Allopregnanolone, an endogenous neuroactive steroid, has antidepressant and anxiolytic activity but poor oral bioavailability because of substantial first-pass hepatic metabolism. To address the broader challenge of oral bioavailability across clinically validated therapeutics in neuropsychiatry, we developed a lymphatic-targeting prodrug technology platform called Glyph in which a drug of interest is conjugated to a dietary lipid molecule using specifically designed linker chemistry to shift drug absorption to the gut lymphatic system, thus bypassing hepatic metabolism. A series of allopregnanolone prodrugs with different functional linker elements was designed, synthesized, and screened in vitro for gut lymphatic transport and plasma release. Multiple prodrugs achieved therapeutically relevant plasma allopregnanolone concentrations after oral dosing in small- and large-animal models consistent with results from in vitro screening. A triglyceride-mimetic prodrug, GlyphAllo (SPT-300 or Glyph Allopregnanolone), was selected and tested in a phase 1/2a clinical trial (NCT05129865) in 189 healthy participants. Single- and multiple-ascending oral dosing showed that this prodrug could generate therapeutically relevant plasma concentrations in trial participants. GlyphAllo was generally well tolerated and resulted in delivery of allopregnanolone to the systemic circulation and exposure-dependent pharmacodynamic effects via GABA _A (γ-aminobutyric acid type A) receptor positive allosteric modulation. In a subsequent randomized, double-blind, placebo-controlled phase 2a trial using the Trier Social Stress Test (TSST), a validated clinical test for anxiety, GlyphAllo was reported to reduce the salivary cortisol stress response compared with placebo at all post-TSST time points. Collectively, these data support further investigation of GlyphAllo for treating mood and anxiety disorders.

Lymph flows from the central nervous system (CNS) via a series of lymphatic vessels (LVs) and lymph nodes that converge at the cervical lymph ducts. In addition to maintaining fluid balance, these lymphatic ducts play a key role in transporting a wide array of substances, including endogenous metabolites, signaling molecules, immune cells, and small and macromolecular drugs. This is critical for physiological homeostasis and immune function in both intracranial (e.g., brain) and extracranial regions (e.g., nasal and oral cavities). Impaired lymphatic drainage from the brain has increasingly been linked to a range of neurological and neurodegenerative disorders. Cervical lymph duct cannulation enables the collection of lymph draining the head and brain, allowing the measurement of the concentration and transport rate of various substances via the lymphatic system. Changes in these factors in response to different challenges (e.g., drugs, stress, trauma) and diseases (e.g., stroke, infection, Alzheimer's disease) can also be determined. Here, we describe an anesthetized, deep cervical lymph duct cannulated rat model that enables lymph collection for several hours following surgery. The method may be combined with imaging and multi-omics technologies for the measurement of a wide range of parameters of interest in the lymph. This facilitates fundamental physiological and pathophysiological research of the head and neck region, as well as pharmacokinetic/pharmacodynamic studies of drugs, particularly for the treatment of CNS diseases.

Lymph flows from the central nervous system (CNS) via a series of lymphatic vessels (LVs) and lymph nodes that converge at the cervical lymph ducts. In addition to maintaining fluid balance, these lymphatic ducts play a key role in transporting a wide array of substances, including endogenous metabolites, signaling molecules, immune cells, and small and macromolecular drugs. This is critical for physiological homeostasis and immune function in both intracranial (e.g., brain) and extracranial regions (e.g., nasal and oral cavities). Impaired lymphatic drainage from the brain has increasingly been linked to a range of neurological and neurodegenerative disorders. Cervical lymph duct cannulation enables the collection of lymph draining the head and brain, allowing the measurement of the concentration and transport rate of various substances via the lymphatic system. Changes in these factors in response to different challenges (e.g., drugs, stress, trauma) and diseases (e.g., stroke, infection, Alzheimer's disease) can also be determined. Here, we describe an anesthetized, deep cervical lymph duct cannulated rat model that enables lymph collection for several hours following surgery. The method may be combined with imaging and multi-omics technologies for the measurement of a wide range of parameters of interest in the lymph. This facilitates fundamental physiological and pathophysiological research of the head and neck region, as well as pharmacokinetic/pharmacodynamic studies of drugs, particularly for the treatment of CNS diseases.