Healing that goes beyond skin deep.Giving fragile skin the strength it was meant to have.

For hundreds of thousands of people living with Epidermolysis Bullosa Simplex, there has never been a treatment that addresses the cause of their condition. Until now.

Learn about the disease →

The Disease

Butterfly children.

Children born with Epidermolysis Bullosa Simplex have skin so fragile that the slightest friction — putting on shoes, holding a pencil, being held by a parent — causes liquid-filled blisters, open wounds, and excruciating pain.

The disease is caused by mutations in the keratin genes that form the structural scaffolding of skin cells. Without functional keratin, the cells collapse under the mildest mechanical stress. The skin tears. It blisters. It shears.

"There is no cure. There is no approved treatment that addresses the underlying cause. For decades, the only option has been wound management — bandages changed daily, infections fought, pain endured."

EBS is lifelong, life-limiting, and profoundly isolating. It affects every stage of development — physical, emotional, social, and financial. For families, it is a daily ordeal of caregiving that most people cannot imagine.

A young girl living with Epidermolysis Bullosa, smiling alongside her mother — the daily reality of a child and carer living with EB

~500K

People affected worldwide

~70%

Of all EB cases are EBS

Zero

Approved treatments for the cause

Daily

Pain, wound care, and isolation

The Unmet Need

No one has ever treated the cause.

While three therapies have been approved for other forms of EB since 2023, Epidermolysis Bullosa Simplex — the most common form — has been left behind. Every existing approach manages symptoms. None addresses the structural failure at the heart of the disease.

A structural disease

EBS is caused by mutations in keratin 5 or keratin 14. The intermediate filaments that give skin cells their mechanical strength collapse, leaving cells unable to withstand even gentle friction.

A lifetime of management

Current care is entirely palliative: wound dressings, pain relief, infection control, nutritional support. There is no treatment that restores the skin's ability to hold itself together.

A category waiting for change

The EB community — patients, families, clinicians, and charities — has been waiting decades for a therapy that moves beyond management toward genuine healing.

A New Approach

From managing wounds to rescuing skin integrity.

Mariposa Therapeutics is building the first therapy that doesn't just manage the consequences of EBS — it addresses the structural failure itself. We are shifting this category from palliation to healing.

Today's Reality

Symptom management

× Wound dressings and barrier creams
× Pain management and infection control
× No structural repair of the skin
× Lifelong dependency on palliative care
× No improvement in underlying fragility

→

The Mariposa Approach

Structural rescue

✓ Activates compensatory keratin expression
✓ Restores functional intermediate filaments
✓ Prevents blistering at the cellular level
✓ Works across EBS subtypes
✓ Potential to restore normal mobility and life

Our Science

We don't repair the broken keratin. We give the skin a second one.

MP5219 is a novel small molecule that activates the expression of Keratin 17 and other inducible keratins. These induced keratins compensate for the damaged K5/K14, forming alternative functional intermediate filaments that protect skin from mechanical and heat stress-induced blistering.

Confocal microscopy: Healthy keratinocytes with intact filament network

Healthy Cells

Intact, organised keratin intermediate filament network

EBS Disease Model

Collapsed filaments clustered around the nucleus

MP5219 Treated

Rescued intermediate filament network

Confocal microscopy of keratinocytes immunostained for keratin intermediate filaments (green) with DAPI-stained nuclei (blue). Mariposa Therapeutics laboratory data.

Proven skin penetration

Successfully penetrates ex vivo human skin to reliably elevate compensatory K17 expression in the targeted basal layer.

Clean safety profile

No safety concerns in in vitro testing: off-target effects, genotoxicity, and cardiac inhibition all negative.

A platform with broader potential

The keratin modulation platform underpinning MP5219 has potential applications beyond EBS, opening pathways to other conditions where keratin dysfunction drives disease.

Our Focus

MP5219: a topical cream for EB Simplex.

The lead programme

MP5219-1 is being developed as a simple topical cream — applied directly to the skin — designed to activate compensatory keratins and restore the structural integrity that EBS patients lack from birth.

The goal is a treatment that patients can use at home, as part of their daily routine, to meaningfully reduce blistering and improve quality of life. For a community that has never had a disease-modifying option, this would represent a fundamental change.

Completed

Drug discovery, lead optimisation, safety and efficacy studies

Current

Formulation development, manufacturing scale-up, regulatory preparation

First-in-human clinical study in EB Simplex patients

The keratin modulation platform underpinning MP5219 has potential applications in other keratin-related conditions, representing a broader opportunity for the science.

Our People

The team bringing this to patients.

Leadership

Dr David Howat

Chief Executive Officer

36 years' pharmaceutical experience in small and mid-sized biotech. Multiple products into Phase I, II & III. Exits including licence, trade sale and IPO.

Dr Lucy Sykes

Chief Scientific Officer

Award-winning cell and molecular biologist with deep expertise in drug discovery for genetic and epithelial disease. Industry, academic and public sector experience.

Andres Korin

Chief Financial Officer

20+ years in finance and investment banking (J.P. Morgan). CFO for multiple startups across healthtech and medical devices.

Board of Directors

Carin Beumer

Chair of the Board

30+ years in life sciences and 10 years in investment banking. Board leadership of global NGOs and educational institutions. INSEAD-certified director.

Thomas Hafner

Founder & Executive Director

30+ years building life science companies from concept to successful exits, up to nine figures.

Dr Bill Pigg

Non-Executive Director

30+ years at Smith & Nephew, J&J, and Acelity/KCI. Former VP of R&D and Regulatory Affairs. Deep regulatory and commercial expertise.

Damian Marron

Non-Executive Director

Serial CEO and board director with decades of biotech expertise. Chair of Circio Holdings and Nicox SA. Multiple nine-figure exits.

Scientific & Clinical Advisors

Prof Adrian Heagarty

Consultant Dermatologist; Head of the half-national EB Service, University Hospitals Birmingham. Member of DEBRA International Medical & Scientific Advisory Panel.

Dr Phil Dudfield

Former Managing Director of Fidelta (Galapagos Group). 30+ years in drug discovery and development with a proven delivery track record.

Dr Robyn Hickerson

PI at University of Dundee. Co-founder & CSO, TenBio. Expert in rare genetic skin disorders and novel ex vivo human skin models.

Our Partners & Supporters

Backed by those closest to the disease.

Mariposa's development has been supported from the earliest stages by the organisations and individuals most deeply committed to finding treatments for EB.

Investors

Development Bank of WalesThe Welsh Government's development finance arm, supporting innovation-led businesses across Wales.
EB Research PartnershipOne of the world's leading charities dedicated to funding EB research. A core investor in Mariposa across multiple rounds.
DEBRA Research GmbHA world-leading EB charity and core investor, following rigorous independent evaluation of the science.
Zaluvida VenturesA life sciences venture builder with 20+ years of experience incubating and scaling science-led companies from concept to global impact. Strategic partner providing capital, operational support, and co-creation.

Scientific & Clinical Partners

Cardiff UniversityDrug discovery and medicinal chemistry collaboration.
University of DundeeEx vivo skin model development and efficacy testing.
University of HullFormulation science and topical drug delivery.
University Hospitals Birmingham NHS Foundation TrustClinical advisory and the half-national EB service.

News

Latest developments.

March 2025

Mariposa closes £750,000 pre-seed financing led by the Development Bank of Wales

Cardiff-based Mariposa Therapeutics has secured £750,000 in pre-seed financing led by the Development Bank of Wales, with participation from DEBRA Research GmbH, EB Research Partnership, and founding investors. The funding will advance MP5219 — the company's first-in-class small molecule designed to rescue keratin filament integrity in Epidermolysis Bullosa Simplex — through formulation development and regulatory preparation for first-in-human studies.

"This investment validates the potential of our approach to bring the first disease-modifying treatment to the EB Simplex community," said David Howat, CEO. "We are grateful for the confidence shown by our investors, particularly the EB charities whose rigorous scientific evaluation underpins this commitment."

A first medicine for EB Simplex is within reach.

Whether you are a patient, a researcher, a clinician, or an investor — if you believe in bringing healing to rare disease, we would like to hear from you.

Get in touch → Scientific partnerships →