Leveraging pH-sensitive Affinity and Multivalency for Enhanced Transport and Retention in Tumors

Non-technical abstract Molecules engineered to stick to a specific target have revolutionized how diseases are treated. The stickiness (affinity) of these molecules allows them to shut down harmful processes in the body and turn on helpful ones. But treating tumors, or masses of overgrown cancer cells, presents a unique challenge. The same stickiness to these targets also keeps the molecules from moving through tumors. Instead, the molecules build up on the outside of the tumor and do not reach the middle of the tumor where treatment is also needed. At the same time, treatments must avoid harming healthy tissue, which is common in cancer therapy. This project aims to use biotechnology to find the right balance between how strongly these molecules stick and how easily they move. The research team will design molecules whose stickiness can change over time and will also build larger molecules that can grab onto multiple targets at once. Together, these approaches will help the molecules move through tumors and stay there long enough to be effective. In the long term, this work will provide new guidelines for biotechnological design of cancer treatments and help create a wider range of therapies. Using modern biotechnology tools, scientists can create these kind of molecules and find one precise target even amongst one trillion others. The results will advance American and world healthcare and treatment of cancer. The project will also support education by engaging K–12 and undergraduate students as well as training college and graduate students in research skills and scientific communication. Technical abstract Biotechnology has produced many powerful agents against cancer, but limitations in their design have restricted their ability to eliminate solid tumors. Therapeutic proteins such as antibodies exhibit strong and specific binding; however, this high affinity can impede transport through tumor tissue by creating binding-site barriers and promoting receptor-mediated uptake at the tumor periphery, leaving the inner tumor regions untreated. Conversely, proteins with lower affinity can improve tissue perfusion but are rapidly cleared, resulting in poor retention and possible off-target effects that are detrimental to patients. The proposed research seeks to address these challenges by using biotechnology to tune the binding affinity (i.e., Kd) of targeting ligands to Epidermal Growth Factor Receptor (EGFR), which is frequently overexpressed in cancer. This outcome will be achieved through an integrated approach combining protein modeling, protein–polymer conjugate design, and experimental validation. Two strategies will be employed to control affinity and transport. First, protein engineering will be used to modulate interactions between affibody-based targeting ligands and EGFR, enabling improved penetration into tumor tissue while reducing receptor-mediated degradation. Second, affibodies will be conjugated to dendrimers to introduce multivalent interactions that enhance retention. These constructs will incorporate pH-responsive behavior, allowing affinity to increase within the tumor microenvironment and thereby improving localization to diseased tissue. This work will establish design principles for balancing binding affinity with transport and retention of therapeutic proteins in tumors. In the long term, these principles will provide a platform for developing targeted treatments across multiple tumor types and expanding the pipeline of anticancer therapeutics. The project will also provide educational opportunities that advance training in biotechnology, therapeutic design, and scientific communication across multiple student levels. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria. NSF Award ID: 2607719 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Andrew Goodwin | Institution: University of Colorado at Boulder, BOULDER, CO | Award Amount: $450,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2607719 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2607719.html