新型酪氨酸激酶抑制剂PTK787/ZK222584的研究进展

PTK787/ZK222584是一种新型血管内皮生长因子受体酪氨酸激酶抑制剂,通过抑制酪氨酸激酶的磷酸化,阻断信号传导,抑制肿瘤新生血管的形成从而抑制肿瘤的生长。临床前研究和临床试验研究显示该药对多种肿瘤有抗肿瘤活性,不良反应较轻。     

The histone deacetylase inhibitor NVP-LAQ824 inhibits angiogenesis and has a greater antitumor effect in combination with the vascular endothelial growth factor receptor tyrosine kinase inhibitor PTK787/ZK222584

Chromatin remodeling agents such as histone deacetylase inhibitors have been shown to modulate gene expression in tumor cells and inhibit tumor growth and angiogenesis. Vascular endothelial growth factor (VEGF) and VEGF receptors represent critical molecular targets for antiangiogenesis therapy. In this study, we investigated the biological effect of the histone deacetylase inhibitor NVP-LAQ824 in combination with the VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 on tumor growth and angiogenesis. We report that treatment with NVP-LAQ824 affected tumor and endothelial cells and was associated with increased histone acetylation, p21 up-regulation, and growth inhibition. In addition, NVP-LAQ824 treatment inhibited the expression of angiogenesis-related genes such as angiopoietin-2, Tie-2, and survivin in endothelial cells and down-regulated hypoxia-inducible factor 1-alpha and VEGF expression in tumor cells. Combination treatment with NVP-LAQ824 and PTK787/ZK222584 was more effective than single agents in inhibiting in vitro and in vivo VEGF-induced angiogenesis. Endothelial cell proliferation, tube formation, and invasion into the Matrigel plugs were reduced. In mouse models with established subcutaneous prostate (PC3) and orthotopic breast tumors (MDA-MB321), this combination treatment induced 80 to 85% inhibition of tumor growth without overt toxicity. These results suggest that the combination of histone deacetylase inhibitors and VEGF receptor inhibitors may target multiple pathways in tumor progression and angiogenesis and represents a novel therapeutic approach in cancer treatment.     

PTK787/ZK 222584, a small molecule tyrosine kinase receptor inhibitor of vascular endothelial growth factor (VEGF), has modest activity in myelofibrosis with myeloid metaplasia

Angiogenesis is part of the pathophysiology of myelofibrosis with myeloid metaplasia (MMM). PTK787/ZK 222584 (PTK/ZK) is a novel inhibitor of vascular endothelial growth factor receptors. Twenty-nine patients with MMM received a continuous dosing schedule of PTK/ZK doses of 500 or 750 mg twice daily (BID). Transient potentially PTK/ZK related mild nausea, vomiting, dizziness, fatigue, thrombocytopenia, or anorexia occurred in 15% of patients. Dose limiting toxicities of dyspepsia, proteinurea, and/or mucositis were observed in patients treated with 750 mg BID. One (3%) and five (17%) patients achieved complete remission and clinical improvement, respectively. PTK/ZK has modest activity in patients with MMM.     

PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration

PTK787/ZK 222584 (1-[4-chloroanilino]-4-[4-pyridylmethyl] phthalazine succinate) is a potent inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, active in the submicromolar range. It also inhibits other class III kinases, such as the platelet-derived growth factor (PDGF) receptor beta tyrosine kinase, c-Kit, and c-Fms, but at higher concentrations. It is not active against kinases from other receptor families, such as epidermal growth factor receptor, fibroblast growth factor receptor-1, c-Met, and Tie-2, or intracellular kinases such as c-Src, c-Abl, and protein kinase C-alpha. PTK787/ZK 222584 inhibits VEGF-induced autophosphorylation of kinase insert domain-containing receptor (KDR), endothelial cell proliferation, migration, and survival in the nanomolar range in cell-based assays. In concentrations up to 1 microM, PTK787/ZK 222584 does not have any cytotoxic or antiproliferative effect on cells that do not express VEGF receptors. After oral dosing (50 mg/kg) to mice, plasma concentrations of PTK787/ZK 222584 remain above 1 microM for more than 8 h. PTK787/ZK 222584 induces dose-dependent inhibition of VEGF and PDGF-induced angiogenesis in a growth factor implant model, as well as a tumor cell-driven angiogenesis model after once-daily oral dosing (25-100 mg/kg). In the same dose range, it also inhibits the growth of several human carcinomas, grown s.c. in nude mice, as well as a murine renal carcinoma and its metastases in a syngeneic, orthotopic model. Histological examination of tumors revealed inhibition of microvessel formation in the interior of the tumor. PTK787/ZK 222584 is very well tolerated and does not impair wound healing. It also does not have any significant effects on circulating blood cells or bone marrow leukocytes as a single agent or impair hematopoetic recovery after concomitant cytotoxic anti-cancer agent challenge. This novel compound has therapeutic potential for the treatment of solid tumors and other diseases where angiogenesis plays an important role.     

Both antiangiogenesis- and angiogenesis-independent effects are responsible for hepatocellular carcinoma growth arrest by tyrosine kinase inhibitor PTK787/ZK222584

Vascular endothelial growth factor (VEGF) plays an important role in tumor angiogenesis of hepatocellular carcinoma. Inhibition of VEGF receptors could theoretically reduce angiogenesis and tumor growth in hepatocellular carcinoma, but this remains to be proven with an experimental study. This study examined the angiogenesis-dependent and angiogenesis-independent activities of PTK787/ZK222584 (PTK787), a tyrosine kinase inhibitor of VEGF receptors, in nude mice bearing human hepatocellular carcinoma xenografts. The in vitro effects of PTK787 on proliferation, apoptosis, and cell cycle distribution in human hepatocellular carcinoma cell lines were also studied. Oral administration of PTK787 resulted in a significant reduction in tumor volume and microvessel formation of hepatocellular carcinoma xenografts in nude mice. PTK787 inhibited tumor cell proliferation in a dose-dependent manner and also induced tumor cells to undergo apoptosis both in vivo and in vitro. The proapoptotic response was associated with down-regulation of Bcl-2 and Bcl-x(L) expression and induction of cleavage of caspase-3. In addition, PTK787 induced growth arrest in hepatocellular carcinoma cells, which was associated with G1 arrest and partial G2-M block. This effect correlated with an increase in p21(WAF1/ CIP1) (p21) and p27KIP1 (p27) protein expression. In conclusion, this study showed that PTK787 is a potent inhibitor of tumor growth in hepatocellular carcinoma by both antiangiogenic effect and direct effects on tumor cell proliferation and apoptosis. Our data suggest that blockage of VEGF receptors may provide an effective therapeutic approach for human hepatocellular carcinoma.     

Soluble markers for the assessment of biological activity with PTK787/ZK 222584 (PTK/ZK), a vascular endothelial growth factor receptor (VEGFR) tyrosine kinase inhibitor in patients with advanced colorectal cancer from two phase I trials.

BACKGROUND: Plasma and serum biomarkers of angiogenesis and activated endothelial cells were evaluated to assess biological activity of PTK787/ZK 222584 (PTK/ZK), a novel oral angiogenesis inhibitor targeting all known vascular endothelial growth factor (VEGF) receptor tyrosine kinases. PATIENTS AND METHODS: Patients with colorectal cancer (CRC) (n=63) were enrolled into two phase I/II dose escalation trials of PTK/ZK in 28-day cycles until discontinuation. Patients with stable disease for > or =2 months were categorized as 'non-progressors'. Plasma markers of angiogenesis, VEGF-A and basic fibroblast growth factor (bFGF), and the serum markers of activated endothelial cells, sTIE-2 and sE-Selectin, were assessed at baseline, and pre-dose on days 1, 8, 15, 22 and 28 of every cycle, with additional assessments 10 h post-dose on days 1 and 15. The percentage change from baseline was subsequently correlated with AUC and C(max) of PTK/ZK on day 1, cycle 1 and clinical outcome. RESULTS: A dose-dependent increase in plasma VEGF-A and bFGF was observed in the first cycle of PTK/ZK treatment. The correlation of change in plasma VEGF-A with AUC and C(max) was characterized by an E(max) model, suggesting that a change of > or =150% from baseline VEGF-A correlated with non-progressive disease. Change from baseline plasma VEGF-A within the first cycle of treatment was significantly correlated with clinical outcome by logistic regression analysis (P=0.027). CONCLUSIONS: In patients with CRC treated with PTK/ZK, changes in plasma VEGF-A and bFGF demonstrate biological activity of PTK/ZK, may help to establish optimal dose and correlate with outcome.     

Effect of VEGF receptor inhibitor PTK787/ZK222584 [correction of ZK222548] combined with ionizing radiation on endothelial cells and tumour growth.

The vascular endothelial growth factor (VEGF) receptor is a major target for anti-angiogenesis-based cancer treatment. Here we report the treatment effect of ionizing radiation in combination with the novel orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 on endothelial cell proliferation in vitro and with tumour xenografts in vivo. Combined treatment of human umbilical vein endothelial cells with increasing doses of PTK787/ZK222584 and ionizing radiation abrogated VEGF-dependent proliferation in a dose-dependent way, but inhibition of endothelial cell proliferation was not due to apoptosis induction. In vivo, a combined treatment regimen of PTK787/ZK222584 (4 x 100 mg/kg) during 4 consecutive days in combination with ionizing radiation (4 x 3 Gy) exerted a substantial tumour growth delay for radiation-resistant p53-dysfunctional tumour xenografts derived from SW480 colon adenocarcinoma cells while each treatment modality alone had only a minimal effect on tumour size and neovascularization. SW480 tumours from animals that received a combined treatment regimen, displayed not only an extended tumour growth delay but also a significant decrease in the number of microvessels in the tumour xenograft. These results support the model of a cooperative anti-tumoral effect of angiogenesis inhibitor and irradiation and show that the orally bioavailable VEGF receptor tyrosine kinase inhibitor PTK787/ZK222584 is suitable for combination therapy with irradiation.     

PTK787/ZK 222584, a specific vascular endothelial growth factor-receptor tyrosine kinase inhibitor,affects the anatomy of the tumor vascular bed and the functional vascular properties as detected by dynamic enhanced magnetic resonance imaging

Antiangiogenic therapy is a promising new strategy of inhibiting tumor growthand formation of metastases. Recently, a number of compounds with different effects on tumor endothelial cells have entered clinical trials and revealed the need for diagnostic methods to detect their biological activity. Dynamic enhanced magnetic resonance imaging (dyMRI) is used in most clinical trials with antiangiogenic active compounds. We evaluated this method by using PTK787/ZK 222584, a specific inhibitor of the VEGF-receptor tyrosine kinases, which showed antitumoral and antiangiogenic activity in a murine renal cell carcinoma (RENCA) model. After intrarenal application of RENCA cells, mice developed a primary tumor and metastases to the lung and abdominal lymph nodes. After daily oral therapy for 21 days with either PTK787/ZK 222584 at a dose of 50 mg/kg or vehicle, primary tumors of all animals were analyzed by dyMRI. Gadolinium-DOTA (Dotarem) was used as a contrast agent to detect vessel permeability and contrast agent extravasation, whereas intravascular iron oxide nanoparticles (Endorem) were used to detect partial tumor blood volume. Additionally, vessel density, architecture, diameter, and blood flow velocity were investigated by appropriate methods. Surprisingly, no changes in extravasation occurred under treatment with PTK787/ZK 222584 as compared with the control group, whereas a significant decrease in vessel permeability occurred. Furthermore, an increase in partial blood volume was found in the PTK787/ZK 222584-treated group, although vessel density was reduced as seen by histology. Using the corrosion cast technique, reduction in vessel density was significant but not very pronounced and predominantly attributable to the loss of microvessels only. This finding correlated with a shift to large vessel diameters in the primary tumors of PTK787/ZK 222584-treated animals and with reduction of blood flow velocity in the tumor feeding renal artery. From these findings, we conclude that the treatment with PTK787/ZK 222584 primarily reduces the number of tumor microvessels, accompanied by a hemodynamic dilation of the remaining vessels. This dilation could influence the result of dyMRI such that no change in extravasation or even an increase in partial tumor blood volume could be observed.     

Phase I pharmacokinetic study of the vascular endothelial growth factor receptor tyrosine kinase inhibitor vatalanib (PTK787) plus imatinib and hydroxyurea for malignant glioma

BACKGROUND:

This study determined the maximum tolerated dose (MTD) and dose‐limiting toxicities (DLT) of the oral vascular endothelial growth factor receptor (VEGFR) inhibitor, vatalanib, when administered with imatinib and hydroxyurea on a continuous daily schedule among recurrent malignant glioma patients.

METHODS:

All patients received 500 mg of hydroxyurea twice daily. Imatinib was dosed at 400 mg per day for patients not taking enzyme‐inducing antiepileptic drugs (EIAEDs; stratum A) and at 500 mg twice‐a‐day for patients taking EIAEDs (stratum B). Vatalanib was escalated from 500 mg to 1250 mg twice daily in successive cohorts, independently for each stratum. Pharmacokinetics of each drug were assessed.

RESULTS:

A total of 37 recurrent patients, 34 (92%) with glioblastoma and 3 (8%) with grade 3 malignant glioma, were enrolled. Nineteen patients (51%) were taking EIAEDs. The MTD of vatalanib for all patients was 1000 mg twice‐a‐day. DLTs were hematologic, gastrointestinal, renal, and hepatic. No patients developed intracranial hemorrhage. Concurrent administration of imatinib and hydroxyurea did not affect vatalanib exposure, but EIAEDs decreased vatalanib and imatinib plasma exposures.

CONCLUSIONS:

Vatalanib doses up to 1000 mg twice‐a‐day combined with imatinib and hydroxyurea were well tolerated. Strategies to target tumor blood vessel endothelial cells and pericytes by inhibiting VEGFR and platelet‐derived growth factor, respectively, were safe among recurrent malignant glioma patients and may enhance antiangiogenesis activity. Cancer 2009. © 2009 American Cancer Society.     

Phase 1 study of PTK787/ZK 222584, a small molecule tyrosine kinase receptor inhibitor, for the treatment of acute myeloid leukemia and myelodysplastic syndrome.

PTK787/ZK 222584 (PTK/ZK) is an oral angiogenesis inhibitor targeting vascular endothelial growth factor (VEGF) receptor tyrosine kinases, including VEGFR-1/Flt-1, VEGFR-2/KDR, VEGFR-3/Flt-4, the platelet-derived growth factor receptor tyrosine kinase and the c-kit protein tyrosine kinase. The objective of this Phase I study was to evaluate the safety, tolerability, biologic activity and pharmacologic profile of PTK/ZK administered orally, twice daily, on a continuous dosing schedule in patients with primary refractory or relapsed acute myeloid leukemia (AML), secondary AML, poor-prognosis de novo AML or advanced myelodysplastic syndrome (MDS). Acute myeloid leukemia patients for whom PTK/ZK monotherapy was ineffective could receive PTK/ZK combined with standard induction chemotherapy. Sixty-three patients received PTK/ZK at doses of 500-1000 mg orally b.i.d. Safety and pharmacokinetic data were collected. Responses were evaluated according to standard bone marrow and peripheral blood criteria. At 1000 mg b.i.d., dose-limiting toxicities of lethargy, hypertension, nausea, emesis and anorexia were observed. Other adverse events related to PTK/ZK were dizziness, weakness, fatigue, diarrhea and pruritus; these were generally mild and reversible. Pharmacokinetic data showed that steady state was reached by day 14, there was no accumulation with repeat dosing and there was no significant increase in exposure at steady state beyond the maximum tolerated dose (MTD). Complete remission was observed in five of 17 AML patients treated with PTK/ZK combined with chemotherapy.In conclusion, the MTD of PTK/ZK is 750 mg orally b.i.d. The drug is generally well tolerated and can be given in combination with chemotherapy for patients with MDS and AML.     

Effects of PTK787/ZK 222584, a specific inhibitor of vascular endothelial growth factor receptor tyrosine kinases, on primary tumor, metastasis, vessel density, and blood flow in a murine renal cell carcinoma model

Antiangiogenic therapy is a promising new strategy to inhibit tumor growth and formation of metastases. Vascular endothelial growth factor (VEGF) and its receptors, VEGF-receptor 1 (VEGF-R1; FLT-1) and VEGF-R2 (KDR), have been shown to play a major role in tumor angiogenesis. PTK787/ZK 222584, a specific inhibitor of both VEGF-receptor tyrosine kinases, was investigated for its antitumoral and antiangiogenic activity in a murine renal cell carcinoma model. After intrarenal application of the renal carcinoma cells, mice develop a primary tumor and metastases to the lung and to the abdominal lymph nodes. Daily oral therapy with PTK787/ZK 222584 at a dose of 50 mg/kg resulted in a significant decrease of 61 and 67% in primary tumors after 14 and 21 days, respectively. The occurrence of lung metastases was significantly inhibited at both time points (98% reduction and 78% reduction, respectively). After 14 days, no lymph node metastases developed in the PTK787/ZK 222584-treated group, whereas after 21 days of treatment, the lymph node metastases were reduced by 87%. Vessel density in tumor tissues, detected by immunohistochemistry with an anti-CD31 antibody, was significantly decreased by PTK787/ZK 222584. Using color Doppler imaging ultrasound, significant changes in blood flow in the tumor feeding renal artery were found under treatment with PTK787/ZK 222584. Blood flow changes correlated with changes in vessel density but not with tumor volume. The compound was well tolerated in all in vivo experiments and had no significant effects on body weight or general well-being of the animals. This was in contrast to the animals treated with the antiangiogenic agent TNP-470. s.c. therapy with 30 mg/kg TNP-470 every other day had to be discontinued after 13 days because of animal weight loss (>20%) and ataxia. These results demonstrate that PTK787/ZK 222584 is a potent inhibitor of tumor growth, metastases formation, and tumor vascularization in murine renal cell carcinoma. Furthermore, we have been able to demonstrate that color Doppler imaging ultrasound can be used to measure blood flow to a tumor and that flow correlates with vessel density. Thus, this may be a valuable noninvasive method for monitoring the effects of antiangiogenic agents such as PTK787/ZK 222584 on tumor vasculature.     

Acquired drug resistance to vascular endothelial growth factor receptor 2 tyrosine kinase inhibitor in human vascular endothelial cells

Acquired resistance to antiangiogenic drugs has emerged as a potentially important issue in clinical settings; however, the underlying molecular and cellular mechanism of resistance to vascular endothelial growth factor receptor 2 (VEGFR2) tyrosine kinase inhibitor (TKI) remains largely unclear. We evaluated the cellular characteristics of human umbilical vein endothelial cell (HUVEC) clones, which are resistant to VEGFR2-TKI (Ki8751) to elucidate this mechanism of resistance to antiangiogenic drugs. Resistant HUVEC clones were 10-fold more resistant to VEGFR2-TKI than the parental cells and they exhibited an almost complete absence of VEGF-mediated cellular proliferation. The mRNA expression analysis revealed that expression of VEGFR1, VEGFR2 and VEGFR3 was lower in resistant clones, while that of several angiogenic ligands was increased. The protein expression of VEGFR2 was markedly down-regulated in two (R5 and R6 clone) out of five resistant clones. Focusing on the R5 clone, VEGF stimulation did not increase the phosphorylation of VEGFR2 or the dimerization of VEGFR2. The inhibition of phospho-AKT by VEGFR2-TKI was also weakened more than 10-fold in the R5 clone. Finally, a microarray analysis revealed that some angiogenesis-associated, and some angiogenesis-specific genes, including platelet endothelial cell adhesion molecule 1 (PECAM1)/CD31, homeobox A9 (HOXA9), and endothelial cell-specific molecule 1 (ESM1), were remarkably down-regulated in all the resistant clones compared with the parental cells. HUVEC clones resistant to VEGFR2-TKI exhibited down-regulation of VEGFR2, a decreased signal response to VEGF stimulation, and the loss of vascular endothelial markers. These results strongly suggest that an escape from VEGFR2 signaling-dependency is one of the cellular mechanisms of resistance to VEGFR2-TKI in vascular endothelial cells.     

ZD6474, a novel tyrosine kinase inhibitor of vascular endothelial growth factor receptor and epidermal growth factor receptor, inhibits tumor growth of multiple nervous system tumors.

PURPOSE: Primary central nervous system (CNS) tumors represent a diverse group of tumor types with heterogeneous molecular mechanisms that underlie their formation and maintenance. CNS tumors depend on angiogenesis and often display increased activity of ErbB-associated pathways. Current nonspecific therapies frequently have poor efficacy in many of these tumor types, so there is a pressing need for the development of novel targeted therapies. EXPERIMENTAL DESIGN: ZD6474 is a novel, orally available low molecular weight inhibitor of the kinase activities associated with vascular endothelial growth factor receptor-2 and epidermal growth factor receptor. We hypothesized that ZD6474 may provide benefit in the treatment of several CNS tumor types. RESULTS: In mice bearing established s.c. tumor xenografts of CNS tumors (malignant glioma and ependymoma) or rhabdomyosarcoma, a limited course of ZD6474 treatment produced significant tumor growth delays and a high rate of partial tumor regression in most models examined. Mice with i.c. malignant glioma xenografts treated with ZD6474 experienced a significant prolongation of survival. Tumors from mice treated with ZD6474 displayed a lower proliferative index and disrupted tumor vascularity. Notably, some of these models are insensitive to low molecular weight kinase inhibitors targeting only vascular endothelial growth factor receptor-2 or epidermal growth factor receptor functions, suggesting that the combined disruption of both epidermal growth factor receptor and vascular endothelial growth factor receptor-2 activities may significantly increase tumor control. CONCLUSIONS: In conclusion, ZD6474 shows significant activity against xenograft models of several primary human CNS tumor types. Consideration for clinical development in this disease setting seems warranted.     

Biomarkers for assessment of pharmacologic activity for a vascular endothelial growth factor (VEGF) receptor inhibitor, PTK787/ZK 222584 (PTK/ZK): translation of biological activity in a mouse melanoma metastasis model to phase I studies in patients with advanced colorectal cancer with liver metastases

PTK/ZK is a novel, oral angiogenesis inhibitor that specifically targets all 3 vascular endothelial growth factor (VEGF) receptor tyrosine kinases and is currently in phase III clinical trials. In early clinical trials, PTK/ZK demonstrated a dose-dependent reduction in tumor vascular parameters as measured by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and an acute increase in plasma VEGF levels. The reduction in tumor vascularity was significantly correlated with improved clinical outcome in patients with advanced colorectal cancer and liver metastases. To assess the predictive value of a mouse model of tumor metastases, comparisons were performed for the biological activity of PTK/ZK in the mouse model and in patients with liver metastases in the clinical phase I trials. An orthotopic, syngeneic mouse model was used: C57BL/6 mice injected in the ear with murine B16/BL6 melanoma cells which metastases to the cervical lymph-nodes. The primary tumor and spontaneous metastases express VEGF and VEGF receptors and respond to treatment with VEGFR tyrosine kinase inhibitors. PTK/ZK was administered orally, with assesments by DCE-MRI of the metastases and plasma VEGF taken predose and at 3 days posttreatment and efficacy determined at 7 days posttreatment. Dose-ranging studies in naive mice provided preclinical pharmacokinetic data, while two dose-escalation phase I studies provided clinical pharmacokinetic data. An exposure–response relationship was observed both for mouse metastases (measured as % tumor weight treated/control) and for human liver metastases (measured as % regression). In the B16/BL6 model, the active dose of 50 mg/kg PTK/ZK yielded 62.4 (± 16.0) h μM plasma exposure, which is comparable to the plasma area under the concentration time curve (AUC) achieved by the 1000 mg dose of PTK/ZK used in clinical trials. At this exposure level in clinical trials, DCE-MRI showed a reduction in the area under the enhancement curve (IAUC) to 47% of baseline. At a similar exposure in the PTK/ZK-treated mice, a reduction in IAUC to 75% of baseline was observed. Furthermore, at doses of 50 mg/kg PTK/ZK and above, an increase in plasma VEGF level 10 h after drug administration was observed in mice which was consistent with findings from the clinical trials. In conclusion, the preclinical pharmacodynamics of PTK/ZK correlate well with clinical activity in phase I trials over comparable exposures to the drug. Thus, data from this preclinical model proved to be consistent with and thus predictive of the biologic effects of PTK/ZK in phase I/II clinical trials.     

A phase II trial of PTK787/ZK 222584 in recurrent or progressive radiation and surgery refractory meningiomas

When surgery and radiation are no longer treatment options, salvage systemic therapy has been used for recurrent meningiomas with little compelling evidence to suggest effectiveness. Patients with surgery and radiation refractory recurrent meningiomas were treated with the oral multifunctional tyrosine kinase inhibitor PTK787/ZK 222584 (PTK787) at a dose of 500 mg twice a day. Each treatment cycle was 4 weeks with MRI done every 8 weeks. Twenty-five patients (14 men; 11 women) with a median age of 59 years and KPS of 80 were treated. Meningioma WHO Grade was I in 2 patients, II in 14 patients and III in 8 patients; 1 patient had a hemangiopericytoma. All patients had prior surgery, external beam radiation therapy or radiosurgery and 11 patients prior systemic chemotherapy. Median number of cycles of PTK 787 administered was 4 (range <1–22). Best response in the 22 evaluable patients was stable disease in 15 (68.2 %). Predominant PTK787 related toxicities included fatigue (60 %), hypertension (24 %) and elevated transaminases (24 %). Grade II patients had a progression free survival (PFS)-6 of 64.3 %, a median PFS of 6.5 months and an overall survival (OS) of 26.0 months; grade III patients had a PFS-6 of 37.5 %, median PFS of 3.6 months and OS 23 months. PTK787 was modestly toxic at the dose of 500 mg administered twice per day. Activity as determined by PFS-6 suggests that targeting PDGF/VEGF pathway warrants further investigation.     

Dynamic contrast-enhanced magnetic resonance imaging as a biomarker for the pharmacological response of PTK787/ZK 222584, an inhibitor of the vascular endothelial growth factor receptor tyrosine kinases, in patients with advanced colorectal cancer and liver metastases: results from two phase I studies.

PURPOSE: PTK787/ZK 222584 (PTK/ZK), an orally active inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, inhibits VEGF-mediated angiogenesis. The pharmacodynamic effects of PTK/ZK were evaluated by assessing changes in contrast-enhancement parameters of metastatic liver lesions using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in patients with advanced colorectal cancer treated in two ongoing, dose-escalating phase I studies. PATIENTS AND METHODS: Twenty-six patients had DCE-MRI performed at baseline, day 2, and at the end of each 28-day cycle. Doses of oral PTK/ZK ranged from 50 to 2000 mg once daily. Tumor permeability and vascularity were assessed by calculating the bidirectional transfer constant (Ki). The percentage of baseline Ki (% of baseline Ki) at each time point was compared with pharmacokinetic and clinical end points. RESULTS: A significant negative correlation exists between the % of baseline Ki and increase in PTK/ZK oral dose and plasma levels (P =.01 for oral dose; P =.0001 for area under the plasma concentration curve at day 2). Patients with a best response of stable disease had a significantly greater reduction in Ki at both day 2 and at the end of cycle 1 compared with progressors (mean difference in % of baseline Ki, 47%, P =.004%; and 51%, P =.006; respectively). The difference in % of baseline Ki remained statistically significant after adjusting for baseline WHO performance status. CONCLUSION: These findings should help to define a biologically active dose of PTK/ZK. These results suggest that DCE-MRI may be a useful biomarker for defining the pharmacological response and dose of angiogenesis inhibitors, such as PTK/ZK, for further clinical development.     

Role of B-cell-activating factor in adhesion and growth of human multiple myeloma cells in the bone marrow microenvironment

Recent studies have underscored the role of B-cell-activating factor (BAFF), a member of the tumor necrosis factor superfamily, in promoting the survival of malignant B cells, including human multiple myeloma. We here characterized the functional significance of BAFF in the interaction between multiple myeloma and bone marrow stromal cells (BMSC) and further defined the molecular mechanisms regulating these processes. BAFF is detected on BMSCs derived from multiple myeloma patients as evidenced by flow cytometry. BAFF secretion is 3- to 10-fold higher in BMSCs than in multiple myeloma cells, and tumor cell adhesion to BMSCs augments BAFF secretion by 2- to 5-fold, confirmed by both ELISA and immunoblotting. Adhesion of MM1S and MCCAR multiple myeloma cell lines to KM104 BMSC line transfected with a luciferase reporter vector carrying the BAFF gene promoter (BAFF-LUC) significantly enhanced luciferase activity, suggesting that nuclear factor-kappaB (NF-kappaB) activation induced by multiple myeloma adhesion to BMSCs mediates BAFF up-regulation. Moreover, BAFF (0-100 ng/mL) increases adhesion of multiple myeloma lines to BMSCs in a dose-dependent manner; conversely, transmembrane activator and calcium modulator and cyclophylin ligand interactor-Ig or B-cell maturation antigen/Fc blocked BAFF stimulation. Using adenoviruses expressing dominant-negative and constitutively expressed AKT as well as NF-kappaB inhibitors, we further showed that BAFF-induced multiple myeloma cell adhesion is primarily mediated via activation of AKT and NF-kappaB signaling. Importantly, BAFF similarly increased adhesion of CD138-expressing patient multiple myeloma cells to BMSCs. These studies establish a role for BAFF in localization and survival of multiple myeloma cells in the bone marrow microenvironment and strongly support novel therapeutics, targeting the interaction between BAFF and its receptors in human multiple myeloma.     

Adherence of multiple myeloma cells to bone marrow stromal cells upregulates vascular endothelial growth factor secretion: therapeutic applications.

Increased angiogenesis has recently been recognized in active multiple myeloma (MM). Since vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are two key mediators of angiogenesis, we characterized the production of VEGF, b-FGF and interleukin-6 (IL-6) (a MM growth and survival factor) in MM cell lines and Epstein-Barr virus (EBV) transformed B cell lines from MM patients, patient MM cells, as well as bone marrow stromal cells (BMSCs) from normal healthy donors and MM patients. We detected secretion of VEGF, but no bFGF and IL-6, in MM cell lines (MM.1S, RPMI 8226 and U266); EBV transformed B cell lines from MM patients (IM-9, HS-Sultan and ARH77); MM cell lines resistant to doxorubicin (RPMI-DOX40), mitoxantrone (RPMI-MR20), melphalan (RPMI-LR5) and dexamethasone (MM.1R); and patient MM cells (MM1 and MM2). BMSCs from MM patients and normal donors secreted VEGF, b-FGF and IL-6. Importantly, when MM cells were adhered to BMSCs, there was a significant increase in VEGF (1.5- to 3.1-fold) and IL-6 (1.9- to 56-fold) secretion. In contrast, the bFGF decreased in co-cultures of BMSCs and MM cells. Paraformaldehyde fixation of BMSCs or MM cells prior to adhesion revealed that VEGF was produced both from BMSCs and MM cells, though it may come primarily from BMSCs in some cultures. IL-6 was produced exclusively in BMSCs, rather than MM cells. Moreover, when MM cells were placed in Transwell insert chambers to allow their juxtaposition to BMSCs without cell to cell contact, induction of VEGF and IL-6 secretion persisted, suggesting the importance of humoral factors. Addition of exogenous IL-6 (10 ng/ml) increased VEGF secretion by BMSCs. Conversely, VEGF (100 ng/ml) significantly increased IL-6 secretion by BMSCs. Moreover, anti-human VEGF (1 microg/ml) and anti-human IL-6 (10 microg/ml) neutralizing antibodies reduced IL-6 and VEGF secretion, respectively, in cultures of BMSCs alone and co-cultures of BMSCs and MM cells. Finally, thalidomide (100 microM) and its immunomodulatory analog IMiD1-CC4047 (1 microM) decreased the upregulation of IL-6 and VEGF secretion in cultures of BMSCs, MM cells and co-cultures of BMSCs with MM cells. These data demonstrate the importance of stromal-MM cell interactions in regulating VEGF and IL-6 secretion, and suggest additional mechanisms whereby thalidomide and IMiD1-CC4047 act against MM cells in the BM millieu.