Current Medicinal Chemistry - Volume 20, Issue 38, 2013

Treatment of murine EL4 T cell lymphoma with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugates of doxorubicin (Dox) leads to complete tumor regression and to the development of therapy-dependent longlasting cancer resistance. This phenomenon occurs with two types of Dox conjugates tested, despite differences in the covalent linkage of Dox to the polymer carrier. Such a cancer resistance cannot fully express in conventional treatment with free Dox, due to substantial immunotoxicity of the treatment, which was not observed in the polymer conjugates. In this study, calreticulin (CRT) translocation and high mobility group box-1 protein (HMGB1) release was observed in EL4 cells treated with a conjugate releasing Dox by a pH-dependent manner. As a result, the treated tumor cells were engulfed by dendritic cells (DC) in vitro, and induced their expression of CD80, CD86, and MHC II maturation markers. Conjugates with Dox bound via an amide bond only increased translocation of HSPs to the membrane, which led to an elevated phagocytosis but was not sufficient to induce increase of the maturation markers on DCs in vitro. Both types of conjugates induced engulfment of the target tumor cells in vivo, that was more intense than that seen with free Dox. It means that the induction of anti-tumor immunity documented upon treatment of EL4 lymphoma with HPMA-bound Dox conjugates does not rely solely on CRT-mediated cell death, but involves multiple mechanisms.

Purpose: In pancreatic cancer median survival times range around 6, 6 to 6,9 months. Here we retrospectively analyzed the outcome of immunotherapy in the additional palliative treatment of pancreatic cancer with long antigen exposition dendritic cell therapy (LANEX-DC®) in 138 patients who were treated at our institution. Patients: Data were available of 134 patients (97.1%). The median interval between first diagnosis and start of treatment was 1.4 months. Results: Therapy was well tolerated and no serious side effects were observed. The survival rate after 6 months was 72.2 % and afters 9 month 50.4%. The median survival time according to Kaplan- Meier regression analysis was 8.9 months. Median survival was significantly higher in the group of patients who started immunotherapy within 2 months following diagnosis (p=0.029) or repeated immunotherapy (p=0.027). Interestingly, younger patients <= 60 years of age lived significantly longer as patients > 60 years of age (p = 0.022). Conclusion: We were able to demonstrate in a large retrospective analysis that additional treatment with dendritic cells (LANEX-DC®) is highly effective and extends the median survival times up to 8.9 months. Furthermore we were able to demonstrate that median survival can be increased by early beginning and repetition of LANEX-DC® treatment.

G-quadruplex based DNA aptamers for human thrombin are promising pharmaceuticals as anticoagulants. Initially discovered 15-mer DNA aptamer (15-TBA) has a minimal G-quadruplex structure which is able to inhibit thrombin. 15-TBA was modified and extended to improve aptamer activity and in vivo stability providing 31-TBA, NU172, RA-36, and some others as successful examples. In this paper an interplay between G-quadruplex (pharmacophore module) and additional modules has been studied. An original turbidimetric assay and conventional coagulation tests were applied to evaluate both inhibitory activity and type of inhibiting for aptamers constructed by exchanging the modules between 31- TBA and NU172. Additional modules strongly affect pharmacophore module inhibitory activity either enhancing or reducing it. RA-36 aptamer has two putative pharmacophore entities which also interplay being functionally non-equal. 5’- truncated RA-36 has half of the activity of RA-36, and the same as for 15-TBA. On the contrary 3’-truncated RA-36 has intermediate activity in between 15-TBA and RA-36. These results indicate fine regulation of G-quadruplex inhibitory activity by additional modules, as well as non-trivial behavior of joined pharmacophore modules.

Osteoporosis is classified as a public health problem due to its increased risk for fragility fractures. Osteoporotic fractures, in particular spine and hip fractures, are associated with a high morbidity and mortality, and generate immense financial cost. The World Health Organisation (WHO) based the diagnosis of osteoporosis on the measurement of bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA). However, BMD values of subjects with versus without osteoporotic fractures overlap. Furthermore, it was reported that the anti-fracture effects of drugs could be only partially explained by their effects on BMD. Bone strength reflects the integration of BMD and bone quality. The later can be partly determined by measurements of bone microstructure. Therefore, substantial research efforts have been undertaken to assess bone microstructure by using high-resolution imaging techniques, including high-resolution peripheral quantitative computed tomography (hr-pQCT), high-resolution multi-detector computed tomography (MDCT), and high-resolution magnetic resonance imaging (MRI). Clinical MDCT and MRI systems are broadly available and allow an adequate depiction of the bone microstructure at the clinically most important fracture sites, i.e. radius, spine and hip. Bone microstructure parameters and finite element models can be computed in high-resolution MDCT and MR images. These measurements improved the prediction of bone strength beyond the DXA-derived BMD and revealed pharmacotherapy effects, which are partly not captured by BMD. Therefore, high-resolution bone imaging using clinical MDCT and MRI may be beneficial for osteoporosis diagnostics and allow a highly sensitive monitoring of drug treatment, which plays an important role in the prevention of fragility fractures.

We summarize the alterations of classical neurotransmitters and neuropeptides and the corresponding subreceptors involved in major depression. Neuronal circuits in the brainstem, hippocampus and hypothalamus are developed, since they can be used to derive a multimodal pharmacotherapy. In this sense, serotonin hypoactivity could occur through a strong presynaptic inhibition of glutaminergic neurons via the subtype 5 of metabotropic glutaminergic receptors, and noradrenaline hypoactivity could be due to an enhanced presynaptic inhibition of GABAergic neurons via GABAB receptors. In the hippocampus, dopamine hypoactivity leads to a decreased positive effect. In clinical trials, the antidepressant effect of drugs interfering with the mentioned subreceptors, for example the triple reuptake inhibitor amitifadine, is being investigated. Moreover, the alterations of neuropeptides, such as corticotropin-releasing hormone, neuropeptide Y and galanin are pointed out. The additional antidepressant effect of analogs, agonists and antagonists of the mentioned neuropeptides should be examined.

Systemic fungal infections of humans and economically important animals are increasingly common throughout the world. These infections are severe and often hard to treat with existing safe, oral medications. Thus there has been increasing research on alternatives resulting in study of natural and synthetic inhibitors of 1,3-β-Glucan synthase (GS) and chitin synthase (CS)-enzymes important in the biosynthesis of fungal cell walls that are not utilized in human biochemistry. Some such agents have recently been introduced into parenteral clinical use. There is hope that safe agents of this type with oral activity may yet emerge. This active area of research and its historic context with alternative agents is reviewed herein.

Farnesyltransferase inhibitors (FTIs) have mainly been used in cancer therapy. However, more recently, investigations on these inhibitors revealed that FTIs can be used for the treatment of other diseases such as Progeria, P. falciparum resistant malaria, Trypnosomatid, etc. Hence the development of novel FTIs is an important task for the drug discovery program. Initially, numerous peptidomimetic FTIs were developed from the template of CAAX (CVIM was the first pharmacophore model used as a peptidomimetic). Later, many non-peptidomimetic FTIs have been discovered with the structural modification of the peptidomimetics. The structural analysis of those developed FTIs by various researchers suggested that the presence of a heterocycle or a polar group in place of the thiol group is required for interaction with the Zn2+ ion. The bulky naphthyl, quinolinyl, phenyl, phenothazine, etc in this position provide better hydrophobicity to the molecules which interact with the aromatic amino acid moieties in the hydrophobic pocket. A hydrophilic region with polar groups is necessary for the polar or hydrogen bonding interactions with the amino acids or water molecules in the active site. Many FTIs have been isolated from natural products, which possessed inhibitory activity against farnesyltransferase (FTase). Among them, pepticinnamin E (9R), fusidienol (9T), gliotoxin (9V), cylindrol A (9X), etc possessed potential FTase inhibitory activities and their structural features are comparable to those of the synthetic molecules. The clinical studies progressing on FTIs showed that tipifarnib in combination with bortezomib is used for the treatment of patients with advanced acute leukemias. Successful phase I and II studies are undergoing for tipifarnib alone or in combination with other drugs/radiation for the treatment of multiple myeloma, AML, breast cancer, mantle cell lymphoma, solid tumors, non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma, etc. Phase I pharmacokinetic (maximum tolerated dose, toxicity) and pharmacodynamic studies of AZD3409 (an orally active double prodrug) is progressing on patients with solid malignancies taking 500 mg once a day. A phase II study is undergoing on lonafarnib alone and in combination with zoledronic acid and pravastatin for the treatment of Hutchinson-Gilford Progeria syndrome (HGPS) and progeroid laminopathies. Lonafarnib therapy improved cardiovascular status of children with HGPS, by improved peripheral arterial stiffness, bone structure and audiological status in the patients. Other important FTIs such as BMS-214662, LB42908, LB42708, etc are under clinical studies for the treatment of various cancers. This review concluded that the quantitative structural analysis report with an elaborative study on the natural product compounds provides ideas for development of novel molecules for the FTase inhibitory activity. The fragment based analysis is also needed to select the substituents, which provides significant inhibitory activities and can also have good pharmacokinetic properties in the clinical studies.

The issue of chiral drug is now a major theme in the design, discovery and development of new drugs. It has been shown for many pharmaceuticals that only one enantiomer contains the desired activity, and the synthesis of such drug molecules in their optically pure form is becoming increasingly important. Mitsunobu reaction was carried out between (R)- and (S)-3,4-dihydro-2H-1,5-benzoxathiepin-3-ol and purines under microwave irradiation. A contraction into a six-membered ring takes place with concomitant inversion at the stereocentre with excellent enatiomeric excesses giving rise to the homochiral 9-(2,3-dihydro-1,4-benzoxathiin-3-ylmethyl)-9H-purines. The anti-tumour activity of all enantiomers is reported against the caspase-3-deficient MCF-7 and the wild type SKBR-3 human breast cancer cells. The most active homochiral compound displays an IC50 of 1.85 μM and induces inhibition of the translation initiation factor eIF2α. All homochiral compounds included in this study show different apoptotic effects between both enantiomers with levels up to 99%. We have analyzed caspase-mediated apoptotic pathways on enantiomers and racemates. We have found a homochiral derivative that activates the canonical intrinsic caspase-8/caspase-3 apoptotic pathway on the MCF-7 cells, and a racemic compound that induces caspase-2 activation. Moreover, we demonstrate the involvement of caspase activation during cell death induced by these compounds in SKBR-3 cells.

Essential hypertension is one of the major contributors to premature morbidity and mortality due to the incresased risk for coronary heart disease, stroke, renal disease, peripheral vascular disease and vascular dementia for both men and women. However, its basic causes remain unknown. In the present work we studied the activity of several proteolytic regulatory enzymes related to renin-angiotensin-system (RAS) (aminopeptidase A, APA; aminopeptidase N, APN; aminopeptidase B, APB; and insulin-regulated aminopeptidase, IRAP); with oxytocin regulation (oxytocinase); with the metabolism of GnRH and TRH (pyrrolidone carboxypeptidase, Pcp); and with enkephalins metabolism (enkephalindegrading activity, EDA), to elucidate their role in the mechanisms responsible of essential hypertension and to discuss the possible gender differences. Serum samples of 53 individuals with essential hypertension and 60 healthy volunteers were collected and used to assay enzyme activities, gonad hormones testosterone and estradiol, TSH and free thyroxin (fT4). Differences were observed in APA, APN, Pcp and EDA specific activities, and in serum gonad hormone levels between hypertensive and control groups. Only Pcp activity showed gender differences. Regarding the RAS, APA is reduced while APN is increased, suggesting increased levels of angiotensin II and a facilitation of the conversion of angiotensin III in angiotensin IV. Thus, the changes in several RAS-regulating specific activities and other enzyme activities involved in the neuroendocrine modulation of gonad and stress-related functions are related to essential hypertension with minor gender differences. Therefore, aminopeptidases constitute new elements for the knowledge of the causes of essential hypertension and an alternative as therapeutic targets against the illness.