Forte Biosciences’ FB102 showed significant facial repigmentation in Phase 1b vitiligo trial, with durable benefit post‑treatment and favorable safety profile.
Written By: Shaik Yasmeen, PharmD
Reviewed By: Pharmacally Editorial Team
Forte Biosciences has reported positive topline results from its randomized, double-blind, placebo-controlled Phase 1b trial (NCT06905873) evaluating FB102 in patients with vitiligo, demonstrating statistically significant improvements in facial repigmentation and sustained clinical benefit through Week 24. The findings suggest that treatment effects continued for 12 weeks after completion of the 12-week dosing period, supporting the drug’s proposed immune-modulating mechanism.
FB102 achieved a 29.6% mean improvement from baseline in Facial Vitiligo Area Scoring Index (FVASI) at Week 24 compared with placebo in the protocol-defined efficacy-evaluable population (p=0.020). Clinical improvement became statistically significant by Day 64 (p=0.023) and continued to increase through the end of follow-up.
Targeting pathogenic T cells while preserving immune regulation
FB102 is an investigational monoclonal antibody that blocks CD122, the shared beta subunit of the interleukin-2 (IL-2) and interleukin-15 (IL-15) receptors. By modulating signaling through both pathways while preserving regulatory T cells, the therapy aims to suppress pathogenic immune responses implicated in autoimmune diseases without broadly compromising immune regulation.
Vitiligo is a chronic autoimmune skin disorder in which immune cells destroy melanocytes, leading to progressive loss of skin pigmentation. Despite recent therapeutic advances, many patients continue to have limited treatment options capable of producing durable repigmentation.
Trial demonstrated sustained efficacy after treatment ended
The Phase 1b study enrolled 43 adults, randomized in a 3:1 ratio to receive FB102 (n=32) or placebo (n=11). The primary endpoint evaluated mean percentage improvement in FVASI from baseline using independent central review.
Among patients with more extensive facial disease (baseline FVASI ≥0.75), FB102 produced a 43.2% mean FVASI improvement at Week 24 versus placebo (p=0.006). In this subgroup, 58.8% of treated patients achieved FVASI50, while 23.5% reached FVASI75. Across the overall efficacy-evaluable population, 34.4% achieved FVASI50 and 12.5% achieved FVASI75.
Investigators also observed continued clinical improvement after dosing stopped. Patients receiving FB102 gained an additional 8 percentage-point improvement in mean FVASI between Weeks 12 and 24, while those with higher baseline disease severity experienced a further 14 percentage-point improvement during the same period.
Overall, 84% (27/32) of FB102-treated participants improved from baseline by Week 24, and none experienced disease worsening, compared with 27% (3/11) of placebo-treated participants whose disease progressed during follow-up.
The therapy was generally well tolerated. All reported adverse events were mild to moderate, and the safety profile remained comparable to placebo, consistent with earlier Phase 1b findings in celiac disease.
Clinical implications and Path Forward
Chairman and Chief Executive Officer Paul Wagner, PhD, said the vitiligo results, together with previously reported Phase 1b data in celiac disease, support FB102’s mechanism of modulating IL-2- and IL-15-dependent pathogenic T-cell activity while preserving regulatory T cells. He added that the company now looks ahead to the imminent Phase 2 readout in celiac disease, which represents the next major clinical milestone for the program.
The sustained efficacy observed after treatment completion suggests FB102 may induce durable immunologic effects rather than requiring continuous dosing. While these findings are encouraging, the study enrolled a relatively small number of participants, and larger, later-stage trials will be needed to confirm efficacy, safety, and long-term clinical benefit before regulatory advancement.
What this means for patients
The Phase 1b results indicate that FB102 may offer a new therapeutic approach for vitiligo by targeting immune pathways that drive pigment loss while preserving normal immune regulation. The continued improvement after treatment ended also raises the possibility of durable clinical benefit, although confirmation in larger clinical studies will be necessary before the therapy can become available to patients.
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About the Writer
Shaik Yasmeen (LinkedIn) is a Pharm.D graduate with interests in clinical pharmacy, pharmacovigilance, and medical writing. She has gained experience through hospital clinical postings, patient case reviews, case presentations, and literature evaluation. Passionate about evidence-based healthcare, she is committed to creating accurate and engaging medical content while continuously expanding her professional knowledge.