Activity of OSI-027 against Jeko xenografts in vivo. (A,C) Whole cell lysates prepared49 from separate xenografts of untreated mice (lanes 1-3) or xenografts harvested 4 hours after treatment with OSI-027 on day 3 (lanes 4,5), day 5 (lanes 6-8) or day 6 (lanes 9,10) were subjected to SDS-PAGE and probed with antibodies to the indicated antigen. (B) qRT-PCR for Bim and Puma mRNA in xenografts harvested before treatment (Pre) or on days 3, 5 and 6 at 4 hours after OSI-027. Each symbol represents the mean of 3 values from 1 xenograft. Horizontal bars, geometric mean of samples from that day. (D) Mice bearing established xenografts were treated with 3 cycles of OSI-027 at 58 mg/kg orally on a 6 days on/2 days off schedule. Results shown are the geometric mean of 5 masses from control mice and 6 masses in 5 treated mice, with each value normalized to its pretreatment value. The mass that became undetectable was arbitrarily assigned a value of 10% of its pretreatment value. (E) Appearance of Jeko xenografts in diluent- and OSI-027–treated mice on day 12 when control animals needed to be killed because masses had reached institutional limits for size. (F) Relative volumes of each Jeko xenograft on day 12 when control animals were killed and on day 23 at the end of treatment. (G) Relative volumes of Jeko xenografts on day 13 (when control animals needed to be killed, closed circles) and day 23 (end of treatment, open circles) in a separate xenograft experiment in which animals were randomized to diluent, OSI-027 50 mg/kg or rapamycin 2 mg/kg on days 1-6, 9-14, and 17-22. Horizontal bars, geometric mean of 6 (OSI-027) or 5 (other groups) mice in treatment group. (H) Proposed mechanism of cytotoxicity of OSI-027 in lymphoid cells. Steps inhibited by rapamycin, OSI-027 and Bcl-2 are shown. Dashed lines indicate that up-regulation of Bim is more variable than Puma among different lymphoid cell lines.
