The present and future of PI3K inhibitors for cancer therapy

Targeting PI3K family with small-molecule inhibitors in cancer therapy: current clinical status and future directions

The Phosphatidylinositol-3-kinase (PI3K) family is well-known to comprise three classes of intracellular enzymes. Class I PI3Ks primarily function in signaling by responding to cell surface receptor stimulation, while class II and III are more involved in membrane transport. Under normal physiological conditions, the PI3K signaling network orchestrates cell growth, division, migration and survival. Aberrant activation of the PI3K signaling pathway disrupts cellular activity and metabolism, often marking the onset of cancer. Currently, the Food and Drug Administration (FDA) has approved the clinical use of five class I PI3K inhibitors. These small-molecule inhibitors, which exhibit varying selectivity for different class I PI3K family members, are primarily used in the treatment of breast cancer and hematologic malignancies. Therefore, the development of novel class I PI3K inhibitors has been a prominent research focus in the field of oncology, aiming to enhance potential therapeutic selectivity and effectiveness. In this review, we summarize the specific structures of PI3Ks and their functional roles in cancer progression. Additionally, we critically evaluate small molecule inhibitors that target class I PI3K, with a particular focus on their clinical applications in cancer treatment. Moreover, we aim to analyze therapeutic approaches for different types of cancers marked by aberrant PI3K activation and to identify potential molecular targets amenable to intervention with small-molecule inhibitors. Ultimately, we propose future directions for the development of therapeutic strategies that optimize cancer treatment outcomes by modulating the PI3K family.

A novel iheyamine A derivative L42 suppresses acute myeloid leukemia via dual regulation of the PI3K/AKT/FOXO3a axis and TNF signaling pathway

Acute myeloid leukemia (AML) is one of the most common hematopoietic malignancies and the development of new drugs is crucial for the treatment of this lethal disease. Iheyamine A is a nonmonoterpenoid azepinoindole alkaloid from the ascidian Polycitorella sp., and its anticancer mechanism has not been investigated in leukemias. Herein, we showed the significant antileukemic activity of L42 in AML cell lines HEL, HL-60 and THP-1. The IC50 values were 0.466±0.099 µM, 0.356±0.023 µM, 0.475±0.084 µM in the HEL, HL-60 and THP-1 cell lines, respectively, which were lower than the IC50 (2.594±0.271 µM) in the normal liver cell line HL-7702. Furthermore, L42 significantly inhibited the growth of peripheral blood mononuclear cells (PBMCs) from an AML patient. In vivo, L42 effectively suppressed leukemia progression in a mouse model induced by Friend murine leukemia virus (F-MuLV). Mechanistically, we showed that L42 induced cell cycle arrest and apoptosis in leukemia cell lines. RNA sequencing analysis of L42-treated THP-1 cells revealed that the differentially expressed genes (DEGs) were enriched in the cell cycle and apoptosis and predominantly enriched in the PI3K/AKT pathway. Accordingly, L42 decreased the expression of the phospho-PI3K (p85), phospho-AKT and phospho-FOXO3a. Docking and CETSA analysis indicated that L42 bound to the PI3K isoform p110α (PIK3CA), which was implicated in the suppression of the PI3K/AKT pathway. L42 was also shown to initiate the TNF signaling-mediated apoptosis. Moreover, L42 exhibited stronger anti-leukemia activity and sensitivity in IDH2-mutant HEL cells than in IDH2-wild-type control. In conclusion, L42 effectively suppresses cell proliferation and triggers apoptosis in AML cell lines in part through inhibition of the PI3K/AKT signaling pathway to restore FOXO3a expression and activation of the TNF signaling pathway. Thus, the iheyamine A derivative L42 represents a novel candidate for AML therapy.

Cellular and molecular events in colorectal cancer: biological mechanisms, cell death pathways, drug resistance and signalling network interactions

Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide, affecting millions each year. It emerges from the colon or rectum, parts of the digestive system, and is closely linked to both genetic and environmental factors. In CRC, genetic mutations such as APC, KRAS, and TP53, along with epigenetic changes like DNA methylation and histone modifications, play crucial roles in tumor development and treatment responses. This paper delves into the complex biological underpinnings of CRC, highlighting the pivotal roles of genetic alterations, cell death pathways, and the intricate network of signaling interactions that contribute to the disease's progression. It explores the dysregulation of apoptosis, autophagy, and other cell death mechanisms, underscoring the aberrant activation of these pathways in CRC. Additionally, the paper examines how mutations in key molecular pathways, including Wnt, EGFR/MAPK, and PI3K, fuel CRC development, and how these alterations can serve as both diagnostic and prognostic markers. The dual function of autophagy in CRC, acting as a tumor suppressor or promoter depending on the context, is also scrutinized. Through a comprehensive analysis of cellular and molecular events, this research aims to deepen our understanding of CRC and pave the way for more effective diagnostics, prognostics, and therapeutic strategies.

Capivasertib in Hormone Receptor-Positive, Human Epidermal Growth Factor Receptor 2-Negative advanced breast cancer

PURPOSE

This review discusses the role and efficacy of Capivasertib in managing Hormone Receptor-Positive (HR+) breast cancer.

SUMMARY

Breast cancer is the most prevalent type of cancer among women worldwide. This article is an in-depth analysis of advanced therapeutic options involving Capivasertib in treating HR+ Breast Cancer. It focuses on the mode of action, efficacy, clinical trials, and comparison with fulvestrant alone. This review also highlights the therapy's precision in targeting specific cancer cells. Its mechanism of action involves preventing cancer cells from growing and having a cytotoxic effect on them. It improves progression-free survival while maintaining the quality of life. The side effects can be easily managed by dose reduction or discontinuation of the drug. This article sheds light on the ongoing trials and FDA recognition.

CONCLUSION

In conclusion, Capivasertib-fulvestrant therapy shows potential as an innovative therapeutic option for HR+ breast cancer but warrants additional research, especially in randomized control trials (RCT). It resulted in longer progression-free survival compared to fulvestrant alone. Its side effect profile is minimal.

Resistance to Targeted Inhibitors of the PI3K/AKT/mTOR Pathway in Advanced Oestrogen-Receptor-Positive Breast Cancer

The PI3K/AKT/mTOR signalling pathway is one of the most frequently activated pathways in breast cancer and also plays a central role in the regulation of several physiologic functions. There are major efforts ongoing to exploit precision medicine by developing inhibitors that target the three kinases (PI3K, AKT, and mTOR). Although multiple compounds have been developed, at present, there are just three inhibitors approved to target this pathway in patients with advanced ER-positive, HER2-negative breast cancer: everolimus (mTOR inhibitor), alpelisib (PIK3CA inhibitor), and capivasertib (AKT inhibitor). Like most targeted cancer drugs, resistance poses a major problem in the clinical setting and is a factor that has frequently limited the overall efficacy of these agents. Drug resistance can be categorised into intrinsic or acquired resistance depending on the timeframe it has developed within. Whereas intrinsic resistance exists prior to a specific treatment, acquired resistance is induced by a therapy. The majority of patients with ER-positive, HER2-negative advanced breast cancer will likely be offered an inhibitor of the PI3K/AKT/mTOR pathway at some point in their cancer journey, with the options available depending on the approval criteria in place and the cancer's mutation status. Within this large cohort of patients, it is likely that most will develop resistance at some point, which makes this an area of interest and an unmet need at present. Herein, we review the common mechanisms of resistance to agents that target the PI3K/AKT/mTOR signalling pathway, elaborate on current management approaches, and discuss ongoing clinical trials attempting to mitigate this significant issue. We highlight the need for additional studies into AKT1 inhibitor resistance in particular.

Gedatolisib shows superior potency and efficacy versus single-node PI3K/AKT/mTOR inhibitors in breast cancer models

The PI3K, AKT, and mTOR (PAM) pathway is frequently dysregulated in breast cancer (BC) to accommodate high catabolic and anabolic activities driving tumor growth. Current therapeutic options for patients with hormone receptor (HR) + / HER2- advanced BC (ABC) include PAM inhibitors that selectively inhibit only one PAM pathway node, which can lead to drug resistance as cells rapidly adapt to maintain viability. We hypothesized that gedatolisib, which potently inhibits all Class I PI3K isoforms, as well as mTORC1 and mTORC2, may be more effective in BC cells than single-node PAM inhibitors by limiting adaptive resistances. By using multiple functional assays, a panel of BC cell lines was evaluated for their sensitivity to four different PAM inhibitors: gedatolisib (pan-PI3K/mTOR inhibitor), alpelisib (PI3Kα inhibitor), capivasertib (AKT inhibitor), and everolimus (mTORC1 inhibitor). Gedatolisib exhibited more potent and efficacious anti-proliferative and cytotoxic effects regardless of the PAM pathway mutational status of the cell lines compared to the single-node PAM inhibitors. The higher efficacy of gedatolisib was confirmed in three-dimensional culture and in BC PDX models. Mechanistically, gedatolisib decreased cell survival, DNA replication, cell migration and invasion, protein synthesis, glucose consumption, lactate production, and oxygen consumption more effectively than the other PAM inhibitors tested. These results indicate that inhibition of multiple PAM pathway nodes by a pan-PI3K/mTOR inhibitor like gedatolisib may be more effective at inducing anti-tumor activity than single-node PAM inhibitors. A global Phase 3 study is currently evaluating gedatolisib plus fulvestrant with and without palbociclib in patients with HR+/HER2- ABC.

Ilicicolin C suppresses the progression of prostate cancer by inhibiting PI3K/AKT/mTOR pathway

Aberrant activation of the PI3K/AKT pathway is a driving factor in the development of prostate cancer. Therefore, inhibiting the function of the PI3K/AKT signaling pathway is a strategy for the treatment of prostate cancer. Ilicicolin C is an ascochlorin derivative isolated from the coral-derived fungus Acremonium sclerotigenum GXIMD 02501. Which has anti-inflammatory activity, but its activity against prostate cancer has not yet been elucidated. MTT assay, plate clone-formation assay, flow cytometry and real-time cell analysis technology were used to detect the effects of ilicicolin C on cell viability, proliferation, apoptosis and migration of prostate cancer cells. Molecular docking software and surface plasmon resonance technology were used to analyze the interaction between ilicicolin C and PI3K/AKT proteins. Western blot assay was performed to examine the changes in protein expression. Finally, QikProp software was used to simulate the process of ilicicolin C in vivo, and a zebrafish xenograft model was used to further verify the anti-prostate cancer activity of ilicicolin C in vivo. Ilicicolin C showed cytotoxic effects on prostate cancer cells, with the most significant effect on PC-3 cells. Ilicicolin C inhibited proliferation and migration of PC-3 cells. It could also block the cell cycle and induce apoptosis in PC-3 cells. In addition, ilicicolin C could bind to PI3K/AKT proteins. Furthermore, ilicicolin C inhibited the expression of PI3K, AKT and mTOR proteins and could also regulate the expression of downstream proteins in the PI3K/AKT/mTOR signaling pathway. Moreover, the calculations speculated that ilicicolin C was well absorbed orally, and the zebrafish xenograft model confirmed the in vivo anti-prostate cancer effect of ilicicolin C. Ilicicolin C emerges as a promising marine compound capable of inducing apoptosis of prostate cancer cells by counteracting the aberrant activation of PI3K/AKT/mTOR, suggesting that ilicicolin C may be a viable candidate for anti-prostate cancer drug development. These findings highlight the potential of ilicicolin C against prostate cancer and shed light on its mechanism of action.

Pyrazolopyridine-based kinase inhibitors for anti-cancer targeted therapy

The need for effective cancer treatments continues to be a challenge for the biomedical research community. In this case, the advent of targeted therapy has significantly improved therapeutic outcomes. Drug discovery and development efforts targeting kinases have resulted in the approval of several small-molecule anti-cancer drugs based on ATP-mimicking heterocyclic cores. Pyrazolopyridines are a group of privileged heterocyclic cores in kinase drug discovery, which are present in several inhibitors that have been developed against various cancers. Notably, selpercatinib, glumetinib, camonsertib and olverembatinib have either received approval or are in late-phase clinical studies. This review presents the success stories employing pyrazolopyridine scaffolds as hinge-binding cores to address various challenges in kinase-targeted drug discovery research.

PI3K/AKT Signaling Pathway Mediated Autophagy in Oral Carcinoma - A Comprehensive Review

Oral cancer is the most heterogeneous cancer at clinical and histological levels. PI3K/AKT/mTOR pathway was identified as one of the most commonly modulated signals in oral cancer, which regulates major cellular and metabolic activity of the cell. Thus, various proteins of PI3K/AKT/mTOR pathway were used as therapeutic targets for oral cancer, to design more specific drugs with less off-target toxicity. This review sheds light on the regulation of PI3K/AKT/mTOR, and its role in controlling autophagy and associated apoptosis during the progression and metastasis of oral squamous type of malignancy (OSCC). In addition, we reviewed in detail the upstream activators and the downstream effectors of PI3K/AKT/mTOR signaling as potential therapeutic targets for oral cancer treatment.

Microarray-based detection and expression analysis of drug resistance in an animal model of peritoneal metastasis from colon cancer

Chemotherapy drugs efficiently eradicate rapidly dividing differentiated cells by inducing cell death, but poorly target slowly dividing cells, including cancer stem cells and dormant cancer cells, in the later course of treatment. Prolonged exposure to chemotherapy results in a decrease in the proportion of apoptotic cells in the tumour mass. To investigate and characterize the molecular basis of this phenomenon, microarray-based expression analysis was performed to compare tHcred2-DEVD-EGFP-caspase 3-sensor transfected C-26 tumour cells that were harvested after engraftment into mice treated with or without 5-FU. Peritoneal metastasis was induced by intraperitoneal injection of C-26 cells, which were subsequently reisolated from omental metastatic tumours after the mice were sacrificed by the end of the 10th day after tumour injection. The purity of reisolated tHcred2-DEVD-EGFP-caspase 3-sensor-expressing C-26 cells was confirmed using FLIM, and total RNA was extracted for gene expression profiling. The validation of relative transcript levels was carried out via real-time semiquantitative RT‒PCR assays. Our results demonstrated that chemotherapy induced the differential expression of mediators of cancer cell dormancy and cell survival-related genes and downregulation of both intrinsic and extrinsic apoptotic signalling pathways. Despite the fact that some differentially expressed genes, such as BMP7 and Prss11, have not been thoroughly studied in the context of chemoresistance thus far, they might be potential candidates for future studies on overcoming drug resistance.

Optimal targeting of PI3K-AKT and mTOR in advanced oestrogen receptor-positive breast cancer

The growing availability of targeted therapies for patients with advanced oestrogen receptor-positive breast cancer has improved survival, but there remains much to learn about the optimal management of these patients. The PI3K-AKT and mTOR pathways are among the most commonly activated pathways in breast cancer, whose crucial role in the pathogenesis of this tumour type has spurred major efforts to target this pathway at specific kinase hubs. Approvals for oestrogen receptor-positive advanced breast cancer include the PI3K inhibitor alpelisib for PIK3CA-mutated tumours, the AKT inhibitor capivasertib for tumours with alterations in PIK3CA, AKT1, or PTEN, and the mTOR inhibitor everolimus, which is used irrespective of mutation status. The availability of different inhibitors leaves physicians with a potentially challenging decision over which of these therapies should be used for individual patients and when. In this Review, we present a comprehensive summary of our current understanding of the pathways and the three inhibitors and discuss strategies for the optimal sequencing of therapies in the clinic, particularly after progression on a CDK4/6 inhibitor.

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.

A novel pan-PI3K inhibitor KTC1101 synergizes with anti-PD-1 therapy by targeting tumor suppression and immune activation

BACKGROUND

Phosphoinositide 3-kinases (PI3Ks) are critical regulators of diverse cellular functions and have emerged as promising targets in cancer therapy. Despite significant progress, existing PI3K inhibitors encounter various challenges such as suboptimal bioavailability, potential off-target effects, restricted therapeutic indices, and cancer-acquired resistance. Hence, novel inhibitors that overcome some of these challenges are needed. Here, we describe the characterization of KTC1101, a novel pan-PI3K inhibitor that simultaneously targets tumor cell proliferation and the tumor microenvironment. Our studies demonstrate that KTC1101 significantly increases the anti-PD-1 efficacy in multiple pre-clinical mouse models.

METHODS

KTC1101 was synthesized and characterized employing chemical synthesis, molecular modeling, Nuclear Magnetic Resonance (NMR), and mass spectrometry. Its target specificity was confirmed through the kinase assay, JFCR39 COMPARE analysis, and RNA-Seq analysis. Metabolic stability was verified via liver microsome and plasma assays, pharmacokinetics determined by LC-MS/MS, and safety profile established through acute toxicity assays to determine the LD50. The antiproliferative effects of KTC1101 were evaluated in a panel of cancer cell lines and further validated in diverse BALB/c nude mouse xenograft, NSG mouse xenograft and syngeneic mouse models. The KTC1101 treatment effect on the immune response was assessed through comprehensive RNA-Seq, flow cytometry, and immunohistochemistry, with molecular pathways investigated via Western blot, ELISA, and qRT-PCR.

RESULTS

KTC1101 demonstrated strong inhibition of cancer cell growth in vitro and significantly impeded tumor progression in vivo. It effectively modulated the Tumor Microenvironment (TME), characterized by increased infiltration of CD8+ T cells and innate immune cells. An intermittent dosing regimen of KTC1101 enhanced these effects. Notably, KTC1101 synergized with anti-PD-1 therapy, significantly boosting antitumor immunity and extending survival in preclinical models.

CONCLUSION

KTC1101's dual mechanism of action-directly inhibiting tumor cell growth and dynamically enhancing the immune response- represents a significant advancement in cancer treatment strategies. These findings support incorporating KTC1101 into future oncologic regimens to improve the efficacy of immunotherapy combinations.

Strategies and techniques for preclinical therapeutic targeting of PI3K in oncology: where do we stand in 2024?

INTRODUCTION

The PI3K/AKT/mTOR signaling pathway is an important signaling pathway in eukaryotic cells that is activated in a variety of cancers and is also associated with treatment resistance. This signaling pathway is an important target for anticancer therapy and holds great promise for research. At the same time PI3K inhibitors have a general problem that they have unavoidable toxic side effects.

AREAS COVERED

This review provides an explanation of the role of PI3K in the development and progression of cancer, including several important mutations, and a table listing the cancers caused by these mutations. We discuss the current landscape of PI3K inhibitors in preclinical and clinical trials, address the mechanisms of resistance to PI3K inhibition along with their associated toxic effects, and highlight significant advancements in preclinical research of this field. Furthermore, based on our study and comprehension of PI3K, we provide a recapitulation of the key lessons learned from the research process and propose potential measures for improvement that could prove valuable.

EXPERT OPINION

The PI3K pathway is a biological pathway of great potential value. However, the reduction of its toxic side effects and combination therapies need to be further investigated.

Multiomic profiling of breast cancer cells uncovers stress MAPK-associated sensitivity to AKT degradation

More than 50% of human tumors display hyperactivation of the serine/threonine kinase AKT. Despite evidence of clinical efficacy, the therapeutic window of the current generation of AKT inhibitors could be improved. Here, we report the development of a second-generation AKT degrader, INY-05-040, which outperformed catalytic AKT inhibition with respect to cellular suppression of AKT-dependent phenotypes in breast cancer cell lines. A growth inhibition screen with 288 cancer cell lines confirmed that INY-05-040 had a substantially higher potency than our first-generation AKT degrader (INY-03-041), with both compounds outperforming catalytic AKT inhibition by GDC-0068. Using multiomic profiling and causal network integration in breast cancer cells, we demonstrated that the enhanced efficacy of INY-05-040 was associated with sustained suppression of AKT signaling, which was followed by induction of the stress mitogen-activated protein kinase (MAPK) c-Jun N-terminal kinase (JNK). Further integration of growth inhibition assays with publicly available transcriptomic, proteomic, and reverse phase protein array (RPPA) measurements established low basal JNK signaling as a biomarker for breast cancer sensitivity to AKT degradation. Together, our study presents a framework for mapping the network-wide signaling effects of therapeutically relevant compounds and identifies INY-05-040 as a potent pharmacological suppressor of AKT signaling.

Tumor location matters, next generation sequencing mutation profiling of left-sided, rectal, and right-sided colorectal tumors in 552 patients

Despite the introduction of new molecular classifications, advanced colorectal cancer (CRC) is treated with chemotherapy supplemented with anti-EGFR and anti-VEGF targeted therapy. In this study, 552 CRC cases with different primary tumor locations (250 left side, 190 rectum, and 112 right side) were retrospectively analyzed by next generation sequencing for mutations in 50 genes. The most frequently mutated genes were TP53 in left-sided tumors compared to right-sided tumors and BRAF in right-sided tumors compared to left-sided tumors. Mutations in KRAS, NRAS, and BRAF were not detected in 45% of patients with left-sided tumors and in 28.6% of patients with right-sided tumors. Liver metastases were more common in patients with left-sided tumors. Tumors on the right side were larger at diagnosis and had a higher grade (G3) than tumors on the left. Rectal tumors exhibit distinctive biological characteristics when compared to left-sided tumors, including a higher absence rate of KRAS, NRAS, and BRAF mutations (47.4% in rectal versus 42.8% in left-sided tumors). These rectal tumors are also unique in their primary metastasis site, which is predominantly the lungs, and they have varying mutation rates, particularly in genes such as BRAF, FBXW7, and TP53, that distinguish them from tumors found in other locations. Primary tumor location has implications for the potential treatment of CRC with anti-EGFR therapy.

Synergistic Anti-Cancer Effects of ERB-041 and Genistein through Estrogen Receptor Suppression-Mediated PI3K/AKT Pathway Downregulation in Canine Mammary Gland Tumor Cells

Canine-mammary-gland tumors (CMTs) are prevalent in female dogs, with approximately 50% of them being malignant and often presenting as inoperable owing to their size or metastasis. Owing to poor outcomes, effective alternatives to conventional chemotherapy for humans are necessary. Two estrogen receptors, estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which act in opposition to each other, are involved, and CMT growth involves ERα through the phosphoinositide 3-kinases (PI3K)/AKT pathway. In this study, we aimed to identify the synergistic anti-cancer effects of ERB-041, an ERβ agonist, and genistein, an isoflavonoid from soybeans known to have ERβ-specific pseudo-estrogenic actions, on CMT-U27 and CF41.Mg CMT cell lines. ERB-041 and genistein synergistically inhibited cell proliferation and increased the number of annexin V-positive cells in both cell lines. Furthermore, we observed a synergistic increase in the Bax/Bcl-2 ratio and cleaved caspase-3 expression. Additionally, cell-cycle arrest occurred through the synergistic regulation of cyclin D1 and cyclin-dependent kinase 4 (CDK4). We also found a synergistic decrease in the expression of ERα, and the expression of proteins involved in the PI3K/AKT pathway, including p-PI3K, phosphatase and tensin homolog (PTEN), AKT, and mechanistic target of rapamycin (mTOR). In conclusion, ERB-041 and genistein exhibited a synergistic anticancer effect on CMTs, suggesting that cotreatment with ERB-041 and genistein is a promising treatment for CMTs.

Molecular Targeting of the Phosphoinositide-3-Protein Kinase (PI3K) Pathway across Various Cancers

The dysregulation of the phosphatidylinositol-3-kinase (PI3K) pathway can lead to uncontrolled cellular growth and tumorigenesis. Targeting PI3K and its downstream substrates has been shown to be effective in preclinical studies and phase III trials with the approval of several PI3K pathway inhibitors by the Food and Drug Administration (FDA) over the past decade. However, the limited clinical efficacy of these inhibitors, intolerable toxicities, and acquired resistances limit the clinical application of PI3K inhibitors. This review discusses the PI3K signaling pathway, alterations in the PI3K pathway causing carcinogenesis, current and novel PI3K pathway inhibitors, adverse effects, resistance mechanisms, challenging issues, and future directions of PI3K pathway inhibitors.

β1 integrin mediates unresponsiveness to PI3Kα inhibition for radiochemosensitization of 3D HNSCC models

Phosphoinositide 3-kinase (PI3K)-α represents a key intracellular signal transducer involved in the regulation of key cell functions such as cell survival and proliferation. Excessive activation of PI3Kα is considered one of the major determinants of cancer therapy resistance. Despite preclinical and clinical evaluation of PI3Kα inhibitors in various tumor entities, including head and neck squamous cell carcinoma (HNSCC), it remains elusive how conventional radiochemotherapy can be enhanced by concurrent PI3K inhibitors and how PI3K deactivation mechanistically exerts its effects. Here, we investigated the radiochemosensitizing potential and adaptation mechanisms of four PI3K inhibitors, Alpelisib, Copanlisib, AZD8186, and Idelalisib in eight HNSCC models grown under physiological, three-dimensional matrix conditions. We demonstrate that Alpelisib, Copanlisib and AZD8186 but not Idelalisib enhance radio- and radiochemosensitivity in the majority of HNSCC cell models (= responders) in a manner independent of PIK3CA mutation status. However, Alpelisib promotes MAPK signaling in non-responders compared to responders without profound impact on Akt, NFκB, TGFβ, JAK/STAT signaling and DNA repair. Bioinformatic analyses identified unique gene mutations associated with extracellular matrix to be more frequent in non-responder cell models than in responders. Finally, we demonstrate that targeting of the cell adhesion molecule β1 integrin on top of Alpelisib sensitizes non-responders to radiochemotherapy. Taken together, our study demonstrates the sensitizing potential of Alpelisib and other PI3K inhibitors in HNSCC models and uncovers a novel β1 integrin-dependent mechanism that may prove useful in overcoming resistance to PI3K inhibitors.

A comprehensive review of small molecules targeting PI3K pathway: Exploring the structural development for the treatment of breast cancer

Cancer stands as one of the deadliest diseases, ranking second in terms of its global impact. Despite the presence of numerous compelling theories concerning its origins, none have succeeded in fully elucidating the intricate nature of this ailment. Among the prevailing concerns in today's world, breast cancer proliferation remains a significant issue, particularly affecting females. The abnormal proliferation of the PI3K pathway emerges as a prominent driver of breast cancer, underscoring its role in cellular survival and proliferation. Consequently, targeting this pathway has emerged as a leading strategy in breast cancer therapeutics. Within this context, the present article explores the current landscape of anti-tumour drug development, focusing on structural activity relationships (SAR) in PI3K targeting breast cancer treatment. Notably, certain moieties like triazines, pyrimidine, quinazoline, quinoline, and pyridoxine have been explored as potential PI3K inhibitors for combating breast cancer. Various heterocyclic small molecules are undergoing clinical trials, such as Alpelisib, the first orally available FDA-approved drug targeting PI3K; others include buparlisib, pictilisib, and taselisib, which inhibit class I PI3K. These drugs are used for the treatment of breast cancer but still have various side effects with their high cost. Therefore, the primary goal of this review is to include all current advances in the development of anticancer medicines that target PI3K over-activation in the treatment of breast cancer.

Revolutionizing cancer care strategies: immunotherapy, gene therapy, and molecular targeted therapy

Despite the availability of technological advances in traditional anti-cancer therapies, there is a need for more precise and targeted cancer treatment strategies. The wide-ranging shortfalls of conventional anticancer therapies such as systematic toxicity, compromised life quality, and limited to severe side effects are major areas of concern of conventional cancer treatment approaches. Owing to the expansion of knowledge and technological advancements in the field of cancer biology, more innovative and safe anti-cancerous approaches such as immune therapy, gene therapy and targeted therapy are rapidly evolving with the aim to address the limitations of conventional therapies. The concept of immunotherapy began with the capability of coley toxins to stimulate toll-like receptors of immune cells to provoke an immune response against cancers. With an in-depth understating of the molecular mechanisms of carcinogenesis and their relationship to disease prognosis, molecular targeted therapy approaches, that inhibit or stimulate specific cancer-promoting or cancer-inhibitory molecules respectively, have offered promising outcomes. In this review, we evaluate the achievement and challenges of these technically advanced therapies with the aim of presenting the overall progress and perspective of each approach.

Rational design and optimization of novel 4-methyl quinazoline derivatives as PI3K/HDAC dual inhibitors with benzamide as zinc binding moiety for the treatment of acute myeloid leukemia

Simultaneous inhibition of PI3K and HDAC has shown promise for treating various cancers, leading to discovery and development of their dual inhibitors as novel anticancer agents. Herein, we disclose a new series of PI3K/HDAC dual inhibitors bearing a benzamide moiety as the pharmacophore of HDAC inhibition. Based on systematic structure-activity relationship study, compounds 36 and 51 featuring an alkyl and benzoyl linker respectively were identified with favorable potencies against both PI3K and HDAC. In cellular assays, compounds 36 and 51 showed significantly enhanced antiproliferative activities against various cancer cell lines relative to single-target inhibitors. Furthermore, western blotting analysis shows compounds 36 and 51 suppressed AKT phosphorylation and increased H3 acetylation in MV4-11 cells, while flow cytometry analysis reveals both compounds dose-dependently induced cell cycle arrest and cell apoptosis. Supported by pharmacokinetic studies, compounds 36 and 51 were subjected to the in vivo evaluation in a MV4-11 xenograft model, demonstrating significant and dose-dependent anticancer efficacies. Overall, this work provides a promising approach for the treatment of AML by simultaneously inhibiting PI3K and HDAC with a dual inhibitor.

Discovery, Optimization, and Evaluation of Potent and Selective DNA-PK Inhibitors in Combination with Chemotherapy or Radiotherapy for the Treatment of Malignancies

Given the multifaceted biological functions of DNA-PK encompassing DNA repair pathways and beyond, coupled with the susceptibility of DNA-PK-deficient cells to DNA-damaging agents, significant strides have been made in the pursuit of clinical potential for DNA-PK inhibitors as synergistic adjuncts to chemo- or radiotherapy. Nevertheless, although substantial progress has been made with the discovery of potent inhibitors of DNA-PK, the clinical trial landscape requires even more potent and selective molecules. This necessitates further endeavors to expand the repertoire of clinically accessible DNA-PK inhibitors for the ultimate benefit of patients. Described herein are the obstacles that were encountered and the solutions that were found, which eventually led to the identification of compound 31t. This compound exhibited a remarkable combination of robust potency and exceptional selectivity along with favorable in vivo profiles as substantiated by pharmacokinetic studies in rats and pharmacodynamic assessments in H460, BT474, and A549 xenograft models.

Efficacy and Safety of Phosphatidylinositol 3-kinase Inhibitors for Patients with Breast Cancer: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Phosphatidylinositol 3-kinase (PI3K) inhibitors belong to the class of drugs that inhibit the activity of the PI3K protein, which is commonly overexpressed in breast cancer cells. However, there is a need to summarize the evidence to provide conclusive advice on the benefit of PI3K inhibitors in breast cancer patients. Therefore, this review assessed the effectiveness and safety of the PI3K inhibitors amongst breast cancer patients.

METHODS

Searches were made in PubMed Central, EMBASE, MEDLINE, SCOPUS, CENTRAL, WHO trial registry and Clinicaltrials.gov up to December 2022. Meta-analysis was executed using the random-effects model. Pooled hazard ratio (HR)/risk ratio (RR) was reported with 95% confidence intervals (CIs).

RESULTS

In total, 13 studies were included in the analysis. Most were multi-country studies and had a higher risk of bias. Regarding the efficacy parameters, pooled HR for progression-free survival was 0.79 (95%CI: 0.67-0.92), pooled RR for complete response was 1.54 [95%CI: 1.14 to 2.09], partial response was 1.18 [95%CI: 0.87-1.61], overall response was 1.20 [95%CI: 0.93-1.56], stable disease was 1.09 [95%CI: 0.78-1.53], progressive disease was 0.80 [95%CI: 0.74 to 0.87], and clinical benefit was 1.08 [95%CI: 0.80-1.49]. For safety parameters, pooled RR for hyperglycemia was 4.57 [95%CI: 3.15-6.62], and gastrointestinal toxicity was 1.82 [95%CI: 1.56 to 2.14].

CONCLUSION

PI3K inhibitors had better efficacy than the present standard of concern for patients with breast cancer, especially among patients with PIK3CA mutations. Hence, clinicians and oncologists can provide this drug for the target population with extra caution for diabetes patients.

Inhibitors of the PI3K/AKT/mTOR pathway in human malignancies; trend of current clinical trials

The phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway regulates proliferation, survival and metabolism, and its dysregulation is one of the most frequent oncogenic events across human malignancies. Over the last two decades, there has been significant focus on the clinical development of PI3K pathway inhibitors. More than 40 different inhibitors of this axis have reached various stages of clinical trials, but only a few of them have been approved by the Food and Drug Administration (FDA) for cancer treatment. These clinical results, however, could be improved given the importance of PI3K signaling in cancer and its role in linking cancer growth with metabolism. In this systematic review, after a glance at PI3K/AKT/mTOR pathway and its different inhibitors, we retrieved registered clinical trials evaluating the efficacy and safety of PI3K/AKT/mTOR inhibitors on Clinicaltrials.gov. Following the extraction of the data, finally we analyzed 2250 included studies in multiple steps, beginning with an overview and moving on to the details about type of malignancies, inhibitors, and treatment strategies. We also took a closer look at more than 100 phase III-IV clinical trials to pinpoint promising therapies, hoping that presenting a comprehensive picture of current clinical trials casts a flash of light on what remains to be done in future clinical trials of PI3K/AKT/mTOR inhibitors in human malignancies.

Design, synthesis, and biological evaluation of novel bivalent PI3K inhibitors for the potential treatment of cancer

Phosphatidylinositol 3-kinase (PI3K) signaling is among the most common alterations in cancer and has become a key target for cancer drug development. Based on a 4-methyl quinazoline scaffold, we designed and synthesized a novel series of bivalent PI3K inhibitors with different linker lengths and types. Bivalent PI3K inhibitor 27 demonstrates improved PI3K potency and antiproliferative cell activity, relative to the corresponding monovalent inhibitor 11. Compound 27 also significantly blocks the PI3K signal pathway, induces cell cycle arrest in G1 phase, and inhibits colony formation and cell migration. Furthermore, compound 27 shows dose-dependent anticancer efficacies in a HGC-27 xenograft mice model. Overall, this work provides a possible strategy to discover novel PI3K inhibitors for the treatment of cancers.

Jean DJ, Tieu T, Ladd B, Hilbert B, Wang W, Alltucker JT, Manimala S, Kryukov GV, Brooijmans N, Dowdell G, Jonsson P, Huff M, Guzman-Perez A, Jackson EL, Goncalves MD, Stuart DD. STX-478, a Mutant-Selective, Allosteric PI3Kα Inhibitor Spares Metabolic Dysfunction and Improves Therapeutic Response in PI3Kα-Mutant Xenografts

Phosphoinositide 3-kinase α (PIK3CA) is one of the most mutated genes across cancers, especially breast, gynecologic, and head and neck squamous cell carcinoma tumors. Mutations occur throughout the gene, but hotspot mutations in the helical and kinase domains predominate. The therapeutic benefit of isoform-selective PI3Kα inhibition was established with alpelisib, which displays equipotent activity against the wild-type and mutant enzyme. Inhibition of wild-type PI3Kα is associated with severe hyperglycemia and rash, which limits alpelisib use and suggests that selectively targeting mutant PI3Kα could reduce toxicity and improve efficacy. Here we describe STX-478, an allosteric PI3Kα inhibitor that selectively targets prevalent PI3Kα helical- and kinase-domain mutant tumors. STX-478 demonstrated robust efficacy in human tumor xenografts without causing the metabolic dysfunction observed with alpelisib. Combining STX-478 with fulvestrant and/or cyclin-dependent kinase 4/6 inhibitors was well tolerated and provided robust and durable tumor regression in ER+HER2- xenograft tumor models.

SIGNIFICANCE

These preclinical data demonstrate that the mutant-selective, allosteric PI3Kα inhibitor STX-478 provides robust efficacy while avoiding the metabolic dysfunction associated with the nonselective inhibitor alpelisib. Our results support the ongoing clinical evaluation of STX-478 in PI3Kα-mutated cancers, which is expected to expand the therapeutic window and mitigate counterregulatory insulin release. See related commentary by Kearney and Vasan, p. 2313. This article is featured in Selected Articles from This Issue, p. 2293.

Non-coding RNAs' function in cancer development, diagnosis and therapy

While previous research on cancer biology has focused on genes that code for proteins, in recent years it has been discovered that non-coding RNAs (ncRNAs)play key regulatory roles in cell biological functions. NcRNAs account for more than 95% of human transcripts and are an important entry point for the study of the mechanism of cancer development. An increasing number of studies have demonstrated that ncRNAs can act as tumor suppressor genes or oncogenes to regulate tumor development at the epigenetic level, transcriptional level, as well as post-transcriptional level. Because of the importance of ncRNAs in cancer, most clinical trials have focused on ncRNAs to explore whether ncRNAs can be used as new biomarkers or therapies. In this review, we focus on recent studies of ncRNAs including microRNAs (miRNAs), long ncRNAs (lncRNAs), circle RNAs (circRNAs), PIWI interacting RNAs (piRNAs), and tRNA in different types of cancer and explore the application of these ncRNAs in the development of cancer and the identification of relevant therapeutic targets and tumor biomarkers. Graphical abstract drawn by Fidraw.

Cholesterol biogenesis is a PTEN-dependent actionable node for the treatment of endocrine therapy-refractory cancers

PTEN and PIK3CA mutations are the most prevalent PI3K pathway alterations in prostate, breast, colorectal, and endometrial cancers. p110β becomes the prominent PI3K isoform upon PTEN loss. In this study, we aimed to understand the molecular mechanisms of PI3K dependence in the absence of PTEN. Using online bioinformatical tools, we examined two publicly available microarray datasets with aberrant PI3K activation. We found that the rate-limiting enzyme of cholesterol biogenesis, SQLE, was significantly upregulated in p110β-hyperactivated or PTEN-deficient mouse prostate tumors. Concomitantly, the expression of cholesterol biosynthesis pathway enzymes was directly correlated with PI3K activation status in microarray datasets and diminished upon PTEN re-expression in PTEN-null prostate cancer cells. Particularly, PTEN re-expression decreased SQLE protein levels in PTEN-deficient prostate cancer cells. We performed targeted metabolomics and detected reduced levels of cholesteryl esters as well as free cholesterol upon PTEN re-expression. Notably, PTEN-null prostate and breast cancer cell lines were more sensitive to pharmacological intervention with the cholesterol pathway than PTEN-replete cancer cells. Since steroid hormones use sterols as structural precursors, we studied whether cholesterol biosynthesis may be a metabolic vulnerability that enhances antihormone therapy in PTEN-null castration-resistant prostate cancer cells. Coinhibition of cholesterol biosynthesis and the androgen receptor enhanced their sensitivity. Moreover, PTEN suppression in endocrine therapy-resistant luminal-A breast cancer cells leads to an increase in SQLE expression and a corresponding sensitization to the inhibition of cholesterol synthesis. According to our data, targeting cholesterol biosynthesis in combination with the hormone receptor signaling axis can potentially treat hormone-resistant prostate and breast cancers.

Anti-cancer effect of palmatine through inhibition of the PI3K/AKT pathway in canine mammary gland tumor CMT-U27 cells

Canine mammary gland tumors (CMTs) are the most common and lethal cancers in female dogs. Dysregulated phosphoinositide 3-kinases (PI3K)/AKT pathway reportedly was involved in the growth and metastasis of CMTs. However, there are few studies on therapeutic strategies for targeting the PI3K pathway in CMTs. In this study, we aimed to determine whether palmatine, a natural isoquinoline alkaloid with anti-cancer properties, could inhibit the growth of CMTs and whether the inhibitory effect was mediated through the PI3K/AKT pathway. Our in vitro experiments on CMT-U27, a CMT cell line, showed that palmatine reduced cell proliferation and induced cell death. Western blotting results revealed that palmatine decreased the protein expression of PI3K, PTEN, AKT, and mechanistic target of rapamycin in the PI3K/AKT pathway, which was supported by the results of immunocytochemistry. Additionally, palmatine suppressed the migration and tube formation of canine aortic endothelial cells as well as the migration of CMT U27 cells. Our in vivo results showed that palmatine inhibited tumor growth in a CMT-U27 mouse xenograft model. We observed a decreased expression of proteins in the PI3K/AKT pathway in tumor tissues, similar to the in vitro results. Furthermore, palmatine significantly disrupted the tumor vasculature and inhibited metastasis to adjacent lymph nodes. In conclusion, our findings demonstrate that palmatine exerts anti-cancer effects against CMTs by inhibiting PI3K/AKT signaling pathway, suggesting that palmatine has potential as a canine-specific PI3K inhibitor for the treatment of CMTs.

NF-κB signaling in neoplastic transition from epithelial to mesenchymal phenotype

NF-κB transcription factors are critical regulators of innate and adaptive immunity and major mediators of inflammatory signaling. The NF-κB signaling is dysregulated in a significant number of cancers and drives malignant transformation through maintenance of constitutive pro-survival signaling and downregulation of apoptosis. Overactive NF-κB signaling results in overexpression of pro-inflammatory cytokines, chemokines and/or growth factors leading to accumulation of proliferative signals together with activation of innate and select adaptive immune cells. This state of chronic inflammation is now thought to be linked to induction of malignant transformation, angiogenesis, metastasis, subversion of adaptive immunity, and therapy resistance. Moreover, accumulating evidence indicates the involvement of NF-κB signaling in induction and maintenance of invasive phenotypes linked to epithelial to mesenchymal transition (EMT) and metastasis. In this review we summarize reported links of NF-κB signaling to sequential steps of transition from epithelial to mesenchymal phenotypes. Understanding the involvement of NF-κB in EMT regulation may contribute to formulating optimized therapeutic strategies in cancer. Video Abstract.

NLRP6 potentiates PI3K/AKT signalling by promoting autophagic degradation of p85α to drive tumorigenesis

The PI3K/AKT pathway plays an essential role in tumour development. NOD-like receptors (NLRs) regulate innate immunity and are implicated in cancer, but whether they are involved in PI3K/AKT pathway regulation is poorly understood. Here, we report that NLRP6 potentiates the PI3K/AKT pathway by binding and destabilizing p85α, the regulatory subunit of PI3K. Mechanistically, NLRP6 recruits the E3 ligase RBX1 to p85α and ubiquitinates lysine 256 on p85α, which is recognized by the autophagy cargo receptor OPTN, causing selective autophagic degradation of p85α and subsequent activation of the PI3K/AKT pathway by reducing PTEN stability. We further show that loss of NLRP6 suppresses cell proliferation, colony formation, cell migration, and tumour growth in glioblastoma cells in vitro and in vivo. Disruption of the NLRP6/p85α interaction using the Pep9 peptide inhibits the PI3K/AKT pathway and generates potent antitumour effects. Collectively, our results suggest that NLRP6 promotes p85α degradation via selective autophagy to drive tumorigenesis, and the interaction between NLRP6 and p85α can be a promising therapeutic target for tumour treatment.

Immune checkpoint inhibitor- and phosphatidylinositol-3-kinase inhibitor-related diabetes induced by antineoplastic drugs: two case reports and a literature review

Immune checkpoint inhibitor (ICI)- and phosphatidylinositol-3-kinase inhibitor (PI3Ki)-related diabetes mellitus are common side effects of anti-tumor drug use that present mainly as hyperglycemia. Here, we present two case reports of diabetes mellitus caused by the use of tremelimumab and apalutamide, respectively, in cancer treatment, and a comprehensive, comparative review of the literature on these forms of diabetes. Case 1 presented with diabetic ketoacidosis and was diagnosed with ICI-related diabetes mellitus and treated with insulin. Case 2 was diagnosed with PI3Ki-related diabetes mellitus, and her blood glucose level returned to normal with the use of metformin and dapagliflozin. We systematically searched the PubMed database for articles on ICI- and PI3Ki-related diabetes mellitus and characterized the differences in clinical features and treatment between these two forms of diabetes.

Isoform-selective targeting of PI3K: time to consider new opportunities?

Phosphoinositide-3-kinases (PI3Ks) are central to several cellular signaling pathways in human physiology and are potential pharmacological targets for many pathologies including cancer, thrombosis, and pulmonary diseases. Tremendous efforts to develop isoform-selective inhibitors have culminated in the approval of several drugs, validating PI3K as a tractable and therapeutically relevant target. Although successful therapeutic validation has focused on isoform-selective class I orthosteric inhibitors, recent clinical findings have indicated challenges regarding poor drug tolerance owing to sustained on-target inhibition. Hence, additional approaches are warranted to increase the clinical benefits of specific clinical treatment options, which may involve the employment of so far underexploited targeting modalities or the development of inhibitors for currently underexplored PI3K class II isoforms. We review recent key discoveries in the development of isoform-selective inhibitors, focusing particularly on PI3K class II isoforms, and highlight the emerging importance of developing a broader arsenal of pharmacological tools.

Quatramer™ encapsulation of dual-targeted PI3-Kδ/HDAC6 inhibitor, HSB-510, suppresses growth of breast cancer

Multiple studies have shown that the progression of breast cancer depends on multiple signaling pathways, suggesting that therapies with multitargeted anticancer agents will offer improved therapeutic benefits through synergistic effects in inhibiting cancer growth. Dual-targeted inhibitors of phosphoinositide 3-kinase (PI3-K) and histone deacetylase (HDAC) have emerged as promising cancer therapy candidates. However, poor aqueous solubility and bioavailability limited their efficacy in cancer. The present study investigates the encapsulation of a PI3-Kδ/HDAC6 dual inhibitor into hybrid block copolymers (polylactic acid-methoxy polyethylene glycol; polylactic acid-polyethylene glycol-polypropylene glycol-polyethylene glycol-polylactic acid) (HSB-510) as a delivery system to target PI3-Kδ and HDAC6 pathways in breast cancer cells. The prepared HSB-510 showed an average diameter of 96 ± 3 nm, a zeta potential of -17 ± 2 mV, and PDI of ˂0.1 with a slow and sustained release profile of PI3-Kδ/HDAC6 inhibitors in a nonphysiological buffer. In vitro studies with HSB-510 have demonstrated substantial growth inhibition of breast cancer cell lines, MDA-MB-468, SUM-149, MCF-7, and Ehrlich ascites carcinoma (EAC) as well as downregulation of phospho-AKT, phospho-ERK, and c-Myc levels. Importantly, bi-weekly treatment of Balb/c wild-type mice harboring EAC cells with HSB-510 at a dose of 25 mg/kg resulted in significant tumor growth inhibition. The treatment with HSB-510 was without any significant effect on the body weights of the mice. These results demonstrate that a novel Quatramer encapsulation of a PI3-Kδ/HDAC6 dual inhibitor (HSB-510) represents an approach for the successful targeting of breast cancer and potentially other cancer types.

PI3K/AKT/mTOR signaling transduction pathway and targeted therapies in cancer

The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved signal transduction network in eukaryotic cells that promotes cell survival, cell growth, and cell cycle progression. Growth factor signalling to transcription factors in the PAM axis is highly regulated by multiple cross-interactions with several other signaling pathways, and dysregulation of signal transduction can predispose to cancer development. The PAM axis is the most frequently activated signaling pathway in human cancer and is often implicated in resistance to anticancer therapies. Dysfunction of components of this pathway such as hyperactivity of PI3K, loss of function of PTEN, and gain-of-function of AKT, are notorious drivers of treatment resistance and disease progression in cancer. In this review we highlight the major dysregulations in the PAM signaling pathway in cancer, and discuss the results of PI3K, AKT and mTOR inhibitors as monotherapy and in co-administation with other antineoplastic agents in clinical trials as a strategy for overcoming treatment resistance. Finally, the major mechanisms of resistance to PAM signaling targeted therapies, including PAM signaling in immunology and immunotherapies are also discussed.

New insights into molecular signaling pathways and current advancements in prostate cancer diagnostics & therapeutics

Prostate adenocarcinoma accounts for more than 20% of deaths among males due to cancer. It is the fifth-leading cancer diagnosed in males across the globe. The mortality rate is quite high due to prostate cancer. Despite the fact that advancements in diagnostics and therapeutics have been made, there is a lack of effective drugs. Metabolic pathways are altered due to the triggering of androgen receptor (AR) signaling pathways, and elevated levels of dihydrotestosterone are produced due to defects in AR signaling that accelerate the growth of prostate cancer cells. Further, PI3K/AKT/mTOR pathways interact with AR signaling pathway and act as precursors to promote prostate cancer. Prostate cancer therapy has been classified into luminal A, luminal B, and basal subtypes. Therapeutic drugs inhibiting dihydrotestosterone and PI3K have shown to give promising results to combat prostate cancer. Many second-generation Androgen receptor signaling antagonists are given either as single agent or with the combination of other drugs. In order to develop a cure for metastasized prostate cancer cells, Androgen deprivation therapy (ADT) is applied by using surgical or chemical methods. In many cases, Prostatectomy or local radiotherapy are used to control metastasized prostate cancer. However, it has been observed that after 1.5 years to 2 years of Prostatectomy or castration, there is reoccurrence of prostate cancer and high incidence of castration resistant prostate cancer is seen in population undergone ADT. It has been observed that Androgen derivation therapy combined with drugs like abiraterone acetate or docetaxel improve overall survival rate in metastatic hormone sensitive prostate cancer (mHSPC) patients. Scientific investigations have revealed that drugs inhibiting poly ADP Ribose polymerase (PARP) are showing promising results in clinical trials in the prostate cancer population with mCRPC and DNA repair abnormalities. Recently, RISUG adv (reversible inhibition of sperm under guidance) has shown significant results against prostate cancer cell lines and MTT assay has validated substantial effects of this drug against PC3 cell lines. Current review paper highlights the advancements in prostate cancer therapeutics and new drug molecules against prostate cancer. It will provide detailed insights on the signaling pathways which need to be targeted to combat metastasized prostate cancer and castration resistant prostate cancer.

Emerging Therapies for Breast Cancer

The steady, incremental improvements in outcomes for both early-stage and advanced breast cancer patients are, in large part, attributable to the success of novel systemic therapies. In this review, we discuss key conceptual paradigms that have underpinned this success including (1) targeting the driver: the identification and targeting of major oncoproteins in breast cancers; (2) targeting the lineage pathway: inhibition of those pathways that drive normal mammary epithelial cell proliferation that retain importance in cancer; (3) targeting precisely: the application of molecular classifiers to refine therapy selection for specific cancers, and of antibody-drug conjugates to pinpoint tumor and tumor promoting cells for eradication; and (4) exploiting synthetic lethality: leveraging unique vulnerabilities that cancer-specific molecular alterations induce. We describe promising examples of novel therapies that have been discovered within each of these paradigms and suggest how future drug development efforts might benefit from the continued application of these principles.

Loss of CDKN2A/B is a Molecular Marker of High-grade Histology and is Associated with Aggressive Behavior in Acinic Cell Carcinoma

Acinic cell carcinoma (AciCC) is a rare salivary gland cancer with excellent prognosis in most cases. However, a subset of patients will develop distant metastasis and die of disease. Recently, a 2-tiered grading scheme in AciCC was proposed to recognize patients at risk of poor outcome. We performed a genetic analysis of AciCC to explore the underlying molecular correlates of the tumor grade and examined programmed death ligand 1 (PD-L1) expression to identify potential candidates for immunotherapy. A retrospective cohort of 55 patients included 34 high-grade (HG) and 21 low-grade AciCCs. Forty-three cases were subjected to targeted exome sequencing by Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets. PD-L1 immunohistochemistry was performed in 33 cases. Tumor mutation burden was low with a median of 1 and 2 mutations in low-grade and HG AciCCs, respectively. CDKN2A/B was the most frequently altered gene, and loss-of-function mutations were found only in HG but not in low-grade AciCCs (18/31 [58.1%] vs 0/12 [0%], P < .001). CDKN2A/B alterations were significantly associated with distant metastasis, which occurred in 16/18 (88.9%) CDKN2A/B mutants versus 11/25 (44%) wild-type cases (P = .004, Fisher exact test). Sequential profiling of multiple temporally distant samples from the same patient demonstrated intratumor heterogeneity, including the detection of CDKN2A/B deletion in the second, in HG metastasis only. ATM and PTEN mutations were detected in 6/31 (19.4%) and 5/31 (16.1%); ARID2, BIRC3, and FBXW7 mutations each in 4/31 (12.9%); and TP53, MTAP, and FAT1 each in 3/31 (9.7%) HG AciCC. PD-L1-positive labeling was more common in HG AciCC (9/17, 52.9% vs 3/16, 18.9%, P = .071). CDKN2A/B mutations in AciCC represent a molecular marker of HG histology and disease progression, providing a rationale for further studies to determine their prognostic and therapeutic significance in this salivary gland cancer. AciCC with ATM mutations may be amenable to targeted therapy. Immunotherapy can be considered to be a treatment option for a subset of patients with AciCC.

Alpinumisoflavone Activates Disruption of Calcium Homeostasis, Mitochondria and Autophagosome to Suppress Development of Endometriosis

Alpinumisoflavone is an isoflavonoid extracted from the Cudrania tricuspidate fruit and Genista pichisermolliana. It has various physiological functions, such as anti-inflammation, anti-proliferation, and apoptosis, in malignant tumors. However, the effect of alpinumisoflavone is still not known in chronic diseases and other benign reproductive diseases, such as endometriosis. In this study, we examined the cell death effects of alpinumisoflavone on the endometriosis cell lines, End1/E6E7 and VK2/E6E7. Results indicated that alpinumisoflavone inhibited cell migration and proliferation and led to cell cycle arrest, depolarization of mitochondria membrane potential, apoptosis, and disruption of calcium homeostasis in the endometriosis cell lines. However, the cellular proliferation of normal uterine epithelial cells was not changed by alpinumisoflavone. The alteration in Ca²⁺ levels was estimated in fluo-4 AM-stained End1/E6E7 and VK2/E6E7 cells after alpinumisoflavone treatment with or without calcium inhibitor, 2-aminoethoxydiphenyl borate (2-APB). The results indicated that a combination of alpinumisoflavone and a calcium inhibitor reduced the calcium accumulation in the cytosol of endometriosis cells. Additionally, alpinumisoflavone decreased oxidative phosphorylation (OXPHOS) in the endometriotic cells. Moreover, protein expression analysis revealed that alpinumisoflavone inactivated AKT signaling pathways, whereas it increased MAPK, ER stress, and autophagy regulatory proteins in End1/E6E7 and VK2/E6E7 cell lines. In summary, our results suggested that alpinumisoflavone could be a promising effective management agent or an adjuvant therapy for benign disease endometriosis.

Phosphoinositide and redox dysregulation by the anticancer methylthioadenosine phosphorylase transition state inhibitor

Methylthio-DADMe-immucillin-A (MTDIA) is an 86 picomolar inhibitor of 5'-methylthioadenosine phosphorylase (MTAP) with potent and specific anti-cancer efficacy. MTAP salvages S-adenosylmethionine (SAM) from 5'-methylthioadenosine (MTA), a toxic metabolite produced during polyamine biosynthesis. Changes in MTAP expression are implicated in cancer growth and development, making MTAP an appealing target for anti-cancer therapeutics. Since SAM is involved in lipid metabolism, we hypothesised that MTDIA alters the lipidomes of MTDIA-treated cells. To identify these effects, we analysed the lipid profiles of MTDIA-treated Saccharomyces cerevisiae using ultra-high resolution accurate mass spectrometry (UHRAMS). MTAP inhibition by MTDIA, and knockout of the Meu1 gene that encodes for MTAP in yeast, caused global lipidomic changes and differential abundance of lipids involved in cell signaling. The phosphoinositide kinase/phosphatase signaling network was specifically impaired upon MTDIA treatment, and was independently validated and further characterised via altered localization of proteins integral to this network. Functional consequences of dysregulated lipid metabolism included a decrease in reactive oxygen species (ROS) levels induced by MTDIA that was contemporaneous with changes in immunological response factors (nitric oxide, tumour necrosis factor-alpha and interleukin-10) in mammalian cells. These results indicate that lipid homeostasis alterations and concomitant downstream effects may be associated with MTDIA mechanistic efficacy.

Interactions of Na+/taurocholate cotransporting polypeptide with host cellular proteins upon hepatitis B and D virus infection: novel potential targets for antiviral therapy

Na⁺/taurocholate cotransporting polypeptide (NTCP) is a member of the solute carrier (SLC) family 10 transporters (gene symbol SLC10A1) and is responsible for the sodium-dependent uptake of bile salts across the basolateral membrane of hepatocytes. In addition to its primary transporter function, NTCP is the high-affinity hepatic receptor for hepatitis B (HBV) and hepatitis D (HDV) viruses and, therefore, is a prerequisite for HBV/HDV virus entry into hepatocytes. The inhibition of HBV/HDV binding to NTCP and internalization of the virus/NTCP receptor complex has become a major concept in the development of new antiviral drugs called HBV/HDV entry inhibitors. Hence, NTCP has emerged as a promising target for therapeutic interventions against HBV/HDV infections in the last decade. In this review, recent findings on protein-protein interactions (PPIs) between NTCP and cofactors relevant for entry of the virus/NTCP receptor complex are summarized. In addition, strategies aiming to block PPIs with NTCP to dampen virus tropism and HBV/HDV infection rates are discussed. Finally, this article suggests novel directions for future investigations evaluating the functional contribution of NTCP-mediated PPIs in the development and progression of HBV/HDV infection and subsequent chronic liver disorders.

YBX1 integration of oncogenic PI3K/mTOR signalling regulates the fitness of malignant epithelial cells

In heterogeneous head and neck cancer (HNC), subtype-specific treatment regimens are currently missing. An integrated analysis of patient HNC subtypes using single-cell sequencing and proteome profiles reveals an epithelial-mesenchymal transition (EMT) signature within the epithelial cancer-cell population. The EMT signature coincides with PI3K/mTOR inactivation in the mesenchymal subtype. Conversely, the signature is suppressed in epithelial cells of the basal subtype which exhibits hyperactive PI3K/mTOR signalling. We further identify YBX1 phosphorylation, downstream of the PI3K/mTOR pathway, restraining basal-like cancer cell proliferation. In contrast, YBX1 acts as a safeguard against the proliferation-to-invasion switch in mesenchymal-like epithelial cancer cells, and its loss accentuates partial-EMT and in vivo invasion. Interestingly, phospho-YBX1 that is mutually exclusive to partial-EMT, emerges as a prognostic marker for overall patient outcomes. These findings create a unique opportunity to sensitise mesenchymal cancer cells to PI3K/mTOR inhibitors by shifting them towards a basal-like subtype as a promising therapeutic approach against HNC.

Genetic Heterogeneity and Tissue-specific Patterns of Tumors with Multiple PIK3CA Mutations

PURPOSE

To comprehensively characterize tissue-specific and molecular subclasses of multiple PIK3CA (multi-PIK3CA) mutations and assess their impact on potential therapeutic outcomes.

EXPERIMENTAL DESIGN

We profiled a pan-cancer cohort comprised of 352,392 samples across 66 tumor types using a targeted hybrid capture-based next-generation sequencing panel covering at least 324 cancer-related genes. Molecularly defined subgroups, allelic configuration, clonality, and mutational signatures were identified and tested for association with PI3K inhibitor therapeutic response.

RESULTS

Multi-PIK3CA mutations are found in 11% of all PIK3CA-mutant tumors, including 9% of low tumor mutational burden (TMB) PIK3CA-mutant tumors, and are enriched in breast and gynecologic cancers. Multi-PIK3CA mutations are frequently clonal and in cis on the same allele and occur at characteristic positions across tumor types. These mutations tend to be mutually exclusive of mutations in other driver genes, and of genes in the PI3K pathway. Among PIK3CA-mutant tumors with a high TMB, 18% are multi-PIK3CA mutant and often harbor an apolipoprotein B mRNA-editing enzyme, catalytic polypeptide (APOBEC) mutational signature. Despite large differences in specific allele combinations comprising multi-PIK3CA mutant tumors, especially across cancer types, patients with different classes of multi-PIK3CA mutant estrogen receptor-positive, HER2-negative breast cancers respond similarly to PI3K inhibition.

CONCLUSIONS

Our pan-tumor study provides biological insights into the genetic heterogeneity and tissue specificities of multi-PIK3CA mutations, with potential clinical utility to guide PI3K inhibition strategies.

Antitumor activity of the PI3K δ-sparing inhibitor MEN1611 in PIK3CA mutated, trastuzumab-resistant HER2 + breast cancer

PURPOSE

Dysregulation of the PI3K pathway is one of the most common events in breast cancer. Here we investigate the activity of the PI3K inhibitor MEN1611 at both molecular and phenotypic levels by dissecting and comparing its profile and efficacy in HER2 + breast cancer models with other PI3K inhibitors.

METHODS

Models with different genetic backgrounds were used to investigate the pharmacological profile of MEN1611 against other PI3K inhibitors. In vitro studies evaluated cell viability, PI3K signaling, and cell death upon treatment with MEN1611. In vivo efficacy of the compound was investigated in cell line- and patient-derived xenografts models.

RESULTS

Consistent with its biochemical selectivity, MEN1611 demonstrated lower cytotoxic activity in a p110δ-driven cellular model when compared to taselisib, and higher cytotoxic activity in the p110β-driven cellular model when compared to alpelisib. Moreover, MEN1611 selectively decreased the p110α protein levels in PIK3CA mutated breast cancer cells in a concentration- and proteasome-dependent manner. In vivo, MEN1611 monotherapy showed significant and durable antitumor activity in several trastuzumab-resistant PIK3CA-mutant HER2 + PDX models. The combination of trastuzumab and MEN1611 significantly improved the efficacy compared to single agent treatment.

CONCLUSIONS

The profile of MEN1611 and its antitumoral activity suggest an improved profile as compared to pan-inhibitors, which are limited by a less than ideal safety profile, and isoform selective molecules, which may potentially promote development of resistance mechanisms. The compelling antitumor activity in combination with trastuzumab in HER2 + trastuzumab-resistant, PIK3CA mutated breast cancer models is at the basis of the ongoing B-Precise clinical trial (NCT03767335).

Repurposing Inhibitors of Phosphoinositide 3-kinase as Adjuvant Therapeutics for Bacterial Infections

The rise in antimicrobial resistance and the decline in new antibiotics has created a great need for novel approaches to treat drug resistant bacterial infections. Increasing the burden of antimicrobial resistance, bacterial virulence factors allow for survival within the host, where they can evade host killing and antimicrobial therapy within their intracellular niches. Repurposing host directed therapeutics has great potential for adjuvants to allow for more effective bacterial killing by the host and antimicrobials. To this end, phosphoinositide 3-kinase inhibitors are FDA approved for cancer therapy, but also have potential to eliminate intracellular survival of pathogens. This review describes the PI3K pathway and its potential as an adjuvant target to treat bacterial infections more effectively.

PI5P4Kα supports prostate cancer metabolism and exposes a survival vulnerability during androgen receptor inhibition

Phosphatidylinositol (PI)regulating enzymes are frequently altered in cancer and have become a focus for drug development. Here, we explore the phosphatidylinositol-5-phosphate 4-kinases (PI5P4K), a family of lipid kinases that regulate pools of intracellular PI, and demonstrate that the PI5P4Kα isoform influences androgen receptor (AR) signaling, which supports prostate cancer (PCa) cell survival. The regulation of PI becomes increasingly important in the setting of metabolic stress adaptation of PCa during androgen deprivation (AD), as we show that AD influences PI abundance and enhances intracellular pools of PI-4,5-P2. We suggest that this PI5P4Kα-AR relationship is mitigated through mTORC1 dysregulation and show that PI5P4Kα colocalizes to the lysosome, the intracellular site of mTORC1 complex activation. Notably, this relationship becomes prominent in mouse prostate tissue following surgical castration. Finally, multiple PCa cell models demonstrate marked survival vulnerability following stable PI5P4Kα inhibition. These results nominate PI5P4Kα as a target to disrupt PCa metabolic adaptation to castrate resistance.

Recent advances of tanshinone in regulating autophagy for medicinal research

Initially described as an ancient and highly conserved catabolic biofunction, autophagy plays a significant role in disease pathogenesis and progression. As the bioactive ingredient of Salvia miltiorrhiza, tanshinone has recently shown profound effects in alleviating and treating various diseases by regulating autophagy. However, compared to the remarkable achievements in the known pharmacological effects of this traditional Chinese medicine, there is a lack of a concise and comprehensive review deciphering the mechanism by which tanshinone regulates autophagy for medicinal research. In this context, we concisely review the advances of tanshinone in regulating autophagy for medicinal research, including human cancer, the nervous system, and cardiovascular diseases. The pharmacological effects of tanshinone targeting autophagy involve the regulation of autophagy-related proteins, such as Beclin-1, LC3-II, P62, ULK1, Bax, ATG3, ATG5, ATG7, ATG9, and ATG12; the regulation of the PI3K/Akt/mTOR, MEK/ERK/mTOR, Beclin-1-related, and AMPK-related signaling pathways; the accumulation of reactive oxygen species (ROS); and the activation of AMPK. Notably, we found that tanshinone played a dual role in human cancers in an autophagic manner, which may provide a new avenue for potential clinical application. In brief, these findings on autophagic tanshinone and its derivatives provide a new clue for expediting medicinal research related to tanshinone compounds and autophagy.