Mirum Pharmaceuticals, Inc., Satiogen Pharmaceuticals, Inc., and Shire Human Genetic Therapies, Inc. (SHGT) filed Mirum Pharmaceuticals, Inc. et al. v. Zenara Pharma Private Limited et al., No. 1:26-cv-01154 (D. Del.), on September 14, 2026. The complaint says the suit follows Zenara's Paragraph IV notice letter dated August 4, 2026, received on or about August 5, 2026, for ANDA No. 221420. That application seeks approval of maralixibat chloride oral tablets, 10 mg, 15 mg, 20 mg, and 30 mg, as generic versions of LIVMARLI (maralixibat) tablets under NDA No. 219485. The complaint alleges, on information and belief, that Biophore India is Zenara's parent, that Zenara is its wholly owned subsidiary, that the companies collaborate on the ANDA products, and that Biophore India at least makes the active ingredient.

Patents and accused products

The complaint lists eight patents: U.S. Patents 10,512,657; 11,229,647; 11,229,661; 11,260,053; 11,376,251; 11,497,745; 12,350,267; and 12,296,050. It says each is listed in the Orange Book for LIVMARLI tablets at the 10 mg, 15 mg, 20 mg, and 30 mg base-equivalent strengths. The accused products are Zenara's ANDA products under ANDA No. 221420. Plaintiffs allege infringement under 35 U.S.C. § 271(e)(2) from submission of the ANDA, plus inducement and contributory infringement. The complaint says the proposed label is substantially identical to the LIVMARLI label, including the approved indications for cholestatic pruritus in patients 3 months of age and older with Alagille syndrome (ALGS) and in patients 12 months of age and older with progressive familial intrahepatic cholestasis (PFIC).

Asserted claims pleaded in the counts include independent claims 1-3 of the '657 patent, with the complaint addressing claims 1 and 3 together and claim 2 separately; independent claims 1 and 12 of the '647 patent; independent claim 1 of the '661 patent; independent claim 1 of the '053 patent; independent claims 1, 14, and 19 of the '251 patent; independent claim 1 of the '745 patent; independent claims 1, 2, and 20 of the '267 patent; and claims 1 and 17 of the '050 patent, with the label-use allegation aimed at claim 17. For the '657, '647, '661, '251, '745, and '267 patents, the complaint alleges that the notice letter did not assert that label-directed use would fail to meet limitations of the claims identified in those counts.

What the patents cover

U.S. Patent 10,512,657 (Bile acid recycling inhibitors for treatment of pediatric cholestatic liver diseases) covers methods of treating pediatric PFIC type 2, and related pruritus, with a specified apical sodium-dependent bile acid transporter inhibitor (ASBTI) or pharmaceutical composition that lowers serum or hepatic bile acids by at least 20%. Asserted claims: independent claims 1-3. Claim 1 covers treating or ameliorating pediatric PFIC2 by administering the specified ASBTI, or a pharmaceutically acceptable salt, in an amount effective to decrease serum and/or hepatic bile acid levels by at least 20% compared with pre-treatment levels. Claim 2 covers treating or ameliorating pruritus in a pediatric subject suffering from PFIC2 with that same ASBTI and bile-acid reduction requirement. Claim 3 covers the PFIC2 treatment method using a pharmaceutical composition that contains the specified ASBTI under the same bile-acid reduction requirement.

U.S. Patent 11,229,647 (Methods for treating cholestasis) covers pediatric ALGS treatment with maralixibat chloride at defined daily dose ranges. Asserted claims: independent claims 1 and 12. Claim 1 covers treating ALGS in a pediatric subject by administering maralixibat chloride at about 400 ug/kg/day to about 800 ug/kg/day. Claim 12 covers treating ALGS in a pediatric subject by administering maralixibat chloride at about 400 ug/kg/day. The complaint ties these claims to LIVMARLI labeling for cholestatic pruritus in ALGS and to label-directed tablet dosing.

U.S. Patent 12,296,050 (Pharmaceutical compositions comprising maralixibat and uses thereof) covers solid oral compositions of maralixibat with a defined excipient set, and methods of treating cholestatic pruritus with those compositions. Asserted claims: 1 and 17, with the label-use count aimed at claim 17. Claim 1 covers a pharmaceutical composition of maralixibat, or a pharmaceutically acceptable salt, with (i) a diluent selected from a listed group that includes lactose monohydrate and modified celluloses, (ii) a glidant selected from a listed group that includes silicon dioxide, (iii) glyceryl palmitostearate as the lubricant at about 6% to about 12% (w/w), and (iv) a disintegrant selected from a listed group that includes crospovidone, at about 1% to about 10% (w/w). Claim 17 covers a method of treating cholestatic pruritus by administering a therapeutically effective amount of the claim 1 composition. The complaint alleges that Zenara's detailed statement did not disclose the complete ANDA formulations, that the parties did not agree on confidential access to the ANDA before the statutory filing window closed, and that plaintiffs are using the suit and discovery to test whether the ANDA products fall within claims 1 and 17.

U.S. Patent 11,229,661 (Bile acid recycling inhibitors for treatment of pediatric cholestatic liver diseases) covers treating or ameliorating a pediatric disorder characterized by a non-truncating BSEP mutation. Asserted claim: independent claim 1. Claim 1 covers that method where the disorder is selected from PFIC2, benign recurrent intrahepatic cholestasis 2 (BRIC2), and drug-induced cholestasis, by administering a claimed ASBTI or a pharmaceutically acceptable salt.

U.S. Patent 11,260,053 (Bile acid recycling inhibitors and satiogens for treatment of diabetes, obesity, and inflammatory gastrointestinal conditions) covers increasing bile acid and bile-salt concentrations in the distal gastrointestinal tract. Asserted claim: independent claim 1. Claim 1 covers that increase by administering a claimed ASBTI so that a therapeutic amount is delivered to the distal ileum, the colon, or the rectum.

U.S. Patent 11,376,251 (Bile acid recycling inhibitors for treatment of pediatric cholestatic liver diseases) covers ASBTI treatment of pediatric Alagille syndrome and of pruritus in that setting. Asserted claims: independent claims 1, 14, and 19. Claim 1 covers treating or ameliorating Alagille syndrome in a pediatric subject by administering a claimed ASBTI or a pharmaceutically acceptable salt, solvate, or prodrug. Claim 14 covers that ALGS method using a pharmaceutical composition that contains the claimed ASBTI, or a pharmaceutically acceptable salt, solvate, or prodrug. Claim 19 covers treating or ameliorating pruritus in a pediatric subject suffering from Alagille syndrome by administering a claimed ASBTI or a pharmaceutically acceptable salt, solvate, or prodrug.

U.S. Patent 11,497,745 (Methods for treating cholestasis) covers maralixibat dosing for ALGS. Asserted claim: independent claim 1. Claim 1 covers treating ALGS in a subject in need of treatment by administering maralixibat at from 360 ug/kg/day to 880 ug/kg/day.

U.S. Patent 12,350,267 (Bile acid recycling inhibitors for treatment of pediatric cholestatic liver diseases) covers ASBTI treatment of pediatric PFIC and of pruritus in that setting. Asserted claims: independent claims 1, 2, and 20. Claim 1 covers treating or ameliorating PFIC in a pediatric subject by administering a claimed ASBTI or a pharmaceutically acceptable salt, solvate, or prodrug. Claim 2 covers treating or ameliorating pruritus in a pediatric subject with PFIC by administering a claimed ASBTI or a pharmaceutically acceptable salt. Claim 20 covers treating or ameliorating PFIC by administering to a pediatric subject a pharmaceutical composition that contains the claimed ASBTI, or a pharmaceutically acceptable salt, solvate, or prodrug.

What the lawsuit is about

Plaintiffs cast Zenara's tablet ANDA as a Paragraph IV challenge to the LIVMARLI Orange Book patents, spanning ASBTI methods for pediatric PFIC and ALGS, maralixibat dosing methods, and a maralixibat tablet composition patent. They allege that label-directed use of the ANDA products will induce and contribute to infringement of the method claims, and that commercial manufacture, use, offer for sale, or importation before expiry would infringe at least claims 1 and 17 of the '050 patent. The prayer asks the court to set any FDA approval date no earlier than the last patent expiry, including extensions and exclusivity, and to enjoin manufacture, use, sale, and importation of the ANDA products. The complaint also cites Mirum Pharmaceuticals, Inc. v. Annora Pharma Private Ltd., No. 1:25-cv-1537-JLH (D. Del.) (consolidated), which it describes as pending litigation over liquid maralixibat under ANDA No. 220917, and it cites an answer in that case as admitting that Biophore India is Zenara's parent.

What it means

This is a Delaware Hatch-Waxman case on generic LIVMARLI tablets, centered on ASBTI methods for pediatric cholestatic liver disease, maralixibat dosing for ALGS, and a tablet formulation patent. Expect validity and claim-scope fights over the recited ASBTI structures and dose ranges, composition discovery on the '050 patent, and coordination questions with Mirum's related Delaware liquid-maralixibat case.

What to watch next

Watch for Zenara and Biophore answers and any early invalidity or noninfringement contentions, including on the patents where the complaint says the notice letter did not contest claim limitations. Watch whether the court coordinates this tablet ANDA case with the related liquid-maralixibat Delaware matter. Also watch the approval stay. Plaintiffs' supplemental ANDA filing (D.I. 3, September 14, 2026) states a thirty-month stay deadline of March 29, 2029, and gives August 6, 2026 as the date the patentees received notice; the complaint says on or about August 5. March 29, 2029 is seven and a half years after FDA first approved LIVMARLI (NDA 214662) on September 29, 2021. Under 21 U.S.C. 355(j)(5)(F)(ii), when the drug carries new chemical entity exclusivity and the infringement suit is filed during the one-year period that begins four years after that approval, the thirty-month period runs until seven and a half years have passed from the approval. This suit was filed on September 14, 2026, inside that year, and the Orange Book lists the exclusivity as expiring September 29, 2026.