Targeted Peptide-Light Therapy Shows Potent Anti-Tumor Effects

Current cancer treatments like chemotherapy often lack specificity, leading to severe side effects and limited efficacy against aggressive tumors. Solid tumors frequently overexpress certain proteins, making them attractive targets for precision therapies. This study addresses the critical need for highly selective and effective cancer treatments that minimize harm to healthy tissues by developing a novel targeted photoimmunotherapy approach.

The IR700-conjugated bicyclic peptide demonstrated high specificity, binding MT1-MMP with a dissociation constant (Kd) of 5.2 nM. In vitro, MT1-MMP-positive cancer cells treated with the conjugate and light showed a remarkable 92% reduction in cell viability compared to untreated cells (p<0.001), while MT1-MMP-negative cells were largely unaffected, showing only a 7% viability reduction. In vivo, the photoimmunotherapy significantly suppressed tumor growth, resulting in a 78% reduction in tumor volume by day 21 compared to control groups receiving either the peptide alone or light alone (p<0.0001). Furthermore, treated mice exhibited a 2.8-fold increase in median survival time (from 25 days in controls to 70 days in the treatment group) and showed no significant systemic toxicity, with body weight remaining stable. Biodistribution studies confirmed 5-fold higher accumulation of the conjugate in tumor tissue compared to healthy organs.