Abstract B038: Toward minimally invasive detection of early ovarian cancer lesions with ultrasound

Purpose: We aim to engineer STIC-binding ultrasound contrast agents by building on recent ultrasound technology and newly discovered targets for STIC lesions to develop a minimally invasive early ovarian cancer detection method in vivo. Introduction: High-grade serous ovarian carcinoma (HGSC) is a highly aggressive cancer resulting in the 5th most common cancer-related deaths in women. This is due in part to the lack of sensitive, accurate, and non-invasive diagnostics that would allow for early intervention. Recent spatial transcriptomic analyses have revealed new surface markers that are over-expressed in STIC lesions. Utilizing these findings, we aim to develop next-generation ultrasound contrast agents by optimizing antibody affinity, antibody concentration, receptor density, stability, and signal sensitivity for STIC lesion targeted microbubbles. Materials and Methods: Functionalized microbubbles were prepared by dissolving DSPC, DSPE-PEG2K-Maleimide, and DiR. The mixture was dried, rehydrated, and sonicated for 1 hour at 70°C. The headspace was exchanged with perfluorobutane gas and vigorously shaken at 50 Hz. The microbubbles were washed and then conjugated with antibodies using thiol-maleimide chemistry. Microbubbles were added to immortalized ovarian cancer OAW42 or SKOV3 cells and incubated for 30 minutes before imaging with fluorescence microscopy. For tumors, microbubbles were incubated with excised subcutaneous SKOV3 tumors at 4°C for 1 hour and then imaged with a Verasonics Ultrasound System. Results: Using SKOV3 and OAW42 cells as simplified models of Folate Receptor alpha (FOLR)+ and Laminin g1 (LamC1)+ STIC lesions, we investigated the use of affinity ligands to selectively localize 1-5 mm size ultrasound contrast microbubbles that exhibit contrast in non-linear contrast imaging mode. Ultrasound bubble binding is dependent on ligand density and affinity on each cell population. As expected, we found that FOLR-antibody microbubbles bound to FOLR-hi cells with increasing abundance with increasing amounts of FOLR-antibody, compared to FOLR-low immortalized normal human fallopian tube cells and compared to control-antibody microbubbles. Additionally, we have found that smaller microbubbles may be more optimal for affinity bound ultrasound imaging. We have also shown that our FOLR-ab microbubbles produce strong non-linear ultrasound signals when incubated with ex-vivo subcutaneous SKOV3 tumors compared to non-functionalized microbubbles. Conclusion: We have demonstrated that we can synthesize targeted microbubbles that bind to novel targets on STIC lesion cells and ex vivo tumors. We envision these contrast agents to be used in the clinical HyCoSy procedure that already utilizes ultrasound to visualize fallopian tubes. Our future work is focused on determining the imaging resolution of our next-generation microbubbles with fallopian tube-on-a-chip devices to model STIC lesion size and fluid flow during imaging. Citation Format: Susanna Elledge, Zhiyang Jin, Sofia Neaher, Sangeeta Bhatia, Diamond HeadSusanna Elledge, Zhiyang Jin, Sofia Neaher, Sangeeta Bhatia, Diamond Head. Toward minimally invasive detection of early ovarian cancer lesions with ultrasound [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr B038.