Importance

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Abstract

The present invention is directed to certain block copolymers of alkylethers linked to biologically active agents. More specifically, the invention relates to a conjugate between a biologically active agent and a block copolymer comprising: a biologically active agent covalently linked to a polymer comprising an A-type linear polymeric segment of relatively hydrophilic character, the repeating units of which contribute an average Hansch-Leo fragmental constant of about -0.4 or less and have molecular weight contributions between about 30 and about 500 and a B-type linear polymeric segment of relatively hydrophobic character, the repeating units of which contribute an average Hansch-Leo fragmental constant of about -0.4 or more and have molecular weight contributions between about 30 and about 500, wherein at least about 80% of the linkages joining the repeating units for each said polymeric segment comprise an ether linkage. These block copolymers, when covalently linked with biologically active agents, can stabilize such agents, facilitate their entry into cells, enhance transport across histohematic barriers and, where the target cell has developed mechanisms to reduce the cell's sensitivity to the agent, substantially overcome such resistance. Despite the covalent attachment of a large substituent, such linked agents retain substantial activity.

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First Claim