OBJECTIVES: Neurofibromatosis type 1 (NF1), a rare autosomal dominant disorder, causes cutaneous neurofibromas (cNFs) that can appear all over the body. Although benign, CNFs can be associated with pain, anxiety and depression, and can interfere with physical, social and emotional functioning. To support development of a novel treatment of cNF, NFX-179 Topical Gel, NFlection wanted to understand what is most important to individuals in respect to the impact/bother associated with cNFs and explore the participant experience of meaningful change in cNFs within a Phase 2b trial.

METHODS: Concept elicitation interviews (N=10) were conducted to explore the lived experience of people with NF1 and to inform the development of two 7-point patient global impression of change (PGI-C) rating scales, capturing Overall cNF Change and Change in cNF Size, that were used in the trial. Qualitative exit interviews (N=40) were conducted with trial participants after treatment, discussing changes they experienced and how meaningful change was captured using the PGI-C scales.

RESULTS: Concept elicitation interviews showed that cNF size was the most salient aspect of cNFs and the driving factor in concerns about appearance. In the exit interviews, 62.5% (25/40) of participants reported improvement in at least 1 cNF after treatment with NFX-179 Topical Gel on either the PGI-C Overall or PGI-C Size scale. Flattening of the cNFs was the most commonly- reported change in this group (22/25; 88.0%). Of those experiencing an improvement, 80.0% (20/25) reported that a rating of “A little better/smaller” on the PGI-C scales represented the smallest level of meaningful change, regardless of cNF body location.

CONCLUSIONS: Size was shown to be the key aspect of cNFs, and changes in size, in particular height, are important to people living with NF1. The PGI-C scales captured this change, and a 1-category improvement was reported to reflect meaningful change on these scales.