Pathogenetic insights from quantification of the cerebriform connective tissue nevus in Proteus syndrome

Quantification of Proteus syndrome-associated lung disease

BACKGROUND

Proteus syndrome is an ultra-rare mosaic overgrowth disorder. Individuals with Proteus syndrome can develop emphysematous and cystic changes of the lung that may lead to progressive respiratory symptoms and require surgical intervention. This retrospective study seeks to quantify the radiographic features of Proteus syndrome-associated lung disease using computed tomography (CT) of the chest. The first method derives a Cystic Lung Score (CLS) by using a computer-aided diagnostic tool to quantify the fraction of cystic involvement of the lung. The second method yields a Clinician Visual Score (CVS), an observer reported scale of severity based on multiple radiographic features. The aim of this study was to determine if these measurements are associated with clinical symptoms, pulmonary function test (PFT) measurements, and if they may be used to assess progression of pulmonary disease.

RESULTS

One hundred and thirteen imaging studies from 44 individuals with Proteus syndrome were included. Dyspnea and oxygen use were each associated with higher CLS (p = 0.001 and < 0.001, respectively) and higher CVS (p < 0.001 and < 0.001). Decreases in percent predicted FVC, FEV1, and DLCO each correlated with increased CLS and CVS. The annual increase of CLS in children, 5.6, was significantly greater than in adults, 1.6. (p = 0.03). The annual increase in CVS in children, 0.4, was similar to adults, 0.2 (p = 0.36).

CONCLUSIONS

Proteus syndrome-associated lung disease is progressive. The rate of cystic progression is increased in children. Increased scores in CLS and CVS were associated with clinical symptoms and decreased pulmonary function. Both methods were able to detect change over time and were associated with clinically meaningful outcomes which may enable their use in interventional studies.

Epidermal nevus superimposed by psoriatic plaque in a girl with proteous syndrome

Proteus syndrome (PS) is a rare syndrome characterized by asymmetric limb overgrowth, vascular malformation, and hamartomas. In this study we report a case of PS in a 13-year-old girl with chief complaint of a new cutaneous lesion that was diagnosed and treated as leishmaniasis.

Late-onset Proteus syndrome with cerebriform connective tissue nevus and subsequent development of intraductal papilloma

Proteus syndrome (PS) is a rare segmental overgrowth disorder caused by a mosaic activating variant in AKT1. The features of PS are often not present at birth but develop during the first few years of life. We describe a 55-year-old female, whose first symptom of overgrowth, a cerebriform connective tissue nevus, occurred at 19 years of age. We report the identification of the AKT1 c.49G > A p.(Glu17Lys) variant in this progressive lesion, the bony overgrowth, and recurrence after surgical intervention. In the sixth decade of life, this individual developed intraductal papillomas within her right breast which were confirmed to contain the same activating AKT1 variant as the connective tissue nevus. While similar neoplasms have been described in an individual with Proteus syndrome, none has been evaluated for the presence of the AKT1 variant. The tumor also contained two likely pathogenic variants in PIK3R1, c.1392_1403dupTAGATTATATGA p.(Asp464_Tyr467dup) and c.1728_1730delGAG p.(Arg577del). The finding of additional genetic variation putatively affecting the PI3K/AKT pathway in the neoplastic tissue may provide preliminary evidence of a molecular mechanism for tumorigenesis in PS. The late onset of symptoms and molecular characterization of the breast tumor expand the clinical spectrum of this rare disorder.

Development of the Clinical Gestalt Assessment: a visual clinical global impression scale for Proteus syndrome

BACKGROUND

Clinical outcome assessments are important tools for measuring the natural history of disease and efficacy of an intervention. The heterogenous phenotype and difficult to quantity features of Proteus syndrome present challenges to measuring clinical outcomes. To address these, we designed a global clinical assessment for Proteus syndrome, a rare mosaic overgrowth disorder. The Clinical Gestalt Assessment (CGA) aims to evaluate change over time in this phenotypically diverse disorder.

RESULTS

We gathered paired serial photographs and radiographs obtained at 12-to-36-month intervals from our natural history study of Proteus syndrome. The chronologic order of each set was blinded and presented to clinicians familiar with overgrowth disorders. They were asked to determine the chronologic order and, based on that response, rate global clinical change using a seven-point scale (Much Worse, Worse, Minimally Worse, No Change, Minimally Improved, Improved, Much Improved). Following a pilot, we tested the inter-rater reliability of the CGA using eight cases rated by eight clinicians. Raters identified the correct chronologic order in 53 of 64 (83%) of responses. There was low inter-rater variance and poor to moderate reliability with an intraclass correlation coefficient of 0.46 (95% CI 0.24-0.75). The overall estimate of global change was Minimally Worse over time, which is an accurate reflection of the natural history of Proteus syndrome.

CONCLUSIONS

The CGA is a tool to evaluate clinical change over time in Proteus syndrome and may be a useful adjunct to measure clinical outcomes in prospective therapeutic trials.

Case report: five-year experience of AKT inhibition with miransertib (MK-7075) in an individual with Proteus syndrome

Proteus syndrome is a rare overgrowth disorder caused by postzygotic activating variants in AKT1. Individuals may develop a range of skin, bone, and soft tissue overgrowth leading to functional impairment and disfigurement. Therapy for this disorder is limited to supportive care and surgical intervention. Inhibitors of AKT, originally designed as cancer therapeutics, are a rational, targeted pharmacologic strategy to mitigate the devastating morbidity of Proteus syndrome. We present the 5-yr follow-up of an 18-yr-old male with Proteus syndrome treated with miransertib (MK-7075), an oral pan-AKT inhibitor. At completion of a planned 48-wk phase 1 pharmacodynamic study, the individual derived sufficient benefit that the study was amended to permit continued use and assess the long-term safety of miransertib. The treatment has been well-tolerated with mild treatment-attributed side effects including headache, transient hyperglycemia, and transient elevations of aspartate aminotransferase, alanine aminotransferase, and bilirubin. The patient has experienced sustained improvement of pain and slowed growth of bilateral plantar cerebriform connective tissue nevi. This case report supplements the data from our prior study extending those findings out to 5 years. It shows that at the doses used, miransertib has a favorable safety profile and durable benefit of improving symptoms of pain and slowing progression of overgrowth in Proteus syndrome in a single individual. Although an uncontrolled single report cannot prove safety or efficacy, these data lend support to the encouraging preliminary data of our prior phase 1 pharmacodynamic study.

Dermatologic findings in individuals with genetically confirmed Proteus syndrome

BACKGROUND/OBJECTIVE

Proteus syndrome, caused by a mosaic activating AKT1 variant, typically presents in toddlers with progressive, asymmetric overgrowth of the skin and bones. We aimed to define the spectrum of dermatologic disease in individuals with genetically confirmed Proteus syndrome.

METHODS

We conducted a retrospective review of records from dermatologic examinations of individuals evaluated at the NIH with a molecular diagnosis of Proteus syndrome. The types, prevalence, and localization of dermatologic findings were assessed.

RESULTS

Fifty-one individuals (29 males, 22 females, mean age: 9 years) with clinical features of Proteus syndrome had the mosaic c.49G>A, p.Glu17Lys AKT1 variant. Fifty (98%) had at least one cutaneous feature constituting current clinical diagnostic criteria, including vascular malformations in 42 (82%), epidermal nevus in 41 (80%), volar cerebriform connective tissue nevi in 34 (67%), and adipose dysregulation in 30 (59%). Forty-nine (96%) had at least one dermatologic finding not included within the diagnostic criteria, including confluent volar skin-colored to hypopigmented papules or nodules (n = 33, 65%), papules or nodules on the digits or face (n = 27, 53%), and nonlinear epidermal nevi (n = 15, 29%). Other frequently observed features include nail changes (n = 28, 55%), hyperpigmented macules (n = 27, 53%), patchy dermal hypoplasia (n = 18, 35%), gingival/oral mucosal overgrowth (n = 17, 33%), hypopigmented macules (n = 16, 31%), dental enamel changes (n = 9, 18%), acrochordons (n = 6, 12%), and lingual overgrowth (n = 4, 8%).

CONCLUSIONS

The range of mucocutaneous features occurring in Proteus syndrome is broader than previously considered. These observations may assist in earlier diagnosis and management and provide novel insights regarding the pathogenesis of the condition.

A mouse model of Proteus syndrome

Proteus syndrome is a mosaic, progressive overgrowth disorder caused by a somatic activating variant c.49G > A p.(E17K) in AKT1. The presentation in affected individuals is variable, with a diversity of tissues demonstrating abnormalities. Common manifestations include skin and bony overgrowth, vascular malformations (VMs), cysts and benign tumors. We used two methods to create mouse models that had endogenously-regulated mosaic expression of the Proteus syndrome variant. Variant allele fractions (VAFs) ranged from 0% to 50% across numerous tissues in 44 Proteus syndrome mice. Mice were phenotypically heterogeneous with lesions rarely observed before 12 months of age. VMs were the most frequent finding with a total of 69 found in 29 of 44 Proteus syndrome mice. Twenty-eight cysts and ectasia, frequently biliary, were seen in 22 of 44 Proteus syndrome mice. Varying levels of mammary hyperplasia were seen in 10 of 16 female Proteus syndrome mice with other localized regions of hyperplasia and stromal expansion noted in several additional animals. Interestingly, 27 of 31 Proteus syndrome animals had non-zero blood VAF that is in contrast to the human disorder where it is rarely seen in peripheral blood. Identification of variant-positive cells by green fluorescent protein (GFP) staining in chimeric Proteus syndrome mice showed that in some lesions, hyperplastic cells were predominantly GFP/Akt1E17K-positive and showed increased pAKT signal compared to GFP-negative cells. However, hyperplastic mammary epithelium was a mixture of GFP/Akt1E17K-positive and negative cells with some GFP/Akt1E17K-negative cells also having increased pAKT signal suggesting that the variant-positive cells can induce lesion formation in a non-cell autonomous manner.

A case report of Proteus syndrome (PS)

BACKGROUND

Proteus syndrome (PS) is an extremely rare disease characterized by excessive chimeric growth of cells, and progressive and irregular asymmetrical hyperplasia.

CASE PRESENTATION

Herein, a PS case with atypical clinical features and syndromes was reported, to improve the understanding of the diagnosis and treatment of the disease. The case was a 3-year-and-11-month-old male child. He was admitted due to a primary diagnosis of McCune-Albright syndrome. After admission, the lesion samples from the milk coffee spots, and nodular thickening skin at hands and feet were subjected to genetic screening. Genetic testing results confirmed the diagnosis of PS.

CONCLUSIONS

Based on the clinical manifestations, laboratory tests, imaging data, and literature reviewing, the etiology, diagnosis, treatment and prognosis of PS have been analyzed and discussed.

Vascular malformations syndromes: an update

PURPOSE OF REVIEW

To provide an update of vascular malformation syndromes by reviewing the most recent articles on the topic and following the new International Society for the Study of Vascular Anomalies (ISSVA) 2018 classification.

RECENT FINDINGS

This review discusses the main features and diagnostic approaches of the vascular malformation syndromes, the new genetic findings and the new therapeutic strategies developed in recent months.

SUMMARY

Some vascular malformations can be associated with other anomalies, such as tissue overgrowth. PIK3CA-related overgrowth spectrum (PROS) is a group of rare genetic disorders with asymmetric overgrowth caused by somatic mosaic mutations in PI3K-AKT-mTOR pathway that encompass a heterogeneous group of rare disorder that are associated with the appearance of overgrowth. CLOVES syndrome and Klippel-Trénaunay syndrome are PROS disease. Proteus syndrome is an overgrowth syndrome caused by a somatic activating mutation in AKT1. CLOVES, Klippel-Trénaunay and Proteus syndromes are associated with high risk of thrombosis and pulmonary embolism. Hereditary hemorrhagic telangiectasia is an autosomic dominant disorder characterized by the presence of arteriovenous malformations. New therapeutic strategies with bevacizumab and thalidomide have been employed with promising results.

Molecular heterogeneity of the cerebriform connective tissue nevus in mosaic overgrowth syndromes

The clinical diagnostic criteria for Proteus syndrome were defined before the discovery of the AKT1 c.49G>A; p.(Glu17Lys) causal variant and used a combination of general and specific phenotypic attributes that could be combined to make a clinical diagnosis. The most heavily weighted specific criterion was the cerebriform connective tissue nevus (CCTN). Here, we describe two individuals with connective tissue nevi (CTNs) and some general attributes of Proteus syndrome who were found to have mosaic PIK3CA variants. CTNs on the soles of individuals with PIK3CA-related overgrowth typically exhibit thickening of the soft tissues with at most a wrinkled surface, but these two patients had firm plaques with ridges and furrows characteristic of CCTNs, which was histologically confirmed in one. These data show that CCTNs are not specific to Proteus syndrome and that clinicians should be cautious in diagnosing individuals with Proteus syndrome based on the CCTN alone. Rather, a complete evaluation should include careful assessment of other attributes of the diagnostic criteria and, whenever possible, genetic analysis of affected tissue.

First evidence of a therapeutic effect of miransertib in a teenager with Proteus syndrome and ovarian carcinoma

Proteus syndrome (PS) is an ultra-rare disease characterized by progressive, disproportionate, segmental overgrowth caused by a somatic gain-of-function mutation p.Glu17Lys in the oncogene AKT1. The disease has high morbidity and mortality rates due to the increased risk for patients to develop cancer and progressive overgrowth. A teenage patient with severe PS phenotype developed a pelvic recurrence of low-grade serous ovarian carcinoma (LGSOC). Taking into consideration, recent results of the use of AKT inhibitors both in PS and AKT-mutant cancers, we treated the patient on a compassionate basis, with miransertib (ARQ 092), a potent, selective, allosteric AKT inhibitor. Targeted deep sequencing assay of PI3K/AKT pathway genes of the affected overgrowth lesion (cerebriform connective tissue nevus) and the tumor tissues detected the same activating AKT1 mutation in both. Treatment with miransertib led to a complete remission of the cancer and a significant improvement in the patients' everyday life. The treatment is still ongoing at 22 months. This is the first report showing the therapeutic effects of an AKT inhibitor on both benign and malignant tissues that harbor the same pathogenic AKT1 mutation. The present article showed that personalized medicine is feasible in ultra-rare diseases.

Pharmacodynamic Study of Miransertib in Individuals with Proteus Syndrome

Proteus syndrome is a life-threatening segmental overgrowth syndrome caused by a mosaic gain-of-function AKT1 variant. There are no effective treatments for Proteus syndrome. Miransertib is an AKT1 inhibitor that, prior to this study, has been evaluated only in adult oncology trials. We designed a non-randomized, phase 0/1 pilot study of miransertib in adults and children with Proteus syndrome to identify an appropriate dosage starting point for a future efficacy trial using a pharmacodynamic endpoint. The primary endpoint was a 50% reduction in the tissue levels of AKT phosphorylation from biopsies in affected individuals. We also evaluated secondary efficacy endpoints. We found that a dose of 5 mg/m²/day (1/7 the typical dose used in oncology) led to a 50% reduction in phosphorylated AKT (pAKT) in affected tissues from five of six individuals. This dose was well tolerated. Two of the six efficacy endpoints (secondary objectives) suggested that this agent may be efficacious. We observed a decrease in a cerebriform connective tissue nevus and a reduction in pain in children. We conclude that 5 mg/m²/day of miransertib is an appropriate starting point for future efficacy trials and that this agent shows promise of therapeutic efficacy in children with Proteus syndrome.