An Ultra-pH-Sensitive Logic Decodes Cancer Imaging and Immunotherapy

Abstract

Pages 186-213 are misnumbered as pages 219-246.Binary classification of cancer is a challenge in clinical diagnosis due to continuously varying cancer-associated signals in both time and space. To distinguish cancer from healthy tissue it's necessary to assess binary relationships between signals at the molecular scale. However, the naked eye cannot discriminate differences at that resolution. Further, contrast enhancement with responsive small molecules shows minute changes between cancer and healthy tissues. Therefore, our group previously developed an ultra-pH-sensitive (UPS) nanoparticle platform to discretely amplify differences of acidotic thresholds. Predicated on molecular cooperativity, a divergent phase transition behavior from nanoparticle to polymer enables an irreversible capture-and-integration in the tumor microenvironment for robust tumor margin visualization. Based on previous observations on applications of the UPS platform, here I employ a formal first-order logic to quantify ultra-pH-sensitivity in cancer diagnosis. Based on this framework, I demonstrate novel applications of UPS nanoparticles in lymph node metastasis imaging. I show that UPS nanoparticles accumulate in microscopic cancer foci inside of lymph nodes, enabling discrimination between metastatic and benign lymph nodes. Further, I determine contexts wherein near-neutral pKa UPS nanoparticles lose pH-reporting fidelity in vivo. Both UPS and PC7A nanoparticles (pKa 6.9) have a short circulation half-life and poor tumor biodistribution. To overcome this, I employ cybernetic control by co-formulating two UPS polymers into a single nanoparticle. Attenuation of micelle disassembly, through strengthened non-covalent interactions, stabilizes UPS nanoparticles for improved pharmacokinetics in blood circulation. I demonstrate two applications of these long-circulating, hybrid nanoparticles. First, I engineer HyUPS nanoparticles for improved lymph node delivery of UPS6.9 polymers through co-assembly with UPS5.3. Reporting dual pH-thresholds enables accumulation in metastatic lymph nodes. Second, I develop HySTING nanoparticles for improved accumulation of PC7A in tumors. HySTING retains the unique biological activity of PC7A, yet accumulates greater in tumors after intravenous injection. HySTING enables tumor growth inhibition in mouse models of cancer by synergizing with synthetic cyclic dinucleotide payloads. Overall, a formal logic reveals robust discrimination of cancer from normal tissue by UPS nanoparticles. However, this logic fails in certain contexts. Restoring high fidelity logic through engineering control enables ON-target cancer imaging and immunotherapy