LONDON – Treatment with the in an early clinical study.
In the ongoing phase 1/2 REFLECT (Recessive dystrophic EB: Mechanisms of fibrosis and its prevention with Losartan in vivo) trial, involving 29 children, no severe complications have been noted so far, according to one of the study investigators, Dimitra Kiritsi, MD, of the University of Freiburg, Germany. At the EB World Congress, organized by the Dystrophic Epidermolysis Bullosa Association (DEBRA), she presented interim data on 18 patients in the trial, emphasizing that the primary aim of the trial was to evaluate the safety of this treatment approach.
Over the 2 years the trial has been underway, 65 adverse events have been reported, of which 4 have been severe. Two of these were bacterial infections that required hospital treatment and the other two were a reduction in the general health condition of the child.
Losartan is an angiotensin-II receptor blocker (ARB) that has been in clinical use for more than 25 years in adults and 15 years in children over the age of 6 years.
The drug may be used for treating recessive dystrophic EB (RDEB) in the future, Dr. Kiritsi said, because it attenuates tumor necrosis factor–beta (TGF-beta) signaling, which is thought to be involved in the fibrotic process. So while it may not target the genetic defect, it could help ameliorate the effects of the disease.
The precursor to REFLECT was a study performed in a mouse disease model of EB (EMBO Mol Med. 2015;7:1211-28) where a reduction in fibrotic scarring was seen with losartan with “remarkable effects” on “mitten” deformity, Dr. Kiritsi said. The results of that study suggested that the earlier treatment with losartan was started in the course of the disease, the better the effect, she added. (Mitten deformity is the result of fused skin between the fingers or toes, and the subsequent buildup of fibrotic tissue causes the hand or foot to contract.)
REFLECT is an investigator-initiated trial that started in 2017 and is being funded by DEBRA International. It is a dual-center, nonrandomized, single-arm study in which children aged 3-16 years with RDEB are treated with losartan for 10 months, with follow-up at 3 months.
Various secondary endpoints were included to look for the first signs of any efficacy: the Physician’s Global Assessment (PGA), the Birmingham Epidermolysis Bullosa Severity Score (BEBS), the Epidermolysis Bullosa Disease Activity and Scarring Index (EBDASI), the Itch Assessment Scale for the Pediatric Burn Patients, and two quality of life indices: the Quality of Life in EB (QOLEB) questionnaire and the Children’s Dermatology Life Quality Index (CDLQI).
Dr. Kiritsi highlighted a few of the secondary endpoint findings, saying that reduced BEBS scores showed there was “amelioration of the patients’ phenotype” and that EBDASI scores also decreased, with “nearly 60% of the patients having significant improvement of their skin disease.” Importantly, itch improved in most of the patients, she said. Reductions in CDLQI were observed, “meaning that quality of life was significantly better at the end of the trial.” There were also decreases in inflammatory markers, such as C-reactive protein, interleukin-6, and TNF-alpha.
Although there is no validated tool available to assess hand function, Dr. Kiritsi and her team used their own morphometric scoring instrument to measure how far the hand could stretch; their evaluations suggested that this measure improved – or at least did not worsen – with losartan treatment, she noted.
A larger, randomized trial is needed to confirm if there is any benefit of losartan, but first, a new, easy-to-swallow losartan formulation needs to be developed specifically for EB in the pediatric population, Dr. Kiritsi said. Although a pediatric suspension of losartan was previously available, it is no longer on the market, so the next step is to develop a formulation that could be used in a pivotal clinical trial, she noted.
“Losartan faces fewer technical hurdles compared to other novel treatments as it is an established medicine,” Dr. Kiritsi and associates observed in a poster presentation. There are still economic hurdles, however, since “with losartan patents expired, companies cannot expect to recoup an investment into clinical studies” and alternative funding sources are needed.
In 2019, losartan was granted an orphan drug designation for the treatment of EB from both the Food and Drug Administration and the European Medicines Agency, but its use remains off label in children. “We decided to treat children,” Dr. Kiritsi said, “because we wanted to start as early as possible. If you already have mitten deformities, these cannot be reversed.”
DEBRA International funded the study. Dr. Kiritsi received research support from Rheacell GmbH and honoraria or consultation fees from Amryt Pharma and Rheacell GmbH. She has received other support from DEBRA International, EB Research Partnership, Fritz Thyssen Stiftung, German Research Foundation (funding of research projects), and 3R Pharma Consulting and Midas Pharma GmbH (consultation for losartan new drug formulation).
SOURCE: Kiritsi D et al. EB 2020. Poster 47.