recent systematic literature review of 351 unique patients with APDS. OS was evaluated using the Kaplan-Meier method up to age 65 years. OS rate and corresponding 95% CI were reported at each decade of age. Global mortality estimates were obtained from World Health Organization life tables for 2019.

RESULTS

Of the 351 patients with APDS (APDS1, 267 [76.1%]; APDS2, 83 [23.6%]; unspecified, 1 [0.3%]), 41 (11.7%) died. The OS rate was 25.0% (95% CI, 1.6-62.7%) by the last death event at 64 years of age. Starting at 12 years of age, the OS rate was numerically lower in patients with APDS relative to the global population (median OS, 64 vs. 75 years, respectively). Relative to the overall APDS population, OS rates were numerically similar in those who underwent HSCT (median OS, 64 years for both; p = 0.569), whereas OS rates were numerically lower in patients with concurrent lymphoma (median OS, 41 vs. 64 years, respectively; p = 0.109). Publication bias in source data was a possible limitation.

CONCLUSION

Reduced survival in patients with APDS suggests a high disease burden, particularly in those with concurrent lymphoma. These results highlight the unmet need for disease-modifying treatments for APDS.

Overlapping Clinical Phenotypes in Patients with Primary Ciliary Dyskinesia or Activated Phosphoinositide 3-Kinase Delta Syndrome

Primary ciliary dyskinesia and activated phosphoinositide 3-kinase delta syndrome type 1 present similarly, with recurrent respiratory infections and reduced nasal nitric oxide levels. When diagnostic confirmation of primary ciliary dyskinesia with genetic testing and/or ciliary electron microscopy is inconclusive, activated phosphoinositide 3-kinase delta syndrome type 1 and other inborn errors of immunity must be investigated.

Case Report: Activated PI3-kinase-δ syndrome and ovarian malignancies: a case series from the European ESID-APDS registry

Activated phosphoinositide-3-kinase-delta (PI3Kδ) syndrome (APDS) is an autosomal dominant inborn error of immunity (IEI) characterized by combined immunodeficiency and immune dysregulation with increased risk for lymphoma and other non-lymphoid malignancies. We describe five patients with ovarian malignancies among 110 female APDS patients participating in the European Society for Immunodeficiencies (ESID) registry and identified three additional cases in the literature. These findings document a relevant predisposition to these non-hematological malignancies in APDS patients.

Case Report: Clinical manifestations of uncommon monogenic disorders: revisiting activated phosphoinositide 3-kinase delta syndrome 2

Aim

Pediatricians are trained to identify recurrent or unusual infections in children, prompting evaluation for inborn errors of immunity (IEI). Some monogenic IEI, however, may present atypically. This study describes our experience with children diagnosed with activated phosphoinositide 3-kinase delta syndrome (APDS2) including unusual presentations.

Methods

A retrospective review was conducted on two children diagnosed with APDS2 at Shaare Zedek and Sheba Tel-Hashomer Medical Centers in Israel. Both patients underwent immune assessments, genetic testing, and treatment between 2019 and 2024.

Results

Two patients, a 17-year-old female (P1) and a 7-year-old male (P2), were diagnosed with APDS2 after presenting with recurrent juvenile parotitis (P1) and severe lymphadenopathy (P2). Immunologic evaluation revealed hypogammaglobulinemia and combined immune deficiency. Genetic testing identified PIK3R1 variants (c.1425 + 1G > T in P1 and c.1425 + 1G > C in P2). Both received intravenous immunoglobulins and prophylactic antibiotics. P2 was treated with rapamycin, leading to resolution of lymphadenopathy.

Conclusion

This report highlights the clinical presentation of APDS2, a rare monogenic IEI in children, including the atypical manifestation of RJP and the common feature of lymphadenopathy. Pediatricians should stay vigilant for red flags of IEI during clinical evaluations, as early diagnosis and multidisciplinary care are crucial for effective management.

Invasive fungal disease in a large cohort of hospitalized children with inborn errors of immunity in China

BACKGROUND

Invasive fungal disease (IFD) is a common complication observed in inborn errors of immunodeficiency (IEI) patients, and little is known about the overall prevalence of IFD in IEI patients. We aimed to summarize the fungal spectrum and outcomes of IFDs in a Chinese cohort of hospitalized patients with IEI.

METHODS

In this retrospective study, 607 IEI patients hospitalized from January 2018 to June 2022 were included. Demographic, clinical, and fungal infection data and IEI patient characteristics were collected and analyzed according to the IEI classification.

RESULTS

One hundred and two IEI patients were diagnosed with proven or probable IFD. The overall prevalence of IFD was 17% (102/607). There were 29 different genotypes, among which CYBB (25%), CD40LG (9%), and RAG1 (7%) mutations were the most common. Most IFD infections (87/102) were caused by one fungus. Invasive Aspergillus, Pneumocystis jirovecii pneumonia, and Penicillium infections were more commonly observed in patients with congenital defects in phagocytes, immunodeficiencies affecting cellular and humoral immunity, and defects in innate immunity, respectively. Most IFDs observed in IEI patients were single-site infections, most of which were lung infections (74%). Seventeen patients were diagnosed with disseminated IFDs, nine of which were caused by Penicillium. All patients received antifungal treatments. Eight patients (8%) died within 3 months of IFD diagnosis.

CONCLUSIONS

IFD occurrence suggests the presence of immunity impairment. The IFD fungal profile may indicate different types of IEI. Early recognition of immunodeficiency and optimal timing of antifungal therapy can reduce fatality in IEI patients.

SIV-specific neutralizing antibody induction following selection of a PI3K drive-attenuated nef variant

HIV and simian immunodeficiency virus (SIV) infections are known for impaired neutralizing antibody (NAb) responses. While sequential virus-host B cell interaction appears to be basally required for NAb induction, driver molecular signatures predisposing to NAb induction still remain largely unknown. Here we describe SIV-specific NAb induction following a virus-host interplay decreasing aberrant viral drive of phosphoinositide 3-kinase (PI3K). Screening of seventy difficult-to-neutralize SIVmac239-infected macaques found nine NAb-inducing animals, with seven selecting for a specific CD8+ T-cell escape mutation in viral nef before NAb induction. This Nef-G63E mutation reduced excess Nef interaction-mediated drive of B-cell maturation-limiting PI3K/mammalian target of rapamycin complex 2 (mTORC2). In vivo imaging cytometry depicted preferential Nef perturbation of cognate Envelope-specific B cells, suggestive of polarized contact-dependent Nef transfer and corroborating cognate B-cell maturation post-mutant selection up to NAb induction. Results collectively exemplify a NAb induction pattern extrinsically reciprocal to human PI3K gain-of-function antibody-dysregulating disease and indicate that harnessing the PI3K/mTORC2 axis may facilitate NAb induction against difficult-to-neutralize viruses including HIV/SIV.

Genetic Etiologies and Outcomes in Malignancy and Mortality in Activated Phosphoinositide 3-Kinase Delta Syndrome: A Systematic Review

INTRODUCTION

This analysis evaluated literature on patients with activated phosphoinositide 3-kinase delta syndrome (APDS) to better understand the genetic etiologies and occurrence of mortality in this population.

METHODS

A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses approach, including all articles published in English prior to March 13, 2023, in PubMed and Embase. Patients included in the study had reported either (1) APDS diagnosis or (2) ≥ 1 clinical sign consistent with APDS and a first-degree relative with genetically confirmed APDS. Reported age at last observation was also a required outcome. Publications not meeting these criteria were excluded. Data were summarized using descriptive statistics.

RESULTS

The search identified 108 publications describing 351 unique patients with 39 distinct disease-causing variants. Among these, 41 (12%) deaths were reported, with a mean age at last follow-up of 19.6 (range, 1-64) years. A cause of death was reported for 80% (33/41) of deaths; lymphoma (24%, 10/41) and infections (22%, 9/41) were the most common causes. Types of infections causing death were severe uncontrollable infections (n = 3), sepsis (n = 2), viral infection (varicella zoster pneumonitis [n = 1], cytomegalovirus and adenovirus [n = 1], and Epstein-Barr virus [n = 1]), and infection (n = 1). Mean age at death for lymphoma was 24.9 (range, 1-41) years, and all nine patients who died from infections died before the age of 15 years. The mean age at first APDS symptom was 2.0 (range, < 1-22) years, and mean age at APDS diagnosis was 13.4 (range, 0-56) years; the mean time between symptoms and diagnosis was 10.6 (range, 0-44) years. Limitations of the study were primarily related to the data source.

CONCLUSION

Patients with APDS suffer early mortality, largely from lymphoma and infection, with large time gaps between symptoms and diagnosis. These findings highlight the need for improved diagnostics, earlier genetic testing for APDS, increased awareness of familial testing, and targeted therapies.

Listeria Meningitis as an Indication of Undiagnosed Primary Immune Deficiency, Activated Phosphoinositide 3-Kinase Delta Syndrome: A Case Report

INTRODUCTION

Listeria monocytogenes is a Gram-positive bacillus that causes severe infections mainly in newborns, pregnant women, immunocompromised individuals, and elderly. In this report, we present a case of immune dysregulation that presented with invasive Listeria infection despite the absence of these risk factors.

CASE

A previously healthy 5-year-old girl developed L. monocytogenes meningitis, which is unusual given her age and lack of typical risk factors. The patient initially presented with fever, diarrhea and altered mental status, unresponsive to empiric antibiotic treatment. Besides clinical diagnosis of meningitis, laboratory tests revealed pleocytosis and positive polymerase chain reaction test for L. monocytogenes in cerebrospinal fluid. Despite initial improvement, the patient developed proteinuria and hypertension and was later diagnosed with focal class 3 lupus nephritis following a renal biopsy. Given the atypical nature of her L. monocytogenes infection, persistent organomegaly, and lupus nephritis, further immunological evaluation was conducted. Genetic testing revealed a de-novo gain-of-function mutation in the PIK3CD gene, confirming the diagnosis of Activated Phosphoinositide 3-Kinase Delta Syndrome 1 (APDS1), a rare primary immunodeficiency characterized by lymphoproliferation and autoimmunity. The patient was started on immunoglobulin replacement therapy and prophylactic trimethoprim-sulfamethoxazole. No recurrence of severe infection occurred during 2 years of follow-up.

CONCLUSION

This case underscores the importance of considering underlying immune dysregulations in pediatric patients with atypical presentation of Listeria infections.

Comparative efficacy of leniolisib (CDZ173) versus standard of care on rates of respiratory tract infection and serum immunoglobulin M (IgM) levels among individuals with activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS): an externally controlled study

Leniolisib, an oral, targeted phosphoinositide 3-kinase delta (PI3Kδ) inhibitor, was well-tolerated and efficacious versus placebo in treating individuals with activated PI3Kδ syndrome (APDS), an ultra-rare inborn error of immunity (IEI), in a 12-week randomised controlled trial. However, longer-term comparative data versus standard of care are lacking. This externally controlled study compared the long-term effects of leniolisib on annual rate of respiratory tract infections and change in serum immunoglobulin M (IgM) levels versus current standard of care, using data from the leniolisib single-arm open-label extension study 2201E1 (NCT02859727) and the European Society for Immunodeficiencies (ESID) registry. The endpoints were chosen following feasibility assessment considering comparability and availability of data from both sources. Baseline characteristics between groups were balanced through inverse probability of treatment weighting. The leniolisib-treated group included 37 participants, with 62 and 49 participants in the control group for the respiratory tract infections and serum IgM analyses, respectively. Significant reductions in the annual rate of respiratory tract infections (rate ratio: 0.34; 95% confidence interval [CI]: 0.19, 0.59) and serum IgM levels (treatment effect: -1.09 g/L; 95% CI: -1.78, -0.39, P = 0.002) were observed in leniolisib-treated individuals versus standard of care. The results were consistent across all sensitivity analyses, regardless of censoring, baseline infection rate definition, missing data handling, or covariate selection. These novel data provide an extended comparison of leniolisib treatment versus standard of care, highlighting the potential for leniolisib to deliver long-term benefits by restoring immune system function and reducing infection rate, potentially reducing complications and treatment burden.

Piloting an automated query and scoring system to facilitate APDS patient identification from health systems

Introduction

Patients with activated PI3Kδ syndrome (APDS) may elude diagnoses for nearly a decade. Methods to hasten the identification of these patients, and other patients with inborn errors of immunity (IEIs), are needed. We sought to demonstrate that querying electronic health record (EHR) systems by aggregating disparate signs into a risk score can identify these patients.

Methods

We developed a structured query language (SQL) script using literature-validated APDS-associated clinical concepts mapped to ICD-10-CM codes. We ran the query across EHRs from 7 large, US-based medical centers encompassing approximately 17 million patients. The query calculated an "APDS Score," which stratified risk for APDS for all individuals in these systems. Scores for all known patients with APDS (n=46) were compared.

Results

The query identified all but one known patient with APDS (98%; 45/46) as well as patients with other complex disease. Median score for all patients with APDS was 9 (IQR = 5.75; range 1-25). Sensitivity analysis suggested an optimal cutoff score of 7 (sensitivity = 0.70).

Conclusion

Disease-specific queries are a relatively simple method to foster patient identification across the rare-disease spectrum. Such methods are even more important for disorders such as APDS where an approved, pathway-specific treatment is available in the US.

Expert insights on Hodgkin's lymphoma development in an activated PI3K delta syndrome patient undergoing leniolisib treatment

Activated PI3K delta syndrome (APDS) is a primary immunodeficiency that is caused by mutations in the PI3K signalling pathway resulting in either gain-of-function or loss-of-function phenotypes of APDS 1 and 2. Malignancy is one of the most serious complications associated with APDS patients, with the most commonly occurring of these being lymphoma, and is the most common cause of death in APDS patients. Management of APDS is complex and variable due to the heterogeneous nature of the disease and ranges from antimicrobial and immunosuppressant agents to haematopoetic stem cell transplantation. More recently, an increasing level of interest has been shown in the use of more targeted agents such as PI3Kδ-specific inhibitors. Here, we provide expert perspective on the suspected causality of a case of lymphoma observed in a 20-year-old female patient who was included in a clinical trial of leniolisib, a PI3K inhibitor.

A randomised, placebo-controlled, phase III trial of leniolisib in activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS): Adolescent and adult subgroup analysis

Activated phosphoinositide 3-kinase delta (PI3Kδ) 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 PI3Kδ 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 naïve/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 naïve 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 PI3Kδ 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? Current treatments only treat the symptoms of APDS, rather than correcting the cause of the problem. These treatments can also have significant side effects. A new medication for APDS called leniolisib aims to treat the underlying cause of the disease. This publication reports results from a clinical trial of leniolisib which compared patients who received leniolisib with patients who received a placebo. The aim of this report was to examine these clinical trial results to understand if leniolisib is effective and safe when treating both adolescents (12-17 years old) and adults (18 years and older) with APDS. What were the results of this study? Leniolisib improved the number of certain immune cells, compared to patients who did not receive leniolisib, in both adolescents and adults with APDS. Leniolisib also reduced the size of the enlarged immune system organs in both adolescents and adults with APDS. There were no major safety concerns for either age group who received leniolisib. What do these results mean? These results show that leniolisib can help the immune system to work in a way that is closer to those without APDS. This new treatment is effective and generally well-tolerated for both adolescents and adults. These results indicate that people with APDS are able to start treatment with leniolisib during adolescence, which may slow the build-up of symptoms and may also have a positive impact on the quality of their lives.

Report of the Italian Cohort with Activated Phosphoinositide 3-Kinase δ Syndrome in the Target Therapy Era

BACKGROUND

Activated Phosphoinositide 3-Kinase (PI3K) δ Syndrome (APDS), an inborn error of immunity due to upregulation of the PI3K pathway, leads to recurrent infections and immune dysregulation (lymphoproliferation and autoimmunity).

METHODS

Clinical and genetic data of 28 APDS patients from 25 unrelated families were collected from fifteen Italian centers.

RESULTS

Patients were genetically confirmed with APDS-1 (n = 20) or APDS-2 (n = 8), with pathogenic mutations in the PIK3CD or PIK3R1 genes. The median age at diagnosis was 15.5 years, with a median follow-up of 74 months (range 6-384). The main presenting symptoms were respiratory tract infections alone (57%) or associated with lymphoproliferation (17%). Later, non-clonal lymphoproliferation was the leading clinical sign (86%), followed by respiratory infections (79%) and gastrointestinal complications (43%). Malignant lymphoproliferative disorders, all EBV-encoding RNA (EBER)-positive at the histological analysis, occurred in 14% of patients aged 17-19 years, highlighting the role of EBV in lymphomagenesis in this disorder. Diffuse large B-cell lymphoma was the most frequent. Immunological work-up revealed combined T/B cell abnormalities in most patients. Treatment strategies included immunosuppression and PI3K/Akt/mTOR inhibitor therapy. Rapamycin, employed in 36% of patients, showed efficacy in controlling lymphoproliferation, while selective PI3Kδ inhibitor leniolisib, administered in 32% of patients, was beneficial on both infections and immune dysregulation. Additionally, three patients underwent successful HSCT due to recurrent infections despite ongoing prophylaxis or lymphoproliferation poorly responsive to Rapamycin.

CONCLUSIONS

This study underscores the clinical heterogeneity and challenging diagnosis of APDS, highlighting the importance of multidisciplinary management tailored to individual needs and further supporting leniolisib efficacy.

Unmasking inborn errors of immunity: identifying the red flags of immune dysregulation

Inborn errors of immunity (IEI) are rare diseases that affect the immune system. According to the latest International Union of Immunological Societies (IUIS) classification, 485 different IEI have been identified. Even if increased susceptibility to infections is the best-known symptom, IEI are no longer defined by the higher likelihood of infections alone. Immune dysregulation with autoimmune disease and hyperinflammation, lymphoproliferation, and malignancy are common manifestations and could be the only symptoms of IEI that must be recognized. An exclusive focus on infection-centered warning signs would miss around 25% of patients with IEI who initially present with other manifestations. Timely and appropriate diagnosis and treatment are essential to enhance the quality of life (QoL) and, in some cases, survival, as patients are susceptible to life-threatening infections or autoimmunity. In addition, the advantage of early diagnosis in IEI with immune dysregulation (i.e. CTLA4 deficiency, LRBA deficiency, NF-kB1/NF-kB2 deficiency, activated phosphoinositide 3-kinase delta syndrome -APDS-) is the initiation of targeted therapies with precise re-balancing of the dysregulated immune pathways (i.e., biologicals, selective inhibitors) or definitive therapy (i.e., HSCT).

Beyond FAScinating: advances in diagnosis and management of autoimmune lymphoproliferative syndrome and activated PI3 kinase δ syndrome

Refractory autoimmune mutilineage cytopenias can present in childhood associated with chronic nonmalignant lymphoproliferation (splenomegaly, hepatomegaly, and/or lymphadenopathy). Cytopenias due to peripheral destruction and sequestration have been well recognized since the 1950s and are often lumped together as eponymous syndromes, such as Evans syndrome and Canale-Smith syndrome. Though their clinical and genetic diagnostic workup may appear daunting, it can provide the basis for early intervention, genetic counseling, and empirical and targeted therapies. Autoimmune lymphoproliferative syndrome (ALPS), activated phosphatidylinositol 3-kinase delta syndrome (APDS), and many other related genetic disorders are otherwise collectively known as inborn errors of immunity (IEI). They present in early childhood as refractory autoimmune cytopenias due to immune dysregulation leading to lymphadenopathy, splenomegaly, and increased susceptibility to lymphoma. More recently, controlled clinical trials have shown that some of these immune system disorders with hematological manifestations might be more readily amenable to specific targeted treatments, thus preventing end-organ damage and associated comorbidities. Over the last 20 years, both rapamycin and mycophenolate mofetil have been successfully used as steroid-sparing long-term measures in ALPS. Current therapeutic options for APDS/PASLI (phosphoinositide 3-kinase [PI3K]-associated senescent T lymphocytes, lymphadenopathy, and immunodeficiency) include the orally bioavailable PI3Kδ inhibitor, leniolisib, which was licensed by the US Food and Drug Administration (FDA) in 2023 for use in individuals older than 12 years as a targeted treatment. Paradigms learned from patients with rare genetic disorders like ALPS and APDS may help in exploring and streamlining molecular therapy strategies in the wider group of IEIs presenting with refractory cytopenias and lymphoproliferation.

Bridging the gap: neurodevelopmental disorder risks in inborn errors of immunity

PURPOSE OF REVIEW

The aim of this review is to examine published reports of neurodevelopmental phenotypes in patients with inborn errors of immunity (IEI). We briefly discuss potential interactions between the immune and the central nervous system and the implications of this crosstalk for current clinical management guidelines.

RECENT FINDINGS

An increasing number of reports have described neurodevelopmental disorders (NDDs) comorbid with immune-mediated signs. However, the prevalence of this association in IEIs remains unknown.

SUMMARY

IEIs comprise a group of clinically heterogeneous disorders associated with a number of nonimmune comorbidities. Although certain neurological conditions such as microcephaly are recognized as associated features of some IEIs, NDDs are less well described. We reviewed published clinical descriptions of IEIs and found a number of comorbid NDDs in these patients, including autism spectrum disorder (ASD), behavioral deficits, and intellectual disability. Given the lack of uniform assessments for NDDs, we suspect they may be underdiagnosed in IEIs. As NDDs manifest early and can result in life-long cognitive and emotional deficits, which diminish quality of life and increase healthcare utilization, we hope to elucidate relevant pathomechanisms and raise clinician awareness of these comorbidities so appropriate and timely interventions are sought.

Transplantation for immune dysregulatory disorders: current themes and future expectations

PURPOSE OF REVIEW

Primary immune regulatory disorders (PIRDs) are an increasing indication for hematopoietic stem cell transplant (HCT) in pediatric patients. Here, we provide an updated overview of HCT for PIRDs, and discuss future avenues for improvement in outcomes.

RECENT FINDINGS

There are now more than 50 described monogenic PIRDs, which impact all aspects of immune tolerance, regulation, and suppression. Disease characteristics are highly variable, and HCT remains the only option for cure. We review advances in targeted therapies for individual PIRDs, which have significantly improved outcomes and the ability to safely bridge to transplant. Additionally, advances in GVHD prevention, graft manipulation, personalized conditioning regimens, and supportive care have all increased survival after HCT. The high inflammatory state increases the risk of nonengraftment, rejection, and autologous reconstitution. Therapy to reduce the inflammatory state may further improve outcomes. In addition, although younger patients with fewer comorbidities have better outcomes, the clinical courses of these diseases may be extremely variable thereby complicating the decision to proceed to HCT.

SUMMARY

HCT for PIRDs is a growing consideration in cell therapy. Yet, there remain significant gaps in our understanding of which patients this curative therapy could benefit the most. Here, we review the current data supporting HCT for PIRDs as well as areas for future improvement.

Case Report: Early-onset or recalcitrant cytopenias as presenting manifestations of activated PI3Kδ syndrome

Background

Patients with recurrent, chronic, or refractory cytopenias represent a challenging subgroup that may harbor an underlying diagnosis, such as an inborn error of immunity (IEI). Patients with IEIs such as activated phosphoinositide 3-kinase delta syndrome (APDS), frequently have hematologic manifestations, but these are not often reported as presenting symptoms. As a result, IEIs may be overlooked in patients presenting with early and/or recalcitrant cytopenias. Here, we describe the diagnostic journey and management of three patients who presented to a pediatric hematologist/oncologist with early-onset or recalcitrant cytopenias and were ultimately diagnosed with APDS.

Case presentations

Patients presented with early-onset and/or refractory cytopenias, with two of the three developing multilineage cytopenias. Prior to an APDS diagnosis, two patients underwent a total of approximately 20 procedures, including biopsies, invasive endoscopies, and imaging, with one undergoing eight differential diagnoses that were ruled out through additional testing. Recalcitrant cytopenias, a history of infection, and a family history of lymphoproliferation, infection, or autoimmunity raised suspicion of an underlying IEI, leading to genetic testing. Genetic testing identified a pathogenic variant of PIK3CD in each patient, resulting in the diagnosis of APDS. Following these diagnoses, two patients underwent modifications in the management of care with the administration of intravenous immunoglobulin therapy (IVIG), the mTOR inhibitor sirolimus, or surgical procedures. These treatment modifications either improved or resolved the cytopenias. The third patient showed improvement in immune thrombocytopenia with IVIG 1 month prior to receiving a definitive diagnosis. Following diagnosis, follow-up genetic testing of family members led to the identification of additional cases of APDS.

Conclusions

These cases highlight the importance of early genetic evaluation in patients with early-onset or recalcitrant cytopenias and demonstrate the challenges of differential diagnosis. In addition, these cases demonstrate beneficial changes in management and outcomes that can follow a definitive diagnosis, including the identification of targeted treatment options. Collectively, this case series supports the notion that underlying IEIs should be considered in the workup of early-onset or recalcitrant cytopenias, particularly in patients who present with a combination of hematologic and immunologic manifestations that are refractory to treatment, manifest at an unusually young age, or can be tied to family history.

Hyperactivation of the PI3K pathway in inborn errors of immunity: current understanding and therapeutic perspectives

The phosphoinositide-3-kinase (PI3K) pathway function is crucial to the normal development, differentiation, and function of immune cells including B, T, and NK cells. Following the description of two cohorts of patients with an inboirn error of immunity (also known as primary immunodeficiency) with gain-of-function variants in the PIK3CD gene a decade ago, the disease entity activated PI3K delta syndrome (APDS) was named. Since then, many more patients with PIK3CD variants have been described, and loss-of-function variants in PIK3R1 and PTEN have also been linked to APDS. Importantly, the availability of small molecules that inhibit the PI3K pathway has enabled targeted treatment of APDS patients. In this review, we define (i) the PI3K pathway and its role in inborn errors of immunity; (ii) the clinical and immunological presentation of APDS1 (PIK3CD GOF), APDS2 (PIK3R1 LOF), and related disorders; (iii) Diagnostic approaches to identify and functionally validate the genetic causes of disease; (iv) therapeutic interventions to target PI3K hyperactivation; and finally (v) current challenges and future perspectives that require attention for the optimal treatment of patients with APDS and APDS-L diseases.

Evaluation and treatment of rhinosinusitis with primary antibody deficiency in children: Evidence-based review with recommendations

BACKGROUND

There is clear evidence that prevalence of primary antibody deficiency (PAD) is higher in children with chronic rhinosinusitis (CRS) than in the general population. The purpose of this multi-institutional and multidisciplinary evidence-based review with recommendations (EBRR) is to thoroughly review the literature on rhinosinusitis with PAD, summarize the existing evidence, and provide recommendations on the evaluation and management of rhinosinusitis in children with PAD.

METHODS

The PubMed, Embase, and Cochrane databases were systematically reviewed from inception through December 2023. Studies on the evaluation and management of rhinosinusitis in PAD patients were included. An iterative review process was utilized in accordance with EBRR guidelines. Levels of evidence and recommendations on the evaluation and management principles for PAD were generated.

RESULTS

A total of 50 studies were included in this evidence-based review. These studies were evaluated on the incidence of PAD in rhinosinusitis patients, the incidence of rhinosinusitis in PAD patients, and on the different treatment modalities used and their outcome. The aggregate quality of evidence varied across the reviewed domains.

CONCLUSION

Based on the currently available evidence, the incidence of PAD in children with recalcitrant CRS can be significantly elevated. Despite the presence of multiple studies addressing rhinosinusitis and PAD, the level of evidence supporting different treatment options continues to be lacking. Optimal management requires a multidisciplinary approach through collaboration with clinical immunology. There is need for higher level studies that compare different treatments in children with PAD and rhinosinusitis.

A unified metric of human immune health

Immunological health has been challenging to characterize but could be defined as the absence of immune pathology. While shared features of some immune diseases and the concept of immunologic resilience based on age-independent adaptation to antigenic stimulation have been developed, general metrics of immune health and its utility for assessing clinically healthy individuals remain ill defined. Here we integrated transcriptomics, serum protein, peripheral immune cell frequency and clinical data from 228 patients with 22 monogenic conditions impacting key immunological pathways together with 42 age- and sex-matched healthy controls. Despite the high penetrance of monogenic lesions, differences between individuals in diverse immune parameters tended to dominate over those attributable to disease conditions or medication use. Unsupervised or supervised machine learning independently identified a score that distinguished healthy participants from patients with monogenic diseases, thus suggesting a quantitative immune health metric (IHM). In ten independent datasets, the IHM discriminated healthy from polygenic autoimmune and inflammatory disease states, marked aging in clinically healthy individuals, tracked disease activities and treatment responses in both immunological and nonimmunological diseases, and predicted age-dependent antibody responses to immunizations with different vaccines. This discriminatory power goes beyond that of the classical inflammatory biomarkers C-reactive protein and interleukin-6. Thus, deviations from health in diverse conditions, including aging, have shared systemic immune consequences, and we provide a web platform for calculating the IHM for other datasets, which could empower precision medicine.

A single center experience on PI3K/AKT/MTOR signaling defects: Towards pathogenicity assessment for four novel defects

BACKGROUND

Phosphoinositide 3 kinases (PI3K) are lipid kinases expressed in lymphocytes/myeloid cells. PI3K/AKT/mTOR signaling defects present with recurrent infections, autoimmunity, lymphoproliferation, and agammaglobulinemia.

OBJECTIVE

To characterize the PI3K/AKT/mTOR pathway defects and perform pathway analyses to assess novel variant pathogenicity.

METHODS

We included 12 patients (heterozygous PIK3CD (n = 9) and PIK3R1 (n = 1) (activated PI3K delta syndrome (APDS) with gain-of-function mutations) and homozygous PIK3R1 variant (n = 2)), performed clinical/laboratory/genetic evaluation, and flow cytometric PI3K/AKT/mTOR pathway analyses.

RESULTS

Median age at onset of complaints was 17.5 months (3 months to 12 years) and at diagnosis was 15.7 years (2.5-37) in APDS. Median diagnostic delay was 12.9 years (1.6-27). Recurrent respiratory tract infections (90%), lymphoproliferation (70%), autoimmune/inflammatory findings (60%), and allergy (40%) were common in APDS. Recurrent viral infections were present in 4/10 and malignancy (non-Hodgkin lymphoma and testicular yolk sac tumor) was present in 2/10 in APDS. Low CD4+ T cells(5/8) with increased CD4+ effector memory (8/8) and CD4+ TEMRA cells (6/8) were present in the given number of APDS patients. We diagnosed tubulointerstitial nephritis, Langerhans cell histiocytosis, and late-onset congenital adrenal hyperplasia in APDS. Allergic findings, lymphoproliferation/malignancy, and high IgM were present in the APDS but not in PIK3R1 deficiency. Low IgM/IgG/CD19+ B cell counts were characteristic in patients with PIK3R1 homozygous loss-of function mutations.

CONCLUSION

Differential diagnosis with combined immunodeficiency and diseases of immune dysregulation make molecular genetic analysis crucial for diagnosing mTOR pathway defects. It is easy to differentiate APDS and homozygous PIK3R1 defects with specific laboratory features. Additionally, mTOR pathway functional analysis is a definitive diagnostic and pathogenicity assessment tool for novel APDS mutations.

PI3Kγ in B cells promotes antibody responses and generation of antibody-secreting cells

The differentiation of naive and memory B cells into antibody-secreting cells (ASCs) is a key feature of adaptive immunity. The requirement for phosphoinositide 3-kinase-delta (PI3Kδ) to support B cell biology has been investigated intensively; however, specific functions of the related phosphoinositide 3-kinase-gamma (PI3Kγ) complex in B lineage cells have not. In the present study, we report that PI3Kγ promotes robust antibody responses induced by T cell-dependent antigens. The inborn error of immunity caused by human deficiency in PI3Kγ results in broad humoral defects, prompting our investigation of roles for this kinase in antibody responses. Using mouse immunization models, we found that PI3Kγ functions cell intrinsically within activated B cells in a kinase activity-dependent manner to transduce signals required for the transcriptional program supporting differentiation of ASCs. Furthermore, ASC fate choice coincides with upregulation of PIK3CG expression and is impaired in the context of PI3Kγ disruption in naive B cells on in vitro CD40-/cytokine-driven activation, in memory B cells on toll-like receptor activation, or in human tonsillar organoids. Taken together, our study uncovers a fundamental role for PI3Kγ in supporting humoral immunity by integrating signals instructing commitment to the ASC fate.

Activated PI3Kδ Specifically Perturbs Mouse Regulatory T Cell Homeostasis and Function Leading to Immune Dysregulation

FOXP3+ regulatory T cells (Treg) are required for maintaining immune tolerance and preventing systemic autoimmunity. PI3Kδ is required for normal Treg development and function. However, the impacts of dysregulated PI3Kδ signaling on Treg function remain incompletely understood. In this study, we used a conditional mouse model of activated PI3Kδ syndrome to investigate the role of altered PI3Kδ signaling specifically within the Treg compartment. Activated mice expressing a PIK3CD gain-of-function mutation (aPIK3CD) specifically within the Treg compartment exhibited weight loss and evidence for chronic inflammation, as demonstrated by increased memory/effector CD4+ and CD8+ T cells with enhanced IFN-γ secretion, spontaneous germinal center responses, and production of broad-spectrum autoantibodies. Intriguingly, aPIK3CD facilitated Treg precursor development within the thymus and an increase in peripheral Treg numbers. Peripheral Treg, however, exhibited an altered phenotype, including increased PD-1 expression and reduced competitive fitness. Consistent with these findings, Treg-specific aPIK3CD mice mounted an elevated humoral response following immunization with a T cell-dependent Ag, which correlated with a decrease in follicular Treg. Taken together, these findings demonstrate that an optimal threshold of PI3Kδ activity is critical for Treg homeostasis and function, suggesting that PI3Kδ signaling in Treg might be therapeutically targeted to either augment or inhibit immune responses.

Flow cytometry-based diagnostic approach for inborn errors of immunity: experience from Algeria

Purpose

In this study, we retrospectively reviewed the use of flow cytometry (FCM) in the diagnosis of inborn errors of immunity (IEIs) at a single center in Algeria. Sharing insights into our practical experience, we present FCM based diagnostic approaches adapted to different clinical scenarios.

Methods

Between May 2017 and February 2024, pediatric and adult patients presenting with clinical features suggestive of immunodeficiency were subjected to FCM evaluation, including lymphocyte subset analysis, detection of specific surface or intracellular proteins, and functional analysis of immune cells.

Results

Over a nearly seven-year period, our laboratory diagnosed a total of 670 patients (372 (55.5%) males and 298 (44.5%) females), distributed into 70 different IEIs belonging to 9 different categories of the International Union of Immunological Societies classification. FCM was used to diagnose and categorize IEI in 514 patients (76.7%). It provided direct diagnostic insights for IEIs such as severe combined immunodeficiency, Omenn syndrome, MHC class II deficiency, familial hemophagocytic lymphohistiocytosis, and CD55 deficiency. For certain IEIs, including hyper-IgE syndrome, STAT1-gain of function, autoimmune lymphoproliferative syndrome, and activated PI3K delta syndrome, FCM offered suggestive evidence, necessitating subsequent genetic testing for confirmation. Protein expression and functional assays played a crucial role in establishing definitive diagnoses for various disorders. To setup such diagnostic assays at high and reproducible quality, high level of expertise is required; in house reference values need to be determined and the parallel testing of healthy controls is highly recommended.

Conclusion

Flow cytometry has emerged as a highly valuable and cost-effective tool for diagnosing and studying most IEIs, particularly in low-income countries where access to genetic testing can be limited. FCM analysis could provide direct diagnostic insights for most common IEIs, offer clues to the underlying genetic defects, and/or aid in narrowing the list of putative genes to be analyzed.

Genetic Evaluation of the Patients with Clinically Diagnosed Inborn Errors of Immunity by Whole Exome Sequencing: Results from a Specialized Research Center for Immunodeficiency in Türkiye

Molecular diagnosis of inborn errors of immunity (IEI) plays a critical role in determining patients' long-term prognosis, treatment options, and genetic counseling. Over the past decade, the broader utilization of next-generation sequencing (NGS) techniques in both research and clinical settings has facilitated the evaluation of a significant proportion of patients for gene variants associated with IEI. In addition to its role in diagnosing known gene defects, the application of high-throughput techniques such as targeted, exome, and genome sequencing has led to the identification of novel disease-causing genes. However, the results obtained from these different methods can vary depending on disease phenotypes or patient characteristics. In this study, we conducted whole-exome sequencing (WES) in a sizable cohort of IEI patients, consisting of 303 individuals from 21 different clinical immunology centers in Türkiye. Our analysis resulted in likely genetic diagnoses for 41.1% of the patients (122 out of 297), revealing 52 novel variants and uncovering potential new IEI genes in six patients. The significance of understanding outcomes across various IEI cohorts cannot be overstated, and we believe that our findings will make a valuable contribution to the existing literature and foster collaborative research between clinicians and basic science researchers.

Pathophysiology and genomics of bronchiectasis

Bronchiectasis is a complex and heterogeneous inflammatory chronic respiratory disease with an unknown cause in around 30-40% of patients. The presence of airway infection together with chronic inflammation, airway mucociliary dysfunction and lung damage are key components of the vicious vortex model that better describes its pathophysiology. Although bronchiectasis research has significantly increased over the past years and different endotypes have been identified, there are still major gaps in the understanding of the pathophysiology. Genomic approaches may help to identify new endotypes, as has been shown in other chronic airway diseases, such as COPD.Different studies have started to work in this direction, and significant contributions to the understanding of the microbiome and proteome diversity have been made in bronchiectasis in recent years. However, the systematic application of omics approaches to identify new molecular insights into the pathophysiology of bronchiectasis (endotypes) is still limited compared with other respiratory diseases.Given the complexity and diversity of these technologies, this review describes the key components of the pathophysiology of bronchiectasis and how genomics can be applied to increase our knowledge, including the study of new techniques such as proteomics, metabolomics and epigenomics. Furthermore, we propose that the novel concept of trained innate immunity, which is driven by microbiome exposures leading to epigenetic modifications, can complement our current understanding of the vicious vortex. Finally, we discuss the challenges, opportunities and implications of genomics application in clinical practice for better patient stratification into new therapies.

Long-term treatment with selective PI3Kδ inhibitor leniolisib in adults with activated PI3Kδ syndrome

ABSTRACT

Activated phosphoinositide 3-kinase delta (PI3Kδ) syndrome (APDS) is an inborn error of immunity that manifests as immune deficiency and dysregulation; symptoms include frequent infections and lymphoproliferation. In our dose-finding and phase 3 placebo-controlled trials, treatment with the selective PI3Kδ inhibitor leniolisib reduced lymphoproliferation and normalized lymphocyte subsets. Here, we present 6 years of follow-up from the 6 adult patients in the original dose-finding trial receiving leniolisib. We used data from the ongoing open-label extension study, which was supplemented at later time points by investigators, including health-related quality of life (HRQoL) assessed through a clinician-reported questionnaire. We observed improvements in HRQoL: 5 of 6 patients experienced an increase in physical capabilities and socialization, and a decrease in prescribed medications. Immune subsets improved in all patients: mean transitional B-cell levels decreased from 38.17% to 2.47% and the CD4:CD8 T-cell ratio normalized to 1.11. Manifestations seen before and within the first year of leniolisib exposure, such as infections and gastrointestinal conditions, attenuated after year 2, with few new conditions emerging out to year 6. Thrombocytopenia or lymphopenia remained present in half of patients at year 6. Of 83 adverse events through year 5, 90.36% were grade 1; none were grade 4/5 nor deemed leniolisib related. Collectively, we saw an enhancement in HRQoL as well as durable changes in lymphocyte subsets and clinical manifestations, further supporting the use of leniolisib as a long-term therapeutic option for the treatment of APDS. This trial was registered at www.ClinicalTrials.gov as #NCT02859727.

Activated phosphoinositde 3-kinase (PI3Kδ) syndrome: an Italian point of view on diagnosis and new advances in treatment

Activated phosphoinositide 3-kinase (PI3Kδ) Syndrome (APDS) is an inborn error of immunity (IEI) with a variable clinical presentation, characterized by infection susceptibility and immune dysregulation that may overlaps with other Primary Immune Regulatory Disorders (PIRDs). The rarity of the disease, its recent discovery, and the multiform /multifaced clinical presentation make it difficult to establish a correct diagnosis, especially at an early stage. As a result, the true prevalence of the pathology remains unknown. There is no treatment protocol for APDS, and drug therapy is primarily focused on treating symptoms. The most common therapies include immunoglobulin replacement therapy, antimicrobial prophylaxis, and immunosuppressive drugs. Hematopoietic stem cell transplantation (HSCT) has been used in some cases, but the risk-benefit balance remains unclear. With the upcoming introduction of specific medications, such as selective inhibitors for PI3Kδ, clinicians are shifting their attention towards target therapy.This review provides a comprehensive overview of APDS with a focus on diagnostic and treatments procedures available. This review may be useful in implementing strategies for a more efficient patients' management and therapeutic interventions.Main Text.

A qualitative study to explore the burden of disease in activated phosphoinositide 3-kinase delta syndrome (APDS)

BACKGROUND

Activated phosphoinositide 3-kinase delta syndrome (APDS) is an ultra-rare primary immunodeficiency, with only 256 cases reported globally. This study aimed to explore the disease burden of APDS from the perspective of individuals with APDS and their caregivers.

METHODS

Qualitative interviews were conducted with healthcare providers (HCPs), individuals with APDS and caregivers, to explore the symptoms and health-related quality of life (HRQoL) impact of APDS. Some individuals and caregivers also completed a narrative account exercise. All interviews were audio recorded and transcribed. Data were analysed using thematic analysis and saturation was recorded.

RESULTS

Semi-structured qualitative interviews were conducted with healthcare providers (HCPs), individuals with APDS and caregivers. Individuals and caregivers had the option of completing a narrative account exercise. Six HCPs participated in an interview. Seven participants completed the narrative account exercise (N = 5 caregivers and N = 2 individuals with APDS) and 12 took part in an interview (N = 4 caregivers and N = 8 individuals with APDS). Themes identified from HCPs interviews included symptoms, clinical manifestations, HRQoL impacts and treatments/management of APDS. The narrative account exercise identified similar themes, but with the addition to the journey to diagnosis. These themes were explored during the individual/caregiver interviews. Reported clinical manifestations and symptoms of APDS included susceptibility to infections, lymphoproliferation, gastrointestinal (GI) disorders, fatigue, bodily pain, and breathing difficulties. HRQoL impacts of living with APDS included negative impacts to daily activities, including work, education and social and leisure activities, physical functioning, as well as emotional well-being, such as concern for the future, and interpersonal relationships. Impacts to caregiver HRQoL included negative impacts to physical health, work, emotional well-being, interpersonal relationships and family life and holidays. The management of APDS included the use of healthcare services and medications including immunoglobulin replacement therapy (IRT), rapamycin, prophylactic antibiotics, leniolisib, as well as medical procedures due to complications.

CONCLUSIONS

APDS has a high disease burden and there is an unmet need for licensed, more targeted treatments which modify disease progression. This study was the first to describe the day-to-day experience and HRQoL impact of APDS from the perspective of individuals living with the condition, caregivers and treating physicians.

[Activated phosphoinositide 3-kinase delta syndrome: report of seven cases]

OBJECTIVES

To summarize the clinical data of 7 children with activated phosphoinositide 3-kinase delta syndrome (APDS) and enhance understanding of the disease.

METHODS

A retrospective analysis was conducted on clinical data of 7 APDS children admitted to Hunan Provincial People's Hospital from January 2019 to August 2023.

RESULTS

Among the 7 children (4 males, 3 females), the median age of onset was 30 months, and the median age at diagnosis was 101 months. Recurrent respiratory tract infections, hepatosplenomegaly, and multiple lymphadenopathy were observed in all 7 cases. Sepsis was observed in 5 cases, otitis media and multiple caries were observed in 3 cases, and diarrhea and joint pain were observed in 2 cases. Lymphoma and systemic lupus erythematosus were observed in 1 case each. Fiberoptic bronchoscopy was performed in 4 cases, revealing scattered nodular protrusions in the bronchial lumen. The most common respiratory pathogen was Streptococcus pneumoniae (4 cases). Six patients had a p.E1021K missense mutation, and one had a p.434-475del splice site mutation.

CONCLUSIONS

p.E1021K is the most common mutation site in APDS children. Children who present with one or more of the following symptoms: recurrent respiratory tract infections, hepatosplenomegaly, multiple lymphadenopathy, otitis media, and caries, and exhibit scattered nodular protrusions on fiberoptic bronchoscopy, should be vigilant for APDS. Citation:Chinese Journal of Contemporary Pediatrics, 2024, 26(5): 499-505.

Autoimmune cytopenia and Kabuki syndrome in paediatrics: Insights in 11 patients

Kabuki syndrome (KS) is now listed in the Human Inborn Errors of Immunity (IEI) Classification. It is a rare disease caused by KMT2D and KDM6A variants, dominated by intellectual disability and characteristic facial features. Recurrently, pathogenic variants are identified in those genes in patients examined for autoimmune cytopenia (AIC), but interpretation remains challenging. This study aims to describe the genetic diagnosis and the clinical management of patients with paediatric-onset AIC and KS. Among 11 patients with AIC and KS, all had chronic immune thrombocytopenic purpura, and seven had Evans syndrome. All had other associated immunopathological manifestations, mainly symptomatic hypogammaglobinaemia. They had a median of 8 (5-10) KS-associated manifestations. Pathogenic variants were detected in KMT2D gene without clustering, during the immunological work-up of AIC in three cases, and the clinical strategy to validate them is emphasized. Eight patients received second-line treatments, mainly rituximab and mycophenolate mofetil. With a median follow-up of 17 (2-31) years, 8/10 alive patients still needed treatment for AIC. First-line paediatricians should be able to recognize and confirm KS in children with ITP or multiple AIC, to provide early appropriate clinical management and specific long-term follow-up. The epigenetic immune dysregulation in KS opens exciting new perspectives.

Phenotypic and Immunological Characterization of Patients with Activated PI3Kδ Syndrome 1 Presenting with Autoimmunity

PURPOSE

Autoimmunity is a significant feature of APDS1 patients. We aimed to explore the pathogenic immune phenotype and possible mechanisms of autoimmunity in APDS1 patients.

METHODS

The clinical records and laboratory data of 42 APDS1 patients were reviewed. Immunophenotypes were evaluated by multiparametric flow cytometry. Autoantibodies were detected via antigen microarray analysis.

RESULTS

A total of 42 children with PIK3CD gene mutations were enrolled. Immunological tests revealed increased proportions of effector memory cells (86%) and central memory cells (59%) among CD4+ T cells; increased proportions of effector memory cells (83%) and terminally differentiated effector memory T cells (38%) among CD8+ T cells. Fewer CD3+ T cells and B cells and higher IgG levels were reported in patients with autoimmunity. The proportion of Tregs was decreased, and the proportions of Th9, Tfh, and Tfr cells were increased in APDS1 patients. Among APDS1 patients, higher proportion of Th2 and Tfr cells were found in those with autoimmunity. The proportions of CD11c+ B and CD21lo B cells in patients with autoimmunity were significantly increased. Antigen microarray analysis revealed a wide range of IgG/IgM autoantibodies in patients with APDS1. In patients with autoimmunity, the proportion of Tfr might be positively correlated with autoantibodies.

CONCLUSIONS

The pathogenic immune phenotype of APDS1 patients included (1) deceased CD3+ T-cell and B-cell counts and increased IgG levels in patients with autoimmunity, (2) an imbalanced T helper cell subset, (3) increased proportions of autoreactive B cells, and (4) distinct autoantibody reactivities in patients with autoimmunity.

The Dark Side of Activated Phosphoinositide 3-Kinase-δ Syndrome 2: A Story Rewritten through FDG-PET

Background: Activated phosphoinositide 3-kinase-δ syndrome 2 (APDS2) is characterized by lymphoproliferation and increased risk of malignancy. FDG-PET/CT may represent a helpful diagnostic tool for differentiating these clinical features and correctly diagnosing inborn errors of immunity (IEI). Case report: We present the case of a female patient diagnosed with Hodgkin's lymphoma at 19 years of age, although atypical imaging aspects emerged: baseline FDG-PET/CT revealed several hot lymph nodes with a symmetrical distribution, and increased tracer uptake in spleen, axial, and appendicular bone marrow. Imaging repeated after chemotherapy and autologous stem cell transplantation showed persistent increased FDG uptake at multiple supradiaphragmatic nodes and in bone marrow. After the diagnosis of APDS2 and rapamycin treatment, FDG-PET/CT confirmed complete metabolic normalization of all sites. Conclusions: In the IEI scenario, FDG-PET/CT plays an effective role in differentiating malignant proliferation and immune dysregulation phenotypes. Atypical patterns at FDG-PET/CT should be interpreted as a red flag for the need of an early immunological evaluation.

Failed Downregulation of PI3K Signaling Makes Autoreactive B Cells Receptive to Bystander T Cell Help

The role of T cell help in autoantibody responses is not well understood. Because tolerance mechanisms govern both T and B cell responses, one might predict that both T cell tolerance and B cell tolerance must be defeated in autoantibody responses requiring T cell help. To define whether autoreactive B cells depend on T cells to generate autoantibody responses, we studied the role of T cells in murine autoantibody responses resulting from acute B cell-specific deletion of regulatory phosphatases. Ars/A1 B cells are DNA reactive and require continuous inhibitory signaling by the tyrosine phosphatase SHP-1 and the inositol phosphatases SHIP-1 and PTEN to maintain unresponsiveness. Acute B cell-restricted deletion of any of these phosphatases results in an autoantibody response. In this study, we show that CD40-CD40L interactions are required to support autoantibody responses of B cells whose anergy has been compromised. If the B cell-intrinsic driver of loss of tolerance is failed negative regulation of PI3K signaling, bystander T cells provide sufficient CD40-mediated signal 2 to support an autoantibody response. However, although autoantibody responses driven by acute B cell-targeted deletion of SHP-1 also require T cells, bystander T cell help does not suffice. These results demonstrate that upregulation of PI3K signaling in autoreactive B cells, recapitulating the effect of multiple autoimmunity risk alleles, promotes autoantibody responses both by increasing B cells' cooperation with noncognate T cell help and by altering BCR signaling. Receptiveness to bystander T cell help enables autoreactive B cells to circumvent the fail-safe of T cell tolerance.

Infections in Disorders of Immune Regulation

Primary immune regulatory disorders (PIRDs) constitute a spectrum of inborn errors of immunity (IEIs) that are primarily characterized by autoimmunity, lymphoproliferation, atopy, and malignancy. In PIRDs, infections are infrequent compared to other IEIs. While susceptibility to infection primarily stems from antibody deficiency, it is sometimes associated with additional innate immune and T or NK cell defects. The use of immunotherapy and chemotherapy further complicates the immune landscape, increasing the risk of diverse infections. Recurrent sinopulmonary infections, particularly bacterial infections such as those associated with staphylococcal and streptococcal organisms, are the most reported infectious manifestations. Predisposition to viral infections, especially Epstein-Barr virus (EBV)-inducing lymphoproliferation and malignancy, is also seen. Notably, mycobacterial and invasive fungal infections are rarely documented in these disorders. Knowledge about the spectrum of infections in these disorders would prevent diagnostic delays and prevent organ damage. This review delves into the infection profile specific to autoimmune lymphoproliferative syndrome (ALPS), Tregopathies, and syndromes with autoimmunity within the broader context of PIRD. Despite the critical importance of understanding the infectious aspects of these disorders, there remains a scarcity of comprehensive reports on this subject.

Leniolisib: a novel treatment for activated phosphoinositide-3 kinase delta syndrome

IC50 = 11 nM (PI3Kδ); 244 nM (PI3Kα); 424 nM (PI3Kβ), 2,230 nM (PI3Kγ).

Monogenic etiologies of persistent human papillomavirus infections: A comprehensive systematic review

PURPOSE

Persistent human papillomavirus infection (PHPVI) causes cutaneous, anogenital, and mucosal warts. Cutaneous warts include common warts, Treeman syndrome, and epidermodysplasia verruciformis, among others. Although more reports of monogenic predisposition to PHPVI have been published with the development of genomic technologies, genetic testing is rarely incorporated into clinical assessments. To encourage broader molecular testing, we compiled a list of the various monogenic etiologies of PHPVI.

METHODS

We conducted a systematic literature review to determine the genetic, immunological, and clinical characteristics of patients with PHPVI.

RESULTS

The inclusion criteria were met by 261 of 40,687 articles. In 842 patients, 83 PHPVI-associated genes were identified, including 42, 6, and 35 genes with strong, moderate, and weak evidence for causality, respectively. Autosomal recessive inheritance predominated (69%). PHPVI onset age was 10.8 ± 8.6 years, with an interquartile range of 5 to 14 years. GATA2,IL2RG,DOCK8, CXCR4, TMC6, TMC8, and CIB1 are the most frequently reported PHPVI-associated genes with strong causality. Most genes (74 out of 83) belong to a catalog of 485 inborn errors of immunity-related genes, and 40 genes (54%) are represented in the nonsyndromic and syndromic combined immunodeficiency categories.

CONCLUSION

PHPVI has at least 83 monogenic etiologies and a genetic diagnosis is essential for effective management.

A combined opposite targeting of p110δ PI3K and RhoA abrogates skin cancer

Malignant melanoma is the most aggressive and deadly skin cancer with an increasing incidence worldwide whereas SCC is the second most common non-melanoma human skin cancer with limited treatment options. Here we show that the development and metastasis of melanoma and SCC cancers can be blocked by a combined opposite targeting of RhoA and p110δ PI3K. We found that a targeted induction of RhoA activity into tumours by deletion of p190RhoGAP-a potent inhibitor of RhoA GTPase-in tumour cells together with adoptive macrophages transfer from δD910A/D910A mice in mice bearing tumours with active RhoA abrogated growth progression of melanoma and SCC tumours. Τhe efficacy of this combined treatment is the same in tumours lacking activating mutations in BRAF and in tumours harbouring the most frequent BRAF(V600E) mutation. Furthermore, the efficiency of this combined treatment is associated with decreased ATX expression in tumour cells and tumour stroma bypassing a positive feedback expression of ATX induced by direct ATX pharmacological inactivation. Together, our findings highlight the importance of targeting cancer cells and macrophages for skin cancer therapy, emerge a reverse link between ATX and RhoA and illustrate the benefit of p110δ PI3K inhibition as a combinatorial regimen for the treatment of skin cancers.

PI3Kδ Pathway Dysregulation and Unique Features of Its Inhibition by Leniolisib in Activated PI3Kδ Syndrome and Beyond

The phosphoinositide 3-kinase (PI3K) pathway regulates diverse cellular processes, with finely tuned PI3Kδ activity being crucial for immune cell development and function. Genetic hyperactivation of PI3Kδ causes the inborn error of immunity activated phosphoinositide 3-kinase δ syndrome (APDS). Several PI3Kδ inhibitors have been investigated as treatment options for APDS, but only leniolisib has shown both efficacy and tolerability. In contrast, severe immune-mediated adverse events such as colitis, neutropenia, and hepatotoxicity have been observed with other PI3Kδ inhibitors, particularly those indicated for hematological malignancies. We propose that leniolisib is distinguished from other PI3Kδ inhibitors due to its structure, specific inhibitory properties selectively targeting the δ isoform without overinhibition of the δ or γ isoforms, and the precise match between APDS mechanism of disease and drug mechanism of action.

Interim analysis: Open-label extension study of leniolisib for patients with APDS

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.

Determining value in the treatment of activated PI3Kδ syndrome in Spain: a multicriteria decision analysis from the perspective of key stakeholders

Introduction

Activated phosphoinositide 3-kinase (PI3K)δ syndrome (APDS) is an ultra-rare inborn error of immunity (IEI) combining immunodeficiency and immune dysregulation. This study determined what represents value in APDS in Spain from a multidisciplinary perspective applying multicriteria decision analysis (MCDA) methodology.

Methods

A multidisciplinary committee of nine experts scored the evidence matrix. A specific framework for orphan drug evaluation in Spain and the weights assigned by a panel of 98 evaluators and decision-makers was used. Re-evaluation of scores was performed.

Results

APDS is considered a very severe disease with important unmet needs, including misdiagnosis and diagnostic delay. Current management is limited to treatment of symptoms with off-label use of therapies supported by limited evidence. Therapeutic benefit is partial, resulting in limited disease control. Haematopoietic stem cell transplantation (HSCT), the only potential curative alternative, is restricted to a reduced patient population and without evidence of long-term efficacy or safety. All options present a limited safety profile. Data on patients' quality of life are lacking. APDS is associated with high pharmacological, medical and indirect costs.

Conclusions

APDS is considered a severe disease, with limited understanding by key stakeholders of how treatment success is assessed in clinical practice, the serious impact that has on patients and the associated high economic burden. This study brings to light how MCDA methodology could represent a useful tool to complement current clinical and decision-making methods used by APDS experts and evaluators.

Modulating the PI3K Signalling Pathway in Activated PI3K Delta Syndrome: a Clinical Perspective

Activated phosphoinositide-3-kinase (PI3K) δ syndrome (APDS) is an inborn error of immunity characterised by immune dysregulation. Since the discovery of genetic mutations resulting in PI3Kδ overactivation, treatment of APDS patients has begun to focus on modulation of the PI3K pathway in addition to supportive therapies. The mTOR inhibitor sirolimus has been used effectively for some clinical manifestations of this condition, however the arrival of specific PI3Kδ inhibitor leniolisib has shown promising early results and may provide a more targeted approach. This review summarizes key aspects of PI3K pathway biology and discusses potential options for nuanced modulation of the PI3K pathway in APDS from a clinical perspective, highlighting differences from PI3K inhibition in haematological malignancies.

Activated PI3Kδ specifically perturbs mouse Treg homeostasis and function leading to immune dysregulation

Foxp3+ regulatory T cells (Treg) are required for maintaining immune tolerance and preventing systemic autoimmunity. PI3Kδ is required for normal Treg development and function. However, the impacts of dysregulated PI3Kδ signaling on Treg function remain incompletely understood. Here, we used a conditional mouse model of activated PI3Kδ syndrome (APDS) to investigate the role of altered PI3Kδ signaling specifically within the Treg compartment. Aged mice expressing a PIK3CD gain-of-function mutation (aPIK3CD) specifically within the Treg compartment exhibited weight loss and evidence for chronic inflammation as demonstrated by increased memory/effector CD4+ and CD8+ T cells with enhanced IFN-γ secretion, spontaneous germinal center responses and production of broad-spectrum autoantibodies. Intriguingly, aPIK3CD facilitated Treg precursor development within the thymus and an increase in peripheral Treg numbers. Peripheral Treg, however, exhibited an altered phenotype including increased PD1 expression and reduced competitive fitness. Consistent with these findings, Treg specific-aPIK3CD mice mounted an elevated humoral response following immunization with a T-cell dependent antigen, that correlated with a decrease in follicular Treg. Taken together, these findings demonstrate that an optimal threshold of PI3Kδ activity is critical for Treg homeostasis and function, suggesting that PI3Kδ signaling in Treg might be therapeutically targeted to either augment or inhibit immune responses.

Hematopoietic stem cell transplantation in a patient with activated phosphoinositide 3-kinase δ syndrome: A case report and literature review

Activated phosphoinositide 3-kinase δ syndrome (APDS) is a recently described disease characterized by recurrent infections, lymphoproliferation with a high risk of malignancy, early-onset cytopenia, and a propensity for autoimmune diseases. Hematopoietic stem cell transplantation (HSCT) has proven to be an effective treatment method; however, the recovery process after HSCT is prolonged and accompanied by complications. In this study, we present the case of a patient with APDS type 1. Despite showing signs of immunodeficiency at the age of 6 months, it took almost 6 years to reach a definitive diagnosis. The patient experienced recurrent infections, often accompanied by anemia requiring transfusions, and multifocal nonmalignant lymphoproliferation. Only after receiving the appropriate diagnosis was it possible to implement proper and accurate treatment. HSCT was performed when the patient was 6 years old, leading to significant improvement in his condition. At the 17-month post-HSCT follow-up, the boy is asymptomatic and in good general health, although close monitoring continues due to mixed chimerism and delayed humoral immune recovery. Applying HSCT before the patient develops malignancy contributes to expanding the use of HSCT as a treatment option for APDS type 1.

Rescuing the cytolytic function of APDS1 patient T cells via TALEN-mediated PIK3CD gene correction

Gain-of-function mutations in the PIK3CD gene result in activated phosphoinositide 3-kinase δ syndrome type 1 (APDS1). This syndrome is a life-threatening combined immunodeficiency and today there are neither optimal nor long-term therapeutic solutions for APDS1 patients. Thus, new alternative treatments are highly needed. The aim of the present study is to explore one therapeutic avenue that consists of the correction of the PIK3CD gene through gene editing. Our proof-of-concept shows that TALEN-mediated gene correction of the mutated PIK3CD gene in APDS1 T cells results in normalized phospho-AKT levels in basal and activated conditions. Normalization of PI3K signaling was correlated to restored cytotoxic functions of edited CD8+ T cells. At the transcriptomic level, single-cell RNA sequencing revealed corrected signatures of CD8+ effector memory and CD8+ proliferating T cells. This proof-of-concept study paves the way for the future development of a gene therapy candidate to cure activated phosphoinositide 3-kinase δ syndrome type 1.

Monogenic forms of common variable immunodeficiency and implications on target therapeutic approaches

PURPOSE OF REVIEW

Common variable immunodeficiency (CVID) is the most common symptomatic inborn error of immunity. The disorder is characterized by variable clinical and immunological manifestations, and, in a small minority of patients, a monogenic cause may be identified. In this review, we focalized on three different monogenic forms of CVID-like disease.

RECENT FINDINGS

Activated phosphoinositide 3-kinase delta syndrome (APDS) is a rare disorder characterized by hyperactivated class I phosphatidylinositol-3 kinase (PI3K) pathway. Affected patients present with respiratory infectious episodes, impaired viral clearance and lymphoproliferation. Recently, a direct PI3K inhibitor has been approved and it showed encouraging results both in controlling clinical and immunological manifestations of the disease. On the other hand, patients with defects in CTLA-4 or LRBA gene present with life-threatening immune dysregulation, autoimmunity and lymphocytic infiltration of multiple organs. Abatacept, a soluble cytotoxic T lymphocyte antigen 4 (CTLA-4) fusion protein that acts as a costimulation modulator, has been widely implemented for affected patients with good results as bridge treatment.

SUMMARY

Understanding the biological basis of CVID is important not only for enriching our knowledge of the human immune system, but also for setting the basis for potential targeted treatments in this disorder.

Clinical practice guideline for activated phosphatidyl inositol 3-kinase-delta syndrome in Japan

Activated phosphatidyl inositol 3-kinase-delta syndrome (APDS) due to gain-of-function variant in the class IA PI3K catalytic subunit p110δ (responsible gene: PIK3CD) was described in 2013. The disease is characterized by recurrent airway infections and bronchiectasis. It is associated with hyper-IgM syndrome due to the defect of immunoglobulin class switch recombination and decreased CD27-positive memory B cells. Patients also suffered from immune dysregulations, such as lymphadenopathy, autoimmune cytopenia or enteropathy. T-cell dysfunction due to increased senescence is associated with a decrease in CD4-positive T lymphocytes and CD45RA-positive naive T lymphocytes, along with increased susceptibility to Epstein-Barr virus/cytomegalovirus infections. In 2014, loss-of-function (LOF) mutation of p85α (responsible gene: PIK3R1), a regulatory subunit of p110δ, was identified as a causative gene, followed in 2016 by the identification of the LOF mutation of PTEN, which dephosphorylates PIP3, leading to the differentiation of APDS1 (PIK3CD-GOF), APDS2 (PIK3R1-LOF) and APDS-L (PTEN-LOF). Since the pathophysiology of patients with APDS varies with a wide range of severity, it is crucial that patients receive appropriate treatment and management. Our research group created a disease outline and a diagnostic flow chart and summarized clinical information such as the severity classification of APDS and treatment options.