Aminothiazolones as potent, selective and cell active inhibitors of the PIM kinase family.

We have previously reported the discovery of a series of rhodanine-based inhibitors of the PIM family of serine/threonine kinases. Here we described the optimisation of those compounds to improve their physicochemical and ADME properties as well as reducing their off-targets activities against other kinases. Through molecular modeling and systematic structure activity relationship (SAR) studies, advanced molecules with high inhibitory potency, reduced off-target activity and minimal efflux were identified as new pan-PIM inhibitors. One example of an early lead, OX01401, was found to inhibit PIMs with nanomolar potency (15 nM for PIM1), inhibit proliferation of two PIM-expressing leukaemic cancer cell lines, MV4-11 and K562, and to reduce intracellular phosphorylation of a PIM substrate in a concentration dependent manner.

Thiazolidine derivatives as potent and selective inhibitors of the PIM kinase family.

The PIM family of serine/threonine kinases have become an attractive target for anti-cancer drug development, particularly for certain hematological malignancies. Here, we describe the discovery of a series of inhibitors of the PIM kinase family using a high throughput screening strategy. Through a combination of molecular modeling and optimization studies, the intrinsic potencies and molecular properties of this series of compounds was significantly improved. An excellent pan-PIM isoform inhibition profile was observed across the series, while optimized examples show good selectivity over other kinases. Two PIM-expressing leukemic cancer cell lines, MV4-11 and K562, were employed to evaluate the in vitro anti-proliferative effects of selected inhibitors. Encouraging activities were observed for many examples, with the best example (44) giving an IC50 of 0.75µM against the K562 cell line. These data provide a promising starting point for further development of this series as a new cancer therapy through PIM kinase inhibition.

Biokinetic and dosimetric studies of 188Re-hyaluronic acid: a new radiopharmaceutical for treatment of hepatocellular carcinoma.

UNLABELLED: Hepatocellular carcinoma (HCC) is the most common primary liver cancer and has very limited therapeutic options. Recently, it has been found that hyaluronic acid (HA) shows selective binding to CD44 receptors expressed in most cancer histotypes. Since the trend in cancer treatment is the use of targeted radionuclide therapy, the aim of this research was to label HA with rhenium-188 and to evaluate its potential use as a hepatocarcinoma therapeutic radiopharmaceutical. METHODS: (188)Re-HA was prepared by a direct labelling method to produce a ReO(O-COO)(2)-type coordination complex. (188)Re-HA protein binding and its stability in saline, phosphate buffer, human serum and cysteine solutions were determined. Biokinetic and dosimetric data were estimated in healthy mice (n=60) using the Medical Internal Radiation Dose methodology and mouse model beta-absorbed fractions. To evaluate liver toxicity, alanine aminotranferase (AST) and aspartate aminotranferase (ALT) levels in mice were assessed and the liver maximum tolerated dose (MTD) of (188)Re-HA was determined. RESULTS: A stable complex of (188)Re-HA was obtained with high radiochemical purity (>90%) and low serum protein binding (2%). Biokinetic studies showed a rapid blood clearance (T(1/2)alpha=21 min). Four hours after administration, (188)Re-HA was almost totally removed from the blood by the liver due to the selective uptake via HA-specific receptors (73.47+/-5.11% of the injected dose). The liver MTD in mice was approximately 40 Gy after 7.4 MBq of (188)Re-HA injection. CONCLUSIONS: (188)Re-HA complex showed good stability, pharmacokinetic and dosimetric characteristics that confirm its potential as a new agent for HCC radiation therapy.

Biodistribution imaging of a paclitaxel-hyaluronan bioconjugate.

INTRODUCTION: Gamma-ray detectors represent sensitive and noninvasive instruments to evaluate in vivo the metabolic trapping of radiopharmaceuticals. This study aimed to assess the imaging biodistribution of a [(99m)Tc]-radiolabelled new prototype bioconjugate composed of paclitaxel linked to hyaluronan (ONCOFID-P). METHODS: A small gamma camera providing high-resolution images was employed. Imaging of biodistribution following intravenous, intraperitoneal, intravesical and oral administration was carried out for a 2-h period in anesthetized mice receiving [(99m)Tc]ONCOFID-P. At the end of the observation time, radioactivity in organs was directly measured. As a control, groups of mice were treated with free [(3)H]paclitaxel given according to the same administration routes, and organ biodistribution of the drug was assessed after 2 h. RESULTS: Intravenous inoculation of [(99m)Tc]ONCOFID-P was followed by a rapid and strong liver uptake. In fact, almost 80% of the imaging signal was detected in this organ 10 min after injection and such value remained constant thereafter, thus indicating that the bioconjugate given through the intravenous route could be well suited to targeting primary or metastatic liver neoplasias. Imaging of the bladder, abdomen and gastrointestinal tract after local administration disclosed that the radiolabelled compound remained confined to the cavities, suggesting a potential regional application for transitional bladder cell carcinomas, ovarian cancers and gastric tumors, respectively. Free [(3)H]paclitaxel biodistribution profoundly differed from that of [(99m)Tc]ONCOFID-P. CONCLUSIONS: Conjugation of drugs with polymers results in new chemical entities characterized by a modified biodistribution pattern. Therefore, preclinical studies based on imaging analysis of such new compounds can suggest novel therapeutic applications.

Detection of sites of infection in mice using 99mTc-labeled PN(2)S-PEG conjugated to UBI and 99mTc-UBI: a comparative biodistribution study.

UNLABELLED: The antimicrobial peptide ubiquicidin (UBI) directly labeled with technetium-99m ((99m)Tc) has recently been shown to be specifically taken up at sites of infection; however, its chemical structure is not well defined. To address this problem, the aim of the present study was to label UBI using poly(ethyleneglycol)-N-(N-(3-diphenylphosphinopropionyl)glycyl)-S-tritylcysteine ligand (PEG-PN(2)S) in order to compare its ability to detect infection sites with that of (99m)Tc-UBI. METHODS: The PN(2)S-PEG-UBI conjugate was prepared and labeled with (99m)Tc, and its radiochemical purity was subsequently assessed. The stability of the conjugate to cysteine challenge and dilution with both saline solution and phosphate buffer was determined and serum stability and protein binding were also assessed. In vivo studies were carried out in healthy mice to study the biodistribution of (99m)Tc-PN(2)S-PEG-UBI and its precursor (99m)Tc-PN(2)S-PEG and in infected mice to compare the uptakes of (99m)Tc-UBI and (99m)Tc-PN(2)S-PEG-UBI at the site of infection using scintigraphic imaging and ex vivo tissue counting. RESULTS: (99m)Tc-PN(2)S-PEG-UBI was obtained with high radiochemical purity (98+/-1%) and high stability. The amphiphilic nature of the conjugate leads to a tendency to form micellar aggregates that explain the high protein binding values obtained. Biodistribution studies in mice showed low renal clearance followed by a predominant reticuloendothelial system clearance that limits its application in the abdominal area. Statistical analysis revealed no significant difference between (99m)Tc-UBI and (99m)Tc-PN(2)S-PEG-UBI uptake in infected mouse thigh, and the site of infection was clearly visualized using scintigraphic imaging. CONCLUSIONS: (99m)Tc-PN(2)S-PEG-UBI proved to be as effective as (99m)Tc-UBI in detecting sites of infection; however, the well-defined chemical structure of (99m)Tc-PN(2)S-PEG-UBI makes it a better candidate for clinical imaging of infection.