sirolimus and vatalanib

Colorectal cancer is the second leading cause of cancer death in Switzerland. The nihilism that dominated the treatment of these patients for decades has been replaced by a measure of enthusiasm, given recent therapeutic advances. New anticancer drugs such as irinotecan and oxaliplatin have changed the standard chemotherapy treatment of metastatic colorectal cancer. However, the real hype has come from molecular targeted therapy. Identification of cellular processes characteristic of colon cancer has permitted therapeutic targeting with favorable therapeutic index. Inhibition of the epidermal growth factor receptor in the clinic has provided proof of principle that interruption of signal transduction cascades in patients has therapeutic potential. Angiogenesis, especially the vascular endothelial growth factor pathway, has been proven to be another highly successful molecular target. In this article, we will review molecular targets, which are under active clinical investigation in colon cancer.

Topics: Angiogenesis Inhibitors; Antibiotics, Antineoplastic; Antibodies, Monoclonal; Antibodies, Monoclonal, Humanized; Antineoplastic Agents; Antineoplastic Agents, Phytogenic; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzamides; Camptothecin; Cetuximab; Clinical Trials as Topic; Clinical Trials, Phase II as Topic; Colonic Neoplasms; Drug Delivery Systems; ErbB Receptors; Gefitinib; Humans; Imatinib Mesylate; Indoles; Irinotecan; Organoplatinum Compounds; Oxaliplatin; Phthalazines; Piperazines; Platelet-Derived Growth Factor; Protein Kinase Inhibitors; Pyridines; Pyrimidines; Pyrroles; Quinazolines; Quinolones; Receptors, Platelet-Derived Growth Factor; Receptors, Somatomedin; Signal Transduction; Sirolimus; Sunitinib

Vatalanib is an oral vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor (TKI), whereas everolimus inhibits mammalian target of rapamycin (mTOR). Combination therapy with VEGFR and mTOR inhibitors has not been well tolerated to date but may have efficacy in renal cell carcinoma (RCC).. A phase Ib study of vatalanib and everolimus was performed in patients with advanced solid tumors to determine the maximum tolerated dose (MTD), safety, and tolerability of the combination. A dose-expansion cohort of 20 patients with metastatic RCC was studied to further define toxicity and preliminary efficacy in patients with RCC.. We evaluated 32 patients over 3 dose levels and a dose-expansion cohort. The most common toxicities of any grade were proteinuria, fatigue, hypertriglyceridemia, nausea, and vomiting. Dose-limiting toxicities (DLTs) included severe hypertension, diarrhea, neutropenia, mucositis, and fatigue. The MTD for the combination was vatalanib 1000 mg daily and everolimus 5 mg daily. In all patients, median overall survival (OS) was 16.3 months. In patients with RCC, median progression-free survival (PFS) was 5.8 months, and OS was 16.5 months. OS was significantly better in treatment-naive patients (25.1 months) compared with patients who had received previous vascular endothelial growth factor (VEGF)-targeted therapy (6.3 months). Seven of 24 (29.2%) evaluable patients demonstrated a partial response, and an additional 15 patients exhibited stable disease. Long-term tolerability (> 1 year) was demonstrated in 19% of patients.. Relevant doses of vatalanib and everolimus were achieved in combination, with expected toxicities. A substantial number of patients with RCC achieved an objective response in the treatment-naive setting, with prolonged tolerability and survival. Further comparative phase II/III studies of specifically targeted VEGF and mTOR inhibitor combinations may be warranted in patients with RCC.

Topics: Adult; Aged; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Carcinoma, Renal Cell; Everolimus; Female; Follow-Up Studies; Humans; Kidney Neoplasms; Male; Maximum Tolerated Dose; Middle Aged; Molecular Targeted Therapy; Neoplasm Staging; Phthalazines; Prognosis; Protein Kinase Inhibitors; Pyridines; Receptors, Vascular Endothelial Growth Factor; Sirolimus; Survival Rate; TOR Serine-Threonine Kinases

Everolimus (RAD001, Afinitor) is an mTORC1 pathway inhibitor, and vatalanib (PTK/ZK) is a pan VEGF-R tyrosine kinase inhibitor (TKI). These two drugs have been shown to have overlapping but also distinct anti-angiogenic effects. Consequently, we investigated the pharmacokinetics (PK) and pharmacodynamics (PD) of their combination in vivo.. Murine melanoma B16/BL6 cells were grown orthotopically in BL6/C57 mice by injection into the derma of both ears to create a primary tumour which metastasized rapidly to the cervical lymph nodes. Mice were treated daily p.o. with PTK/ZK (100 mg/kg) or everolimus (1 mg/kg) or their combination, and anti-tumour efficacy (PD) assessed. In the same model, plasma PK of everolimus was measured following single doses of the monotherapy or combination schedules.. Two independent experiments showed that combination of everolimus and PTK/ZK caused at least additive increases in anti-tumour activity compared to either monotherapy, without increases in toxicity. Pooling the data to improve the statistical power demonstrated the interactions to be synergistic. PK modelling showed that although PTK/ZK increased everolimus plasma concentrations by about twofold, this PK drug-drug interaction could not account for the increased anti-tumour effect of the combination. Modelling of the PTK/ZK dose-response curve in this model suggested that any effect of everolimus on the PK of PTK/ZK was unlikely to affect efficacy. Measurement of changes in tumour and plasma VEGF levels at the endpoint of therapy confirmed earlier observations of differential effects of these two agents.. The combination of everolimus and PTK/ZK hold promise for the treatment of human cancers.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Synergism; Everolimus; Female; Mechanistic Target of Rapamycin Complex 1; Melanoma, Experimental; Mice; Mice, Inbred C57BL; Models, Biological; Multiprotein Complexes; Neoplasm Metastasis; Phthalazines; Proteins; Pyridines; Receptors, Vascular Endothelial Growth Factor; Sirolimus; TOR Serine-Threonine Kinases

The vascular endothelial growth factor (VEGF) is a central mediator of tumor-induced angiogenesis. Everolimus, a mammalian target of rapamycin (mTOR) inhibitor, decreases VEGF-secretion of cancer cells. Vatalanib is a selective inhibitor of VEGF receptors 1-3. In the present study it was hypothesized that dual inhibition of VEGF signaling by inhibition of VEGF production and VEGF receptor signaling leads to synergistic anti-tumor effects. In vitro, effects of vatalanib and everolimus on cell proliferation, cell cycle, apoptosis and signal transduction were examined in three gastric cancer cell lines. Effects on angiogenesis were assessed using tube formation assays of cultured human umbilical vein endothelial cells (HUVECs). In vivo, the antitumor effect of compounds was studied using a gastric cancer xenograft nude mouse model. VEGF of murine origin (mVEGF) and human cancer cell-derived VEGF (hVEGF) were studied separately by specific ELISAs. Tumor vascularization and proliferation were quantified by immunohistochemistry. In vitro, everolimus but not vatalanib decreased gastric cancer proliferation without inducing apoptosis. Vatalanib abolished endothelial cell tube formation, whereas inhibition of tube formation by everolimus was incomplete. In vivo, the combination of vatalanib with everolimus was superior to single agent treatments and reduced tumor size by about 50% relative to everolimus monotherapy (p < 0.005). Pharmacodynamic analysis of VEGF plasma level showed a decrease of hVEGF by everolimus and indicated a trend towards lower mVEGF level only in the combination group. In line, there was a tendency for lower vascular density and proliferation for combination treatment. We conclude that in a preclinical model of gastric cancer the antitumor activity of vatalanib can be augmented by everolimus.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Enzyme-Linked Immunosorbent Assay; Everolimus; Humans; Immunosuppressive Agents; Mice; Mice, Nude; Neovascularization, Pathologic; Phthalazines; Protein Kinase Inhibitors; Pyridines; Receptors, Vascular Endothelial Growth Factor; Signal Transduction; Sirolimus; Stomach Neoplasms; TOR Serine-Threonine Kinases; Tumor Burden; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

Comparison of the antiangiogenic/vascular properties of the oral mammalian target of rapamycin (mTOR) inhibitor RAD001 (everolimus) and the vascular endothelial growth factor receptor (VEGFR) inhibitor vatalanib (PTK/ZK).. Antiproliferative activity against various tumor histotypes and downstream effects on the mTOR pathway were measured in vitro. In vivo, antitumor activity, plasma, and tumor RAD001 levels were measured. Activity in several different angiogenic/vascular assays in vitro and in vivo was assessed and compared with PTK/ZK.. RAD001 inhibited proliferation in vitro (IC50 values<1 nmol/L to >1 micromol/L), and in sensitive and insensitive tumor cells, pS6 kinase and 4E-BP1 were inhibited. Activity in vitro did not correlate with activity in vivo and significant responses were seen in tumors with IC50 values>10-fold higher than tumor RAD001 concentrations. In vitro, RAD001 inhibited the proliferation of VEGF-stimulated and fibroblast growth factor-stimulated human endothelial cells but not dermal fibroblasts and impaired VEGF release from both sensitive and insensitive tumor cells but did not inhibit migration of human endothelial cells. In vivo, in tumor models derived from either sensitive or insensitive cells, RAD001 reduced Tie-2 levels, the amount of mature and immature vessels, total plasma, and tumor VEGF. RAD001 did not affect blood vessel leakiness in normal vasculature acutely exposed to VEGF nor did it affect tumor vascular permeability (Ktrans) as measured by dynamic contrast-enhanced magnetic resonance imaging. However, the pan-VEGFR inhibitor PTK/ZK inhibited endothelial cell migration and vascular permeability but had less effect on mature vessels compared with RAD001.. VEGFR and mTOR inhibitors show similar but also distinct effects on tumor vascular biology, which has implications for their clinical activity alone or in combination.

Topics: Angiogenesis Inhibitors; Animals; Cell Movement; Cell Proliferation; Everolimus; Female; Humans; Immunoenzyme Techniques; Magnetic Resonance Imaging; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Neoplasms, Experimental; Neovascularization, Pathologic; Phthalazines; Protein Kinase Inhibitors; Protein Kinases; Pyridines; Rats; Rats, Inbred BN; Rats, Inbred WF; Receptor, TIE-2; Receptors, Vascular Endothelial Growth Factor; Sirolimus; Tissue Distribution; TOR Serine-Threonine Kinases; Transplantation, Heterologous; Vascular Endothelial Growth Factor A

An intact VEGF receptor/PI3K/PKB/Akt signaling cascade protects endothelial cells from apoptotic stress-stimuli and mediates the formation of new blood vessels in pathological conditions such as cancer. Therefore, downregulation of this signaling cascade is of clinical interest for antiangiogenic cancer therapy. In this report, we demonstrate that VEGF controls the protein stability of the serine-threonine kinase PKB/Akt via inhibition of PKB/Akt protein degradation. VEGF deprivation or blockage of the VEGF signal transduction cascade with the VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 resulted in a specific decrease of the PKB/Akt protein level and subsequent cellular restimulation with VEGF rescued its stability. Real-time quantitative RT-PCR analysis demonstrated that VEGF does not regulate PKB/Akt gene expression. On the other hand, broad range inhibitors of caspases and the proteasome complex prevented VEGF-dependent downregulation of the PKB/Akt protein level indicating that PKB/Akt protein stability is regulated by VEGF-controlled proteolysis. Inhibition of the VEGF receptor and PKB/Akt-downstream PIK-related mTOR-kinase by rapamycin also neutralized the VEGF-protective effect in an PKB/Akt gene expression-independent way but results in proteolysis-dependent reduction of PKB/Akt protein stability. These results demonstrate a novel regulatory mechanism of the activated VEGF receptor/mTOR-signal transduction pathway to control the protein stability of PKB/Akt and survival threshold in endothelial cells.

Topics: Caspase Inhibitors; Caspases; Cell Death; Cell Survival; Cells, Cultured; Cysteine Endopeptidases; Cysteine Proteinase Inhibitors; Endothelium, Vascular; Enzyme Stability; Multienzyme Complexes; Phthalazines; Proteasome Endopeptidase Complex; Protein Kinases; Protein Serine-Threonine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-akt; Pyridines; Receptors, Vascular Endothelial Growth Factor; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Vascular Endothelial Growth Factor A