Mirum Pharmaceuticals, Inc. (MIRM) Earnings

Management highlights

- Corporate Strategy & Positioning * Mirum is focused on building a leading rare disease biopharma business targeting underserved, overlooked patient populations * The company holds a strong capital position with positive operating cash flow from commercial operations, enabling continued investment in pipeline development, potential upcoming launches, and opportunistic strategic business development * Completed a $690 million 0% coupon convertible notes offering in Q2, generating $672 million in net proceeds, settling 75% of outstanding 2029 notes, adding $197 million in cash to the balance sheet, and reducing interest expense to extend financial flexibility - Commercial Operations * Strong commercial execution across the existing portfolio drove higher-than-expected Q2 sales growth * Zilurgisertib for fibrodysplasia ossificans progressiva (FOP) has a PDUFA date of September 2026, with the NDA proceeding as expected after a successful late-cycle meeting with the FDA; Mirum is fully prepared for a potential Q4 2026 U.S. launch, leveraging its existing rare genetics sales team that already serves the concentrated specialized treatment centers for FOP * A marketing authorization application for Zilurgisertib has been submitted in Europe, with updates to come as the review progresses - Pipeline & Regulatory Updates * Volixibat for cholestatic pruritus due to primary sclerosing cholingitis (PSC): The VISTAS pivotal trial met its primary endpoint with highly statistically significant improvements in pruritus, and the FDA granted breakthrough therapy designation after the pre-NDA meeting. During the pre-NDA meeting, a new FDA review team recommended an additional Phase 3 trial, despite prior alignment on VISTAS as a pivotal study. Mirum plans to engage in iterative discussions with the FDA to supplement the existing VISTA data package, delaying the NDA submission target to H1 2027 * Volixibat for cholestatic pruritus due to primary biliary cholangitis (PBC): The VANTAGE pivotal study has completed enrollment with over 330 randomized patients, and the FDA has confirmed VANTAGE will be accepted as a pivotal trial if successful, with top-line results expected in Q1 2027 * Volovitug: Top-line Phase III AZURE-1 results expected in Q3 2026, with AZURE-4 results expected in Q4 2026, keeping the BLA submission target for H1 2027 on track * EXPAND study of Livmarli for additional rare cholestatic conditions: Top-line results expected in Q4 2026, positioning for a potential supplemental NDA in 2027 * MRN-338 for fragile X syndrome: Proof-of-concept data expected in 2027

Guidance

- Mirum upgraded its full year 2026 net product sales guidance from its prior range to $680 million to $700 million, driven by better-than-expected Q2 commercial performance across the existing portfolio - The updated full year 2026 sales guidance does not include any potential revenue from Zilurgisertib, as any launch in Q4 2026 would generate minimal revenue in 2026, with sales starting meaningfully in 2027 - Volixibat NDA submission for PSC is now targeted for H1 2027, delayed from the prior 2026 timeline - All other pipeline milestones remain on track: AZURE-1 top-line in Q3 2026, AZURE-4 and EXPAND top-line in Q4 2026, BLA submission for volovitug in H1 2027, VANTAGE top-line in Q1 2027, and MRN-338 proof-of-concept in 2027

Segment performance

Mirum has two core commercial product segments: 1. Livmarli (rare liver disease therapy): Net product sales of $129 million in Q2 2026, accounting for 73.3% of total Q2 net product sales. The U.S. contributed $92 million of this total, and international markets contributed $37 million. Growth is driven by durable new patient starts for Alagille syndrome, increasing new diagnoses for progressive familial intrahepatic cholestasis (PFIC), and growing demand from undiagnosed adult PFIC patients. 2. Bile acid medicines (rare genetic disease therapy): Net product sales of $48 million in Q2 2026, accounting for 27.3% of total Q2 net product sales, delivering steady consistent contributions to overall revenue. Total company net product sales for Q2 2026 were $176 million, a 37.5% increase from $128 million in Q2 2025.

Risks & headwinds

- Regulatory uncertainty for the volixibat PSC NDA: The FDA's unexpected request for an additional Phase 3 trial from a new review team, despite prior alignment on VISTAS as a pivotal study, creates delay and submission approval risk that could push commercial launch further out than currently planned * There is risk of a refuse-to-file decision if Mirum cannot align with the FDA on the adequacy of the existing VISTA data package during upcoming iterative discussions - Uncertainty regarding the FDA review team's specific rationale for requesting an additional Phase 3, as the request was not specific to safety or efficacy, creating ambiguity for Mirum's planning - All clinical trials carry inherent risk that trial results will not meet primary or secondary endpoints, delaying or derailing planned regulatory submissions and launches

Analyst Q&A

• Q: Is there any read-through from the BOLD study of odevixibat in biliary atresia to Mirum's upcoming EXPAND study of Livmarli? What key topics will Mirum address in upcoming discussions with the FDA on the volixibat PSC NDA? /

  A: The BOLD study and EXPAND study ask very different clinical questions. BOLD evaluates early acute biliary atresia patients for bilirubin reduction and transplant-free survival, while EXPAND evaluates pruritus in older biliary atresia patients, where IBAT inhibitors have already shown consistent efficacy across multiple indications, so there is no meaningful read-through between the two. The main priority for upcoming discussions is educating the new FDA review team on the extensive history of VISTAS: the study was designed with prior FDA alignment on all key elements including duration, endpoints, and analysis plan, and Mirum will walk through the robust existing dataset to demonstrate its adequacy for approval.

• Q: What was the FDA's rationale for requesting an additional Phase 3 for volixibat PSC, and is there regulatory precedent for approval based on the VISTAS trial design? /

  A: The FDA did not provide specific rationale, only general comments on efficacy that VISTAS already clearly addresses, and minor questions on safety that are already evaluated and addressed within the VISTAS design. There is clear regulatory precedent for this approach: prior approval of Livmarli for Alagille syndrome and PBC pruritus relied on similarly sized randomized controlled trial designs matching VISTAS, aligned with prior FDA agreements. The recent granting of breakthrough therapy designation after the pre-NDA meeting gives Mirum a strong framework to resolve disagreements.

• Q: Is there any regulatory read-through from the PSC situation to the VANTAGE study for PBC, and what is the status of Zilurgisertib launch preparation? /

  A: There is no read-through to VANTAGE. Mirum received explicit written confirmation from the FDA after granting breakthrough designation that VANTAGE, with its adjusted size of over 330 patients and agreed analysis plan, will be accepted as a pivotal trial if results are positive. Zilurgisertib launch preparation is progressing well: all FOP patients in the U.S. are already concentrated at ~300 identified specialized centers, Mirum leverages its existing rare genetics sales team to avoid additional overhead, and all pre-launch activity like account profiling and provider outreach is complete in preparation for a potential Q4 launch.

• Q: Could FDA accept a post-approval confirmatory study instead of a new pre-approval Phase 3 for volixibat PSC, what is Mirum's base case, and why is H1 2027 achievable? /

  A: Discussions have not progressed to the specifics of post-approval requirements, but pruritus is accepted as a valid endpoint for full approval, so any post-approval requirement would likely be a long-term safety registry rather than a confirmatory Phase 3. Mirum's base case is that the existing VISTAS data (the largest ever trial in PSC pruritus with clear positive efficacy and adequate safety data) is sufficient for approval, and the company is confident iterative discussions with the FDA will resolve the disagreement, allowing submission in H1 2027. The timeline accounts for multiple rounds of discussion, as the submission itself is largely ready now.