Mirum Pharmaceuticals (MIRM) Q3 2026 earnings review
Mirum raises its sales outlook, while trial costs widen losses
Mirum Pharmaceuticals, a rare-disease drugmaker, grew sales quickly and won key clinical trials, but heavy research spending pushed it into a deep loss. Product sales rose 40% from a year ago to $186 million, or 45% by our math when excluding a one-time partner order last year, beating what the prior plan pointed to. Chief executive Chris Peetz raised the full-year outlook for a third time, as the US regulator approved bone-disease drug Atebrioz and Phase 3 trials for Livmarli and hepatitis drug brelovitug succeeded.
| Product sales (excluding prior-year one-off order) | +45% reported sales: $185.7M (+40% from a year ago) |
|---|---|
| Livmarli sales | $133.4M +45% from a year ago (+53% excluding one-off order) |
| Operating loss | $59.7M $2.6M operating profit a year ago |
| Full-year product sales outlook | Raised $27.5M middle of the range: $717.5M (+38% growth) |
⚖️ Verdict: 🟢 Bullish
The story got better because three clinical wins and an approval reduced the pipeline risk behind Mirum's $771 million bet on hepatitis drug brelovitug. One caution: trial costs for that programme and launch spending pushed the operating loss to $60 million and trimmed the cash balance by $61 million.
The question now is whether regulators will accept the five planned drug filings in the first half of 2027 without demanding extra trials that prolong the cash burn. Bulls point to positive Phase 3 readouts and Breakthrough designations, while sceptics note the regulator previously recommended a Phase 3 trial for liver drug volixibat. Fourth-quarter AZURE-4 hepatitis data and FDA feedback on the volixibat filing package will decide.
🐂 Bull Case
FDA Approved Atebrioz and Three Drug Trials Succeeded
Mirum spent $771 million earlier this year to buy brelovitug, an experimental antibody for hepatitis delta virus (HDV, a severe liver infection), and licensed Atebrioz for a rare bone disease. Critics warned that packing several late-stage readouts into two quarters created binary risk for that spending. Chief executive Chris Peetz said the third quarter brought "the approval and launch of ATEBRIOZ and positive Phase 3 results across our late-stage rare liver portfolio."
- Atebrioz: approved by the US regulator and launched "to reduce the volume of total new heterotopic ossification (HO) in adult and pediatric patients aged 12 years and older with fibrodysplasia ossificans progressiva (FOP)", a genetic condition where muscle turns into bone
- Atebrioz pediatric study: positive results in children aged 6 to under 12, setting up a filing in the first half of 2027
- Brelovitug AZURE-1 Phase 3: met its main goal in chronic HDV, while 48-week Phase 2b data showed "deepening viral suppression and increased rates of alanine aminotransferase (ALT) normalization", a measure of liver injury
- Livmarli EXPAND Phase 3: arrived a quarter early and "met the primary endpoint and achieved statistical significance across all prespecified secondary endpoints" in additional rare liver diseases
These results clear the first clinical hurdle for the Bluejay acquisition and open up "five potential upcoming approvals and label expansions", Peetz said. What to watch: topline data from the second Phase 3 HDV trial, AZURE-4, due in the fourth quarter of 2026. The company's planned first-half 2027 approval filing for brelovitug remains "subject to supportive AZURE-4 results".
Existing Liver Drugs Prompted a Third Outlook Raise
Mirum sells Livmarli, an oral medicine for severe itching in two rare pediatric liver conditions, alongside two older bile acid medicines, Cholbam and Ctexli. The rare-disease drugmaker is counting on newly diagnosed adult patients to keep Livmarli growing while its newer drugs launch. Third-quarter net product sales reached $185.7 million, up 39.6% from a year ago and 5.0% above what the prior full-year plan implied by our math.
A year ago, third-quarter Livmarli sales included about $5 million from a one-time partner order by Takeda. Excluding that order, underlying Livmarli revenue grew 53.0% from a year ago by our math, compared with the 45% headline rate, though its quarter-on-quarter gain slowed to $4.7 million. Meanwhile, Bile Acid Medicines rose 28% to $52.3 million, speeding up from 20% growth in the first half. Management raised the full-year sales forecast by $27.5 million at the middle of the range.
What to watch: whether fourth-quarter sales top the $195.7 million implied by the full-year outlook. Beating that figure would extend Mirum's record of finishing every year above its raised target.
Retired 2029 Convertible Notes Reduced Interest Costs
In May, the California biotech refinanced most of its 4.00% debt due in 2029 with 0.00% notes due in 2032, leaving a smaller stub that holders could convert while total debt and share count remained a concern for investors. In the third quarter, Mirum repurchased $20.0 million of those remaining 2029 notes, representing about 25% of the leftover balance, so quarterly interest expense dropped to $1.6 million from $3.6 million a year ago.
The company ended September with $500.5 million in cash and investments against $731.3 million in convertible debt, while stock issued for acquisitions and refinancing lifted the basic share count 29.4% from a year ago. What to watch: convertible notes and holdback liabilities in the fourth-quarter balance sheet. Settling remaining obligations in cash rather than shares would cap dilution ahead of the 2027 filings.
🐻 Bear Case
Research Spending More Than Doubled and Erased Operating Profit
Mirum highlights its commercial momentum and financial independence, and aims to generate positive operating cash flow in 2027 and accounting profit in 2028. However, the cost of running late-stage trials and building a larger sales force pushed the company from a $2.6 million operating profit a year ago to a $59.7 million operating loss this quarter. Even excluding a $13.5 million one-time upfront research charge, the operating loss widened to $46.2 million by our math.
- Research and development (cost of clinical trials): 58.1% of revenue ($107.9 million), up 25.8 percentage points from a year ago, including $42.1 million for brelovitug
- Selling, general and administrative (sales and overhead): 47.8% of revenue ($88.9 million), up 1.3 percentage points from a year ago
- Commercial cash contribution margin (product sales less cash cost of sales and cash overhead): 47.1% by our math, down from the high 50s in the second quarter
- Unrestricted cash and investments: $500.5 million, down $60.9 million from June
Trial spending on brelovitug jumped from $28.8 million in the second quarter to $42.1 million in the third, while cash overhead rose to fund the Atebrioz launch. What to watch: quarterly brelovitug research spending in the first half of 2027. If trial costs do not fall after the HDV approval filing, reaching positive operating cash flow in 2027 will be difficult.
Risks this quarter didn't answer
Six standing concerns from prior quarters received no new details in the third-quarter earnings release.
- Volixibat regulatory path in primary sclerosing cholangitis (PSC, a chronic adult liver disease): the release still plans an approval filing in the first half of 2027, without saying if the US regulator dropped its prior recommendation for a Phase 3 study.
- Atebrioz launch figures and clinical data: the release gave no drug price, patient start count, or publication date for the pivotal PROGRESS study.
- Livmarli sales breakdown: management still does not split revenue between Alagille syndrome and progressive familial intrahepatic cholestasis (PFIC), nor between adult and pediatric patients.
- International order swings: the release did not quantify periodic distributor or Takeda orders, which will be detailed in the quarterly filing.
- Patent and generic challenges: four generic drugmakers are challenging Livmarli patents ahead of a 2028 trial, and Cholbam lacks patent protection; the quarterly filing's legal note will carry any updates.
- Bluejay acquisition governance: no process or payout details were added regarding a director-affiliated fund's stake in Bluejay.
💲 Other KPIs
Accounts receivable — money owed by customers and distributors for delivered drugs — rose 7.6% from last quarter by our math, outpacing the 5.4% sequential rise in product sales. Over the first nine months of 2026, receivables grew 26.8% from $123.3 million at year-end, tying up working capital as international and specialty pharmacy sales expanded.
Employee stock awards rose 83.8% from $18.1 million a year ago and increased from $30.6 million in the second quarter. Stock-based pay equalled 17.9% of product sales this quarter, up from 13.6% a year ago, adding non-cash expense that widens the gap between cash flow and accounting profit.
🔮 Guidance
Raised. The middle of the full-year sales plan moved up $27.5 million, pointing to 38.0% growth for 2026 by our math. That leaves about $195.7 million for the fourth quarter, or 32.5% growth from a year ago and 5.3% above the third quarter. It is the third raise this year: +$30M, +$20M, +$27.5M. If the two-year pattern of beating the final range by 2.1% holds, full-year sales would reach $732 million.
❓ Key Questions
Did operating cash flow stay positive in Q3?
The earnings release did not include a cash flow statement. Total cash and investments fell by $60.9 million during the quarter, even after accounting for $20.0 million in debt repurchases and $13.5 million in upfront research charges.
Has the FDA agreed to a PSC filing without Phase 3?
Mirum still plans to submit volixibat for primary sclerosing cholangitis in the first half of 2027. Last quarter, management disclosed that the regulator had recommended an additional Phase 3 trial before filing.
What are the price and initial patient numbers for Atebrioz?
The company launched Atebrioz for fibrodysplasia ossificans progressiva during the quarter, but the release did not disclose the drug's net price, how many trial patients switched to paid therapy, or how much revenue it contributed.
Why did Livmarli's quarterly dollar gain slow to $4.7 million?
Livmarli added $4.7 million over the second quarter, down from a $14.9 million sequential gain in the prior period. Investors need to know whether international ordering patterns or slower patient additions caused the change.