Mirum Pharmaceuticals (MIRM) investor relations material

Company overview and financial outlook

• Three approved medicines for rare cholestatic and other diseases, with 2023 revenue guidance of $500–$510 million and positive cash flow.

• Continued growth expected from all three medicines into next year, supported by a robust pipeline.

• Pipeline led by Volixibat for adult cholestatic diseases and MRM-3379 for Fragile X syndrome, with first patient enrolled in phase 2.

Fragile X syndrome program

• Estimated 50,000 male Fragile X patients in the US and Europe, with a billion-dollar market opportunity based on pricing comps and patient numbers.

• Phase 2 trial for MRM-3379 recently initiated; primary endpoint is safety and tolerability, with NIH Toolbox as a secondary endpoint.

• NIH Toolbox CCC domain chosen for its sensitivity and calibration to cognitive impairment; validation ongoing and supported by FDA precedent.

• Dosing in phase 2 designed to match or exceed exposures seen in comparable studies.

PSC and PBC clinical development

• PSC trial interim analysis led to continuation without changes; 20 mg dose selected for best therapeutic window.

• Baseline pruritus scores in PSC expected to mirror those in PBC studies (over 6 on a 0–10 scale).

• Minimal effect size for statistical significance likely similar to prior PBC studies (0.7 placebo-adjusted difference).

• Secondary endpoints include fatigue and sleep, which are important for patient quality of life but not powered for statistical significance.

• Diarrhea as a side effect is typically mild, transient, and manageable; real-world discontinuation rates are low.