Progranulin AAV gene therapy for frontotemporal dementia: translational studies and phase 1/2 trial interim results.

GRN mutations cause progranulin haploinsufficiency, which eventually leads to frontotemporal dementia (FTD-GRN). PR006 is an investigational gene therapy delivering the granulin gene (GRN) using an adeno-associated virus serotype 9 (AAV9) vector. In non-clinical studies, PR006 transduced neurons derived from induced pluripotent stem cells of patients with FTD-GRN, resulted in progranulin expression and improvement of lipofuscin, lysosomal and neuroinflammation pathologies in Grn-knockout mice, and was well tolerated except for minimal, asymptomatic dorsal root ganglionopathy in non-human primates. We initiated a first-in-human phase 1/2 open-label trial. Here we report results of a pre-specified interim analysis triggered with the last treated patient of the low-dose cohort (n = 6) reaching the 12-month follow-up timepoint. We also include preliminary data from the mid-dose cohort (n = 7). Primary endpoints were safety, immunogenicity and change in progranulin levels in cerebrospinal fluid (CSF) and blood. Secondary endpoints were Clinical Dementia Rating (CDR) plus National Alzheimer's Disease Coordinating Center (NACC) Frontotemporal Lobar Degeneration (FTLD) rating scale and levels of neurofilament light chain (NfL). One-time administration of PR006 into the cisterna magna was generally safe and well tolerated. All patients developed treatment-emergent anti-AAV9 antibodies in the CSF, but none developed anti-progranulin antibodies. CSF pleocytosis was the most common PR006-related adverse event. Twelve serious adverse events occurred, mostly unrelated to PR006. Deep vein thrombosis developed in three patients. There was one death (unrelated) occurring 18 months after treatment. CSF progranulin increased after PR006 treatment in all patients; blood progranulin increased in most patients but only transiently. NfL levels transiently increased after PR006 treatment, likely reflecting dorsal root ganglia toxicity. Progression rates, based on the CDR scale, were within the broad ranges reported for patients with FTD. These data provide preliminary insights into the safety and bioactivity of PR006. Longer follow-up and additional studies are needed to confirm the safety and potential efficacy of PR006. ClinicalTrials.gov identifier: NCT04408625 .

Amelioration of Neurosensory Structure and Function in Animal and Cellular Models of a Congenital Blindness.

Most genetically distinct inherited retinal degenerations are primary photoreceptor degenerations. We selected a severe early onset form of Leber congenital amaurosis (LCA), caused by mutations in the gene LCA5, in order to test the efficacy of gene augmentation therapy for a ciliopathy. The LCA5-encoded protein, Lebercilin, is essential for the trafficking of proteins and vesicles to the photoreceptor outer segment. Using the AAV serotype AAV7m8 to deliver a human LCA5 cDNA into an Lca5 null mouse model of LCA5, we show partial rescue of retinal structure and visual function. Specifically, we observed restoration of rod-and-cone-driven electroretinograms in about 25% of injected eyes, restoration of pupillary light responses in the majority of treated eyes, an ∼20-fold decrease in target luminance necessary for visually guided behavior, and improved retinal architecture following gene transfer. Using LCA5 patient-derived iPSC-RPEs, we show that delivery of the LCA5 cDNA restores lebercilin protein and rescues cilia quantity. The results presented in this study support a path forward aiming to develop safety and efficacy trials for gene augmentation therapy in human subjects with LCA5 mutations. They also provide the framework for measuring the effects of intervention in ciliopathies and other severe, early-onset blinding conditions.

Novel galanin receptor subtype specific ligands in feeding regulation.

Galanin a 29/30-residue neuropeptide has been implicated in several functions in the central nervous system, including the regulation of food consumption. Galanin and its analogues administered intraventricularly or into the hypothalamic region of brain have been shown to reliably and robustly stimulate the consumption of food in sated rodents. Three galanin receptor subtypes have been isolated, all present in the hypothalamus, but little is known about their specific role in mediating this acute feeding response. Presently, we introduce several novel GalR2 selective agonists and then compare the most selective of these novel GalR2 subtype selective agonists to known GalR1 selective agonist M617 for their ability to stimulate acute consumption of several foods shown to be stimulated by central administration of galanin. GalR1 selective agonist M617 markedly stimulated acute consumption of high-fat milk, but neither GalR2 selective agonist affected either high-fat milk or cookie mash intake. The present results are consistent with the involvement of GalR1 in mediating the acute feeding consumption by galanin and suggest an approach applicable to exploring galanin receptor specificity in normal and abnormal behavior and physiology.

Single or multiple reproductive experiences attenuate neurobehavioral stress and fear responses in the female rat.

The female brain is a dynamic structure, which expresses its plasticity most readily following reproductive experience (RE). In Experiment 1, we generated nulliparous (NP), primiparous (PP), and multiparous (MP) females (none, one, and two litters, respectively). Two weeks following the weaning of the first/second six-pup litters, the age-matched MP and PP and the non-pup-exposed NP animals were subjected to a 60-min restraint stress paradigm (enclosure in a Plexiglas restraint tube). The brains were removed and processed for c-fos immunoreactivity (c-fos-IR) in CA3 region of the hippocampus (HI) and in basolateral amygdala (BLA). MP and PP females had very similar numbers of c-fos-IR neurons in both HI and BLA, whereas both were lower than NPs. In a second experiment, the same groups were generated, together with primigravid (PG; first pregnancy) and multigravid (MG; second pregnancy) females, tested in late pregnancy. The animals were exposed to a 30-min trial in an open field and were killed, and the brains were again examined for c-fos-IR. The parous and gravid animals displayed less reactivity to the stress of the open field (i.e., reductions in behavioral measures of anxiety) and significantly less c-fos expression in both CA3 and BLA. The gravid animals displayed significantly less c-fos expression in CA3 and BLA compared to parous females, although neither group differed as a result of a second RE. The data suggest that reproductive (viz., hormonal) and/or maternal (viz., pup exposure) experience may inure a female and her brain to stress, rendering her less susceptible to the behavioral-or other-disruptions that stress sensitivity can produce. Together, these data suggest that the experiences of motherhood (pregnancy, pup exposure, suckling stimulation, etc.) summate to produce reductions in anxiety and stress responsiveness that start before and last long after pup exposure and care. Such reductions may be adaptive in the face of demands placed upon the parous vs. the NP female.