Rare Diseases Today—February 19, 2026

This is the weekly update in the rare disease field, summarizing the latest regulatory actions, clinical progress, data releases, and industry developments. Key updates include FDA decisions, new approvals, and advances in treatments for rare conditions.

In Today’s Newsletter

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🧠 FDA rejects bitopertin for erythropoietic protoporphyria [1] [US • 13 Feb 2026]

https://www.fiercebiotech.com/biotech/fda-rejects-discs-rare-disease-drug-despite-commissioners-voucher
Context: FDA’s complete response letter (CRL) for bitopertin, a treatment for erythropoietic protoporphyria (EPP), citing concerns over the use of a surrogate endpoint (protoporphyrin levels) instead of clinical outcomes.
Key point: Bitopertin showed modest results but did not demonstrate improved sun tolerance, a key symptom of EPP.
Implication: Disc aims to address the FDA’s concerns with ongoing Phase 3 trials using clinical outcomes as primary endpoints.

💉 NICE recommends pegzilarginase for ultra-rare ARG1 deficiency [2] [UK • 17 Feb 2026]

https://www.openaccessgovernment.org/nice-recommends-first-disease-modifying-treatment-for-ultra-rare-arg1-deficiency/205163/
Context: NICE recommends pegzilarginase as the first disease-modifying treatment for arginase-1 deficiency (ARG1-D) in England, based on clinical evidence of its efficacy in reducing blood arginine levels.
Key point: Pegzilarginase offers new hope for patients with this progressive metabolic condition, which affects approximately 20 individuals in England.
Implication: This recommendation could significantly improve patient outcomes and quality of life.

🧬 HCB101 earns FDA Orphan Drug Status in gastric cancer [3] [US • 13 Feb 2026]

https://www.targetedonc.com/view/hcb101-novel-fusion-protein-earns-fda-orphan-drug-status-in-gastric-cancer
Context: HCB101, a novel anti-SIRPα-CD47 fusion protein, has received orphan drug designation for gastric cancer, a rare and aggressive disease.
Key point: Early trials suggest reduced side effects and promising tumor control in advanced stages.
Implication: The orphan drug designation supports HCB101’s development as a potential treatment for gastric cancer, with further clinical investigations underway.

💊 Biohaven CEO criticizes FDA red tape in rare disease treatments [4] [US • 13 Feb 2026]

https://www.fiercebiotech.com/biotech/its-really-dire-time-patients-biohaven-ceo-says-fda-red-tape-blocking-access-rare-disease
Context: Biohaven’s CEO, Vlad Coric, highlights FDA rejections as part of a broader issue affecting rare disease treatments, citing the company’s struggles with its spinocerebellar ataxia (SCA) therapy.
Key point: Despite positive real-world evidence, Biohaven’s SCA therapy was rejected by the FDA, which raised concerns about clinical trial design and evidence validity.
Implication: The company’s focus on real-world evidence for rare disease treatments may face additional challenges, affecting future submissions.

🫁 Essential Pharma strengthens rare disease portfolio with Ventavis® acquisition [5] [EU • 17 Feb 2026]

https://uk.finance.yahoo.com/news/essential-pharma-strengthens-rare-disease-120000642.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8
Context: Essential Pharma acquires Ventavis® (iloprost trometamol), a treatment for primary pulmonary hypertension, expanding its rare disease portfolio.
Key point: Ventavis® will provide essential support to patients with this rare condition, delivered via a nebulizer to improve blood flow and reduce strain on the heart.
Implication: This acquisition boosts Essential Pharma’s presence in rare cardiovascular and pulmonary diseases, reinforcing its commitment to niche medical conditions.

💉 PTC Therapeutics withdraws NDA for Translarna™ in DMD [6] [US • 12 Feb 2026]

https://ir.ptcbio.com/news-releases/news-release-details/ptc-therapeutics-provides-regulatory-update-translarnatm-2
Context: PTC Therapeutics withdraws its New Drug Application for Translarna™ (ataluren) after the FDA raised concerns about the effectiveness data for Duchenne muscular dystrophy (DMD).
Key point: Despite over two decades of research, the FDA indicated that the data did not meet the required thresholds for approval.
Implication: PTC will reevaluate its approach and plans to resubmit with additional data.

🧬 UCB’s Kygevvi receives positive CHMP opinion for TK2d [7] [EU • 13 Feb 2026]

https://pmlive.com/pharma_news/ucbs-kygevi-receives-positive-chmp-opinion-for-thymidine-kinase-2-deficiency/
Context: Kygevvi, developed by UCB, received a positive opinion from the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) for the treatment of thymidine kinase 2 deficiency (TK2d).
Key point: The treatment shows promise for patients with this extremely rare and fatal mitochondrial disease.
Implication: The European Commission’s final decision on Kygevvi is expected later in 2026, which could pave the way for an important new treatment.

Why it matters

FDA rejection of Disc’s bitopertin underscores the importance of clinical evidence over surrogate endpoints in rare disease drug approvals [1].
NICE recommendation of pegzilarginase is a significant step forward for patients with ARG1-D, setting a precedent for future rare disease treatments in the NHS [2].
HCB101’s orphan drug status emphasizes growing interest in innovative treatments for gastric cancer, with a focus on reduced side effects and enhanced immune response [3].
Biohaven’s appeal against FDA rejection highlights ongoing challenges with the FDA’s evolving stance on real-world evidence and its impact on rare disease therapies [4].
Essential Pharma’s acquisition of Ventavis® strengthens its rare disease portfolio, benefiting pulmonary hypertension patients with limited treatment options [5].
PTC Therapeutics’ NDA withdrawal for Translarna™ signals continued struggles in the rare disease space, despite extensive research efforts [6].
UCB’s Kygevvi for TK2d offers hope for patients suffering from this rare and fatal disease, with a positive CHMP opinion advancing its approval process in Europe [7].

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FAQ

Why did the FDA reject Disc’s bitopertin?

The FDA cited concerns over the use of a surrogate endpoint (protoporphyrin levels) in place of clinical outcomes like sun tolerance, which is crucial for EPP patients [1].

What did NICE recommend for ARG1-D?

NICE recommended pegzilarginase for routine use in the NHS for treating ARG1-D, the first disease-modifying therapy for this condition [2].

What’s the status of HCB101 in gastric cancer?

HCB101 has received FDA Orphan Drug Designation, with early trials showing promising tumor control and safety in advanced gastric cancer patients [3].

Why did Biohaven criticize the FDA?

Biohaven’s CEO expressed frustration over the FDA’s rejection of its SCA therapy, despite positive real-world evidence and earlier discussions with the agency about its clinical design [4].

What is the significance of Essential Pharma’s acquisition of Ventavis®?

Ventavis® expands Essential Pharma’s portfolio for rare pulmonary hypertension, offering a crucial treatment for patients in need of effective therapy [5].

What led to the withdrawal of PTC Therapeutics’ NDA for Translarna™?

PTC withdrew the NDA after the FDA indicated that the clinical evidence did not meet the necessary threshold for approval in Duchenne muscular dystrophy [6].

What is the status of Kygevvi in TK2d?

Kygevvi received a positive opinion from the CHMP for treating thymidine kinase 2 deficiency, with final approval expected in 2026 [7].

Entities / Keywords

Disc Medicine; bitopertin; erythropoietic protoporphyria; FDA CRL • NICE; pegzilarginase; arginase-1 deficiency; NHS • HCB101; gastric cancer; orphan drug status • Biohaven; spinocerebellar ataxia; FDA rejection • Essential Pharma; Ventavis®; pulmonary hypertension • PTC Therapeutics; Translarna™; Duchenne muscular dystrophy • UCB; Kygevvi; thymidine kinase 2 deficiency; CHMP.