Cell experiment:

Sulforhodamine B or the WST-1 cytotoxicity assay are performed to determine the effect of MI-773 on ACC cell viability. Briefly, 1 to 3×103 UM-HACC cells are plated per well, and treated with 0 to 40 μM MI-773 for 24 to 96 hours. To assess apoptosis, 2×105 cells are plated in 60 mm3 dishes, attached overnight, and treated with 0 to 20 μM MI-773 for 72 hours. Cells are lysed with a hypotonic buffer and stained with propidium iodide. Primary low passage ACC cells (UM-HACC-5) are stably transduced with lentiviral vectors expressing shRNA-p53 or scrambled sequence control shRNA-C and selected with 1.0 μg/mL puromycin[1].

Animal experiment:

Mice[1] To establish a patient-derived xenograft (PDX) model of ACC, human tumor fragments from the UM-HACC-5 patient are transplanted subcutaneously into the dorsal region of male severe combined immunodeficient (SCID) mice (CB.17.SCID). Two of six initial patient tumor fragments transplant, grow, and are retransplanted in vivo into new male or female mice for up to 12 passages. When tumors reach an average of 250 mm3, mice are randomized into groups and received either vehicle (polyethylene glycol-200 + D-α-tocopherol polyethylene glycol 1000 succinate), or treatment with 10, 50, or 100 mg/kg MI-773 daily by oral gavage. The ACCx6 and ACCx9 models are treated with vehicle or 100 mg/kg MI-773.

MI-773 is a small molecule inhibitor of MDM2 with IC50 value of 62nM [1].

MI-773 is a small molecule MDM2 antagonist. It is a spirooxindole derivative. MI-773 shows a high MDM2 affinity with IC50 value of 62nM in the FP competitive binding experiment. In the in vitro cell-based assay, MI-773 shows a similar inhibition efficacy with its enantiomer MI-77301. The GI50 values are 58nM and 33nM for MI-773 and MI-77301, respectively. Both MI-773 and MI-77301 exert considerable activity at dose of 100 mg/kg in mouse xenograft models of osteosarcoma, prostate cancer, colorectal cancer, leukemia or melanoma. Currently, an international and multicenter phase I trial of MI-773 is underway for patients with liposarcomas and other p53-wild-type tumors [1, 2].

References:
[1] Zak K, Pecak A, Rys B, Wladyka B, Domling A, Weber L, Holak TA, Dubin G. Mdm2 and MdmX inhibitors for the treatment of cancer: a patent review (2011-present). Expert Opin Ther Pat. 2013 Apr;23(4):425-48.
[2] Shoushtari AN, Van Tine BA, Schwartz GK. Novel treatment targets in sarcoma: more than just the GIST. Am Soc Clin Oncol Educ Book. 2014:e488-95.