(T1130-01-06) Cyclodextrin Modulation of Lanreotide Gel Formation and Diffusional Release from an Emulated Subcutaneous Delivery Device

Purpose: Lanreotide acetate is an octapeptide that is cyclized through a disulfide bond [1]. The aggregation of lanreotide is well characterized. Above 3% w/w concentration in water, lanreotide shows reversible aggregation and formation of nanotubes with a diameter of 24 nm which is large compared to the peptide size [2]. Independent studies confirmed a complexation of βCDs - Hydroxy propyl beta cyclodextrin (HPβCD) and Sulfobutyl ether beta cyclodextrin (SBEβCD) to aromatic side chain residues of the lanreotide sequence. In this study, we want to determine the effect of βCDs as an additive to potentially mitigate the gel formation of lanreotide acetate at high concentration (7% w/w) through complexation. We aimed to evaluate the diffusional release differences in the absence and presence of two cyclodextrins in vitro via an emulator of subcutaneous administration.

Methods: An Emulator of Subcutaneous Absorption and Release (ESCAR) system (figure 1) was used to examine in vitro release rates of lanreotide [4]. The ESCAR system used the 50kDa cellulose membrane to determine the flux rate of lanreotide (MW = 1060 g/mol). The lanreotide concentration in the receiver compartment was determined by UPLC. 1) The effect of Hyaluronic acid 5% (HLA) on the lanreotide flux from the SC site was studied. 2) The effect of varying ratios of lanreotide (LAN) to cyclodextrins on the flux of lanreotide were studied. 3) The effect of cyclodextrins on the flux of lanreotide in aggregated (7% w/w) and non-aggregated (1% w/w) states with ESCAR were tested over 7 hours.

Results: As you can see in figure 2, the LAN release in 5% HLA was slower than in PBS solution. That could be the result of change in the viscosity of the medium and the electrostatic interaction between the HLA (negatively charged) and LAN (positively charged). The results from different ratios of LAN: βCDs suggested 1:5 ratio of LAN: βCDs at 7% w/w and 1:10 ratio for LAN: βCDs at 1% w/w would be the best ratios to increase the flux rate and overcome aggregation. The lower ratio for LAN: SBEβCD showed obvious precipitations due to ionic strength. The lanreotide 1% which has no aggregation did not show significant difference (p value > 0.05) in the presence and absence of SBE-βCD and HP-βCD. Although, the observed differences, although not statistically significant could be due to 1) The larger size of the LAN: βCD complex; 2) Lower concentration of free LAN; 3) and higher viscosity of the formulation to go through the membrane. The aggregation of lanreotide at 7% significantly decreased the rate of release from the injection site to the receiver chamber (Figure 3). The presence of βCDs at the given ratio can increase the release from 53 ug/hr.cm^2 to 147 ug/hr.cm^2 and 127 ug/hr.cm^2 for HPβCD and SBEβCD, respectively.

Conclusion: This study provides insight into the potential effect of cyclic peptides aggregation on the release from a subcutaneous injection site and potential flux through a membrane. Formulations composition designed to alter aggregation, whether that is reversible or irreversible, can be used to modulate release from a subcutaneous site.

References: 1. Wolin, Edward M., et al. "Lanreotide depot: an antineoplastic treatment of carcinoid or neuroendocrine tumors." Journal of Gastrointestinal Cancer 47.4 (2016): 366-374.
2. Valéry, Céline, et al. "Molecular origin of the self-assembly of lanreotide into nanotubes: a mutational approach." Biophysical Journal 94.5 (2008): 1782-1795.
3. Patent Provisional Application - KU Ref. No. 22KU028L-01: MB Ref. No. K1262.10095US01

Acknowledgements: The author would like to thank Valentino J. Stella Endowment funds and Doctoral Student Research Fund ( DSRF) for financial support, and the Ligand pharmaceutical co. to provide the HPβCD and SBECD.

Fig.1: Emulator of Subcutaneous Absorption and Release (ESCAR) system

Fig.2: Flux rate of LAN in HLA and PBS media a) 1% w/w, b) 7% w/w lanreotide formulation

Fig.3: Flux rate of LAN in the presence and absence of CDs a) 1% LAN: 10% HPBCD/SBECD, b) 7% LAN: 35% HPBCD/SBECD