PXT3003 is a rational design, fixed combination of low-dose (RS) baclofen, naltrexone hydrochloride and D-sorbitol. The use of PXT3003 in a multicenter, randomised, placebo controlled phase II study (CLN-PXT3003-01) was well-tolerated and safe in patients with CMT1A for the three dose-levels investigated (Attarian et al., 2014). The intermediate and high dose of PXT3003 demonstrated an improvement of disability in this patient population.~Subsequently a multicenter, randomised, placebo controlled phase III study (CLN-PXT3003-02) to assess the efficacy and safety of PXT3003 in the treatment of patients with CMT1A was initiated in December 2015. In March 2017 the first patients completed the 15-month treatment with PXT3003 and rolled over into the extension study CLN-PXT3003-03.~During Period 1 (9 months), patients that were randomised to PXT3003 dose 1 or placebo in the primary study (CLN-PXT3003-02) continued in the extension study on PXT3003 dose 1 (5 mL). Patients randomised to PXT3003 dose 2 (5 mL) in the primary study (CLN-PXT3003-02) continued in the extension study on on PXT3003 dose 2 or PXT3003 twice dose 1 (2x5 mL). During Period 2, all patients continue on twice dose 1 (2X5mL).
All randomised patients with Charcot-Marie-Tooth Type 1A (CMT1A) who completed the primary study CLN-PXT3003-02, i.e. treatment with PXT3003 or placebo, are eligible to continue in the extension study CLN-PXT3003-03.~Period 1: Patients randomised to PXT3003 dose 1 or placebo in the primary study (CLN-PXT3003-02) continued in the extension study on PXT3003 dose 1 (5 mL). Patients randomised to PXT3003 dose 2 (5 mL) in the primary study (CLN-PXT3003-02) continued in the extension study on PXT3003 dose 2 or PXT3003 twice dose 1 (2x5 mL).~Period 2: All patients continue on twice dose 1 (2X5mL).