The neuronal ceroid-lipofuscinoses (NCLs) are lysosomal storage diseases (LSDs) with a prevalence of approximately 1.5 to nine per million population (1.3 to 7 per 100,000 live births). The infantile onset form termed CLN1 disease is characterized by progressive intellectual and motor deterioration, seizures, loss of vision and early death. This is caused by mutations in the CLN1 gene, which codes for the lysosomal enzyme palmitoyl-protein thioesterase-1 (PPT1) resulting in a reduction or absence of enzyme activity. CLN1 disease usually presents between age 6 and 24 months of age and there are 2-3 children with this form identified each year and 24 known children with CLN1 in the US (with likely many more undiagnosed). There is no treatment available. Collaborations Pharmaceuticals, Inc. proposes to build on the work of Dr. Sandra Hofmann (UT Southwestern) and colleagues who have previously prepared human recombinant PPT1 by expression in CHO cells. This group determined uptake in PPT1-deficient lymphoblasts and showed dependence on mannose 6- phosphate receptor. This enzyme was administered intravenously (IV) at high dose (12 mg/kg) in the PPT1 knockout mice starting at birth or beginning at 8 weeks of age. Only mice treated from birth showed increased survival and delayed motor deterioration. No adverse effects were observed. Accumulation of storage material was prevented in several organs including spleen and pancreas. Brain neuropathology was ameliorated (during the perinatal period). A more recent study involved intrathecal (IT) administration of the recombinant PPT1 in artificial CSF buffer in the PPT1 knockout mice at 4 dose levels (0, 2.6, 5.3 and 10.6 mg/ml) from 6 weeks of age. Survival increased with dosage (prolonged lifespan over 7 weeks) and motor involvement was also delayed (highly significant). 5-9% enzyme activity was also maintained in mouse brain at 248 days. This suggested the IT route is worthy of further pursuit in the clinic. We have since obtained an Orphan Drug Designation with the FDA as a biological product for a ?rare pediatric disease? which offers several benefits in future. We propose to also build on the recent studies by Dr. Cooper and colleagues that have combined intracerebral and intrathecal dosing in CLN1 of a gene therapy which suggested that targeting the brain and the spinal cord was synergistic in ameliorating the disease in the mouse model. We propose producing human recombinant PPT1 in quantities for similar mice studies evaluating combined intracerebroventricular and intrathecal administration of rhPPT1 and evaluating motor function, behavior and neuropathology. In Phase II we would assess a larger animal model such as the recently developed sheep model as well as IND enabling toxicology studies (e.g. immunotoxicology) before eventual administration to humans in clinical studies. This work is comparable to other ERTs for lysosomal storage diseases that are in clinical trials. ERTs are also currently commercially available for other diseases and while not a cure, can have a dramatic effect on the quality of life and patient development. The ability to deliver human recombinant PPT1 by multiple routes may offer the best opportunity to correct neuronal symptoms. New intellectual property may be developed in this project and our goal for commercialization would leverage the FDA rare pediatric disease Priority Review Voucher which would offer a potential return on investment and incentive for licensees.
Recombinant human palmitoyl-protein thioeserase-1 (rhPPT1) can be used as an enzyme replacement therapy for PPT1- deficient Neuronal Ceroid Lipofuscinosis (Classic Infantile Batten Disease, or CLN1 disease) when delivered via several different routes to access the brain, spinal cord and periphery. The rationale for enzyme replacement therapy is that lysosomal enzymes, including PPT1, are taken up into cells via the classical mannose 6-phosphate receptor pathway and can reduce the substrate burden and delay or stabilize disease progression. Delivery of various lysosomal enzymes to the cerebrospinal fluid has shown positive results in large animal models of other neurodegenerative lysosomal storage diseases, and ERT for CLN2 disease, another form of Batten Disease, has recently been approved by FDA. We intend to synthesize and evaluate the efficacy of combined intracerebral and intrathecal rhPPT1 to ultimately develop a similar approach for CLN1 for which no treatment is available.
