Mouse models for pre-clinical drug testing in leukemia

TPEN/TPGS (T2) combo dramatically reduces Philadelphia chromosome-positive pro-lymphoblastic B leukemia in BALB/c mice

Acute lymphoblastic leukemia (ALL) is hematological neoplasia that affects human beings from early life to adulthood. Although ALL treatment has been effective, an important percentage of ALL patients are resilient to treatment. Therefore, there is an urgent need for testing a new combination of compounds for the treatment of this disease. Recently, combined TPEN and TPGS (T2 combo) have shown selective cytotoxic effects in vitro leukemia cells such as Jurkat, K562, and Ba/F3 cells. In this study, we aimed to test the effect of combined TPEN and TPGS agents (T2 combo) at a fixed dose (TPEN 5 mg/kg: TPGS 100 mg/kg) on leukemic Ba/F3-BCR-ABL P210 BALB-c mice model. We found that 4 successive 2-day apart intravenous injections of T2 combo showed a statistically significant reduction of Ba/F3 BCR-ABL leukemia cells (- 69%) in leukemia BALB/c mice (n = 6) compared to untreated leukemia group (n = 6). Moreover, the T2 combo was innocuous to non-leukemia BALB/c mice (n = 3) compared to untreated non-leukemia mice (control, n = 3). After treatments (day 42), all mice were left to rest until day 50. Outstandingly, the leukemia BALB/c mice treated with the T2 combo showed a lower percentage of Ba/F3-BCR-ABL P210 cells (- 84%) than untreated leukemia BALB/c mice. Furthermore, treatment of leukemia and non-leukemia mice with T2 combo showed no significant tissue alteration/damage according to the histopathological analysis of brain, heart, liver, kidney, and spleen samples; however, T2 combo significantly reduced the number of leukocytes in the bone marrow of treated leukemia mice. We conclude that the T2 combo specifically affects leukemia cells but no other tissue/organs. Therefore, we anticipate that the T2 combo might be a potential pro-oxidant combination for the treatment of leukemia patients.

Mouse models of myeloproliferative neoplasms for pre-clinical testing of novel therapeutic agents

Myeloproliferative neoplasms (MPN), are clonal hematopoietic stem cell (HSC) disorders driven by gain-of-function mutations in JAK2 (JAK2-V617F), CALR or MPL genes. MPN treatment options currently mainly consist of cytoreductive therapy with hydroxyurea and JAK2 inhibitors such as ruxolitinib and fedratinib. Pegylated interferon-alpha can induce complete molecular remission (CMR) in some MPN patients when applied at early stages of disease. The ultimate goal of modern MPN treatment is to develop novel therapies that specifically target mutant HSCs in MPN and consistently induce CMR. Basic research has identified a growing number of candidate drugs with promising effects in vitro. A first step on the way to developing these compounds into drugs approved for treatment of MPN patients often consists of examining the effects in vivo using pre-clinical mouse models of MPN. Here we review the current state of MPN mouse models and the experimental setup for their optimal use in drug testing. In addition to novel compounds, combinatorial therapeutic approaches are often considered for the treatment of MPN. Optimized and validated mouse models can provide an efficient way to rapidly assess and select the most promising combinations and thereby contribute to accelerating the development of novel therapies of MPN.

Impact of the Injection Site on Growth Characteristics, Phenotype and Sensitivity towards Cytarabine of Twenty Acute Leukaemia Patient-Derived Xenograft Models

Rodent models have contributed significantly to the understanding of haematological malignancies. One important model system in this context are patient-derived xenografts (PDX). In the current study, we examined 20 acute leukaemia PDX models for growth behaviour, infiltration in haemopoietic organs and sensitivity towards cytarabine. PDX were injected intratibially (i.t.), intrasplenicaly (i.s.) or subcutaneously (s.c.) into immune compromised mice. For 18/20 models the engraftment capacity was independent of the implantation site. Two models could exclusively be propagated in one or two specific settings. The implantation site did influence tumour growth kinetics as median overall survival differed within one model depending on the injection route. The infiltration pattern was similar in i.t. and i.s. models. In contrast to the s.c. implantation, only one model displayed circulating leukaemic cells outside of the locally growing tumour mass. Cytarabine was active in all four tested models. Nevertheless, the degree of sensitivity was specific for an individual model and implantation site. In summary, all three application routes turned out to be feasible for the propagation of PDX. Nevertheless, the distinct differences between the settings highlight the need for well characterized platforms to ensure the meaningful interpretation of data generated using those powerful tools.

Microfluidic devices for embryonic and larval zebrafish studies

Zebrafish or Danio rerio is an established model organism for studying the genetic, neuronal and behavioral bases of diseases and for toxicology and drug screening. The embryonic and larval stages of zebrafish have been used extensively in fundamental and applied research due to advantages offered such as body transparency, small size, low cost of cultivation and high genetic homology with humans. However, the manual experimental methods used for handling and investigating this organism are limited due to their low throughput, labor intensiveness and inaccuracy in delivering external stimuli to the zebrafish while quantifying various neuronal and behavioral responses. Microfluidic and lab-on-a-chip devices have emerged as ideal technologies to overcome these challenges. In this review paper, the current microfluidic approaches for investigation of behavior and neurobiology of zebrafish at embryonic and larval stages will be reviewed. Our focus will be to provide an overview of the microfluidic methods used to manipulate (deliver and orient), immobilize and expose or inject zebrafish embryos or larvae, followed by quantification of their responses in terms of neuron activities and movement. We will also provide our opinion in terms of the direction that the field of zebrafish microfluidics is heading toward in the area of biomedical engineering.

L’édition de gènes dans la découverte du médicament et l’innovation thérapeutique

On lit régulièrement dans la presse que les méthodes thérapeutiques récentes vont supplanter celles plus traditionnelles de la pharmacopée. Le biomédicament et les thérapies géniques connaissent un essor considérable, mais on s’aperçoit que chaque approche thérapeutique a ses contraintes et ses limites et que les champs thérapeutiques les plus pertinents sont le plus souvent complémentaires de ceux du médicament traditionnel, plutôt que concurrents, et bien souvent synergiques. Cette revue met en perspective les méthodes de l’édition de génomes avec celle de la découverte du médicament, dans le domaine de l’innovation thérapeutique.

Identification of mouse cathepsin K structural elements that regulate the potency of odanacatib

Cathepsin K (CatK) is the predominant mammalian bone-degrading protease and thus an ideal target for antiosteoporotic drug development. Rodent models of osteoporosis are preferred due to their close reflection of the human disease and their ease of handling, genetic manipulation and economic affordability. However, large differences in the potency of CatK inhibitors for the mouse/rat vs. the human protease orthologs have made it impossible to use rodent models. This is even more of a problem considering that the most advanced CatK inhibitors, including odanacatib (ODN) and balicatib, failed in human clinical trials due to side effects and rodent models are not available to investigate the mechanism of these failures. Here, we elucidated the structural elements of the potency differences between mouse and human CatK (hCatK) using ODN. We determined and compared the structures of inhibitor-free mouse CatK (mCatK), hCatK and ODN bound to hCatK. Two structural differences were identified and investigated by mutational analysis. Humanizing subsite 2 in mCatK led to a 5-fold improvement of ODN binding, whereas the replacement of Tyr61 in mCatK with Asp resulted in an hCatK with comparable ODN potency. Combining both sites further improved the inhibition of the mCatK variant. Similar results were obtained for balicatib. These findings will allow the generation of transgenic CatK mice that will facilitate the evaluation of CatK inhibitor adverse effects and to explore routes to avoid them.