Current studies with PTK787, an oral inhibitor of vascular endothelial growth factor in colorectal cancer.
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Caspofungin acetate is the first member of the novel echinocandin class of antifungal drugs to be marketed in the United States. It has recently been approved for use in patients with invasive aspergillosis who are refractory to or intolerant of conventional therapy. Accordingly, its safety profile is particularly important to review. The safety and tolerability of caspofungin have been examined in 623 persons, including 295 patients who received >/= 50 mg/day for at least one week in clinical studies. In the 263 patients, given caspofungin in randomized double-blind active-control trials to date, there have been no serious clinical or laboratory drug-related adverse events; caspofungin was discontinued in only 2% of these patients because of drug-related adverse experiences. Caspofungin may have potentially important drug interactions with cyclosporine and tacrolimus.
A World Health Organization (WHO) advisory committee meeting in Geneva at the end of last month approved phase III trials for HIV vaccines in developing countries. What is the justification for this decision?
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PURPOSE: To review the current state of knowledge of the treatment of primary (idiopathic) generalized epilepsy syndromes based on the efficacy results of clinical trials, to highlight obstacles in the design of these trials, and to suggest solutions for future research. METHODS: Published reports of controlled clinical trials, as well as large or significant uncontrolled trials of treatments for these syndromes, were reviewed. Trials were selected for discussion based on their importance or their illustration of design issues. RESULTS: Only a few randomized, controlled trials of therapy for these syndromes exist. Conclusions based on this Class I data include efficacy in absence epilepsies for ethosuximide, valproate, and lamotrigine, and for eight drugs for primary generalized tonic-clonic seizures. Many commonly accepted therapeutic strategies are not based on formal data. No controlled data exist for uncommon syndromes. CONCLUSIONS: More clinical trials of therapies for primary generalized epilepsies are needed. To overcome design obstacles, better funding, multicenter cooperation, inclusion of children, study designs requiring fewer patients, equivalent-control designs, use of EEG and video seizure counting, and better syndrome identification will be required.
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Antisense oligonucleotides are short DNA sequences designed to modulate the information transfer from gene to protein. Sequence-related hybridisation with the mRNA of a specific protein results in selective inhibition of gene expression and downregulation of protein expression. This allows the study of gene function and therapy on a molecular level. Antisense oligonucleotide inhibitors can be designed directly from genomic sequence information by simply making the reversed complement of the desired sequence. In this review, we focus on the mechanisms of action of antisense oligonucleotides and summarize the progress in urological antisense therapy. The ability to inhibit individual gene expression with antisense oligonucleotides has been promising in preclinical cancer models. Current clinical studies test antisense compounds targeted against various cancer related genes. Although some of these studies comprise patients with urological tumors, such as advanced prostate cancer, experimental antisense therapy in urology is still in its infancy.
Hormone-refractory prostate cancer is diagnosed with increasing incidence and has become a growing challenge for urologists. The improved understanding of the tumor biological mechanisms of the hormone-refractory state has led to innovative therapeutic developments in the field of hormonal and cytotoxic therapies. Recently, two large randomized Phase III trials with docetaxel-based chemotherapy were able to show prolonged survival and a positive influence on pain and quality of life, establishing a new standard of care for these patients. Moreover, bisphosphonates seem to have positive influence on selected patients. In the growing field of molecular targeted therapy, first trials with compounds, such as tyrosine kinase inhibitors, anti-sense oligonucleotides, angiogenesis inhibitors and endothelin receptor antagonists, show promising results in the treatment of patients with hormone-refractory prostate cancer.
BACKGROUND: Patients with head and neck tumors are treated with palliative chemotherapy in case of the detection of distant metastases or local recurrence without the option of surgical therapy or radiation. Alongside 5-fluorouracil (5-FU) in combination with cisplatin or carboplatin, taxanes, gemcitabine and vinorelbine as well as monoclonal antibodies or small molecule tyrosine kinase inhibitors have been used. METHODS: This review analyses the published literature of the past 15 years, including selected abstracts with view to response rate, overall survival and adverse effects. RESULTS: 5-FU plus cisplatin or carboplatin can still be considered as standard treatment, achieving response rates of 20-30 %. The addition of taxanes increases the objective response rate but adds remarkable toxicity to the treatment protocol. Phase III studies demonstrate higher response rates but fail to demonstrate a significant increase of the overall survival after polychemotherapy as compared to monotherapy protocols. Thus, patients with a reduced performance can be treated with monotherapy. In case of disease progression after cisplatin-containing chemotherapy further treatment should only be offered to selected patients. For this situation, platin-free chemotherapy protocols containing taxanes, gemcitabine or vinorelbine seem promising. Recent studies with monoclonal antibodies or small molecule tyrosine kinase inhibitors report on a response rate of 10-20 %. CONCLUSION: The use of new drugs increases the response rate and amends the side effects of the chemotherapy. However, phase III studies documenting an improved overall survival are lacking. Targeted therapies broaden the therapeutic armament, and possibly, EGFR inhibition will help to overcome chemotherapy resistance in the future.
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OBJECTIVE: Our objective was to describe the pharmacokinetics and pharmacodynamics of topotecan in patients. METHODS: Data were pooled from 9 clinical trials. Topotecan, as a single-agent therapy, was administered as a daily 30-minute intravenous infusion for 5 days on a 3-week cycle. Doses of 0.2 to 2.0 mg/m(2) were studied; concentration and neutropenic event data were obtained on multiple occasions. The pharmacokinetics were characterized with use of hierarchical nonlinear regression. The relationship between severity of neutropenia and exposure was characterized with use of logistic regression. RESULTS: The pharmacokinetics of topotecan were described with a linear 2-compartment model. Compromised renal function, low body weight, and poor Eastern Cooperative Oncology Group performance status were determinants of lower clearance, resulting in elevated exposure. Application of covariates reduced interpatient variability in clearance. Logistic regression showed that topotecan area under the concentration-time curve from 0 to 24 hours was predictive of the severity of neutropenia; the only other significant covariate was the number of courses of previous treatment with platinum-based regimens. CONCLUSIONS: Patients with compromised renal function, low body weight, or poor performance status had low topotecan clearance. Patients with high topotecan AUC had an increased probability of experiencing severe neutropenia, which was greater if the patient had been pretreated with platinum-based agents. The use of covariates to individualize dose would result in less variability in exposure, reducing the likelihood of severe neutropenia and potentially improving treatment benefit.
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The clinical development process can be viewed as a succession of trials, possibly overlapping in calendar time. The design of each trial may be influenced by results from previous studies and other currently proceeding trials, as well as by external information. Results from all of these trials must be considered together in order to assess the efficacy and safety of the proposed new treatment. Meta-analysis techniques provide a formal way of combining the information. We examine how such methods can be used in combining results from: (1) a collection of separate studies, (2) a sequence of studies in an organized development program, and (3) stages within a single study using a (possibly adaptive) group sequential design. We present two examples. The first example concerns the combining of results from a Phase IIb trial using several dose levels or treatment arms with those of the Phase III trial comparing the treatment selected in Phase IIb against a control This enables a "seamless transition" from Phase IIb to Phase III. The second example examines the use of combination tests to analyze data from an adaptive group sequential trial.
Pegylated liposomal doxorubicin (Doxil, Caelyx) is a formulation of doxorubicin in poly(ethylene glycol)-coated (stealth) liposomes with a prolonged circulation time and unique toxicity profile. We review the preclinical and clinical pharmacology as well as recent clinical data obtained in specific cancer types. Doxil liposomes retain the drug payload during circulation and accumulate preferentially in tissues with increased microvascular permeability, as often is the case of tumors. Doxil toxicity profile is drastically different from that of doxorubicin, and is characterized by dominant and dose-limiting mucocutaneous toxicities, mild myelosuppression, minimal alopecia, and no apparent cardiac toxicity. Although the single maximum tolerated dose (MTD) of Doxil is actually lower than that of conventionally administered doxorubicin, the cumulative MTD dose of Doxil may be substantially greater than that of free doxorubicin. Doxil is probably one of the most active agents in AIDS-related Kaposi's sarcoma and has a definite role in management of recurrent ovarian cancer. The potential of Doxil in the treatment of other cancer types and the opportunities it offers in combination with other drugs and therapeutic modalities are under active investigation.
The design of clinical trials for new antiretroviral agents poses unique challenges, given the availability of highly active antiretroviral therapy (HAART). These challenges include the selection of appropriate populations, the methods used to partition the effects of the study drug under observation from those of the other concurrently administered medications in early studies, performance of dose-ranging studies for disease states in which suboptimal drug exposure may lead to the development of viral resistance that limits future treatment options, and the need to fulfill the obligations of international regulatory agencies. Throughout, science and ethics are tightly woven elements in study designs for antiretroviral drug trials. Fast-track drug approval status and successful lobbying by advocates for patients with acquired immunodeficiency syndrome aimed at the US Food and Drug Administration, the National Institutes of Health, the Centers for Disease Control and Prevention, university teaching centers, pharmaceutical companies, and members of Congress undoubtedly contributed to the development and swift regulatory approvals of the 17 antiretroviral medications now available in the United States for the treatment of human immunodeficiency virus infection.
One of the major expectations from the use of humanized monoclonal antibodies in cancer therapy has been that of exploiting the specificity and sensitivity of the immune system to achieve selective therapeutic effects devoid of the often severe toxicity caused by chemotherapy. The tolerability of trastuzumab (Herceptin) as it emerged from the trials where the drug was used as a single agent or in combination with chemotherapy largely confirmed that expectation. Adverse events most frequently encountered include mild-to-moderate, transient effects related to administration of the first dose of trastuzumab. The incidence of severe or serious adverse effects attributable to trastuzumab was low. However, the occurrence of cardiac toxicity that was unexpectedly high, especially in patients previously or concomitantly treated with anthracyclines, could not be predicted on the basis of the putative mechanism of action of the antibody. The safety profile of trastuzumab is discussed here with a particular focus on cardiotoxicity and the issues relating to patient management during trastuzumab therapy.