Compositions and methods of treating therapy resistant cancer and uses thereof

A method of delivering an active agent to a target cell in a subject, said method comprising:

• administering to the subject a composition comprising:
• at least one porous particle,
• wherein the porous particle comprises a plurality of reservoirs, and
• wherein the plurality of reservoirs comprise an open cavity that is open to a surface of the porous particle;
• at least one polymer;
• and
• at least one active agent,
• wherein the at least one active agent is covalently linked via a cleavable bond to the at least one polymer to form a polymer-active agent conjugate,
• wherein the cleavable bond is cleavable in response to an environmental condition within the target cell, and
• wherein the polymer-active agent conjugate is dispersibly contained in the plurality of reservoirs of the least one porous particle;
• wherein the polymer-active agent conjugate is released at a target cell from the porous particle;
• wherein the released polymer-active agent conjugate self-assembles into nanoparticles upon coming in contact with an aqueous environment;
• wherein the polymer-active agent conjugate enters the target cell via a vesicular transport system;
• and
• wherein the active agent is released from the polymer-active agent conjugate after cleavage of the cleavable bond.