Event

PhD Dissertation Defense: Rebecca Johnson

Friday, September 18, 2026
9:30 a.m.
AJC 5104 (5th floor conference room)
Debbie Chu
301 405 8268
dgchu@umd.edu

Title: Improving safety and efficacy of photomedicine for treatment of gliomas

Committee members:
Dr. Huang Chiao Huang, Chair
Dr. Anthony Kim
Dr. Jenna Mueller
Dr. Giuliano Scarcelli
Dr. Srinivasa Raghavan, Dean’s Representative

Abstract:
Glioblastoma (GBM) is the most common and aggressive primary brain tumor, resulting in a median survival of only 15 months and a five-year survival rate of <5%. Characterized by its invasiveness, GBM cells can infiltrate centimeters away from the tumor, so despite surgical resection, there is always cancer left behind that causes recurrence. Once the tumor recurs, patients have limited treatment options and are only expected to live another ~6 months. This highlights two major failure points of the current GBM treatment plans. 80% of recurrent tumors are within 1-2 cm of the original resection border, so a treatment is needed to clean up the residual disease after surgery. Second, the treatment options for when the tumor does recur need to be improved. Photomedicine approaches can solve both problems. Photodynamic therapy (PDT) is a dually selective treatment that relies on the localization of a photosensitizer and laser light activation to generate cytotoxic reactive oxygen species. PDT has the potential to follow surgery and eliminate the infiltrative cancer cells around the cavity. Laser interstitial thermal therapy (LITT) is currently used to treat recurrent gliomas by directly applying high-powered laser light to the tissue to generate heat and cause cell death. However, it is limited by off-target heating causing a ~30% complication rate. This work explores LITT in combination with a novel targeted gold nanorod (GNR) formulation to localize the heating and improve patient outcomes.

The overall goal of this dissertation is to improve the clinical applicability of photomedicine and treatment options for glioma patients through novel sensitizers and improved light-delivery methods. This is achieved by 1) engineering targeted GNRs and characterizing the thermal contouring and generation in tissue-mimicking phantoms, Monte Carlo simulations, and mouse brain tissue, and 2) establishing PDT to treat residual disease in the resection cavity of client-owned canines with spontaneous gliomas using light-scattering balloons and sterile photosensitizer.