Safety and pharmacokinetics of paclitaxel and the oral mTOR inhibitor everolimus in advanced solid tumours

Microscopy-based phenotypic monitoring of MDA-MB-231 spheroids allows the evaluation of phenotype-directed therapy

Breast cancer (BC) is the most commonly diagnosed cancer among women. Prognosis has improved over the years, to a large extent, owing to personalized therapy informed by molecular profiling of hormone receptors. However, there is a need for new therapeutic approaches for a subgroup of BCs lacking molecular markers, the Triple Negative Breast Cancer (TNBC) subgroup. TNBC is the most aggressive type of BC, lacks an effective standard of care, shows high levels of resistance and relapse is often inevitable. High resistance to therapy has been hypothesized to be associated with high intratumoral phenotypic heterogeneity. To characterize and treat this phenotypic heterogeneity, we optimized a whole-mount staining and image analysis protocol for three-dimensions (3D) spheroids. Applying this protocol to TNBC spheroids located in the outer region of the spheroid the cells with selected phenotypes: dividing, migrating, and high mitochondrial mass phenotypes. To evaluate the relevance of phenotype-based targeting these cell populations were targeted with Paclitaxel, Trametinib, and Everolimus, respectively, in a dose-dependent manner. Single agents cannot specifically target all phenotypes at the same time. Therefore, we combined drugs that should target independent phenotype. With this rationale we observed that combining Trametinib and Everolimus achieves the highest cytotoxicity at lower doses from all the tested combinations. These findings suggest a rational approach to design treatments can be evaluated in spheroids prior to pre-clinical models and potentially reduce adverse effects.

OUP accepted manuscript

Background

Treatment options have been historically limited for cisplatin-ineligible patients with advanced urothelial carcinoma (UC). Given the need for alternatives to platinum-based chemotherapy, including non-chemotherapy regimens for patients with both impaired renal function and borderline functional status, in 2010 (prior to the immune checkpoint blockade era in metastatic UC), we initiated a phase II trial to test the activity of everolimus or everolimus plus paclitaxel in the cisplatin-ineligible setting.

Methods

This was an open-label phase II trial conducted within the US-based Hoosier Cancer Research Network (ClinicalTrials.gov number: NCT01215136). Patients who were cisplatin-ineligible with previously untreated advanced UC were enrolled. Patients with both impaired renal function and poor performance status were enrolled into cohort 1; patients with either were enrolled into cohort 2. Patients received everolimus 10 mg daily alone (cohort 1) or with paclitaxel 80 mg/m² on days 1, 8, and 15 of each 28-day cycle (cohort 2). The primary outcome was clinical benefit at 4 months. Secondary outcomes were adverse events, progression-free survival (PFS), and 1-year overall survival (OS). Exploratory endpoints included genomic correlates of outcomes. The trial was not designed for comparison between cohorts.

Results

A total of 36 patients were enrolled from 2010 to 2018 (cohort 1, N = 7; cohort 2, N = 29); the trial was terminated due to slow accrual. Clinical benefit at 4 months was attained by 0 (0%, 95% confidence interval [CI] 0-41.0%) patients in cohort 1 and 11 patients (37.9%, 95% CI 20.7-57.7%) in cohort 2. Median PFS was 2.33 (95% CI 1.81-Inf) months in cohort 1 and 5.85 (95% CI 2.99-8.61) months in cohort 2. Treatment was discontinued due to adverse events for 2 patients (29%) in cohort 1 and 11 patients (38%) in cohort 2. Molecular alterations in microtubule associated genes may be associated with treatment benefit but this requires further testing.

Conclusion

Everolimus plus paclitaxel demonstrates clinical activity in cisplatin-ineligible patients with metastatic UC, although the specific contribution of everolimus cannot be delineated. Patients with both impaired renal function and borderline functional status may be difficult to enroll to prospective trials. (ClinicalTrials.gov Identifier NCT01215136).

A novel role for α-viniferin in suppressing angiogenesis by blocking the VEGFR-2/p70S6K signaling pathway

Angiogenesis plays important roles in pathological conditions such as cancer and inflammation as well as normal tissue development and homeostasis. Here, we investigated the effects and molecular mechanisms of α-viniferin, an oligostilbene isolated from Caragana sinica, on human umbilical vein endothelial cell responses in vitro and angiogenic sprouting in aortic rings ex vivo. α-viniferin treatment inhibited mitogen-induced HUVEC proliferation by retinoblastoma protein hypophosphorylation. In addition, α-viniferin suppressed mitogen-induced HUVEC adhesion, migration, invasion, and microvessel outgrowth. These anti-angiogenic activities of α-viniferin might be mediated through downregulation of cell cycle-related proteins, vascular endothelial growth factor receptor-2 (VEGFR-2), and matrix metalloproteinase-2. Furthermore, inactivation of VEGFR-2/p70 ribosomal S6 kinase signaling pathway was found to be involved in α-viniferin-mediated modulation of endothelial cell responses. Our results demonstrate the pharmacological functions and molecular mechanisms of α-viniferin in regulating angiogenesis, suggesting the therapeutic potential of α-viniferin to treat and prevent various angiogenesis-related diseases.

Synergistic drug combinations for a precision medicine approach to interstitial glioblastoma therapy

Glioblastoma (GBM) is a highly aggressive and heterogeneous form of brain cancer. Genotypic and phenotypic heterogeneity drives drug resistance and tumor recurrence. Combination chemotherapy could overcome drug resistance; however, GBM's location behind the blood-brain barrier severely limits chemotherapeutic options. Interstitial therapy, delivery of chemotherapy locally to the tumor site, via a biodegradable polymer implant can overcome the blood-brain barrier and increase the range of drugs available for therapy. Ideal drug candidates for interstitial therapy are those that are potent against GBM and work in combination with both standard-of-care therapy and new precision medicine targets. Herein we evaluated paclitaxel for interstitial therapy, investigating the effect of combination with both temozolomide, a clinical standard-of-care chemotherapy for GBM, and everolimus, a mammalian target of rapamycin (mTOR) inhibitor that modulates aberrant signaling present in >80% of GBM patients. Tested against a panel of GBM cell lines in vitro, paclitaxel was found to be effective at nanomolar concentrations, complement therapy with temozolomide, and synergize strongly with everolimus. The strong synergism seen with paclitaxel and everolimus was then explored in vivo. Paclitaxel and everolimus were separately formulated into fibrous scaffolds composed of acetalated dextran, a biodegradable polymer with tunable degradation rates, for implantation in the brain. Acetalated dextran degradation rates were tailored to attain matching release kinetics (~3% per day) of both paclitaxel and everolimus to maintain a fixed combination ratio of the two drugs. Combination interstitial therapy of both paclitaxel and everolimus significantly reduced GBM growth and improved progression free survival in two clinically relevant orthotopic models of GBM resection and recurrence. This work illustrates the advantages of synchronized interstitial therapy of paclitaxel and everolimus for post-surgical tumor control of GBM.

Stomatitis And Everolimus: A Review Of Current Literature On 8,201 Patients

Background

Oral toxicities, such as mucositis and stomatitis, are some of the most significant and unavoidable side effects associated with anticancer therapies. In past decades, research has focused on newer targeted agents with the aim of decreasing the rates of side effects on healthy cells. Unfortunately, even targeted anticancer therapies show significant rates of toxicity on healthy tissue. mTOR inhibitors display some adverse events, such as hyperglycemia, hyperlipidemia, hypophosphatemia, hematologic toxicities, and mucocutaneous eruption, but the most important are still stomatitis and skin rash, which are often dose-limiting side effects.

Aim

This review was performed to answer the question “What is the incidence of stomatitis in patients treated with everolimus?”

Methods

We conducted a systematic search on the PubMed and Medline online databases using a combination of MESH terms and free text: “everolimus” (MESH) AND “side effects” OR “toxicities” OR “adverse events”. Only studies fulfilling the following inclusion criteria were considered eligible for inclusion in this study: performed on human subjects, reporting on the use of everolimus (even if in combination with other drugs or ionizing radiation), written in the English language, and reporting the incidence of side effects.

Results

The analysis of literature revealed that the overall incidence of stomatitis after treatment with everolimus was 42.6% (3,493) and that of stomatitis grade G1/2 84.02% (2,935), while G3/4 was 15.97% (558).

Conclusion

Results of the analysis showed that the incidence of stomatitis of grade 1 or 2 is higher than grade 3 or 4. However, it must be taken into account that it is not possible to say if side effects are entirely due to everolimus therapy or combinations with other drugs.

In Vivo Evaluation of Dual-Targeted Nanoparticles Encapsulating Paclitaxel and Everolimus

A synergistic combination of paclitaxel (PTX) and everolimus (EVER) can allow for lower drug doses, reducing the toxicities associated with PTX, while maintaining therapeutic efficacy. Polymeric nanoparticles (NPs) of high stability provide opportunities to modify the toxicity profile of the drugs by ensuring their delivery to tumor at the synergistic ratio while limiting systemic drug exposure and the toxicities that result. The current study goal is to study the in vivo fate of human epidermal factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) dual-targeted PTX+EVER-loaded NPs (Dual-NPs) in an MDA-MB-231-H2N BC tumor-bearing mouse model. The pharmacokinetic parameters, plasma area under the curve (AUC) and half-life (t1/2), were found to be 20-fold and 3 to 4-fold higher, respectively, for the drugs when administered in the Dual-NPs in comparison to the free-drug combination (i.e., PTX+EVER) at an equivalent dose of PTX. While maintaining anti-tumor efficacy, the levels of body weight loss were significantly lower (p < 0.0001) and the overall degree of neurotoxicity was reduced with Dual-NP treatment in comparison to the free-drug combination when administered at an equivalent dose of PTX. This study suggests that Dual-NPs present a promising platform for the delivery of the PTX and EVER combination with the potential to reduce severe PTX-induced toxicities and in turn, improve quality of life for patients with BC.

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.

Pharmacokinetics and safety of olaparib tablets as monotherapy and in combination with paclitaxel: results of a Phase I study in Chinese patients with advanced solid tumours

PURPOSE

Chinese patients have been enrolled in multiple Phase III trials of the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib (Lynparza); however, the pharmacokinetic (PK) profile of olaparib has not been investigated in this population. This two-part, open-label Phase I study was, therefore, carried out to determine the PK and safety profile of olaparib (tablet formulation) in Chinese patients with advanced solid tumours as monotherapy and in combination with paclitaxel (NCT02430311).

METHODS

The PK profile of olaparib 300 mg (twice daily [bid]; Cohort 1) as monotherapy after a single dose and at steady state, and 100 mg (bid; Cohort 2) as monotherapy (single dose and at steady state) and in combination (at steady state) with weekly paclitaxel (80 mg/m²) was assessed during Part A. Patients could continue to receive treatment (monotherapy, Cohort 1; combination therapy, Cohort 2) in Part B, which assessed safety and tolerability.

RESULTS

Twenty and 16 patients were enrolled into Cohorts 1 and 2, respectively. Steady-state olaparib exposure increased slightly less than proportionally with increasing monotherapy dose and inter-patient variability was high. A statistically significant decrease in olaparib exposure was seen when given in combination with paclitaxel. Discontinuation due to adverse events (AEs) was rare and haematological AEs were more common in patients receiving combination treatment.

CONCLUSIONS

The PK and safety profile of olaparib monotherapy in Chinese patients is consistent with that seen previously in Western and Japanese patients, and the recommended Phase III monotherapy tablet dose (300 mg bid) is suitable for use in this population.

Oral stomatitis and mTOR inhibitors: A review of current evidence in 20,915 patients

BACKGROUND

Traditional treatment of malignancies with chemotherapeutic agents is often affected by the damage inflicted on non-cancerous cells. Toxicities of the oral cavity, such as mucositis and stomatitis, are some of the most significant and unavoidable toxicities associated with anti-cancer therapies. For such reason, in the last decades, newer targeted agents have been developed aiming to decrease the rates of side effects on healthy cells. Unfortunately, targeted anti-cancer therapies also showed significant rate of toxicity on healthy tissues. mTOR inhibitors showed some adverse events, such as hyperglycemia, hyperlipidemia, hypophosphatemia, hematologic toxicities, and mucocutaneous eruption, but the most important are still stomatitis and skin rash, often reported as dose-limiting side effects.

PATIENTS AND METHODS

A search of the literature was performed by authors on the PubMed online database using the following key words: "sirolimus" OR "everolimus" OR "temsirolimus" OR "deforolimus" OR "ridaforolimus" combined with the Boolean operator AND with the terms: "stomatitis" OR "mucositis" OR "oral pain." Titles and abstracts of 382 potentially relevant studies were screened; of these, 114 studies were excluded because they did not report the inclusion criteria. In the second round, 268 studies were read full-text, but only 135 reported the inclusion criteria and were included for data extraction. Of the included studies, 95 referred to everolimus use, 16 to ridaforolimus, and 26 to temsirolimus (two studies referred to both everolimus and temsirolimus).

RESULTS

The incidence rate of stomatitis according to the agent used was 25.07% (3,959/15,787) for everolimus, 27.02% (724/2,679) for temsirolimus, and 54.76% (598/1,092) for ridaforolimus. All the three agents analyzed showed high rates of low-grade stomatitis (G1-G2), while the onset of severe stomatitis (G3-G4) was rare.

CONCLUSIONS

Analysis of the reports with patients treated with everolimus, temsirolimus, and ridaforolimus showed a clear prevalence of stomatitis grade 1 or 2. These data differ from that of patients treated with conventional chemotherapy in which mucositis is predominantly of grade 3 or 4.

Codelivery of Paclitaxel and Everolimus at the Optimal Synergistic Ratio: A Promising Solution for the Treatment of Breast Cancer

Clinical studies examining the combination of paclitaxel (PTX) and everolimus (EVER), an mTOR inhibitor, have failed to result in significant improvements in efficacy and toxicity in patients with breast cancer (BC), relative to treatment with PTX alone. These disappointing clinical trial results have been attributed to poorly designed preclinical studies using the combination of PTX and EVER as well as the significantly different pharmacokinetic profiles of the two drugs. In the current work, the potential synergy between PTX and EVER was examined in a panel of six BC cell lines that differ in terms of their molecular subtype and drug sensitivity. Polymeric nanoparticles (NPs) were used to encapsulate PTX and EVER at an optimal synergistic ratio to achieve specific, colocalized delivery of the combination therapy in BC cell lines. Combinations of PTX and EVER (especially at relatively high doses of EVER) resulted in pronounced synergy in all BC cell lines evaluated. The optimal molar ratio of PTX:EVER was determined to be 1:0.5. The combination was delivered to BC cells at the synergistic ratio via encapsulation within polymeric NPs formed from the poly(ethylene glycol)- b-poly(lactide- co-glycolide) (PEG- b-PLGA) copolymer. The NPs had an average diameter of less than 100 nm and were capable of in vitro retention of the encapsulated PTX and EVER at the optimal synergistic molar ratio for over 7 days. Cytotoxicity data demonstrated that PTX+EVER-loaded NPs were significantly less cytotoxic than the free drug combination in MCF-7 and SKBR3 BC cell lines following 72 h, suggesting that PTX+EVER-loaded NPs remain stable and retain the drug combination loaded within the core after 72 h. The uptake of FITC-labeled NPs in SKBR3 cells was evaluated by flow cytometry, with approximately 41% of cells demonstrating detectable fluorescence after 24 h of exposure. The thorough and systematic approach used in this study to determine and evaluate a synergistic PTX:EVER ratio in conjunction with a potentially promising delivery vector for the drug combination could offer a future clinical benefit for patients with BC.

Synergistic antitumour effects of rapamycin and oncolytic reovirus

There are currently numerous oncolytic viruses undergoing clinical trial evaluation in cancer patients and one agent, Talimogene laherparepvec, has been approved for the treatment of malignant melanoma. This progress highlights the huge clinical potential of this treatment modality, and the focus is now combining these agents with conventional anticancer treatments or agents that enhance viral replication, and thereby oncolysis, in the tumour microenvironment. We evaluated the combination of reovirus with rapamycin in B16F10 cell, a murine model of malignant melanoma, based on potential mechanisms by which mTOR inhibitors might enhance viral oncolysis. Rapamycin was not immunomodulatory in that it had no effect on the generation of an antireovirus-neutralising antibody response in C57/black 6 mice. The cell cycle effects of reovirus (increase G0/G1 fraction) were unaffected by concomitant or sequential exposure of rapamycin. However, rapamycin attenuated viral replication if given prior or concomitantly with reovirus and similarly reduced reovirus-induced apoptotic cell death Annexin V/PI and caspase 3/7 activation studies. We found clear evidence of synergistic antitumour effects of the combination both in vitro and in vivo, which was sequence dependent only in the in vitro setting. In conclusion, we have demonstrated synergistic antitumour efficacy of reovirus and rapamycin combination.

Phase Ib Pilot Study to Evaluate Reparixin in Combination with Weekly Paclitaxel in Patients with HER-2-Negative Metastatic Breast Cancer

Purpose: Chemokine receptor 1 (CXCR1) is recognized as an actionable receptor selectively expressed by breast cancer stem cells (BCSCs). Reparixin is an investigational allosteric inhibitor of chemokine receptors 1 and 2 (CXCR1/2), and demonstrates activity against BCSCs in human breast cancer xenografts. This phase Ib clinical trial examined dose, safety, and pharmacokinetics of paclitaxel plus reparixin therapy, and explored effects of reparixin on BCSCs in patients with metastatic breast cancer (MBC) (trial registration ID: NCT02001974).Experimental Design: Eligible patients had MBC and were candidates for paclitaxel therapy. Study treatment included a 3-day run-in with reparixin oral tablets three times a day, followed by paclitaxel 80 mg/m2/week (days 1, 8, and 15 for 28-day cycle) + reparixin tablets three times a day for 21/28 days; three dose cohorts were examined in a 3+3 dose escalation schema. Additional patients were recruited into an expansion cohort at the recommended phase II dose to further explore pharmacokinetics, safety, and biological effects of the combination therapy.Results: There were neither G4-5 adverse events nor serious adverse events related to study therapy and no interactions between reparixin and paclitaxel to influence their respective pharmacokinetic profiles. A 30% response rate was recorded, with durable responses >12 months in two patients. Exploratory biomarker analysis was inconclusive for therapy effect on BCSCs.Conclusions: Weekly paclitaxel plus reparixin in MBC appeared to be safe and tolerable, with demonstrated responses in the enrolled population. Dose level 3, 1200 mg orally three times a day, was selected for further study in a randomized phase II trial (NCT02370238). Clin Cancer Res; 23(18); 5358-65. ©2017 AACR.

A Review of mTOR Pathway Inhibitors in Gynecologic Cancer

The treatment of advanced gynecologic cancers remains palliative in most of cases. Although systemic treatment has entered into the era of targeted drugs the antitumor efficacies of current therapies are still limited. In this context there is a great need for more active treatment and rationally designed targeted therapies. The PI3K/AKT/mTOR is a signaling pathway in mammal cells that coordinates important cell activities. It has a critical function in the survival, growth, and proliferation of malignant cells and was object of important research in the last two decades. The mTOR pathway emerges as an attractive therapeutic target in cancer because it serves as a convergence point for many growth stimuli and, through its downstream substrates, controls cellular processes that contribute to the initiation and maintenance of cancer. Aberrant PI3K-dependent signaling occurs frequently in a wide range of tumor types, including endometrial, cervical, and ovarian cancers. The present study reviewed the available evidence regarding the potential impact of some mTOR pathway inhibitors in the treatment of gynecological cancer. Few advances in medical management have occurred in recent years in the treatment of advanced or recurrent gynecological malignancies, and a poor prognosis remains. Rationally designed molecularly targeted therapy is an emerging and important option in this setting; then more investigation in PI3K/AKT/mTOR pathway-targeted therapies is warranted.

The Potential of Targeting Ribosome Biogenesis in High-Grade Serous Ovarian Cancer

Overall survival for patients with ovarian cancer (OC) has shown little improvement for decades meaning new therapeutic options are critical. OC comprises multiple histological subtypes, of which the most common and aggressive subtype is high-grade serous ovarian cancer (HGSOC). HGSOC is characterized by genomic structural variations with relatively few recurrent somatic mutations or dominantly acting oncogenes that can be targeted for the development of novel therapies. However, deregulation of pathways controlling homologous recombination (HR) and ribosome biogenesis has been observed in a high proportion of HGSOC, raising the possibility that targeting these basic cellular processes may provide improved patient outcomes. The poly (ADP-ribose) polymerase (PARP) inhibitor olaparib has been approved to treat women with defects in HR due to germline BRCA mutations. Recent evidence demonstrated the efficacy of targeting ribosome biogenesis with the specific inhibitor of ribosomal RNA synthesis, CX-5461 in v-myc avian myelocytomatosis viral oncogene homolog (MYC)-driven haematological and prostate cancers. CX-5461 has now progressed to a phase I clinical trial in patients with haematological malignancies and phase I/II trial in breast cancer. Here we review the currently available targeted therapies for HGSOC and discuss the potential of targeting ribosome biogenesis as a novel therapeutic approach against HGSOC.

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSA via electrostatic binding affinity

Cisplatin combination drugs induce autophagy in HeLa cells and interact with HSAviaelectrostatic binding affinity.

New Insights into mTOR Signal Pathways in Ovarian-Related Diseases: Polycystic Ovary Syndrome and Ovarian Cancer

mTOR, the mammalian target of rapamycin, is a conserved serine/threonine kinase which belongs to the phosphatidyl-linositol kinase-related kinase (PIKK) family. It has two complexes called mTORC1 and mTORC2. It is well established that mTOR plays important roles in cell growth, proliferation and differentiation. Over-activation of the mTOR pathway is considered to have a relationship with the development of many types of diseases, including polycystic ovary syndrome (PCOS) and ovarian cancer (OC). mTOR pathway inhibitors, such as rapamycin and its derivatives, can directly or indirectly treat or relieve the symptoms of patients suffering from PCOS or OC. Moreover, mTOR inhibitors in combination with other chemical-molecular agents may have extraordinary efficacy. This paper will discuss links between mTOR signaling and PCOS and OC, and explore the mechanisms of mTOR inhibitors in treating these two diseases, with conclusions regarding the most effective therapeutic approaches.

Reduced BCL2 and CCND1 mRNA expression in human cervical cancer HeLa cells treated with a combination of everolimus and paclitaxel

Aim of the study

Cervical cancer is the second most common malignancy in women worldwide. Everolimus displays direct effects on growth and proliferation of cancer cells via inhibition of mammalian target of rapamycin (mTOR) protein, which is known to be associated with drug resistance. In this study, we aimed to investigate the effects of everolimus, gemcitabine, and paclitaxel in terms of cell viability and mRNA expression levels of GRP78, CCND1, CASP2, and BCL2 genes.

Material and methods

HeLa cells were treated with different doses of everolimus, gemcitabine, and paclitaxel. Cell viability was assessed using MTT assay, and obtained dose response curves were used for the calculations of inhibitory concentration (IC) values. At the end of the treatment times with selected doses, RNA isolation and cDNA synthesis were performed. Finally, GRP78, CCND1, CASP2, and BCL2 genes mRNA expression levels were analysed using quantitative PCR.

Results

The IC50 value of everolimus was 0.9 µM for 24-hour treatment. Moreover, the IC50 value of gemcitabine and paclitaxel was found to be around 18.1 µM and 7.08 µM, respectively. Everolimus, gemcitabine, and paclitaxel treatments alone did not change the GRP78, CCND1, BCL2 and CASP2 mRNA expression levels significantly. However, combined treatment of everolimus and paclitaxel significantly reduced BCL2 and CCND1 mRNA expression (p < 0.05). In contrast, this combination did not change GRP78 and CASP2 mRNA expression levels (p > 0.05).

Conclusions

Down-regulation of CCND1 and BCL2 expression may be an important mechanism by which everolimus increases the therapeutic window of paclitaxel in cervical cancers.

AMPK and PFKFB3 mediate glycolysis and survival in response to mitophagy during mitotic arrest

Blocking mitotic progression has been proposed as an attractive therapeutic strategy to impair proliferation of tumour cells. However, how cells survive during prolonged mitotic arrest is not well understood. We show here that survival during mitotic arrest is affected by the special energetic requirements of mitotic cells. Prolonged mitotic arrest results in mitophagy-dependent loss of mitochondria, accompanied by reduced ATP levels and the activation of AMPK. Oxidative respiration is replaced by glycolysis owing to AMPK-dependent phosphorylation of PFKFB3 and increased production of this protein as a consequence of mitotic-specific translational activation of its mRNA. Induction of autophagy or inhibition of AMPK or PFKFB3 results in enhanced cell death in mitosis and improves the anti-tumoral efficiency of microtubule poisons in breast cancer cells. Thus, survival of mitotic-arrested cells is limited by their metabolic requirements, a feature with potential implications in cancer therapies aimed to impair mitosis or metabolism in tumour cells.

Phase II study of capecitabine and the oral mTOR inhibitor everolimus in patients with advanced pancreatic cancer

Purpose

The combination of an mTOR inhibitor with 5-fluorouracil-based anticancer therapy is attractive because of preclinical evidence of synergy between these drugs. According to our phase I study, the combination of capecitabine and everolimus is safe and feasible, with potential activity in pancreatic cancer patients.

Methods

Patients with advanced adenocarcinoma of the pancreas were enrolled. Eligible patients had a WHO performance status 0–2 and adequate hepatic and renal functions. The treatment regimen consisted of capecitabine 1000 mg/m² BID day 1–14 and everolimus 10 mg daily (5 mg BID) in a continuous 21-day schedule. Tumor assessment was performed with CT-scan every three cycles. Primary endpoint was response rate (RR) according to RECIST 1.0. Secondary endpoints were progression-free survival, overall survival and 1-year survival rate.

Results

In total, 31 patients were enrolled. Median (range) treatment duration with everolimus was 76 days (1–431). Principal grade 3/4 toxicities were hyperglycemia (45 %), hand-foot syndrome (16 %), diarrhea (6 %) and mucositis (3 %). Prominent grade 1/2 toxicities were anemia (81 %), rash (65 %), mucositis (58 %) and fatigue (55 %). RR was 6 %. Ten patients (32 %) had stable disease resulting in a disease control rate of 38 %. Median overall survival was 8.9 months (95 % CI 4.6–13.1). Progression-free survival was 3.6 months (95 % CI 1.9–5.3).

Conclusions

The oral regimen with the combination of capecitabine and everolimus is a moderately active treatment for patients with advanced pancreatic cancer, with an acceptable toxicity profile at the applied dose level.

Parallel phase Ib studies of two schedules of buparlisib (BKM120) plus carboplatin and paclitaxel (q21 days or q28 days) for patients with advanced solid tumors

PURPOSE

Phosphatidylinositol-3-kinase I (PI3K) inhibition sensitizes a wide range of cancer cell lines to platinum/taxane-based chemotherapy. This phase I study combines buparlisib, a pan-class 1A PI3K inhibitor, with two schedules of carboplatin and paclitaxel for patients with advanced solid tumors (ClinicalTrials.gov, NCT01297452).

METHODS

There were two regimens: Group 1 received carboplatin AUC 5 and paclitaxel 175 mg/m(2), on day 1 of a 21-day cycle with pegfilgrastim support; Group 2 received carboplatin AUC 5 (day 1) and paclitaxel 80 mg/m(2) (days 1, 8, and 15) on a 28-day cycle without growth factor support. In both groups, three dose levels of buparlisib were explored: 50, 80, and 100 mg/day. Primary endpoint was to identify recommended phase II doses of buparlisib in both groups.

RESULTS

Thirty subjects enrolled, 16 in Group 1 and 14 in Group 2. The DLTs were elevated alkaline phosphatase (n = 1) and uncomplicated neutropenia (n = 2). The median numbers of cycles were 5 (Group 1) and 6 (Group 2). The MTDs for buparlisib were 100 mg/day in Group 1 and 80 mg/day in Group 2. Among 25 patients with measurable disease, the confirmed objective response rate was 20% (one complete response, four partial responses). Among three patients with known loss of PTEN expression, all derived clinical benefit from treatment.

CONCLUSION

The addition of buparlisib to carboplatin + paclitaxel was well tolerated, and preliminary activity was notable against tumors with loss of PTEN expression.

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.

Weekly nab-Rapamycin in patients with advanced nonhematologic malignancies: final results of a phase I trial

PURPOSE

This dose-finding phase I study investigated the maximum-tolerated dose (MTD) and safety of weekly nanoparticle albumin-bound rapamycin (nab-rapamycin) in patients with untreatable advanced nonhematologic malignancies.

EXPERIMENTAL DESIGN

nab-Rapamycin was administered weekly for 3 weeks followed by 1 week of rest, with a starting dose of 45 mg/m(2). Additional doses were 56.25, 100, 150, and 125 mg/m(2).

RESULTS

Of 27 enrolled patients, 26 were treated. Two dose-limiting toxicities (DLT) occurred at 150 mg/m(2) [grade 3 aspartate aminotransferase (AST) elevation and grade 4 thrombocytopenia], and two DLTs occurred at 125 mg/m(2) (grade 3 suicidal ideation and grade 3 hypophosphatemia). Thus, the MTD was declared at 100 mg/m(2). Most treatment-related adverse events (TRAE) were grade 1/2, including thrombocytopenia (58%), hypokalemia (23%), mucositis (38%), fatigue (27%), rash (23%), diarrhea (23%), nausea (19%), anemia (19%), hypophosphatemia (19%), neutropenia (15%), and hypertriglyceridemia (15%). Only one grade 3 nonhematologic TRAE (dyspnea) and one grade 3 hematologic event (anemia) occurred at the MTD. One patient with kidney cancer had a partial response and 2 patients remained on study for 365 days (patient with mesothelioma) and 238 days (patient with neuroendocrine tumor). The peak concentration (Cmax) and area under the concentration-time curve (AUC) of rapamycin increased with dose between 45 and 150 mg/m(2), except for a relatively low AUC at 125 mg/m(2). nab-Rapamycin significantly inhibited mTOR targets S6K and 4EBP1.

CONCLUSIONS

The clinical dose of single-agent nab-rapamycin was established at 100 mg/m(2) weekly (3 of 4 weeks) given intravenously, which was well tolerated with preliminary evidence of response and stable disease, and produced a fairly dose-proportional pharmacokinetic profile in patients with unresectable advanced nonhematologic malignancies.

Open-label randomized clinical trial of standard neoadjuvant chemotherapy with paclitaxel followed by FEC versus the combination of paclitaxel and everolimus followed by FEC in women with triple receptor-negative breast cancer†

BACKGROUND

Everolimus synergistically enhances taxane-induced cytotoxicity in breast cancer cells in vitro and in vivo in addition to demonstrating a direct antiproliferative activity. We aim to determine pharmacodynamics changes and response of adding everolimus to standard neoadjuvant chemotherapy in triple-negative breast cancer (TNBC).

PATIENTS AND METHODS

Phase II study in patients with primary TNBC randomized to T-FEC (paclitaxel 80 mg/m(2) i.v. weekly for 12 weeks, followed by 5-fluorouracil 500 mg/m(2), epirubicin 100 mg/m(2), and cyclophosphamide 500 mg/m(2) every 3 weeks for four cycles) versus TR-FEC (paclitaxel 80 mg/m(2) i.v. and everolimus 30 mg PO weekly for 12 weeks, followed by FEC). Tumor samples were collected to assess molecular changes in the PI3K/AKT/mTOR pathway, at baseline, 48 h, 12 weeks, and at surgery by reverse phase protein arrays (RPPA). Clinical end points included 12-week clinical response rate (12-week RR), pathological complete response (pCR), and toxicity.

RESULTS

Sixty-two patients were registered, and 50 were randomized, 27 received T-FEC, and 23 received TR-FEC. Median age was 48 (range 31-75). There was downregulation of the mTOR pathway at 48 h in the TR-FEC arm. Twelve-week RR by ultrasound were 29.6% versus 47.8%, (P = 0.075), and pCR were 25.9% versus 30.4% (P = 0.76) for T-FEC and TR-FEC, respectively. mTOR downregulation at 48 h did not correlate with 12-week RR in the TR-FEC group (P = 0.58). Main NCI grade 3/4 toxicities included anemia, neutropenia, rash/desquamation, and vomiting in both arms. There was one case of grade 3 pneumonitis in the TR-FEC arm. No grade 3/4 stomatitis occurred.

CONCLUSION

The addition of everolimus to paclitaxel was well tolerated. Everolimus downregulated mTOR signaling but downregulation of mTOR at 48 h did not correlate with 12-week RR in the TR-FEC group.

CLINICAL TRIAL NUMBER

NCT00499603.

Colocalized delivery of rapamycin and paclitaxel to tumors enhances synergistic targeting of the PI3K/Akt/mTOR pathway

Ongoing clinical trials target the aberrant PI3K/Akt/mammalian target of rapamycin (mTOR) pathway in breast cancer through administration of rapamycin, an allosteric mTOR inhibitor, in combination with paclitaxel. However, synergy may not be fully exploited clinically because of distinct pharmacokinetic parameters of drugs. This study explores the synergistic potential of site-specific, colocalized delivery of rapamycin and paclitaxel through nanoparticle incorporation. Nanoparticle drug loading was accurately controlled, and synergistic drug ratios established in vitro. Precise drug ratios were maintained in tumors 48 hours after nanoparticle administration to mice, at levels twofold greater than liver and spleen, yielding superior antitumor activity compared to controls. Simultaneous and preferential in vivo delivery of rapamycin and paclitaxel to tumors yielded mechanistic insights into synergy involving suppression of feedback loop Akt phosphorylation and its downstream targets. Findings demonstrate that a same time, same place, and specific amount approach to combination chemotherapy by means of nanoparticle delivery has the potential to successfully translate in vitro synergistic findings in vivo. Predictive in vitro models can be used to determine optimum drug ratios for antitumor efficacy, while nanoparticle delivery of combination chemotherapies in preclinical animal models may lead to enhanced understanding of mechanisms of synergy, ultimately opening several avenues for personalized therapy.

mTOR inhibitors and their clinical application in cervical, endometrial and ovarian cancers: a critical review

OBJECTIVES

The mechanistic (mammalian) targets of rapamycin (mTOR) inhibitors with known growth Inhibitory effect are currently in clinical trial for treatment of human cancer. The aim of this review is to present current incorporating these new drugs as single agents or in combination with other therapeutic modalities for treatment of gynecologic cancer.

METHODS

A PubMed search was conducted on "mTOR inhibitors" and "human cancer". The relevant studies published between the year 2000 to present were reviewed. Those related to gynecologic cancer (cervical, endometrial and ovarian) were selected for this manuscript. The result of published data and their clinical application in gynecologic malignancies are presented.

RESULTS

mTOR is directly involved in many cell signaling pathways, and mTOR inhibitors have demonstrated anti-tumor activity against a variety of human malignancies, including gynecologic cancers. Combinations of mTOR inhibitors with other treatment modalities, e.g. cytotoxic chemotherapy, hormonal therapies, and other targeted molecular agents, have shown encouraging results particularly in endometrial and ovarian cancer.

CONCLUSIONS

Patients with advanced or recurrent gynecologic cancers who have failed initial treatment are need of new treatment modalities. There is strong evidence that mTOR inhibitors limit tumor proliferation and progression. The PI3k/AKT/mTOR pathway is often deregulated in gynecologic cancer. Patients with PIK3CA mutations are more responsive to PI3K/AKT/mTOR inhibitors than patients without these mutations. Routine screening for PIK3CA mutations warrants further investigation when PI3K/AKT/mTOR inhibitors are considered in treatment of patients with gynecologic cancer.

Molecular alterations of PI3K/Akt/mTOR pathway: a therapeutic target in endometrial cancer

It is well established that the PI3K/Akt/mTOR pathway plays a central role in cell growth and proliferation. It has also been suggested that its deregulation is associated with cancer. Genetic alterations, involving components of this pathway, are often encountered in endometrial cancers. Understanding and identifying the rate-limiting steps of this pathway would be crucial for the development of novel therapies against endometrial cancer. This paper reviews alterations in the PI3K/Akt pathway, which could possibly contribute to the development of endometrial cancer. In addition, potential therapeutic targets of this pathway with emphasis on the mTOR inhibitors are also presented.

Arsenic trioxide overcomes rapamycin-induced feedback activation of AKT and ERK signaling to enhance the anti-tumor effects in breast cancer

Inhibitors of the mammalian target of rapamycin (mTORi) have clinical activity; however, the benefits of mTOR inhibition by rapamycin and rapamycin-derivatives (rapalogs) may be limited by a feedback mechanism that results in AKT activation. Increased AKT activity resulting from mTOR inhibition can be a result of increased signaling via the mTOR complex, TORC2. Previously, we published that arsenic trioxide (ATO) inhibits AKT activity and in some cases, decreases AKT protein expression. Therefore, we propose that combining ATO and rapamycin may circumvent the AKT feedback loop and increase the anti-tumor effects. Using a panel of breast cancer cell lines, we find that ATO, at clinically-achievable doses, can enhance the inhibitory activity of the mTORi temsirolimus. In all cell lines, temsirolimus treatment resulted in AKT activation, which was decreased by concomitant ATO treatment only in those cell lines where ATO enhanced growth inhibition. Treatment with rapalog also results in activated ERK signaling, which is decreased with ATO co-treatment in all cell lines tested. We next tested the toxicity and efficacy of rapamycin plus ATO combination therapy in a MDA-MB-468 breast cancer xenograft model. The drug combination was well-tolerated, and rapamycin did not increase ATO-induced liver enzyme levels. In addition, combination of these drugs was significantly more effective at inhibiting tumor growth compared to individual drug treatments, which corresponded with diminished phospho-Akt and phospho-ERK levels when compared with rapamycin-treated tumors. Therefore, we propose that combining ATO and mTORi may overcome the feedback loop by decreasing activation of the MAPK and AKT signaling pathways.

Active TGF-β signaling and decreased expression of PTEN separates angiosarcoma of bone from its soft tissue counterpart

Angiosarcomas constitute a heterogeneous group of highly malignant vascular tumors. Angiosarcoma of bone is rare and poorly characterized. For angiosarcoma of soft tissue, some pathways seem to be involved in tumor development. Our aim was to evaluate the role of these pathways in angiosarcoma of bone. We collected 37 primary angiosarcomas of bone and used 20 angiosarcomas of soft tissue for comparison. Immunohistochemistry was performed on constructed tissue microarrays to evaluate expression of CDKN2A, TP53, PTEN, BCL2, CDK4, MDM2, cyclin D1, β-catenin, transforming growth factor-β (TGF-β), CD105, phospho-Smad1, phospho-Smad2, hypoxia-inducible factor-1α, plasminogen activator inhibitor type 1 (PAI-1), VEGF, CD117 and glucose transporter--1. PIK3CA was screened for hotspot mutations in 19 angiosarcomas. In nearly 55% of the angiosarcoma of bone, the retinoblastoma (Rb) pathway was affected. Loss of CDKN2A expression was associated with a significantly worse prognosis. No overexpression of TP53 or MDM2 was found, suggesting that the TP53 pathway is not important in angiosarcoma of bone. Angiosarcoma of bone showed highly active TGF-β signaling with immunoreactivity for phospho-Smad2 and PAI-1. Although the phosphatidylinositol 3-kinase (PI3K)/Akt pathway seems to be active in both tumor groups, different mechanisms were involved: 41% of angiosarcoma of bone showed a decrease in expression of PTEN, whereas in angiosarcoma of soft tissue overexpression of KIT was found (90%). PIK3CA hotspot mutations were absent. In conclusion, the Rb pathway is involved in tumorigenesis of angiosarcoma of bone. The PI3K/Akt pathway is activated in both angiosarcoma of bone and soft tissue, however, with a different cause; PTEN expression is decreased in angiosarcoma of bone, whereas angiosarcomas of soft tissue show overexpression of KIT. Our findings support that angiosarcomas are a heterogeneous group of vascular malignancies. Both angiosarcoma of bone and soft tissue may benefit from therapeutic strategies targeting the PI3K/Akt pathway. However, interference with TGF-β signaling may be specifically relevant in angiosarcoma of bone.

A phase-1b study of everolimus plus paclitaxel in patients with small-cell lung cancer

BACKGROUND

The mammalian target of rapamycin (mTOR) pathway is dysregulated in small-cell lung cancer (SCLC) and everolimus is an oral mTOR inhibitor.

METHODS

This phase-1b study assessed everolimus safety at the levels of 2.5, 5, or 10 mg once daily in combination with paclitaxel (175 mg m(-2)) once every 3 weeks in previously treated SCLC patients. The primary end point was to determine the maximum tolerated dose of everolimus.

RESULTS

Among 21 enrolled patients, common drug-related adverse events were anaemia, neutropenia, thrombocytopenia, pain, hyperglycemia, and stomatitis. Out of 11 evaluable patients treated with everolimus at the level of 5 mg, 1 patient experienced dose-limiting toxicity (DLT) of grade 4 febrile neutropenia and grade 3 thrombocytopenia. The other two DLTs (grade 4 thrombocytopenia and grade 3 hyperglycemia) occurred in two out of three patients receiving everolimus 10 mg. The overall objective response rate was 28%.

CONCLUSION

Everolimus showed an acceptable safety profile and preliminary antitumour activity at the dose of 5 mg once daily when combined with 3-weekly paclitaxel 175 mg m(-2) in patients with SCLC.

Mithramycin A induces apoptosis by regulating the mTOR/Mcl-1/tBid pathway in androgen-independent prostate cancer cells

Mithramycin A (Mith) is an aureolic acid-type polyketide produced by various soil bacteria of the genus Streptomyces. Mith inhibits myeloid cell leukemia-1 (Mcl-1) to induce apoptosis in prostate cancer, but the molecular mechanism underlying this process has not been fully elucidated. The aim of this study was therefore to investigate the detailed molecular mechanism related to Mith-induced apoptosis in prostate cancer cells. Mith decreased the phosphorylation of mammalian target of rapamycin (mTOR) in both cell lines overexpressing phospho-mTOR compared to RWPE-1 human normal prostate epithelial cells. Mith significantly induced truncated Bid (tBid) and siRNA-mediated knock-down of Mcl-1 increased tBid protein levels. Moreover, Mith also inhibited the phosphorylation of mTOR on serine 2448 and Mcl-1, and increased tBid protein in prostate tumors in athymic nude mice bearing DU145 cells as xenografts. Thus, Mith acts as an effective tumor growth inhibitor in prostate cancer cells through the mTOR/Mcl-1/tBid signaling pathway.

Brassinin induces apoptosis in PC-3 human prostate cancer cells through the suppression of PI3K/Akt/mTOR/S6K1 signaling cascades

The oncogenic PI3K/Akt/mammalian target of rapamycin (mTOR) signaling axis and its downstream effector, the ribosomal protein S6 kinase 1 (S6K1) play a key role in mediating cell survival in various tumor cells. Here, we investigated the effects of brassinin (BSN), a phytoalexin first identified as a constituent of cabbage, on the PI3K/Akt/mTOR/S6K1 activation, cellular proliferation, and apoptosis in PC-3 human prostate cancer. BSN exerted a significant dose-dependent cytotoxicity and reduced constitutive phosphorylation of Akt against androgen-independent PC-3 cells as compared to androgen-dependent LNCaP cells. Moreover, knockdown of androgen receptor (AR) by small interfering RNA enhanced the potential effect of BSN on induction of apoptosis in LNCaP cells. BSN clearly suppressed the constitutive activation of PI3K/Akt/mTOR/S6K1 signaling cascade, which correlated with the induction of apoptosis as characterized by accumulation of cells in subG1 phase, positive Annexin V binding, TUNEL staining, loss of mitochondrial membrane potential, down-regulation of antiapoptotic and proliferative proteins, activation of caspase-3, and cleavage of PARP. Additionally, BSN could block broad-spectrum inhibition of PI3K/Akt/mTOR/S6K1 axes, and aberrant Akt activation by pcDNA3-myr-HA-Akt1 plasmid could not prevent the observed suppressive effect of BSN on constitutive mTOR activation. Finally, overexpression of Bcl-2 also attenuated BSN-mediated apoptosis in PC-3 cells. Taken together, our findings suggest that BSN can interfere with multiple signaling cascades involved in tumorigenesis and might be provided as a potential therapeutic candidate for both the prevention and treatment of prostate cancer.

Embelin inhibits growth and induces apoptosis through the suppression of Akt/mTOR/S6K1 signaling cascades

BACKGROUND

Akt/mTOR/S6K1 signaling cascades play an important role both in the survival and proliferation of tumor cells.

METHODS

In the present study, we investigated the effects of embelin (EB), identified primarily from the Embelia ribes plant, on the Akt/mTOR/S6K1 activation, associated gene products, cellular proliferation, and apoptosis in human prostate cancer cells.

RESULTS

EB exerted significant cytotoxic and suppressive effects on Akt and mTOR activation against androgen-independent PC-3 cells as compared to androgen-dependent LNCaP cells. Moreover, EB suppressed the constitutive activation of Akt/mTOR/S6K1 signaling cascade, which correlated with the induction of apoptosis as characterized by accumulation of cells in subG1 phase, positive Annexin V binding, down-regulation of anti-apoptotic (Bcl-2, Bcl-xL, survivin, IAP-1, and IAP-2) and proliferative (cyclin D1) proteins, activation of caspase-3, and cleavage of PARP. We also observed that EB can significantly enhance the apoptotic effects of a specific pharmacological Akt inhibitor when used in combination and also caused broad inhibition of all the three kinases in Akt/mTOR/S6K1 signaling axis in PC-3 cells.

CONCLUSIONS

EB inhibits multiple signaling cascades involved in tumorigenesis and can be used as a potential therapeutic candidate for both the prevention and treatment of prostate cancer.

A phase 1 study of everolimus plus docetaxel plus cisplatin as induction chemotherapy for patients with locally and/or regionally advanced head and neck cancer

BACKGROUND

Activation of the phosphatidylinositol-3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway is common in head and neck cancers, and it has been demonstrated that inhibition of mTOR complex 1 sensitizes cell lines to platinum and taxane chemotherapy. The authors conducted a phase 1 study to evaluate the addition of oral everolimus to cisplatin and docetaxel as induction chemotherapy for head and neck cancer.

METHODS

In this single-institution phase 1 study, 3 doses of daily everolimus were explored: 5 mg daily, 7.5 mg daily (administered as 5 mg daily alternating with 10 mg daily), and 10 mg daily of each 21-day cycle. Cisplatin and docetaxel doses were fixed (both were 75 mg/m(2) on day 1 of 21-day cycle) at each dose level with pegfilgrastim support. A standard 3 + 3 dose-escalation plan was used. After induction, patients were removed from protocol.

RESULTS

Eighteen patients were enrolled (15 men, 3 women), and their median Karnofsky performance status was 90. The most common toxicities were hyperglycemia, low hemoglobin, fatigue, and thrombocytopenia. Dose-limiting toxicities (DLTs) were neutropenic fever (1 event at dose level 2, 2 events at dose level 3), and all patients recovered fully from these DLTs. The maximum tolerated dose was exceeded at dose level 3. The progression-free survival rate at 1 year was 87.5% (95% confidence interval, 56.8%-96.7%); and, at 2 years, it was 76.6% (95% confidence interval, 41.2%-92.3%). Activating PI3K catalytic subunit α (PIK3CA) gene mutations were identified in 2 human papillomavirus-associated oropharyngeal cancers.

CONCLUSIONS

The phase 2 recommended dose was 7.5 mg daily for everolimus plus cisplatin and docetaxel (both at 75 mg/m(2) on day 1 of a 21-day cycle) given with pegfilgrastim support.

A review of oral toxicity associated with mTOR inhibitor therapy in cancer patients

Aphthous-like stomatitis has been identified as one of the most common dose-limiting toxicities associated with mTOR inhibitor therapy in cancer patients. The objective of this study was to summarize the cumulative oral toxicities associated with mTOR inhibitors in published oncology trials with respect to dose, schedule, and need for dose modifications. A review of all oncology-related clinical trials of mTOR inhibitors was conducted and standardized data was abstracted from each study. 44 studies were included in the analysis with a total of 2822 patients treated with temsirolimus (19 studies), everolimus (20 studies), and ridaforolimus (five studies) for a wide range of malignancies. At least one adverse event (AE) occurred in 74.4% of patients. Mucositis was the most frequent AE overall (73.4%), the third most frequent severe AE (20.7%), accounting for 27.3% dose reductions and 13.1% of discontinuations, and the most frequent dose limiting toxicity (52.5%). Mucositis typically occurred during the first cycle of therapy and was graded as mild to moderate in approximately 90% of the patients; severe mucositis generally occurred at higher doses. There were no clear differences in mucositis among the three agents and in most cases lesions resolved spontaneously. Oral mucositis is a frequent complication of mTOR inhibitor therapy and a significant cause of dose reductions and discontinuations in oncology trials. Prevention and management strategies should be investigated to improve tolerability and better permit effective long-term regimens.

The Biological Role of PI3K Pathway in Lung Cancer

Lung cancer is the primary cause of cancer-related mortality worldwide and although improvements in treatment have been achieved over the last few years, long-term survival rates for lung cancer patients remain poor. Therefore, there is an imperative need for molecularly targeted agents that will achieve long-term disease control. Numerous downstream molecular pathways, such as EGF/RAS/RAF/MEK/ERK and PI3K/AKT/mTOR are identified as having a key role in the pathogenesis of various forms of human cancer, including lung cancer. PI3K/AKT/mTOR signal pathway is an important intracellular signal transduction pathway with a significant role in cell proliferation, growth, survival, vesicle trafficking, glucose transport, and cytoskeletal organization. Aberrations in many primary and secondary messenger molecules of this pathway, including mutations and amplifications, are accounted for tumor cell proliferation, inhibition of apoptosis, angiogenesis, metastasis and resistance to chemotherapy-radiotherapy. In this review article, we investigate thoroughly the biological role of PI3K pathway in lung cancer and its contribution in the development of future therapeutic strategies.

Everolimus and its role in hormone-resistant and trastuzumab-resistant metastatic breast cancer

Advances in targeted therapies have improved progression-free and overall survival in women with metastatic breast cancer; however, regardless of efficacy, resistance almost always occurs eventually. Upregulation of the PI3K/AKT/mTOR pathway, which promotes cell growth and proliferation, is a means of escaping responsiveness to hormone therapy in hormone receptor-positive disease, or trastuzumab in HER2-positive disease. Everolimus, an inhibitor of mTOR, has shown promise in early clinical trials in metastatic breast cancer and is currently being studied in larger Phase II and III clinical trials, combined with hormone therapy or trastuzumab with or without cytotoxic chemotherapy. In this article, we discuss the mechanistic and preclinical data for everolimus, efficacy and safety results of clinical trials, and the landscape looking forward.

Arsenic trioxide synergizes with everolimus (Rad001) to induce cytotoxicity of ovarian cancer cells through increased autophagy and apoptosis

Phosphatidylinositol 3-kinase/AKT/mammalian target of rapamycin pathway plays a key role in the tumorigenesis of a variety of human cancers including ovarian cancer. However, inhibitors of this pathway such as Rad001 have not shown therapeutic efficacy as a single agent for this cancer. Arsenic trioxide (ATO) induces an autophagic pathway in ovarian carcinoma cells. We found that ATO can synergize with Rad001 to induce cytotoxicity of ovarian cancer cells. Moreover, we identified synergistic induction of autophagy and apoptosis as the likely underlying mechanism that is responsible for the enhanced cytotoxicity. The enhanced cytotoxicity is accompanied by decreased p-AKT levels as well as upregulation of ATG5-ATG12 conjugate and LC3-2, hallmarks of autophagy. Rad001 and ATO can also synergistically inhibit tumors in a xenograft animal model of ovarian cancer. These results thus identify and validate a novel mechanism to enhance and expand the existing targeted therapeutic agent to treat human ovarian cancer.

mTOR inhibitors in breast cancer: a systematic review

PI3K/AKT/mTOR pathway is a crucial mediator of tumor progression. As the PI3K/Akt pathway is heavily deregulated in breast cancer, the application of mTOR inhibitors in breast cancer patients seems warranted. This is the first systematic review according to PRISMA guidelines to synthesize all available data of mTOR inhibitors in all subcategories of breast cancer. The search strategy retrieved 16 studies evaluating everolimus (1492 patients), seven studies examining temsirolimus (1245 patients), one study evaluating sirolimus (400 patients) and two studies evaluating MKC-1 (60 patients). The Breast Cancer Trials of Oral Everolimus-2 (BOLERO-2) study has marked a turning point in the evaluation of everolimus in the treatment of estrogen receptor positive breast cancer. Given the positive results, everolimus has entered NCCN 2012 guidelines, and its approval of its combination with exemestane by FDA and EMA is imminent. In addition, the promising antitumor activity and long-term disease control further suggest that mTOR inhibition with everolimus may provide an avenue for achieving long-lasting benefit from trastuzumab-based therapy in HER2-positive patients. Regarding temsirolimus, it seems that the agent may play, in the future, a role in the treatment of metastatic breast cancer; importantly, however, there is an unmet need to find its optimal target subpopulation.

Everolimus: targeted therapy on the horizon for the treatment of breast cancer

The mammalian target of rapamycin (mTOR) is a signaling kinase of the phosphatidylinositol 3-kinase/protein kinase B (also known as Akt) signaling pathway that mediates cell growth and metabolism. Dysregulation of the mTOR pathway creates a favorable environment for the development and progression of many cancers, including breast cancer, and is associated with the development of resistance to endocrine therapy and to the anti-human epidermal growth factor receptor-2 (HER2) monoclonal antibody trastuzumab. Therefore, the addition of mTOR inhibitors to conventional breast cancer therapy has the potential to enhance therapeutic efficacy and/or overcome innate or acquired resistance. Everolimus, an mTOR inhibitor with demonstrated preclinical activity against breast cancer cell lines, has been shown to reverse Akt-induced resistance to hormonal therapy and trastuzumab. Phase I-II clinical trials have demonstrated that everolimus has promising clinical activity in women with HER2-positive, HER2-negative, and estrogen receptor-positive breast cancer when combined with HER2-targeted therapy, cytotoxic chemotherapy, and hormonal therapy, respectively. Everolimus is generally well tolerated; hematologic abnormalities and stomatitis are most common adverse events when this drug is combined with cytotoxic chemotherapy. Based on these promising results, everolimus is currently under evaluation in a series of phase III Breast Cancer Trials of Oral Everolimus (BOLERO) trials of women with HER2-positive and estrogen receptor-positive breast cancer. Results of these trials will help to establish the role of everolimus in the treatment of clinically important breast cancer subtypes.

A phase I study of temsirolimus plus carboplatin plus paclitaxel for patients with recurrent or metastatic (R/M) head and neck squamous cell cancer (HNSCC)

PURPOSE

The mammalian target of rapamycin complex 1 (mTORC1) is aberrantly activated in many head and neck squamous cell carcinomas (HNSCCs). This phase I study combines the mTORC1 inhibitor temsirolimus with carboplatin and paclitaxel.

METHODS

This was a single institution phase I study for patients with R/M HNSCC with a standard 3 + 3 design. Three doses of temsirolimus were planned: 15, 20, and 25 mg. Due to excessive toxicity with the original study regimen, the protocol was amended to carboplatin AUC 1.5, paclitaxel 80 mg/m(2), and temsirolimus (according to dose escalation plan), all on days 1 and 8 of a 21-day cycle.

RESULTS

18 patients (14 male, 4 female) enrolled, with median age 56 years (range 33-78). The most common toxicities were anemia, leukopenia, thrombocytopenia, and hyperglycemia. Among all patients treated, the confirmed objective partial response (cPR) rate was 22 %. DLT was not exceeded among 6 patients treated at dose level 3 of the revised protocol, and 4 of 6 subjects treated at this dose level had cPRs.

CONCLUSION

The phase II recommended regimen is temsirolimus 25 mg, carboplatin AUC 1.5, and paclitaxel 80 mg/m(2), all on days 1 and 8 of a 21-day cycle. A phase II study of this regimen in R/M HNSCC is ongoing.

A phase 1 study of weekly everolimus (RAD001) in combination with docetaxel in patients with metastatic breast cancer

BACKGROUND

Inhibition of mammalian target of rapamycin with everolimus may improve the efficacy of taxanes. Everolimus and docetaxel are both metabolized by CYP3A4, which could result in a pharmacokinetic (PK) interaction.

METHODS

Fifteen patients with metastatic breast cancer were treated with docetaxel (doses of 40-75 mg/m(2) intravenously on day 1 of a 21-day cycle) in combination with everolimus (doses ranging from 20 to 50 mg orally on days 1 and 8 of a 21-day cycle) in a phase 1 trial using the continuous reassessment method to determine maximum tolerated dose. The first 2 patients developed a dose-limiting toxicity (neutropenic infection), prompting a mandatory dose reduction and PK evaluation of both everolimus and docetaxel for patients enrolled in subsequent dosing cohorts.

RESULTS

Fifteen patients were treated. Dose-limiting toxicity included grade 3 mucositis (n = 1), prolonged grade 4 neutropenia (n = 1), and grade 3 infection/febrile neutropenia (n = 3). Day 8 of everolimus was commonly held for neutropenia despite a dose reduction in docetaxel to 40 mg/m(2). Eleven patients underwent complete PK evaluation for everolimus, and 9 patients underwent complete PK evaluation for both everolimus and docetaxel. Widely variable changes in clearance were seen for both drugs, and the study was terminated because of lack of efficacy and concerns regarding toxicity seen with the combination.

CONCLUSIONS

Weekly everolimus in combination with docetaxel every 3 weeks was associated with excessive neutropenia and variable clearance of both drugs, making combination therapy unpredictable, even at low doses of both drugs.

mTOR as a target in breast cancer: the emerging role of everolimus

SUMMARY The majority of patients with breast cancer are estrogen- and progesterone-receptor positive, and have benefited from the development of anti-estrogen therapies, such as tamoxifen and aromatase inhibitors. Unfortunately, metastatic patients will eventually develop resistance to these agents. Inhibitors of the mTOR, particularly everolimus, show promising activity in this group of patients. mTOR inhibition appears to reverse resistance to anti-estrogen therapy in the estrogen-receptor-/progesterone-receptor-positive subset. Additionally, they may have a similar effect by reversing anti-HER2 resistance in patients who overexpress HER2. This article reviews the mechanism of action of mTOR inhibitors and summarizes the available clinical data of their use in breast cancer.

Pharmacokinetic study of 3-in-1 poly(ethylene glycol)-block-poly(D, L-lactic acid) micelles carrying paclitaxel, 17-allylamino-17-demethoxygeldanamycin, and rapamycin

Concurrent delivery of multiple poorly water-soluble anticancer drugs has been a great challenge due to the toxicities exerted by different surfactants or organic solvents used in solubilizing individual drugs. We previously found that poly(ethylene glycol)-block-poly(D, L-lactic acid) (PEG-b-PLA) micelles can serve as a safe delivery platform for simultaneous delivery of paclitaxel (PTX), 17-allylamino-17-demethoxygeldanamycin (17-AAG), and rapamycin (RAP) to mice. The high tolerance of this polymeric micelle formulation by mice allowed us to investigate the pharmacokinetics of the 3 co-delivered drugs. In this study, it was shown that 3-in-1 PEG-b-PLA micelle delivering high doses of PTX, 17-AAG, and RAP (60, 60, and 30 mg/kg, respectively) significantly increased the values of the area under the plasma concentration-time curves (AUC) of PTX and RAP in mice compared to the drugs delivered individually, while the pharmacokinetic parameters of 17-AAG were similar in both 3-in-1 and single drug-loaded PEG-b-PLA micelle formulations. Moreover, pharmacokinetic study using 2-in-1 micelles indicated that the augmented AUC value of RAP was due to the co-delivery of 17-AAG, while the increase in AUC of PTX was more likely caused by the co-delivery of RAP. In contrast, when 3-in-1 and single drug-loaded PEG-b-PLA micelles were administrated at modest dose (PTX, 17-AAG, and RAP at 10, 10, and 5 mg/kg, respectively), pharmacokinetic differences of individual drugs between 3-in-1 and single drug formulations were eliminated. These results suggest that 3-in-1 PEG-b-PLA micelles can concurrently deliver PTX, 17-AAG, and RAP without changing the pharmacokinetics of each drug at modest doses, but altered pharmacokinetic profiles emerge when drugs are delivered at higher doses.

Neurotoxicity of biologically targeted agents in pediatric cancer trials

Biologically targeted agents offer the promise of delivering specific anticancer effects while limiting damage to healthy tissue, including the central and peripheral nervous systems. During the past 5-10 years, these agents were examined in preclinical and adult clinical trials, and are used with increasing frequency in children with cancer. This review evaluates current knowledge about neurotoxicity from biologically targeted anticancer agents, particularly those in pediatric clinical trials. For each drug, neurotoxicity data are reviewed in adult (particularly studies of brain tumors) and pediatric studies when available. Overall, these agents are well tolerated, with few serious neurotoxic effects. Data from younger patients are limited, and more neurotoxicity may occur in the pediatric population because these agents target pathways that control not only tumorigenesis but also neural maturation. Further investigation is needed into long-term neurologic effects, particularly in children.