Rare Diseases Today—March 26, 2026

This week’s Rare Diseases update highlights regulatory designations, new approvals, advancing clinical programs, and expanding access partnerships across neurological, genetic, metabolic, and autoimmune conditions.

In Today’s Newsletter

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🧬 Venglustat earns FDA Breakthrough Therapy status in Gaucher disease [1] [US • 18 Mar 2026]

https://www.sanofi.com/en/media-room/press-releases/2026/2026-03-18-06-00-00-3257888
Context: LEAP2MONO Phase 3 compared oral venglustat with imiglucerase; neurological improvements were measured using a composite score including ataxia and cognition assessments.
Key point: Venglustat (Sanofi; glucosylceramide synthase inhibitor) received FDA Breakthrough Therapy designation for neurological manifestations of type 3 Gaucher disease based on Phase 3 LEAP2MONO data showing improvement vs enzyme replacement therapy.
Implication: May accelerate regulatory review and development of a therapy targeting neurological symptoms of Gaucher disease.

🎯 GSK’s B7-H3 ADC gains orphan designation for SCLC in Japan [2] [JP • 23 Mar 2026]

https://www.gsk.com/en-gb/media/press-releases/gsk-s-b7-h3-targeted-antibody-drug-conjugate-risvutatug-rezetecan-granted-orphan-drug-designation-for-small-cell-lung-cancer-in-japan/
Context: The designation is supported by early clinical data from the Phase 1 ARTEMIS-001 trial showing durable responses in patients with extensive-stage SCLC (n not stated).
Key point: Risvutatug rezetecan (GSK; B7-H3-targeted antibody-drug conjugate) received Orphan Drug Designation in Japan for small-cell lung cancer.
Implication: Signals pipeline investment and modality expansion.

🧴 Dupixent approved in Japan for bullous pemphigoid [3] [JP • 24 Mar 2026]

https://investor.regeneron.com/news-releases/news-release-details/dupixentr-dupilumab-approved-japan-first-targeted-medicine-treat
Context: In the LIBERTY-BP-ADEPT Phase 2/3 trial, more patients achieved sustained disease remission at Week 36 compared with placebo while receiving corticosteroids.
Key point: Dupixent (dupilumab; Regeneron and Sanofi) was approved in Japan for adults with moderate-to-severe bullous pemphigoid, becoming the first targeted therapy for the disease in the country.
Implication: May influence prescriber choice and payer reviews pending full data.

💊 UCB selects PANTHERx for KYGEVVI distribution [4] [US • 23 Mar 2026]

https://www.prnewswire.com/news-releases/pantherx-rare-selected-by-ucb-as-the-exclusive-specialty-pharmacy-for-the-distribution-of-kygevvi-302722321.html
Context: The pharmacy will support patient access through its RxARECARE model, including education, insurance navigation, and therapy-specific care management.
Key point: UCB selected PANTHERx Rare as the exclusive specialty pharmacy for KYGEVVI (doxecitine and doxribtimine) for TK2 deficiency, a rare mitochondrial disease.
Implication: May expand screening, initiation, and follow-up at scale.

👁️ Orsini becomes single-source pharmacy partner for Glaukos’ Epioxa [5] [US • 23 Mar 2026]

https://www.prnewswire.com/news-releases/orsini-to-serve-as-single-source-specialty-pharmacy-partner-for-glaukos-epioxa-302719843.html
Context: Epioxa received FDA approval in October 2025 and enables a corneal cross-linking procedure without removal of the corneal epithelium.
Key point: Orsini was selected as the single-source specialty pharmacy partner for Epioxa (Glaukos), a corneal cross-linking therapy for keratoconus.
Implication: May expand screening, initiation, and follow-up at scale.

🧠 Zorevunersen shows seizure and developmental improvements in Dravet syndrome [6] [18 Mar 2026]

https://www.fiercebiotech.com/biotech/beyond-seizures-stokes-experimental-drug-aims-restore-developmental-loss-dravet-syndrome
Context: Open-label data across two trials and a long-term extension involved 81 patients with Dravet syndrome; improvements were observed in Vineland-3 adaptive behavior scores (n not specified).
Key point: Zorevunersen (Stoke Therapeutics with Biogen; antisense oligonucleotide targeting SCN1A) demonstrated seizure reduction and improvements in adaptive behavior measures in Phase 1/2 studies.
Implication: May influence prescriber choice and payer reviews pending full data.

🧬 Sarepta seeks full approval for Duchenne exon-skipping therapies [7] [US • 19 Mar 2026]

https://investorrelations.sarepta.com/news-releases/news-release-details/sarepta-provides-regulatory-update-amondys-45r-and-vyondys-53r
Context: Submissions will include Phase 3 ESSENCE confirmatory data and real-world evidence supporting the exon-skipping therapies in Duchenne muscular dystrophy.
Key point: Sarepta plans to submit supplemental NDAs seeking conversion of accelerated approvals to traditional approvals for AMONDYS 45 (casimersen) and VYONDYS 53 (golodirsen).
Implication: Introduces regulatory scrutiny that may affect long-term market positioning of exon-skipping therapies.

🧪 Shionogi launches Phase 2 study of oral therapy for Pompe disease [8] [JP • 19 Mar 2026]

https://www.businesswire.com/news/home/20260319711940/en/Shionogi-Announces-First-Patients-Enrolled-in-Global-Phase-2-Clinical-Trial-in-Adults-with-Late-Onset-Pompe-Disease
Context: The Esprit trial is a randomized, placebo-controlled, double-blind study assessing safety and preliminary efficacy of S-606001 alongside enzyme replacement therapy over 52 weeks.
Key point: Shionogi enrolled the first patients in a global Phase 2 trial evaluating S-606001, an investigational oral substrate-reduction therapy for late-onset Pompe disease.
Implication: Signals pipeline investment and modality expansion.

Why it matters

Rare disease innovation continues expanding, with new regulatory designations and clinical programs targeting neurological, metabolic, and genetic conditions.
RNA- and gene-modulating approaches such as antisense oligonucleotides are gaining traction in severe pediatric disorders.
Specialty pharmacy partnerships remain critical for complex rare-disease therapies that require patient support and access coordination.
Regulators increasingly consider real-world evidence, particularly for ultra-rare diseases with small trial populations.

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FAQ

What is venglustat and why did the FDA grant Breakthrough Therapy designation?

Venglustat (Sanofi) is an oral glucosylceramide synthase inhibitor designed to reduce lipid accumulation in Gaucher disease. Phase 3 data showed neurological improvements compared with enzyme replacement therapy in type 3 Gaucher disease, prompting FDA Breakthrough Therapy designation. [1]

What is risvutatug rezetecan targeting in cancer?

Risvutatug rezetecan (GSK) is an antibody-drug conjugate targeting the B7-H3 protein, which is expressed on multiple solid tumors. Early clinical data in the ARTEMIS-001 trial showed responses in extensive-stage small-cell lung cancer. [2]

Why is Dupixent approval in bullous pemphigoid significant?

Dupixent (dupilumab; Regeneron and Sanofi) is the first targeted therapy approved in Japan for bullous pemphigoid. The decision was supported by the LIBERTY-BP-ADEPT trial showing higher sustained remission rates versus placebo. [3]

What makes zorevunersen different from current Dravet syndrome treatments?

Zorevunersen (Stoke Therapeutics with Biogen) aims to increase NaV1.1 protein production by targeting SCN1A gene expression, potentially addressing the disease’s underlying cause rather than only controlling seizures. [6]

What is the regulatory status of Sarepta’s Duchenne drugs?

AMONDYS 45 and VYONDYS 53 currently have accelerated approval in the U.S. Sarepta plans to submit supplemental NDAs seeking conversion to full approval using confirmatory study data and real-world evidence. [7]

How does Shionogi’s Pompe therapy differ from existing treatments?

S-606001 is designed as an oral substrate-reduction therapy that inhibits glycogen synthase to limit glycogen buildup. Current standard treatment relies on enzyme replacement therapy to increase glycogen breakdown. [8]

Entities / Keywords

Sanofi (venglustat, Gaucher disease)
GSK (risvutatug rezetecan, B7-H3 ADC)
Regeneron / Sanofi (Dupixent, dupilumab)
Stoke Therapeutics / Biogen (zorevunersen, Dravet syndrome)
Sarepta Therapeutics (AMONDYS 45, VYONDYS 53, Duchenne muscular dystrophy)
Shionogi / Maze Therapeutics (S-606001, Pompe disease)
UCB / PANTHERx Rare (KYGEVVI, TK2 deficiency)
Glaukos / Orsini (Epioxa, keratoconus)