MIRM

Research · Sep 3, 2026

[MIRM] Mirum Pharmaceuticals Thesis 2026: LIVMARLI Scales Across Rare Liver Disease and a Cholestatic Pipeline

Mirum Pharmaceuticals, Inc. (NASDAQ: MIRM) is a Foster City, California-headquartered commercial-stage rare-liver-disease biopharma focused on cholestatic and hepatic disorders — diseases where bile flow is impaired, leading to bile-acid accumulation and severe itching (pruritus), liver damage, and progression. The company was founded in 2018 by Chris Peetz (ex-Tobira Therapeutics, ex-Theravance, with long pharma-business-development background) and a team including key Lumena Pharmaceuticals/Shire-spin-off assets — specifically the IBAT-inhibitor program maralixibat (LIVMARLI) Mirum licensed from Shire (now Takeda) — IPO'd on NASDAQ 2020. Strategic focus on bile-acid biology and the IBAT (ileal bile acid transporter) mechanism: IBAT is the gut transporter recycling bile acids back to the liver — inhibiting it prevents recycling, lowering systemic bile-acid levels and reducing cholestatic itching (the dominant symptom in many cholestatic liver diseases) and potentially slowing disease progression. Commercial portfolio: LIVMARLI (maralixibat) the flagship oral once-daily IBAT inhibitor — FDA-approved September 2021 for cholestatic pruritus in Alagille syndrome (ALGS) ≥3 months (first approved drug for ALGS pruritus), expanded March 2024 to Progressive Familial Intrahepatic Cholestasis (PFIC) ≥12 months — both rare pediatric/adolescent cholestatic diseases — and CHOLBAM (cholic acid) — oral synthetic bile-acid replacement for ultra-rare bile-acid-synthesis disorders (acquired via 2020 Travere Therapeutics rights). Clinical pipeline: volixibat — another IBAT inhibitor (different molecule from maralixibat) — in Phase 3 for Primary Biliary Cholangitis (PBC) and Primary Sclerosing Cholangitis (PSC) — both adult chronic cholestatic liver diseases with much larger patient populations than ALGS/PFIC (PBC ~50K+ US, PSC ~30K+) — potentially transformative; earlier-stage pipeline including additional IBAT-related and selected adjacencies. Geography US-led commercial with expanding ex-US (EU LIVMARLI approval 2022). Capital structure transitioning from R&D-loss-funded by equity to self-funding as LIVMARLI scales. MIRM enters FY2026 with FY2025 revenue selected various aggregate ~$310-380M (~30-40% growth), aggregate adjusted EPS ~$(0.40)-0.80, adjusted EBITDA ~$10-50M, under Chris Peetz. The first thesis pillar is the LIVMARLI commercial franchise — ~$240-290M+ annual revenue and growing strongly: LIVMARLI is an oral once-daily small-molecule minimally absorbed IBAT inhibitor — works locally in the gut to block IBAT, preventing bile-acid reabsorption back to the liver and reducing systemic bile-acid levels — mechanism alleviates cholestatic pruritus (severe itching), the dominant disabling symptom in cholestatic liver diseases; FDA approvals — September 2021 for ALGS (≥3 months, first approved drug for ALGS pruritus — historically these patients had no therapeutic option for severe itching; ALGS rare autosomal-dominant JAG1/NOTCH2 disorder causing bile-duct paucity and chronic cholestasis from infancy/childhood); March 2024 for PFIC (≥12 months — group of rare inherited disorders causing severe early-onset cholestasis — PFIC types 1/2/3 from different genetic mutations) — competing with Ipsen's BYLVAY (odevixibat from 2023 Albireo acquisition); EU approval 2022 for ALGS; commercial model rare-disease specialty pricing (~$150-250K+/patient-year), small dedicated salesforce targeting pediatric hepatologists/gastroenterologists/transplant specialists, patient-finder/diagnostic-support programs (ALGS genetic testing, PFIC genetic-and-clinical screening); FY2025 dynamics are LIVMARLI revenue ~$240-290M+ (~25-35% growth on PFIC expansion + ALGS continued + ex-US), competitive dynamics with BYLVAY in PFIC (smaller pool — both gaining share from no-treatment baseline), ~95%+ gross margin, operating leverage improving, ex-US progressing; FY2026 catalyst is continued prescription growth (US + ex-US), ALGS patient identification, PFIC market development, additional indications (Mirum exploring Biliary Atresia + other pediatric cholestatic), operating-margin expansion through breakeven; risks/competitors are Ipsen/BYLVAY pressure in PFIC, payer pricing pressure, pediatric-population constraints, emergence of disease-modifying therapies; comp set Ipsen (IPN.PA, BYLVAY), Travere Therapeutics (TVTX), broader rare-disease Insmed (INSM), Argenx (ARGX), Ultragenyx (RARE), BridgeBio (BBIO), Krystal Biotech (KRYS), Crinetics (CRNX). The second pillar bundles CHOLBAM with volixibat plus broader cholestatic-disease pipeline: CHOLBAM (cholic acid) for rare inherited bile-acid-synthesis disorders (BASDs) — patients lacking functional bile-acid synthesis enzymes needing exogenous replacement — ~$30-50M annual revenue, profitable, small patient population, acquired via 2020 Travere deal; volixibat — oral once-daily minimally absorbed IBAT inhibitor (similar mechanism to maralixibat but different molecule with different properties — acquired via 2019 Lumena Pharmaceuticals asset acquisition) — in two Phase 3 programs: VANTAGE Phase 3 in PBC (adult chronic autoimmune cholestatic liver disease, ~50K+ US, ~150K+ global — current SOC is UDCA + obeticholic acid Ocaliva from Intercept + recently-approved seladelpar Livdelzi GSK/CymaBay + elafibranor Iqirvo Ipsen/Genfit — pruritus remains key disabling symptom inadequately addressed by current treatments — clear unmet need for IBAT inhibitor — volixibat targets pruritus plus possibly underlying progression) and VISTAS Phase 3 in PSC (adult chronic cholestatic disease ~30K+ US, currently no FDA-approved treatments — pruritus the disabling symptom) — volixibat Phase 3 data expected 2026 for both; pipeline opportunity — PBC ~$1-3B+ pruritus TAM alone, PSC smaller but unaddressed — success transformatively expands Mirum's TAM from rare pediatric (ALGS/PFIC) to adult chronic liver disease; broader pipeline — additional IBAT-related programs, cholestatic adjacencies, selective BD; FY2025 dynamics are CHOLBAM stable, volixibat VANTAGE/VISTAS Phase 3 progressing toward 2026 readouts, broader pipeline advancing, R&D intense; FY2026 catalyst is volixibat VANTAGE PBC Phase 3 readout (major asymmetric upside binary — positive with clean safety = transformative) and VISTAS PSC Phase 3 readout (smaller TAM but asymmetric upside), pipeline data, BD activity; risks are volixibat Phase 3 failure (efficacy/safety — IBAT inhibitors well-characterized class profile but specific molecules vary), competitive PBC landscape (GSK seladelpar, Ipsen elafibranor, Intercept Ocaliva — all address underlying disease, leaving room for pruritus-specific addition), pricing dynamics; comp set in PBC/PSC GSK (GSK, Livdelzi via CymaBay), Ipsen (IPN.PA, Iqirvo via Genfit), Intercept (now Alfasigma, Ocaliva), Eiger Biopharmaceuticals (EIGR); broader specialty universe. The capital story: commercial-stage transitioning to profitability — no dividend (cash to commercial + R&D + pipeline + capital strength), no buybacks of consequence (growth-investment mode with improving CF), cash ~$200-300M+ (replenished via follow-ons), minimal debt (essentially net-cash, no meaningful term loans or senior notes), FCF inflecting positive as LIVMARLI scales over relatively fixed cost base — approaching/has achieved operating-profitability though still investing in volixibat Phase 3 + broader pipeline; net loss narrowed substantially; ~50-55M shares (small float, meaningful historical dilution but issuance pace slowing as profitability emerges); capital priorities LIVMARLI commercial growth (US + ex-US) → volixibat Phase 3 trials + pipeline R&D → earlier-stage programs → potential bolt-on M&A (active acquirer — Travere rare-disease commercial 2020, Vencerx 2021 for cholestatic adjacencies) → maintain cash runway; with path to GAAP profitability, cash-runway/financing trajectory, and volixibat Phase 3 outcomes driving multi-year capital-allocation framework. At ~$55-80 per share on ~50-55M shares (~$3.0-4.4B equity, ~$2.8-4.2B EV given net-cash) MIRM trades at roughly ~8-12x EV/Sales — premium specialty/rare-disease pharma multiple reflecting LIVMARLI growth + volixibat PBC/PSC pipeline optionality + path to profitability + IBAT-platform strategic strength — versus Ipsen (IPN.PA, BYLVAY competitor), Insmed (INSM), Argenx (ARGX), Ultragenyx (RARE), BridgeBio (BBIO), Krystal Biotech (KRYS), Crinetics (CRNX), Travere (TVTX), Vanda (VNDA), Apellis (APLS). FY2026 base case: ~$360-430M+ revenue + ~$0.20-1.00 adj. EPS + LIVMARLI continued growth + ex-US ramp + volixibat Phase 3 data flowing + pipeline progressing + cash position stable; bull case: ~$400-500M+ revenue + ~$0.80-1.60+ adj. EPS on stronger LIVMARLI (PFIC expansion + ex-US + Biliary Atresia label), volixibat VANTAGE PBC Phase 3 positive (transformative — ~$1-3B+ TAM + 2027-2028 PBC launch), VISTAS PSC positive (additional optionality), and substantial re-rating; bear case: ~$280-330M revenue + ~$(0.60)-0.20 adj. EPS on Ipsen/BYLVAY PFIC share, payer pricing pressure, volixibat Phase 3 failure (major asymmetric downside — eliminates adult expansion), pipeline setbacks, and compression. The thesis depends on the LIVMARLI commercial pipeline (US prescription + ex-US + ALGS/PFIC expansion + Biliary Atresia + competitive defense vs BYLVAY) plus the CHOLBAM + volixibat + cholestatic-disease pipeline (CHOLBAM stable + volixibat VANTAGE PBC + VISTAS PSC + broader pipeline) plus path to profitability plus net-cash balance sheet plus Chris Peetz's continued founding-CEO execution.