Five Key Startups Shining the Light on Rare Diseases

Growing product pipelines and government support for rare disease treatments is expected to drive the growth of the global market by 11.6% per year from $216.2 billion in 2024 to $374.4 billion by 2030.

Many rare disease treatments in the market are biologics, with one example being Sanofi’s Dupixent (dupilumab), which was greenlit by the U.S. Food and Drug Administration (FDA) in June this year for the treatment of adult patients with a condition called bullous pemphigoid. However, of the more than 10,000 known rare diseases affecting 400 million people across the globe, only 5% of those conditions have an approved treatment, leaving a lot of room for more innovation.

Rare diseases are generating interest from big pharma companies, with notable examples including the $1.05 billion acquisition of France’s Amolyt Pharma by the U.K.’s AstraZeneca in 2024 and Germany-based Merck KGaA’s buyout of SpringWorks Therapeutics in the U.S. for $3.4 billion in April 2025.

As investors flock to promising rare disease startups, check out our list of the top five investor favorites for their potential to bring new rare disease treatments to the market.

Actio Biosciences

Founded: 2021 | Headquarters: San Diego, California

Actio Biosciences, whose name was derived from the Latin word actio meaning “action,” aims to translate genetic insights into precision medicines.

Actio currently focuses on researching small molecule treatments for rare genetic disorders, with the long-term goal of applying its expertise to more common complex conditions.

Actio’s Phase I-stage program ABS-0781 is designed to treat an incurable rare condition called Charcot-Marie-Tooth disease type 2C (CMT2C). This disease is driven by mutations in a gene called TRPV4 that encodes an ion channel, and has symptoms like muscle weakness, vocal cord paralysis, and respiratory complications. Daily oral doses of ABS-0781 are designed to block the TRPV4 channel and restore the patient’s motor functions.

Its second treatment candidate, ABS-1230, is designed to treat a rare and often fatal form of epilepsy caused by mutations to a gene called KCNT1, which encodes a different ion channel. By doing this, the preclinical-stage drug could clamp down on overactive ion channels and target the root cause of the disease.

Actio has raised $121 million to date, including a $55 million Series A round in 2023 and a $66 million Series B in June 2025, which was co-led by Regeneron Ventures and Deerfield Management.

Actio plans to launch the healthy volunteer portion of a Phase I clinical trial of ABS-1230 this year, with a Phase Ib study planned in 2026.

Aeovian Pharmaceuticals

Founded: 2012 | Headquarters: Berkeley, California

Originally founded as Delos Pharmaceuticals, Aeovian Pharmaceuticals was incubated at the Buck Institute for Research on Aging in the U.S. The startup is developing treatments for rare genetic and age-related diseases by focusing on a protein called mechanistic target of rapamycin complex (mTORC).

mTORC forms complexes called mTORC1 and mTORC2 to regulate a range of cellular processes. However, these regulators become imbalanced in diseases like refractory epilepsy associated with tuberous sclerosis complex (TSC), where mTORC1 becomes hyperactive and leads to seizures that are often resistant to existing therapies.

Aeovian’s lead program, AV078 is in Phase I testing for the treatment of TSC refractory epilepsy, and is designed to selectively inhibit mTORC1. This makes it safer than less selective mTORC inhibitors.

Earlier-stage selective mTORC1 inhibitors in Aeovian’s pipeline include AV805 for neurodegenerative diseases and AV505 for metabolic disorders, in addition to programs with a different target for the treatment of undisclosed conditions.

In March 2024, Aeovian raised $50 million in a financing led by the Saudi Arabian-U.S. non-profit organization Hevolution Foundation, with participation from venture capital investors and the German biotech Evotec.

Azafaros

Founded: 2018 | Headquarters: Leiden, Netherlands

Azafaros is researching drugs for rare metabolic disorders like lysosomal storage disorders, which comprise rare conditions that collectively affect 1 in 5,000 births.

Lysosomal storage disorders are mostly caused by mutations to proteins essential to transporting and processing sugars, proteins, and lipids, which lead to neurodegenerative symptoms and damage to organs like the liver, spleen, heart, and kidneys. While some of the conditions have specific therapies, many patients can only receive palliative care.

Azafaros’ pipeline is based on research from Leiden University and Amsterdam UMC, with its lead program nizubaglustat beginning two Phase III studies for the treatment of Niemann-Pick disease type C and GM1/GM2 gangliosidoses in July 2025.

Nizubaglustat is a modified sugar molecule that can be taken orally and reach the brain to cut down on the buildup of harmful waste lipids and alleviate disease symptoms.

Azafaros bagged €25 million ($29 million) in a Series A round in 2020. This was followed by a huge Series B round worth €132 million ($155 million) in May 2025 to finance its Phase III program and expand its pipeline to different conditions. The round was co-led by Jeito Capital and Forbion Growth.

Glycomine

Founded: 2014 | Headquarters: San Carlos, California

Glycomine is developing therapies for rare metabolic conditions that lack treatments. Its lead candidate GLM101 is in Phase II development for the treatment of phosphomannomutase 2-congenital disorder of glycosylation (PMM2-CDG), also known as CDG-1A or CDG Type 1a.

In PMM2-CDG, a mutation in an enzyme called PMM2 impairs the production of a molecule called mannose-1-phosphate, which is essential for proper protein structure and function. This leads to a wide range of symptoms like muscle weakness, liver disease, cardiomyopathy, and coagulopathies.

GLM101, which showed promising interim results in March 2024, is designed to replace the missing mannose-1-phosphate and bypass the PMM2 mutations.

Glycomine raised $12 million and $68 million in Series A and B rounds in 2016 and 2021, respectively. It then landed an impressive $115 million in a Series C round in April 2025, which was led by CTI Life Sciences Fund, abrdn Inc, and Advent Life Sciences, with the capital used to finance the clinical testing of GLM101.

Glycomine has also collected the largest single clinical dataset of PMM2-CDG from a natural history study in 139 patients, which each patient having completed more than two years in the study as of 2023.

Healx

Founded: 2014 | Headquarters: Cambridge, U.K.

Healx arose when its founders, one of them a co-inventor of Viagra, were inspired by Beacon, a patient group set up to find treatments for a rare genetic disorder called alkaptonuria faced a long and expensive drug discovery process.

Healx specializes in using generative artificial intelligence and working with patient groups to design new treatments for rare diseases more quickly and cheaply than traditional methods of drug development. Its platform, called Healnet, analyzes millions of data points in the scientific literature to generate 10–20 potential drug candidates by the end of the discovery phase.

The startup dosed the first patient in a Phase II trial of its oral lead candidate HLX-1502 in patients with a genetic condition called neurofibromatosis type 1 (NF1) in February this year. Its pipeline also includes treatments for conditions like pediatric oncology, fragile X syndrome, and Angelman syndrome.

Healx raised $10 million in a Series A round in 2018, $56 million in a Series B round in 2019, and $47 million in a Series C round in August 2024. The C round was co-led by R42 Group in the U.S. and Atomico in the U.K. and will fuel pipeline development.

In November 2024, Healx launched an agreement with Sanofi to identify new potential indications for a late stage discontinued asset that is being considered for out-licensing. Healx also partnered with SCI Ventures to discover and develop treatments for spinal cord injury in July this year.

Jonathan Smith, PhD, is a freelance science journalist based in the U.K. and Spain. He previously worked in Berlin as a reporter and news editor at Labiotech, a website covering the biotech industry. Prior to this, he completed a PhD in behavioral neurobiology at the University of Leicester and freelanced for the U.K. organizations Research Media and Society of Experimental Biology. He has also written for medwireNews, Biopharma Reporter, and Outsourcing Pharma.