CBL-0137 is an inhibitor of the histone chaperone, FACT which can also activate p53 and inhibits NF-κB with EC₅₀s of 0.37 and 0.47 µM, respectively. IC50 & Target: FACT^[1]
EC50: 0.37µM (p53), 0.47 µM (NF-Κb)^[2] In Vitro: Treatment with CBL-0137 leads to complete absence of living cells at concentrations above 2.5 μM. CBL-0137 causes a greater reduction in the number of colonies formed of not only MiaPaCa-2 cells when combined with gemcitabine, but also gemcitabine-resistant PANC-1 cells. Treatment of human pancreatic cancer cells with CBL-0137 results in a dose dependent reduction of protein and mRNA levels of RRM1 and RRM2. CBL-0137 is able to prevent gemcitabine induced expression of RRM1 and RRM2 on mRNA and protein levels^[1]. In Vivo: The CBL-0137 monotherapy group and the CBL-0137-gemcitabine combination group samples show large necrotic fields, numerous apoptotic bodies and loss of tumor cells. Sub-optimal doses of 50 to 60 mg/kg CBL-0137 causes similar enhancement of gemcitabine antitumor activity as that produced by the maximum tolerated dose (MTD) of 90 mg/kg as indicated by the lack of statistically significant differences among the combination groups. CBL0137 hydrochloride inhibits FACT function through depletion of the pool of active FACT involved in transcription elongation^[1]. CBL-0137, given by oral gavage at a nontoxic dose of 30 mg/kg per day on a 5 days on/2 days off schedule, suppresses tumor growth in xenografts of colon (DLD-1), renal cell carcinoma (Caki-1), and melanoma (Mel-7) tumor cell lines and transplanted surgical samples from patients with pancreatic ductal adenocarcinoma^[2].