An Upcoming Clinical Study to Measure the Safety and Impact of a Drug Called Macitentan in Teenage and Adult Fontan Patients.

Prospective, Multi-center, Single-arm, Open-label Long-term Study Assessing the Safety, Tolerability, and Effectiveness of Macitentan in Fontan-palliated Adult and Adolescent Subjects

The aim of this open-label (OL) trial is to study the long-term use of macitentan for up to 2 years in Fontan-palliated adult and adolescent patients beyond the 52 weeks of treatment in the parent RUBATO double-blind (DB) study (AC-055H301, NCT03153137). This OL trial studies the long-term effect of macitentan in Fontan-palliated patients as it is not known if the effect of macitentan is sustained beyond 52 weeks (end of the parent RUBATO DB study). In addition, the trial also studies the long-term safety of macitentan as this is also unknown. Furthermore, the opportunity will be given to patients who were on placebo in the parent RUBATO DB study to receive macitentan 10 mg and benefit from a potentially active treatment.

Inclusion Criteria:

• Written informed consent/assent from the subject and/or a legal representative prior to initiation of any study-mandated procedures.

• Subjects who have completed Week 52 of the parent AC-055H301/RUBATO DB study (NCT03153137)

• Women of childbearing potential must:

  1. have a negative serum pregnancy test prior to first intake of OL study drug, and,
  2. agree to perform monthly pregnancy tests up to the end of the safety follow up (S-FU) period, and,
  3. use reliable methods of contraception from enrollment up to at least 30 days after study treatment discontinuation.

Exclusion Criteria:

• Clinical worsening leading to medical interventions including reoperation of Fontan circulation (Fontan take-down) during the enrollment period
• Systolic blood pressure < 90 mmHg (< 85 mmHg for subjects < 18 years old and < 150 cm of height) at rest
• Criteria related to macitentan use
• Any known factor or disease that may interfere with treatment compliance or full participation in the study