Metabolic Fingerprinting Links Oncogenic PIK3CA with Enhanced Arachidonic Acid-Derived Eicosanoids.

Oncogenic transformation is associated with profound changes in cellular metabolism, but whether tracking these can improve disease stratification or influence therapy decision-making is largely unknown. Using the iKnife to sample the aerosol of cauterized specimens, we demonstrate a new mode of real-time diagnosis, coupling metabolic phenotype to mutant PIK3CA genotype. Oncogenic PIK3CA results in an increase in arachidonic acid and a concomitant overproduction of eicosanoids, acting to promote cell proliferation beyond a cell-autonomous manner. Mechanistically, mutant PIK3CA drives a multimodal signaling network involving mTORC2-PKCζ-mediated activation of the calcium-dependent phospholipase A2 (cPLA2). Notably, inhibiting cPLA2 synergizes with fatty acid-free diet to restore immunogenicity and selectively reduce mutant PIK3CA-induced tumorigenicity. Besides highlighting the potential for metabolic phenotyping in stratified medicine, this study reveals an important role for activated PI3K signaling in regulating arachidonic acid metabolism, uncovering a targetable metabolic vulnerability that largely depends on dietary fat restriction. VIDEO ABSTRACT.

Structural Basis for Regulation of Phosphoinositide Kinases and Their Involvement in Human Disease.

Lipid phosphoinositides play fundamental roles in virtually all pathways that control a cell's decision to grow, move, divide, and die. Because of this, kinases that phosphorylate phosphoinositide lipids are critically involved in myriad essential functions including growth, development, and membrane trafficking. The misregulation of phosphoinositide kinases is critical in human diseases, including cancer, primary immunodeficiencies, and developmental disorders. Phosphoinositide kinases also play a role in mediating bacterial and viral infections for many potent human pathogens. Furthermore, inhibitors of parasite phosphoinositide kinases are in development as therapies for both malaria and cryptosporidiosis. Therefore, understanding how phosphoinositide kinases are regulated has implications for the treatment of many devastating human diseases. Recent structures of phosphoinositide kinases have revealed unique molecular insight into their regulation. This review will summarize our current molecular knowledge on phosphoinositide kinase regulation, and how this information is being used to generate novel small molecule inhibitors as potential therapeutics.

Protein interaction network analysis of mTOR signaling reveals modular organization.

The mammalian target of rapamycin (mTOR) is a serine-threonine kinase that acts as a central mediator of translation and plays important roles in cell growth, synaptic plasticity, cancer, and a wide range of developmental disorders. The signaling cascade linking lipid kinases (phosphoinositide 3-kinases), protein kinases (AKT), and translation initiation complexes (EIFs) to mTOR has been extensively modeled, but does not fully describe mTOR system behavior. Here, we use quantitative multiplex coimmunoprecipitation to monitor a protein interaction network (PIN) composed of 300+ binary interactions among mTOR-related proteins. Using a simple model system of serum-deprived or fresh-media-fed mouse 3T3 fibroblasts, we observed extensive PIN remodeling involving 27+ individual protein interactions after 1 h, despite phosphorylation changes observed after only 5 min. Using small molecule inhibitors of phosphoinositide 3-kinase, AKT, mTOR, MEK and ERK, we define subsets of the PIN, termed "modules", that respond differently to each inhibitor. Using primary fibroblasts from individuals with overgrowth disorders caused by pathogenic PIK3CA or MTOR variants, we find that hyperactivation of mTOR pathway components is reflected in a hyperactive PIN. Our data define a "modular" organization of the mTOR PIN in which coordinated groups of interactions respond to the activation or inhibition of distinct nodes, and demonstrate that kinase inhibitors affect the modular network architecture in a complex manner, inconsistent with simple linear models of signal transduction.

Genomic dissection and mutation-specific target discovery for breast cancer PIK3CA hotspot mutations.

BACKGROUND: Recent advancements in high-throughput genomics and targeted therapies have provided tremendous potential to identify and therapeutically target distinct mutations associated with cancers. However, to date the majority of targeted therapies are used to treat all functional mutations within the same gene, regardless of affected codon or phenotype. RESULTS: In this study, we developed a functional genomic analysis workflow with a unique isogenic cell line panel bearing two distinct hotspot PIK3CA mutations, E545K and H1047R, to accurately identify targetable differences between mutations within the same gene. We performed RNA-seq and ATAC-seq and identified distinct transcriptomic and epigenomic differences associated with each PIK3CA hotspot mutation. We used this data to curate a select CRISPR knock out screen to identify mutation-specific gene pathway vulnerabilities. These data revealed AREG as a E545K-preferential target that was further validated through in vitro analysis and publicly available patient databases. CONCLUSIONS: Using our multi-modal genomics framework, we discover distinct differences in genomic regulation between PIK3CA hotspot mutations, suggesting the PIK3CA mutations have different regulatory effects on the function and downstream signaling of the PI3K complex. Our results demonstrate the potential to rapidly uncover mutation specific molecular targets, specifically AREG and a proximal gene regulatory region, that may provide clinically relevant therapeutic targets. The methods outlined provide investigators with an integrative strategy to identify mutation-specific targets for the treatment of other oncogenic mutations in an isogenic system.

Clinical and Genetic Characteristics of Early and Advanced Gastric Cancer.

Gastric cancer (GC) persists as the fourth most prevalent cause of global cancer-related mortality, presenting a challenge due to the scarcity of available therapeutic strategies. Precision medicine is crucial not only in the treatment but also in the management of GC. We performed gene panel sequencing with Oncomine focus assay comprising 52 cancer-associated genes and MSI analysis in 100 case-matched gastric cancer cases. A comprehensive analysis of clinical and genetic characteristics was conducted on these genetic results and clinicopathological findings. Upon comparison of clinicopathological characteristics, significant differences between early gastric cancer (EGC) and advanced gastric cancer (AGC) were observed in tumor location (p = 0.003), Lauren classification (p = 0.015), T stage (p = 0.000), and N stage (p = 0.015). The six most frequently mutated genes were PIK3CA (29%, 10/35), ERBB2 (17%, 6/35), KRAS (14%, 5/35), ALK (6%, 2/35), ESR1 (6%, 2/35), and FGFR3 (6%, 2/35). Regarding genetic variation, there was a tendency for the N stage to be higher in GC patients with mutated genes (p = 0.014). The frequency of mutations in GC patients was statistically significantly higher in AGC (n = 24) compared to EGC (n = 11) (odds ratio, 2.792; 95% confidence interval, 1.113 to 7.007; p = 0.026). Six of the ten GC patients carrying mutated genes and exhibiting MSI were classified into intestinal-type and undifferentiated GC, with the location of the tumor being in the lower-third. Among these patients, five harbored mutated PIK3CA, while the remaining patient had a mutation in ALK. Conclusions: AGC patients more frequently exhibited alterations of PIK3CA, KRAS, and ERBB2 as somatic oncogenic drivers, and displayed a higher prevalence of cumulative genetic events, including increased rates of PIK3CA mutations, enhanced detection of immunotherapy biomarkers, and mutations of the ESR1 gene.

Somatic MAP3K3 mutation defines a subclass of cerebral cavernous malformation.

Cerebral cavernous malformations (CCMs) are vascular disorders that affect up to 0.5% of the total population. About 20% of CCMs are inherited because of familial mutations in CCM genes, including CCM1/KRIT1, CCM2/MGC4607, and CCM3/PDCD10, whereas the etiology of a majority of simplex CCM-affected individuals remains unclear. Here, we report somatic mutations of MAP3K3, PIK3CA, MAP2K7, and CCM genes in CCM lesions. In particular, somatic hotspot mutations of PIK3CA are found in 11 of 38 individuals with CCMs, and a MAP3K3 somatic mutation (c.1323C>G [p.Ile441Met]) is detected in 37.0% (34 of 92) of the simplex CCM-affected individuals. Strikingly, the MAP3K3 c.1323C>G mutation presents in 95.7% (22 of 23) of the popcorn-like lesions but only 2.5% (1 of 40) of the subacute-bleeding or multifocal lesions that are predominantly attributed to mutations in the CCM1/2/3 signaling complex. Leveraging mini-bulk sequencing, we demonstrate the enrichment of MAP3K3 c.1323C>G mutation in CCM endothelium. Mechanistically, beyond the activation of CCM1/2/3-inhibited ERK5 signaling, MEKK3 p.Ile441Met (MAP3K3 encodes MEKK3) also activates ERK1/2, JNK, and p38 pathways because of mutation-induced MEKK3 kinase activity enhancement. Collectively, we identified several somatic activating mutations in CCM endothelium, and the MAP3K3 c.1323C>G mutation defines a primary CCM subtype with distinct characteristics in signaling activation and magnetic resonance imaging appearance.

Identification of an HLA-A*11:01-restricted neoepitope of mutant PIK3CA and its specific T cell receptors for cancer immunotherapy targeting hotspot driver mutations.

Hotspot driver mutations presented by human leukocyte antigens might be recognized by anti-tumor T cells. Based on their advantages of tumor-specificity and immunogenicity, neoantigens derived from hotspot mutations, such as PIK3CAH1047L, may serve as emerging targets for cancer immunotherapies. NetMHCpan V4.1 was utilized for predicting neoepitopes of PIK3CA hotspot mutation. Using in vitro stimulation, antigen-specific T cells targeting the HLA-A*11:01-restricted PIK3CA mutation were isolated from healthy donor-derived peripheral blood mononuclear cells. T cell receptors (TCRs) were cloned using single-cell PCR and sequencing. Their functionality was assessed through T cell activation markers, cytokine production and cytotoxic response to cancer cell lines pulsed with peptides or transduced genes of mutant PIK3CA. Immunogenic mutant antigens from PIK3CA and their corresponding CD8+ T cells were identified. These PIK3CA mutation-specific CD8+ T cells were subsequently enriched, and their TCRs were isolated. The TCR clones exhibited mutation-specific and HLA-restricted reactivity, demonstrating varying degrees of functional avidity. Identified TCR genes were transferred into CD8+ Jurkat cells and primary T cells deficient of endogenous TCRs. TCR-expressing cells demonstrated specific recognition and reactivity against the PIK3CAH1047L peptide presented by HLA-A*11:01-expressing K562 cells. Furthermore, mutation-specific TCR-T cells demonstrated an elevation in cytokine production and profound cytotoxic effects against HLA-A*11:01+ malignant cell lines harboring PIK3CAH1047L. Our data demonstrate the immunogenicity of an HLA-A*11:01-restricted PIK3CA hotspot mutation and its targeting therapeutic potential, together with promising candidates of TCR-T cell therapy.

Sodium-glucose cotransporter-2 inhibitors for hypergycemia in phosphoinositide 3-kinase pathway inhibition.

PURPOSE: Phosphoinositide 3-kinase (PI3K) inhibition is used for the treatment of certain cancers, but can cause profound hyperglycemia and insulin resistance, for which sodium-glucose cotransporter-2 (SGLT2) inhibitors have been proposed as a preferred therapy. The objective of this research is to assess the effectiveness and safety of SGLT2 inhibitors for hyperglycemia in PI3K inhibition. METHODS: We conducted a single-center retrospective review of adults initiating the PI3K inhibitor alpelisib. Exposure to different antidiabetic drugs and adverse events including diabetic ketoacidosis (DKA) were assessed through chart review. Plasma and point-of-care blood glucoses were extracted from the electronic medical record. Change in serum glucose and the rate of DKA on SGLT2 inhibitor versus other antidiabetic drugs were examined as co-primary outcomes. RESULTS: We identified 103 patients meeting eligibility criteria with median follow-up of 92 days after starting alpelisib. When SGLT2 inhibitors were used to treat hyperglycemia, they were associated with a decrease in mean random glucose by -46 mg/dL (95% CI - 77 to - 15) in adjusted linear modeling. Five cases of DKA were identified, two occurring in patients on alpelisib plus SGLT2 inhibitor. Estimated incidence of DKA was: alpelisib plus SGLT2 inhibitor, 48 DKA cases per 100 patient-years (95% CI 6, 171); alpelisib with non-SGLT2 inhibitor antidiabetic drugs, 15 (95% CI 2, 53); alpelisib only, 4 (95% CI 0.1, 22). CONCLUSIONS: SGLT2 inhibitors are effective treatments for hyperglycemia in the setting of PI3K inhibition.

Comparative genomic analysis of PIK3R1-mutated and wild-type breast cancers.

PURPOSE: The PIK3R1 gene encodes the regulatory subunit-p85a-of the PI3K signaling complex. Prior studies have found that pathogenic somatic alterations in PIK3R1 are enriched in human breast cancers but the genomic landscape of breast cancer patients harboring PIK3R1 mutations has not been extensively characterized. METHODS: We retrospectively analyzed 6,009 patient records that underwent next-generation sequencing (NGS) using the Tempus xT solid tumor assay. All patients had breast cancer with known HER2 (+/-) and hormone receptor (HR; +/-) status and were classified according to the presence of PIK3R1 mutations including short variants and copy number alterations. RESULTS: The frequency of PIK3R1 mutations varied according to subtype: 6% in triple negative (TNBC, 89/1,475), 2% in HER2-/HR+ (80/3,893) and 2.3% in HER2+ (15/641) (p < 0.001). Co-mutations in PTEN, TP53 and NF1 were significantly enriched, co-mutations in PIK3CA were significantly less prevalent, and tumor mutational burden was significantly higher in PIK3R1-mutated HER2- samples relative to PIK3R1 wild-type. At the transcriptional-level, PIK3R1 RNA expression in HER2- disease was significantly higher in PIK3R1-mutated (excluding copy number loss) samples, regardless of subtype. CONCLUSION: This is the largest investigation of the PIK3R1 mutational landscape in breast cancer patients (n = 6,009). PIK3R1 mutations were more common in triple-negative breast cancer (~ 6%) than in HER2 + or HER2-/HR + disease (approximately 2%). While alterations in the PI3K/AKT pathway are often actionable in HER2-/HR + breast cancer, our study suggests that PIK3R1 could be an important target in TNBC as well.

Delineation of the phenotypes and genotypes of PIK3CA-related overgrowth spectrum in East asians.

PIK3CA-related overgrowth spectrum (PROS) is an umbrella term to describe a diverse range of developmental disorders. Research to date has predominantly emerged from Europe and North America, resulting in a notable scarcity of studies focusing on East Asian populations. Currently, the prevalence and distribution of PIK3CA variants across various genetic loci and their correlation with distinct phenotypes in East Asian populations remain unclear. This study aims to elucidate the phenotype-genotype correlations of PROS in East Asian populations. We presented the phenotypes and genotypes of 82 Chinese patients. Among our cohort, 67 individuals carried PIK3CA variants, including missense, frameshift, and splice variants. Six patients presented with both PIK3CA and an additional variant. Seven PIK3CA-negative patients exhibited overlapping PROS manifestations with variants in GNAQ, AKT1, PTEN, MAP3K3, GNA11, or KRAS. An integrative review of the literature pertaining to East Asian populations revealed that specific variants are uniquely associated with certain PROS phenotypes. Some rare variants were exclusively identified in cases of megalencephaly and diffuse capillary malformation with overgrowth. Non-hotspot variants with undefined oncogenicity were more common in CNS phenotypes. Diseases with vascular malformation were more likely to have variants in the helical domain, whereas phenotypes involving adipose/muscle overgrowth without vascular abnormalities predominantly presented variants in the C2 domain. Our findings underscore the unique phenotype-genotype patterns within the East Asian PROS population, highlighting the necessity for an expanded cohort to further elucidate these correlations. Such endeavors would significantly facilitate the development of PI3Kα selective inhibitors tailored for the East Asian population in the future.

Metabolic characteristics of granulosa cell tumor: role of PPARγ signaling†.

Granulosa cell tumors are relatively rare, posing challenges for comprehension and therapeutic development due to limited cases and preclinical models. Metabolic reprogramming, a hallmark of cancer, manifests in granulosa cell tumors with notable lipid accumulation and increased expression of peroxisome proliferator-activated receptor gamma (PPARγ), a key lipid metabolism regulator. The roles of these features, however, remain unclear. In our previous work, we established a granulosa cell tumor model in mice by introducing a constitutively active Pik3ca mutant in oocytes, enabling the study of predictable tumor patterns from postnatal day 50. In this study, we characterized metabolic alterations during tumorigenesis (postnatal day 8 to day 50) and tumor growth (day 50 to day 65) in this model and explored the impact of PPARγ antagonism on human granulosa cell tumor proliferation. The tumor exhibited significant lipid accumulation, with PPARγ and the proliferation marker Ki67 co-localizing at postnatal day 65. Transcriptome analysis demonstrates that pathways for lipid metabolism and mitochondrial oxidation are promoted during tumorigenesis and tumor growth, respectively. Overlappingly upregulated genes during tumorigenesis and tumor growth are associated with lipid metabolism pathways. Correspondingly, mouse granulosa cell tumor shows overexpression of peroxisome proliferator-activated receptor gamma and DGAT2 proteins at postnatal day 65. Furthermore, GW9662 reduces the proliferation of KGN human granulosa cell tumor cells and decreases the phosphorylation of AKT and SMAD3. Our findings identify metabolic abnormalities in ooPIK3CA* granulosa cell tumor model and suggest peroxisome proliferator-activated receptor gamma as a potential driver for primary granulosa cell tumor growth.

Integrating cfDNA liquid biopsy and organoid-based drug screening reveals PI3K signaling as a promising therapeutic target in colorectal cancer.

BACKGROUND: The current precision medicine relies on biomarkers, which are mainly obtained through next-generation sequencing (NGS). However, this model failed to find effective drugs for most cancer patients. This study tried to combine liquid biopsy with functional drug tests using organoid models to find potential drugs for cancer patients. METHODS: Colorectal cancer (CRC) patients were prospectively enrolled and blood samples were collected from patients before the start of treatment. Targeted deep sequencing of cfDNA samples was performed using a 14-gene panel. Gastrointestinal (GI) cancer organoids were established and PI3K and mTOR inhibitors were evaluated on organoid models. RESULTS: A total of 195 mutations were detected across 58 cfDNA samples. The most frequently mutated genes were KRAS, TP53, PIK3CA, and BRAF, all of which exhibited higher mutation rates than tissue biopsy. Although 81% of variants had an allele frequency of less than 1%, certain mutations in KRAS, TP53, and SMAD4 had high allele frequencies exceeding 10%. Notably, among the seven patients with high allele frequency mutations, six had metastatic tumors, indicating that a high allele frequency of ctDNA could potentially serve as a biomarker of later-stage cancer. A high rate of PIK3CA mutation (31 out of 67, or 46.3%) was discovered in CRC patients, suggesting possible tumor progression mechanisms and targeted therapy opportunities. To evaluate the value of anti PI3K strategy in GI cancer, different lines of GI cancer organoids were established. The organoids recapitulated the morphologies of the original tumors. Organoids were generally insensitive to PI3K inhibitors. However, CRC-3 and GC-4 showed response to mTOR inhibitor Everolimus, and GC-3 was sensitive to PI3Kδ inhibitor Idelalisib. The CRC organoid with a PIK3CA mutation showed greater sensitivity to the PI3K inhibitor Alpelisib than wildtype organoids, suggesting potential treatment options for the corresponding patients. CONCLUSION: Liquid biopsy holds significant promise for improving precision treatment and tumor prognosis in colorectal cancer patients. The combination of biomarker-based drug prediction with organoid-based functional drug sensitivity assay may lead to more effective cancer treatment.

Molecular Basis and Diagnostic Approach to Isolated and Syndromic Lateralized Overgrowth in Childhood.

OBJECTIVE: To demonstrate a high-yield molecular diagnostic workflow for lateralized overgrowth (LO), a congenital condition with abnormal enlargement of body parts, and to classify it by molecular genetics. STUDY DESIGN: We categorized 186 retrospective cases of LO diagnosed between 2003 and 2023 into suspected Beckwith-Wiedemann spectrum, PIK3CA-related overgrowth spectrum (PROS), vascular overgrowth, or isolated LO, based on initial clinical assessments, to determine the appropriate first-tier molecular tests and tissue for analysis. Patients underwent testing for 11p15 epigenetic abnormalities or somatic variants in genes related to PI3K/AKT/mTOR, vascular proliferation, and RAS-MAPK cascades using blood or skin DNA. For cases with negative initial tests, a sequential cascade molecular approach was employed to improve diagnostic yield. RESULTS: This approach led to a molecular diagnosis in 54% of cases, 89% of cases consistent with initial clinical suspicions, and 11% reclassified. Beckwith-Wiedemann spectrum was the most common cause, with 43% of cases exhibiting 11p15 abnormalities. PIK3CA-related overgrowth spectrum had the highest confirmation rate, with 74% of clinically diagnosed patients showing a PIK3CA variant. Vascular overgrowth demonstrated significant clinical overlap with other syndromes. A molecular diagnosis of isolated LO proved challenging, with only 21% of cases classifiable into a specific condition. CONCLUSIONS: LO is underdiagnosed from a molecular viewpoint and to date has had no diagnostic guidelines, which is crucial for addressing potential cancer predisposition, enabling precision medicine treatments, and guiding management. This study sheds light on the molecular etiology of LO, highlighting the importance of a tailored diagnostic approach and of selecting appropriate testing to achieve the highest diagnostic yield.

Mucinous cystadenocarcinoma of the breast harbours TRPS1 expressions and PIK3CA alterations.

AIMS: Breast mucinous cystadenocarcinoma (BMCA) is a rare tumour recently recognised as a distinct entity by the World Health Organisation Tumour Classification Series. BMCA is a triple-negative tumour that lacks specific immunohistochemical markers; therefore, distinguishing it from mimickers such as ovarian and pancreatic cystadenocarcinomas requires careful clinicopathological correlation. Due to its rarity, little is known about the molecular alterations that underlie BMCA. METHODS AND RESULTS: In this study, we used immunohistochemical staining methods to investigate TRPS1 (trichorhinophalangeal syndrome type 1) expression in BMCA and compare it to expression in ovarian and pancreatic mucinous cystadenocarcinomas. We also collected tumour samples from three BMCA patients for molecular analysis by MALDI-TOF mass spectrometry, real-time polymerase chain reaction, whole exome sequencing and fluorescence in-situ hybridisation. TRPS1 immunoreactivity was found only in BMCA tumour cells and not in the ovarian and pancreatic counterparts. One of the three BMCA tumours also showed a PIK3CA hot-spot mutation, which was confirmed by whole genome next-generation sequencing (NGS). No KRAS, NRAS, BRAF or AKT mutations were found. CONCLUSIONS: To our knowledge, this is the first demonstration of TRPS1 expression in BMCA patients and the first identification of a PIK3CA hotspot mutation in these tumours. These findings provide insights into the molecular mechanisms underlying BMCA tumorigenesis and suggest a potential drug target for this rare and poorly understood cancer.

DDX19A promotes gastric cancer cell proliferation and migration by activating the PI3K/AKT pathway.

BACKGROUND: DEAD-box RNA helicase 19 A (DDX19A) is overexpressed in cervical squamous cell carcinoma. However, its role in gastric cancer remains unclear. The present study aimed to explore the role and underlying mechanism of DDX19A in the development of gastric cancer. METHODS: The expression of DDX19A in gastric cancer and paracancerous tissues was evaluated through quantitative polymerase chain reaction, western blotting, and immunohistochemical staining. The biological functions of DDX19A in gastric cancer were determined using CCK8, plate colony-forming, and Transwell migration assays. The specific mechanism of DDX19A in gastric cancer cells was studied using western blotting, RNA-binding protein immunoprecipitation, mRNA half-life detection, and nuclear and cytoplasmic RNA isolation. RESULTS: DDX19A was highly expressed in gastric cancer and positively associated with malignant clinicopathological features and poor prognosis. Additionally, DDX19A promoted gastric cancer cell proliferation, migration, and epithelial-mesenchymal transition phenotypes. Mechanistically, DDX19A activated the PI3K/AKT pathway by upregulating phosphatidylinositol-3-kinase (PIK3CA) expression. Furthermore, DDX19A interacted with PIK3CA mRNA, stabilized it, and facilitated its export from the nucleus. CONCLUSIONS: Our study reveals a novel mechanism whereby DDX19A promotes the proliferation and migration of gastric cancer cells by enhancing the stability and nuclear export of PIK3CA mRNA, thereby activating the PI3K/AKT pathway.

Molecular characterization of 13 patients with PIK3CA-related overgrowth spectrum using a targeted deep sequencing approach.

Activating variants in the PIK3CA gene cause a heterogeneous spectrum of disorders that involve congenital or early-onset segmental/focal overgrowth, now referred to as PIK3CA-related overgrowth spectrum (PROS). Historically, the clinical diagnoses of patients with PROS included a range of distinct syndromes, including CLOVES syndrome, dysplastic megalencephaly, hemimegalencephaly, focal cortical dysplasia, Klippel-Trenaunay syndrome, CLAPO syndrome, fibroadipose hyperplasia or overgrowth, hemihyperplasia multiple lipomatosis, and megalencephaly capillary malformation-polymicrogyria (MCAP) syndrome. MCAP is a sporadic overgrowth disorder that exhibits core features of progressive megalencephaly, vascular malformations, distal limb malformations, cortical brain malformations, and connective tissue dysplasia. In 2012, our research group contributed to the identification of predominantly mosaic, gain-of-function variants in PIK3CA as an underlying genetic cause of the syndrome. Mosaic variants are technically more difficult to detect and require implementation of more sensitive sequencing technologies and less stringent variant calling algorithms. In this study, we demonstrated the utility of deep sequencing using the Illumina TruSight Oncology 500 (TSO500) sequencing panel in identifying variants with low allele fractions in a series of patients with PROS and suspected mosaicism: pathogenic, mosaic PIK3CA variants were identified in all 13 individuals, including 6 positive controls. This study highlights the importance of screening for low-level mosaic variants in PROS patients. The use of targeted panels with deep sequencing in clinical genetic testing laboratories would improve diagnostic yield and accuracy within this patient population.

Microcystic lymphatic malformations in Turner syndrome are due to somatic mosaicism of PIK3CA.

Turner syndrome (45,X) is caused by a complete or partial absence of a single X chromosome. Vascular malformations occur due to abnormal development of blood and/or lymphatic vessels. They arise from either somatic or germline pathogenic variants in the genes regulating growth and apoptosis of vascular channels. Aortic abnormalities are a common, known vascular anomaly of Turner syndrome. However, previous studies have described other vascular malformations as a rare feature of Turner syndrome and suggested that vascular abnormalities in individuals with Turner syndrome may be more generalized. In this study, we describe two individuals with co-occurrence of Turner syndrome and vascular malformations with a lymphatic component. In these individuals, genetic testing of the lesional tissue revealed a somatic pathogenic variant in PIK3CA-a known and common cause of lymphatic malformations. Based on this finding, we conclude that the vascular malformations presented here and likely those previously in the literature are not a rare part of the clinical spectrum of Turner syndrome, but rather a separate clinical entity that may or may not co-occur in individuals with Turner syndrome.

Alpelisib for PIK3CA-mutated advanced gynecological cancers: First clues of clinical activity.

OBJECTIVE: Recurrent gynecological tumors (e.g., endometrial, and ovarian cancers) are incurable diseases; therefore, new treatment options are urgently needed. The PTEN-AKT-PI3K pathway is frequently altered in these tumors, representing a potential treatment target. Alpelisib is an α-specific PI3K inhibitor approved in PIK3CA-mutated advanced breast cancer. We report outcomes from a large series of patients with PIK3CA-mutated gynecological cancers prospectively treated with alpelisib within a controlled program. METHODS: From April 2021 to December 2022, 36 patients with PIK3CA-mutated advanced gynecological cancers received alpelisib 300 mg orally once daily. Objective response (ORR) and disease control (DCR) rates provided measure of the antitumor activity of alpelisib, the primary objective of the study. RESULTS: Included patients had endometrial (17/36 [47%]), ovarian (10/36 [28%]), or other gynecological cancers (9/36 [25%]). Most patients had received 2-3 prior systemic treatments (endometrial, 47·2%; ovarian, 60%; other, 56%), and presented with visceral metastases at baseline (82%, 70%, and 56%, respectively). Overall, 17 different PIK3CA mutations were found, including 53% in the kinase domain (most commonly H1047R) and 36% in the helical domain (most commonly E545K). Overall, the ORR was 28% and DCR was 61%, with the greatest benefit observed in patients with endometrial cancer (35% and 71%, respectively). CONCLUSION: Alpelisib represents an active treatment option in patients with recurrent gynecological cancers harboring a PIK3CA mutation. These findings support the need of biomarker-driven randomized trials of PI3K inhibitors in gynecological cancers.

PIK3CA mutation as an acquired resistance driver to EGFR-TKIs in non-small cell lung cancer: Clinical challenges and opportunities.

Epithelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) have significantly enhanced the treatment outcomes in non-small cell lung cancer (NSCLC) patients harboring EGFR mutations. However, the occurrence of acquired resistance to EGFR-TKIs is an unavoidable outcome observed in these patients. Disruption of the PI3K/AKT/mTOR signaling pathway can contribute to the emergence of resistance to EGFR TKIs in lung cancer. The emergence of PIK3CA mutations following treatment with EGFR-TKIs can lead to resistance against EGFR-TKIs. This review provides an overview of the current perspectives regarding the involvement of PI3K/AKT/mTOR signaling in the development of lung cancer. Furthermore, we outline the state-of-the-art therapeutic strategies targeting the PI3K/AKT/mTOR signaling pathway in lung cancer. We highlight the role of PIK3CA mutation as an acquired resistance mechanism against EGFR-TKIs in EGFR-mutant NSCLC. Crucially, we explore therapeutic strategies targeting PIK3CA-mediated resistance to EGFR TKIs in lung cancer, aiming to optimize the effectiveness of treatment.

Preclinical Models of Anal Cancer Combined-Modality Therapy.

INTRODUCTION: There have been no significant changes in anal cancer treatment options in 4 decades. In this study, we highlight two preclinical models designed to assess anal cancer treatments. MATERIALS AND METHODS: Transgenic K14E6/E7 mice were treated with 7, 12-dimethylbenz(a)anthracene until anal tumors developed. Mice were treated with localized radiation in addition to chemotherapy (combined-modality therapy [CMT]) and compared to no treatment control (NTC). K14E6/E7 mouse anal spheroids with and without Pik3ca mutations were isolated and treated with vehicle, LY3023414 (LY3) (a drug previously shown to be effective in cancer prevention), CMT, or CMT + LY3. RESULTS: In the in vivo model, there was a significant increase in survival in the CMT group compared to the NTC group (P = 0.0392). In the ex vivo model, there was a significant decrease in the mean diameter of CMT and CMT + LY3-treated spheroids compared to vehicle (P ≤ 0.0001). For LY3 alone compared to vehicle, there was a statistically significant decrease in spheroid size in the K14E6/E7 group without mutation (P = 0.0004). CONCLUSIONS: We have provided proof of concept for two preclinical anal cancer treatment models that allow for the future testing of novel therapies for anal cancer.