German researchers have launched an innovative phase 2b multicenter basket trial to evaluate a single antifibrotic therapy across six rare fibrotic skin diseases that currently lack approved treatments. The study represents a novel approach to addressing the clinical research gap in conditions characterized by excessive extracellular matrix deposition, leading to tissue scarring and functional impairment.
The trial targets lichen sclerosus et atrophicus (LSA), frontal fibrosing alopecia (FFA), radiation-induced skin fibrosis (RISF), eosinophilic fasciitis (EF), pansclerotic disabling morphea (PDM), and linear circumscript sclerodermia (LCS). Despite their severity and debilitating nature, these diseases remain underrepresented in clinical research and lack approved therapies.
Innovative Trial Design Addresses Rare Disease Challenges
The study employs a two-stage Simon design specifically developed to address the statistical challenges posed by small patient populations. This approach allows inclusion of ultra-rare diseases while maintaining analytical rigor, a critical consideration given the limited patient pools available for these conditions.
LSA and FFA serve as primary study groups due to their higher prevalence compared to the other conditions. EF, RISF, PDM, and LCS are included as exploratory arms, enabling researchers to gather preliminary data on these even rarer conditions while focusing statistical power on the more prevalent diseases.
Primary and Secondary Outcome Measures
The trial's primary endpoint is a ≥21-point improvement in the Investigator Global Assessment (IGA) at 24 weeks. This standardized measure provides a consistent evaluation framework across the diverse disease presentations included in the study.
Secondary endpoints assessed at 52 weeks encompass multiple dimensions of patient outcomes, including quality of life measures using the Dermatology Life Quality Index (DLQI) and EQ-5D scales. The study also evaluates symptom relief through itch and pain numerical rating scales (NRS) and disease-specific clinical scores tailored to each condition.
Ethical Considerations Shape Study Design
The trial design excludes a placebo arm due to ethical considerations surrounding progressive, untreated diseases. Instead, the study allows rescue therapies for patients experiencing disease progression, balancing the need for scientific rigor with patient welfare considerations.
This approach facilitates access to treatment for underserved populations while leveraging shared clinical and molecular features across the fibrotic skin diseases to enhance statistical power. The study aims to assess efficacy, safety, and tolerability of the selected therapy, alongside mechanistic insights into fibrosis through molecular analyses.
Implications for Rare Disease Research
The basket trial design integrates disease-specific and global outcome measures to generate robust evidence for repurposing existing therapies. By targeting pathophysiologically related conditions with a single therapeutic approach, the study maximizes the potential for meaningful clinical insights despite the small patient populations typical of rare diseases.
If successful, this trial could serve as a model for future research in rare fibrotic diseases, potentially accelerating drug development and improving patient outcomes across multiple conditions simultaneously. The approach represents a paradigm shift from traditional single-disease trials toward more efficient, multi-condition studies that recognize shared pathophysiological mechanisms.
