Technology evaluation: ISIS-3521.

It is well known that the PKC family of enzymes is involved in the propagation of intracellular signals and is implicated in cancers, inflammatory processes, cardiovascular and endocrinological diseases. Relatively low isozyme specificity has largely limited the clinical use of PKC antagonists. The members of the PKC family differ from each other at the mRNA level and the selectivity of antisense compounds is distinguished by this feature. According to ISIS Pharmaceuticals Inc antisense compounds are highly selective inhibitors even within a family of closely-related genes [321211]. The use of these compounds could be invaluable as tools to discover the mechanisms and roles of specific PKC isozyme in normal and diseased tissues and could provide the information for better cancer treatments [226799]. The isozyme of PKC-alpha is believed to play an important role in the proliferation of several types of cancer cells [234471-323703]. Recently, ISIS Pharmaceuticals received a patent US-05885970, covering the antisense technique targeting human PKC-alpha for cancer therapy (US-0588970). In the past few years, several effective antisense oligonucleotides (AS ONs) targeting murine and human PKC-alpha isozymes have been developed and a series of positive results have been obtained in cell culture and in nude mice cancer transplantation [327453]. Phase I clinical trials have shown that relatively high doses were well tolerated with no obvious side-effects [226799]. Whether these AS ONs are beneficial to patients suffering from cancer, either alone or in combination with other chemotherapy drugs is still under evaluation in a clinical setting.