Inhibition Of Phosphatidylinositol 3-kinase Pathway Research Articles

Duvelisib with docetaxel for patients with anti-PD-1 refractory, recurrent or metastatic head and neck squamous cell carcinoma.

Treatments after anti-PD-1 therapy for patients with recurrent, metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) are limited. Blocking phosphatidylinositol 3-kinase (PI3K) signaling may lead to tumor immunomodulation and enhanced taxane sensitivity. This phase 2 trial evaluated dual, selective PI3Kδ/γ inhibition with docetaxel in patients with anti-PD-1 refractory R/M HNSCC. Patients received duvelisib (25 mg orally twice daily) with docetaxel (75 mg/m2 IV) every 21-days. The primary endpoint was overall response rate (ORR) (RECISTv1.1), employing a Simon two-stage design. Secondary endpoints: safety, progression-free survival (PFS), overall survival (OS); exploratory endpoints: correlating immunologic and genomic parameters with outcomes. From 11/1/21 to 10/10/23, 26 patients enrolled (median age: 64, 96% men, 54% with HPV+ disease; primary site: 12 oropharynx, 11 oral cavity, 3 larynx/hypopharynx. Best ORR was 19% (5/26) (95%CI: 6.8-40.7%), all were partial responses (median duration: 5.1 months [0.7-15.5]); 46% (12/26) exhibited stable disease and 32% (8/26) progression (1 unevaluable). Two patients remain on-treatment at data cutoff; 25% (6/24) came off for toxicity. Grade 3+ treatment-related adverse events were observed in 50% (13/26), most often elevated liver function tests (6, 23%). No deaths were treatment related. At median follow-up of 6.5 months (0.7-26), median PFS: 2.8 months (95%CI: 1.9-7.0); 17/26 patients had died. Median OS: 10.2 months (95%CI: 6.7-15.9), favoring HPV-negative patients. Greater tumor CD3+/CD8+ T cell infiltration trended with improved outcomes. We report a favorable response rate when combining a selective PI3K pathway inhibitor and taxane in patients with anti-PD-1 refractory HNSCC. gov: NCT05057247.

The PI3K/AKT/mTOR signaling pathway in breast cancer: Review of clinical trials and latest advances.

Breast cancer (BC) is the most commonly diagnosed cancer and the leading cause of cancer mortality in women. As the phosphatidylinositol 3-kinase (PI3K) signaling pathway is involved in a wide range of physiological functions of cells including growth, proliferation, motility, and angiogenesis, any alteration in this axis could induce oncogenic features; therefore, numerous preclinical and clinical studies assessed agents able to inhibit the components of this pathway in BC patients. To the best of our knowledge, this is the first study that analyzed all the registered clinical trials investigating safety and efficacy of the PI3K/AKT/mTOR axis inhibitors in BC. Of note, we found that the trends of PI3K inhibitors in recent years were superior as compared with the inhibitors of either AKT or mTOR. However, most of the trials entering phase III and IV used mTOR inhibitors (majorly Everolimus) followed by PI3K inhibitors (majorly Alpelisib) leading to the FDA approval of these drugs in the BC context. Despite favorable efficacies, our analysis shows that the majority of trials are utilizing PI3K pathway inhibitors in combination with hormone therapy and chemotherapy; implying monotherapy cannot yield huge clinical benefits, at least partly, due to the activation of compensatory mechanisms. To emphasize the beneficial effects of these inhibitors in combined-modal strategies, we also reviewed recent studies which investigated the conjugation of nanocarriers with PI3K inhibitors to reduce harmful toxicities, increase the local concentration, and improve their efficacies in the context of BC therapy.

The Antimicrobial Peptide Esculentin-1a(1-21)NH2 Stimulates Wound Healing by Promoting Angiogenesis through the PI3K/AKT Pathway.

Delayed wound healing is a persistent medical problem mainly caused by decreased angiogenesis. Esculentin-1a(1-21)NH2 [Esc-1a(1-21)NH2], has broad-spectrum antibacterial properties which comes from frog skins. It has shown promise as a treatment for wound healing. However, its effects on angiogenesis as well as the mechanism by which esc-1a(1-21)NH2 enhanced wound healing remained unclear. In this study, we analyzed the structural properties and biocompatibility of esc-1a(1-21)NH2 and evaluated its effect on wound closure using a full-thickness excision model in mice. Our results showed that esc-1a(1-21)NH2 significantly accelerated wound healing by increasing collagen deposition and angiogenesis, characterized by elevated expression levels of platelet, endothelial cell adhesion molecule-1 (CD31) and proliferating cell nuclear antigen (PCNA). Furthermore, the angiogenic activity of esc-1a(1-21)NH2 was confirmed in vitro by various assays. Esc-1a(1-21)NH2 significantly promoted cell migration and cell proliferation in human umbilical vein vascular endothelial cells (HUVECs) via activation of the phosphatidylinositol 3'-kinase (PI3K)/protein kinase B (AKT) pathway, and upregulated the expression of CD31 at both mRNA and protein levels. The effect of esc-1a(1-21)NH2 on angiogenesis was diminished by LY294002, a PI3K pathway inhibitor. Taken together, this study demonstrates that esc-1a(1-21)NH2 accelerates wound closure in mice by promoting angiogenesis via the PI3K/AKT signaling pathway, suggesting its effective application in the treatment of wound healing.

NSCLC Cells Resistance to PI3K/mTOR Inhibitors Is Mediated by Delta-6 Fatty Acid Desaturase (FADS2)

Hyperactivation of the phosphatidylinositol-3-kinase (PI3K) pathway is one of the most common events in human cancers. Several efforts have been made toward the identification of selective PI3K pathway inhibitors. However, the success of these molecules has been partially limited due to unexpected toxicities, the selection of potentially responsive patients, and intrinsic resistance to treatments. Metabolic alterations are intimately linked to drug resistance; altered metabolic pathways can help cancer cells adapt to continuous drug exposure and develop resistant phenotypes. Here we report the metabolic alterations underlying the non-small cell lung cancer (NSCLC) cell lines resistant to the usual PI3K-mTOR inhibitor BEZ235. In this study, we identified that an increased unsaturation degree of lipid species is associated with increased plasma membrane fluidity in cells with the resistant phenotype and that fatty acid desaturase FADS2 mediates the acquisition of chemoresistance. Therefore, new studies focused on reversing drug resistance based on membrane lipid modifications should consider the contribution of desaturase activity.

P-471 Effect of verteporfin, an inhibitor of Hippo signaling pathway, on chemotherapy-induced follicle activation and survival of neonatal mice ovaries in vitro

Abstract Study question Does verteporfin, an inhibitor of Hippo signaling pathway, influence mechanisms involved in chemotherapy-induced follicle activation and survival in vitro? Summary answer Verteporfin acts directly on cell growth and indirectly on phosphatidylinositol-3-kinase (PI3K) signaling pathway, but does not prevent chemotherapy-induced follicle activation, although moderates 4-hydroperoxycylophosphamide (4HC) gonadotoxicity. What is known already Cryopreservation of ovarian tissue is an experimental technique aimed at prepubertal patients in need of chemotherapy. To optimize this method, in vitro culture of cryopreserved tissue is being investigated. However, this process leads to a massive loss of primordial follicles due to their spontaneous activation. Inhibition of PI3K pathway, the major signaling pathway involved in follicle activation, is moderately efficient to prevent chemotherapy-induced follicle activation. Recently, the effect of Hippo pathway disruption due to sectioning on follicle activation has been described, suggesting that verteporfin can inhibit Hippo pathway-induced follicle activation. Study design, size, duration Ovaries collected from post-natal day 3 and/or 4 (PND3/4) mice were used for this study. Whole and cut ovaries were cultured in vitro for 3 hours to validate the effect of verteporfin on Hippo pathway disruption. Whole ovaries were cultured in vitro for 24 and 48 hours to assess the impact of verteporfin and/or chemotherapy (4HC, 10 µM) exposure on primordial follicle activation and survival. At least 3 ovaries were used for each condition. Participants/materials, setting, methods The inhibitory and toxic effects of verteporfin on whole and cut ovaries were investigated by analysing the expression of genes involved in Hippo and PI3K pathways, as well as in apoptosis (RT-qPCR). The effect of co-treatment with verteporfin and 4HC on follicle activation and survival was assessed by histological analysis (immunohistochemistry and TUNEL staining), gene expression (RT-qPCR) and protein analysis (immunostaining and Western Blot) to investigate signaling pathways, cell proliferation and apoptosis. Main results and the role of chance The inhibitory effect of verteporfin on Hippo pathway disruption induced by sectioning was achieved on ovaries exposed to 3 µM of verteporfin despite slightly increasing apoptosis at 3 hours of culture. Verteporfin was able to slightly prevent the effect of chemotherapy on Hippo pathway, but its impact was limited by the time of culture. Surprisingly, verteporfin also acted indirectly on PI3K pathway by significantly decreasing the level of downstream phosphorylated proteins. However, in presence of chemotherapy, verteporfin was not sufficient to prevent the effect of 4HC on this pathway. Alone, verteporfin also significantly decreased granulosa cells proliferation, depending on the time of culture: although reducing cell growth at 24 hours of culture, this effect was not observed after 48 hours of in vitro culture. The inhibitor was not able to prevent apoptosis induced by 4HC at 24 hours of culture. However, at 48 hours of culture, the decrease in the number of positive TUNEL follicles in the co-treatment condition compared to ovaries treated with chemotherapy alone suggested a potential positive effect of verteporfin to prevent chemotherapy-induced gonadotoxicity. Limitations, reasons for caution The main limitation of this study is the experimental model used. Although mouse is a strong and reliable model, it lacks certain characteristics specific to human. Investigating other timepoints of culture and exposition, as well as different doses of verteporfin, might benefit the study. Wider implications of the findings Our study supports Hippo and PI3K pathways interaction during in vitro follicle activation. Despite verteporfin does not appear to be an inhibitor of interest, testing another Hippo inhibitor or combining Hippo and PI3K pathways inhibitors could be investigated to control follicle activation during in vitro culture of ovarian tissue. Trial registration number Not applicable

At a crossroads: how to translate the roles of PI3K in oncogenic and metabolic signalling into improvements in cancer therapy.

Numerous agents targeting various phosphatidylinositol 3-kinase (PI3K) pathway components, including PI3K, AKT and mTOR, have been tested in oncology clinical trials, resulting in regulatory approvals for the treatment of selected patients with breast cancer, certain other solid tumours or particular haematological malignancies. However, given the prominence of PI3K signalling in cancer and the crucial role of this pathway in linking cancer growth with metabolism, these clinical results could arguably be improved upon. In this Review, we discuss past and present efforts to overcome the somewhat limited clinical efficacy of PI3Kα pathway inhibitors, including optimization of inhibitor specificity, patient selection and biomarkers across cancer types, with a focus on breast cancer, as well as identification and abrogation of signalling-related and metabolic mechanisms of resistance, and interventions to improve management of prohibitive adverse events. We highlight the advantages and limitations of laboratory-based model systems used to study the PI3K pathway, and propose technologies and experimental inquiries to guide the future clinical deployment of PI3K pathway inhibitors in the treatment of cancer.

Gallic acid promotes the in vitro development of sheep secondary isolated follicles involving the phosphatidylinositol 3-kinase pathway

This study was conducted to evaluate the effect of addition of gallic acid as the single antioxidant to the base medium for in vitro culture of sheep secondary follicles and if the phosphatidylinositol 3-kinase (PI3K) pathway is involved in the action of gallic acid. Secondary follicles were isolated and cultured for 12 days in α-MEM supplemented with bovine serum albumin (BSA), insulin, glutamine, hypoxanthine, transferrin, selenium, and ascorbic acid (control medium: α-MEM+) or in α-MEM supplemented with BSA, insulin, glutamine, hypoxanthine and different concentrations of gallic acid (25, 50 or 100 μM), thus replacing transferrin, selenium and ascorbic acid in the medium. Follicle morphology, glutathione (GSH), and mitochondrial activity, and meiotic resumption were evaluated. Furthermore, inhibition of PI3K pathway was performed by pretreatment with LY294002. After 12 days of culture, the follicle survival in a medium containing 100 μM gallic acid was similar (P > 0.05) to α-MEM+ and greater (P < 0.05) compared with other gallic acid concentrations. Antrum formation, follicle diameter, GSH, and mitochondrial activity, and meiotic resumption, however, were greater (P < 0.05) when 100 μM gallic acid was included in the α-MEM+ culture medium compared with the control medium. Furthermore, LY294002 inhibited (P < 0.05) follicle survival, development, and meiotic resumption stimulated by 100 μM gallic acid. In conclusion, concentration of 100 μM of gallic acid can be a substitute for transferrin, selenium, and ascorbic acid in the base medium during in vitro culture of sheep secondary follicles, inducing follicle development likely through the PI3K pathway.

NVP-BEZ235 or JAKi Treatment leads to decreased survival of examined GBM and BBC cells

Cancer cells almost universally harbor constitutively active Phosphatidylinositol-3 Kinase (PI3K) Pathway activity via mutation of key signaling components and/or epigenetic mechanisms. Scores of PI3K Pathway inhibitors are currently under investigation as putative chemotherapeutics. However, feedback and stem cell mechanisms induced by PI3K Pathway inhibition can lead to reduced treatment efficacy. To address therapeutic barriers, we examined whether JAKi would reduce stem gene expression in a setting of PI3K Pathway inhibition in order to improve treatment efficacy. We targeted the PI3K Pathway with NVP-BEZ235 (dual PI3K and mTOR inhibitor) in combination with the Janus Kinase inhibitor JAKi in glioblastoma (GBM) and basal-like breast cancer (BBC) cell lines. We examined growth, gene expression, and apoptosis in cells treated with NVP-BEZ235 and/or JAKi. Growth and recovery assays showed no significant impact of dual treatment with NVP-BEZ235/JAKi compared to NVP-BEZ235 treatment alone. Gene expression and flow cytometry revealed that single and dual treatments induced apoptosis. Stem gene expression was retained in dual NVP-BEZ235/JAKi treatment samples. Future in vivo studies may give further insight into the impact of combined NVP-BEZ235/JAKi treatment in GBM and BBC.

Abstract B07: TAK228 enhances antitumor activity of eribulin in triple-negative breast cancer

Abstract Background: Phosphatase and tensin homologue deleted from chromosome 10 (PTEN) negatively regulates the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway. Triple-negative breast cancers (TNBC) are often PTEN-deficient, making mTOR a compelling target. We evaluated the efficacy of catalytic mTOR inhibitor TAK228 alone and in combination with eribulin in TNBC. Methods: We tested TAK228 in combination with eribulin in a panel of TNBC cell lines with cell proliferation assays. Western blot analysis was performed to assess PTEN status and PI3K pathway inhibition. In vivo, antitumor efficacy of TAK228 as a single agent as well as in combination with eribulin was evaluated. Results: Five of eight triple-negative breast cell lines were sensitive to TAK228, independent of PIK3CA/PTEN status. Western blotting demonstrated inhibition of mTORC1/2 signaling as demonstrated by decreased phospho-AKT, phospho-S6 and phospho-4EBP1. In vitro, TAK228 was synergistic with eribulin in all eight TNBC cell lines. The combination of TAK228 and eribulin did not enhance apoptosis but increased G2/M growth arrest (p&amp;lt;0.001). In vivo, TAK228 led to modest growth inhibition in TNBC derived xenografts with no tumor regression observed. In two TNBC PDXs with PTEN loss, one with intrinsic eribulin sensitivity, another eribulin resistance, TAK228 in combination with eribulin did not enhance in vivo efficacy. In a third PTEN-negative TNBC model, eribulin alone achieved disease stabilization, but the combination of TAK228 and eribulin led to significantly smaller tumor volumes compared to eribulin alone (p&amp;lt;0.0001). Conclusion: TAK228 enhanced the antitumor efficacy of eribulin in TNBC models in vitro and enhanced in vivo activity in selected models. Further study is needed to determine the potential of this combination and optimal patient selection strategies. Citation Format: Nicci Owusu-Brackett, Kurt W. Evans, Argun Akcakanat, Erkan Yuca, Ecaterina Ileana Dumbrava, Filip Janku, Funda Meric-Bernstam. TAK228 enhances antitumor activity of eribulin in triple-negative breast cancer [abstract]. In: Proceedings of the AACR Special Conference on Targeting PI3K/mTOR Signaling; 2018 Nov 30-Dec 8; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Res 2020;18(10_Suppl):Abstract nr B07.

3O Efficacy of the triple combination of Estrogen Receptor, CDK4/6 and PI3K pathway inhibitors in ex-vivo models of breast cancer

Activation of the Phosphatidylinositol 3-kinase (PI3K) pathway is common in Estrogen receptor (ER)-positive breast cancer (BC) and it has been associated with resistance to endocrine therapies (ET). The crosstalk between the Cyclin-dependent kinase 4/6 (CDK4/6) and PI3K pathways represents a strong rationale for co-targeting both axes to inhibit tumor growth. Moreover, combined treatment with PI3K and CDK4/6 inhibitors has been shown to overcome CDK4/6 inhibitor resistance in BC cells. We investigated the triple combination of ER, CDK4/6, and PI3K pathway inhibitors in ex vivo BC models as a novel strategy to overcome endocrine and CDK4/6-resistance.

Activating AKT1 and PIK3CA Mutations in Metastatic Castration-Resistant Prostate Cancer

BackgroundActivating mutations in AKT1 and PIK3CA are undercharacterised in metastatic castration-resistant prostate cancer (mCRPC), but are linked to activation of phosphatidylinositol 3-kinase (PI3K) signalling and sensitivity to pathway inhibitors in other cancers. ObjectiveTo determine the prevalence, genomic context, and clinical associations of AKT1/PIK3CA activating mutations in mCRPC. Design, setting, and participantsWe analysed targeted cell-free DNA (cfDNA) sequencing data from 599 metastatic prostate cancer patients with circulating tumour DNA (ctDNA) content above 2%. Outcome measurements and statistical analysisIn patients with AKT1/PIK3CA mutations, cfDNA was subjected to PTEN intron sequencing and matched diagnostic tumour tissue was analysed when possible. Results and limitationsOf the patients, 6.0% (36/599) harboured somatic clonal activating mutation(s) in AKT1 or PIK3CA. Mutant allele-specific imbalance was common. Clonal mutations in mCRPC ctDNA were typically detected in pretreatment primary tissue and were consistent across serial ctDNA collections. AKT1/PIK3CA-mutant mCRPC had fewer androgen receptor (AR) gene copies than AKT1/PIK3CA wild-type mCRPC (median 4.7 vs 10.3, p = 0.003). AKT1 mutations were mutually exclusive with PTEN alterations. Patients with and without AKT1/PIK3CA mutations showed similar clinical outcomes with standard of care treatments. A heavily pretreated mCRPC patient with an AKT1 mutation experienced a 50% decline in prostate-specific antigen with Akt inhibitor (ipatasertib) monotherapy. Ipatasertib also had a marked antitumour effect in a patient-derived xenograft harbouring an AKT1 mutation. Limitations include the inability to assess AKT1/PIK3CA correlatives in ctDNA-negative patients. ConclusionsAKT1/PIK3CA activating mutations are relatively common and delineate a distinct mCRPC molecular subtype with low-level AR copy gain. Clonal prevalence and evidence of mutant allele selection propose PI3K pathway dependency in selected patients. The use of cfDNA screening enables prospective clinical trials to test PI3K pathway inhibitors in this population. Patient summaryOf advanced prostate cancer cases, 6% have activating mutations in the genes AKT1 or PIK3CA. These mutations can be identified using a blood test and may help select patients suitable for clinical trials of phosphatidylinositol 3-kinase inhibitors.

Torin2 Exploits Replication and Checkpoint Vulnerabilities to Cause Death of PI3K-Activated Triple-Negative Breast Cancer Cells.

Frequent mutation of PI3K/AKT/mTOR signaling pathway genes in human cancers has stimulated large investments in targeted drugs but clinical successes are rare. As a result, many cancers with high PI3K pathway activity, such as triple-negative breast cancer (TNBC), are treated primarily with chemotherapy. By systematically analyzing responses of TNBC cells to a diverse collection of PI3K pathway inhibitors, we find that one drug, Torin2, is unusually effective because it inhibits both mTOR and other PI3K-like kinases (PIKKs). In contrast to mTOR-selective inhibitors, Torin2 exploits dependencies on several kinases for S-phase progression and cell-cycle checkpoints, thereby causing accumulation of single-stranded DNA and death by replication catastrophe or mitotic failure. Thus, Torin2 and its chemical analogs represent a mechanistically distinct class of PI3K pathway inhibitors that are uniquely cytotoxic to TNBC cells. This insight could be translated therapeutically by further developing Torin2 analogs or combinations of existing mTOR and PIKK inhibitors.

The Role of the LY294002 - A Non-Selective Inhibitor of Phosphatidylinositol 3-Kinase (PI3K) Pathway- in Cell Survival and Proliferation in Cell Line SCC-25.

The activation of PI3K further activates subsequent regulatory pathways, which are activated via AKT phosphorylation. AKT is closely related to the Bcl-2 family, a protein known to be involved in cell survival. AKT also has a relationship with inflammatory and glycolytic mediators. The present work aimed to evaluate the relationship between the PI3K/AKT pathway, cell survival/proliferation, inflammatory mediators and the glycolytic pathway in oral squamous cell carcinoma. All experiments were performed in the SCC25 oral squamous cell carcinoma cell line. In the presence or absence of PI3K pathway inhibitors, we analyzed the protein expression of pAKT and AKT; X-linked inhibitor of apoptosis protein; Bcl-2-associated death promoter; Bcl-2-like protein two inhibitor; cyclooxygenase 1; cyclooxygenase-2; and glycoprotein-associated glucose transporter 1. For the functional characterization of treated or untreated cells, we also performed matrix invasion assays, cell migration assays, and cell proliferation assays. Our results demonstrated that activation of the PI3K/AKT pathway is directly related to members of the Bcl-2 family and GLUT1, but not the inflammatory mediators COX1 and COX2. Our data suggest that the PI3K/AKT pathway is related to cell survival and proliferation in oral squamous cell carcinoma through its interaction with Bcl-2 family members.

Guanosine prevents oxidative damage and glutamate uptake impairment induced by oxygen/glucose deprivation in cortical astrocyte cultures: involvement of A1 and A2A adenosine receptors and PI3K, MEK, and PKC pathways.

Glial cells are involved in multiple cerebral functions that profoundly influence brain tissue viability during ischemia, and astrocytes are the main source of extracellular purines as adenosine and guanosine. The endogenous guanine-based nucleoside guanosine is a neuromodulator implicated in important processes in the brain, such as modulation of glutamatergic transmission and protection against oxidative and inflammatory damage. We evaluated if the neuroprotective effect of guanosine is also observed in cultured cortical astrocytes subjected to oxygen/glucose deprivation (OGD) and reoxygenation. We also assessed the involvement of A1 and A2A adenosine receptors and phosphatidylinositol-3 kinase (PI3K), MAPK, and protein kinase C (PKC) signaling pathways on the guanosine effects. OGD/reoxygenation decreased cell viability and glutamate uptake and increased reactive oxygen species (ROS) production in cultured astrocytes. Guanosine treatment prevented these OGD-induced damaging effects. Dipropyl-cyclopentyl-xanthine (an adenosine A1 receptor antagonist) and 4-[2-[[6-amino-9-(N-ethyl-β-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl] benzenepropanoic acid hydrochloride (an adenosine A2A receptor agonist) abolished guanosine-induced protective effects on ROS production, glutamate uptake, and cell viability. The PI3K pathway inhibitor 2-morpholin-4-yl-8-phenylchromen-4-one, the extracellular-signal regulated kinase kinase (MEK) inhibitor 2'-amino-3'-methoxyflavone, or the PKC inhibitor chelerythrine abolished the guanosine effect of preventing OGD-induced cells viability reduction. PI3K inhibition partially prevented the guanosine effect of reducing ROS production, whereas MEK and PKC inhibitions prevented the guanosine effect of restoring glutamate uptake. The total immunocontent of the main astrocytic glutamate transporter glutamate transporter-1 (GLT-1) was not altered by OGD and guanosine. However, MEK and PKC inhibitions also abolished the guanosine effect of increasing cell-surface expression of GLT-1 in astrocytes subjected to OGD. Then, guanosine prevents oxidative damage and stimulates astrocytic glutamate uptake during ischemic events via adenosine A1 and A2A receptors and modulation of survival signaling pathways, contributing to microenvironment homeostasis that culminates in neuroprotection.

PIPA: A phase Ib study of selective ß-isoform sparing phosphatidylinositol 3-kinase (PI3K) inhibitor taselisib (T) plus palbociclib (P) in patients (pts) with advanced solid cancers—Safety, tolerability, pharmacokinetic (PK), and pharmacodynamic (PD) analysis of the doublet combination.

3087 Background: Oncogenic hyperactivation of the PI3K pathway is common in multiple cancers, with preclinical data showing that CDK4/6 inhibitors sensitise PIK3CA mutant cancers to PI3K inhibitors. We report the activity of the P+T in solid tumors with PI3K pathway activation, along with the PD biomarker analysis. Methods: We previously reported the dose escalation phase identifying 125mg P given 3-weeks-on, 1-week-off in combination with T 2mg as the recommended phase 2 dose (R2PD, Lim, ASCO 2017). We report the results in solid tumors with confirmed activating mutations (mts) in the PI3K pathway, from dose escalation and expansion, with no prior exposure to CDK4/6 or PI3K pathway inhibitors. PD studies include analyses of platelet-rich plasma (PRP) and paired tumour biopsies. Results: 20 pts (median age 61, range 34-72) were treated at the doublet RP2D, M/F 7/13, with a median 4 prior treatments (range 2-11). Tumour types included colorectal, breast, lung, endometrial,oligodendroglioma and head and neck cancers. Durable disease control occurred in 3 patients with ER+ advanced breast cancer with responses lasting &gt;6 months including 1 pt with a H1047R PIK3CAmt with an ongoing RECIST PR&gt;36 cycles, 2 pts with PIK3CAmt colorectal cancer had RECIST SD for &gt;5 months, and 1 patient with a PIK3CGmt anaplastic oligodendroglioma had clinical and radiological benefit lasting 5.5 months. Treatment was well tolerated with predictable G1-2 adverse events (AEs). G3 toxicities of neutropenia (n=6), thrombocytopenia (2), rash (2), mucositis (1) and raised transaminases (1 each) were all transient with no G4/5 AEs. Significant decreases in tumour pRb, and pAKT and pGSK3ß in PRP, confirmed modulation of both CDK4/6 and PI3K pathways at R2PD. Conclusions: Doublet P+T is well tolerated at the combination RP2D, with PD evidence of PI3K and CDK4/6 modulation in both plasma and tumor. Promising preliminary anti-tumor activity is seen in a mixed histology cohort selected for activating PIK3 mutations. Clinical trial information: NCT02389842.

AstragalosideIV inhibits the invasion and metastasis of SiHa cervical cancer cells via the TGF‑β1‑mediated PI3K and MAPK pathways.

Astragaloside IV is the main ingredient of the medicinal herb Radix astragali, which has reported to have antitumor activity in vitro and in vivo. To determine whether the inhibitory effect of astragaloside IV on the invasion and metastasis of the cervical cancer cells is associated with epithelial‑mesenchymal transition (EMT), wound healing and Transwell assays were performed using SiHa cervical cancer cells and demonstrated that astragaloside IV inhibited invasion and migration of human SiHa cervical cancer cells in vitro. Immunocytochemical and western blot analyses indicated that astragaloside IV inhibited EMT by affecting the expression of transforming growth factor‑β1 (TGF‑β1) and E‑cadherin in the cancer cells. Two Smad‑independent pathways mediated by TGF‑β1 were identified to be associated with the effects of astragaloside IV, namely, mitogen‑activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PI3K) signaling pathways. The data indicated that astragaloside IV has inhibitory effects on phosphorylation of P38 MAPK, PI3K, AKT and mTOR of SiHa cells of cervical cancer. Furthermore, MAPK and PI3K pathway inhibitors were administered to the cancer cells and the expression of E‑cadherin, a marker of EMT, was determined by reverse transcription‑quantitative polymerase chain reaction. The results demonstrated that MAPK and PI3K pathways were involved in the inhibitory effect of astragaloside IV on EMT. In vivo small animal imaging techniques was performed and demonstrated that astragaloside IV inhibited the metastasis of cervical cancer cells. Taken together, the findings demonstrated that astragaloside IV inhibits the invasion and migration of cervical cancer cells in vitro and in vivo.

Adiponectin and Serine/Threonine Kinase Akt Modulation by Triiodothyronine and/or LY294002 in 3T3-L1 Adipocytes.

Adipose tissue (AT), an endocrine organ that modulates several physiological functions by synthesizing and releasing adipokines such as adiponectin, is a metabolic target of triiodothyronine (T3). T3 and adiponectin play important roles in controlling normal metabolic functions such as stimulation of fatty acid oxidation and increase in thermogenesis. The phosphatidylinositol 3-kinase (PI3K) pathway is important for the differentiation of preadipocytes into adipocytes and can be activated by T3 for the transcription of specific genes, such as adiponectin. We examined the role of PI3K in adiponectin modulation by T3 action in murine adipocytes (3T3-L1). The 3T3-L1 adipocytes were treated with 1000 nM T3 for 1 h in the presence or absence of 50 μM LY294002 (LY), a PI3K inhibitor. Then, we assessed the expression of adiponectin and the phosphorylated serine/threonine kinase Akt (pAkt), a PI3K signaling protein, in the adipocytes. Adiponectin and pAKT levels were higher in the T3-adipocyte cells, whereas in the LY group adiponectin was elevated and pAKT was decreased compared to the control (C). PI3K pathway inhibition for 1 h and posterior treatment with T3, in LY + T3, reduced the adiponectin level and increased pAKT levels compared to those in LY. T3 stimulated adiponectin levels by PI3K pathway activation and T3 can compensate alteration in the PI3K pathway, because with inhibition of the pathway it is able to maintain the basal levels of adiponectin and pAKT.

Erratum: Will PI3K pathway inhibitors be effective as single agents in patients with cancer?

[This corrects the article DOI: 10.18632/oncotarget.409.].

Assessment of Functional Phosphatidylinositol 3-Kinase Pathway Activity in Cancer Tissue Using Forkhead Box-O Target Gene Expression in a Knowledge-Based Computational Model

The phosphatidylinositol 3-kinase (PI3K) pathway is commonly activated in cancer. Tumors are potentially sensitive to PI3K pathway inhibitors, but reliable diagnostic tests that assess functional PI3K activity are lacking. Because PI3K pathway activity negatively regulates forkhead box-O (FOXO) transcription factor activity, FOXO target gene expression is inversely correlated with PI3K activity. Aknowledge-based Bayesian computational model was developed to infer PI3K activity in cancer tissue samples from FOXO target gene mRNA levels and validated in cancer cell lines treated with PI3K inhibitors. However, applied to patient tissue samples, FOXO was often active in cancer types with expected active PI3K. SOD2 was differentially expressed between FOXO-active healthy and cancer tissue samples, indicating that cancer-associated cellular oxidative stress alternatively activated FOXO. To enable correct interpretation of active FOXO in cancer tissue, threshold levels for normal SOD2 expression in healthy tissue were defined above which FOXO activity is oxidative stress induced and below which PI3K regulated. In slow-growing luminal A breast cancer and low Gleason score prostate cancer, FOXO was active in a PI3K-regulated manner, indicating inactive PI3K. In aggressive luminal B, HER2, and basal breast cancer, FOXO was increasingly inactive or actively induced by oxidative stress, indicating PI3K activity. We provide a decision tree that facilitates functional PI3K pathway activity assessment in tissue samples from patients with cancer for therapy response prediction and prognosis.

Abstract 3932: Metabolic biomarkers predict the sensitivity to phosphatidylinositol 3-kinase pathway inhibitor in small-cell lung carcinoma

Abstract Comprehensive genomic analysis has revealed that the PI3K/AKT/mTOR pathway is a feasible therapeutic target in small-cell lung carcinoma (SCLC). However, biomarkers to identify patients likely to benefit from inhibitors of this pathway have not been identified. Here we show that metabolic features determine sensitivity to the PI3K/mTOR dual inhibitor gedatolisib in SCLC cells. We analyzed the phosphatidyl lipid profile including the acyl groups of 11 SCLC cell lines using electrospray ionization mass spectrometry. We found that a specific phosphatidylinositol (3,4,5)-triphosphate (PIP3) subspecies lipid product, PIP3 (38:4), is predictive in assessing sensitivity to gedatolisib. We generated a large-scale metabolomic dataset for 28 SCLC cell lines. Notably, we found that higher amounts of purine-related aqueous metabolites such as hypoxanthine led to resistance to PI3K pathway inhibition. The levels of the mRNA encoding hypoxanthine phosphoribosyl transferase 1 (HPRT1), a key component of the purine salvage pathway, differed significantly between SCLC cells sensitive or resistant to gedatolisib. Loss of HPRT1 in SCLC cells decreased cellular proliferation in the presence of gedatolisib compared with a control. Further, complementation with purine metabolites could reverse the vulnerability to targeting of the PI3K pathway in SCLC cells normally sensitive to gedatolisib. These results indicate that the mechanism of resistance to PI3K pathway inhibitors is mediated by activation of the purine salvage pathway, which supplies purine resources for nucleotide biosynthesis. Metabolic profiles of clinical samples of SCLC revealed that purine-related metabolites were higher in SCLC tumor tissues, suggesting that higher amounts of purine-related aqueous metabolites might be characteristic of SCLC biology. Metabolomics is a powerful approach for identifying novel therapeutic biomarkers applicable to SCLC treatment. Citation Format: Shigeki Umemura, Hideki Makinoshima, Genichiro Ishii, Takehiko Sasaki, Hiroyasu Esumi, Koichi Goto, Katsuya Tsuchihara. Metabolic biomarkers predict the sensitivity to phosphatidylinositol 3-kinase pathway inhibitor in small-cell lung carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3932.