Everolimus (RAD001) and anti-angiogenic cyclophosphamide show long-term control of gastric cancer growth in vivo

Metronomic dosing of cytotoxic drugs such as cyclophosphamide has shown anti-angiogenic activity, most likely by inducing hypoxia in tumors. Hypoxia leads to activation of escape mechanisms allowing tumor cell survival. This potentially limits the activity of anti-angiogenic strategies. We hypothesized that mTORC1 inhibition by everolimus (RAD001) leads to suppression of HIF-1alpha and VEGF resulting in synergistic anti-tumor activity in combination with anti-angiogenically dosed cyclophosphamide. In vitro, effects of everolimus on mTORC1 signaling, proliferation, cell cycle, HIF-1alpha expression and VEGF secretion were evaluated in two gastric cancer cell lines. In vivo, anti-tumor activity of everolimus in combination with metronomic cyclophosphamide was studied in a NCI-N87 human gastric cancer SCID mouse xenograft model. Expression of Ki-67 and HIF-1alpha, activated caspase 3, microvascular density (MVD) and tumor necrotic area assessed. Everolimus decreased proliferation and attenuated production of HIF-1alpha as well as VEGF in gastric cancer cells in vitro. In vivo, everolimus significantly inhibited tumor growth. This anti-tumor activity was linked to a significant increase in tumor necrotic area (p < 0.02) and trends for decreased proliferation, increased apoptosis, decreased HIF-1alpha and lower tumor MVD (p = n.s.). The combination of everolimus and cyclophosphamide resulted in a striking and highly significant long-term tumor growth control compared to monotherapy (p < 0.001), which was associated with a sharp increase in central tumor necrosis (p < 0.001). In conclusion, the combination of everolimus and metronomic cyclophosphamide showed synergistic anti-tumor activity. Depriving cancer cells by everolimus of factors necessary for their survival under hypoxia induced by anti-angiogenic chemotherapy appears to be a promising approach for treatment of gastric cancer.     

Effects of preset sequential administrations of sunitinib and everolimus on tumour differentiation in Caki-1 renal cell carcinoma

Background:

Sunitinib (VEGFR/PDGFR inhibitor) and everolimus (mTOR inhibitor) are both approved for advanced renal cell carcinoma (RCC) as first-line and second-line therapy, respectively. In the clinics, sunitinib treatment is limited by the emergence of acquired resistance, leading to a switch to second-line treatment at progression, often based on everolimus. No data have been yet generated on programmed alternating sequential strategies combining alternative use of sunitinib and everolimus before progression. Such strategy is expected to delay the emergence of acquired resistance and improve tumour control. The aim of our study was to assess the changes in tumours induced by three different sequences administration of sunitinib and everolimus.

Methods:

In human Caki-1 RCC xenograft model, sunitinib was alternated with everolimus every week, every 2 weeks, or every 3 weeks. Effects on necrosis, hypoxia, angiogenesis, and EMT status were assessed by immunohisochemistry and immunofluorescence.

Results:

Sunitinib and everolimus programmed sequential regimens before progression yielded longer median time to tumour progression than sunitinib and everolimus monotherapies. In each group of treatment, tumour growth control was associated with inhibition of mTOR pathway and changes from a mesenchymal towards an epithelial phenotype, with a decrease in vimentin and an increase in E-cadherin expression. The sequential combinations of these two agents in a RCC mouse clinical trial induced antiangiogenic effects, leading to tumour necrosis.

Conclusions:

In summary, our study showed that alternate sequence of sunitinib and everolimus mitigated the development of mesenchymal phenotype compared with sunitinib as single agent.     

Phase 1 trial of everolimus plus sunitinib in patients with metastatic renal cell carcinoma

BACKGROUND:

Simultaneous inhibition of the vascular epithelial growth factor (VEGF) and the mammalian target of rapamycin (mTOR) pathway may improve treatment response in advanced renal cell carcinoma (RCC). Everolimus, an oral mTOR inhibitor, and sunitinib, an oral tyrosine kinase inhibitor targeting VEGF, are standard agents in the management of metastatic RCC.

METHODS:

Sequential cohorts of 3 to 6 patients with advanced RCC received dose‐escalated combinations of sunitinib (37.5 or 50 mg daily, 4 weeks on/2 weeks off) with everolimus (2.5‐5 mg daily or 20‐30 mg weekly). Dose‐limiting toxicities (DLTs) were assessed in the first 6‐week cycle to determine maximum tolerated dose (MTD). Pharmacokinetic profiles were obtained.

RESULTS:

Twenty patients (13 clear cell and 7 nonclear cell RCC) were enrolled in 5 cohorts. Daily everolimus was not tolerated when combined with sunitinib; the first 2 patients on the second cohort suffered DLTs. With weekly everolimus, the MTD was 30 mg everolimus on days 7, 14, 21, and 28, plus 37.5 mg sunitinib on days 1 to 28 of a 42‐day cycle; however, chronic treatment was associated with grade 3 and 4 toxicities. A schedule of 20 mg everolimus weekly/37.5 mg sunitinib was tolerated as chronic therapy. Five patients (25%) had confirmed partial responses, and 3 had nonclear cell RCC. No unexpected accumulation of everolimus, sunitinib, or N‐desethyl sunitinib was observed.

CONCLUSIONS:

The combination of everolimus and sunitinib is associated with significant acute and chronic toxicities and is only tolerated at attenuated doses. Responses were observed in nonclear cell and clear cell RCC. Cancer 2012. © 2011 American Cancer Society.     

Targeting of tumor growth and angiogenesis underlies the enhanced antitumor activity of lenvatinib in combination with everolimus

The combination of lenvatinib, a multiple receptor tyrosine kinase inhibitor, plus everolimus, a mammalian target of rapamycin (mTOR) inhibitor, significantly improved clinical outcomes versus everolimus monotherapy in a phase II clinical study of metastatic renal cell carcinoma (RCC). We investigated potential mechanisms underlying the antitumor activity of the combination treatment in preclinical RCC models. Lenvatinib plus everolimus showed greater antitumor activity than either monotherapy in three human RCC xenograft mouse models (A‐498, Caki‐1, and Caki‐2). In particular, the combination led to tumor regression in the A‐498 and Caki‐1 models. In the A‐498 model, everolimus showed antiproliferative activity, whereas lenvatinib showed anti‐angiogenic effects. The anti‐angiogenic activity was potentiated by the lenvatinib plus everolimus combination in Caki‐1 xenografts, in which fibroblast growth factor (FGF)‐driven angiogenesis may contribute to tumor growth. The combination showed mostly additive activity in vascular endothelial growth factor (VEGF)‐activated, and synergistic activity against FGF‐activated endothelial cells, in cell proliferation and tube formation assays, as well as strongly suppressed mTOR‐S6K‐S6 signaling. Enhanced antitumor activities of the combination versus each monotherapy were also observed in mice bearing human pancreatic KP‐1 xenografts overexpressing VEGF or FGF. Our results indicated that simultaneous targeting of tumor cell growth and angiogenesis by lenvatinib plus everolimus resulted in enhanced antitumor activity. The enhanced inhibition of both VEGF and FGF signaling pathways by the combination underlies its superior anti‐angiogenic activity in human RCC xenograft models.     

Inhibition of Hedgehog signalling by NVP-LDE225 (Erismodegib) interferes with growth and invasion of human renal cell carcinoma cells

Background:

Multiple lines of evidence support that the Hedgehog (Hh) signalling has a role in the maintenance and progression of different human cancers. Therefore, inhibition of the Hh pathway represents a valid anticancer therapeutic approach for renal cell carcinoma (RCC) patients. NVP-LDE225 is a Smoothened (Smo) antagonist that induces dose-related inhibition of Hh and Smo-dependent tumour growth.

Methods:

We assayed the effects of NVP-LDE225 alone or in combination with everolimus or sunitinib on the growth and invasion of human RCC models both in vitro and in vivo. To this aim, we used a panel of human RCC models, comprising cells with acquired resistance to sunitinib – a multiple tyrosine kinase inhibitor approved as a first-line treatment for RCC.

Results:

NVP-LDE225 cooperated with either everolimus or sunitinib to inhibit proliferation, migration, and invasion of RCC cells even in sunitinib-resistant (SuR) cells. Some major transducers involved in tumour cell motility, including paxillin, were also efficiently inhibited by the combination therapy, as demonstrated by western blot and confocal microscopy assays. Moreover, these combined treatments inhibited tumour growth and increased animal survival in nude mice xenografted with SuR RCC cells. Finally, lung micrometastasis formation was reduced when mice were treated with NVP-LDE225 plus everolimus or sunitinib, as evidenced by artificial metastatic assays.

Conclusions:

Hedgehog inhibition by NVP-LDE225 plus sunitinib or everolimus bolsters antitumour activity by interfering with tumour growth and metastatic spread, even in SuR cells. Thus, this new evidence puts forward a new promising therapeutic approach for RCC patients.     

Systematic combination screening reveals synergism between rapamycin and sunitinib against human lung cancer

Mammalian target of rapamycin (mTOR) acts as a hub integrating signals from nutrient availability and growth factors and plays central roles in regulating protein synthesis and cell growth, which has been validated as a promising target for cancer therapy. Rapamycin and its analogues have emerged as the first generation of mTOR inhibitors, but their efficacy is modest in clinical settings. Combinatorial use of rapamycin with other drugs is a promising strategy to improve its anticancer activity. Here we developed an unbiased systematic binary screening platform aiming to discover new remedy for rapamycin-based cancer therapy. We found that sunitinib emerged as one of the clinically available anticancer drugs screened that displayed significant synergy with rapamycin in NSCLC cells. Combination of rapamycin with sunitinib resulted in enhanced cell cycle arrest in G1 phase, which was accompanied with enhanced suppression of mTOR signaling and disruption of the negative feedback loop that activate AKT upon mTORC1 inhibition. Furthermore, sunitinib and rapamycin displayed synergistic activity against tube formation by human microvessel endothelial cells as well as outgrowth of endothelial tubes and microvessels both in vitro and in vivo, which is associated with down-regulation of VEGF secretion and HIF1α expression. Our study demonstrated that new combinatorial regimen could be identified via systematic drug combination screening and established a mechanistic rationale for a combination approach using rapalogs and sunitinib in the treatment of human NSCLC.     

Everolimus in combination with letrozole inhibit human breast cancer MCF-7/Aro stem cells via PI3K/mTOR pathway: an experimental study

This study evaluated the effects of an mTOR inhibitor everolimus alone or in combination with letrozole on MCF-7/Aro (MCF-7 cells stably transfected with CYP19) in vitro and in vivo. In vitro studies, full-length CYP19 (aromatase) was cloned in a plasmid transfer vector pH ß-Aro and then transfected into MCF-7 stem cells which were ESA⁺CD44⁺CD24^?/low sorted by flow cytometry. MTT assays were used to quantify the inhibitory effect of the drugs on MCF-7/Aro stem cells (SCs) and non-stem cells (NSCs). Apoptosis and the cell cycle distributions of stem cells were examined by flow cytometry. The tumorigenicity of stem cells after treatment was investigated by soft agar colony formation assays. In vivo studies, the BALB/c mice were injected with MCF-7/Aro SCs, and the different treatments were administered. After necropsy, the expression of KI67, CD31, AKT1, phospho-AKT (Thr308), and mTOR was analyzed by immunohistochemistry. In vitro, compared with MCF-7/Aro NSCs, there were greater resistance to the standard treatment doses of letrozole and everolimus in MCF-7/Aro SCs (17- and 15-fold, respectively). Treatment with everolimus or letrozole resulted in growth inhibition of SCs in a dose-dependent manner. Compared with single-agent therapy, the combination of everolimus with letrozole was more effective in the inhibition of cell growth (P?<?0.001) and tumorigenicity (P?<?0.01). In addition, an increase in G1 cell cycle arrest and increases in early apoptosis were observed in the combination treatment group compared with either single-agent group. In vivo, the xenograft tumor sizes were significantly decreased in everolimus alone group compared to control group, and everolimus plus letrozole therapy was much more effective compared with either single agent alone (P?<?0.01). Compared with everolimus alone, the combination of everolimus and letrozole reduced the expression of KI67, mTOR, and phospho-AKT (Thr308; P?<?0.01). Everolimus has effective inhibition on aromatase-overexpressing stem cell in vitro and in vivo. The combination everolimus and letrozole could be more effective than either drug alone.     

Everolimus (RAD001) in the Treatment of Advanced Renal Cell Carcinoma: A Review

Historically, there have been few treatment options for patients with advanced renal cell carcinoma (RCC) besides immunotherapy with interleukin‐2 and interferon (IFN)‐α. Targeted therapies have improved clinical outcomes over the past several years. These include the vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitors sunitinib and sorafenib, which inhibit angiogenic signaling in endothelial cells and vascular pericytes predominantly through VEGFR and platelet‐derived growth factor receptor β. Also included is the anti‐VEGF monoclonal antibody bevacizumab used in combination with IFN‐α. These agents mediate their antitumor effects by interfering with the VEGF signaling pathway, thereby inhibiting angiogenesis and causing tumor shrinkage. However, ultimately, most patients develop resistance and experience disease progression during VEGF/VEGFR‐targeted therapy, and until the recent approval of the mammalian target of rapamycin (mTOR) inhibitor everolimus (RAD001), there were no agents available with proven activity in this setting. This review describes the clinical development of everolimus in advanced RCC and the rationale for the use of mTOR inhibitors after failure of VEGF/VEGFR inhibitors.     

Preclinical evaluation of the combination of mTOR and proteasome inhibitors with radiotherapy in malignant peripheral nerve sheath tumors

About one half of malignant peripheral nerve sheath tumors (MPNST) have Neurofibromin 1 (NF1) mutations. NF1 is a tumor suppressor gene essential for negative regulation of RAS signaling. Survival for MPNST patients is poor and we sought to identify an effective combination therapy. Starting with the mTOR inhibitors rapamycin and everolimus, we screened for synergy in 542 FDA approved compounds using MPNST cells with a native NF1 loss in both alleles. We further analyzed the cell cycle and signal transduction. In vivo growth effects of the drug combination with local radiation therapy (RT) were assessed in MPNST xenografts. The synergistic combination of mTOR inhibitors with bortezomib yielded a reduction in MPNST cell proliferation. The combination of mTOR inhibitors and bortezomib also enhanced the anti-proliferative effect of radiation in vitro. In vivo, the combination of mTOR inhibitor (everolimus) and bortezomib with RT decreased tumor growth and proliferation, and augmented apoptosis. The combination of approved mTOR and proteasome inhibitors with radiation showed a significant reduction of tumor growth in an animal model and should be investigated and optimized further for MPNST therapy.     

A tipping-point for apoptosis following dual inhibition of HER2 signaling network by T-DM1 plus GDC-0980 maximizes anti-tumor efficacy

HER2 signaling network and its complex relationship with the PI3K-AKT-mTOR pathway explain the acquired resistance to anti-HER2 therapy observed in clinics. Such complexity has been clinically evident from the limited efficacy of data in the BOLERO-1 and BOLERO-3 trials, which tested combinations of trastuzumab (T), everolimus, and chemotherapy in women with HER2+ advanced BC. In the following MARIANNE trial also, a combination of T-DM1 plus pertuzumab delivered a non-inferior but yet not superior PFS compared to trastuzumab plus a taxane. Algorithmic inhibition of PI3K/mTOR along with T or T-DM1 is, therefore, an attractive drug combination, and we tested the combination(s) in HER2+ BC, especially in T-resistant and PIK3CA mutated conditions. GDC-0980, a dual pan-PI3K/mTOR inhibitor alone or in combination with T or T-DM1, was examined in a panel of HER2+ T-sensitive (BT474, SKBR3), HER2+ T-resistant (BT474HerR), HER2+/PIK3CA mutant (HCC1954, MDA-MB453), and HER2+/PTEN mutant (HCC1569) BC cell lines. GDC-0980 re-sensitized trastuzumab-resistant, PIK3CA mutant, or PTEN mutant cells to T and acted additively with T. Importantly, this activity was more when GDC-0980 is combined with T-DM1. The combination (with T or with T-DM1) was then tested in the HER2+/T-sensitive, HER2+/T-resistant, and HER2+/PIK3CA mutated BC xenograft models for the anti-tumor effect. Along with its anti-tumor effect, GDC-0980 effectively decreased tumor angiogenesis (CD31 staining). Maximum anti-tumor (from tumor growth inhibition to tumor regression) efficiency was observed in all three xenograft models when T-DM1 was combined with GDC-0980. The anti-proliferative effects of GDC-0980 as evidenced by a decreased p-AKT (Ser473, The308), p-P70S6K, p-S6RP, and p-4EBP1, along with blockade of clonogenic 3D growth was accompanied by the initiation of apoptotic activity (annexin V, CASPASE3, cleaved PARP1 and mitochondrial depolarization); and was significantly superior when GDC-0980 combined with T-DM1. Interestingly, both trastuzumab and T-DM1 induce PD-L1 expression in HER2 amplified BC cells. Our data provide evidence that an oncogenic mutation of PIK3CA and HER2-amplification may represent biomarkers to identify patients who may benefit most from the use of GDC-0980 and an opportunity to include immunotherapy in the combination of anti-HER2 therapy.     

Toll-like receptor 9 agonist IMO cooperates with everolimus in renal cell carcinoma by interfering with tumour growth and angiogenesis

Background:

Targeting the mammalian target of rapamycin by everolimus is a successful approach for renal cell carcinoma (RCC) therapy. The Toll-like receptor 9 agonist immune modulatory oligonucleotide (IMO) exhibits direct antitumour and antiangiogenic activity and cooperates with both epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) inhibitors.

Methods:

We tested the combination of IMO and everolimus on models of human RCC with different Von-Hippel Lindau (VHL) gene status, both in vitro and in nude mice. We studied their direct antiangiogenic effects on human umbilical vein endothelial cells.

Results:

Both IMO and everolimus inhibited in vitro growth and survival of RCC cell lines, and their combination produced a synergistic inhibitory effect. Moreover, everolimus plus IMO interfered with EGFR-dependent signaling and reduced VEGF secretion in both VHL wild-type and mutant cells. In RCC tumour xenografts, IMO plus everolimus caused a potent and long-lasting cooperative antitumour activity, with reduction of tumour growth, prolongation of mice survival and inhibition of signal transduction. Furthermore, IMO and everolimus impaired the main endothelial cell functions.

Conclusion:

A combined treatment with everolimus and IMO is effective in VHL wild-type and mutant models of RCC by interfering with tumour growth and angiogenesis, thus representing a potentially effective, rationale-based combination to be translated in the clinical setting.     

In Vivo Antitumor and Antimetastatic Activity of Sunitinib in Preclinical Neuroblastoma Mouse Model

Neuroblastoma (NB) is one of the most common pediatric solid tumors originating from the neural crest lineage. Despite intensive treatment protocols including megatherapy with hematopoietic stem cell transplantation, the prognosis of NB patients remains poor. More effective therapeutics are required. High vascularity has been described as a feature of aggressive, widely disseminated NB. Our previous work demonstrated the overexpression of vascular endothelial growth factor (VEGF) in NB, and we showed that an anti-VEGF receptor (VEGFR-2) antibody could induce sustained NB tumor suppression and regression. Sunitinib is a kinase inhibitor targeting platelet-derived growth factor receptors and VEGFRs and, therefore, a promising antiangiogenic agent. In this study, we investigated the antitumor activity of sunitinib and its synergistic cytotoxicity with conventional (cyclophosphamide) and novel (rapamycin) therapies. Both NB cell lines and tumor-initiating cells from patient tumor samples were used in our in vitro and in vivo models for these drug testing. We show that sunitinib inhibits tumor cell proliferation and phosphorylation of VEGFRs. It also inhibits tumor growth, angiogenesis, and metastasis in tumor xenograft models. Low-dose sunitinib (20 mg/kg) demonstrates synergistic cytotoxicity with an mTOR inhibitor, rapamycin, which is more effective than the traditional chemotherapeutic drug, cyclophosphamide. These preclinical studies provide the evidence of antitumor activity of sunitinib both in the early stage of tumor formation and in the progressive metastatic disease. These studies also provide the framework for clinical trial of sunitinib, alone and in combination with conventional and novel therapies to increase efficacy and improve patient outcome in NB.     

The vascular disrupting agent BNC105 potentiates the efficacy of VEGF and mTOR inhibitors in renal and breast cancer

BNC105 is a tubulin targeting compound that selectively disrupts vasculature within solid tumors. The severe tumor hypoxia and necrosis that ensues translates to short term tumor growth inhibition. We sought to identify the molecular and cellular events activated following BNC105 treatment that drives tumor recovery. We investigated tumor adaptation to BNC105-induced hypoxia in animal models of breast and renal cancer. HIF-1α and GLUT-1 were found to be strongly upregulated by BNC105 as was the VEGF signaling axis. Phosphorylation of mTOR, 4E-BP-1 and elF2α were upregulated, consistent with increased protein synthesis and increased expression of VEGF-A. We sought to investigate the potential therapeutic utility of combining BNC105 with agents targeting VEGF and mTOR signaling. Bevacizumab and pazopanib target the VEGF axis and have been approved for first line use in renal cancer. Everolimus targets mTOR and is currently approved in second line therapy of renal and particular breast cancers. We combined these agents with BNC105 to explore the effects on tumor vasculature, tumor growth inhibition and animal survival. Bevacizumab hindered tumor vascular recovery following BNC105 treatment leading to greater tumor growth inhibition in a breast cancer model. Consistent with this, addition of BNC105 to pazopanib treatment resulted in a significant increase in survival in an orthotopic renal cancer model. Combination treatment of BNC105 with everolimus also increased tumor growth inhibition. BNC105 is currently being evaluated in a randomized phase II clinical trial in combination with everolimus in renal cancer.     

Synergistic interactions between sorafenib and everolimus in pancreatic cancer xenografts in mice

Purpose

Molecular targeting of cellular signaling pathways is a promising approach in cancer therapy, but often fails to achieve sustained benefit because of the activation of collateral cancer cell survival and proliferation pathways. We tested the hypothesis that a combination of targeted agents that inhibit compensatory pathways would be more effective than single agents in controlling pancreatic cancer cell growth. We investigated whether everolimus, an mTOR inhibitor, and sorafenib, a multi-kinase inhibitor, would together inhibit growth of low-passage, patient-derived pancreatic cancer xenografts in mice more efficaciously than either agent alone.

Methods

Tumor volume progression was measured following treatment with both drugs as single agents, in combination, and at multiple doses. Pharmacokinetics in tumors and other tissues was also assessed. Pharmacodynamic interactions were evaluated quantitatively.

Results

A 5-week regimen of daily oral doses of 10 mg/kg sorafenib and 0.5 mg/kg everolimus, alone and in combination, did not achieve significant tumor growth inhibition. Higher doses (20 mg/kg of sorafenib and 1 mg/kg of everolimus) inhibited tumor growth significantly when given alone and caused complete inhibition of growth when given in combination. Tumor volume progression was described by a linear growth model, and drug effects were described by Hill-type inhibition. Using population modeling approaches, dual-interaction parameter estimates indicated a highly synergistic pharmacodynamic interaction between the two drugs.

Conclusions

The results indicate that combinations of mTOR and multi-kinase inhibitors may offer greater efficacy in pancreatic cancer than either drug alone. Drug effects upon tumor stromal elements may contribute to the enhanced anti-tumor efficacy.     

Editor's choice: Current status and future directions of anti-angiogenic therapy for gliomas

Molecular targets for the pathological vasculature are the vascular endothelial growth factor (VEGF)/VEGF receptor axis, integrins, angiopoietins, and platelet-derived growth factor receptor (PDGFR), as well as several intracellular or downstream effectors like protein kinase C beta and mammalian target of rapamycin (mTOR). Besides hypoxic damage or tumor cell starvation, preclinical models imply vessel independent tumor regression and suggest differential effects of anti-angiogenic treatments on tumorous and nontumorous precursor cells or the immune system. Despite compelling preclinical data and positive data in other cancers, the outcomes of clinical trials with anti-angiogenic agents in gliomas by and large have been disappointing and include VEGF blockage with bevacizumab, integrin inhibition with cilengitide, VEGF receptor inhibition with sunitinib or cediranib, PDGFR inhibition with imatinib or dasatinib, protein kinase C inhibition with enzastaurin, and mTOR inhibition with sirolimus, everolimus, or temsirolimus. Importantly, there is a lack of real understanding for this negative data. Anti-angiogenic therapies have stimulated the development of standardized imaging assessment and the integration of functional MRI sequences into daily practice. Here, we delineate directions in the identification of molecularly or image-based defined subgroups, anti-angiogenic cotreatment for immunotherapy, and the potential of ongoing trials or modified targets to change the game.     

Comparative efficacy of vascular endothelial growth factor (VEGF) tyrosine kinase inhibitor (TKI) and mammalian target of rapamycin (mTOR) inhibitor as second-line therapy in patients with metastatic renal cell carcinoma after the failure of first-line VEGF TKI

Sequential therapy is a standard strategy used to overcome the limitations of targeted agents in metastatic renal cell carcinoma. It remains unclear whether a mammalian target of rapamycin (mTOR) inhibitor is a more effective second-line therapy after first-line vascular endothelial growth factor tyrosine kinase inhibitor (VEGF TKI) has failed than the alternative, VEGF TKI. A clinical database was used to identify all patients with renal cell carcinoma who failed at first-line VEGF TKI and then treated with second-line VEGF TKI or mTOR inhibitors in the Asan Medical Center. Patient medical characteristics, radiological response and survival status were assessed. Of the 83 patients who met the inclusion criteria, 41 received second-line VEGF TKI [sunitinib (n?=?16) and sorafenib (n?=?25)] and 42 were treated with mTOR inhibitors [temsirolimus (n?=?11) and everolimus (n?=?31)]. After a median follow-up duration of 23.9?months (95?% CI, 17.8?C30.0), progression-free survival was 3.0?months for both groups [hazard ratio (HR, VEGF TKI vs. mTOR inhibitor)?=?0.97, 95?% CI 0.59?C1.62, P?=?0.92]. Overall survival was 10.6?months for the VEGF TKI group and 8.2?months for the mTOR inhibitor group (HR?=?0.98, 95?% CI 0.57?C1.68, P?=?0.94). The two groups did not differ significantly in terms of disease control rate (51?% for VEGF TKI and 59?% for mTOR inhibitor, P?=?0.75). Second-line VEGF TKI seems to be as effective as mTOR inhibitors and may be a viable option as a second-line agent after first-line anti-VEGF agents have failed.     

A Population-Based Overview of Sequences of Targeted Therapy in Metastatic Renal Cell Carcinoma

BackgroundSeveral TTs are available to treat mRCC; however, the optimal sequence of therapy remains unknown.Patients and MethodsConsecutive population-based samples of patients with mRCC treated with TT were collected from 12 cancer centers via the International Metastatic Renal Cell Carcinoma Database Consortium. Patient characteristics, first-line and second-line progression-free survival rates and overall survival data were collected based on sequencing of TT. Multivariable analysis was performed when there were significant differences on univariable analysis.ResultsA total of 2106 patients were included with a median follow-up of 36 months; 907 (43%) and 318 (15%) patients received subsequent second-line and third-line TT, respectively. Baseline characteristics were well matched among different sequences apart from more patients with non–clear-cell histology in the vascular endothelial growth factor (VEGF) to mammalian target of rapamycin (mTOR) group compared with the VEGF to VEGF group sequence. When adjusting for the Heng risk criteria and non–clear-cell histology, the hazard ratio for death for the VEGF to mTOR group versus the VEGF to VEGF group was 0.833 (95% confidence interval [CI], 0.669-1.037; P = .1016). More specifically, the adjusted hazard ratio for death for the sunitinib to everolimus versus sunitinib to temsirolimus sequences was 0.774 (95% CI, 0.52-1.153; P = .2086).ConclusionIn this large multicenter analysis evaluating different sequences of TT in mRCC, no substantial effect on outcome based on sequence of TT was identified.     

Carboplatin selectively induces the VEGF stress response in endothelial cells: Potentiation of antitumor activity by combination treatment with antibody to VEGF

Vascular Endothelial Growth Factor (VEGF) functions as a key regulator in tumor angiogenesis. In addition, VEGF is an important survival factor for endothelial cells under chemical or physical stress. In our report, we show that treatment of endothelial cells with the chemotherapeutic agent carboplatin significantly increased the expression of VEGF. Furthermore, neutralization of secreted VEGF with specific polyclonal anti-VEGF antibodies or monoclonal antibody sensitized endothelial cells to carboplatin treatment and increased apoptosis several-fold. Interestingly, carboplatin treatment did not alter VEGF expression in tumor cells. Similarly, antibody to VEGF did not change the chemosensitivity of tumor cells to this drug. Most importantly, tumor-bearing animals treated with carboplatin showed an increase in VEGF immunoreactivity in the tumor vasculature, confirming the in vitro studies. Based on these observations, we determined whether neutralization of VEGF could enhance the anti-tumor activity of carboplatin in an in vivo ovarian cancer model system. A combination therapy consisting of a suboptimal dose of carboplatin (32.5 mg/kg/inj., q3d x 5; i.p.) and polyclonal anti-VEGF antibody (2 mg/inj., q3d x 10; i.p.) significantly enhanced solid tumor growth inhibition over individual monotherapies and included multiple complete responses. These findings suggest that VEGF is a critical endothelial cell specific survival factor that is induced by carboplatin and contributes to the protection of tumor vasculature during chemotherapy treatment. In addition, these results provide evidence for a potential mechanism that underlies enhanced anti-tumor activity achieved with chemotherapy and anti-VEGF antibody combination treatment regimens as recently reported in a number of clinical trials. We conclude that a similar type of combination therapy may be applicable to many types of malignancies since VEGF expression was differentially induced in the tumor host environment (i.e., tumor vasculature) and not in the tumor cells themselves; hence, this phenomenon may be independent of the type and origin of the primary cancer.     

The heparan sulfate mimetic PG545 interferes with Wnt/β-catenin signaling and significantly suppresses pancreatic tumorigenesis alone and in combination with gemcitabine

The heparan sulfate mimetic PG545 has been shown to exert anti-angiogenic and anti-metastatic activity in vitro and in vivo cancer models. Although much of this activity has been attributed to inhibition of heparanase and heparan sulfate-binding growth factors, it was hypothesized that PG545 may additionally disrupt Wnt signaling, an important pathway underlying the malignancy of pancreatic cancer. We show that PG545, by directly interacting with Wnt3a and Wnt7a, inhibits Wnt/β-catenin signaling leading to inhibition of proliferation in pancreatic tumor cell lines. Additionally, we demonstrate for the first time that the combination of PG545 with gemcitabine has strong synergistic effects on viability, motility and apoptosis induction in several pancreatic cell lines. In an orthotopic xenograft mouse model, combination of PG545 with gemcitabine efficiently inhibited tumor growth and metastasis compared to single treatment alone. Also, PG545 treatment alone decreased the levels of β-catenin and its downstream targets, cyclin D1, MMP-7 and VEGF which is consistent with our in vitro data. Collectively, our findings suggest that PG545 exerts anti-tumor activity by disrupting Wnt/β-catenin signaling and combination with gemcitabine should be considered as a novel therapeutic strategy for pancreatic cancer treatment.