Erythropoietic Protoporphyria (EPP)

The goal of this expanded access program is to provide bitopertin to patients with EPP and XLP who have no satisfactory treatment options available in the US and to learn if bitopertin is safe to treat EPP and XLP.

PATHWAY is a Phase 2b/3 clinical study with an Open-Label Extension (OLE). It tests PORT-77 in patients with EPP, EPP2, and XLP. The study has three parts: Part 1: Phase 2b * Find the right dose of PORT-77 to lower PPIX levels in the blood * Test if PORT-77 lowers PPIX levels better than placebo * Check the safety of each dose Part 2: Phase 3 * Test if PORT-77 lowers PPIX levels better than placebo * Test if PORT-77 increases the amount of time patients spend in sunlight each day without pain compared to placebo * Check the safety of PORT-77 Part 3: Open-Label Extension (OLE) * Test the long-term effect of PORT-77 on PPIX levels and time in sun * Monitor long-term safety

The purpose of this study is to collect information about the effects of EPP/XLP in adults and adolescents. This is an observational study in which participants will not receive any treatment. Study details include: * The study duration will be up to 6 months for each participant. * After Screening, participants will have a Baseline (Day 1) visit and return for visits every 4 weeks through 24 weeks. * Assessments to evaluate EPP/XLP will include clinical laboratory tests, physical exams, vital signs measurement, blood draws for PPIX concentration, reporting of EPP/XLP-related symptoms (including completion of a daily diary), light dosimetry.