Forlong Biotechology to Present Preclinical Data from FL115, a novel interleukin-15 (IL-15) superagonist, and FL116, a PD-1/interleukin-18 (IL-18) bispecific antibody, at the 2026 AACR Annual Meeting

SHANGHAI & SUZHOU, China--(BUSINESS WIRE)--Forlong Biotechnology, a clinical-stage biotech company focusing on developing transformative cytokine therapies for patients with severe unmet needs, today announced that preclinical data from its IL-15 and IL-18 programs will be presented at the 2026 AACR Annual Meeting held April 17-22, 2026 in San Diego, California.

IL-15 Programs: FL115 is an engineered IL-15/IL15Rα-Fbody fusion protein and has demonstrated best-in-class (BIC) profile as monotherapy in heavily pre-treated patients with late stage solid tumors, of which 3 patients (~10%) remain on treatment and progression-free currently at 9, 11 and 20 months respectively. Poster 7932 further elucidated mechanism of action underlying FL115 BIC profile, with Cryo-EM analysis of FL115/FcRn/β2M complex. In vivo, RNA-Seq and single-cell transcriptomics revealed FL115 reshaped the tumor microenvironment by enhancing NK and T cells infiltration without not triggering activation of neutrophils and macrophage. Poster 6459 showed significant potential of FL115 subcutaneous formulation. Compared to IV injection, subcutaneous injection of FL115 resulted in drastic lowering of Cmax (up to 26.7×) with bioavailability at ~60% as well as good linearity in PK file. FL115 at approximately 9 mg per injection site in rabbits showed no significant gross skin irritation.

IL-18 Programs: using structural modeling with our AI-driven Intelligent Biomolecular Discovery Platform, we developed a series of engineered IL-18 variants (IL-18v) that fully escape IL-18BP neutralization while providing tunable IL-18R1 affinity, enabling customizable cytokine potency, as described in Poster 7779. Based on one such IL-18v, we developed FL116, a PD-1/interleukin-18 (IL-18) bispecific antibody.
Poster 1777 showed FL116 achieved potent anti-tumor activities and rechallenge-confirmed immune memory while maintaining systemic immune homeostasis in multiple tumor models, and re-ignited intratumoral cytotoxic immunity while reshaping the TME toward a highly inflamed, effector-dominant state.

“Forlong’s pipeline strategy is to modulate the immune system with precision via stimulation of specific immune cell subpopulation through engineered cytokines, providing new options for patients,” said Dong Wei, Ph.D., Chief Executive Officer of Forlong Biotechnology, “IL-15 and IL-18 have long been believed to be attractive cytokines for cancer immunotherapy, and we appreciate the opportunity to present initial data of FL115 and FL116 programs to leading immuno-oncology experts in this prestigious forum.”

Poster Details:

Title: A tunable interleukin-18 (IL-18) platform engineered for complete escape from the decoy receptor IL-18 binding protein (IL-18BP)
Poster Number: 7779
Date & Time: 4/22/2026

Title: FL116, a PD-1/IL-18 bispecific antibody, enables cis-activation of PD-1⁺ T cells and reshapes the suppressive tumor microenvironment (TME)
Poster Number: 1777
Date & Time: 4/20/2026

Title: FL115, a novel IL-15 superagonist rationally designed to minimize safety risks for cancer immunotherapy
Poster Number: 7932
Date & Time: 4/22/2026

Title: Development of FL115, a novel IL-15 superagonist, as subcutaneous injection for cancer immunotherapy
Poster Number: 6459
Date & Time: 4/21/2026

About FL-115

FL115 is an engineered IL-15/IL15Rα-Fbody fusion protein, aiming to enhance anti-tumor immunity via IL-15-mediated signaling on NK and CD8+ T cells while minimizing complexity from Fc. FL115 has demonstrated significant anti-tumor activities as a monotherapy or as part of combination therapy in vivo, and can be manufactured by a robust and efficient process with excellent product stability. Clinically, FL115 has demonstrated favorable safety profile and preliminary clinical responses as a monotherapy, and has the best-in-class potential to synergize with current and emerging T cell-targeting immunotherapies through combination therapy to significantly improve the treatment outcome for patients. It is currently being investigated in combination with Bacillus Calmette-Guérin (BCG) in a Phase 2 clinical trial to evaluate safety and preliminary efficacy in patients with nonmuscle invasive bladder cancer (NMIBC) and in combination with an anti-PD1 monoclonal antibody in a Phase 1b/2 clinical trial to evaluate safety and preliminary efficacy in patients with advanced solid tumors.

About Forlong Biotechnology

Forlong Biotechnology is a clinical-stage biotech company focusing on developing transformative cytokine therapies for cancer patients with severe unmet needs. It has established four proprietary synthetic immunology platforms: Fbody ® Long-acting Technology Platform, Fc engineering platform, Syntokine® Synthetic Cytokine Platform and AI-driven Intelligent Biomolecular Discovery Platform. The leading candidate FL115 is interleukin-15 (IL-15) superagonist with best-in-class potential, currently being advanced to combo therapy with PD-(L)1 antibodies in Phase I for patients with solid tumors and combo therapy with BCG in Phase II for patients with NMIBC. Its second candidate FL116 is a PD-1 antibody fused with interleukin-18 (IL-18) mutein which is engineered to bind IL-18 receptor and not IL-18BP (a decoy), and has demonstrated potent tumor-killing efficacy in multiple in vivo tumor models resistant to immune checkpoint inhibitors.