| Treatment methodologies employed in the management of head and neck cancer must be carefully chosen and matched to each patient. Currently, surgical resection with adjuvant chemotherapy and radiation are the standard of care; however, these often cause disfigurement and scarring in addition to the toxic effects of chemotherapeutics. There are benefits to a locally applied controlled release matrix that is capable of completely resorbing into the body, and responding to the invasiveness of each case by increasing delivery rate as a function of microenvironment. Matrix metalloproteinase (MMP) responsive silk-elastinlike protein polymers (SELPs) show potential for development of such matrices. MMPs, a class of enzymes overexpressed in a variety of tumors including head and neck cancer, are an ideal target for the design of a tumor responsive controlled release depot. SELPs as a class of polymers have shown benefit in matrix mediated viral gene delivery to solid tumors; however, in this dissertation it is shown that despite superior safety, tumor size suppression, and survival prolongation in a murine cancer model do not readily resorb. Through recombinant DNA technology new SELP analogues based on SELP815K were designed and synthesized. MMP-responsive SELPs with insertion sites in the three structurally distinct regions termed SELP815K-RS1, SELP815K-RS2, and SELP815K-RS5 were tested for physiochemical similarity to their parent structure, SELP815K. Structural disruption was observed as evidenced by an increase in minimum gel forming concentration, soluble fraction, and swelling ratio as a function of proximity to the main structural unit, the silk blocks. High shear force was used to condition the matrices and normalized properties more closely to SELP815K. The resultant materials were assayed for degradation in the presence of MMP-2, as well as in a murine model of head and neck cancer. All MMP-responsive polymers showed increased degradation with SELP815K-RS1 and SELP815K-RS2 degrading most effectively as evidenced by soluble fraction released from hydrogels. Similarly, upon in vivo application these two polymers exhibited the most favorable properties including increased degradation, tumor suppression, and survival elongation. These results lead the way to prospective application of this technology in the human disease condition. |
