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Effect of JAK2 inhibitors in a transgenic mouse model of MPD
| Third-party funded project |
| Project title |
Effect of JAK2 inhibitors in a transgenic mouse model of MPD |
| Principal Investigator(s) |
Skoda, Radek C.
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| Organisation / Research unit |
Departement Biomedizin / Experimental Hematology (Skoda) |
| Project start |
01.04.2010 |
| Probable end |
30.09.2010 |
| Status |
Completed |
| Abstract |
In this study we used a pre-clinical mouse model of MPD that allows us to assess the effect of JAK2 inhibitors on blood parameters as well as on the proportion of mutant, JAK-V617F positive cells versus wild-type cells in peripheral blood, bone marrow and spleen. Prior to the study, lethally irradiated mouse recipients were transplanted with a 1:1 mixture of bone marrow cells from transgenic MxCre;FF1 mice that express JAK2-V617F and display a PV-like phenotype and from a mouse strain that expresses GFP in all hematopoietic lineages (UBC-GFP). This approach allows us to distinguish mutant (GFP negative) and wild-type (GFP positive) cells by flow cytometry and thus quantify the contribution of the JAK2-V617F cells to different lineages. Within 5 weeks, the transplanted mice developed a PV-like phenotype with elevated hemoglobin and at the same time we observed a disappearance of GFP positive cells in peripheral blood, indicating that the JAK-V617F positive cells rapidly outcompeted the wild-type cells (more than 90% of erythrocytes in the circulation were of MxCre;FF1 origin 5 weeks post-Tx). We used this experimental setup to examine the effects of 3 different JAK2 inhibitors: NVP-BVB808 (50 mg/kg bid and 75 mg/kg bid), TG101348 (120 mg/kg bid, the mice were given a drug holiday on day 14 of the study and the dose was subsequently lowered to 85 mg/kg bid) and NVP-BZI478 (135 mg/kg bid). Transplanted mice (8 mice per group) received inhibitor or vehicle twice daily for 21 days. The researcher responsible for the experiment and evaluation of the results did not know the real names of the compounds. The complete blood counts (CBC) were determined prior to the start of the treatment and after the termination of the study. Moreover, blood samples were collected every week to analyze the percentage of GFP positive versus negative cells in the peripheral blood. After 21 days, the mice were euthanized and the blood/ tissue samples were collected for final analysis. In the experimental groups treated with NVP-BVB808, NVP-BZI478 and TG101348 we observed a reduction in hemoglobin and other red blood cell parameters, whereas the values in vehicle group remained elevated above the physiological range. Flow cytometry of Ter119 positive peripheral blood cells showed that mice treated with the tested compounds displayed only minor, non-significant reduction in the percentage of JAK2-V617F positive (GFP negative) erythrocytes compared to the vehicle-treated group. The neutrophils normalized in the groups treated with NVP-BVB808 and NVP-BZI478. In contrast, the cohort treated with TG101348 showed the elevated neutrophil counts similar to the vehicle treated group. The most significant reduction (9.1%) was observed in the cohort treated with the NVP-BVB808 (75 mg/kg bid). The treatment with the compounds reduced the elevated lymphocyte counts (NVP-BVB808, NVP-BZI478 and TG101348) and monocyte counts (NVP-BVB808). The platelet counts remained within the normal range in vehicle-treated mice as well as in mice treated with NVP-BVB808, NVP-BZI478 and TG101348. The JAK2-V617F positive (GFP negative) fraction of CD61 positive cells showed the similar reduction in all compound-treated groups (5.7-7.5%). In addition, spleen weights were significantly reduced after the treatment with the compounds compared to vehicle group.
In summary, these data show the ability of the tested compounds to reduce the red blood cell parameters, lymphocyte counts and spleen size/weight. NVP-BVB808 and NVP-BZI478 normalized the neutrophil and monocyte counts in treated mice after 21 days. The tested compounds also demonstrated a minor degree of selectivity for the JAK2-V617F positive cells. |
| Financed by |
Private Sector / Industry
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10/05/2024
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