On January 7, 2026 Forlong Biotechnology, a clinical-stage biotech company focusing on developing transformative cytokine therapies for patients with severe unmet needs, reported that its Phase Ib/II study of FL115 (IL-15 Superagonist) in combination with anti-PD-1 antibody for patients with advanced solid tumor has been activated at the first clinical study site, Sun Yat-sen University Cancer Center; separately, its IND for FL115 Subcutaneous Injection has been accepted by Chinese NMPA.
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The Phase Ib/II study (NCT07131202) is an open-label, multicenter study to evaluate the safety, tolerability, preliminary efficacy, pharmacokinetics, and pharmacodynamics of FL115 in combination with an anti-PD-1 monoclonal antibody through IV infusion in patients with advanced solid tumors. The first clinical study site, Sun Yat-sen University Cancer Center, is now open and actively screening eligible participants.
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 monotherapy via IV infusion has been assessed in two Phase I studies in patients with advanced solid tumors, showing good safety profile with preliminary clinical efficacy (DCR 41% with PR 7%) supported by significant and sustainable expansion of NK and CD8+ T cells as well as strong transient induction of IFN-g. Clinical benefit have been observed in patients continuing on treatment, including 1 patient with Stable Disease over 68 weeks, and 2 patients with confirmed PR at 32 and 24 weeks respectively. Based on mechanism of action and literature, FL115 expects to be synergistic with anti-PD-1 antibody and the combination therapy expects to significantly enhance clinical efficacy especially for patients resistant or refractory to PD-1 therapy.
FL115, currently formulated at 20 mg/ml with stability over 3 years, especially fits for subcutaneous formulation development. Compared to IV infusion, FL115 subcutaneous injection has been shown to lower Cmax by over 20 fold while significantly increasing the meaningful exposure duration, with bioavailability at 60% or more. FL115 subcutaneous formulation expects to significantly enhance NK and T cell stimulation and clinical efficacy while improving safety profile by lowering release of certain cytokines. An abstract, "Development of FL-115, a novel IL-15 superagonist, as subcutaneous injection for cancer immunotherapy" has been accepted for presentation at the upcoming AACR (Free AACR Whitepaper) Annual Meeting 2026.
"FL115 monotherapy via IV infusion has demonstrated safety/tolerability with early signs of potent anti-tumor activity in Ph1 in patients with advanced solid tumors," said Dong Wei, Ph.D., Chief Executive Officer of Forlong Biotechnology, "FL115 in combination with anti-PD-1 antibody via IV infusion expects to significantly enhance clinical efficacy through synergy of mechanisms of actions while F115 subcutaneous formulation expects to further improve safety and efficacy profile as well as convenience. Such continuing clinical development activities will further establish FL115 as potential Best-in-class IL-15 superagonist, and bring new treatment options for cancer patients in need."
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. An IND of FL115 Subcutaneous Formulation has been accepted by Chinese NMPA.
(Press release, Forlong Biotechnology, JAN 7, 2026, View Source [SID1234661827])