Cloretazine (VNP40101M) is a newly synthesized alkylating agent belonging to a novel class of alkylating agents called 1,2-bis(sulfonyl)hydrazines. Agents that belong to this class do not produce ...vinylating and chloroethylating species, and hence this class of alkylating agents is thought to have minimal systemic toxicity. Cloretazine produces two short-lived active species: 1,2-bis(methylsulfonyl)-1-(2-chloroethyl) hydrazine (a chloroethylating species) and a thiophilic carbamoylating methylisocyanate species. The chloroethylating species preferentially produces lesions at the O(6) position of guanine. The methylisocyanate species may inhibit O(6)-alkylguanine-DNA alkyltransferase, an important mechanism of resistance against alkylating agents. The purpose of this study was to determine the efficacy and tolerability of Cloretazine in patients with recurrent glioblastoma multiforme. The basis for the determination of efficacy was the proportion of patients alive without evidence of disease progression six months after initiation of treatment. Patients with recurrent glioblastoma multiforme received Cloretazine (300 mg/m(2)) intravenously every six weeks. Radiographic response, survival data, and toxicity were assessed. Thirty-two patients were enrolled. Median age was 56 years; 24 patients (75%) were men. At six months, two patients were alive and progression free, so the six-month progression-free survival (PFS) was 6%. The median PFS was 6.3 weeks. There were no objective radiographic responses. Twelve patients had stable disease for at least one cycle, but only two patients received more than three cycles. Nine patients experienced grade 4 thrombocytopenia and three patients experienced grade 4 neutropenia. Cloretazine administered every six weeks was relatively well tolerated, although this schedule has insignificant activity for patients with recurrent glioblastoma multiforme.
Identifying the role of axonal injury in the development of permanent, irreversible neurologic disability is important to the study of central nervous system (CNS) demyelinating diseases. Our ...understanding of neurologic dysfunction in demyelinating diseases and the ability to assess therapeutic interventions depends on the development of objective functional assays that can non-invasively measure axonal loss. In this study, we demonstrate in a murine model of progressive CNS demyelination that assessment of the hindlimb width of stride provides a powerful indicator of axonal loss and can dissociate between deficits induced by demyelination versus axonal loss.
Cloretazine (VNP40101M) is a newly synthesized alkylating agent belonging to a novel class of alkylating agents called 1,2-bis(sulfonyl)hydrazines. Agents that belong to this class do not produce ...vinylating and chloroethylating species, and hence this class of alkylating agents is thought to have minimal systemic toxicity. Cloretazine produces two short-lived active species: 1,2-bis(methylsulfonyl)-1-(2-chloroethyl) hydrazine (a chloroethylating species) and a thiophilic carbamoylating methylisocyanate species. The chloroethylating species preferentially produces lesions at the O
6
position of guanine. The methylisocyanate species may inhibit O
6
-alkylguanine-DNA alkyltransferase, an important mechanism of resistance against alkylating agents. The purpose of this study was to determine the efficacy and tolerability of Cloretazine in patients with recurrent glioblastoma multiforme. The basis for the determination of efficacy was the proportion of patients alive without evidence of disease progression six months after initiation of treatment. Patients with recurrent glioblastoma multiforme received Cloretazine (300 mg/m
2
) intravenously every six weeks. Radiographic response, survival data, and toxicity were assessed. Thirty-two patients were enrolled. Median age was 56 years; 24 patients (75%) were men. At six months, two patients were alive and progression free, so the six-month progression-free survival (PFS) was 6%. The median PFS was 6.3 weeks. There were no objective radiographic responses. Twelve patients had stable disease for at least one cycle, but only two patients received more than three cycles. Nine patients experienced grade 4 thrombocytopenia and three patients experienced grade 4 neutropenia. Cloretazine administered every six weeks was relatively well tolerated, although this schedule has insignificant activity for patients with recurrent glioblastoma multiforme
In clinical trials thus far, single-targeted kinase inhibitors have shown only limited success in demonstrating survival benefits in cancer. This has led to the development of multitargeted kinase ...inhibitors capable of disrupting various mitogenic pathways in both cancer cells and associated vasculature. Vandetanib is a novel multitargeted kinase inhibitor exhibiting potent activity against vascular endothelial growth factor receptor-2 (VEGFR-2; kinase insert domain-containing receptor KDR) and, to a lesser extent, epidermal growth factor receptor (EGFR) and RET kinase. Vascular endothelial growth factor (VEGF) and VEGFR-2 play a pivotal role in regulating angiogenesis and vascular permeability in cancers. In addition to its antiangiogenic effects, vandetanib acts against EGFR, which is overexpressed or mutated in several solid tumors. Furthermore, vandetanib exerts activity against oncogenic RET kinase, the overexpression of which is common in medullary and papillary thyroid carcinomas. Therefore, the multitargeted kinase inhibitor vandetanib represents a new approach, targeting both tumor cells and tumor-associated endothelial cells. Preclinical studies of vandetanib have demonstrated antitumor efficacy against multiple human cancer xenografts in subcutaneous, orthotopic and metastatic models. Phase I clinical trials have demonstrated that vandetanib is well tolerated. Common adverse events included rash, diarrhea and asymptomatic QTc prolongation. Phase II clinical studies in patients with non-small-cell lung cancer have shown promising results, employing vandetanib as both monotherapy and in combination with docetaxel. Phase II studies in other cancers have likewise been initiated. This review summarizes preclinical and clinical studies of vandetanib for the treatment of cancers.
High-Grade Astrocytomas Sathornsumetee, Sith; Reardon, David A.
Primary Central Nervous System Tumors
Book Chapter
High-grade astrocytomas (HGAs) are the most common adult primary malignant brain tumor, which include anaplastic astrocytoma (AA; World Health Organization WHO grade III) and glioblastoma multiforme ...(GBM; WHO grade IV). Although HGAs represent an overall uncommon cancer, they are associated with morbidity and high mortality. Despite state-of-the-art multimodality treatments, the median survival of GBM patients is 12–15 months, whereas that of AA is 2–3 years 1. Current treatments for HGA include surgery, radiation, and chemotherapy. Temozolomide, an oral alkylating chemotherapy, has been approved for newly diagnosed GBM and recurrent AA. It offers significant, albeit modest, survival benefit for unselected HGA patients.
Given the marked upregulation of angiogenesis in glioblastoma, the integration of anti-angiogenic agents into treatment approaches is a highly attractive consideration. Preclinical data support an ...anti-tumor benefit with anti-angiogenic agents in GBM models. However, translation of these agents into the clinic was initially tempered by concern that anti-angiogenics may be associated with severe complications in brain tumor patients including hemorrhages and strokes. Extensive clinical experience to date provides reassurance that such complications are rare and that anti-angiogenics can be safely administered to brain tumor patients. Furthermore, clinical trials conducted among recurrent GBM patients using either bevacizumab, a humanized monoclonal antibody against the primary mediator of tumor angiogenesis, vascular endothelial growth factor (VEGF), or VEGF-receptor tyrosine kinase inhibitors such as cediranib, demonstrate encouraging evidence of anti-tumor benefit. In particular, durable radiographic responses observed among recurrent GBM patients were sufficiently frequent to lead to accelerated approval by the U.S. Food and Drug Administration for bevacizumab in May, 2009. Ongoing efforts are evaluating additional strategies to augment the anti-tumor benefit of anti-angiogenic agents for recurrent patients as well as the safety and efficacy of these agents among newly diagnosed GBM patients.
Glial neoplasms represent 0.5-1% of all cancers in most Western countries. Malignant gliomas are among the most devastating cancers, leading to death in most cases. They present unique challenges due ...to their location, aggressive biological behavior and diffuse infiltrative growth. Notwithstanding the development of new surgical and radiation techniques in the last thirty years, a cure for malignant gliomas remains elusive. In this article, we will review the standard and new therapies used for malignant gliomas. As standard therapies, surgery, radiation therapy and systemic chemotherapy, are in a continuous process of evolution. Multiple chemotherapies have been used in malignant gliomas, as single agents, in combination, or with different modes of administration, including high-dose chemotherapy with stem cell rescue and intra-arterial chemotherapy. The last decade has been noticeable for the advent of a better understanding of the biology of malignant gliomas. This has stimulated active research in multiples areas and the advent of new treatment strategies. Techniques to circumvent the resistance mechanisms to chemotherapy have been evaluated, tyrosine kinase inhibitors have shown activity in malignant primary brain tumors and radioimmunotherapy remains an area of active research. In this article, we review the past, present and future treatments of malignant gliomas with a special interest on chemotherapy, resistance mechanisms and tyrosine kinase inhibitors.
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