A small-molecule inhibitor of Bcl-XL potentiates the activity of cytotoxic drugs in vitro and in vivo.

Shoemaker AR, Oleksijew A, Bauch J, Belli BA, Borre T, Bruncko M, Deckwirth T, Frost DJ, Jarvis K, Joseph MK, Marsh K, McClellan W, Nellans H, Ng S, Nimmer P, O'Connor JM, Oltersdorf T, Qing W, Shen W, Stavropoulos J, Tahir SK, Wang B, Warner R, Zhang H, Fesik SW, Rosenberg SH, Elmore SW
Cancer Res. 2006 66 (17): 8731-9

PMID: 16951189 · DOI:10.1158/0008-5472.CAN-06-0367

Inhibition of the prosurvival members of the Bcl-2 family of proteins represents an attractive strategy for the treatment of cancer. We have previously reported the activity of ABT-737, a potent inhibitor of Bcl-2, Bcl-X(L), and Bcl-w, which exhibits monotherapy efficacy in xenograft models of small-cell lung cancer and lymphoma and potentiates the activity of numerous cytotoxic agents. Here we describe the biological activity of A-385358, a small molecule with relative selectivity for binding to Bcl-X(L) versus Bcl-2 (K(i)'s of 0.80 and 67 nmol/L for Bcl-X(L) and Bcl-2, respectively). This compound efficiently enters cells and co-localizes with the mitochondrial membrane. Although A-385358 shows relatively modest single-agent cytotoxic activity against most tumor cell lines, it has an EC(50) of <500 nmol/L in cells dependent on Bcl-X(L) for survival. In addition, A-385358 enhances the in vitro cytotoxic activity of numerous chemotherapeutic agents (paclitaxel, etoposide, cisplatin, and doxorubicin) in several tumor cell lines. In A549 non-small-cell lung cancer cells, A-385358 potentiates the activity of paclitaxel by as much as 25-fold. Importantly, A-385358 also potentiated the activity of paclitaxel in vivo. Significant inhibition of tumor growth was observed when A-385358 was added to maximally tolerated or half maximally tolerated doses of paclitaxel in the A549 xenograft model. In tumors, the combination therapy also resulted in a significant increase in mitotic arrest followed by apoptosis relative to paclitaxel monotherapy.

MeSH Terms (18)

Aniline Compounds Animals Antineoplastic Agents bcl-X Protein Biphenyl Compounds Cell Line, Tumor Drug Synergism Humans Kinetics Lung Neoplasms Male Mice Mice, SCID Nitrophenols Paclitaxel Piperazines Sulfonamides Transplantation, Heterologous

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