A multicenter phase I trial of PX-866, an oral irreversible phosphatidylinositol 3-kinase inhibitor, in patients with advanced solid tumors

Targeting the RAS upstream and downstream signaling pathway for Cancer treatment

Cancer often involves the overactivation of RAS/RAF/MEK/ERK (MAPK) and PI3K-Akt-mTOR pathways due to mutations in genes like RAS, RAF, PTEN, and PIK3CA. Various strategies are employed to address the overactivation of these pathways, among which targeted therapy emerges as a promising approach. Directly targeting specific proteins, leads to encouraging results in cancer treatment. For instance, RTK inhibitors such as imatinib and afatinib selectively target these receptors, hindering ligand binding and reducing signaling initiation. These inhibitors have shown potent efficacy against Non-Small Cell Lung Cancer. Other inhibitors, like lonafarnib targeting Farnesyltransferase and GGTI 2418 targeting geranylgeranyl Transferase, disrupt post-translational modifications of proteins. Additionally, inhibition of proteins like SOS, SH2 domain, and Ras demonstrate promising anti-tumor activity both in vivo and in vitro. Targeting downstream components with RAF inhibitors such as vemurafenib, dabrafenib, and sorafenib, along with MEK inhibitors like trametinib and binimetinib, has shown promising outcomes in treating cancers with BRAF-V600E mutations, including myeloma, colorectal, and thyroid cancers. Furthermore, inhibitors of PI3K (e.g., apitolisib, copanlisib), AKT (e.g., ipatasertib, perifosine), and mTOR (e.g., sirolimus, temsirolimus) exhibit promising efficacy against various cancers such as Invasive Breast Cancer, Lymphoma, Neoplasms, and hematological malignancies. This review offers an overview of small molecule inhibitors targeting specific proteins within the RAS upstream and downstream signaling pathways in cancer.

Clinical and Preclinical Targeting of Oncogenic Pathways in PDAC: Targeted Therapeutic Approaches for the Deadliest Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the leading causes of cancer-related death worldwide. It is commonly diagnosed in advanced stages and therapeutic interventions are typically constrained to systemic chemotherapy, which yields only modest clinical outcomes. In this review, we examine recent developments in targeted therapy tailored to address distinct molecular pathway alteration required for PDAC. Our review delineates the principal signaling pathways and molecular mechanisms implicated in the initiation and progression of PDAC. Subsequently, we provide an overview of prevailing guidelines, ongoing investigations, and prospective research trajectories related to targeted therapeutic interventions, drawing insights from randomized clinical trials and other pertinent studies. This review focus on a comprehensive examination of preclinical and clinical data substantiating the efficacy of these therapeutic modalities, emphasizing the potential of combinatorial regimens and novel therapies to enhance the quality of life for individuals afflicted with PDAC. Lastly, the review delves into the contemporary application and ongoing research endeavors concerning targeted therapy for PDAC. This synthesis serves to bridge the molecular elucidation of PDAC with its clinical implications, the evolution of innovative therapeutic strategies, and the changing landscape of treatment approaches.

Biomimetic Synthesis and Chemical Proteomics Reveal the Mechanism of Action and Functional Targets of Phloroglucinol Meroterpenoids

Natural products perennially serve as prolific sources of drug leads and chemical probes, fueling the development of numerous therapeutics. Despite their scarcity, natural products that modulate protein function through covalent interactions with lysine residues hold immense potential to unlock new therapeutic interventions and advance our understanding of the biological processes governed by these modifications. Phloroglucinol meroterpenoids constitute one of the most expansive classes of natural products, displaying a plethora of biological activities. However, their mechanism of action and cellular targets have, until now, remained elusive. In this study, we detail the concise biomimetic synthesis, computational mechanistic insights, physicochemical attributes, kinetic parameters, molecular mechanism of action, and functional cellular targets of several phloroglucinol meroterpenoids. We harness synthetic clickable analogues of natural products to probe their disparate proteome-wide reactivity and subcellular localization through in-gel fluorescence scanning and cell imaging. By implementing sample multiplexing and a redesigned lysine-targeting probe, we streamline a quantitative activity-based protein profiling, enabling the direct mapping of global reactivity and ligandability of proteinaceous lysines in human cells. Leveraging this framework, we identify numerous lysine-meroterpenoid interactions in breast cancer cells at tractable protein sites across diverse structural and functional classes, including those historically deemed undruggable. We validate that phloroglucinol meroterpenoids perturb biochemical functions through stereoselective and site-specific modification of lysines in proteins vital for breast cancer metabolism, including lipid signaling, mitochondrial respiration, and glycolysis. These findings underscore the broad potential of phloroglucinol meroterpenoids for targeting functional lysines in the human proteome.

Silencing Glypican-1 enhances the antitumor effects of Pictilisib via downregulating PI3K/Akt/ERK signaling in chemo-resistant esophageal adenocarcinoma

Poorly differentiated esophageal adenocarcinoma (PDEAC) has a dismal prognosis. Glypican-1(GPC-1) is known to be upregulated in several cancer types in contrast to healthy tissues, rendering it as a biomarker. Nevertheless, the potential therapeutic targeting of GPC-1 has not been explored in PDEAC. There is accumulating evidence that GPC-1, via upregulation of PI3K/Akt/ERK signaling, plays a crucial role in the progression and chemoresistance in cancer. Pictilisib, a class I pan PI3K inhibitor, has shown promising antitumor results in clinical trials, however, has not gained widespread success due to acquired drug resistance. This study investigated the role of GPC-1 in chemo-resistant PDEAC and appraises the impact of targeted silencing of GPC-1 on the antitumor effects of Pictilisib in PDEAC cell lines. Immunohistochemistry assays in PDEAC tissue specimens demonstrated a pronounced intensity of staining with GPC-1. Upregulation of GPC-1 was found to be correlated with advanced stage and poor prognosis. In-vitro studies examined the influence of GPC-1 knockdown and Pictilisib, both as individual agents and in combination, on cytotoxicity, cell cycle distribution, apoptosis, and gene expression profiles. Silencing GPC-1 alone showed significantly reduced cell viability, migration, colony formation, epithelial-mesenchymal transition, and stemness in PDEAC cells. Significantly, knockdown of GPC-1 combined with low-dose Pictilisib led to enhancement of cytotoxicity, cell cycle arrest, and apoptosis in ESO-26 and OE-33 cells. In the xenograft mouse model, the combination of Pictilisib and GPC-1 knockdown exhibited synergy. These findings suggest that GPC-1 represents a promising target to augment chemosensitivity in esophageal adenocarcinoma.

Exploratory Food Effect Assessment in Patients in Early Clinical Development of Oncology Drugs

Instructions for administration with regard to food are a key aspect of how patients experience oral drugs. Through potential effects on pharmacokinetics, the food condition can influence safety and efficacy, and thereby is one of many dimensions of dose optimization. Regulatory guidance from major health authorities advocates for the early investigation of food effect (FE) in clinical development. In oncology, exploratory FE (eFE) evaluation is often incorporated into the first-in-human (FIH) studies in patients to inform food condition of later clinical studies. However, the design aspects of such exploratory assessments are generally under-reported and barely described, and yet complex, due to uniqueness of FIH study design and drug development process in oncology. Herein, we review literature of eFE assessment study design in oncology in patients, and present the Novartis experience in the design, execution, and impact of eFE in FIH oncology studies from 2014 to 2021. Based on this, we propose a roadmap for eFE assessment in early clinical drug development for oncology drugs in patients, including a framework for common study design options with a focus on study- and patient-level timing for typical scenarios. We also provide a broad spectrum of decision-making factors which should be evaluated to drive the design and implementation of eFE assessment, spanning from clinical development strategy, FIH study design, to compound-specific features.

Orellanine: From Fungal Origin to a Potential Future Cancer Treatment

Fungal metabolites represent an underutilized resource in the development of novel anticancer drugs. This review will focus on the promising fungal nephrotoxin orellanine, found in mushrooms including Cortinarius orellanus (Fools webcap). Emphasis will be placed on its historical significance, structural features, and associated toxicomechanics. Chromatographic methods for analysis of the compound and its metabolites, its synthesis, and chemotherapeutic potential are also discussed. Although orellanine's exceptional selectivity for proximal tubular cells is well documented, the mechanics of its toxicity in kidney tissue remains disputed. Here, the most commonly proposed hypotheses are detailed in the context of the molecule's structure, the symptoms seen following ingestion, and its characteristic prolonged latency period. Chromatographic analysis of orellanine and its related substances remains challenging, while biological evaluation of the compound is complicated by uncertainty regarding the role of active metabolites. This has limited efforts to structurally refine the molecule; despite numerous established methods for its synthesis, there is minimal published material on how orellanine's structure might be optimized for therapeutic use. Despite these obstacles, orellanine has generated promising data in preclinical studies of metastatic clear cell renal cell carcinoma, leading to the early 2022 announcement of phase I/II trials in humans.

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.

How far have we explored fungi to fight cancer?

The use of fungal cultures have been well documented in human history. Although its used in healthcare, like penicillin and statins, have saved countless of lives, but there is still no fungal products that are specifically indicated for cancers. Research into fungal-derived materials to curb cancers in the recent decades have made a considerable progress in terms of drug delivery vehicles, anticancer active ingredients and cancer immunotherapy. Various parts of the organisms have successfully been exploited to achieve specific tasks. Apart from the identification of novel anticancer compound from fungi, its native capsular structure can also be used as drug cargo to achieve higher oral bioavailability. This review summarises the anticancer potential of fungal-derived materials, highlighting the role of capsular polysaccharides, proteins, and other structures in variety of innovative utilities to fit the current pharmaceutical technology. Many bioactive compounds isolated from fungi have also been formulated into nanoparticles to achieve greater anticancer activity. The progress of fungal compounds and their analogues in clinical trials is also highlighted. In addition, the potential of various fungal species to be developed for anticancer immunotherapy are also discussed.

Targeting PI3K/AKT/mTOR Signaling Pathway in Pancreatic Cancer: From Molecular to Clinical Aspects

Although pancreatic cancer (PC) was considered in the past an orphan cancer type due to its low incidence, it may become in the future one of the leading causes of cancer death. Pancreatic ductal adenocarcinoma (PDAC) is the most frequent type of PC, being a highly aggressive malignancy and having a 5-year survival rate of less than 10%. Non-modifiable (family history, age, genetic susceptibility) and modifiable (smoking, alcohol, acute and chronic pancreatitis, diabetes mellitus, intestinal microbiota) risk factors are involved in PC pathogenesis. Chronic inflammation induced by various factors plays crucial roles in PC development from initiation to metastasis. In multiple malignant conditions such as PC, cytokines, chemokines, and growth factors activate the class I phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) (PI3K/AKT/mTOR) signaling pathway, which plays key roles in cell growth, survival, proliferation, metabolism, and motility. Currently, mTOR, AKT, and PI3K inhibitors are used in clinical studies. Moreover, PI3K/mTOR dual inhibitors are being tested in vitro and in vivo with promising results for PC patients. The main aim of this review is to present PC incidence, risk factors, tumor microenvironment development, and PI3K/AKT/mTOR dysregulation and inhibitors used in clinical, in vivo, and in vitro studies.

PI3K Inhibition for Squamous Cell Head and Neck Carcinoma

ABSTRACT

The phosphoinositide 3-kinase (PI3K) pathway is aberrantly activated in most head and neck squamous cell carcinomas, making it a prized target for targeted therapy development. Multiple PI3K inhibitors have been studied in early phase trials, with unfavorable risk-benefit ratios in molecularly unselected patient populations. Buparlisib, a potent pan-class I PI3K inhibitor, shows promising efficacy in combination with paclitaxel for advanced head and neck squamous cell carcinoma. Results of the phase III BURAN trial are awaited.

Transcriptome profiling and co-expression network analysis of lncRNAs and mRNAs in colorectal cancer by RNA sequencing

Background

Long non-coding RNAs (lncRNAs) are widely involved in the pathogenesis of cancers. However, biological roles of lncRNAs in occurrence and progression of colorectal cancer (CRC) remain unclear. The current study aimed to evaluate the expression pattern of lncRNAs and messenger RNAs (mRNAs).

Methods

RNA sequencing (RNA-Seq) in CRC tissues and adjacent normal tissues from 6 CRC patients was performed and functional lncRNA-mRNA co-expression network was constructed afterwards. Gene enrichment analysis was demonstrated using DAVID 6.8 tool. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to validate the expression pattern of differentially expressed lncRNAs. Pearson correlation analysis was applied to evaluate the relationships between selected lncRNAs and mRNAs.

Results

One thousand seven hundred and sixteenth differentially expressed mRNAs and 311 differentially expressed lncRNAs were screened out. Among these, 568 mRNAs were up-regulated while 1148 mRNAs down-regulated, similarly 125 lncRNAs were up-regulated and 186 lncRNAs down-regulated. In addition, 1448 lncRNA–mRNA co-expression pairs were screened out from 940,905 candidate lncRNA-mRNA pairs. Gene enrichment analysis revealed that these lncRNA-related mRNAs are associated with cell adhesion, collagen adhesion, cell differentiation, and mainly enriched in ECM-receptor interaction and PI3K-Akt signaling pathways. Finally, RT-qPCR results verified the expression pattern of lncRNAs, as well as the relationships between lncRNAs and mRNAs in 60 pairs of CRC tissues.

Conclusions

In conclusion, these results of the RNA-seq and bioinformatic analysis strongly suggested that the dysregulation of lncRNA is involved in the complicated process of CRC development, and providing important insight regarding the lncRNAs involved in CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09878-6.

Genomic landscape of lymphatic malformations: a case series and response to the PI3Kα inhibitor alpelisib in an N-of-1 clinical trial

Background

Lymphatic malformations (LMs) often pose treatment challenges due to a large size or a critical location that could lead to disfigurement, and there are no standardized treatment approaches for either refractory or unresectable cases.

Methods

We examined the genomic landscape of a patient cohort of LMs (n = 30 cases) that underwent comprehensive genomic profiling using a large-panel next-generation sequencing assay. Immunohistochemical analyses were completed in parallel.

Results

These LMs had low mutational burden with hotspot PIK3CA mutations (n = 20) and NRAS (n = 5) mutations being most frequent, and mutually exclusive. All LM cases with Kaposi sarcoma-like (kaposiform) histology had NRAS mutations. One index patient presented with subacute abdominal pain and was diagnosed with a large retroperitoneal LM harboring a somatic PIK3CA gain-of-function mutation (H1047R). The patient achieved a rapid and durable radiologic complete response, as defined in RECIST1.1, to the PI3Kα inhibitor alpelisib within the context of a personalized N-of-1 clinical trial (NCT03941782). In translational correlative studies, canonical PI3Kα pathway activation was confirmed by immunohistochemistry and human LM-derived lymphatic endothelial cells carrying an allele with an activating mutation at the same locus were sensitive to alpelisib treatment in vitro, which was demonstrated by a concentration-dependent drop in measurable impedance, an assessment of cell status.

Conclusions

Our findings establish that LM patients with conventional or kaposiform histology have distinct, yet targetable, driver mutations.

Funding

R.P. and W.A. are supported by awards from the Levy-Longenbaugh Fund. S.G. is supported by awards from the Hugs for Brady Foundation. This work has been funded in part by the NCI Cancer Center Support Grants (CCSG; P30) to the University of Arizona Cancer Center (CA023074), the University of New Mexico Comprehensive Cancer Center (CA118100), and the Rutgers Cancer Institute of New Jersey (CA072720). B.K.M. was supported by National Science Foundation via Graduate Research Fellowship DGE-1143953.

Clinical trial number

NCT03941782.

PI3K/Akt/mTOR Pathway and Its Role in Cancer Therapeutics: Are We Making Headway?

Cancer is a severe public health issue that is a leading cause of mortality globally. It is also an impediment to improving life expectancy worldwide. Furthermore, the global burden of cancer incidence and death is continuously growing. Current therapeutic options are insufficient for patients, and tumor complexity and heterogeneity necessitate customized medicine or targeted therapy. It is critical to identify potential cancer therapeutic targets. Aberrant activation of the PI3K/AKT/mTOR pathway has a significant role in carcinogenesis. This review summarized oncogenic PI3K/Akt/mTOR pathway alterations in cancer and various cancer hallmarks associated with the PI3K/AKT/mTOR pathway, such as cell proliferation, autophagy, apoptosis, angiogenesis, epithelial-to-mesenchymal transition (EMT), and chemoresistance. Importantly, this review provided recent advances in PI3K/AKT/mTOR inhibitor research. Overall, an in-depth understanding of the association between the PI3K/AKT/mTOR pathway and tumorigenesis and the development of therapies targeting the PI3K/AKT/mTOR pathway will help make clinical decisions.

The PI3K/Akt/mTOR axis in colorectal cancer: Oncogenic alterations, non-coding RNAs, therapeutic opportunities, and the emerging role of nanoparticles

Colorectal cancer (CRC) is one of the deadliest human malignancies worldwide. Several molecular pathways have been demonstrated to be involved in the initiation and development of CRC which among them, the overactivation of the phosphatidyl-inositol 3-kinase (PI3K)/Akt/mTOR axis is of importance. The current review aims to unravel the mechanisms by which the PI3K/Akt/mTOR pathway affects CRC progression; and also, to summarize the original data obtained from international research laboratories on the oncogenic alterations and polymorphisms affecting this pathway in CRC. Besides, we provide a special focus on the regulatory role of noncoding RNAs targeting the PI3K/Akt/mTOR pathway in this malignancy. Questions on how this axis is involved in the inhibition of apoptosis, in the induction of drug resistance, and the angiogenesis, epithelial to mesenchymal transition, and metastasis are also responded. We also discussed the PI3K/Akt pathway-associated prognostic and predictive biomarkers in CRC. In addition, we provide a general overview of PI3K/Akt/mTOR pathway inhibition whether by chemical-based drugs or by natural-based medications in the context of CRC, either as monotherapy or in combination with other therapeutic agents; however, those treatments might have life-threatening side effects and toxicities. To the best of our knowledge, the current review is one of the first ones highlighting the emerging roles of nanotechnology to overcome challenges related to CRC therapy in the hope that providing a promising platform for the treatment of CRC.

Phosphatidylinositol 3-kinase (PI3K) inhibitors: a recent update on inhibitor design and clinical trials (2016-2020)

Introduction: The phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway plays a central role in regulating cell growth and proliferation and thus has been considered as effective anticancer drug targets. Many PI3K inhibitors have been developed and progressed to various stages of clinical trials, and some have been approved as anticancer treatment. In this review, we discuss the drug design and clinical development of PI3K inhibitors over the past 4 years. We review the selectivity and potency of 47 PI3K inhibitors. Structural determinants for increasing selectivity toward PI3K subtype-selectivity or mutant selectivity are discussed. Future research direction and current clinical development in combination therapy of inhibitors involved in PI3Ks are also discussed.Area covered: This review covers clinical trial reports and patent literature on PI3K inhibitors and their selectivity published between 2016 and 2020.Expert opinion: To PI3Kα mutants (E542K, E545K, and H1047R), it is highly desirable to design and develop mutant-specific PI3K inhibitors. It is also necessary to develop subtype-selective PI3Kα inhibitors to minimize toxicity. To reduce drug resistance and to improve efficacy, future studies should include combination therapy of PI3K inhibitors with existing anticancer drugs from different pathways.

Recent insights in the PI3K/Akt pathway as a promising therapeutic target in combination with EGFR-targeting agents to treat head and neck squamous cell carcinoma

Resistance to therapies targeting the epidermal growth factor receptor (EGFR), such as cetuximab, remains a major roadblock in the search for effective therapeutic strategies in head and neck squamous cell carcinoma (HNSCC). Due to its close interaction with the EGFR pathway, redundant or compensatory activation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway has been proposed as a major driver of resistance to EGFR inhibitors. Understanding the role of each of the main proteins involved in this pathway is utterly important to develop rational combination strategies able to circumvent resistance. Therefore, the current work reviewed the role of PI3K/Akt pathway proteins, including Ras, PI3K, tumor suppressor phosphatase and tensing homolog, Akt and mammalian target of rapamycin in resistance to anti-EGFR treatment in HNSCC. In addition, we summarize PI3K/Akt pathway inhibitors that are currently under (pre)clinical investigation with focus on overcoming resistance to EGFR inhibitors. In conclusion, genomic alterations in and/or overexpression of one or more of these proteins are common in both human papillomavirus (HPV)-positive and HPV-negative HNSCC tumors. Therefore, downstream effectors of the PI3K/Akt pathway serve as promising drug targets in the search for novel therapeutic strategies that are able to overcome resistance to anti-EGFR treatment. Co-targeting EGFR and the PI3K/Akt pathway can lead to synergistic drug interactions, possibly restoring sensitivity to EGFR inhibitors and hereby improving clinical efficacy. Better understanding of the predictive value of PI3K/Akt pathway alterations is needed to allow the identification of patient populations that might benefit most from these combination strategies.

Targeting the autophagy promoted antitumor effect of T-DM1 on HER2-positive gastric cancer

Trastuzumab emtansine (T-DM1), an antibody-drug conjugate consisted of the HER2-targeted monoclonal antibody trastuzumab and the tubulin inhibitor emtansine, has shown potent therapeutic value in HER2-positive breast cancer (BC). However, a clinical trial indicated that T-DM1 exerts a limited effect on HER2-positive gastric cancer (GC), but the underlying mechanism is inconclusive. Our research attempted to reveal the probable mechanism and role of autophagy in T-DM1-treated HER2-positive GC. In this study, our results showed that T-DM1 induced apoptosis and exhibited potent therapeutic efficacy in HER2-positive GC cells. In addition, autophagosomes were observed by transmission electron microscopy. Autophagy was markedly activated and exhibited the three characterized gradations of autophagic flux, consisting of the formation of autophagosomes, the fusion of autophagosomes with lysosomes, and the deterioration of autophagosomes in autolysosomes. More importantly, autophagic inhibition by the suppressors 3-methyladenine (3-MA) and LY294002 significantly potentiated cytotoxicity and apoptosis in HER2-positive GC cells in vitro, while the combined use of LY294002 and T-DM1 elicited potent anti-GC efficacy in vivo. In mechanistic experiments, immunoblot analysis indicated the downregulated levels of Akt, mTOR, and P70S6K and confocal microscopy analysis clearly showed that autophagic inhibition promoted the fusion of T-DM1 molecules with lysosomes in GC cells. In conclusion, our research demonstrated that T-DM1 induced apoptosis as well as cytoprotective autophagy, and autophagic inhibition could potentiate the antitumor effect of T-DM1 on HER2-positive GC. Furthermore, autophagic inhibition might increase the fusion of T-DM1 with lysosomes, which might accelerate the release of the cytotoxic molecule emtansine from the T-DM1 conjugate. These findings highlight a promising therapeutic strategy that combines T-DM1 with an autophagy inhibitor to treat HER-positive GC more efficiently.

The PI3K/Akt/mTOR signaling pathway in gastric cancer; from oncogenic variations to the possibilities for pharmacologic interventions

Genetic and epigenetic alterations have been under concentrated investigations for many years in order to unearth the molecules regulating human cancer pathogenesis. However, the identification of a wide range of dysregulated genes and their protein products has raised a question regarding how the results of this large collection of alterations could converge into a formation of one malignancy. The answer may be found in the signaling cascades that regulate the survival and metabolism of the cells. Aberrancies of each participant molecule of such cascades may well result in augmented viability and unlimited proliferation of cancer cells. Among various signaling pathways, the phosphatidylinositol-3-kinase (PI3K) axis has been shown to be activated in about one-third of human cancers. One of the malignancies that is mostly affected by this axis is gastric cancer (GC), one of the most fatal cancers worldwide. In the present review, we aimed to illustrate the significance of the PI3K/Akt/mTOR axis in the pathogenesis of GC and also provided a wide perspective about the application of the inhibitors of this axis in the therapeutic strategies of this malignancy.

Androgen receptor-induced integrin α6β1 and Bnip3 promote survival and resistance to PI3K inhibitors in castration-resistant prostate cancer

The androgen receptor (AR) is the major driver of prostate cancer growth and survival. However, almost all patients relapse with castration resistant disease (CRPC) when treated with anti-androgen therapy. In CRPC, AR is often aberrantly activated independent of androgen. Targeting survival pathways downstream of AR could be a viable strategy to overcome CRPC. Surprisingly, little is known about how AR drives prostate cancer survival. Furthermore, CRPC tumors in which Pten is lost are also resistant to eradication by PI3K inhibitors. We sought to identify the mechanism by which AR drives tumor survival in CRPC to identify ways to overcome resistance to PI3K inhibition. We found that integrin α6β1 and Bnip3 are selectively elevated in CRPC downstream of AR. While integrin α6 promotes survival and is a direct transcriptional target of AR, the ability of AR to induce Bnip3 is dependent on adhesion to laminin and integrin α6β1-dependent nuclear translocation of HIF1α. Integrin α6β1 and Bnip3 were found to promote survival of CRPC cells selectively on laminin through the induction of autophagy and mitophagy. Furthermore, blocking Bnip3 or integrin α6β1 restored sensitivity to PI3K inhibitors in Pten-negative CRPC. We identified an AR driven pathway that cooperates with laminin and hypoxia to drive resistance to PI3K inhibitors. These findings can help explain in part why PI3K inhibitors have failed in clinical trials to overcome AR-dependent CRPC.

PI3K inhibitors: review and new strategies

The search is on for effective specific inhibitors for PI3Kα mutants. PI3Kα, a critical lipid kinase, has two subunits, catalytic and inhibitory. PIK3CA, the gene that encodes the p110α catalytic subunit is a highly mutated protein in cancer. Dysregulation of PI3Kα signalling is commonly associated with tumorigenesis and drug resistance. Despite its vast importance, only recently the FDA approved the first drug (alpelisib by Novartis) for breast cancer. A second (GDC0077), classified as PI3Kα isoform-specific, is undergoing clinical trials. Not surprisingly, these ATP-competitive drugs commonly elicit severe concentration-dependent side effects. Here we briefly review PI3Kα mutations, focus on PI3K drug repertoire and propose new, to-date unexplored PI3Kα therapeutic strategies. These include (1) an allosteric and orthosteric inhibitor combination and (2) taking advantage of allosteric rescue mutations to guide drug discovery.

The Impact of Whole Genome Data on Therapeutic Decision-Making in Metastatic Prostate Cancer: A Retrospective Analysis

BACKGROUND

While critical insights have been gained from evaluating the genomic landscape of metastatic prostate cancer, utilizing this information to inform personalized treatment is in its infancy. We performed a retrospective pilot study to assess the current impact of precision medicine for locally advanced and metastatic prostate adenocarcinoma and evaluate how genomic data could be harnessed to individualize treatment.

METHODS

Deep whole genome-sequencing was performed on 16 tumour-blood pairs from 13 prostate cancer patients; whole genome optical mapping was performed in a subset of 9 patients to further identify large structural variants. Tumour samples were derived from prostate, lymph nodes, bone and brain.

RESULTS

Most samples had acquired genomic alterations in multiple therapeutically relevant pathways, including DNA damage response (11/13 cases), PI3K (7/13), MAPK (10/13) and Wnt (9/13). Five patients had somatic copy number losses in genes that may indicate sensitivity to immunotherapy (LRP1B, CDK12, MLH1) and one patient had germline and somatic BRCA2 alterations.

CONCLUSIONS

Most cases, whether primary or metastatic, harboured therapeutically relevant alterations, including those associated with PARP inhibitor sensitivity, immunotherapy sensitivity and resistance to androgen pathway targeting agents. The observed intra-patient heterogeneity and presence of genomic alterations in multiple growth pathways in individual cases suggests that a precision medicine model in prostate cancer needs to simultaneously incorporate multiple pathway-targeting agents. Our whole genome approach allowed for structural variant assessment in addition to the ability to rapidly reassess an individual's molecular landscape as knowledge of relevant biomarkers evolve. This retrospective oncological assessment highlights the genomic complexity of prostate cancer and the potential impact of assessing genomic data for an individual at any stage of the disease.

Potential therapies for residual hepatoblastoma following incomplete ablation treatment in a nude mouse subcutaneous xenograft model based on lncRNA and mRNA expression profiles

Tumor recurrence following radiofrequency ablation (RFA) treatment in liver cancer is an important factor affecting patient prognosis. Furthermore, the biological role of long non‑coding RNAs (lncRNAs) in residual hepatoblastoma (HB) tissues after RFA remains largely unknown. By using microarray technology, this study investigated the expression of lncRNAs and mRNAs among four pairs of HB tissues (incomplete ablation treatment and no treatment) in a nude mouse subcutaneous xenograft model. Subsequently, bioinformatics analysis was used to understand the functions and pathways of the identified mRNAs. Finally, a connectivity map (CMap) analysis was conducted to identify potential therapeutic strategies for residual HB tissues. Compared with the untreated nude mouse subcutaneous xenograft model, in the experimental group, a significant difference in the expression of 740 lncRNAs and 663 mRNAs was detected. Subsequently, bioinformatics analysis revealed that the differentially expressed mRNAs were significantly enriched in pathways associated with antigen processing, the presentation of endogenous antigens, the regulation of cellular metabolic processes, MAPK signaling and cell cycle regulation. Additionally, six compounds (valproic acid, metformin, tanespimycin, wortmannin, fulvestrant and MK‑886) were identified by CMap analysis as potential therapeutic agents for the treatment of residual HB tissues. These findings provide a novel insight into the pathogenesis of residual HB and potential therapeutic strategies for aggressive tumor recurrence following RFA treatment in patients with HB.

Intratumoral heterogeneity and loss of ARID1A expression in gastric cancer correlates with increased PD-L1 expression in Western patients

Recent whole-genome sequencing showed frequent mutations of ARID1A in gastric cancer (GC). In this study of a large independent Central European cohort, we evaluated the expression of ARID1A in whole tissue sections (WTS) of GC testing the following hypotheses: ARID1A shows intratumoral heterogeneity, and ARID1A expression and/or heterogeneity correlates with clinicopathological patient characteristics. ARID1A expression was studied by immunohistochemistry in 450 primary GCs and 143 corresponding lymph node metastases. The expression pattern was correlated with clinicopathological characteristics and patient survival. ARID1A genotype and CpG methylation status were additionally analyzed in 7 GCs with a heterogeneous "black-and-white" expression pattern. ARID1A was expressed heterogeneously in 23 (5.1%) GCs, depicting a black-and-white pattern of negative and positive tumor areas. Complete loss of expression was found in 43 (9.6%) GCs. ARID1A status correlated significantly with tumor type according to Laurén, Epstein-Barr virus status, microsatellite instability, PD-L1 status, and nodal spread. There was no correlation with patient survival. In 4 cases with heterogeneous ARID1A expression, frame shift variants were detected. Summing up, heterogeneous or complete loss of ARID1A expression occurred in 14.7% of GCs and correlated with PD-L1 status, indicating potential for future combined anti-PD-L1/ARID1A therapy. In a subgroup of cases, ARID1A loss was heterogeneous, which suggests that ARID1A mutations might be a later event in gastric carcinogenesis.

Significance of BRAF Kinase Inhibitors for Melanoma Treatment: From Bench to Bedside

According to clinical trials, BRAF kinase inhibitors in combination with MEK kinase inhibitors are among the most promising chemotherapy regimens for the treatment of advanced BRAF-mutant melanoma, though the rate of BRAF mutation gene-bearing cutaneous melanoma is limited, especially in the Asian population. In addition, drug resistance sometimes abrogates the persistent efficacy of combined therapy with BRAF and MEK inhibitors. Therefore, recent pre-clinical study-based clinical trials have attempted to identify optimal drugs (e.g., immune checkpoint inhibitors or histone deacetylase (HDAC) inhibitors) that improve the anti-melanoma effects of BRAF and MEK inhibitors. In addition, the development of novel protocols to avoid resistance of BRAF inhibitors is another purpose of recent pre-clinical and early clinical trials. This review focuses on pre-clinical studies and early to phase III clinical trials to discuss the development of combined therapy based on BRAF inhibitors for BRAF-mutant advanced melanoma, as well as mechanisms of resistance to BRAF inhibitors.

Dual Inhibitors-Loaded Nanotherapeutics that Target Kinase Signaling Pathways Synergize with Immune Checkpoint Inhibitor

Introduction

Immune checkpoint inhibitors that boost cytotoxic T cell-based immune responses have emerged as one of the most promising approaches in cancer treatment. However, it is increasingly being realized that T cell activation needs to be rationally combined with molecularly targeted therapeutics for a maximal anti-tumor outcome. Currently, two oncogenic drivers, MAPK and PI3K-mTOR have emerged as the two main molecular targets for combining with immunotherapy. However, there are major challenges in enabling such combinations: first, such combinations can result in high rates of toxicity. Second, while, these molecular targets could be driving tumor progression, they are essential for activation of the immune cells. So, the kinase inhibitors and immunotherapy can antagonize each other.

Objectives

We rationalized that the synergistic combination of kinase inhibitors and immunotherapy could be enabled by dual inhibitors-loaded supramolecular nanotherapeutics (DiLN) that can co-deliver PI3K- and MAPK-inhibitors to the cancer cells and activate immune response by T cell-modulating immunotherapy, resulting in greater anti-tumor efficacy while minimizing toxicity.

Methods

We engineered DiLNs by designing the amphiphilic building blocks (both drugs and co-lipids) that enables supramolecular nanoassembly. DiLNs were tested for their physiochemical properties including size, morphology, stability and drug release kinetics profiles. The efficacy of DiLNs was tested in drug-resistant cells such as BRAF^V600E melanoma (D4M), Clear cell ovarian carcinoma (TOV21G) cells. The tumor inhibition efficiency of DiLNs in combination with immune checkpoint inhibitor antibody was studied in syngeneic D4M animal model.

Results

DiLNs were stable for over a month and released the drugs in a sustained manner. In vitro cytotoxicity studies in D4M and TOV21G cells showed that DiLNs were significantly more effective than free drugs. In vivo studies showed that the combination of DiLNs with anti PD-L1 antibody resulted in superior antitumor effect and survival.

Conclusion

This study shows that the rational combination of DiLNs that target multiple oncogenic signaling pathways with immune checkpoint inhibitors could emerge as an effective strategy to improve immunotherapeutic response against drug resistant tumors.

Everolimus in hormone receptor-positive metastatic breast cancer: PIK3CA mutation H1047R was a potential efficacy biomarker in a retrospective study

Background

Everolimus, an inhibitor of mammalian target of rapamycin (mTOR), has been shown to increase the efficacy of endocrine therapies in hormone receptor (HR)-positive metastatic breast cancer. However, because breast cancer is a highly heterogeneous disease, the responses of different patients to everolimus may vary. Therefore, we performed this study to better select patients who will benefit most from or be resistant to everolimus.

Methods

Patients with HR-positive breast cancer who were treated with everolimus at the Cancer Hospital, Chinese Academy of Medical Sciences from February 2014 to March 2017 were enrolled in the present study. Mutations in ctDNA were assayed in 1021 tumor-related genes via gene panel target capture-based next-generation sequencing.

Results

In total, 120 patients with metastatic breast cancer who were treated with everolimus were enrolled in the present study. The median progression-free survival (PFS) of all patients was 5.1 months (95% confidence interval [CI] 3.9–6.3 months). No difference in survival was observed between patients who received endocrine drugs used in previous treatment regimens and patients who did not receive these drugs (median PFS 5.2 and 5.1 months, respectively, p > 0.05). Additionally, we did not find any difference in outcomes between patients who had primary resistance to previously used endocrine drugs and patients who had nonprimary resistance to previous treatments (p > 0.05). Multivariate analysis showed that < 3 metastatic sites, < 2 lines of previous endocrine therapy, < 2 lines of previous chemotherapy, and treatment with everolimus combined with fulvestrant were associated with improved survival (p < 0.05). Sixteen patients underwent ctDNA analysis before everolimus treatment. The frequency of PIK3CA gene mutations was 62.5%, and H1047R was the most frequently detected mutation. Patients with the PIK3CA/H1047R mutation had longer PFS than patients with wild-type or other mutant forms of PIK3CA, and the median PFS in these two groups of patients was 8.8 and 4.1 months, respectively (p < 0.05).

Conclusions

Our data suggest that patients who receive more lines of chemotherapy or endocrine therapy are less likely to benefit from everolimus. For everolimus combination therapy, we can even select endocrine drugs that gave rise to primary resistance in previous treatments. Additionally, the PIK3CA/H1047R mutation may be a potential biomarker of sensitivity to everolimus.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5668-3) contains supplementary material, which is available to authorized users.

Identification of targets for prostate cancer immunotherapy

BACKGROUND

We performed profiling of the immune microenvironment of castration-resistant (CRPC) and castration-sensitive (CSPC) prostate cancer (PC) in order to identify novel targets for immunotherapy.

METHODS

PD-L1 and CD3/CD8 immunohistochemistry, PD-L1/2 fluorescent in situ hybridization, tumor mutation burden, microsatellite instability, and RNA-seq of 395 immune-related genes were performed in 19 CRPC and CSPC. Targeted genomic sequencing and fusion analysis were performed in 17 of these specimens.

RESULTS

CD276, PVR, and NECTIN2 were highly expressed in PC. Comparison of CRPC versus CSPC and primary versus metastatic tissue revealed the differential expression of immunostimulatory, immunosuppressive, and epithelial-to-mesenchymal transition (EMT)-related genes. Unsupervised clustering of differentially expressed genes yielded two final clusters best segregated by CRPC and CSPC status.

CONCLUSION

CD276 and the alternative checkpoint inhibition PVR/NECTIN2/CD226/TIGIT pathway emerged as relevant to PC checkpoint inhibition target development.

A Phase II Study of PX-866 in Patients With Recurrent or Metastatic Castration-resistant Prostate Cancer: Canadian Cancer Trials Group Study IND205

BACKGROUND

In PTEN-loss models, the phosphatidylinositol 3-kinase (PI3K)/AKT and androgen receptor signaling pathways cross-regulate by reciprocal feedback whereby inhibition of one activates the other, creating a rationale for co-targeting. We studied the irreversible, pan-isoform inhibitor of Class I PI-3K PX-866 singly (part A) and with abiraterone acetate (AA) in patients on AA with rising prostate-specific antigen (PSA) (part B).

PATIENTS AND METHODS

The primary endpoint was lack of progression at 12 weeks. Exploratory endpoints included changes in circulating tumor cells (CTC), pharmacodynamic studies on platelets (part A), and archival tumor exploration of PTEN as predictor of response (part B).

RESULTS

A total of 43 and 25 patients accrued to parts A and B, respectively. In part A, 14 (33%) patients were progression-free at 12 weeks, with 2 partial objective responses and 1 confirmed PSA response. Favorable CTC conversion (< 5 CTC/7.5 mL) occurred in 6 (24%) of 25 evaluable patients. In part B, 11 of 25 patients had measurable disease. Six (24%) patients were progression-free at 12 weeks. No objective or PSA responses were observed. For all 68 patients, the most common toxicities were diarrhea (53 patients), nausea (36), anorexia (24), fatigue (22), and vomiting (20). Among 17 patients for whom PTEN testing was possible, 3 had PTEN homozygous deletion and 14 had no change. No correlation between PTEN status and response was seen.

CONCLUSIONS

PX-866 had modest single agent activity. Adding AA to PX-866 showed no evidence of resistance reversal. Strategies to combine PI3K inhibition with androgen receptor-targeted therapies could consider initiation earlier, combination with other agents, and/or recruiting a selected population.

Phosphatidyl inositol 3-kinase (PI3K)-mTOR inhibitor PKI-402 inhibits breast cancer induced osteolysis

Bone metastasis causes bone pain and pathological bone fracture in breast cancer patients with a serious complication. Previous studies have demonstrated that a novel phosphatidyl inositol 3-kinase (PI3K)-mTOR inhibitor PKI-402 suppressed the growth of breast cancer cells. However, the role of PKI-402 involved in osteolysis induced by breast cancer remains unclear. In this study, we showed that treatment of PKI-402 led to significant decreases in RANKL-induced osteoclastogenesis and osteoclast-specific gene expression in mouse bone marrow-derived macrophages and reduced proliferation, migration and invasion of MDA-MB-231 breast cancer cells by blocking the PI3K-AKT-mTOR signaling pathway. Importantly, as evidenced by the observation that the administration of PKI-402 inhibited MDA-MB-231-induced osteolysis in vivo, PKI-402 exerted an inhibitory effect on osteoclast formation and bone resorption, critical for cancer cells-induced bone destruction. These results strongly suggest that PKI-402 might have a therapeutic potential to inhibit breast cancer induced osteolysis.

BRAF kinase inhibitors for treatment of melanoma: developments from early-stage animal studies to Phase II clinical trials

INTRODUCTION

Approximately, 30.4-66.0% of cutaneous melanomas possess a mutation in the BRAF gene that activates downstream signaling through the mitogen-activated protein (MAP) kinase pathway; this provides an attractive target for the treatment of advanced melanoma. Although BRAF inhibitors rapidly suppress melanoma growth, median progression-free survival remains unsatisfactory. Recent clinical trials have investigated drugs that can optimally enhance and prolong the anti-melanoma effects of BRAF inhibitors.

AREAS COVERED

This review discusses the development of BRAF inhibitor-based combination therapies for BRAF-mutant advanced melanoma.

EXPERT OPINION

Future strategies for the treatment of advanced melanoma include novel combination therapies using BRAF/MEK inhibitors and immune checkpoints inhibitors or histone deacetylase inhibitors. These combination therapies might enhance antitumor responses against melanoma, prolonging survival in advanced melanoma patients. Further clinical studies are needed to optimize these novel combination therapies.

Therapeutic Potency of PI3K Pharmacological Inhibitors of Gastrointestinal Cancer

Therapeutic targeting of phosphatidyl-inositol 3-kinase (PI3K) is considered as a possible strategy in several types of cancer, including gastrointestinal ones. In vitro and in vivo studies indicated the significance of proapoptotic and antiproliferative inhibition of PI3K. Although there are many phase 1 and 2 clinical trials on PI3K inhibitors in patients with gastrointestinal cancer, the molecular mechanism of PI3K targeting PI3K/ mTOR pathway is not clear. Panclass I, isoformselective, and dual PI3K/mTOR inhibitors are under investigation. This review aimed to indicate PI3K-dependent targeting mechanisms in gastrointestinal cancer and the evaluation of related clinical data.

Altered cancer metabolism in mechanisms of immunotherapy resistance

Many metabolic alterations, including the Warburg effect, occur in cancer cells that influence the tumor microenvironment, including switching to glycolysis from oxidative phosphorylation, using opportunistic modes of nutrient acquisition, and increasing lipid biosynthesis. The altered metabolic landscape of the tumor microenvironment can suppress the infiltration of immune cells and other functions of antitumor immunity through the production of immune-suppressive metabolites. Metabolic dysregulation in cancer cells further affects the expression of cell surface markers, which interferes with immune surveillance. Immune checkpoint therapies have revolutionized the standard of care for some patients with cancer, but disease in many others is resistant to immunotherapy. Specific metabolic pathways involved in immunotherapy resistance include PI3K-Akt-mTOR, hypoxia-inducible factor (HIF), adenosine, JAK/STAT, and Wnt/Beta-catenin. Depletion of essential amino acids such as glutamine and tryptophan and production of metabolites like kynurenine in the tumor microenvironment also blunt immune cell function. Targeted therapies against metabolic checkpoints could work in synergy with immune checkpoint therapy. This combined strategy could be refined by profiling patients' mutation status before treatment and identifying the optimal sequencing of therapies. This personalized combinatorial approach, which has yet to be explored, may well pave the way for overcoming resistance to immunotherapy.

Cross Talk Networks of Mammalian Target of Rapamycin Signaling With the Ubiquitin Proteasome System and Their Clinical Implications in Multiple Myeloma

Multiple myeloma (MM) is the second most common hematological malignancy and results from the clonal amplification of plasma cells. Despite recent advances in treatment, MM remains incurable with a median survival time of only 5-6years, thus necessitating further insights into MM biology and exploitation of novel therapeutic approaches. Both the ubiquitin proteasome system (UPS) and the PI3K/Akt/mTOR signaling pathways have been implicated in the pathogenesis, and treatment of MM and different lines of evidence suggest a close cross talk between these central cell-regulatory signaling networks. In this review, we outline the interplay between the UPS and mTOR pathways and discuss their implications for the pathophysiology and therapy of MM.

A phase I, open-label, two-stage study to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of the oral AKT inhibitor GSK2141795 in patients with solid tumors

Background We sought to determine the recommended phase II dose (RP2D) and schedule of GSK2141795, an oral pan-AKT kinase inhibitor. Patients and Methods Patients with solid tumors were enrolled in the dose-escalation phase. Pharmacokinetic (PK) analysis after a single dose (Cycle 0) informed dose escalation using accelerated dose titration. Once one grade 2 toxicity or dose-limiting toxicity was observed in Cycle 1, the accelerated dose titration was terminated and a 3 + 3 dose escalation was started. Continuous daily dosing was evaluated along with two intermittent regimens (7 days on/7 days off and 3 times per week). In the expansion phase at RP2D, patients with endometrial or prostate cancer, as well as those with select tumor types with a PIK3CA mutation, AKT mutation or PTEN loss, were enrolled. Patients were evaluated for adverse events (AEs), PK parameters, blood glucose and insulin levels, and tumor response. Results The RP2D of GSK2141795 for once-daily dosing is 75 mg. The most common (>10%) treatment-related AEs included diarrhea, fatigue, vomiting, and decreased appetite. Most AEs were low grade. The frequency of hyperglycemia increased with dose; however, at the RP2D, grade 3 hyperglycemia was only reported in 4% of patients and no grade 4 events were observed. PK characteristics were favorable, with a prolonged half-life and low peak-to-trough ratio. There were two partial responses at the RP2D in patients with either a PIK3CA mutation or PTEN loss. Conclusion GSK2141795 was safe and well-tolerated, with clinical activity seen as monotherapy at the RP2D of 75 mg daily. NCT00920257.

Phase I Trial of a Tablet Formulation of Pilaralisib, a Pan-Class I PI3K Inhibitor, in Patients with Advanced Solid Tumors

Lessons Learned.

A phase I study of the pan‐class I phosphoinositide 3‐kinase inhibitor pilaralisib (in capsule formulation) in advanced solid tumors established the maximum tolerated dose as 600 mg once daily.

The current study investigated pilaralisib in tablet formulation.

Pilaralisib tablets were associated with a favorable safety profile and preliminary antitumor activity.

Based on pharmacokinetic data, the recommended phase II dose of pilaralisib tablets was established as 400 mg once daily.

Background.

A phase I trial of pilaralisib, an oral pan‐class I phosphoinositide 3‐kinase (PI3K) inhibitor, established the maximum tolerated dose (MTD) of the capsule formulation in patients with advanced solid tumors as 600 mg once daily. This phase I study investigated pilaralisib in tablet formulation.

Materials and Methods.

Patients with advanced solid tumors received pilaralisib tablets (100–600 mg once daily). Primary endpoints were MTD and safety; secondary and exploratory endpoints included pharmacokinetics (PK), pharmacodynamics, and efficacy.

Results.

Twenty‐two patients were enrolled. No dose‐limiting toxicities (DLTs) were reported. The most common treatment‐related adverse events were diarrhea (40.9%), fatigue (40.9%), decreased appetite (22.7%), and hyperglycemia (22.7%). Pilaralisib plasma exposure did not appear to increase dose‐proportionally. Steady‐state exposure was higher with pilaralisib tablet formulation at 400 mg than with pilaralisib capsule formulation at 400 or 600 mg (mean area under the curve [AUC_0–24] 2,820,000 ng × h/mL vs. 2,653,000 and 1,930,000 ng × h/mL, respectively). Of 18 evaluable patients, 2 (11.1%) had a partial response (PR).

Conclusion.

Pilaralisib tablets were associated with a favorable safety profile and preliminary antitumor activity. MTD was not determined. The recommended phase II dose for pilaralisib tablets, based on PK data, was 400 mg once daily.

Targeting the PI3K pathway in cancer: are we making headway?

The PI3K-AKT-mTOR pathway is one of the most frequently dysregulated pathways in cancer and, consequently, more than 40 compounds that target key components of this signalling network have been tested in clinical trials involving patients with a range of different cancers. The clinical development of many of these agents, however, has not advanced to late-phase randomized trials, and the antitumour activity of those that have been evaluated in comparative prospective studies has typically been limited, or toxicities were found to be prohibitive. Nevertheless, the mTOR inhibitors temsirolimus and everolimus and the PI3K inhibitors idelalisib and copanlisib have been approved by the FDA for clinical use in the treatment of a number of different cancers. Novel compounds with greater potency and selectivity, as well as improved therapeutic indices owing to reduced risks of toxicity, are clearly required. In addition, biomarkers that are predictive of a response, such as PIK3CA mutations for inhibitors of the PI3K catalytic subunit α isoform, must be identified and analytically and clinically validated. Finally, considering that oncogenic activation of the PI3K-AKT-mTOR pathway often occurs alongside pro-tumorigenic aberrations in other signalling networks, rational combinations are also needed to optimize the effectiveness of treatment. Herein, we review the current experience with anticancer therapies that target the PI3K-AKT-mTOR pathway.

A PI3K p110α-selective inhibitor enhances the efficacy of anti-HER2/neu antibody therapy against breast cancer in mice

Combination therapies with phosphoinositide 3-kinase (PI3K) inhibitors and trastuzumab (anti-human epidermal growth factor receptor [HER]2/neu antibody) are effective against HER2+ breast cancer. Isoform-selective PI3K inhibitors elicit anti-tumor immune responses that are distinct from those induced by inhibitors of class I PI3K isoforms (pan-PI3K inhibitors). The present study investigated the therapeutic effect and potential for stimulating anti-tumor immunity of combined therapy with an anti-HER2/neu antibody and pan-PI3K inhibitor (GDC-0941) or a PI3K p110α isoform-selective inhibitor (A66) in mouse models of breast cancer. The anti-neu antibody inhibited tumor growth and enhanced anti-tumor immunity in HER2/neu+ breast cancer TUBO models, whereas GDC-0941 or A66 alone did not. Anti-neu antibody and PI3K inhibitor synergistically promoted anti-tumor immunity by increasing functional T cell production. In the presence of the anti-neu antibody, A66 was more effective than GDC-0941 at increasing the fraction of CD4⁺, CD8⁺, and IFN-γ⁺CD8⁺ T cells in the tumor-infiltrating lymphocyte population. Detection of IFN-γ levels by enzyme-linked immunospot assay showed that the numbers of tumor-specific T cells against neu and non-neu tumor antigens were increased by combined PI3K inhibitor plus anti-neu antibody treatment, with A66 exhibiting more potent effects than GDC-0941. In a TUBO (neu+) and TUBO-P2J (neu-) mixed tumor model representing immunohistochemistry 2+ tumors, A66 suppressed tumor growth and prolonged survival to a greater extent than GDC-0941 when combined with anti-neu antibody. These results demonstrate that a PI3K p110α-isoform-selective inhibitor is an effective adjunct to trastuzumab in the treatment of HER2-positive breast cancer.

Targeting the PI3K Signalling as a Therapeutic Strategy in Colorectal Cancer

Colorectal cancer (CRC) remains one of the leading causes of cancer mortality worldwide. Regarded as a heterogeneous disease, a number of biomarkers have been proposed to help in the stratification of CRC patients and to enable the selection of the best therapy for each patient towards personalized therapy. However, although the molecular mechanisms underlying the development of CRC have been elucidated, the therapeutic strategies available for these patients are still quite limited. Thus, over the last few years, a multitude of novel targets and therapeutic strategies have emerged focusing on deregulated molecules and pathways that are implicated in cell growth and survival. Particularly relevant in CRC are the activating mutations in the oncogene PIK3CA that frequently occur in concomitancy with KRAS and BRAF mutations and that lead to deregulation of the major signalling pathways PI3K and MAPK, downstream of EGFR. This review focus on the importance of the PI3K signalling in CRC development, on the current knowledge of PI3K inhibition as a therapeutic approach in CRC and on the implications PI3K signalling molecules may have as potential biomarkers and as new targets for directed therapies in CRC patients.

Gastric cancer management: Kinases as a target therapy

The molecular diagnostics revolution has reshaped the practice of oncology by facilitating the identification of genetic, epigenetic and proteomic modifications correlated with cancer, thus delineating 'oncomaps' for various cancer types. These advances have enhanced our understanding of gastric cancer, one of the most fatal diseases worldwide, and culminated in the approval of novel molecular therapies such as trastuzumab. Gastric tumours display recurrent aberrations in key kinase oncogenes such as Her2, epidermal growth factor receptor (EGFR), PI3K, mTOR or c-Met, suggesting that these receptors are amenable to inhibition using specific drug agents. In this review, we examine the mutational landscape of gastric cancer, the use of kinase inhibitors as targeted therapies in gastric tumours and the clinical trials underway for novel inhibitors, highlighting successes, failures and future directions.

Biomarkers of Everolimus Sensitivity in Hormone Receptor-Positive Breast Cancer

Activation of the mammalian target of rapamycin (mTOR) signaling pathway is an important mechanism of resistance to endocrine therapy in breast cancer. Everolimus, an mTOR inhibitor, has been shown to increase the efficacy of endocrine therapy and overcome resistance to endocrine therapies. Clinical studies have suggested that everolimus combined with endocrine therapy prolongs progression-free survival in hormone receptor-positive breast cancer patients. However, because breast cancer includes a group of highly heterogeneous tumors, patients may have different responses to everolimus. Therefore, finding biomarkers that can predict a patient's positive response or resistance to everolimus is critical. Numerous preclinical studies have shown that PIK3CA/PTEN mutations are predictive of sensitivity to everolimus; however, clinical trials have not confirmed the correlation between mutation status and clinical response. KRAS or BRAF mutations can bypass the phosphatidylinositol 3-kinase pathway; therefore, mutations in KRAS or BRAF may lead to resistance to mTOR inhibitors, and preclinical studies have shown that PIK3CA mutant cells which also contain KRAS mutations are resistant to everolimus. However, there are no clinical data in breast cancer patients to support this conclusion. Therefore, large-scale clinical studies are needed to identify biomarkers of efficacy and resistance to everolimus.

Efficacy of buparlisib in treating breast cancer

INTRODUCTION

Breast cancer is the most frequent cancer in women. Despite a decline in breast cancer mortality, prognosis of advanced breast cancer remains poor. In a desperate need to improve breast cancer outcomes, newer agents that target molecular pathways are being tested. Deregulation of the phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) is frequently found in breast cancer. This can lead to resistance of endocrine therapy and anti-HER2 therapies. Targeting this pathway may restore sensitivity to these compounds. Buparlisib (BKM-120) is an orally active pan-PI3K inhibitor evaluated in different tumor types. Areas covered: Buparlisib is one of the most investigated PI3K inhibitors. Preclinical and clinical studies of buparlisib in breast cancer are analyzed and discussed. This article reviews the status of buparlisib, completed and ongoing trials, and its safety. Expert opinion: PI3K inhibitors show promising results in breast cancer. However, we raise a number of issues including the identification of biomarkers to predict treatment response and strategies to counteract resistance. Moreover, its toxicity profile could limit its extensive use.

A Multicenter Phase I Study Evaluating Dual PI3K and BRAF Inhibition with PX-866 and Vemurafenib in Patients with Advanced BRAF V600-Mutant Solid Tumors

Purpose: The objectives of the study were to evaluate the safety of daily oral PX-866 in combination with twice daily vemurafenib and to identify potential predictive biomarkers for this novel combination.Experimental Design: We conducted a phase I, open-label, dose-escalation study in patients with advanced BRAF V600-mutant solid tumors. PX-866 was administered on a continuous schedule in combination with vemurafenib. Patients underwent a baseline and on-treatment biopsy after 1-week of PX-866 monotherapy for biomarker assessment.Results: Twenty-four patients were enrolled. The most common treatment-related adverse events were gastrointestinal side effects. One dose-limiting toxicity (DLT) of grade 3 rash and one DLT of grade 3 pancreatitis were observed in cohort 2 (PX-866 6 mg daily; vemurafenib 960 mg twice daily) and cohort 3 (PX-866 8 mg daily; vemurafenib 960 mg twice daily), respectively. Of 23 response-evaluable patients, seven had confirmed partial responses (PR), 10 had stable disease, and six had disease progression. Decreases in intratumoral pAKT expression were observed following treatment with PX-866. Patients who achieved PRs had higher rates of PTEN loss by IHC (80% vs. 58%) and pathogenic PTEN mutations and/or deletions (57% vs. 25%). Two patients with durable PRs had an increase in intratumoral CD8⁺ T-cell infiltration following treatment with PX-866.Conclusions: PX-866 was well tolerated at its maximum tolerated single-agent dose when given in combination with a modified dose of vemurafenib (720 mg twice daily). Response to treatment appeared to be associated with PTEN loss and treatment with PX-866 seemed to increase CD8⁺ T-cell infiltration in some patients. Clin Cancer Res; 24(1); 22-32. ©2017 AACR.

First-in-human trial of the PI3Kβ-selective inhibitor SAR260301 in patients with advanced solid tumors

BACKGROUND

Phosphoinositide 3-kinase (PI3K) β is the dominant isoform for PI3K activity in many phosphatase and tensin homolog (PTEN)-deficient tumor models. This was a first-in-human study to determine the maximum tolerated dose, safety, pharmacokinetics (PK), pharmacodynamics, and preliminary activity of SAR260301, a potent PI3Kβ-selective inhibitor (clinicaltrials.gov identifier NCT01673737).

METHODS

Successive cohorts of patients with advanced solid tumors received increasing doses of oral SAR260301 according to a Bayesian escalation with an overdose-control process based on the occurrence of dose-limiting toxicity in the first 28-day cycle. Adverse events, tumor response, PK, and the effect of food on PK were evaluated. Target engagement was assessed in platelets. Physiologically-based PK modeling was used for exposure predictions.

RESULTS

Twenty-one patients received treatment at doses ranging from 100 mg once daily to 440 mg/m² twice daily. Dose-limiting toxicities included 1 episode of grade 3 pneumonitis (400 mg twice daily) and 1 grade 3 γ-glutamyltransferase increase (600 mg twice daily). The maximum tolerated dose was not reached. The most frequently occurring treatment-related adverse events were nausea, vomiting, and diarrhea (14% each). Pharmacologically active concentrations were reached, but SAR260301 was rapidly cleared, and exposures associated with antitumor activity in preclinical models were not maintained at the highest dose tested. Food further decreased SAR260301 exposure.

CONCLUSIONS

SAR260301 had an acceptable safety profile, but exposure sufficient to inhibit the PI3K pathway was unachievable because of rapid clearance, and clinical development was terminated. These results demonstrate the importance of PK and pharmacodynamic assessments in early drug development. Cancer 2018;124:315-24. © 2017 American Cancer Society.

Phosphoinositide 3-kinase (PI3K) pathway inhibitors in solid tumors: From laboratory to patients

The phosphoinositide 3-kinase (PI3K) pathway is an intracellular signaling pathway that has regulatory roles in cell survival, proliferation, and differentiation, and a critical role in tumorigenesis. In cancer, multiple studies have investigated the therapeutic targeting of the PI3K pathway, and multiple inhibitors targeting PI3K and its isoforms, protein kinase B/AKT, mammalian target of rapamycin (mTOR), and other pathway proteins have been developed. For the treatment of solid tumors, only allosteric mTOR inhibitors, such as everolimus and temsirolimus, are currently approved for clinical use. This review describes the PI3K inhibitors that have progressed from the laboratory to late-stage clinical trials, and discusses the challenges that have prevented other compounds from doing the same. Challenges to the therapeutic effectiveness of some PI3K inhibitors include the absence of reliable and effective biomarkers, their limited efficacy as single agents, insufficient development of rational therapeutic combinations, the use of schedules with a variety of off-target effects, and suboptimal therapeutic exposures. Therefore, with regard to PI3K inhibitors currently in late-stage clinical trials, the identification of appropriate biomarkers of efficacy and the development of optimal combination regimens and dosing schedules are likely to be important for graduation into clinical practice.

Activation of phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin pathway and response to everolimus in endocrine receptor-positive metastatic breast cancer - A retrospective pilot analysis and viewpoint

Introduction:

Biomarkers predictive of response to mechanistic target of rapamycin (mTOR) inhibitor, everolimus, in endocrine receptor (ER)-positive metastatic breast cancer (MBC) are a work in progress. We evaluated the feasibility of directly measuring mTOR activity and phosphatase and tensin homolog (PTEN) expression and correlating their expression with response and survival.

Materials and Methods:

MBC patients who received everolimus with endocrine therapy (ET) after progression on an aromatase inhibitor and had adequate tissue preservation for estimation of mTOR activity and PTEN expression were selected for analysis from a prospectively maintained database. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan–Meier method, and correlation between mTOR activity and PTEN expression with survival was done by log-rank test.

Results:

Thirteen ER-positive MBC patients were available for analysis. PTEN expression was lost in 11/13 (84.6%) patients and retained in 2/13 patients (15.4%). mTOR activity was absent in four patients (30.7%), weak in six patients (46.1%), and moderate in 3 patients (23.2%). Median PFS for the entire population was 2.5 months while median OS was not reached. Patients with an absent mTOR activity showed a longer PFS (5 vs. 1.5 vs. 2 months) than those with weak and moderate activity, respectively (P = 0.043). There was no correlation between loss of PTEN expression and PFS.

Conclusions:

Measurement of direct mTOR activity in patients with MBC receiving everolimus/ET combination appears feasible. Absent mTOR activity may predict for longer PFS with everolimus-ET combination and requires further study.