A Long-acting Injectable Delivery System of Infliximab for Chronic Colitis Treatment

Introduction: Chronic colitis, characterized by persistent inflammation of the colonic mucosa, presents a significant burden to patients due to its recurrent nature and impact on quality of life. The therapeutic landscape has evolved with the introduction of biologics like infliximab, a monoclonal antibody against tumor necrosis factor-alpha (TNF-α), which has demonstrated efficacy in reducing inflammation and maintaining remission. However, conventional treatment regimens require frequent dosing, leading to decreased patient compliance. A delivery system that can sustain therapeutic levels of biologics over an extended period can offer significant advantages. This study seeks to develop a nanoparticle-based delivery system for infliximab to achieve a controlled release profile and sustained serum concentrations for two months in a mouse model. This delivery system can potentially reduce dosing frequency, improve patient compliance, and provide consistent disease management outcomes.

Materials and

Methods: The mouse anti-TNF-α was obtained from BioXCell (Lebanon, NH, USA). Using the sequential flash nanocomplexation (FNC) and flash nanoprecipitation (FNP) process that we developed previously [1], we successfully encapsulated anti-TNF- into the polyethylene glycol-b-poly(L-lactide-co-glycolic acid) (PEG-b-PLGA) nanoparticles (NPs). The polyelectrolyte complexes (PEC) between the antibody and dextran sulfate (DS) were then co-precipitated with the block copolymer PEG-b-PLGA via hydrophobic-hydrophobic interaction [1]. The whole process used two connected multi-inlet vortex mixers (MIVM) to fabricate rapid turbulent mixing at high jet velocities (20-30 mL/min) within a vortex mixing chamber with volume of 50 μL. With an average characteristic mixing time reduced to less than 10 milliseconds, compared to the NP assembly or aggregation time of 10–100 milliseconds, this approach ensures uniform micro-mixing and consistent assembly kinetics, producing uniformly sized amphiphilic NPs. To prolong the local retention of NPs at the injection site, we encapsulated the NPs within a hyaluronic acid (HA) hydrogel. To increase the injectability, we further regulated the NP-loaded HA hydrogel into microparticles (MPs) by mechanical fragmentation into around 100 µm of diameter [2,3]. MPs could be lyophilized for long-term shelf storage.

Results, Conclusions, and Discussions: Through the refinement of the FNC/FNP processes, we obtained a nanoparticle formulation with an average size of ~300 nm (Fig, 1A), which exhibited a sustained release profile over a 100-day period at physiological temperature (37°C) in phosphate-buffered saline (PBS, Fig. 1B). We then loaded the NPs into hydrogel MPs to form the antibody LAI for further experiments. This LAI system can achieve tunable release rate and duration ranging from a few days to 80 days in mice (Fig. 1C). The steady state of antibody concentration in serum can be tuned between 20 and 100 ng/mL. By adjusting the antibody dose in different combinations of nanoparticles with different release profiles, the LAI formulation administered intramuscularly at two different levels (12.5 mg/kg or 30 mg/kg TNF-α antibody) in C57BL/6 mice showed an extended duration of serum concentration of antibody remained above the therapeutic threshold for around 3 months. The therapeutic efficacy of this optimized LAI treatment protocol is currently under evaluation using a chronic colitis model.
In conclusion, an injectable sustained release system for TNF-α antibody is engineered to maintain serum concentrations in mice. This system can significantly reduce the frequency of injections and potentially lower treatment cost and enhance patient compliance.

Acknowledgements (Optional): References
[1] Hanwright PJ, et al. Biomaterials. 2022 Jan; 280: 121244.
[2] Yao ZC, et al. Small. 2022 Sep; 18(36): e2202309.
[3] Li L, et al. Sci Adv. 2023 Jan; 9(1): eade1067.