Dihydroorotate dehydrogenase inhibition acts synergistically with tyrosine kinase inhibitors to induce apoptosis of mantle cell lymphoma cells

Mantle cell lymphoma (MCL) is a non‐Hodgkin lymphoma that remains incurable with the treatment options available today. In the present study, we have identified the dihydroorotate dehydrogenase (DHODH), an essential enzyme for the de novo biosynthesis of pyrimidine‐based nucleotides, to be overexpressed in MCL in comparison to healthy peripheral blood mononuclear cells (PBMC). In vitro inhibition of the DHODH activity using a newly developed DHODH inhibitor, namely (R)‐HZ05, can induce MCL cell death in the nanomolar range independently than the P53 status of the investigated cell lines. Moreover, the combination of (R)‐HZ05 with tyrosine kinase inhibitor shows the synergistic activity on cell death. Pre‐clinical investigation on the efficacy of (R)‐HZ05 shows that it can be prolonged animal lifespan similar to ibrutinib. (R)‐HZ05 use in combination with tyrosine kinase inhibitor demonstrated a superior efficacy on tumor burden reduction and survival than either drug alone. We have demonstrated that the depletion of the pyrimidine nucleotide pool, using DHODH inhibitor, represents a new therapeutic strategy that may benefit MCL patients.

Formulation and characterisation of drug-loaded antibubbles for image-guided and ultrasound-triggered drug delivery

The aim of this study was to develop high load-capacity antibubbles that can be visualized using diagnostic ultrasound and the encapsulated drug can be released and delivered using clinically translatable ultrasound. The antibubbles were developed by optimising a silica nanoparticle stabilised double emulsion template. We produced an emulsion with a mean size diameter of 4.23 ± 1.63 µm where 38.9 ± 3.1% of the droplets contained a one or more cores. Following conversion to antibubbles, the mean size decreased to 2.96 ± 1.94 µm where 99% of antibubbles were <10 µm. The antibubbles had a peak attenuation of 4.8 dB/cm at 3.0 MHz at a concentration of 200 × 10³ particles/mL and showed distinct attenuation spikes at frequencies between 5.5 and 13.5 MHz. No increase in subharmonic response was observed for the antibubbles in contrast to SonoVue®. High-speed imaging revealed that antibubbles can release their cores at MIs of 0.6. In vivo imaging indicated that the antibubbles have a long half-life of 68.49 s vs. 40.02 s for SonoVue®. The antibubbles could be visualised using diagnostic ultrasound and could be disrupted at MIs of ≥0.6. The in vitro drug delivery results showed that antibubbles can significantly improve drug delivery (p < 0.0001) and deliver the drug within the antibubbles. In conclusion antibubbles are a viable concept for ultrasound guided drug delivery.

Proteomics in Acute Myelogenous Leukaemia (AML): Methodological Strategies and Identification of Protein Targets for Novel Antileukaemic Therapy

Enduring efforts into determination of the molecular biological status of acute myelogenous leukaemia (AML), a stem cell disease characterised by distinct blastic differentiation blocks and their extensive growth, continue to provide us with prognostically important information for more than half of all patients. In subsets of AML, molecular diagnostics rigorously guide the clinician toward the choice of optimal therapy. The in-depth characterization of leukemogenesis associated genetic alterations, such as the combined presence of activating mutations of tyrosine kinases together with altered transcription factors, and the documented impact of these mutations upon prognosis of AML, suggests AML as a primary candidate for pioneering proof-of-principle studies with new high throughput protein analysis techniques. This review aims to introduce the reader to proteomic methodology, e.g. two-dimensional polyacrylamide gel electrophoresis, mass spectrometry, SELDI and protein arrays. Examples of its use, including single cell phosphoprotein profiling in risk stratification, the probing of cellular effects of conventional chemotherapeutics and novel target determination are presented. Based on original proteomic analysis of AML, molecular characteristics of AML, in addition to knowledge of conventional therapeutics and novel drugs, we attempt to forecast the influence of proteomics in therapy development for AML.