PIK3CA-related Overgrowth Syndrome Research Articles

Genetic insights into the mechanisms of proliferative glomerulonephritis.

Glomerular visceral epithelial cells (i.e., podocytes) are an essential component of the tripartite glomerular filtration barrier. Healthy podocytes are terminally differentiated cells with limited replicative capacity; however, inappropriate cell cycle reentry can be induced in podocytes by various injurious stimuli. In this issue of the JCI, Yamaguchi et al. report on a somatic mosaic gain-of-function mutation in the phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic α subunit (p110α, encoded by PIK3CA). The study reveals that activating mutations of p110α can drive podocyte proliferation in PIK3CA-related overgrowth syndrome (PROS). They also showed that selective, small-molecule inhibitors of p110 may be useful for the treatment of proliferative glomerulonephritis.

PIK3CA gain-of-function mutation in adipose tissue induces metabolic reprogramming with Warburg-like effect and severe endocrine disruption.

PIK3CA-related overgrowth syndrome (PROS) is a genetic disorder caused by somatic mosaic gain-of-function mutations of PIK3CA. Clinical presentation of patients is diverse and associated with endocrine disruption. Adipose tissue is frequently involved, but its role in disease development and progression has not been elucidated. Here, we created a mouse model of PIK3CA-related adipose tissue overgrowth that recapitulates patient phenotype. We demonstrate that PIK3CA mutation leads to GLUT4 membrane accumulation with a negative feedback loop on insulin secretion, a burst of liver IGFBP1 synthesis with IGF-1 sequestration, and low circulating levels. Mouse phenotype was mainly driven through AKT2. We also observed that PIK3CA mutation induces metabolic reprogramming with Warburg-like effect and protein and lipid synthesis, hallmarks of cancer cells, in vitro, in vivo, and in patients. We lastly show that alpelisib is efficient at preventing and improving PIK3CA-adipose tissue overgrowth and reversing metabolomic anomalies in both animal models and patients.

Clinical and genetic analyses of patients with lateralized overgrowth

BackgroundThe genetic features and treatment strategies of lateralized overgrowth have been elusive. We performed this study to analyze the genetic characteristics and treatment results of propranolol- or alpelisib-treated patients with lateralized overgrowth.MethodsFifteen patients with lateralized overgrowth were involved. Clinical characteristics and whole-body magnetic resonance imaging (WB-MRI) findings were evaluated. Targeted exome sequencing with a gene panel of affected tissue and peripheral white blood cells was performed. Propranolol was administered and treatment results were evaluated. The PIK3CA inhibitor alpelisib was prescribed via a managed access program.ResultsThe identified mutations were PIK3CA (n = 7), KRAS (n = 2), PTEN (n = 1), MAP2K3 (n = 1), GNAQ (n = 1), TBC1D4 (n = 1), and TEK (n = 1). Propranolol was prescribed in 12 patients, and 7 experienced mild improvement of symptoms. Alpelisib was prescribed in two patients with a PIK3CA mutation, and the reduction of proliferated masses after 1 year of treatment was proved by WB-MRI.ConclusionsTargeted exome sequencing identified various genetic features of lateralized overgrowth. Propranolol could be applied as an adjuvant therapy for reducing vascular symptoms, but a PIK3CA inhibitor would be the primary therapeutic strategy for PIK3CA-related overgrowth syndrome.

Early diagnosis enabling precision medicine treatment in a young boy with PIK3R1-related overgrowth

Mosaic PIK3R1 variants have recently been demonstrated in patients with complex vascular malformations and overgrowth in a syndrome resembling PIK3CA-related overgrowth syndrome (PROS). The PIK3CA-inhibitor, alpelisib, seems to be a promising treatment option for PROS patients. We describe a young boy with overgrowth and a pathogenic mosaic variant in PIK3R1; c.1699A > G, p.(Lys567Glu). He was prenatally suspected of a syndrome on the presence of unusual transient fluctuating subcutaneous edemas and lymphedema of his left shoulder. The pathogenic variant, later found to be causative, was below detection threshold in whole-genome sequencing (WGS) analysis of amniotic fluid. Upon delivery a mosaic pathogenic PIK3R1 variant, was identified by whole-exome sequencing (WES) of a skin biopsy. With no proven treatment options available, and based on the theoretical disease mechanism, alpelisib therapy was initiated at nine months of age. In the first year of treatment growth normalized and the affected vascular and lymphatic tissue regressed. No side effects have been observed. This report underlines the importance of early variant detection in children suspected of having severe mosaic overgrowth, and proves that prenatal diagnosis is possible, enabling prompt treatment. Furthermore, it demonstrates the promising effects of alpelisib in this patient group.

Undergrowth Of First Toe In PiK3CA-Related Overgrowth Spectrum (PROS)

PIK3CA-related overgrowth syndrome (PROS) include a heterogeneous group of disorders characterized by segmental overgrowth secondary to somatic mosaic activating variants in PIK3CA. Segmental undergrowth is more uncommon and has been less studied but pathogenic variants in PIK3CA have also been found. With this in mind, we have noticed a group of patients with PROS that present an undergrowth component associated with their focal overgrowth. Retrospective review of patients with PROS presenting overgrowth of the lower limb and undergrowth of the ipsilateral first toe was performed. Six patients were included, 4 female and 2 male with a median age of 16.8years. All patients presented a PROS phenotype with overgrowth of the lower limb and undergrowth of ipsilateral first toe. A PIK3CA pathogenic variant was confirmed in all patients. Patients underwent multiple treatments, currently all are receiving alpelisib with a mean duration of 15.8months (1-39) and partial response in lipomatosis and vascular anomalies but no response in overgrowth and undergrowth so far. Pathogenic variants in the same gene can create different phenotypes depending on the time and place of the mutation. There is little information regarding opposing phenotpyes in the same patient with PROS. The presence of undergrowth in our series might be explained by genetic, embryogenic, maternal, or placental factors but needs to be further investigated.

The Klippel-Trénaunay Syndrome in 2022: Unravelling Its Genetic and Molecular Profile and Its Link to the Limb Overgrowth Syndromes.

The Klippel-Trénaunay syndrome is an unusual syndrome of vascular and dermatologic manifestation in which patients demonstrate hemihypertrophy of the soft tissue and bones of one limb, cutaneous haemangiomas and varicosities in anatomically abnormal positions. Described in 1900 by two French physicians, the etiology remained unclear until recently, when evidence emerged that there was a genetic basis for this sporadic disorder. Genes that encoded pathological angiogenic factors and caused vascular dysmorphogenesis, explaining the molecular bases of this syndrome, were identified. Several angiogenic genes were identified but one gene, the AGGF1 (formerly VG5Q) gene, was seen in mutations involving patients diagnosed with Klippel-Trénaunay syndrome. Furthermore, this syndrome was also noted to have overlapping clinical features linked with the “overgrowth syndromes,” in which genetic mutations along somatic lines were identified. These involved The PI3K enzyme which forms part of the phosphoinositide 3–kinase pathway which is encoded by the PIK3CA-gene. This enzyme mediates embryonic cellular growth in-utero and diseases involved in this pathway are classified as members of the PIK3CA-related overgrowth syndrome. This paper reviews the status of what is now known about the molecular genetics of this unusual, but clinically challenging disorder and its differentiation from similar diseases, linked with the PIK3CA-gene and the related overgrowth syndromes.

PIK3CA-related overgrowth spectrum: animal model and drug discovery

This review recapitulates the recent knowledge accumulation on overgrowth syndrome related to gain of function of the phosphoinositide3 kinase (PI3K)-alpha. These disorders, known as PIK3CA related overgrowth syndromes (PROS) are caused by somatic PIK3CA mutation occurring during embryogenesis. We summarize here the currently available animal models and new treatments undergoing development.

Non-hotspot PIK3CA mutations are more frequent in CLOVES than in common or combined lymphatic malformations

BackgroundTheragnostic management, treatment according to precise pathological molecular targets, requests to unravel patients’ genotypes. We used targeted next-generation sequencing (NGS) or digital droplet polymerase chain reaction (ddPCR) to screen for somatic PIK3CA mutations on DNA extracted from resected lesional tissue or lymphatic endothelial cells (LECs) isolated from lesions. Our cohort (n = 143) was composed of unrelated patients suffering from a common lymphatic malformation (LM), a combined lymphatic malformation [lymphatico-venous malformation (LVM), capillaro-lymphatic malformation (CLM), capillaro-lymphatico-venous malformation (CLVM)], or a syndrome [CLVM with hypertrophy (Klippel-Trenaunay-Weber syndrome, KTS), congenital lipomatous overgrowth-vascular malformations-epidermal nevi -syndrome (CLOVES), unclassified PIK3CA-related overgrowth syndrome (PROS) or unclassified vascular (lymphatic) anomaly syndrome (UVA)].ResultsWe identified a somatic PIK3CA mutation in resected lesions of 108 out of 143 patients (75.5%). The frequency of the variant allele ranged from 0.54 to 25.33% in tissues, and up to 47% in isolated endothelial cells. We detected a statistically significant difference in the distribution of mutations between patients with common and combined LM compared to the syndromes, but not with KTS. Moreover, the variant allele frequency was higher in the syndromes.ConclusionsMost patients with an common or combined lymphatic malformation with or without overgrowth harbour a somatic PIK3CA mutation. However, in about a quarter of patients, no such mutation was detected, suggesting the existence of (an)other cause(s). We detected a hotspot mutation more frequently in common and combined LMs compared to syndromic cases (CLOVES and PROS). Diagnostic genotyping should thus not be limited to PIK3CA hotspot mutations. Moreover, the higher mutant allele frequency in syndromes suggests a wider distribution in patients’ tissues, facilitating detection. Clinical trials have demonstrated efficacy of Sirolimus and Alpelisib in treating patients with an LM or PROS. Genotyping might lead to an increase in efficacy, as treatments could be more targeted, and responses could vary depending on presence and type of PIK3CA-mutation.

Clinical experience with the AKT1 inhibitor miransertib in two children with PIK3CA-related overgrowth syndrome

BackgroundPIK3CA-related overgrowth spectrum (PROS) refers to a group of rare disorders, caused by somatic activating mutations in PIK3CA, resulting in abnormal PI3K-AKT-mTOR pathway signalling. Significant associated morbidity is frequently observed, and approved treatments are lacking. Miransertib (ARQ 092) is a novel, orally available, selective pan-AKT inhibitor with proven in vitro efficacy. Following recent results of the use of AKT inhibitors in Proteus syndrome (PS) and AKT-mutant cancers, we investigated its therapeutic use in two patients with severe PROS who had exhausted conventional treatment methods.ResultsTwo patients, one with CLOVES variant (P1) and one with facial infiltrating lipomatosis and hemimegalencephaly (P2), were commenced on miransertib treatment on a compassionate use basis. In patient one, intra-abdominal and paraspinal overgrowth had resulted in respiratory compromise, obstructive uropathy, dysfunctional seating and lying postures, and chronic pain. In patient two, hemifacial overgrowth and hemimegalencephaly had caused difficulties with articulation and oral function, and refractory epilepsy. Miransertib treatment was continued for a median duration of 22 months (range 22–28). In patient one, alleviation of respiratory compromise was observed and functionally, seating and lying postures improved. Serial volumetric MRI analysis revealed 15% reduction in calculated volumes of fatty overgrowth between treatment commencement and end. In patient two, reduction in seizure burden and improved parent-reported quality of life measures were reported. Treatment was discontinued in both patients due to lack of sustained response, and poor compliance in year two of treatment (P2). No significant toxicities were reported.ConclusionWe report the first paediatric case series of the use of miransertib in two children with PROS. Objective clinical response was observed in patient one, and improvement in key qualitative outcomes was reported in patient two. Treatment was well tolerated with no significant toxicities reported. This case series highlights the potential therapeutic utility of miransertib in selected paediatric patients with severe PROS, and further demonstrates the potential for re-purposing targeted therapies for the treatment of rare diseases. An open label, Phase 1/2 study of miransertib in children with PROS and PS is underway to more accurately assess the efficacy of miransertib in the treatment of PROS disorder (NCT03094832).

The role of the PIK3CA gene in the development and aging of the brain

The CLOVES syndrome is an overgrowth disease arising from mosaic activating somatic mutations in the PIK3CA gene. These mutations occur during fetal development producing malformation and overgrowth of a variety of tissues. It has recently been shown that treatment with low doses of a selective inhibitor of Class I PI3K catalytic subunit p110α, the protein product of the PIK3CA gene, can yield dramatic therapeutic benefits for patients with CLOVES and PROS (a spectrum of PIK3CA-related overgrowth syndromes). To assess the long-term effects of moderate loses of p110α activity, we followed development and growth of mice with heterozygous loss of p110α (Pik3ca+/−) over their entire lifetimes, paying particular attention to effects on the brain. While homozygous deletion of the Pik3ca gene is known to result in early embryonic lethality, these Pik3ca+/− mice displayed a longer lifespan compared to their wild-type littermates. These mice appeared normal, exhibited no obvious behavioral abnormalities, and no body weight changes. However, their brains showed a significant reduction in size and weight. Notably, mice featuring deletion of one allele of Pik3ca only in the brain also showed gradually reduced brain size and weight. Mechanistically, either deletion of p110α or pharmacological inhibition of p110α activity reduced neurosphere size, but not numbers, in vitro, suggesting that p110α activity is critical for neuronal stem cells. The phenotypes observed in our two genetically engineered mouse models suggest that the sustained pharmacological inhibition of the PIK3CA activity in human patients might have both beneficial and harmful effects, and future treatments may need to be deployed in a way to avoid or minimize adverse effects.

Evaluation and management of the lateral marginal vein in Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes

The lateral marginal vein is an anomalous clinical entity found in association with Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes. Although it is reported to affect <20% of patients with Klippel-Trénaunay syndrome, this venous anomaly has been associated with significant morbidity and mortality attributable to venous hypertension and potentially lethal thromboembolic events. Limited literature exists on the diagnosis and management of this rare anomaly, with most of the reports focusing on retrospective clinical experience at a few centers of excellence. Despite these limitations, a systematic approach to diagnosis and treatment of this anomaly is warranted and expounded on herein. When plausible, clinical recommendations based on best available literature are made.

Clinical Profile of Overgrowth Syndromes Consistent with PROS (PIK3CA-Related Overgrowth Syndromes)-A Case Series.

Context:PIK3CA-related overgrowth syndrome (PROS) is characterized by focal and disproportionate growth of acral body structures in a mosaic pattern with varied phenotypes. Clinical diagnostic criteria are available and testing of the mutation is recommended for diagnosis. Cutaneous features described in these conditions include epidermal nevi and vascular malformations which form part of the diagnostic criteria.Aims:To detail the clinical profile of patients with presumptive PROS.Settings and Design:We conducted a retrospective study of 15 patients with focal overgrowth of the extremities or macrocephaly who presented to the department of dermatology at a tertiary care hospital in South India.Subjects and Methods:Data were collected through electronic medical records from July 2012 to April 2018 over 70 months. The criterion proposed by Keppler-Noreuil et al. was used for classifying them as presumptive PROS in the absence of genetic studies.Statistical Analysis Used:Descriptive analysis.Results:There were nine males and six females; mean age of 12.10 years (range: 8 months to 73 years) with clinical features consistent with PROS. There was a higher frequency of vascular malformations (9/15, 60%) and of epidermal nevi (7/15, 46.6%) than that reported in the literature. Unusual features included focal acrochordons, blaschkoid hypopigmentation and linear papillomatous growths in the oral mucosa.Conclusions:This study provides data on the clinical features of patients with PROS from the Indian subcontinent. In resource-poor settings, clinical criteria may be adequate for diagnosis due to restricted accessibility of technically challenging diagnostic tests.

The Novel Phosphatidylinositol-3-Kinase (PI3K) Inhibitor Alpelisib Effectively Inhibits Growth of PTEN-Haploinsufficient Lipoma Cells.

Germline mutations in the tumor suppressor gene PTEN cause PTEN Hamartoma Tumor Syndrome (PHTS). Pediatric patients with PHTS frequently develop lipomas. Treatment attempts with the mTORC1 inhibitor rapamycin were unable to reverse lipoma growth. Recently, lipomas associated with PIK3CA-related overgrowth syndrome were successfully treated with the novel PI3K inhibitor alpelisib. Here, we tested whether alpelisib has growth-restrictive effects and induces cell death in lipoma cells. We used PTEN-haploinsufficient lipoma cells from three patients and treated them with alpelisib alone or in combination with rapamycin. We tested the effect of alpelisib on viability, proliferation, cell death, induction of senescence, adipocyte differentiation, and signaling at 1–100 µM alpelisib. Alpelisib alone or in combination with rapamycin reduced proliferation in a concentration- and time-dependent manner. No cell death but an induction of senescence was detected after alpelisib incubation for 72 h. Alpelisib treatment led to a reduced phosphorylation of AKT, mTOR, and ribosomal protein S6. Rapamycin treatment alone led to increased AKT phosphorylation. This effect could be reversed by combining rapamycin with alpelisib. Alpelisib reduced the size of lipoma spheroids by attenuating adipocyte differentiation. Since alpelisib was well tolerated in first clinical trials, this drug alone or in combination with rapamycin is a potential new treatment option for PHTS-related adipose tissue overgrowth.

Megalencephaly Capillary Malformation Syndrome

AbstractMegalencephaly capillary malformation polymicrogyria (MCAP) syndrome is characterized by the sporadic occurrence of congenital and progressive megalencephaly, brain malformations including polymicrogyria, pre- and postnatal overgrowth with body asymmetry, cutaneous vascular malformations (including capillary malformation and cutis marmorata), digital anomalies connective tissue dysplasia (including skin and joint laxity), and developmental delay. In the past 10 years, the specific cause of the disease has been found in gain-of-function mutations of PIK3CA gene, mostly somatic/postzygotic but in rare cases also de novo germline. Such gene encodes for PI3K, a critical member of the PI3K-AKT-mTOR pathway: genetic changes lead to an over-activation of this signaling system, with increased vascular, limb, and brain cell development, progression, and survival. Interestingly, mutations in the same gene can cause other clinically heterogeneous syndromes, including CLOVE syndrome, macrodactyly, focal adipose overgrowth, epidermal nevi, facial infiltrating lipomatosis: all these syndromes (even if heterogeneous) are now considered a unique spectrum, known as PIK3CA-related overgrowth syndrome. On the contrary, a disease strictly similar to MCAP, characterized by megalencephaly, polymicrogyria, polydactyly, and hydrocephalus has been found to be caused by mutations in two other PI3K-AKT-mTOR-releted genes, AKT3 and PIK3R2, and for this reason is not included in the upper mentioned group of syndromes. With the exception of neurosurgery strategies for hydrocephalus and posterior fossa overcrowding, therapeutic options are nowadays limited, even if gene-targeted treatment protocols have been proposed and protocols with such agents (i.e., Arq092) are currently ongoing in small groups of patients with promising results.

Update on classification and diagnosis of vascular malformations.

This review provides an update of the classification in the classification of vascular anomalies since April 2014 at the International Society for the Study of Vascular Anomalies meeting in Melbourne, Australia. The reader will become familiar with how to diagnose the major vascular malformations, including capillary, venous, arteriovenous, and lymphatic and combinations thereof. In addition, vascular malformation syndromes, including those with overgrowth, will be clarified. Vascular malformations are common. Capillary malformations are now better understood through an updated classification. Verrucous hemangioma is truly a venulocapillary malformation that extends into the subcutis. PIK3Ca-Related Overgrowth Syndromes encompass Klippel-Trenaunay, Congenital Lipomatous Asymmetric Overgrowth of the Trunk with Lymphatic, Capillary, Venous, and Combined-Type Vascular Malformations, Epidermal Nevi, Scoliosis/Skeletal and Spinal Anomalies, Megalencephaly-Capillary Malformation-Polymicrogyria Syndrome (M-CAP), fibroadipose hyperplasia, and macrodactyly. Yet another syndrome should be highlighted: Capillary Malformation of the Lower Lip, Lymphatic Malformation of the Face and Neck, Asymmetry and Partial/Generalized Overgrowth. Knowledge of the genetic basis of vascular malformations will lead to future treatments.