Targeted therapeutic agents

Therapeutic and imaging agents which are comprised of a targeting entity, a therapeutic or treatment entity and a linking carrier are provided. The linking carrier imparts additional advantages to the therapeutic agents, which are not provided by conventional linking methods. Preferred agents of the present invention comprise a lipid construct, vesicle, liposome, or polymerized liposome. In some cases, the therapeutic or treatment entity is a radioisotope, chemotherapeutic agent, prodrug, toxin, or gene encoding a protein that exhibits cell toxicity. Preferably, the agent is further comprised of a stabilizing entity that imparts additional advantages to the therapeutic or imaging agent.