Aims:
To investigate the therapeutic use of pan-AKT inhibitor miransertib (ARQ 092) in two paediatric patients with severe PIK3CA-related overgrowth spectrum disorder, both of who had exhausted conventional treatment methods.
Participant characteristics:
Patient one:
Patient one was a 16 years old female with Congenital Lipomatous Overgrowth, Vascular malformations, Epidermal nevi, Scoliosis/Skeletal/Spinal anomalies (CLOVES) phenotype (17, 18). She was born to non-consanguineous parents with a birth weight of 2.89kg (50th centile) and occipitofrontal circumference of 31.6cm (10th centile) and was noted to have a large posterior thoracic wall lipoma and large feet with splayed toes at birth. Subsequent musculoskeletal examination identified a dislocated right hip and bilateral talipes equinovarus. Progressive intra-abdominal and paraspinal lipomatous overgrowth created significant difficulties with mobility and seating; these were treated with debulking procedures and liposuction during the first 10 years of life. While these procedures lead to partial but temporary improvement, the lipomatous lesions regrew within 12 months. Despite repeated orthopaedic intervention, she developed progressive lower limb discrepancy and subsequent flexed deformity of the right lower limb, resulting in loss of function.
At the age of four, she presented with a urinary tract infection and was found to have marked bladder wall thickening and irregularity on ultrasound suggestive of neuropathic bladder, along with bilateral hydronephrosis. Functional studies demonstrated focal scarring of the right kidney. Urodynamics confirmed a large, atonic bladder with incomplete voiding. Chronic renal failure, with estimated function 50% of normal range first became evident aged seven. Due to anterior displacement of the bladder by progressive infiltrative lipomatous overgrowth, an obstructive uropathy component also developed, requiring placement of a suprapubic catheter.
By the age of thirteen, she was completely wheelchair bound and had frequent hospital admissions for recurrent urinary tract infections. Chronic pain became a severely disabling problem, and her progressive intra-abdominal overgrowth resulted in difficulties with lying and seating. She was treated with mTOR inhibitor sirolimus aged fifteen for a period of 12 months. Sub-therapeutic troughs were observed despite incremental dosing increases, and treatment was stopped after one year due to progression of her disease.
Progressive respiratory compromise from diaphragm elevation caused by intra-abdominal lipomatous overgrowth, and relentless flank pain from massive lipomatous distension determined the urgency of further treatment. Surgical therapeutic approaches were not favoured due to the infiltrative nature of fatty overgrowth encasing vital structures in the retroperitoneum, thus necessitating investigation of novel medical therapeutic approaches.
PATIENT TWO:
Patient two was a five years old male with PROS-associated facial infiltrating lipomatosis and hemimegalencephaly phenotype. He was born to non-consanguineous parents at term by elective Caesarian section for unstable lie with a birth weight of 4.15kg (75th centile) and occipitofrontal circumference of 40.3cm (>99.6th centile). On examination he was noted to have right hemifacial macrosomia but no other signs of hemi-hypertrophy. His neonatal course was complicated by focal onset seizures day seven of life, characterised by right occipital discharges on electroencephalogram. Magnetic resonance imaging of the brain at three months reported right hemimegalencephaly and polymicrogyria of the parietal lobe with cortical thickening and malformation, particularly in the occipital lobe (Figure 1).
During the first few years of life, profound hemifacial and soft tissue and skeletal overgrowth began to affect the oral commissure on the right side, and hemi-macroglossia and macrodontia caused progressive difficulties with articulation and oral function. Magnetic resonance imaging (MRI) showed extensive fatty hypertrophy and infiltration of the right side of the face, including the tongue and facial musculature (Figure 2). Repeated liposuction and excision of excess tissue was undertaken for debulking and symmetrisation with a therapeutic aim of improving function. However progressive bony overgrowth was also evident which was deemed impossible to correct until skeletal maturation was reached. Executive functioning difficulties became apparent, consistent with right hemisphere abnormalities, reflected by attention and behavioural dysregulation difficulties. Additional educational support was also required due to low average scores obtained in general verbal and non-verbal skills on neuropsychological assessments.
He was commenced on sirolimus aged five for a period of eight months and achieved therapeutic levels of 5–10ng/ml, but ongoing progression of his disease resulted in early discontinuation of treatment. Increased seizure frequency and an emerging subtle left-sided motor deficit in addition to relentless hemifacial overgrowth despite multiple surgical interventions rendered further consideration of targeted medical treatment important.
Molecular investigations:
Molecular investigations were undertaken in both patients to help guide therapeutic approaches. In patient one, cellular studies demonstrated high levels of AKT activation in fibroblasts from the affected area. Subsequent genetic analysis of affected tissue identified a mutation in PIK3CA (c.3140A>G p.His1047Arg) with reported variant frequency 12%. In patient two, genetic testing of affected fibroblasts demonstrated a C42OR mutation on exon 7 of PIK3CA, with variant frequency 15%, confirming PIK3CA-related overgrowth spectrum disorder. The mutations were revealed by targeted next generation sequencing (NGS) technology of genes involved in the P13K/AKT pathway and confirmed by Sanger sequencing methodologies. Next generation sequencing was carried out on Ion Torrent Personal Genome Machine (ThermoFisher Scientific, TFS), using the Ion PGM Sequencing Hi-Q 200 Kit (TFS) according to the manufacturer’s instructions (Loconte et al.,, 2015). Data analysis was performed using the Torrent Suite Software v5.0.5 (TFS). Reads were aligned to the hg19 human reference genome from the UCSC Genome Browser (http://genome.ucsc.edu/) and to the BED file designed using Ion AmpliSeq Designer. Alignments were visually verified with the software Alamut® v2.8.0 (Interactive Bio software). Coverage and variant analysis were conducted according to methods previously reported by Loconte et al (19).
Investigational treatment with miransertib (ARQ 092):
Due to the severe, progressive nature of overgrowth in both cases resulting in increasing morbidity, and the lack of alternative available approved treatments, the use of novel experimental therapies was investigated. Applications for the compassionate use of the experimental drug, miransertib, were submitted to and approved by the Drugs and Therapeutics committee of Children’s Health Ireland, Crumlin (Dublin, Ireland); the Health Product Regulatory Agency of Ireland (HPRA) was informed of the orphan use of this drug and their adverse event reporting system was adhered to during the period of therapy. Initial dosing of 5mg/m2/day was determined based on tolerability and efficacy reports in a phase 1 clinical trial investigating the use of miransertib in adult and paediatric patients over 12 years with PS (14). ArQule Inc. (Burlington MA) provided miransertib on a managed patient access programme basis for both patients.
Informed consent was obtained from the legal guardians of both patients prior to treatment commencement. Baseline pre-treatment assessments were carried out, including evaluation of complete blood count, renal, liver, bone and fasting lipid profile and urinalysis. Transthoracic echo was undertaken to assess cardiac function. Volumetric MRI analysis of the targeted overgrowth area was also performed pre-treatment and every three months thereafter.
Subsequent monitoring included weekly assessment for glycosuria and point of care testing for hyperglycaemia. Evaluations of complete blood count, renal, liver and bone profile were repeated at week 4 and week 8 and every 8 weeks thereafter for the treatment duration. Adverse effects were classified according to the Common Terminology Criteria forAdverse Events, version 5.0 (CTCAE v.5.0) (19). Where possible, serial volumetric analysis of DIXON MRI was carried out by a radiologist blinded to the patient’s medical history and visit schedule using Dynamika software (Image Analysis Group) as a platform for imaging data analysis.