PALO ALTO VETERANS INSTITUTE FOR RESEARCH

CLINICAL TRANSLATION OF ALLOGENEIC REGENERATIVE CELL THERAPY FOR WHITE MATTER STROKE AND VASCULAR DEMENTIA. PRINCIPAL INVESTIGATOR: IRENE LORENZO LLORENTE, PH.D.STROKE IS THE LEADING CAUSE OF ADULT DISABILITY AND THE SECOND LEADING CAUSE OF DEMENTIA. WHITE MATTER STROKE (WMS) CONSTITUTES UP TO 30% OF ALL STROKE SUBTYPES AND IS A DISTINCT PROCESS FROM "LARGE ARTERY STROKE." WMS BEGINS AS SMALL INFARCTS IN DEEP PENETRATING BLOOD VESSELS IN THE BRAIN BUT PROGRESSES, ACCUMULATES, AND EXPANDS FROM PREEXISTING LESIONS INTO ADJACENT WHITE MATTER TO PRODUCE HEMIPARESIS WITH INCOMPLETE RECOVERY, GAIT ABNORMALITIES, COGNITIVE DECLINE, AND EXECUTIVE DYSFUNCTION CHARACTERISTIC OF VASCULAR DEMENTIA (VAD). UNLIKE LARGE ARTERY STROKE, WMS DOES NOT DAMAGE NEURONAL CELL BODIES BUT PRIMARILY AFFECTS AXONAL TRACTS AND GLIAL CELLS. A CELL-BASED THERAPY CAPABLE OF REPLACING LOST GLIA AND INDUCING STRUCTURAL REPAIR IN WMS/VAD HOLDS GREAT PROMISE. WE HAVE DEVELOPED A UNIQUE ALLOGENEIC HUMAN INDUCED PLURIPOTENT STEM CELL (HIPSC)-DERIVED GLIAL ENRICHED PROGENITOR (GEP) CELL THERAPY PRODUCT FOR THE TREATMENT OF WMS AND VAD. PRECLINICAL STUDIES DEMONSTRATE THAT HIPSC-GEPS TRANSPLANTED INTO THE BRAIN AFTER WMS/VAD PROMOTE MOTOR AND COGNITIVE RECOVERY THROUGH MULTIPLE MECHANISMS OF ACTION, INCLUDING AXONAL GROWTH, ASTROCYTIC MODULATION, OLIGODENDROCYTE DIFFERENTIATION, AND REMYELINATION. THIS YEAR, WE ACHIEVED A SUCCESSFUL PRE-IND MEETING WITH THE U.S. FOOD AND DRUG ADMINISTRATION (FDA) FOR GEP-101 (HIPSC-GEPS) ON FEBRUARY 26, 2026. THE DISCUSSION, INFORMED BY THE FDA'S PRELIMINARY WRITTEN RESPONSES DATED FEBRUARY 23, 2026, FOCUSED ON FOUR PRIMARY AREAS: (1) SUITABILITY OF THE HIPSC CELL LINE AND DONOR ELIGIBILITY TESTING, (2) ADEQUACY OF THE PROPOSED CLINICAL DELIVERY DEVICE AND ADDITIONAL NONCLINICAL EVALUATION NEEDS, (3) REQUIREMENTS FOR DEVICE COMPATIBILITY TESTING TO ENSURE PRODUCT QUALITY AND DOSE ACCURACY, AND (4) QUALIFICATION OF CERTAIN MANUFACTURING RAW MATERIALS, INCLUDING THE VEEV RNA REPLICON USED DURING CELL REPROGRAMMING. OVERALL, THE FDA AGREED WITH ALL POSITIONS PRESENTED, CLARIFYING EXPECTATIONS FOR MANUFACTURING CONTROLS, DEVICE USE, AND SUPPORTING NONCLINICAL DATA PRIOR TO IND SUBMISSION.FOLLOWING THE PRE-IND MEETING, WE HAVE SUBMITTED A NEW GRANT PROPOSAL TO SECURE THE NEXT ROUND OF FUNDING AND CONTINUE ADVANCING TOWARD IND APPROVAL AND FUTURE CLINICAL TRANSLATION.

NOVEL LYMPHOCYTE CHEMOATTRACTANT RECEPTOR AND LIGAND. PRINCIPAL INVESTIGATOR: EUGENE BUTCHER, M.D.WE HAVE IDENTIFIED A NOVEL LYMPHOCYTE CHEMOATTRACTANT RECEPTOR AND ITS CHEMOATTRACTANT LIGAND, SELECTIVELY EXPRESSED IN LUNG, AIRWAYS, UPPER GI TRACT, GENITOURINARY MUCOSAE AND MUCOSA-ASSOCIATED GLANDS INCLUDING THE PANCREAS AND SALIVARY GLANDS. AIM 1: WE WILL MECHANISTICALLY PROBE THE RECEPTOR-LIGAND INTERACTIONS FOCUSING ON THE SPECIFICITY AND SIGNALING PATHWAYS ACTIVATED BY THE NOVEL RECEPTOR AND ITS ROLE AS A LYMPHOCYTE VS MYELOID CELL CHEMOTACTIC RECEPTOR. STRUCTURE-FUNCTION STUDIES WILL IDENTIFY LIGAND DOMAINS FOR RECEPTOR BINDING AND ACTIVATION. AIM 2: WILL DEFINE THE REGULATION OF THE RECEPTOR IN THE MOUSE, AND ITS ROLE IN LYMPHOCYTE POPULATION OF AND HOMING TO NON-LYMPHOID TISSUES DURING HOMEOSTASIS AND IN THE SETTING OF CHRONIC MULTI-ORGAN AUTOIMMUNE INFLAMMATION. THE ROLES OF THE PATHWAY IN IMMUNE CELL DEVELOPMENT WILL BE PROBED IN MIXED BONE MARROW CHIMERAS IN WHICH RECEPTOR-DEFICIENT VS WILD TYPE STEM CELLS COMPETE FOR RECONSTITUTION OF IMMUNE COMPARTMENTS IN LYMPHOID AND NON-LYMPHOID TISSUES. AIM 3: WILL ELUCIDATE THE TISSUE- AND CELL SUBSET-SPECIFIC EXPRESSION OF THE RECEPTOR AND LIGAND IN HUMANS.WHILE MUCH OF AIM 1 HAS BEEN COMPLETED AND PRESENTED IN OUR NATURE PUBLICATION, THIS AIM AS WELL AS THE GRANT AS A WHOLE HAS AS ITS OVERARCHING GOAL TO IDENTIFY AND CHARACTERIZE THE GPCR INTERACTIONS AND FUNCTIONS OF CXCL17. OUR ALPHA FOLD MODELING SUPPORTED OUR INITIAL CHARACTERIZATION OF CXCL17-GPR25 INTERACTION. USING THIS AS A JUMPING OFF POINT, WE ARE ASKING WHETHER IN SILICO MODELING IN SCREENING MODE CAN IDENTIFY THE FUNCTIONAL GPCR LIGANDS OF CXCL17 (AND THUS POTENTIALLY OF OTHER ORPHAN CHEMOKINES). IN HIGH THROUGHPUT SCREENING MODE, WE GENERATED AF2 MODELS OF CXCL17 INTERACTIONS WITH ALL CLASS A GPCRS AND FIND THAT THE HIGHEST SCORING MODELS INCLUDE GPR25 BUT ALSO TWO OTHER RECEPTORS: BDKRB1, THE INFLAMMATION ASSOCIATED BRADYKININ RECEPTOR, AND NTSR2, THE NEUROTENSIN RECEPTOR. OTHER RECEPTORS SHOWED NO OR UNFAVORABLE INTERACTIONS (DEFINED BY AF2 METRICS INCLUDING IPTM ON LIGAND AND RECEPTOR RESIDUES INTERACTING IN THE LIGAND BIND POCKET OF THE GPCR). THESE IN SILICO FINDINGS SUGGEST THE POSSIBILITY OF ADDITIONAL RECEPTORS FOR CXCL17 THAT COULD IMPACT VASCULAR AND NEUROBIOLOGY. A MAJOR FOCUS THIS YEAR IN REGARDS TO AIM 2 HAS BEEN ON EXPANDING AND INITIALLY CHARACTERIZING GPR25 DEFICIENT MICE, TO DEFINE THE ROLE OF GPR25 IN LYMPHOCYTE SUBSET REPRESENTATION AND DISTRIBUTION IN MUCOSAL TISSUES. WE HAVE ESTABLISHED THE COLONY AND HAVE EVALUATED BASAL LYMPHOCYTE SUBSETS IN THE RESTING STATE. THE RESULTS LARGELY PARALLEL THOSE IN CXCL17 DEFICIENT MICE, INDICATING THAT CXCL17 IS LIKELY THE ONLY OR THE PREDOMINANT CHEMOKINE LIGAND FOR GPR25. WE HAVE GENERATED MIXED (WT/KO) BONE MARROW CHIMERAS TO DEFINE THE EFFECT OF GPR25 DEFICIENCY BY EVALUATING KO LYMPHOCYTE REPRESENTATION IN COMPETITION WITH WT CELLS IN THE SAME HOST.FOR AIM 3, WE CONTINUE TO EVALUATE GPR25 EXPRESSION IN HUMAN AND MOUSE DISEASE MODELS (SCRNA SEQ DATA TO DATE FROM PUBLIC RESOURCES). WE ARE INTERESTED IN GWAS ASSOCIATIONS OF GPR25 WITH ARTERIAL STIFFNESS: WE SEE SIGNIFICANT T CELL SUBSET EXPRESSION OF GPR25 IN DATA FROM HUMAN CORONARY ARTERY DISEASE. WE ARE ALSO INTERESTED IN UNDERSTANDING THE GWAS ASSOCIATIONS OF HUMAN BLOOD GPR25 WITH AUTOIMMUNE DISEASES ESPECIALLY IBD: THROUGH COLLABORATION WITH DR. MONTGOMERY, COLOCALIZATION ANALYSIS INDICATE THAT GPR25 HAS THE HIGHEST PP4 AMONG GENES IN THE REGION FOR IBD, CROHN'S DISEASE, AND ULCERATIVE COLITIS, PRIORITIZING GPR25 AS THE LIKELY CAUSAL GENE AT THIS LOCUS. WE HAVE PERFORMED RNA SCOPE ON INTESTINAL SAMPLES FROM IBD PATIENTS (WITH OUR COLLABORATOR AND CO-INVESTIGATOR SERENA TAN) REVEALING STRONG CXCL17 EXPRESSION WITHIN SITES OF PYLORIC METAPLASIA CONSISTENT WITH SINGLE-CELL RNA-SEQ DATA AND SUPPORTING RECRUITMENT OF GPR25 IMMUNE CELLS TO INFLAMED MUCOSA. RECRUITMENT OF GPR25+ TREGS COULD EXPLAIN THE ROLE OF HIGHER PBMC GPR25 IN REDUCING IBD.