In vitro efficacy of ARQ 092, an allosteric AKT inhibitor, on primary fibroblast cells derived from patients with PIK3CA-related overgrowth spectrum (PROS)

Abstract

Postzygotic mutations of the PIK3CA [phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha] gene constitutively activate the PI3K/AKT/mTOR pathway in PIK3CA-related overgrowth spectrum (PROS) patients, causing congenital mosaic tissue overgrowth that even multiple surgeries cannot solve. mTOR inhibitors are empirically tested and given for compassionate use in these patients. PROS patients could be ideal candidates for enrolment in trials with PI3K/AKT pathway inhibitors, considering the “clean” cellular setting in which a unique driver, a PIK3CA mutation, is present. We aimed to assess the effects of blocking the upstream pathway of mTOR on PROS patient-derived cells by using ARQ 092, a potent, selective, allosteric, and experimental orally bioavailable and highly selective AKT-inhibitor with activity and long-term tolerability, currently under clinical development for treatment of cancer and Proteus syndrome. Cell samples (i.e., primary fibroblasts) were derived from cultured tissues obtained from six PROS patients [3 boys, 3 girls; aged 2 to 17 years] whose spectrum of PIK3A-related overgrowth included HHML [hemihyperplasia multiple lipomatosis; n = 1], CLOVES [congenital lipomatosis, overgrowth, vascular malformations, epidermal nevi, spinal/skeletal anomalies, scoliosis; n = 1], and MCAP [megalencephaly capillary malformation syndrome; n = 4]. We performed the following: (a) a deep sequencing assay of PI3K/AKT pathway genes in the six PROS patients’ derived cells to identify the causative mutations and (b) a pathway analysis to assess the phosphorylation status of AKT [Ser473 and Thr308] and its downstream targets [pAKTS1 (Thr246), pRPS6 (Ser235/236), and pRPS6Kβ1 (Ser371)]. The anti-proliferative effect of ARQ 092 was tested and compared to other PI3K/AKT/mTOR inhibitors [i.e., wortmannin, LY249002, and rapamycin] in the six PROS patient-derived cells. Using ARQ 092 to target AKT, a critical node connecting PI3K and mTOR pathways, we observed the following: (1) strong anti-proliferative activity [ARQ 092 at 0.5, 1, and 2.5 μM blunted phosphorylation of AKT and its downstream targets (in the presence or absence of serum) and inhibited proliferation after 72 h; rapamycin at 100 nM did not decrease AKT phosphorylation] and (2) less cytotoxicity as compared to rapamycin and wortmannin. We demonstrated the following: (a) that PROS cells are dependent on AKT; (b) the advantage of inhibiting the pathway immediately downstream of PI3K to circumventing problems depending on multiple classes a PI3K kinases; and (c) that PROS patients benefit from inhibition of AKT rather than mTOR. Clinical development of ARQ 092 in PROS patients is on going in these patients.Electronic supplementary materialThe online version of this article (10.1007/s10048-018-0540-1) contains supplementary material, which is available to authorized users.

Constitutive activation of the PI3K‐AKT pathway and cardiovascular abnormalities in an individual with Kosaki overgrowth syndrome

“…This documented overactive PI3K‐AKT pathway opens the option to potential additional therapeutic alternatives targeting this pathway for individuals with KOGS in addition to PDGFRB inhibitors (Pond et al, ). Treatments aimed at blocking downstream AKT signaling have been documented to inhibit this pathway in a dose‐ and time‐dependent manner in cells derived from individuals with activating mutations of PIK3CA and currently undergoing clinical trials in patients with PIK3CA‐related overgrowth spectrum (Ranieri et al, ).…”

Signaling pathways and inhibitors of cells from patients with kaposiform lymphangiomatosis

“…ARQ092 (miransertib) is a new allosteric inhibitor of AKT that is orally bioavailable and has a manageable safety profile in patients with advanced solid tumors. Studies using fibroblasts from PROS patients showed that ARQ092 had good antiproliferative activity and has now been granted “Fast Track” designation by the Food and Drug Administration for the treatment of PROS as well as Rare Pediatric Disease designation for the treatment of Proteus syndrome…”

“…21 The mTOR inhibitor sirolimus (rapamycin) has been used to treat KLA patients with a partial response in KLA patients. 2 24 and has now been granted "Fast Track" designation by the Food and Drug Administration for the treatment of PROS as well as Rare Pediatric Disease designation for the treatment of Proteus syndrome. 25 Based on this promising background, we thought that it might be beneficial to evaluate this new drug in cells from KLA patients to generate data of preclinical interest since these cells have hyperactive AKT.…”

Comprehensive molecular and clinicopathological analysis of vascular malformations: A study of 319 cases

“…Furthermore, it can provide clues for an underlying hereditary condition due to a germline mutation. In addition, increased knowledge of pathogenic mutations present in these lesions can stratify patients for targeted therapeutic options . A comprehensive and sensitive analysis is required because of the spectrum of genes involved and the mosaicism with low levels of mutated cells and also combined mutations.…”