Method for controllably releasing a drug conjugate within subcutaneous tissue in response to the local concentration of an indicator

A method for controllably releasing a conjugate within subcutaneous tissue in response to the local concentration of an indicator comprising subcutaneously administering, to a patient in need thereof, a material that comprises:

• a plurality of conjugates that each include a drug covalently linked to a polymer that is a polysaccharide that includes repeating chains of 1,4-linked alpha-D-glucose residues or the polymer is covalently linked to said drug via a spacer that includes a plurality of 1,4-linked alpha-D-glucose residues, wherein said conjugates are susceptible to digestion by an enzyme present in the extracellular space of subcutaneous tissue;
• and
• a plurality of multivalent cross-linking agents each containing two or more cross-link receptors, wherein said conjugates are cross-linked by said multivalent cross-linking agents through interactions between the indicator analogs and the cross-link receptors, wherein said interactions are competitively disrupted if an amount of the indicator is present, and wherein competitive disruption of the interactions between the indicator analogs and the cross-link receptors causes the material to release the conjugate in a manner that is dependent on the local concentration of the indicator.