Bijzonder interessante presentatie die zal gegeven worden op het CF congres, volgende week in Phoenix, AZ
Ik kijk nu al met veel ongeduld uit naar de fase 2 studie met GLPG 1837 die binnenkort zal starten. Deze studie zegt veel over het potentieel van GLPG 1837 in vergelijking met Kalydeco.
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NOVEL POTENTIATORS AUGMENT EFFICACY OF TRANSLATIONAL READTHROUGH IN CFTR NONSENSE MUTATIONS
Mutyam, V.1; Xue, X.1; Bedwell, D.M.1; Baasov, T.2; Andrews, M.3; van der Plas, S.3; Conrath, K.3; Rowe, S.M.1 1. Univ. of Alabama at Birmingham, Birmingham, AL, USA; 2. Technion-Israel Institute of Technology, Haifa, Israel; 3. Galapagos NV, Generaal De Wittelaan L11A3, 2800 Mechelen, Belgium
Premature termination codons (PTCs) in CFTR result in nonfunctional CFTR protein and are the proximate cause of ~11% of CF causing alleles. Previous studies have shown that the readthrough (RT) of PTCs and CFTR protein expression and function was restored by use of aminoglycosides (AGs; gentamicin, G418) and synthetic AGs (NB124). The CFTR potentiator ivacaftor (VX-770) was successfully used in restoring CFTR function in G551D and other related mutations. We have also shown that ivacaftor can augment CFTR function following RT by potentiating rescued CFTR channels. However, ivacaftor may have deleterious effects on CFTR stability, thus the evaluation of alternative potentiators is warranted. In this study, we tested if novel CFTR potentiators alone and in combination with translational RT could improve CFTR activity in comparison to ivacaftor.
Stably transduced Fischer Rat Thyroid (FRT) G542X or R1162X epithelial cells when fully confluent, were pretreated with G418, NB124 (250?µg/mL) and transepithelial conductance (Gt) was recorded before and after CFTR stimulation by addition of forskolin (FSK, 100 nM or 10?µM) followed by investigational potentiators (GP-1, GP-2, GP-4; 10?µM) and VX-770 (10?µM). Similar studies were also carried out in primary HBE (human bronchial epithelial, F508del/G542X) cells for short circuit current (Isc) analysis. Furthermore, potentiators were also tested on FRT CFTR missense mutations with amino acid (AA) substitutions at the 542 position (Arg, Trp, Cys) that were created to study the functional consequences of AAs inserted during PTC suppression.
GP-2 (0.67?±?0.07 Gt) and VX-770 (0.42?±?0.05) showed CFTR potentiator activity in wild-type (WT) CFTR, with GP-2 exceeding the effect of VX-770 by 63%. Different doses of FSK pre-stimulation (100 nM, 10?µM) did not significantly affect potentiator activity. In FRT G542X cells, ivacaftor (0.1?± 0.003), GP-2 (0.15?±?0.003), and GP-4 (0.1?± 0.005) augmented CFTR function compared to vehicle control (P<0.05), but only when RT was induced by NB124 or G418 pretreatment (P<0.01). In both FRT G542X and R1162X, GP-2 CFTR activity was significantly greater than VX-770 (P<0.05). Potentiators with or without RT agents had no effect on FRT cells without CFTR, confirming specificity. In FRT G542 AA mutants, GP-2 was active and directly proportional to the degree of CFTR function with FSK stimulation alone and also more efficacious compared to VX-770. In primary HBE G542X cells, GP-2 induced Isc (3.7?± 0.6?µA/cm2) was significantly greater in NB124 pre-treated cells compared to VX-770 (2.3?± 0.5?µA/cm2; P<0.05); total stimulated current (GP-2?+?FSK) approached 22.8% of WT CFTR.
In conclusion these results indicate that the novel potentiator GP-2 is highly efficacious towards enhancing CFTR function following translational RT of PTCs and is superior to ivacaftor in this regard, even during chronic administration. Combination therapy (potentiators?+?RT agent) may be a useful approach to augment nonsense mutation CFTR function rescued by translational RT.