Poster X12 - Nanosilicate Hydrogel Composites for the Delivery of Monoclonal Antibodies for the Treatment of Breast Cancer

Introduction: The combination of Herceptin (chemical name: Trastuzumab), a leading monoclonal antibody (mAb) for HER2-positive breast cancer, with 2D nanosilicates (NS) and polyethylene glycol (PEG) hydrogel presents a novel approach for advanced targeted therapy for the treatment of breast cancer. This synergistic integration capitalizes on the specific binding properties of Herceptin to HER2 receptors, enhanced mechanical strength and biocompatibility of 2D nanosilicates, and the tunable and biocompatible nature of PEG hydrogel. The incorporation of 2D nanosilicates reinforces the structural stability of the PEG hydrogel and adsorbs Herceptin electrostatically, enabling sustained mAb release, thereby optimizing its therapeutic efficacy. This platform offers sustained and localized release of Herceptin, with the potential to minimize systemic toxicity and enhance drug bioavailability for improved patient outcomes. Furthermore, the combination of Herceptin with 2D nanosilicates and PEG hydrogel demonstrates significant potential for personalized and effective breast cancer therapy, highlighting a promising direction for the development of the next-generation targeted cancer treatments.

Materials and

Methods: Laponite XLG particles (disc-shaped, ~30 nm x 1 nm) abbreviated here as NS for nanosilicates were used. For NS-mAb complexation, NS powder was first dispersed in DI water and probe sonicated for 15 s in a 1 s on/ 1 s off pattern. Sizes of NS-only particles and NS-mAb complexes were measured via dynamic light scattering (DLS). NS powder was dispersed in DI water at 30 mg/mL using sonication. For NS-mAb complexes, the NS dispersion (30 mg/mL) was combined with mAb stock solution (50 mg/mL) to achieve final concentrations of 1 mg/mL for both NS and mAb, and 95% v/v DI water. The mixture was incubated at room temperature for 30 min and mixed before DLS measurements to prevent sedimentation, which was not observed within 30 min post-mixing. For mAb release studies, at specified time intervals, samples were centrifuged for 1 min and 150 µl of release buffer was collected and replaced with fresh DI water. Absorbance was measured at 280 nm with a SpectraMax i3 plate reader (Molecular Devices, San Jose, CA). NS-mAb complexes were also imaged via microscopy (Zeiss Axiovert 200).

Results, Conclusions, and Discussions: Here we used disk shaped NS, which have negatively charged faces and positively charged edges, to electrostatically adsorb Herceptin (positively charged) to the NS faces for subsequent sustained release. To observe the differences in complexation between NS and mAb, various concentrations of each were tested. Initial screenings helped determine the most promising concentrations for further studies. NS concentrations tested included 0.5, 1.0, and 1.5 mg/mL, while mAb concentrations tested were 0.5, 1.0, and 3.0 mg/mL. Figure 1 depicts a contour plot illustrating size variations across different NS and mAb concentrations. Microscopy was then utilized to depict physical variation between complex formations shown if Figure 2. These specific concentrations were chosen to optimize the interaction and stability of the NS-mAb complexes for subsequent analyses. Results are reported using NS/mAb ratio of 0.2, 0.3, 0.5, 1.0, 1.5, and 2.0.
The ratio of NS to mAb was found to impact the size and degradability/dissociation of the resulting complexes illustrated in Figure 3. It was observed that smaller NS/mAb ratios formed smaller complexes, degraded faster and released the mAb at a higher rate than larger ratios. This faster release at lower ratios can be attributed to the limited space within the NS to accommodate the abundance of mAb, leading to a breakthrough effect. More equivalent or higher NS/mAb ratios provide adequate space for mAb absorption onto the NS, reducing competition among mAb molecules. Consequently, these ratios allow for a more stable complex formation with less variation in size, facilitating a controlled and sustained release of mAb from the NS. Our current work is focused on encapsulating the NS/mAb complexes in PEG hydrogels for sustained release.
These findings highlight the importance of selecting appropriate NS and mAb concentrations to achieve controlled and sustained release in therapeutic applications, as well as the potential for additional studies using PEG hydrogels to further enhance delivery.

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