Targeted therapy by disabling crossroad signaling networks: the survivin paradigm.

Embedded in the concept of targeted cancer therapy is the expectation that disabling a single oncogenic pathway will eliminate the tumor cells and leave the normal tissues unscathed. Although validated by clinical responses in certain malignancies, challenges exist to generalize this approach to most tumors, as multiple genetic lesions, chromosomal instability, insensitivity of the cancer stem cell compartment, and emergence of drug resistance complicate the identification and therapeutic exploitation of a single, driving oncogenic pathway. Instead, broader therapeutic prospects may be offered by targeting crossroad signaling networks that are selectively exploited in cancer and oversee multiple aspects of tumor cell maintenance. One such pathway is centered on survivin, a cancer gene that intersects cell proliferation, cell survival, and the cellular stress response. Several clinical trials targeting survivin with a collection of approaches from immunotherapy to small-molecule antagonists are currently under way. By simultaneously disabling multiple signaling circuitries, targeting survivin may provide a novel perspective in rational cancer therapy selective for specific cancer mechanisms but broadly applicable to disparate tumors regardless of their genetic makeup.