New strategies for cell type-specific delivery need to be developed if RNA interference is to realize its full therapeutic potential. One possible approach is the use of aptamers to deliver siRNAs selectively to tumor cells with appropriate antigens displayed on the surface. We used an aptamer that binds specifically to PSMA, a cell surface glycoprotein found in abundance on prostate cancer cells, and joined its 3' end to a siRNA specific for Eukaryotic Elongation Factor 2 mRNA (EEF2). This is an attractive target for cancer therapy because inhibiting EEF2 causes the rapid arrest of protein synthesis, inducing apoptosis and leading ultimately to cell death. In order to enhance the therapeutic efficacy of the aptamer-siRNA, we increased the valency of the construct by rational design. Two anti-PSMA aptamers were designed such that each binding sequence could fold independently into its active conformation. Here we show specific cytotoxicity resulting from siRNA-induced silencing of EEF2, as well as specific delivery to PSMA-expressing prostate cancer cells. Increasing the valency of the aptamer resulted in enhanced cytotoxicity compared with the monovalent constructs. The results presented here demonstrate the usefulness of multivalent aptamer-based delivery vehicles for siRNA therapeutics.

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Chorea may occur in systemic lupus erythematosus (SLE) and primary antiphospholipid antibody syndrome (PAPS). Vascular lesions and immune-mediated excitatory mechanisms have been proposed as the underlying pathophysiology.1,2 Accordingly, immunosuppressive therapy has been employed in antiphospholipid antibody (aPL)-associated chorea. [3][4][5] We report the correlation between clinical symptoms, laboratory activity of aPL, and striatal hypermetabolism in 18 F-fluorodeoxyglucose (FDG) PET in a patient with aPL-associated hemichorea. This patient was successfully treated with low-dose methotrexate.Case report. A 41-year-old right-handed woman developed involuntary movements of the left hand in June 1999. Within 2 weeks, the symptoms progressed to uncontrollable jerks of the left arm and leg, with clumsiness of finger movements, twitching of the left face with squeezing of the eye, and speech difficulties due to clumsiness of the tongue. She was unable to continue working. Her medical history included moderate hypertension treated with losartan 50 mg per day, hysterectomy, and cigarette smoking (12 pack-years). Family history of movement disorders was negative.A cranial MRI revealed no ischemic lesion. CSF, EEG, intraand extracranial DCI, and ophthalmologic examination results were normal. Tests for lupus anticoagulant (LA) were positive, with increased activated partial thromboplastin time (aPTT) (38.7 s; normal, 21.0 to 36.0 s) and dilute Russell viper venom time ratio (dRVVT-ratio) (2.2; normal, Ͻ1.2); the anticardiolipin antibody titer (IgG) (aCL-IgG) was elevated (86.0 U/mL; normal, Ͻ18 U/mL). All other laboratory results including platelet count, complement factor 3 and 4, anti-ds-DNA antibodies, antinuclear antibodies, HIV antibodies, treponema pallidum hemagglutination assay (serum and CSF), acanthocytes, serum copper and ceruloplasmin, and thyroid function were normal. A preliminary diagnosis of aPL-associated chorea was made.Six weeks after the first manifestation of chorea, treatment was initiated with low-dose methotrexate, 20 mg orally once per week, which led to a rapid improvement. After 4 weeks of continuous medication, choreatic movements were no longer detectable and the laboratory follow-up showed an improved result for aCLIgG (55.7 U/mL) and a downward trend of LA (aPTT 34.5 s; dRVVT-ratio 1.7).Methotrexate treatment was discontinued after 9 weeks. Eight days after the last intake, the patient again noticed involuntary movements of the left hand and foot. Neurologic examination 12 days after the last methotrexate intake confirmed a mild to moderate relapse of left-sided hemichorea. Laboratory results showed increased LA (aPTT 39.5 s; dRVVT-ratio 1.9) and aCL-IgG (75.2 U/mL). An FDG PET performed to study striatal hypermetabolism revealed an increase of FDG uptake in the right caudate nucleus as compared with the left side (6.36 Ϯ 1.5%; p Ͻ 0.05) (figure).Medication was started again at 20 mg methotrexate per week. After 2 weeks, choreatic movements were no longer detectable. After 6 weeks of co...

RNA interference (RNAi) is a powerful endogenous process initiated by short double stranded RNAs, which results in sequence-specific posttranscriptional gene silencing. The ability to block the expression of any disease-causing or disease-related protein emphasizes the huge therapeutic potential of this technology. In a clinical setting, however, the use of RNAi-based therapeutics is limited by their short serum half lives and poor uptake into cells. In this review, we provide an overview of recent patents in the field of short interfering RNA (siRNA) delivery and discuss recent progress in the development of efficient siRNA delivery vehicles enhancing the pharmacokinetic properties of RNAi-based therapeutics and promoting cellular uptake.