LONDON – Median survival among patients with generalized severe recessive dystrophic epidermolysis bullosa (RDEB-GS) after a first diagnosis of mucocutaneous squamous cell carcinoma (SCC) was 2.4 years in an observational, retrospective study.
The study, conducted at St. Thomas’ Hospital and Great Ormond Street Hospital in London, was a review of all individuals with EB who had developed the skin cancer over a 28-year period, from 1991 to 2019.
A total of 44 subjects were identified who together had 221 primary SCCs. Considering all study subjects, the median age at first diagnosis of SCC was 32.6 years, with a mean of five tumors present. Almost 40% had metastatic tumors, and of the 57% who died during the observation period, 88% of deaths were attributable to the SCC.
“EB-associated SCCs differ from those in the general population,” the study’s investigators wrote in a poster presented at the EB World Congress, organized by the Dystrophic Epidermolysis Bullosa Association (debra). “They affect a younger age group, and there are often multiple primaries,” they added. Furthermore, “they behave aggressively and metastasize early despite being well differentiated.”
Most (31) of the study participants had RDEB-GS and tended to develop their first SCC at a younger age than the group overall, at a median of 29.5 years (compared with 32.6 years for the overall group). The mean number of tumors was 5.8 among those with RDEB-GS, with over half (53.4%) of the SCCs being well differentiated and located on the hands, upper arms, feet, and lower legs. Median survival after a first diagnosis in this group was 2.4 years. The short survival after a first diagnosis of SCC “underscores the poor prognosis in this group,” the researchers wrote.
“As the largest cohort of EB SCC patients with comprehensive data regarding clinical course and management to date, our data reinforce the need for regular clinical surveillance for SCCs in EB patients,” the team concluded. This surveillance should start in adolescence for those with the severe generalized RDEB subtype, they advise, and from the third or fourth decade for other at-risk groups.
These data also highlight “the pressing need for more effective treatments,” the investigators wrote. Most (86.4%) of the SCCs among the patients in the study had been surgically removed by wide local excision, with a few patients undergoing lymph node dissection, radiotherapy, chemotherapy, electrochemotherapy, or receiving targeted cancer therapies such as erlotinib, cetuximab, or cemiplimab.
Surgery may not be an option for many patients,explained in an oral presentation at the meeting. Dr. Mellerio, a consultant dermatologist and chief of St John’s Institute of Dermatology at Guy’s & St. Thomas’ NHS Foundation, London, noted that the location of the tumor was important, as sometimes it was not physically possible to excise it completely.
Guidelines on how to manage SCCs in patients with EB were published a few years ago () and noted that the clinical detection of SCCs could be difficult because of chronic wound ulceration in these patients. The “possibility of malignancy should be borne in mind, with suspicious lesions biopsied for histological evaluation,” the document states. Evidence for many of the nonsurgical options – radiotherapy, conventional chemotherapy, biologic therapies – was poor, according to the guidelines, and effective nonsurgical options are still desperately needed.
Several avenues of research are being investigated, Dr. Mellerio noted, such as targeting the fibrotic process and perhaps using a micro-RNA inhibitor to stop the upregulation of certain microRNAs in fibroblasts. Targeting inflammatory mechanisms such as thrombospondin 1, which can lead to elevated levels of tumor necrosis factor–beta and contribute to extracellular matrix stiffness, also is under investigation. Raised interleukin-6 may be another target to consider.
Research shows that similar genes are mutated in EB-related and ultraviolet-related SCCs, Dr. Mellerio said. Indeed, mutations in HRAS, NOTCH1, TP53, and CDKN2A have been reported, but mutations in these genes occur much earlier in life in patients with EB. “Something else is going on,” she added, commenting that researchers are looking at apolipoprotein B editing complex (APOBEC) enzymes, which modulate DNA and can cause “particular types of genetic changes in EB cancers.”
One investigator who is studying the genetics of EB SCCs and how APOBEC enzymes might be involved is, an associate professor at Thomas Jefferson University, Philadelphia. APOBEC enzymes are a very prominent source of mutations in RDEB. These mutations are found in 10%-20% of squamous cell carcinomas not associated with RDEB, and 80%-90% of head and neck cancers, he said during a separate talk at the meeting.
Dr. South observed that “RDEB squamous cell carcinoma does not show any particular somatic mutation or upregulation or downregulation of genes that differentiates it from other squamous cell carcinomas, which might be disappointing on the front of it, but actually it does mean that precision therapies that have been developed for other squamous cell carcinomas have application in RDEB.”
RDEB SCC shows the greatest similarity with head and neck SCC, Dr. South said. He also stressed that fibrosis is a major driver of cancer development, SCC tumors in RDEB are homogenous, and that frontline therapy is still unclear.
What is clear, however, is that interdisciplinary management of patients is crucial, said, professor and chair of the department of dermatology at the University Medical Center, Albert Ludwig University of Freiburg, Germany.
“In severe RDEB, metastatic SCC is the leading cause of death at a young age. We need monitoring, careful diagnostics, and multidisciplinary treatment,” Dr. Bruckner-Tuderman said. The latter should be delivered by a coordinated team that consists of dermatologists, surgeons, radiologists, oncologists, pathologists, geneticists, and (molecular) tumor boards, she advised.
The study had no commercial funding. Dr. Mellerio disclosed financial relationships with Castle Creek Pharmaceuticals and ProQR Therapeutics, and acted as an unpaid advisor to Helpberby Therapeutics. Dr. South disclosed financial relationships with Krystal Biotech Inc. and Amryt Genetics and has been an advisory board member for Abeona Therapeutics and Sanofi Genzyme. Dr. Bruckner-Tuderman disclosed receiving grants or research support from Constant Pharmaceuticals/Tarix Orphan.