## What's Driving Mirum Pharmaceuticals' Strong Market Momentum?

**Mirum Pharmaceuticals** [MIRM](/market-activity/stocks/mirm) stock jumped 7.1% last week following the company's announcement of solid preliminary financial results and an ambitious development roadmap that captured investor attention. The pharmaceutical firm's strategic expansion in rare liver disease treatment appears to be resonating with the market, particularly as it broadens its therapeutic portfolio.

## Breaking Down the Numbers: 2025 Performance

The company delivered full-year 2025 net product sales reaching approximately $520 million, exceeding the previously guided range of $500-$510 million provided last November. This outperformance reflects strong market acceptance across Mirum's diversified product lineup.

Livmarli (maralixibat), the company's flagship product—an oral ileal bile acid transporter inhibitor designed for patients with cholestatic pruritus and related rare liver conditions—generated an estimated $359 million in revenue throughout 2025. The drug holds regulatory approval for cholestatic pruritus treatment in Alagille syndrome patients globally, with additional clearances for specific progressive familial intrahepatic cholestasis cases in both U.S. and European markets.

The company's commercial portfolio was significantly strengthened through its 2023 acquisition of **Travere Therapeutics'** [TVTX](/market-activity/stocks/tvtx) bile acid franchise, which brought Cholbam capsules and Ctexli tablets into the fold. These acquired assets contributed approximately $161 million in net sales for the year, with Q4 2025 alone generating roughly $43 million. Livmarli's fourth-quarter performance reached $106 million, bringing total Q4 revenue to approximately $149 million.

Financially, Mirum's balance sheet strengthened to $392 million in cash, cash equivalents, and marketable securities as of December 31, 2025, compared to $378 million three months prior. Over the trailing six months, MIRM shares appreciated 75.7%, substantially outpacing the broader biotech sector's 23.2% gain.

## 2026 Guidance and Pipeline Acceleration

Management projects full-year 2026 net product sales of $630-$650 million, signaling confidence in continued commercial growth and potential new product contributions.

The development pipeline reflects intentional expansion in rare liver disease treatment. Mirum is advancing Livmarli through the phase III EXPAND trial, evaluating its efficacy in treating cholestatic pruritus across additional rare cholestatic conditions. Study enrollment should conclude during the first half of 2026, with topline results expected in Q4 2026.

Volixibat, the company's most advanced pipeline candidate, remains in parallel phase IIb evaluations. The VANTAGE study examines this compound in primary biliary cholangitis patients, while the VISTAS study focuses on primary sclerosing cholangitis. Enrollment in VANTAGE is targeted for completion in H2 2026, with VISTAS data anticipated during Q2 2026.

In December, Mirum committed to acquiring Bluejay Therapeutics, a privately held biotech firm, with deal closure expected imminently. This transaction grants Mirum rights to brelovitug, a fully human monoclonal antibody in late-stage development for chronic hepatitis delta virus. The acquisition strategically deepens Mirum's rare liver disease expertise.

Additionally, the company recently initiated a phase II study evaluating MRM-3379, a newly in-licensed PDE4D inhibitor, for Fragile X syndrome treatment—an indication that extends Mirum's reach into rare genetic neurocognitive disorders.

## Competitive Context and Investment Perspective

Mirum carries a Zacks Rank #3 (Hold) designation. Within the biotech sector, **Alkermes** [ALKS](/market-activity/stocks/alks) and **Krystal Biotech** [KRYS](/market-activity/stocks/krys) both hold higher Zacks Rank #1 (Strong Buy) ratings. Over 60 days, Alkermes' 2026 EPS estimates expanded from $1.54 to $1.80, with shares gaining 6.9% over six months and three of four recent earnings beats. Krystal Biotech's 2026 EPS guidance rose to $8.49 from $8.34, and KRYS stock has surged 87.9% over six months, also demonstrating three positive earnings surprises in four recent quarters.

Mirum's trajectory in treating cholestatic pruritus and expanding rare liver disease indications positions it distinctly within a specialized therapeutic niche where long-term commercial potential appears underappreciated relative to near-term pipeline milestones.