Mirum posts strong Phase 2b HDV data for brelovitug

Mirum Pharmaceuticals reported positive Phase 2b results from the AZURE-1 study of brelovitug in chronic hepatitis delta virus (HDV).

Rhea-AI Filing Summary

Mirum Pharmaceuticals reported positive Phase 2b results from the AZURE-1 study of brelovitug in chronic hepatitis delta virus (HDV). Among the first 53 patients evaluated at Week 24, virologic response was seen in 100% of patients on 300 mg weekly and 75% on 900 mg every four weeks, versus 0% in the delayed treatment arm.

The composite primary endpoint of virologic response plus ALT normalization was achieved by 45% and 35% of patients in the 300 mg and 900 mg arms, respectively, compared with 0% in the delayed arm. Treatment was generally well tolerated, with few grade 3 or higher and serious adverse events. Mirum plans to present full Phase 2b results at the EASL Congress in late May 2026 and expects topline data from Phase 3 AZURE-1 and AZURE-4 in H2 2026, with potential BLA submission and U.S. commercial launch in 2027.

Positive

• Compelling Phase 2b efficacy: brelovitug achieved 100% and 75% virologic response in the 300 mg QW and 900 mg Q4W arms, respectively, with 45% and 35% meeting the composite endpoint, versus 0% in the delayed treatment arm.
• Advancing toward registration: topline Phase 3 AZURE-1 and AZURE-4 data are expected in H2 2026 with a stated goal of potential BLA submission and U.S. commercial launch in 2027.

Negative

• None.

Insights

Biotech clinical development analyst

Strong mid-stage HDV data de-risk brelovitug and set up pivotal readouts in 2026.

The AZURE-1 Phase 2b results show brelovitug driving high virologic response rates in chronic HDV: 100% in the 300 mg weekly arm and 75% in the 900 mg every-four-weeks arm, versus 0% in the delayed treatment group at Week 24.

The composite endpoint combining virologic response and ALT normalization reached 45% and 35% in the active arms, again with 0% in controls. Safety appears manageable, with one grade 3+ event in the 300 mg arm and one serious adverse event in the 900 mg arm, and no treatment-related grade 3+ or serious events reported.

These data support advancing brelovitug as a single-agent HDV therapy. The company guides to topline Phase 3 AZURE-1 and AZURE-4 data in H2 2026, targeting potential BLA submission and U.S. launch in 2027. Subsequent disclosures from those pivotal studies will clarify registrational prospects and commercial potential.

8-K Event Classification

Item 8.01 — Other Events

1 item

Item 8.01 Other Events Other

Voluntary disclosure of events the company deems important to shareholders but not covered by other items.

Key Figures

Virologic response rate 300 mg QW: 100% Virologic response rate 900 mg Q4W: 75% Virologic response delayed arm: 0% +5 more

8 metrics

Virologic response rate 300 mg QW 100% AZURE-1 Phase 2b at Week 24, HDV RNA ≥2 log10 reduction or TND

Virologic response rate 900 mg Q4W 75% AZURE-1 Phase 2b at Week 24, HDV RNA ≥2 log10 reduction or TND

Virologic response delayed arm 0% AZURE-1 Phase 2b at Week 24, comparator group

Composite endpoint response 300 mg QW 45% Virologic response plus ALT normalization at Week 24

Composite endpoint response 900 mg Q4W 35% Virologic response plus ALT normalization at Week 24

Any adverse events 300 mg QW 11 of 21 (52%) Participants with any AE in active arm

Any adverse events 900 mg Q4W 10 of 20 (50%) Participants with any AE in active arm

Targeted U.S. launch year 2027 Potential BLA submission and commercial launch timeline

Key Terms

virologic response, alanine aminotransferase (ALT) normalization, Phase 2b, monoclonal antibody, +2 more

6 terms

virologic response medical

"100% of patients in the 300 mg once weekly (QW) arm and 75% ... achieved virologic response"

A virologic response is the measurable decline or disappearance of a virus in a patient after treatment, usually shown by lower levels of the virus in blood or tissues. For investors, it’s an early signal that an antiviral drug or vaccine is working—like seeing the smoke thin after firefighters start dousing a blaze—and strong, sustained responses can predict regulatory approval, broader use and commercial potential.

alanine aminotransferase (ALT) normalization medical

"the primary composite endpoint of virologic response and alanine aminotransferase (ALT) normalization was achieved"

Phase 2b medical

"the primary endpoint was met in the Phase 2b portion of the AZURE-1 study"

Phase 2b is a stage in the development of a new medicine or treatment where researchers test its effectiveness and safety in a larger group of people. This step helps determine whether the treatment works well enough to move forward and if it has manageable side effects, which is important for investors because successful results can lead to potential approval and market opportunity.

monoclonal antibody medical

"brelovitug, an investigational monoclonal antibody designed to bind hepatitis B surface antigen"

A monoclonal antibody is a laboratory-made protein designed to recognize and attach to a specific target in the body, such as a disease-causing substance or cell. It functions like a highly precise lock-and-key tool, helping to treat or detect illnesses. For investors, companies developing monoclonal antibodies can represent promising opportunities in the healthcare sector, especially as these treatments often address unmet medical needs.

hepatitis delta virus (HDV) medical

"for the treatment of chronic hepatitis delta virus (HDV)"

A virus that infects the liver and can only replicate when hepatitis B virus (HBV) is also present; HDV is a small, defective RNA virus that makes hepatitis B infections more severe and accelerates liver damage. It matters to investors because HDV drives drug development, clinical trial activity, regulatory review, and potential market demand for diagnostics and therapies in the liver-disease and biotech sectors—think of it as a specialty market segment tied to HBV.

biologics license application regulatory

"potential BLA submission and commercial launch in the U.S. in 2027"

A biologics license application is a formal request submitted to regulatory authorities seeking approval to market a new biological medicine, such as vaccines or treatments made from living organisms. It is a comprehensive review process that evaluates the safety, effectiveness, and manufacturing quality of the product. For investors, receiving approval signals that a biological therapy can be sold to the public, potentially leading to revenue growth and market success.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Mirum Pharmaceuticals (MIRM) announce about the AZURE-1 Phase 2b study?

Mirum Pharmaceuticals reported that the Phase 2b portion of the AZURE-1 study met its primary endpoint. Brelovitug showed strong antiviral activity and meaningful composite response rates in chronic HDV patients compared with a delayed treatment arm at Week 24 of therapy.

How effective was brelovitug in Mirum’s AZURE-1 Phase 2b HDV trial?

Brelovitug produced virologic responses in 100% of patients on 300 mg weekly and 75% on 900 mg every four weeks. The composite endpoint of virologic response plus ALT normalization was achieved in 45% and 35% of these arms, with 0% response in the delayed treatment arm.

What safety profile was observed for brelovitug in the AZURE-1 Phase 2b study?

Brelovitug was generally well tolerated across both active dose groups. Overall adverse events occurred in about half of treated participants, with very few grade 3 or higher or serious events reported and none of these higher-grade or serious events considered related to treatment.

When will Mirum (MIRM) share full Phase 2b AZURE-1 results for brelovitug?

Mirum plans to present full Phase 2b AZURE-1 data in a late-breaking poster at the European Association for the Study of the Liver Congress. That presentation is scheduled for May 27–30, 2026, providing a more detailed look at efficacy and safety outcomes.

What are Mirum Pharmaceuticals’ next steps for brelovitug after AZURE-1 Phase 2b?

Mirum is continuing Phase 3 AZURE-1 and AZURE-4 studies of brelovitug in chronic HDV. The company expects topline Phase 3 data in the second half of 2026 and is targeting potential BLA submission and U.S. commercial launch in 2027, subject to study outcomes and regulatory review.

What disease is brelovitug targeting in Mirum’s AZURE program?

Brelovitug is being developed to treat chronic hepatitis delta virus infection, a severe form of viral hepatitis. It is an investigational monoclonal antibody designed to bind hepatitis B surface antigen, aiming to reduce HDV replication and improve liver-related biomarkers such as ALT.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 04/27/2026 - 08:07 AM EDT Learn about SEC filing dates

false 0001759425 0001759425 2026-04-27 2026-04-27

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 27, 2026

Mirum Pharmaceuticals, Inc.

(Exact name of registrant as specified in its charter)

Delaware		001-38981		83-1281555
(State or other jurisdiction of incorporation)		(Commission File Number)		(IRS Employer Identification No.)

989 East Hillsdale Boulevard
Suite 300
Foster City, California				94404
(Address of principal executive offices)				(Zip Code)

Registrant’s telephone number, including area code: (650) 667-4085

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class		Trading Symbol(s)		Name of each exchange on which registered
Common stock, par value $0.0001 per share		MIRM		Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On April 27, 2026, Mirum Pharmaceuticals, Inc. (the “Company”) announced the primary endpoint was met in the Phase 2b portion of the AZURE-1 study evaluating brelovitug, an investigational monoclonal antibody designed to bind hepatitis B surface antigen (HBsAg), for the treatment of chronic hepatitis delta virus (HDV).

The Phase 2b portion of the AZURE-1 study included the first 53 patients evaluated at Week 24 of treatment.

At Week 24, treatment with brelovitug demonstrated robust antiviral activity across both dose groups. 100% of patients in the 300 mg once weekly (QW) arm and 75% of patients in the 900 mg once every four weeks (Q4W) arm achieved virologic response (≥2 log10 reduction in HDV RNA from baseline or undetectable HDV RNA [<LLOQ, TND]), as compared to 0% in the delayed treatment arm.

Consistent with these antiviral effects, the primary composite endpoint of virologic response and alanine aminotransferase (ALT) normalization was achieved in 45% and 35% of patients in the 300 mg QW and 900 mg Q4W arms, respectively, as compared to 0% of patients in the delayed treatment arm. After 24 weeks of treatment, further reductions in ALT and HDV RNA levels have been observed. These results support the potential of brelovitug as a single agent therapy to treat HDV.

The efficacy results by treatment arm in the Phase 2b portion of AZURE-1 at Week 24 are presented below in Key Efficacy Endpoints.

Treatment with brelovitug was well tolerated across dose groups. The safety profile summary is presented below in Summary of Safety.

The full results from the Phase 2b portion of the AZURE-1 study will be presented in a late-breaking poster presentation at the European Association for the Study of the Liver (EASL) Congress, May 27-30, 2026. Topline data from the Phase 3 AZURE-1 and AZURE-4 studies are expected in H2 2026, with potential BLA submission and commercial launch in the U.S. in 2027.

Key Efficacy Endpoints

Endpoint		300 mg QW (n=20)		900 mg Q4W (n=20)		Delayed Treatment Arm (n=12)
Virologic Response
(HDV RNA ≥2 log10 reduction or TND)		100%		75%		0%
HDV RNA <LLOQ, TND		30%		5%		0%
ALT Normalization		45%		40%		8%
Primary Endpoint
(Virologic Response + ALT Normalization)		45%		35%		0%
P-value*		0.003		0.024

Full analysis set, participants receiving at least one post baseline efficacy assessment

* P-values compare each treatment group against delayed treatment using a stratum-adjusted Cochran-Mantel-Haenszel (CMH) test.

2

Summary of Safety

Participants who experienced, n (%)		300 mg QW N=21				900 mg Q4W N=20				Delayed Treatment Arm N=12
AEs
Any			11 (52)				10 (50)				3 (25)
Related to treatment			7 (33)				7 (35)				0
Grade 3+
Any			1 (5)†				0				0
Related to treatment			0				0				0
Serious
Any			0				1 (5)#				0
Related to treatment			0				0				0
AE Leading to Discontinuation of study drug			0				0				0
Injection site reactions			3 (14)				4 (20)				0
Flu-like Symptoms			0				1 (5)				0

^†  Grade 3 AE of musculoskeletal pain, not related

^#  Hospitalization for liver cirrhosis, class B, in a patient with recent history of ascites and hypoalbuminemia, not related and resolved

Forward-Looking Statements

Certain statements contained in this report are forward-looking statements that involve a number of risks and uncertainties. Such forward-looking statements include, without limitation, statements regarding the potential benefits of brelovitug and the expected timing of topline data for the AZURE studies and potential BLA submission and commercial launch. The inclusion of forward-looking statements should not be regarded as a representation by the Company that any of these results will be achieved. Actual results may differ from those set forth in this report due to the risks and uncertainties associated with research and development of pharmaceutical product candidates, as well as risks and uncertainties inherent in the Company’s business, including those described in the Company’s other filings with the U.S. Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof, and the Company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement. This caution is made under the safe harbor provisions of Section 21E of the Private Securities Litigation Reform Act of 1995.

3

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

				Mirum Pharmaceuticals, Inc.
Date: April 27, 2026				By:		/s/ Christopher Peetz
						Christopher Peetz
						Chief Executive Officer

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