Mirum Pharmaceuticals Reports Strong Third-Quarter 2026 Results, Raises Full-Year Sales Guidance and Advances Rare Disease Pipeline
Mirum Pharmaceuticals, Inc., a biopharmaceutical company focused on developing and commercializing treatments for rare diseases, has reported its financial results for the third quarter of 2026, highlighting continued commercial growth, progress across its late-stage clinical programs and several important regulatory milestones. The company generated global net product sales of $185.7 million during the quarter and raised its full-year 2026 net product sales guidance to between $715 million and $720 million.
The third quarter was a significant period for Mirum, marked by the U.S. Food and Drug Administration (FDA) approval and commercial launch of ATEBRIOZ® (zilurgisertib), positive Phase 3 findings from its rare liver disease portfolio and continued development of investigational therapies targeting chronic hepatitis delta virus (HDV), primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and other rare conditions.
The company’s commercial performance was supported by growth in LIVMARLI® (maralixibat) and its Bile Acid Medicines portfolio. At the same time, clinical progress across several programs expanded the number of potential regulatory and commercial opportunities expected over the next several years.
“The third quarter was an important period of execution for Mirum, with the approval and launch of ATEBRIOZ and positive Phase 3 results across our late-stage rare liver portfolio,” said Chris Peetz, Chief Executive Officer of Mirum.
Peetz highlighted positive results from the AZURE-1 study of brelovitug, which is being developed for chronic HDV, and additional data expected to be presented at the American Association for the Study of Liver Diseases (AASLD) The Liver Meeting. He also pointed to the EXPAND study results supporting the potential expansion of LIVMARLI to additional rare cholestatic liver diseases, including biliary atresia.
“Together with continued momentum across our commercial business, these milestones position Mirum for another meaningful inflection with five potential upcoming approvals and label expansions,” Peetz added.
Commercial Business Delivers Growth Across Key Products
Mirum reported global net product sales of $185.7 million for the third quarter of 2026, compared with $133.0 million in the corresponding period of 2025. The increase reflects continued demand for the company’s marketed rare disease treatments, particularly LIVMARLI and its Bile Acid Medicines portfolio.
LIVMARLI generated net product sales of $133.4 million during the third quarter, representing 45% growth compared with the third quarter of 2025. The medicine is part of Mirum’s rare liver disease business and is being evaluated for additional indications through the company’s clinical development program.
The strong quarterly performance highlights the contribution of LIVMARLI to Mirum’s commercial operations. The company’s efforts to expand the medicine’s potential use across additional rare cholestatic conditions could create further opportunities if supported by regulatory review and approval.
The Bile Acid Medicines portfolio recorded net product sales of $52.3 million in the third quarter of 2026, representing 28% growth compared with the same period last year. Growth across this portfolio, alongside the performance of LIVMARLI, contributed to the company’s overall revenue increase.
Based on its commercial performance and business outlook, Mirum raised its full-year 2026 net product sales guidance to $715 million to $720 million. The updated guidance reflects the company’s confidence in its commercial portfolio and the continued contribution of its marketed medicines.
The company’s strategy combines the growth of existing products with investment in new therapies for rare diseases. This approach is intended to build a broader commercial portfolio while advancing clinical programs that could address conditions with limited treatment options.
FDA Approves and Mirum Launches ATEBRIOZ for Fibrodysplasia Ossificans Progressiva
One of the most significant milestones during the third quarter was the U.S. FDA approval of ATEBRIOZ (zilurgisertib), followed by its commercial launch.
ATEBRIOZ is approved to reduce the volume of total new heterotopic ossification (HO) in adults and pediatric patients aged 12 years and older with fibrodysplasia ossificans progressiva (FOP).
FOP is an ultra-rare and severely disabling genetic condition characterized by the abnormal formation of bone in soft tissues, including muscles, tendons and ligaments. This process, known as heterotopic ossification, can progressively restrict movement and affect a patient’s ability to perform everyday activities.
The abnormal bone formation associated with FOP can result in substantial physical limitations over time. Patients may experience progressive loss of mobility as new bone develops in areas where it does not normally occur. The disease can also affect quality of life and create significant long-term care needs.
The approval of ATEBRIOZ represents an important addition to the treatment landscape for patients with FOP. Its authorized use focuses on reducing the volume of new heterotopic ossification in eligible patients aged 12 years and older.
Following the approval, Mirum initiated the commercial launch, adding a new product to its rare disease portfolio. The company is also evaluating the treatment in younger pediatric patients through the PROGRESS clinical program.
Positive PROGRESS Study Results in Younger Pediatric Patients
Mirum reported positive results from Cohort 2 of the PROGRESS study, which evaluated ATEBRIOZ in pediatric patients aged 6 to under 12 years with FOP.
The study is intended to support the development of the treatment for younger children who are not currently covered by the approved age range. Expanding treatment availability to this population could represent an important opportunity, given the progressive nature of FOP and the potential impact of abnormal bone formation during childhood.
Based on the positive Cohort 2 findings, Mirum plans to submit a supplemental New Drug Application (sNDA) to the U.S. FDA in the first half of 2027 to seek expansion of the ATEBRIOZ indication to pediatric patients aged 6 to under 12 years.
The planned regulatory submission represents one of several expected milestones that could broaden the company’s commercial reach in rare diseases.
LIVMARLI EXPAND Phase 3 Study Meets Primary and Secondary Endpoints
Mirum also reported positive Phase 3 results from the EXPAND study of LIVMARLI (maralixibat), which evaluated the medicine in additional rare cholestatic conditions, including biliary atresia.
The study met its primary endpoint and achieved statistical significance across all prespecified secondary endpoints. These findings provide clinical support for the potential expansion of LIVMARLI into additional patient populations affected by rare cholestatic liver diseases.
Cholestatic liver diseases are characterized by impaired bile flow. Bile is produced by the liver and plays an important role in digestion and the elimination of certain substances from the body. When bile flow is disrupted, bile-related components can accumulate in the liver and contribute to inflammation, tissue damage and other complications.
Biliary atresia is a rare and serious condition that affects the bile ducts, which carry bile from the liver to the small intestine. In affected children, the bile ducts become blocked or are absent, preventing normal bile drainage. The condition can lead to progressive liver damage and may require significant medical intervention.
The EXPAND results are important for Mirum because they support the potential use of an existing commercial product in additional rare cholestatic conditions. If the data support a successful regulatory submission and approval, the company could expand the number of patients eligible for LIVMARLI treatment.
Mirum plans to submit a supplemental New Drug Application for LIVMARLI in the first half of 2027. The planned submission will seek to advance the potential expansion of the medicine into the additional rare cholestatic conditions evaluated in the EXPAND program.
The results also reinforce the company’s broader strategy of using its established rare liver disease expertise to develop treatment options across multiple related conditions.
Brelovitug Advances Through Late-Stage Development for Chronic HDV
Another major development during the quarter was the positive Phase 3 AZURE-1 study of brelovitug in patients with chronic hepatitis delta virus infection.
Mirum reported that the AZURE-1 study met its primary endpoint, providing an important clinical milestone for the investigational treatment. Chronic HDV is a serious viral liver disease that occurs in individuals who are also infected with hepatitis B virus. The infection can lead to severe liver inflammation and an increased risk of progressive liver disease.
HDV is considered one of the more severe forms of viral hepatitis because of its potential to accelerate liver damage. Patients with chronic infection may face an increased risk of developing advanced liver disease and related complications.
The positive AZURE-1 results strengthen the development program for brelovitug and support its potential as a treatment option for people living with chronic HDV.
Mirum plans to present the full AZURE-1 Phase 3 results in a late-breaking poster presentation at the AASLD The Liver Meeting on November 8, 2026, at 1:00 p.m. Mountain Time. The presentation is expected to provide further details about the study outcomes and the treatment’s clinical performance.
The company also reported positive 48-week data from the Phase 2b portion of the AZURE-1 study. These findings demonstrated deepening viral suppression and increased rates of alanine aminotransferase (ALT) normalization.
ALT is an enzyme found primarily in the liver, and elevated levels in the bloodstream can indicate liver-cell injury. Normalization of ALT levels can therefore provide a useful measure of improvement in liver inflammation or injury, although it must be interpreted alongside other clinical measures.
The 48-week findings suggest that antiviral activity continued to develop over the treatment period, with deeper viral suppression and a higher proportion of patients achieving ALT normalization.
Full results from the Phase 2b portion are scheduled for an oral presentation at The Liver Meeting on November 8 at 2:00 p.m. Mountain Time.
In addition to the clinical progress, brelovitug received U.S. FDA Orphan Drug Designation for HDV. Orphan Drug Designation is intended to encourage the development of medicines for rare diseases and may provide certain regulatory and development incentives.
Mirum’s progress with brelovitug represents a central component of its late-stage pipeline strategy. The company is preparing for additional clinical data and regulatory milestones that could determine the next steps toward commercialization.
Upcoming Brelovitug Milestones Include AZURE-4 and Potential BLA Filing
Mirum expects to report topline data from the AZURE-4 Phase 3 study of brelovitug in chronic HDV during the fourth quarter of 2026.
The AZURE-4 results will be an important upcoming milestone for the program, as the company continues to build the clinical evidence needed to support a potential regulatory application.
Subject to supportive AZURE-4 results, Mirum plans to submit a Biologics License Application (BLA) for brelovitug in the first half of 2027. A BLA is a regulatory submission seeking authorization to market a biological product in the United States.
The planned filing remains dependent on the outcome of the AZURE-4 study and the overall clinical and regulatory assessment of the available data. If the program advances successfully, brelovitug could become another commercial product within Mirum’s rare liver disease portfolio.
Volixibat Programs Target PBC and PSC
Mirum is also advancing volixibat, an investigational therapy being developed for rare cholestatic liver diseases, including primary biliary cholangitis and primary sclerosing cholangitis.
The company expects to report topline results from the Phase 2b VANTAGE study of volixibat in primary biliary cholangitis during the first quarter of 2027.
PBC is a chronic autoimmune liver disease that affects the small bile ducts within the liver. Damage to these ducts can interfere with bile flow and result in the accumulation of bile-related substances, potentially causing progressive liver injury.
PSC is another chronic cholestatic liver disease involving inflammation and scarring of the bile ducts. The condition can affect both the ducts inside and outside the liver and may lead to progressive liver damage.
Both diseases can create substantial long-term health challenges, and treatment development remains an important area of research in rare liver disease.
In addition to the VANTAGE study, Mirum plans to submit a New Drug Application for volixibat in PSC during the first half of 2027. The planned submission represents another potential regulatory milestone for the company’s liver disease pipeline.
The development of volixibat across PBC and PSC reflects Mirum’s focus on conditions where additional treatment options may address significant unmet medical needs.
MRM-3379 Continues Development in Fragile X Syndrome
Beyond its liver disease and FOP programs, Mirum is developing MRM-3379 for fragile X syndrome (FXS).
Fragile X syndrome is a genetic condition associated with intellectual and developmental disabilities. It can affect learning, communication, behavior and other aspects of daily functioning.
Mirum is evaluating MRM-3379 in the Phase 2 BLOOM study. The company expects to report topline results from the study in 2027.
The program adds a neurological and genetic disease focus to Mirum’s broader pipeline, which is primarily centered on rare liver conditions and other serious rare disorders.
Leadership Appointment Strengthens Medical Organization
During the third quarter, Mirum announced the appointment of Rob Myers, M.D., as Chief Medical Officer.
The appointment comes as the company advances several late-stage clinical programs and prepares for multiple regulatory submissions. With potential applications and label expansions planned across its portfolio, medical leadership will remain important in overseeing clinical development, interpreting trial results and supporting interactions with regulatory authorities.
The appointment also coincides with a period of increased clinical activity, including the recent ATEBRIOZ approval, the positive EXPAND results and the Phase 3 progress of brelovitug.
Third-Quarter Financial Performance and Operating Expenses
Mirum reported total revenue of $185.7 million for the quarter ended September 30, 2026, compared with $133.0 million for the same period in 2025.
The company recorded total operating expenses of $245.5 million in the third quarter of 2026, compared with $130.4 million in the corresponding quarter of the previous year.
The reported operating expenses included several components associated with commercial operations, research and development, acquired assets and non-cash accounting expenses.
Cost of sales was $27.9 million, excluding intangible amortization and stock-based compensation expense. Selling, general and administrative expenses were $70.4 million, excluding stock-based compensation expense.
Research and development expenses totaled $93.6 million, excluding stock-based compensation expense. This amount included $42.1 million allocated to the development of brelovitug, reflecting the company’s investment in advancing its chronic HDV program.
Mirum also recorded a non-recurring acquired in-process research and development (IPR&D) expense of $13.5 million. In addition, the quarter included $40.0 million in stock-based compensation, intangible amortization and other non-cash expenses.
The increase in operating expenses compared with the prior-year period reflects the company’s expanded commercial and clinical development activities, including investment in multiple late-stage programs and the launch of ATEBRIOZ.
Although higher operating expenses reflect the resources required to support the company’s growth strategy, Mirum’s commercial revenue and cash position provide important context for evaluating its ability to fund ongoing operations and clinical development.
Cash Position and Convertible Notes Repurchase
Mirum reported unrestricted cash, cash equivalents and investments of $500.5 million as of September 30, 2026, compared with $391.4 million as of December 31, 2025.
The increased cash and investment balance provides the company with financial resources to support commercial operations, research and development programs and anticipated regulatory activities.
During the quarter, Mirum also repurchased $20.0 million in aggregate principal amount of its 4.00% convertible senior subordinated notes due 2029. The repurchased amount represented approximately 25% of the outstanding notes.
The transaction reduced the amount of these convertible notes remaining outstanding and formed part of the company’s capital and financial management activities.
The combination of its cash position, commercial revenue and financing actions is expected to support Mirum as it continues to advance several potential regulatory milestones. The company described its financial position as supporting continued business execution and financial independence.
Multiple Potential Regulatory Milestones Expected Through 2027
Mirum’s upcoming development schedule includes several important clinical and regulatory events:
- Fourth quarter 2026: Topline results from the Phase 3 AZURE-4 study of brelovitug in chronic HDV.
- First quarter 2027: Topline results from the Phase 2b VANTAGE study of volixibat in PBC.
- First half 2027: Planned NDA submission for volixibat in PSC.
- First half 2027: Planned sNDA submission for LIVMARLI based on the EXPAND program.
- First half 2027: Planned sNDA submission for ATEBRIOZ to expand its indication to pediatric patients aged 6 to under 12 years.
- First half 2027: Potential BLA submission for brelovitug, subject to supportive AZURE-4 results.
- 2027: Expected topline results from the Phase 2 BLOOM study of MRM-3379 in fragile X syndrome.
These milestones represent multiple opportunities to expand the company’s commercial portfolio and bring additional therapies to patients with rare diseases. The anticipated regulatory submissions are subject to clinical data, regulatory review and other applicable requirements.
Business Update Conference Call
Mirum scheduled a conference call for November 3, 2026, at 1:30 p.m. Pacific Time / 4:30 p.m. Eastern Time to discuss its third-quarter financial performance, recent business developments and clinical pipeline progress.
Participants can join using the following dial-in details:
- U.S. toll-free: +1 833 461 5787
- International: +1 585 542 9983
- Access code: 414267773
The webcast is available through the Investors section of the company’s corporate website at Mirum Pharmaceuticals Investor Relations. An archived version of the webcast will also be available for replay.
Mirum’s third-quarter 2026 performance reflects progress across both its commercial portfolio and clinical development operations. Revenue growth from LIVMARLI and Bile Acid Medicines supported the company’s decision to raise its full-year net product sales guidance to $715 million to $720 million.
The approval and launch of ATEBRIOZ added another treatment to the company’s rare disease portfolio, while positive results from the EXPAND and AZURE-1 studies strengthened the development outlook for LIVMARLI and brelovitug. The company is also preparing for upcoming data from volixibat and MRM-3379, extending its pipeline across several rare and serious conditions.
With $500.5 million in unrestricted cash, cash equivalents and investments at the end of September 2026, Mirum reported a financial position intended to support its commercial activities and planned clinical and regulatory work.
The next phase will depend on the results of ongoing studies, regulatory reviews and the company’s ability to translate clinical progress into approved treatment options. If the anticipated milestones are achieved, Mirum could move toward multiple approvals and label expansions through 2027, further broadening its presence in rare disease treatment.
About LIVMARLI® (maralixibat) oral solution and LIVMARLI® (maralixibat) tablets
LIVMARLI® (maralixibat) is an orally administered, ileal bile acid transporter (IBAT) inhibitor approved by the U.S. Food and Drug Administration for two pediatric cholestatic liver diseases. It is approved for the treatment of cholestatic pruritus in patients with Alagille syndrome (ALGS) in the U.S. three months of age and older and in Europe for patients two months of age and older. It is also approved in the U.S. for the treatment of cholestatic pruritus in patients with progressive familial intrahepatic cholestasis (PFIC) 12 months of age and older and in Europe for the treatment of PFIC in patients three months of age and older. For more information for U.S. residents, please visit LIVMARLI.com.
LIVMARLI has received Breakthrough Therapy designation for ALGS and PFIC type 2 and orphan designation for the treatment of ALGS and PFIC. In October 2026, Mirum announced that the Phase 3 EXPAND study of maralixibat in additional rare cholestatic liver diseases, including biliary atresia, met its primary endpoint of improvement in cholestatic pruritus and all prespecified secondary endpoints with statistical significance.