Implantation of drug delivery depots into or proximal to targeted tissue is an effective method to deliver anticancer drugs in a sustained localized manner. Herein, syringe-injectable polydextran aldehyde (PDA)-based bioadhesive gels are prepared that can locally deliver cytotoxins upon their hydrolytic fragmentation. Adhesive gels are formed by mixing doxorubicin (DOX)-functionalized PDA (DOXPDA) and bovine serum albumin (BSA) using a dual-barrel syringe. Upon mixing and delivery, the DOX-PDA reacts with the cross-linker BSA as well as the extracellular matrix via imine bond formation to define the cohesive and adhesive properties of the gel, respectively. Resulting gels are mechanically rigid (similar to 10 kPa) and adherent (adhesive stress similar to 4 kPa). Once formed, the DOX-PDA-BSA gels undergo slow hydrolytic degradation (>2 months) locally releasing free DOX and DOX-PDA as expected. Surprisingly, we found that macromolecules composed of DOX, PDA, and BSA are also released from the bulk material. These DOX-PDA-BSA macromolecules, along with free DOX and DOX-PDA conjugate, are internalized by A549 lung carcinoma cells, resulting in potent cell death.