On August 4, 2026 Forlong Biotechnology, a clinical-stage biotech company focused on developing transformative cytokine therapies for patients with severe unmet needs, reported approval to initiate a Phase I study of FL115 subcutaneous injection (administered once every three weeks) in patients with advanced solid tumors in Australia. The study has been approved under Australia’s Therapeutic Goods Administration (TGA) Clinical Trial Notification (CTN) scheme, following review by the Human Research Ethics Committee (HREC).
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FL115, an engineered IL-15/IL-15Rα-Fbody fusion protein, has been evaluated as a monotherapy administered via IV infusion in two Phase I studies in patients with advanced solid tumors. These studies demonstrated a favorable safety profile along with preliminary clinical efficacy, supported by significant and sustained expansion of NK and CD8+ T cells, as well as a strong, transient induction of IFN-γ. Clinical benefit has been observed, with 3 patients remaining on treatment (one patient with stable disease and two patients with confirmed partial response) over 12 months.
Compared with IV infusion, subcutaneous administration of FL115 has been shown in preclinical studies to lower Cmax by more than 20-fold while significantly extending meaningful exposure duration, with bioavailability of 60% or higher and no significant gross skin irritation. Such a profile may enhance clinical efficacy through stronger NK and T cell stimulation, while also improving clinical safety by reducing the release of certain cytokines.
"FL115 monotherapy via IV infusion has demonstrated good safety and tolerability, with early signs of potent anti-tumor activity in Phase I studies in patients with heavily-pretreated solid tumors," said Dong Wei, Ph.D., Chief Executive Officer of Forlong Biotechnology. "We expect the subcutaneous formulation of FL115, dosed once every three weeks, to further improve the safety and efficacy profile, as well as convenience for patients — continuing to establish FL115 as a potential best-in-class IL-15 superagonist and, ultimately, bringing new treatment options to cancer patients in need."
About FL115
FL115 is an engineered IL-15/IL-15Rα-Fbody fusion protein designed to enhance anti-tumor immunity through IL-15-mediated signaling on NK and CD8+ T cells, while minimizing the complexity associated with an Fc domain. FL115 has demonstrated significant anti-tumor activity in vivo, both as a monotherapy and in combination therapy, and can be manufactured through a robust, efficient process with excellent product stability. Clinically, FL115 has shown a favorable safety profile and preliminary clinical responses as a monotherapy, and has best-in-class potential to synergize with current and emerging T cell–targeting immunotherapies through combination approaches that could meaningfully improve treatment outcomes for patients.
FL115 is currently being investigated in combination with Bacillus Calmette-Guérin (BCG) in a Phase II clinical trial evaluating safety and preliminary efficacy in patients with non-muscle invasive bladder cancer (NMIBC), and in combination with an anti-PD-1 monoclonal antibody in a Phase I clinical trial evaluating safety and preliminary efficacy in patients with advanced solid tumors. A Phase I clinical trial of FL115 subcutaneous injection is also being initiated in Australia.
(Press release, Forlong Biotechnology, AUG 4, 2026, View Source [SID1234669680])