Forte Biosciences (NASDAQ:FBRX) shares jumped about 55% after the company reported positive phase 1b clinical trial results for FB102, an investigational therapy for vitiligo, showing statistically significant improvements in disease severity compared with placebo.
Vitiligo is a chronic autoimmune disorder where the immune system destroys melanocytes, the pigment-producing cells responsible for skin color, resulting in distinct white patches on the skin, hair, or mucous membranes.
The company reported that FB102-treated patients achieved a 29.6% mean improvement from baseline in the Facial Vitiligo Area Scoring Index (FVASI) at week 24, with the result reaching statistical significance.
Improvements were observed as early as day 64 and continued through week 24 after patients completed the 12-week treatment period.
Among patients with greater disease involvement at baseline, defined as FVASI scores of at least 0.75, FB102 produced a 43.2% mean FVASI improvement at week 24. Forte reported that 58.8% of patients in this group achieved FVASI50, while 23.5% achieved FVASI75.
Across the overall study population, 34.4% of FB102-treated patients achieved FVASI50 at week 24, while 12.5% reached FVASI75. The company noted that one placebo patient also achieved FVASI75, highlighting the importance of randomized controlled trials when evaluating responder rates in vitiligo.
Forte said most patients treated with FB102 continued to improve after the treatment period ended, with mean FVASI improvement increasing by an additional 8 percentage points between weeks 12 and 24. In patients with baseline FVASI scores of at least 0.75, improvement increased by an additional 14 percentage points over the same period.
The company reported that 84% of FB102-treated participants improved from baseline through week 24, with no patients worsening during the study period. By comparison, 27% of placebo-treated patients experienced worsening disease.
Forte also said FB102 maintained a favorable safety profile, with adverse events generally limited to mild to moderate severity and comparable to placebo.
The company is developing FB102 as an immune-modulating therapy designed to target CD122, a component involved in IL-2 and IL-15 signaling pathways. Forte said the mechanism is intended to reduce pathogenic T-cell activity while preserving regulatory T cells.
“With statistically significant placebo-controlled activity now demonstrated in vitiligo and the prior Phase 1b activity demonstrated in celiac disease, we look forward to the imminent readout from our ongoing Phase 2 celiac disease trial as the next important clinical catalyst for FB102,” Forte CEO Paul Wagner said in a statement.
“Data from this Phase 1b vitiligo study and from the previously reported Phase 1b trial in celiac disease reinforce the activity and broad potential for FB102.”