ORCID Profile
0000-0001-7614-0403
Current Organisation
University of Oxford
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Publisher: Cold Spring Harbor Laboratory
Date: 13-11-2020
DOI: 10.1101/2020.11.12.379701
Abstract: N-acetyl-DL-leucine is an analogue of the alpha amino acid leucine with a chiral stereocenter. The active L-enantiomer of the racemate is currently under development for rare neurological disorders. Here we present evidence that a selective recognition of N-acetyl-L-leucine versus L-leucine by different uptake transporters significantly contributes to the therapeutic effects of N-acetyl-L-leucine. A previous study of the pharmacokinetics of racemic N-acetyl-DL-leucine and N-acetyl-L-leucine revealed D-L enantiomer competition and saturation kinetics, best explained by carrier-mediated uptake. The strategy we used was to first analyze the physicochemical properties associated with good oral bioavailable drugs and how these are alerted by N-acetylation by comparing N-acetyl-L-leucine with L-leucine. Using in silico computational chemistry we found that N-acetylation has a profound impact on certain physicochemical properties that can rationalize why N-acetyl-L-leucine is drug-like compared to L-leucine. Our calculations show that at physiological pH, L-leucine is a zwitterion, whereas N-acetyl-L-leucine is present as mainly an anion. Specifically, N-acetylation removes a charge from the nitrogen at physiological pH and N-acetyl-L-leucine is an anion that is then a substrate for the organic anion transporters. We examined N-acetyl-L-leucine uptake in human embryonic kidney cells overexpression candidate organic anion transporters (OAT) and pharmacological inhibitors. We found that N-acetyl-L-leucine is a translocated substrate for OAT1 and OAT3 with low affinity (Km ~10 mM). In contrast, L-leucine is known to be transported by the L-type Amino Acid Transporter (LAT) with high affinity (Km ~0.2 mM) and low capacity. The clinical consequence is that L-leucine uptake becomes saturated at 50-fold lower concentration than N-acetyl-L-leucine. These results demonstrate a mechanism of action that explains why N-acetyl-L-leucine is effective as a drug and L-leucine itself is not.
Publisher: Cold Spring Harbor Laboratory
Date: 16-03-2020
DOI: 10.1101/2020.03.11.20034256
Abstract: The lack of approved treatments for the majority of rare diseases is reflective of the unique challenges of orphan drug development. Novel methodologies, including new functionally relevant endpoints, are needed to render the development process more feasible and appropriate for these rare populations, and thereby expedite the approval of promising treatments to address patients’ high unmet medical need. Here, we describe the development of an innovative master protocol and primary outcome assessment to investigate the modified amino acid N-acetyl-L-leucine (Sponsor Code: IB1001) in three seperate, multinational, phase II trials for three ultra-rare, autosomal-recessive, neurodegenerative disorders: Niemann-Pick disease type C (NPC), GM2 Gangliosidoses (Tay-Sachs and Sandhoff disease “GM2”), and Ataxia Telangiectasia (A-T). The innovative IB1001 master protocol and novel CI-CS primary endpoints were developed through a close collaboration between the Industry Sponsor, Key Opinion Leaders, representatives of the Patient Communities, and National Regulatory Authorities. As a result, the open-label, rater-blinded study design is considerate of the practical limitations of recruitment and retention of subjects in these ultra-orphan populations. The novel primary endpoint, the Clinical Impression of Change in Severity © (CI-CS), accommodates the heterogenous clinical presentation of NPC, GM2, and A-T: at screening, the Principal Investigator appoints for each patient a primary anchor test (either the 8 Meter Walk Test (8MWT) or 9 Hole Peg Test of the Dominant Hand (9HPT-D)) based on his/her unique clinical symptoms. The anchor tests are videoed in a standardized manner at each visit to capture all aspects related to the patient’s functional performance. The CI-CS assessment is ultimately performed by independent, blinded raters who compare videos of the primary anchor test from three periods: baseline, the end of treatment, and the end of a post-treatment washout. Blinded to the timepoint of each video, the raters make an objective comparison scored on a 7-point Likert scale of the change in the severity of the patient’s neurological signs and symptoms from Video A to Video B. To investigate both the symptomatic and disease-modifying effects of treatment, N-acetyl-L-leucine is assessed during two treatment sequences: a 6-week parent study, and one-year extension phase. The novel CI-CS assessment, developed through a collaboration of all stakeholders, is advantageous in that it better ensures the primary endpoint is functionally relevant for each patient, is able to capture small but meaningful clinical changes critical to the patients’ quality of life (fine-motor skills gait), and blinds the primary outcome assessment. The results of these three trials will inform whether N-acetyl-L-leucine is an effective treatment for NPC, GM2, and A-T, and can also serve as a new therapeutic paradigm for the development of future treatments for other orphan diseases. The three trials (IB1001-201 for Niemann-Pick disease type C (NPC) IB1001-202 for GM2 Gangliosidoses (Tay-Sachs and Sandhoff) IB1001-203 for Ataxia-Telangiectasia (A-T)) have been registered at www.clinicaltrials.gov ( NCT03759639 NCT03759665 NCT03759678 ), www.clinicaltrialsregister.eu (EudraCT: 2018-004331-71 2018-004406-25 2018-004407-39) and www.germanctr.de (DR KS-ID: DRKS00016567 DRKS00017539 DRKS00020511).
Publisher: Elsevier BV
Date: 10-2004
Publisher: Cold Spring Harbor Laboratory
Date: 21-10-2022
DOI: 10.1101/2022.10.21.513169
Abstract: The human genome contains numerous duplicated regions, such as parent-pseudogene pairs, causing sequencing reads to align equally well to either gene. The extent to which this ambiguity complicates transcriptomic analyses is currently unknown. This is concerning as many parent genes have been linked to disease, including GBA1, causally linked to both Parkinson’s and Gaucher disease. We find that most of the short sequencing reads that map to GBA1 , also map to its pseudogene, GBAP1 . Using long-read RNA-sequencing in human brain, where all reads mapped uniquely, we demonstrate significant differences in expression compared to short-read data. We identify novel transcripts from both GBA1 and GBAP1 , including protein-coding transcripts that are translated in vitro and detected in proteomic data, but that lack GCase activity. By combining long-read with single-nuclear RNA-sequencing to analyse brain-relevant cell types we demonstrate that transcript expression varies by brain region with cell-type-selectivity. Taken together, these results suggest a non-lysosomal function for both GBA1 and GBAP1 in brain. Finally, we demonstrate that inaccuracies in annotation are widespread among parent genes, with implications for many human diseases.
Publisher: Elsevier BV
Date: 10-2007
DOI: 10.1016/J.IMMUNI.2007.08.017
Abstract: Invariant natural killer T (iNKT) cells are a subset of innate lymphocytes that recognize lipid antigens in the context of CD1d and mediate potent immune regulatory functions via the rapid production of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). We investigated whether erse Toll-like receptor (TLR) signals in myeloid dendritic cells (DCs) could differentially stimulate iNKT cells. Together with the lipopolysaccharide-detecting receptor TLR4, activation of the nucleic acid sensors TLR7 and TLR9 in DCs were particularly potent in stimulating iNKT cells to produce IFN-gamma, but not IL-4. iNKT cell activation in response to TLR9 stimulation required combined synthesis of type I interferon and de novo production of charged beta-linked glycosphingolipid(s) by DCs. In addition, DCs stimulated via TLR9 activated both iNKT cells and NK cells in vivo and protected mice against B16F10-induced melanoma metastases. These data underline the role of TLR9 in iNKT cell activation and might have relevance to infectious diseases and cancer.
Publisher: Public Library of Science (PLoS)
Date: 03-2019
Publisher: Public Library of Science (PLoS)
Date: 24-09-2020
Publisher: Elsevier BV
Date: 09-2004
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
No related grants have been discovered for Frances Platt.