South San Francisco-based TRexBio has filed an amended S-1 to raise approximately USD 116.7 million to USD 133.3 million in a Nasdaq IPO, offering 8.33 million shares at USD 14 to USD 16 each. The immunology company, which counts Lilly as a collaborator and investor, plans to trade under the symbol TRXB.
The company expects net proceeds of approximately USD 111.3 million at the midpoint, rising to USD 128.7 million if underwriters fully exercise their option to purchase additional shares. It will use the proceeds to fund Phase II trials of TRB-061 in atopic dermatitis and alopecia areata through topline results, and a Phase I trial of TRB-071 in inflammatory bowel disease.
Its lead wholly owned candidate, TRB-061, is a TNFR2 agonist Fc-fusion protein in Phase Ib testing for moderate-to-severe atopic dermatitis. TRexBio reported positive Phase Ia proof-of-mechanism results in healthy volunteers in August, with Phase Ib topline data expected in mid-2027. TRB-071, a CD30 agonist antibody, is in IND-enabling studies.
TRB-051 is covered by TRexBio’s 2023 agreement with Lilly, which granted the pharma exclusive worldwide rights to three immunology programmes for USD 55 million upfront, more than USD 1.1 billion in potential milestones and tiered royalties. Lilly funds clinical development and commercialisation and is also an equity investor in TRexBio. TRB-051 entered Phase I in 2024, with Lilly planning Phase IIa testing in lupus with cutaneous involvement in the second half of 2026.