Perifosine plus docetaxel in patients with platinum and taxane resistant or refractory high-grade epithelial ovarian cancer

Low-Dose Perifosine, a Phase II Phospholipid Akt Inhibitor, Selectively Sensitizes Drug-Resistant ABCB1-Overexpressing Cancer Cells

We identified drugs or mechanisms targeting ABCB1 (or P-glycoprotein; P-gp)-overexpressing drug-resistant cancer populations, given that these cells play a key role in tumor recurrence. Specifically, we searched for Akt inhibitors that could increase cytotoxicity in P-gp-overexpressing drug-resistant cancer cells. We performed cytotoxicity assays using five cell lines: 1. MCF-7/ADR, 2. KBV20C cancer cells (P-gp overexpression, vincristine [VIC] resistance, and GSK690693-resistance), 3. MCF-7, 4. normal HaCaT cells (non-P-gp-overexpressing, VIC-sensitive, and GSK690693-sensitive), and 5. MDA-MB-231 cancer cells (non-P-gp overexpression, relatively VIC-resistance, and GSK690693-sensitive). Herein, we found that low-dose perifosine markedly and selectively sensitizes both MCF-7/ADR and KBV20C drug-resistant cancer cells exhibiting P-gp overexpression. Compared with other Akt inhibitors (AZD5363, BKM120, and GSK690693), low-dose perifosine specifically sensitized P-gp-overexpressing resistant MCF-7/ADR cancer cells. Conversely, Akt inhibitors (other than perifosine) could enhance sensitization effects in drugsensitive MCF-7 and HaCaT cells. Considering that perifosine has both an alkyl-phospholipid structure and is an allosteric inhibitor for membrane-localizing Akt-targeting, we examined structurally and functionally similar Akt inhibitors (miltefosine and MK-2206). However, we found that these inhibitors were non-specific, suggesting that the specificity of perifosine in P-gp-overexpressing resistant cancer cells is unrelated to phospholipid localizing membranes or allosteric inhibition. Furthermore, we examined the molecular mechanism of low-dose perifosine in drug-resistant MCF-7/ADR cancer cells. MCF-7/ADR cells exhibited increased apoptosis via G2 arrest and autophagy induction. However, no increase in P-gp-inhibitory activity was observed in drug-resistant MCF-7/ADR cancer cells. Single low-dose perifosine treatment exerted a sensitization effect similar to co-treatment with VIC in P-gp-overexpressing drug-resistant MCF-7/ADR cancer cells, suggesting that single treatment with low-dose perifosine is a more powerful tool against P-gp-overexpressing drug-resistant cancer cells. These findings could contribute to its clinical use as a first-line treatment, explicitly targeting P-gp-overexpressing resistant cancer populations in heterogeneous tumor populations. Therefore, perifosine may be valuable in delaying or reducing cancer recurrence by targeting P-gp-overexpressing drug-resistant cancer cells.

Interleukin-6 Modulation in Ovarian Cancer Necessitates a Targeted Strategy: From the Approved to Emerging Therapies

Despite significant advances in treatments, ovarian cancer (OC) remains one of the most prevalent and lethal gynecological cancers in women. The frequent detection at the advanced stages has contributed to low survival rates, resistance to various treatments, and disease recurrence. Thus, a more effective approach is warranted to combat OC. The cytokine Interleukin-6 (IL6) has been implicated in various stages of OC development. High IL6 levels are also correlated with a lower survival rate in OC patients. In this current review, we summarized the pivotal roles of IL6 in OC, including the initiation, development, invasion, metastasis, and drug resistance mechanisms. This article systematically highlights how targeting IL6 improves OC outcomes by altering various cancer processes and reports the ongoing clinical trials that would further shape the IL6-based targeted therapies. This review also suggests how combining IL6-targeted therapies with other therapeutic strategies could further enhance their efficacy to combat OC.

An Update on Physiopathological Roles of Akt in the ReprodAKTive Mammalian Ovary

The phosphoinositide 3-kinase (PI3K)/Akt pathway is a key signaling cascade responsible for the regulation of cell survival, proliferation, and metabolism in the ovarian microenvironment. The optimal finetuning of this pathway is essential for physiological processes concerning oogenesis, folliculogenesis, oocyte maturation, and embryo development. The dysregulation of PI3K/Akt can impair molecular and structural mechanisms that will lead to follicle atresia, or the inability of embryos to reach later stages of development. Due to its pivotal role in the control of cell proliferation, apoptosis, and survival mechanisms, the dysregulation of this molecular pathway can trigger the onset of pathological conditions. Among these, we will focus on diseases that can harm female fertility, such as polycystic ovary syndrome and premature ovarian failure, or women's general health, such as ovarian cancer. In this review, we report the functions of the PI3K/Akt pathway in both its physiological and pathological roles, and we address the existing application of inhibitors and activators for the balancing of the molecular cascade in ovarian pathological environments.

Deciphering resistance mechanisms and novel strategies to overcome drug resistance in ovarian cancer: a comprehensive review

Ovarian cancer is among the most lethal gynecological cancers, primarily due to the lack of specific symptoms leading to an advanced-stage diagnosis and resistance to chemotherapy. Drug resistance (DR) poses the most significant challenge in treating patients with existing drugs. The Food and Drug Administration (FDA) has recently approved three new therapeutic drugs, including two poly (ADP-ribose) polymerase (PARP) inhibitors (olaparib and niraparib) and one vascular endothelial growth factor (VEGF) inhibitor (bevacizumab) for maintenance therapy. However, resistance to these new drugs has emerged. Therefore, understanding the mechanisms of DR and exploring new approaches to overcome them is crucial for effective management. In this review, we summarize the major molecular mechanisms of DR and discuss novel strategies to combat DR.

Pharmacokinetics of Novel Furoxan/Coumarin Hybrids in Rats Using LC-MS/MS Method and Physiologically Based Pharmacokinetic Model

Novel furoxan/coumarin hybrids were synthesized, and pharmacologic studies showed that the compounds displayed potent antiproliferation activities via downregulating both the phosphatidylinositide 3-kinase (PI3K) pathway and the mitogen-activated protein kinase (MAPK) pathway. To investigate the preclinical pharmacokinetic (PK) properties of three candidate compounds (CY-14S-4A83, CY-16S-4A43, and CY-16S-4A93), liquid chromatography, in tandem with the mass spectrometry LC-MS/MS method, was developed and validated for the simultaneous determination of these compounds. The absorption, distribution, metabolism, and excretion (ADME) properties were investigated in in vitro studies and in rats. Meanwhile, physiologically based pharmacokinetic (PBPK) models were constructed using only in vitro data to obtain detailed PK information. Good linearity was observed over the concentration range of 0.01−1.0 μg/mL. The free drug fraction (fu) values of the compounds were less than 3%, and the clearance (CL) values were 414.5 ± 145.7 mL/h/kg, 2624.6 ± 648.4 mL/h/kg, and 500.6 ± 195.2 mL/h/kg, respectively. The predicted peak plasma concentration (Cmax) and the area under the concentration-time curve (AUC) were overestimated for the CY-16S-4A43 PBPK model compared with the experimental ones (fold error > 2), suggesting that tissue accumulation and additional elimination pathways may exist. In conclusion, the LC-MS/MS method was successively applied in the preclinical PK studies, and the detailed information from PBPK modeling may improve decision-making in subsequent new drug development.

Targeting the PI3K/AKT/mTOR pathway in epithelial ovarian cancer, therapeutic treatment options for platinum-resistant ovarian cancer

The survival rates for women with ovarian cancer have shown scant improvement in recent years, with a 5-year survival rate of less than 40% for women diagnosed with advanced ovarian cancer. High-grade serous ovarian cancer (HGSOC) is the most lethal subtype where the majority of women develop recurrent disease and chemotherapy resistance, despite over 70%-80% of patients initially responding to platinum-based chemotherapy. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway regulates many vital processes such as cell growth, survival and metabolism. However, this pathway is frequently dysregulated in cancers including different subtypes of ovarian cancer, through amplification or somatic mutations of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), amplification of AKT isoforms, or deletion or inactivation of PTEN. Further evidence indicates a role for the PI3K/AKT/mTOR pathway in the development of chemotherapy resistance in ovarian cancer. Thus, targeting key nodes of the PI3K/AKT/mTOR pathway is a potential therapeutic prospect. In this review, we outline dysregulation of PI3K signaling in ovarian cancer, with a particular emphasis on HGSOC and platinum-resistant disease. We review pre-clinical evidence for inhibitors of the main components of the PI3K pathway and highlight past, current and upcoming trials in ovarian cancers for different inhibitors of the pathway. Whilst no inhibitors of the PI3K/AKT/mTOR pathway have thus far advanced to the clinic for the treatment of ovarian cancer, several promising compounds which have the potential to restore platinum sensitivity and improve clinical outcomes for patients are under evaluation and in various phases of clinical trials.

Evaluation of stromal cell infiltration in the tumor microenvironment enable prediction of treatment sensitivity and prognosis in colon cancer

Current clinical factors for screening candidates that might benefit from adjuvant chemotherapy in colon cancer are inadequate. Tumor microenvironment, especially the stromal components, has the potential to determine treatment response. However, clinical translation of the tumor-associated stromal characterization into a practical biomarker for helping treatment decision has not been established. Using machine learning, we established a novel 31-gene signature, called stromal cell infiltration intensity score (SIIS), to distinguish patients characterized by the enrichment of abundant stromal cells in five colon cancer datasets from GEO (N = 990). Patients with high-SIIS were at higher risk for recurrence and mortality, and could not benefit from adjuvant chemotherapy due to their intrinsic drug resistance; however, the opposite was reported for patients with low-SIIS. The role of SIIS in detection of patients with high stromal cell infiltration and reduced drug efficiency was consistently validated in the TCGA-COAD cohort (N = 382), Sun Yat-sen University Cancer Center cohort (N = 30), and could also be observed in TCGA pan-cancer settings (N = 4898) and four independent immunotherapy cohorts (N = 467). Based on multi-omics data analysis and the CRISPR library screen, we reported that lack of gene mutation, hypomethylation in ADCY4 promoter region, activation of WNT-PCP pathway and SIAH2-GPX3 axis were potential mechanisms responsible for the chemoresistance of patients within high-SIIS group. Our findings demonstrated that SIIS provide an important reference for those making treatment decisions for such special patients.

Genetic alterations and their therapeutic implications in epithelial ovarian cancer

BACKGROUND

Genetic alterations for epithelial ovarian cancer are insufficiently characterized. Previous studies are limited regarding included histologies, gene numbers, copy number variant (CNV) detection, and interpretation of pathway alteration patterns of individual patients.

METHODS

We sequenced 410 genes to analyze mutations and CNV of 82 ovarian carcinomas, including high-grade serous (n = 37), endometrioid (n = 22) and clear cell (n = 23) histologies. Eligibility for targeted therapy was determined for each patient by a pathway-based approach. The analysis covered DNA repair, receptor tyrosine kinase, PI3K/AKT/MTOR, RAS/MAPK, cell cycle, and hedgehog pathways, and included 14 drug targets.

RESULTS

Postulated PARP, MTOR, and CDK4/6 inhibition sensitivity were most common. BRCA1/2 alterations, PTEN loss, and gain of PIK3CA and CCND1 were characteristic for high-grade serous carcinomas. Mutations of ARID1A, PIK3CA, and KRAS, and ERBB2 gain were enriched in the other histologies. PTEN mutations and high tumor mutational burden were characteristic for endometrioid carcinomas. Drug target downstream alterations impaired actionability in all histologies, and many alterations would not have been discovered by key gene mutational analysis. Individual patients often had more than one actionable drug target.

CONCLUSIONS

Genetic alterations in ovarian carcinomas are complex and differ among histologies. Our results aid the personalization of therapy and biomarker analysis for clinical studies, and indicate a high potential for combinations of targeted therapies.

Cellular Mechanism of Gene Mutations and Potential Therapeutic Targets in Ovarian Cancer

Ovarian cancer is a common and complex malignancy with poor prognostic outcome. Most women with ovarian cancer are diagnosed with advanced stage disease due to a lack of effective detection strategies in the early stage. Traditional treatment with cytoreductive surgery and platinum-based combination chemotherapy has not significantly improved prognosis and 5-year survival rates are still extremely poor. Therefore, novel treatment strategies are needed to improve the treatment of ovarian cancer patients. Recent advances of next generation sequencing technologies have both confirmed previous known mutated genes and discovered novel candidate genes in ovarian cancer. In this review, we illustrate recent advances in identifying ovarian cancer gene mutations, including those of TP53, BRCA1/2, PIK3CA, and KRAS genes. In addition, we discuss advances in targeting therapies for ovarian cancer based on these mutated genes in ovarian cancer. Further, we associate between detection of mutation genes by liquid biopsy and the potential early diagnostic value in ovarian cancer.

SPR965, a Dual PI3K/mTOR Inhibitor, as a Targeted Therapy in Ovarian Cancer

SPR965 is an inhibitor of PI3K and mTOR C1/C2 and has demonstrated anti-tumorigenic activity in a variety of solid tumors. We sought to determine the effects of SPR965 on cell proliferation and tumor growth in human serous ovarian cancer cell lines and a transgenic mouse model of high grade serous ovarian cancer (KpB model) and identify the underlying mechanisms by which SPR965 inhibits cell and tumor growth. SPR965 showed marked anti-proliferative activity by causing cell cycle arrest and inducing cellular stress in ovarian cancer cells. Treatment with SPR965 significantly inhibited tumor growth in KpB mice, accompanied by downregulation of Ki67 and VEGF and upregulation of Bip expression in ovarian tumors. SPR965 also inhibited adhesion and invasion through induction of the epithelial–mesenchymal transition process. As expected, downregulation of phosphorylation of AKT and S6 was observed in SPR965-treated ovarian cancer cells and tumors. Our results suggest that SPR965 has significant anti-tumorigenic effects in serous ovarian cancer in vitro and in vivo. Thus, SPR965 should be evaluated as a promising targeted agent in future clinical trials of ovarian cancer.

Pharmacologic inhibition of Akt in combination with chemotherapeutic agents effectively induces apoptosis in ovarian and endometrial cancer cell lines

The PI3K/Akt signaling pathway, the most frequently altered signaling system in human cancer, is a crucial inducer of dysregulated proliferation and neoplastic processes; however, few therapeutic strategies using PI3K/Akt inhibitors singly have been shown to be effective. The purpose of this paper was to underline the potential benefit of pharmacological modulation of the PI3K/Akt pathway when combined with specific chemotherapeutic regimens. We have studied the ability of NVP‐BEZ235 (PI3K/mTOR inhibitor) and AZD5363 (Akt inhibitor) in the sensitization of cancer cells to cisplatin and doxorubicin. Our results show that NVP‐BEZ235 sensitizes cells preferentially to cisplatin while AZD5363 sensitizes cells to doxorubicin. At equal concentrations (5 μm), both inhibitors reduce ribosomal protein S6 phosphorylation, but AZD5363 is more effective in reducing GSK3β phosphorylation as well as S6 phosphorylation. Additionally, AZD5363 is capable of inducing FOXO1 and p53 nuclear localization and reduces BAD phosphorylation, which is generally increased by cisplatin and doxorubicin. Finally, the combination of AZD5363 and doxorubicin induces apoptosis in cells and robustly reduces cell ability to clonally replicate, which underlines a potential cooperative effect of the studied compounds.

Dual Gene Delivery Reagents From Antiproliferative Alkylphospholipids for Combined Antitumor Therapy

Alkylphospholipids (APLs) have elicited great interest as antitumor agents due to their unique mode of action on cell membranes. However, their clinical applications have been limited so far by high hemolytic activity. Recently, cationic prodrugs of erufosine, a most promising APL, have been shown to mediate efficient intracellular gene delivery, while preserving the antiproliferative properties of the parent APL. Here, cationic prodrugs of the two APLs that are currently used in the clinic, miltefosine, and perifosine, are investigated and compared to the erufosine prodrugs. Their synthesis, stability, gene delivery and self-assembly properties, and hemolytic activity are discussed in detail. Finally, the potential of the pro-miltefosine and pro-perifosine compounds M_E12 and P_E12 in combined antitumor therapy is demonstrated using pUNO1-hTRAIL, a plasmid DNA encoding TRAIL, a member of the TNF superfamily. With these pro-APL compounds, we provide a proof of concept for a new promising strategy for cancer therapy combining gene therapy and APL-based chemotherapy.

Erufosine (ErPC3) Cationic Prodrugs as Dual Gene Delivery Reagents for Combined Antitumor Therapy

Sixteen cationic prodrugs of the antitumor alkylphospholipid (APL) erufosine were rationally synthesized to provide original gene delivery reagents with improved cytotoxicity profile. The DNA complexation properties of these cationic lipids were determined and associated transfection rates were measured. Furthermore, the self-assembly properties of the pro-erufosine compounds were investigated and their critical aggregation concentration was determined. Their hydrolytic stability under pH conditions mimicking the extracellular environment and the late endosome milieu was measured. Hemolytic activity and cytotoxicity of the compounds were investigated. The results obtained in various cell lines demonstrate that the prodrugs of erufosine display antineoplastic activity similar to that of the parent antitumor drug but are not associated with hemolytic toxicity, which is a dose-limiting side effect of APLs and a major obstacle to their use in anticancer therapeutic regimen. Furthermore, by using lipoplexes prepared from a prodrug of erufosine and a plasmid DNA encoding a pro-apoptotic protein (TRAIL), evidence was provided for selective cytotoxicity towards tumor cells while nontumor cells were resistant. This study demonstrates that the combination approach involving well tolerated erufosine cationic prodrugs and cancer gene therapy holds significant promise in tumor therapy.

Alkylphospholipids are Signal Transduction Modulators with Potential for Anticancer Therapy

BACKGROUND

Alkylphospholipids (APLs) are synthetically derived from cell membrane components, which they target and thus modify cellular signalling and cause diverse effects. This study reviews the mechanism of action of anticancer, antiprotozoal, antibacterial and antiviral activities of ALPs, as well as their clinical use.

METHODS

A literature search was used as the basis of this review.

RESULTS

ALPs target lipid rafts and alter phospholipase D and C signalling cascades, which in turn will modulate the PI3K/Akt/mTOR and RAS/RAF/MEK/ERK pathways. By feedback coupling, the SAPK/JNK signalling chain is also affected. These changes lead to a G2/M phase cell cycle arrest and subsequently induce programmed cell death. The available knowledge on inhibition of AKT phosphorylation, mTOR phosphorylation and Raf down-regulation renders ALPs as attractive candidates for modern medical treatment, which is based on individualized diagnosis and therapy. Corresponding to their unusual profile of activities, their side effects result from cholinomimetic activity mainly and focus on the gastrointestinal tract. These aspects together with their bone marrow sparing features render APCs well suited for modern combination therapy. Although the clinical success has been limited in cancer diseases so far, the use of miltefosine against leishmaniosis is leading the way to better understanding their optimized use.

CONCLUSION

Recent synthetic programs generate congeners with the increased therapeutic ratio, liposomal formulations, as well as diapeutic (or theranostic) derivatives with optimized properties. It is anticipated that these innovative modifications will pave the way for the further successful development of ALPs.

Targeting AKT for cancer therapy

Introduction: Targeted therapies in cancer aim to inhibit specific molecular targets responsible for enhanced tumor growth. AKT/PKB (protein kinase B) is a serine threonine kinase involved in several critical cellular pathways, including survival, proliferation, invasion, apoptosis, and angiogenesis. Although phosphatidylinositol-3 kinase (PI3K) is the key regulator of AKT activation, numerous stimuli and kinases initiate pro-proliferative AKT signaling which results in the activation of AKT pathway to drive cellular growth and survival. Activating mutations and amplification of components of the AKT pathway are implicated in the pathogenesis of many cancers including breast and ovarian. Given its importance, AKT, it has been validated as a promising therapeutic target.Areas covered: This article summarizes AKT's biological function and different classes of AKT inhibitors as anticancer agents. We also explore the efficacy of AKT inhibitors as monotherapies and in combination with cytotoxic and other targeted therapies.Expert opinion: The complex mechanism following AKT inhibition requires the addition of other therapies to prevent resistance and improve clinical response. Further studies are necessary to determine additional rational combinations that can enhance efficacy of AKT inhibitors, potentially by targeting compensatory mechanisms, and/or enhancing apoptosis. The identification of biomarkers of response is essential for the development of successful therapeutics.

New Challenges in Tumor Mutation Heterogeneity in Advanced Ovarian Cancer by a Targeted Next-Generation Sequencing (NGS) Approach

Next-generation sequencing (NGS) technology has advanced knowledge of the genomic landscape of ovarian cancer, leading to an innovative molecular classification of the disease. However, patient survival and response to platinum-based treatments are still not predictable based on the tumor genetic profile. This retrospective study characterized the repertoire of somatic mutations in advanced ovarian cancer to identify tumor genetic markers predictive of platinum chemo-resistance and prognosis. Using targeted NGS, 79 primary advanced (III-IV stage, tumor grade G2-3) ovarian cancer tumors, including 64 high-grade serous ovarian cancers (HGSOCs), were screened with a 26 cancer-genes panel. Patients, enrolled between 1995 and 2011, underwent primary debulking surgery (PDS) with optimal residual disease (RD < 1 cm) and platinum-based chemotherapy as first-line treatment. We found a heterogeneous mutational landscape in some uncommon ovarian histotypes and in HGSOC tumor samples with relevance in predicting platinum sensitivity. In particular, we identified a poor prognostic signature in patients with HGSOC harboring concurrent mutations in two driver actionable genes of the panel. The tumor heterogeneity described, sheds light on the translational potential of targeted NGS approach for the identification of subgroups of patients with distinct therapeutic vulnerabilities, that are modulated by the specific mutational profile expressed by the ovarian tumor.

Role of the PI3K/AKT/mTOR signaling pathway in ovarian cancer: Biological and therapeutic significance

Ovarian cancer (OC) is a lethal gynecological cancer. The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway plays an important role in the regulation of cell survival, growth, and proliferation. Irregularities in the major components of the PI3K/AKT/mTOR signaling pathway are common in human cancers. Despite the availability of strong pre-clinical and clinical data of PI3K/AKT/mTOR pathway inhibitors in OC, there is no FDA approved inhibitor available for the treatment of OC. Here, we outline the importance of PI3K/AKT/mTOR signaling pathway in OC tumorigenesis, proliferation and progression, and pre-clinical and clinical experience with several PI3K/AKT/mTOR pathway inhibitors in OC.

Genomic heterogeneity and efficacy of PI3K pathway inhibitors in patients with gynaecological cancer

Objectives

Aberrant PI3K/AKT/mTOR activation is common in gynaecological malignancies. However, predictive biomarkers of response to PI3K pathway inhibitors (PAMi) have yet to be identified.

Methods

We analysed the outcomes of patients with advanced gynaecological cancer with available genomic data, treated with PAMi as single agents or in combination in phase I clinical trials. Clinical relevance of the PIK3CA mutant allele fraction (MAF) was investigated. MAF of each variant was normalised for tumour purity in the sample (adjMAFs) to infer clonality of PIK3CA mutations, defined as clonal (≥0.4) or subclonal (<0.4).

Results

A total of 50 patients with gynaecological cancer (24 ovarian; 15 endometrial; 11 cervical) with available targeted mutation profiling were selected. PAMi therapy was matched to PIK3CA/PTEN mutation in 30 patients (60%). The overall response rate, median time to progression (mTTP) and clinical benefit rate (CBR) of the entire population were 10% (N=5), 3.57 months (2.57-4.4) and 40% (N=18), respectively. Genotype-matched therapy did not lead to a favourable CBR (OR 0.91, p=1 (0.2-3.7)) or mTTP (3.57 months (2.6-4.4) vs 3.73 months (1.9-13.2); HR 1.41; p=0.29). We did not detect differences in mTTP according to therapy or PIK3CA codon mutation (HR 1.71, p=0.24). Overall, 41% of patients had a TTP ratio (TTP PAMi/TTP on immediately prior or subsequent palliative chemotherapy) ≥1.3, without statistically significant differences according to tumour type (p=0.39), molecular alteration status (p=0.13) or therapy (p=0.54). In univariate analysis, genotype-matched therapy in patients with PIK3CA clonal events was associated with improved mTTP (HR 3.6; p=0.03).

Conclusions

Our study demonstrates that patients with advanced gynaecological cancer, refractory to standard therapies, achieved meaningful clinical benefit from PAMi. The impact of PI3KCA clonality on response to selected PAMi in patients with gynaecological cancer deserves further investigation.

Genomic heterogeneity and efficacy of PI3K pathway inhibitors in patients with gynaecological cancer

OBJECTIVES

Aberrant PI3K/AKT/mTOR activation is common in gynaecological malignancies. However, predictive biomarkers of response to PI3K pathway inhibitors (PAMi) have yet to be identified.

METHODS

We analysed the outcomes of patients with advanced gynaecological cancer with available genomic data, treated with PAMi as single agents or in combination in phase I clinical trials. Clinical relevance of the PIK3CA mutant allele fraction (MAF) was investigated. MAF of each variant was normalised for tumour purity in the sample (adjMAFs) to infer clonality of PIK3CA mutations, defined as clonal (≥0.4) or subclonal (<0.4).

RESULTS

A total of 50 patients with gynaecological cancer (24 ovarian; 15 endometrial; 11 cervical) with available targeted mutation profiling were selected. PAMi therapy was matched to PIK3CA/PTEN mutation in 30 patients (60%). The overall response rate, median time to progression (mTTP) and clinical benefit rate (CBR) of the entire population were 10% (N=5), 3.57 months (2.57-4.4) and 40% (N=18), respectively. Genotype-matched therapy did not lead to a favourable CBR (OR 0.91, p=1 (0.2-3.7)) or mTTP (3.57 months (2.6-4.4) vs 3.73 months (1.9-13.2); HR 1.41; p=0.29). We did not detect differences in mTTP according to therapy or PIK3CA codon mutation (HR 1.71, p=0.24). Overall, 41% of patients had a TTP ratio (TTP PAMi/TTP on immediately prior or subsequent palliative chemotherapy) ≥1.3, without statistically significant differences according to tumour type (p=0.39), molecular alteration status (p=0.13) or therapy (p=0.54). In univariate analysis, genotype-matched therapy in patients with PIK3CA clonal events was associated with improved mTTP (HR 3.6; p=0.03).

CONCLUSIONS

Our study demonstrates that patients with advanced gynaecological cancer, refractory to standard therapies, achieved meaningful clinical benefit from PAMi. The impact of PI3KCA clonality on response to selected PAMi in patients with gynaecological cancer deserves further investigation.

Genomic heterogeneity and efficacy of PI3K pathway inhibitors in patients with gynaecological cancer

OBJECTIVES

Aberrant PI3K/AKT/mTOR activation is common in gynaecological malignancies. However, predictive biomarkers of response to PI3K pathway inhibitors (PAMi) have yet to be identified.

METHODS

We analysed the outcomes of patients with advanced gynaecological cancer with available genomic data, treated with PAMi as single agents or in combination in phase I clinical trials. Clinical relevance of the PIK3CA mutant allele fraction (MAF) was investigated. MAF of each variant was normalised for tumour purity in the sample (adjMAFs) to infer clonality of PIK3CA mutations, defined as clonal (≥0.4) or subclonal (<0.4).

RESULTS

A total of 50 patients with gynaecological cancer (24 ovarian; 15 endometrial; 11 cervical) with available targeted mutation profiling were selected. PAMi therapy was matched to PIK3CA/PTEN mutation in 30 patients (60%). The overall response rate, median time to progression (mTTP) and clinical benefit rate (CBR) of the entire population were 10% (N=5), 3.57 months (2.57-4.4) and 40% (N=18), respectively. Genotype-matched therapy did not lead to a favourable CBR (OR 0.91, p=1 (0.2-3.7)) or mTTP (3.57 months (2.6-4.4) vs 3.73 months (1.9-13.2); HR 1.41; p=0.29). We did not detect differences in mTTP according to therapy or PIK3CA codon mutation (HR 1.71, p=0.24). Overall, 41% of patients had a TTP ratio (TTP PAMi/TTP on immediately prior or subsequent palliative chemotherapy) ≥1.3, without statistically significant differences according to tumour type (p=0.39), molecular alteration status (p=0.13) or therapy (p=0.54). In univariate analysis, genotype-matched therapy in patients with PIK3CA clonal events was associated with improved mTTP (HR 3.6; p=0.03).

CONCLUSIONS

Our study demonstrates that patients with advanced gynaecological cancer, refractory to standard therapies, achieved meaningful clinical benefit from PAMi. The impact of PI3KCA clonality on response to selected PAMi in patients with gynaecological cancer deserves further investigation.

Identification of pathway-based recurrence-associated signatures in optimally debulked patients with serous ovarian cancer

Serous ovarian cancer (SOC) is the most common form of the histological subtype of epithelial ovarian cancer, with the worst clinical outcome. Despite improvements in surgery and chemotherapy, most patients with SOC experience recurrence within 12-18 months of first-line treatment. Current studies are unable to robustly predict the recurrence of SOC, and more accurate predictive models are urgently required. We have, therefore, developed a novel pathway-structured model to predict the recurrence of SOC. We trained the model on a set of 333 patients and validated it in 3 diversified validation datasets of 403 patients. Genes significantly associated with recurrence within each pathway were identified using a Cox proportional hazards model based on LASSO estimation in the training dataset. Next, a pathway-structured scoring matrix was obtained after computation of the prognostic score for each pathway by fitting to the Cox proportional hazards model. With the pathway-structure scoring matrix as an input, the pathway-based recurrent signatures were identified using the Cox proportional hazards model based on LASSO estimation and the significant pathway-based signatures were externally validated in 3 independent datasets. Meanwhile, our pathway-structured model was compared with a commonly used gene-based model. Our results revealed that our 12 pathway-based signatures successfully predicted the recurrence of SOC with high accuracy in the training dataset and in the 3 validation datasets. Moreover, our pathway-structured model was superior to the gene-based model in 4 datasets. The pathways selected in our study will provide new insights into the pathogenesis and clinical treatments of SOC.

Proteomic and Bioinformatic Studies for the Characterization of Response to Pemetrexed in Platinum Drug Resistant Ovarian Cancer

Proteomics and bioinformatics are a useful combined technology for the characterization of protein expression level and modulation associated with the response to a drug and with its mechanism of action. The folate pathway represents an important target in the anticancer drugs therapy. In the present study, a discovery proteomics approach was applied to tissue samples collected from ovarian cancer patients who relapsed after the first-line carboplatin-based chemotherapy and were treated with pemetrexed (PMX), a known folate pathway targeting drug. The aim of the work is to identify the proteomic profile that can be associated to the response to the PMX treatment in pre-treatement tissue. Statistical metrics of the experimental Mass Spectrometry (MS) data were combined with a knowledge-based approach that included bioinformatics and a literature review through ProteinQuest™ tool, to design a protein set of reference (PSR). The PSR provides feedback for the consistency of MS proteomic data because it includes known validated proteins. A panel of 24 proteins with levels that were significantly different in pre-treatment samples of patients who responded to the therapy vs. the non-responder ones, was identified. The differences of the identified proteins were explained for the patients with different outcomes and the known PMX targets were further validated. The protein panel herein identified is ready for further validation in retrospective clinical trials using a targeted proteomic approach. This study may have a general relevant impact on biomarker application for cancer patients therapy selection.

Akt isoform specific effects in ovarian cancer progression

Ovarian cancer remains a significant therapeutic problem and novel, effective therapies are needed. Akt is a serine-threonine kinase that is overexpressed in numerous cancers, including ovarian. Mammalian cells express three Akt isoforms which are encoded by distinct genes. Although there are several Akt inhibitors in clinical trials, most indiscriminately target all isoforms. Current in vitro data and animal knockout experiments suggest that the Akt isoforms may have divergent roles. In this paper, we determined the isoform-specific functions of Akt in ovarian cancer cell proliferation in vitro and in ovarian cancer progression in vivo. For in vitro experiments, murine and human ovarian cancer cells were treated with Akt inhibitors and cell viability was assessed. We used two different in vivo approaches to identify the roles of Akt isoforms in ovarian cancer progression and their influence on the primary tumor and tumor microenvironment. In one experiment, wild-type C57Bl6 mice were orthotopically injected with ID8 cells with stable knockdown of Akt isoforms. In a separate experiment, mice null for Akt 1-3 were orthotopically injected with WT ID8 cells (Figure 1). Our data show that inhibition of Akt1 significantly reduced ovarian cancer cell proliferation and inhibited tumor progression in vivo. Conversely, disruption of Akt2 increased tumor growth. Inhibition of Akt3 had an intermediate phenotype, but also increased growth of ovarian cancer cells. These data suggest that there is minimal redundancy between the Akt isoforms in ovarian cancer progression. These findings have important implications in the design of Akt inhibitors for the effective treatment of ovarian cancer.

Impact of Recurrence of Ovarian Cancer on Quality of Life and Outlook for the Future

OBJECTIVE

Ovarian cancer recurs in most patients, with a 5-year survival rate less than 30%. Quality of life is an increasingly important issue in patients with cancer, but there are limited data in women with recurrent ovarian cancer in this regard.

MATERIALS AND METHODS

We used an ad hoc questionnaire to compare changes in health perceptions, burden of disease, and expectations for the future quality of life in women with and without recurrence of ovarian cancer. A total of 173 women were included, 116 with relapse and 57 without, undergoing follow-up in a routine clinical setting.

RESULTS

Substantial differences were seen in self-assessed health status between women with and without recurrence; 33.6% and 82.4% of women with and without recurrence rated their health as good to excellent, respectively. More patients with recurrence of disease reported limitations in moderate activity than those without. Furthermore, 79.0% of women without recurrence reported that pain did not affect or only slightly affected daily activities, compared with 28.2% with recurrence. Most women with recurrence (59.5%) reported that they were able to do less than they wanted to because of their emotional status compared with only 15.8% of women without recurrence. In addition, 66.4% of women with recurrence referred that they had problems concentrating at work and home versus 26.3% of women without recurrence.

CONCLUSIONS

From this survey, it is clear that relapse of disease has a negative psychological and physical impact, highlighting the importance of time without recurrence and the need for effective treatment in the long term.

Continuous anti-angiogenic therapy after tumor progression in patients with recurrent high-grade epithelial ovarian cancer: phase I trial experience

High-grade epithelial ovarian cancer (HG-EOC) is the most lethal gynecologic malignancy worldwide Once patients develop chemoresistance, effective novel strategies are required to improve prognosis We analyzed characteristics and outcomes of 242 consecutive patients with HG-EOC participating in 94 phase I clinical trials at The University of Texas MD Anderson Cancer Center. Baseline lactate dehydrogenase levels, albumin levels, and number of metastatic sites were independent predictors of overall survival (OS). Receiving more than 1 phase I protocol was associated with improved OS (p < 0.001). Regimens including a chemotherapeutic agent plus bevacizumab or Aurora A kinase inhibitor led to a median progression-free survival (PFS) duration of more than 6 months. Although patients receiving bevacizumab-based regimens in the phase I clinical trials had significantly longer PFS than those receiving other anti-angiogenic therapies (p = 0.017), patients treated with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs) had significantly longer OS (12.2 months) than those not treated with VEGFR-TKIs (8.6 months, p = 0.015).

In conclusion, anti-angiogenic therapy is one of the most important strategies for the treatment of HG-EOC, even in those who have already experienced tumor progression. Therefore, eligible patients with HG-EOC should be encouraged to participate in novel phase I studies of anti-angiogenic therapies, even after disease progression.

The rise of genomic profiling in ovarian cancer

INTRODUCTION

Next-generation sequencing and advances in 'omics technology have rapidly increased our understanding of the molecular landscape of epithelial ovarian cancers. Areas covered: Once characterized only by histologic appearance and clinical behavior, we now understand many of the molecular phenotypes that underlie the different ovarian cancer subtypes. While the current approach to treatment involves standard cytotoxic therapies after cytoreductive surgery for all ovarian cancers regardless of histologic or molecular characteristics, focus has shifted beyond a 'one size fits all' approach to ovarian cancer. Expert commentary: Genomic profiling offers potentially 'actionable' opportunities for development of targeted therapies and a more individualized approach to treatment with concomitant improved outcomes and decreased toxicity.

Phase II basket trial of perifosine monotherapy for recurrent gynecologic cancer with or without PIK3CA mutations

Objective Perifosine exhibits anti-tumor activity by inhibiting AKT phosphorylation. The purpose of this phase II basket trial was to evaluate the efficacy and safety of perifosine monotherapy for ovarian, endometrial, and cervical cancers. Methods Recurrent or persistent ovarian, endometrial, or cervical cancer patients were assigned to PIK3CA wild-type or mutant groups. Each patient received 600 mg oral perifosine on day 1 followed by a maintenance dose of 100 mg daily. The primary endpoint was disease control rate; secondary endpoints included response rate, progression-free survival, overall survival, and safety. Immunohistochemical staining and targeted sequencing were used to explore new biomarkers in such patients. Results Sixteen and 5 ovarian, 17 and 7 endometrial, and 18 and 8 cervical cancer patients with PIK3CA wild-type and mutant, respectively, were enrolled. Disease control rates (wild-type/mutant) were 12.5/40.0%, 47.1/14.3%, and 11.1/25.0% in ovarian, endometrial, and cervical cancer, respectively. The most common grade 3/4 toxicities were anemia (22.5%) and anorexia (11.3%). Immunohistochemical staining revealed that the disease control rate in patients with negative phosphatase and tensin homolog (PTEN) expression was 50.0%, and the odds ratio of positive to negative patients was 0.24 in all patients. Conclusions Perifosine monotherapy showed good tolerability but expected efficacy was not achieved. Modest efficacy was demonstrated in ovarian cancer patients with PIK3CA mutations and endometrial cancer patients with PIK3CA wild-type; no difference was observed between PIK3CA wild-type and mutant in cervical cancer. Absence of PTEN expression may be predictive of clinical efficacy with perifosine monotherapy.

Maximising the potential of AKT inhibitors as anti-cancer treatments

PI3K/AKT signalling is commonly disrupted in human cancers, with AKT being a central component of the pathway, influencing multiple processes that are directly involved in tumourigenesis. Targeting AKT is therefore a highly attractive anti-cancer strategy with multiple AKT inhibitors now in various stages of clinical development. In this review, we summarise the role and regulation of AKT signalling in normal cellular physiology. We highlight the mechanisms by which AKT signalling can be hyperactivated in cancers and discuss the past, present and future clinical strategies for AKT inhibition in oncology.

Chemoresistance and targeted therapies in ovarian and endometrial cancers

Gynecological cancers are known for being very aggressive at their advanced stages. Indeed, the survival rate of both ovarian and endometrial cancers is very low when diagnosed lately and the success rate of current chemotherapy regimens is not very efficient. One of the main reasons for this low success rate is the acquired chemoresistance of these cancers during their progression. The mechanisms responsible for this acquired chemoresistance are numerous, including efflux pumps, repair mechanisms, survival pathways (PI3K/AKT, MAPK, EGFR, mTOR, estrogen signaling) and tumor suppressors (P53 and Par-4). To overcome these resistances, a new type of therapy has emerged named targeted therapy. The principle of targeted therapy is simple, taking advantage of changes acquired in malignant cancer cells (receptors, proteins, mechanisms) by using compounds specifically targeting these, thus limiting their action on healthy cells. Targeted therapies are emerging and many clinical trials targeting these pathways, frequently involved in chemoresistance, have been tested on gynecological cancers. Despite some targets being less efficient than expected as mono-therapies, the combination of compounds seems to be the promising avenue. For instance, we demonstrate using ChIP-seq analysis that estrogen downregulate tumor suppressor Par-4 in hormone-dependent cells by directly binding to its DNA regulatory elements and inhibiting estrogen signaling could reinstate Par-4 apoptosis-inducing abilities. This review will focus on the chemoresistance mechanisms and the clinical trials of targeted therapies associated with these, specifically for endometrial and ovarian cancers.

Molecular Characterization of Epithelial Ovarian Cancer: Implications for Diagnosis and Treatment

Epithelial ovarian cancer is a highly heterogeneous disease characterized by multiple histological subtypes. Molecular diversity has been shown to occur within specific histological subtypes of epithelial ovarian cancer, between different tumors of an individual patient, as well as within individual tumors. Recent advances in the molecular characterization of epithelial ovarian cancer tumors have provided the basis for a simplified classification scheme in which these cancers are classified as either type I or type II tumors, and these two categories have implications regarding disease pathogenesis and prognosis. Molecular analyses, primarily based on next-generation sequencing, otherwise known as high-throughput sequencing, are allowing for further refinement of ovarian cancer classification, facilitating the elucidation of the site(s) of precursor lesions of high-grade serous ovarian cancer, and providing insight into the processes of clonal selection and evolution that may be associated with development of chemoresistance. Potential therapeutic targets have been identified from recent molecular profiling studies of these tumors, and the effectiveness and safety of a number of specific targeted therapies have been evaluated or are currently being studied for the treatment of women with this disease.

The rise of genomic profiling in ovarian cancer

INTRODUCTION

Next-generation sequencing and advances in 'omics technology have rapidly increased our understanding of the molecular landscape of epithelial ovarian cancers. Areas covered: Once characterized only by histologic appearance and clinical behavior, we now understand many of the molecular phenotypes that underlie the different ovarian cancer subtypes. While the current approach to treatment involves standard cytotoxic therapies after cytoreductive surgery for all ovarian cancers regardless of histologic or molecular characteristics, focus has shifted beyond a 'one size fits all' approach to ovarian cancer. Expert commentary: Genomic profiling offers potentially 'actionable' opportunities for development of targeted therapies and a more individualized approach to treatment with concomitant improved outcomes and decreased toxicity.

The rise of genomic profiling in ovarian cancer

INTRODUCTION

Next-generation sequencing and advances in 'omics technology have rapidly increased our understanding of the molecular landscape of epithelial ovarian cancers. Areas covered: Once characterized only by histologic appearance and clinical behavior, we now understand many of the molecular phenotypes that underlie the different ovarian cancer subtypes. While the current approach to treatment involves standard cytotoxic therapies after cytoreductive surgery for all ovarian cancers regardless of histologic or molecular characteristics, focus has shifted beyond a 'one size fits all' approach to ovarian cancer. Expert commentary: Genomic profiling offers potentially 'actionable' opportunities for development of targeted therapies and a more individualized approach to treatment with concomitant improved outcomes and decreased toxicity.

Novel mechanisms and approaches to overcome multidrug resistance in the treatment of ovarian cancer

Ovarian cancer remains the leading cause of gynecological cancer-related mortality despite the advances in surgical techniques and chemotherapy drugs over the past three decades. Multidrug resistance (MDR) to chemotherapy is the major cause of treatment failure. Previous research has focused mainly on strategies to reverse MDR by targeting the MDR1 gene encoded P-glycoprotein (Pgp) with small molecular compound inhibitors. However, prior Pgp inhibitors have shown very limited clinical success because these agents have relatively low potency and high toxicity. Therefore, identification of more specific and potent new inhibitors would be useful. In addition, emerging evidence suggests that cancer stem cells (CSCs), deregulated non-coding RNA (ncRNA), autophagy, and tumor heterogeneity also contribute significantly to drug sensitivity/resistance in ovarian cancer. This review summarizes these novel mechanisms of MDR and evaluates several new concepts to overcome MDR in the treatment of ovarian cancer. These new strategies include overcoming MDR with more potent and specific Pgp inhibitors, targeting CSCs and ncRNA, modulating autophagy signaling pathway, and targeting tumor heterogeneity.

Clinical outcome of treatment with serine-threonine kinase inhibitors in recurrent epithelial ovarian cancer: a systematic review of literature

INTRODUCTION

While serine-threonine kinases (STK) are attractive therapeutic targets in epithelial ovarian cancer, clinical outcomes of STK inhibitors in the management of recurrent disease have not been completely described.

AREAS COVERED

A systematic literature review of published clinical studies on STK inhibitors targeting mTOR, MAPK, and aurora kinase pathways in recurrent epithelial ovarian cancer was conducted, revealing 18 clinical trials (497 patients). Pooled analyses were performed to assess treatment response, survival time, and adverse events. Median progression-free survival was 3.4 months in STK inhibitor-based therapy, and the average response rate and clinical benefit rate were 13% and 67%, respectively. Among regimens comprised of only STK inhibitors (11 trials, 299 patients), median progression-free time was 2.7 months, response rate was 10%, and clinical benefit rate was 64%. Compared to single STK inhibitor monotherapy (52.5%), clinical benefit rates significantly improved when STK inhibitors were combined with a cytotoxic agent (71.4%), other class biological agent (74.2%), or an additional STK inhibitor (95.0%) (all, P ≤ 0.002).

EXPERT OPINION

STK inhibitor-based therapy showed modest activity for recurrent epithelial ovarian cancer with reasonable clinical benefit rates, suggesting its potential utility for maintaining disease stability if supported by future studies. Efficacy appears greatly improved in appropriately selected patient populations, especially those with low-grade serous ovarian carcinoma, platinum-sensitive disease, cancers with somatic RAS or BRAF mutations, and when used in a combination regimen with a cytotoxic or biological agent.

Somatic mutations in breast and serous ovarian cancer young patients: a systematic review and meta-analysis

OBJECTIVE

our aim was to evaluate whether somatic mutations in five genes were associated with an early age at presentation of breast cancer (BC) or serous ovarian cancer (SOC).

METHODS

COSMIC database was searched for the five most frequent somatic mutations in BC and SOC. A systematic review of PubMed was performed. Young age for BC and SOC patients was set at ≤ 35 and ≤ 40 years, respectively. Age groups were also classified in < 30 years and every 10 years thereafter.

RESULTS

twenty six (1,980 patients, 111 younger) and 16 studies (598, 41 younger), were analyzed for BC and SOC, respectively. In BC, PIK3CA wild type tumor was associated with early onset, not confirmed in binary regression with estrogen receptor (ER) status. In HER2-negative tumors, there was increased frequency of PIK3CA somatic mutation in older age groups; in ER-positive tumors, there was a trend towards an increased frequency of PIK3CA somatic mutation in older age groups. TP53 somatic mutation was described in 20% of tumors from both younger and older patients; PTEN, CDH1 and GATA3 somatic mutation was investigated only in 16 patients and PTEN mutation was detected in one of them. In SOC, TP53 somatic mutation was rather common, detected in more than 50% of tumors, however, more frequently in older patients.

CONCLUSION

frequency of somatic mutations in specific genes was not associated with early-onset breast cancer. Although very common in patients with serous ovarian cancer diagnosed at all ages, TP53 mutation was more frequently detected in older women.

Genetic and epigenetic heterogeneity of epithelial ovarian cancer and the clinical implications for molecular targeted therapy

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and tumoural heterogeneity (TH) has been blamed for treatment failure. The genomic and epigenomic atlas of EOC varies significantly with tumour histotype, grade, stage, sensitivity to chemotherapy and prognosis. Rapidly accumulating knowledge about the genetic and epigenetic events that control TH in EOC has facilitated the development of molecular-targeted therapy. Poly (ADP-ribose) polymerase (PARP) inhibitors, designed to target homologous recombination, are poised to change how breast cancer susceptibility gene (BRCA)-related ovarian cancer is treated. Epigenetic treatment regimens being tested in clinical or preclinical studies could provide promising novel treatment approaches and hope for improving patient survival.

An overview of tyrosine kinase inhibitors for the treatment of epithelial ovarian cancer

INTRODUCTION

Epithelial ovarian cancer (EOC) is the most lethal gynecologic malignancy and the fifth most common cause of cancer-related deaths in women. Initial treatment with surgery and chemotherapy has improved survival significantly. However, the disease progresses or recurs in most patients. Thus, there is an urgent need to develop more effective treatment strategies.

AREAS COVERED

This article provides an overview of tyrosine kinase inhibitors (TKIs) for the treatment of EOC, which is based on English peer-reviewed articles on MEDLINE and related abstracts presented at major conferences. The authors highlight the data from the published clinical trials in EOC patients who were treated with TKIs or TKI-based regimens.

EXPERT OPINION

EOC is responsive to most chemotherapeutic drugs and/or biological agents and represents an ideal disease model for investigating novel anti-cancer agents. Numerous small-molecule TKIs targeting the VEGFR, PARP, PI3K-AKT-mTOR, MAPK, Src, PKC, Wee1 and HER1/2 signaling pathways are currently being tested in clinical trials. Research is needed for devising regimens combining TKIs with other agents in an optimal timing schedule and for identifying potential biomarkers predictive of response and survival.

Emerging strategies for targeting PI3K in gynecologic cancer

Ovarian, endometrial and cervical cancers are the most prevalent gynecologic cancers in the United States and account for significant mortality. Translational research into these cancers has highlighted the distinctive molecular and genomic profiles of these cancers finding that, even within a disease site, the landscapes and drivers of neoplasia are distinctive. Despite this molecular diversity, activation of the phosphatidylinositol-3-kinase (PI3K) pathway appears to be conserved in subsets of these tumors, suggesting that strategies that antagonize mediators in this signaling cascade could offer anti-tumor efficacy. Extensive pre-clinical and clinical data have demonstrated that single agent targeted therapies lead to modest single agent activity of generally limited duration, even in the setting of innate PI3K pathway activation via mutation or amplification. These findings in the laboratory and clinic have prompted investigations into resistance pathways following PI3K pathway inhibition in order to understand escape pathways and restore tumor cell sensitivity. A next generation of clinical trial investigations will focus on novel combinations in order to define how these important therapeutics can be used in the clinic. This review will present preclinical data that supports the role of the PI3K pathway in ovarian, endometrial and cervical cancers, in addition to discussing the reported clinical trial experience with PI3K pathway inhibition. A specific focus will be on the rationale behind ongoing clinical trials utilizing novel agents in concert with PI3K pathway inhibitors to reverse resistance in populations with and without gain of function alterations in this oncogenic signaling cascade.

The PI3K/AKT/mTOR pathway as a therapeutic target in ovarian cancer

The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) pathway plays a critical role in the malignant transformation of human tumors and their subsequent growth, proliferation, and metastasis. Preclinical investigations have suggested that the PI3K/AKT/mTOR pathway is frequently activated in ovarian cancer, especially in clear cell carcinoma and endometrioid adenocarcinoma. Thus, this pathway is regarded as an attractive candidate for therapeutic interventions, and inhibitors targeting different components of this pathway are in various stages of clinical development. Here, we highlight the recent progress that has been made in our understanding of the PI3K/AKT/mTOR pathway and discuss the potential of therapeutic agents that target this pathway as treatments for ovarian cancer and the obstacles to their development.

Anti-tumor activities of lipids and lipid analogues and their development as potential anticancer drugs

Lipids have the potential for development as anticancer agents. Endogenous membrane lipids, such as ceramides and certain saturated fatty acids, have been found to modulate the viability of tumor cells. In addition, many tumors over-express cyclooxygenase, lipoxygenase or cytochrome P450 enzymes that mediate the biotransformation of ω-6 polyunsaturated fatty acids (PUFAs) to potent eicosanoid regulators of tumor cell proliferation and cell death. In contrast, several analogous products from the biotransformation of ω-3 PUFAs impair particular tumorigenic pathways. For example, the ω-3 17,18-epoxide of eicosapentaenoic acid activates anti-proliferative and proapoptotic signaling cascades in tumor cells and the lipoxygenase-derived resolvins are effective inhibitors of inflammatory pathways that may drive tumor expansion. However, the development of potential anti-cancer drugs based on these molecules is complex, with in vivo stability a major issue. Nevertheless, recent successes with the antitumor alkyl phospholipids, which are synthetic analogues of naturally-occurring membrane phospholipid esters, have provided the impetus for development of further molecules. The alkyl phospholipids have been tested against a range of cancers and show considerable activity against skin cancers and certain leukemias. Very recently, it has been shown that combination strategies, in which alkyl phospholipids are used in conjunction with established anticancer agents, are promising new therapeutic approaches. In future, the evaluation of new lipid-based molecules in single-agent and combination treatments may also be assessed. This could provide a range of important treatment options in the management of advanced and metastatic cancer.

The PI3K/Akt/mTOR pathway in ovarian cancer: therapeutic opportunities and challenges

The phosphatidylinositol 3 kinase (PI3K) pathway is frequently altered in cancer, including ovarian cancer (OC). Unfortunately, despite a sound biological rationale and encouraging activity in preclinical models, trials of first-generation inhibitors of mammalian target of rapamycin (mTOR) in OC have demonstrated negative results. The lack of patient selection as well as resistance to selective mTOR complex-1 (mTORC1) inhibitors could explain the disappointing results thus far. Nonetheless, a number of novel agents are being investigated, including dual mTORC1/mTORC2, Akt, and PI3K inhibitors. Although it is likely that inhibition of the PI3K/Akt/mTOR pathway may have little effect in unselected OC patients, certain histological types, such as clear cell or endometrioid OC with frequent phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit alpha (PIK3CA) and/or phosphatase and tensin homolog (PTEN) alterations, may be particularly suited to this approach. Given the complexity and redundancy of the PI3K signaling network, PI3K pathway inhibition may be most useful in combination with either chemotherapy or other targeted therapies, such as MEK inhibitors, anti-angiogenic therapy, and hormonal therapy, in appropriately selected OC patients. Here, we discuss the relevance of the PI3K pathway in OC and provide an up-to-date review of clinical trials of novel PI3K inhibitors alone or in combination with cytotoxics and novel therapies in OC. In addition, the challenges of drug resistance and predictive biomarkers are addressed.

The PI3K/Akt/mTOR pathway in ovarian cancer: therapeutic opportunities and challenges

The phosphatidylinositol 3 kinase (PI3K) pathway is frequently altered in cancer, including ovarian cancer (OC). Unfortunately, despite a sound biological rationale and encouraging activity in preclinical models, trials of first-generation inhibitors of mammalian target of rapamycin (mTOR) in OC have demonstrated negative results. The lack of patient selection as well as resistance to selective mTOR complex-1 (mTORC1) inhibitors could explain the disappointing results thus far. Nonetheless, a number of novel agents are being investigated, including dual mTORC1/mTORC2, Akt, and PI3K inhibitors. Although it is likely that inhibition of the PI3K/Akt/mTOR pathway may have little effect in unselected OC patients, certain histological types, such as clear cell or endometrioid OC with frequent phosphatidylinositol-4,5-biphosphate 3-kinase, catalytic subunit alpha (PIK3CA) and/or phosphatase and tensin homolog (PTEN) alterations, may be particularly suited to this approach. Given the complexity and redundancy of the PI3K signaling network, PI3K pathway inhibition may be most useful in combination with either chemotherapy or other targeted therapies, such as MEK inhibitors, anti-angiogenic therapy, and hormonal therapy, in appropriately selected OC patients. Here, we discuss the relevance of the PI3K pathway in OC and provide an up-to-date review of clinical trials of novel PI3K inhibitors alone or in combination with cytotoxics and novel therapies in OC. In addition, the challenges of drug resistance and predictive biomarkers are addressed.

Preclinical Efficacy for AKT Targeting in Clear Cell Carcinoma of the Ovary

The aim of this study was to determine the role of AKT as a therapeutic target in ovarian clear cell carcinoma (CCC), an aggressive, chemoresistant histologic subtype of ovarian cancer. AKT activation was assessed by immunohistochemistry (IHC) using human tissue microarrays of primary ovarian cancers, composed of both CCC and serous adenocarcinoma (SAC). The growth-inhibitory effect of AKT-specific targeting by the small-molecule inhibitor, perifosine, was examined using ovarian CCC cell lines in vitro and in vivo. Finally, the activity of perifosine was examined using in CCC-derived tumors that had acquired resistance to anti-VEGF or chemotherapeutics such as bevacizumab or cisplatin, respectively. Interestingly, AKT was frequently activated both in early-stage and advanced-stage CCCs. Treatment of CCC cells with perifosine attenuated the activity of AKT-mTORC1 signaling, inhibited proliferation, and induced apoptosis. The effect of perifosine was more profound under conditions of high AKT activity compared with low AKT activity. Increased AKT activation and enhanced sensitivity to perifosine were observed in the context of cisplatin-resistant CCC. Treatment with perifosine concurrently with cisplatin significantly enhanced the antitumor effect of cisplatin. Moreover, perifosine showed significant antitumor activity in CCC-derived tumors that had acquired resistance to bevacizumab or cisplatin. Collectively, these data reveal that AKT is frequently activated in ovarian CCCs and is a promising therapeutic target in aggressive forms of ovarian cancer.

IMPLICATIONS

AKT-targeted therapy has value in a first-line setting as well as a second-line treatment for recurrent disease developing after platinum-based chemotherapy or bevacizumab treatment.

Genomic analyses of gynaecologic carcinosarcomas reveal frequent mutations in chromatin remodelling genes

Malignant mixed Müllerian tumours, also known as carcinosarcomas, are rare tumours of gynaecological origin. Here we perform whole-exome analyses of 22 tumours using massively parallel sequencing to determine the mutational landscape of this tumour type. On average, we identify 43 mutations per tumour, excluding four cases with a mutator phenotype that harboured inactivating mutations in mismatch repair genes. In addition to mutations in TP53 and KRAS, we identify genetic alterations in chromatin remodelling genes, ARID1A and ARID1B, in histone methyltransferase MLL3, in histone deacetylase modifier SPOP and in chromatin assembly factor BAZ1A, in nearly two thirds of cases. Alterations in genes with potential clinical utility are observed in more than three quarters of the cases and included members of the PI3-kinase and homologous DNA repair pathways. These findings highlight the importance of the dysregulation of chromatin remodelling in carcinosarcoma tumorigenesis and suggest new avenues for personalized therapy.

Malignant mixed Müllerian tumours are a rare and aggressive gynaecological cancer with poor 5-year survival rates. Here, the authors characterize the mutational landscape of carcinosarcomas and highlight the role of chromatin remodelling dysregulation in carcinosarcoma tumorigenesis.

In vitro synergistic action of geldanamycin- and docetaxel-containing HPMA copolymer-RGDfK conjugates against ovarian cancer

HPMA copolymer-RGDfK (HPMA-RGDfK) conjugates bearing either aminohexylgeldanamycin (AHGDM) or docetaxel (DOC) were synthesized and characterized. In vitro stability and binding were evaluated. Cytotoxicity toward ovarian cancer cells was evaluated and the ability of the conjugates to induce cell death was assessed by combination index analysis. Conjugates bearing AHGDM were more stable and exhibited slower drug release than those bearing DOC. Both conjugates demonstrated the ability to bind to avb3 integrins. In combination, HPMA-RGDfK conjugates demonstrated marked synergism as compared to their non-targeted counterparts and free drug controls. HPMA-RGDfK conjugates bearing AHGDM and DOC induce synergistic cytotoxicity in vitro, suggesting their potential as a promising combination therapy.

Current clinical regulation of PI3K/PTEN/Akt/mTOR signalling in treatment of human cancer

PURPOSE

PTEN is an essential tumour suppressor gene which encodes a phosphatase protein that antagonises the PI3K/Akt/mTOR antiapoptotic pathway. Impairment of this tumour suppressor pathway potentially becomes a causal factor for development of malignancies. This review aims to assess current understanding of mechanisms of dysfunction involving the PI3K/PTEN/Akt/mTOR pathway linked to tumorigenesis and evaluate the evidence for targeted therapy directed at this signalling axis.

METHODS

Relevant articles in scientific databases were identified using a combination of search terms, including "malignancies", "targeted therapy", "PTEN", and "combination therapy". These databases included Medline, Embase, Cochrane Review, Pubmed, and Scopus.

RESULTS

PI3K/PTEN expression is frequently deregulated in a majority of malignancies through genetic, epigenetic, and post-transcriptional modifications. This contributes to the upregulation of the PI3K/Akt/mTOR pathway which has been the focus of intense clinical studies. Targeted agents aimed at this pathway offer a novel treatment approach in a variety of haematologic malignancies and solid tumours. Compared to single-agent use, greater response rates were obtained in combination regimens, supporting further investigation of suitable drug combinations in a broad spectrum of malignancies.

CONCLUSION

Activation of the PI3K/PTEN/Akt/mTOR pathway is implicated both in the pathogenesis of malignancies and development of resistance to anticancer therapies. Therefore, PI3K/Akt/mTOR inhibitors are a promising therapeutic option, in association with systemic cytotoxic and biological therapies, to enable sustained clinical outcomes in cancer treatment. Therapeutic strategies could be tailored according to appropriate biomarkers and patient-specific mutation profiles to maximise benefit of combination therapies.

PI3K/AKT/mTOR signaling pathway as a therapeutic target for ovarian cancer

BACKGROUND

Ovarian cancer is one of the major causes of death in women worldwide. Despite improvements in conventional treatment approaches, such as surgery and chemotherapy, a majority of patients with advanced ovarian cancer experience relapse and eventually succumb to the disease; the outcome of patients remains poor. Hence, new therapeutic strategies are urgently required. The phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) is activated in approximately 70 % of ovarian cancers, resulting in hyperactive signaling cascades that relate to cellular growth, proliferation, survival, metabolism, and angiogenesis. Consistent with this, a number of clinical studies are focusing on PI3K pathway as an attractive target in the treatment of ovarian cancer. In this review, we present an overview of PI3K pathway as well as its pathological aberrations reported in ovarian cancer. We also discuss inhibitors of PI3K pathway that are currently under clinical investigations and the challenges these inhibitors face in future clinical utility.

METHODS

PubMed was searched for articles of relevance to ovarian cancer and the PI3K pathway. In addition, the ClinicalTrials.gov was also scanned for data on novel therapeutic inhibitors targeting the PI3K pathway.

RESULTS

Genetic aberrations at different levels of PI3K pathway are frequently observed in ovarian cancer, resulting in hyperactivation of this pathway. The alterations of this pathway make the PI3K pathway an attractive therapeutic target in ovarian cancer. Currently, several inhibitors of PI3K pathway, such as PI3K/AKT inhibitors, rapamycin analogs for mTOR inhibition, and dual PI3K/mTOR inhibitors are in clinical testing in patients with ovarian cancer.

CONCLUSIONS

PI3K pathway inhibitors have shown great promise in the treatment of ovarian cancer. However, further researches on selection patients that respond to PI3K inhibitors and exploration of effective combinatorial therapies are required to improve the management of ovarian cancer.

Symptom Burden and Outcomes of Patients With Platinum Resistant/Refractory Recurrent Ovarian Cancer: A Reality Check

Background

The aim of chemotherapy in patients with platinum resistant ovarian cancer is palliation. Patients’ experience of symptoms is not well documented, and the impact of treatment on symptoms has not been evaluated in clinical trials. We report symptom burden and treatment outcomes from stage 1 of the Gynecological Cancer Intergroup (GCIG) Symptom Benefit Study.

Methods

One hundred twenty-six patients receiving palliative chemotherapy completed 5 validated health-related quality-of-life questionnaires before starting treatment and before each cycle. They also reported their expected and perceived benefits from treatment. Physicians documented the reasons for treatment and adverse events including symptoms at baseline and estimated the number of cycles of treatment that patients would receive.

Results

Palliation was the major reason for chemotherapy. At baseline, all patients were symptomatic (almost 70% had ≥9 symptoms). Patients had high expectation of benefit from treatment. Only 41% of patients received the predicted number of cycles with most stopping early (≤2 cycles) due to progression, death, or adverse effects. Treatment was associated with significant toxicity, with discordance between patient report and physician grading. Although RECIST response rates were low (8.5%), 40% of the patients were reported to have had a clinical benefit and almost 50% of symptomatic patients also reported symptom improvement.

Conclusions

Patients had a complex array of symptoms and significant symptom burden, which was commonly the reason for treatment. Although chemotherapy improved symptoms in about half of the patients, many did not benefit and progressed rapidly. Our findings support research into the use of patient reported outcome measures to document symptoms, adverse events, and subjective benefit, both in clinical trials and in clinical practice, in this patient population. Our findings highlight the need to develop prognostic models to better select patients for treatment, and this is an aim of stage 2 of the GCIG Symptom Benefit Study.