Background:

Rigosertib (ON-01910,Estybon) is a potent, specific PLK1 inhibitor with IC50 value of 9nM. Rigosertib strongly inhibited the proliferation of cancer cell lines, with observed IC50 values in the nanomolar range for both HeLa (115 nM) and C33A (45 nM) cells. In contrast, rigosertib had a minimal effect on normal cell lines, BJ and Ect1/E6E7 (IC50 >0.1 mM) [1]

HeLa and C33A cells demonstrated a complete (>95%) G2/M arrest at concentrations of rigosertib >0.5 μM, whereas at<0.2 μM no clear perturbation of the cell cycle was evident. Normal cells were less affected by rigosertib [1].

Rigosertib has been reported to be a more potent radiosensitizer than cisplatin in vivo [1].

Reference:
[1]?Agoni?L1,?Basu?I2,?Gupta?S3,?Alfieri?A2,?Gambino?A4,?Goldberg?GL5,?Reddy?EP6,?Guha?C7.Rigosertib?is?a?more?effective?radiosensitizer?than?cisplatin?in?concurrent?
chemoradiation?treatment?of?cervical?carcinoma,?in?vitro?and?in?vivo.?Int?J?Radiat?Oncol?Biol?Phys.?2014?Apr?1;88(5):1180-7.