4.19. GIST Xenograft Models

Subcutaneous tumor xenografts were established by s.c. inoculation of GIST cells (100 μL of 1 × 10⁷ cells/mL) into the flank areas of 5–8-week-old female nu/nu mice. The animal protocols were approved by the N.N. Blokhin National Medical Research Center of Oncology committee (des. 2019-1. from 15.01.2019) for Ethics of Animal Experimentation, and all the experiments were conducted in accordance with the Decision No. 81 of the Council of the Eurasian Economic Commission dated November 3, 2016 “On approval of Rules of good laboratory practice of the Eurasian Economic Union in the sphere of circulation of medicines” and Directive 2010/63/EU of the European Parliament and of the Council of 22 September 2010 on the protection of animals used for scientific purposes.

And all the experiments were conducted in accordance with the Guidelines for Animal Experiments in N.N. Blokhin National Medical Research Center of Oncology. GIST xenografts were allowed to reach an appropriate volume (~200 mm³) before the animals were randomized into the treatment groups (n = 4). Mice were orally administered either 50 μL of a vehicle (negative control), IM (50 mg/kg), BGJ398 (20 mg/kg), or a combination of the drugs indicated above. The changes in tumor volume, weight, and general health were recorded every second day. After the experiments reached to its end-point, the animals were sacrificed, tumors were excised and subjected to a histopathologic examination by 2 independent pathologists, S.P. and E.M. Formalin-fixed, paraffin-embedded (FFPE) tissues were sectioned at 4 μM for hematoxylin and eosin (H&E) stain and were also subjected to IHC-staining for FGF-2 expression. Histopathologic grading of the response to the treatment was also assessed by calculating the areas of necrosis, myxoid degeneration, or fibrosis, as previously described [41]. The images were captured using ScanScope XT (Aperio technologies inc., Vista, CA, USA).