Myoclonus is defined as shock-like, brief involuntary abnormal movements in muscle jerking caused by external stimuli; and it arises from progressive myoclonus epilepsy, post-anoxic encephalopathy and Alzheimer's disease, causing disabling symptoms. It is a rare syndrome but very difficult to control. Piracetam (2-oxo-1-pyrrolidineacetamide, Myocalm®) was developed more than 30 years ago as a cyclic derivative of γ-aminobutyric acid (GABA) ; it has been used in European countries for the treatment of memory loss and other cognitive defects in patients. Some reports have suggested that piracetam has anti-myoclonus activities, but the mechanisms of myoclonus are not well-identified, and thus there have been few preclinical studies on piracetam for the treatment of myoclonus. We investigated the effect of piracetam and clonazepam, an anti-epileptic drug, on high dosage urea-induced myoclonus using an electromyogram in rats. The incidence of myoclonus induced by urea 4.5 g/kg (i.p.) was significantly reduced by piracetam at 300 mg/kg (i.p.) and by clonazepam at 0.3 mg/kg (p.o.). The coadministration of piracetam 100 mg/kg (i.p.) and clonazepam at 0.03-0.1 mg/kg (p.o.) significantly reduced the incidence of myoclonus, although separate administration was not effective. After oral administration of piracetam, it is rapidly and completely absorbed and excreted almost unchanged in the urine; however, it does show a little binding to human serum protein. Repeated oral administration of piracetam for 7 days in phase-I trials did not show any accumulation of the drug. In the placebo-controlled double-blind crossover trial of piracetam conducted in the UK, there was a significant improvement in cortical myoclonus. In phase-II trials, piracetam inhibited myoclonus and showed an improvement in the quality of life (QOL) of the patients. These results show that piracetam has a beneficial use in clinics for severe myoclonus patients when it is combined with anti-epileptic drugs, demonstrating an improvement in the myoclonus and QOL of patients.

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Vinorelbine (VNR) is a new vinca alkaloid derivative semisynthesized by Potier et al. The antitumor activity of VNR was superior to other vinca alkaloid antitumor agents, and the neuro-toxicity of VNR was weaker than those of other vinca alkaloids. In nude mice xenografted human tumor models, VNR showed antitumor activity against eight of eleven tumor models (non-small cell lung cancer: 4/4, breast cancer: 2/3, colon cancer: 0/2, stomach cancer: 2/2). Especially, VNR showed tumor-regressive activity against LC-6 non-small cell lung cancer and MX-1 breast cancer. The antitumor activity of VNR against non-small cell lung cancer was superior to that of vindesine (VDS), which had been one of the key drugs of non-small cell lung cancer in the clinic. In combination chemotherapy, VNR plus cisplatin (CDDP) was better than VDS plus CDDP, which had been one of the standard regimens of non-small cell lung cancer chemotherapy. The potent antitumor effect of VNR with minor neurotoxicity was explained by VNR having stronger activity on mitotic microtubules than axonal microtubules. It was supposed that less activity of VNR against mitotic microtubules would be related to different composition of microtubule-associated TAU isoforms in the two types of microtubules. In non-small cell lung cancer, VNR resulted in a significantly higher response rate than VDS. In combination with CDDP, VNR resulted in longer survival than VDS with a significant log-rank test. In advanced breast cancer, VNR resulted in a high response rate in 1st line and 2nd line treatment. VNR is effective in combination with chemotherapeutic agents such as anthracyclin, fluorouracil and Taxol. In Japan, the clinical trial in breast cancer is now ongoing.

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It is now known that the blockade of 5-HT₂ receptors can ameliorate the negative symptoms of schizophrenia and extrapyramidal side effects (EPS) associated with antipsychoitc treatments. Perospirone hydrochloride (perospirone), which was identified as a novel serotonin-dopamine antagonist (SDA)-type antipsychotic agent in 1987 by Sumitomo Pharmaceuticals, possesses high affinities both for dopamine 5-HT₂ and D₂ receptors. Perospirone, like conventional antipsychotics, significantly inhibited various behaviors induced by dopaminergic hyperactivation. Perospirone also produced a significant improvement in animal models of the negative symptoms and mood disorders, where the conventional antipsychotics were unaffected. In addition, perospirone was weaker than the conventional antipsychotics (e.g., haloperidol) in inducing EPS signs (e.g., catalepsy and bradykinesia), suggesting that the drug has an atypical antipsychotic property. A recent double-blind study with schizophrenia patients demonstrated that perospirone was comparative with haloperidol in improving the positive symptoms, but was significantly superior to haloperidol against the negative symptoms. Furthermore, the extrapyramidal score in patients with perospirone treatment was lower that those with haloperidol treatment. These findings suggested that perospirone acts as an antagonist both for 5-HT₂ and D₂ receptors and has broader clinical efficacy and lower EPS liability than haloperidol in schizophrenia treatment.

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The bone morphogenetic proteins (BMPs) are members of the TGF-β gene superfamily, a large family of secreted signaling molecules. When implanted locally to animals with appropriate carriers, recombinant human BMP-2 (rhBMP-2) and some other members of BMPs reproduced very potent, ectopic bone forming activity. In vitro, rhBMP-2 is shown to induce differentiation of mesenchymal stem cells into osteoblast and chondroblast cells and to prevent the former cells from differentiating into cell types other than the latter cells. Several BMP (IA, IB and II) receptors, which belong to the TGF-β receptor family of serine/ threonine kinases, have also been cloned and characterized. The intracellular signal transduction and transcriptional factors associating with BMP receptors are also being investigated. For clinical applications, we have developed suitable carriers for rhBMP-2, which are biocompatible, biodegradable and non-immunogenic. We have also shown that rhBMP-2, combined with such carriers, induces significant bone formation in various kinds of bone defect models that mirror clinical applications in rodents and larger animals, including non-human primates. These preclinical studies have proved that the bone induced by rhBMP-2 seemed to behave as morphologically and mechanically normal. Clinical trials are underway to determine its usefulness in orthopedic and oral and maxillofacial fields.

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Pharmacogenomics is defined as identification of loci which are involved in determining the responsiveness and distinguishing responders and non-responders to a given drug. Genome sequensing, transcriptome and proteome analysis are of particular significance in pharmacogenomics. Sequencing is used to locate polymorphisms, and monitoring of gene expression can provide clues about the genomic response to disease and treatment. The transcriptome analysis can be done by methods of random cDNA sequencing (expressed sequence tag project, body map project, serial analysis of gene expression, etc.), mRNA display (differential display, fluorescent differential display, RNA arbitraly primed PCR, molecular indexing, gene expression fingerprinting, etc.) and differential hybridization (cDNA high density filter, cDNA microarray, oligomicrochip, etc.). We describe the principle and application of trancriptome analysis in pharmacogenomics, especially differential display and cDNA microarray. We used transcriptome analysis to identify therapeutic target genes by studying the change of gene expression in animal models of oxidative stress and hypoxia and found novel drug target candidates through this pharmacogenomic strategy.

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