Phase 2a, Exploratory Study to Evaluate the Safety, Efficacy, Tolerability and Pharmacokinetics of XPF-002 in Patients With Primary/Inherited Erythromelalgia

Phase 2a, Exploratory, Double-blind, Placebo-controlled Two-part Study to Evaluate the Safety, Efficacy, Tolerability and Pharmacokinetics of Topically Applied XPF-002 (XEN402 8% w/w Ointment) in Patients With Primary/Inherited Erythromelalgia

This is a Phase 2a single-center, randomized, double-blind, Placebo-controlled, parallel group study with XPF-002 applied twice daily over 14 or 21 days in patients with Primary/Inherited Erythromelalgia (IEM). The purpose of this study is to determine whether XPF-002 is safe and effective in the treatment of pain caused by IEM.

Your role in the study would include:

• Travelling to the clinic (in Anniston, Alabama, USA) for 3 out-patient visits, each lasting approximately 1 day
• Travelling and staying in the clinic for 2 in-patient stays:
• For the first in-patient visit you will have to spend 8 days and 7 nights in the clinic
• For the second in-patient visit you will have to spend 2 days and 1 night in the clinic You can bring books, laptops and DVDs to the clinic.

If you do not live within driving distance to the clinic you will need to stay in the local area (in Anniston, at a local hotel) for 1 to 2 weeks while you use the ointment, in addition to the in-patient portion of the study.

Inclusion Criteria:

• Must have a Body Mass Index (BMI) of 18-40 kg/m2 (inclusive)
• Have primary or inherited erythromelalgia (IEM)
• Experience flares of pain in your feet or hands caused by erythromelalgia
• Be generally healthy (apart from your pain)
• Stop taking your usual pain medications and certain other medications for up to 11.5 weeks
• Not be pregnant or breast-feeding
• Must be able and willing to provide informed consent and willing to comply with all study procedures and restrictions

Exclusion Criteria:

• Must not be in constant pain (must not continually be in moderate pain, 3/10 or more)
• Coexistent source of pain from other conditions that may interfere with the study interpretation
• HIV, Hepatitis B or C
• Treatment for significant depression within 6 months of Screening
• Not willing to use adequate contraception
• Alcoholism, alcohol or substance abuse
• Presence or history of major psychiatric disturbance
• Any other condition or finding that may pose undue risk for participation
• Use of any other investigational drug in the 30 days prior to dosing
• Donation or loss of whole blood or plasma prior to dosing as follows: 50 mL to 499 mL within 30 days, or more than 499 mL within 56 days
• Employee or relative of an employee who is directly involved in the study