Positive-unlabeled learning identifies vaccine candidate antigens in the malaria parasite Plasmodium falciparum.

Malaria vaccine development is hampered by extensive antigenic variation and complex life stages of Plasmodium species. Vaccine development has focused on a small number of antigens, many of which were identified without utilizing systematic genome-level approaches. In this study, we implement a machine learning-based reverse vaccinology approach to predict potential new malaria vaccine candidate antigens. We assemble and analyze P. falciparum proteomic, structural, functional, immunological, genomic, and transcriptomic data, and use positive-unlabeled learning to predict potential antigens based on the properties of known antigens and remaining proteins. We prioritize candidate antigens based on model performance on reference antigens with different genetic diversity and quantify the protein properties that contribute most to identifying top candidates. Candidate antigens are characterized by gene essentiality, gene ontology, and gene expression in different life stages to inform future vaccine development. This approach provides a framework for identifying and prioritizing candidate vaccine antigens for a broad range of pathogens.

Engineered peptide-drug conjugate provides sustained protection of retinal ganglion cells with topical administration in rats.

Effective eye drop delivery systems for treating diseases of the posterior segment have yet to be clinically validated. Further, adherence to eye drop regimens is often problematic due to the difficulty and inconvenience of repetitive dosing. Here, we describe a strategy for topically dosing a peptide-drug conjugate to achieve effective and sustained therapeutic sunitinib concentrations to protect retinal ganglion cells (RGCs) in a rat model of optic nerve injury. We combined two promising delivery technologies, namely, a hypotonic gel-forming eye drop delivery system, and an engineered melanin binding and cell-penetrating peptide that sustains intraocular drug residence time. We found that once daily topical dosing of HR97-SunitiGel provided up to 2 weeks of neuroprotection after the last dose, effectively doubling the therapeutic window observed with SunitiGel. For chronic ocular diseases affecting the posterior segment, the convenience of an eye drop combined with intermittent dosing frequency could result in greater patient adherence, and thus, improved disease management.

Machine learning-driven multifunctional peptide engineering for sustained ocular drug delivery.

Sustained drug delivery strategies have many potential benefits for treating a range of diseases, particularly chronic diseases that require treatment for years. For many chronic ocular diseases, patient adherence to eye drop dosing regimens and the need for frequent intraocular injections are significant barriers to effective disease management. Here, we utilize peptide engineering to impart melanin binding properties to peptide-drug conjugates to act as a sustained-release depot in the eye. We develop a super learning-based methodology to engineer multifunctional peptides that efficiently enter cells, bind to melanin, and have low cytotoxicity. When the lead multifunctional peptide (HR97) is conjugated to brimonidine, an intraocular pressure lowering drug that is prescribed for three times per day topical dosing, intraocular pressure reduction is observed for up to 18 days after a single intracameral injection in rabbits. Further, the cumulative intraocular pressure lowering effect increases ~17-fold compared to free brimonidine injection. Engineered multifunctional peptide-drug conjugates are a promising approach for providing sustained therapeutic delivery in the eye and beyond.

A hypotonic gel-forming eye drop provides enhanced intraocular delivery of a kinase inhibitor with melanin-binding properties for sustained protection of retinal ganglion cells.

While eye drops are the most common ocular dosage form, eye drops for treating diseases of the posterior segment (retina, choroid, optic nerve) have yet to be developed. In glaucoma, eye drops are used extensively for delivering intraocular pressure (IOP)-lowering medications to the anterior segment. However, degeneration of retinal ganglion cells (RGCs) in the retina may progress despite significant IOP lowering, suggesting that a complementary neuroprotective therapy would improve glaucoma management. Here, we describe a hypotonic, thermosensitive gel-forming eye drop for effective delivery of sunitinib, a protein kinase inhibitor with activity against the neuroprotective targets dual leucine zipper kinase (DLK) and leucine zipper kinase (LZK), to enhance survival of RGCs after optic nerve injury. Further, binding of sunitinib to melanin in the pigmented cells in the choroid and retinal pigment epithelium (RPE) led to prolonged intraocular residence time, including therapeutically relevant concentrations in the non-pigmented retinal tissue where the RGCs reside. The combination of enhanced intraocular absorption provided by the gel-forming eye drop vehicle and the intrinsic melanin binding properties of sunitinib led to significant protection of RGCs with only once weekly eye drop dosing. For a chronic disease such as glaucoma, an effective once weekly eye drop for neuroprotection could result in greater patient adherence, and thus, greater disease management and improved patient quality of life.

Ion-Complex Microcrystal Formulation Provides Sustained Delivery of a Multimodal Kinase Inhibitor from the Subconjunctival Space for Protection of Retinal Ganglion Cells.

Glaucoma is the leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is one of the major risk factors for glaucoma onset and progression, and available pharmaceutical interventions are exclusively targeted at IOP lowering. However, degeneration of retinal ganglion cells (RGCs) may continue to progress despite extensive lowering of IOP. A complementary strategy to IOP reduction is the use of neuroprotective agents that interrupt the process of cell death by mechanisms independent of IOP. Here, we describe an ion complexation approach for formulating microcrystals containing ~50% loading of a protein kinase inhibitor, sunitinib, to enhance survival of RGCs with subconjunctival injection. A single subconjunctival injection of sunitinib-pamoate complex (SPC) microcrystals provided 20 weeks of sustained retina drug levels, leading to neuroprotection in a rat model of optic nerve injury. Furthermore, subconjunctival injection of SPC microcrystals also led to therapeutic effects in a rat model of corneal neovascularization. Importantly, therapeutically relevant retina drug concentrations were achieved with subconjunctival injection of SPC microcrystals in pigs. For a chronic disease such as glaucoma, a formulation that provides sustained therapeutic effects to complement IOP lowering therapies could provide improved disease management and promote patient quality of life.