Phase 2 trial of IL-15 superagonist launches in NMIBC

The first patient has been dosed in a phase 2 trial of the investigational interleukin-15 (IL-15) superagonist FL115 in combination with BCG in patients with non-muscle invasive bladder cancer (NMIBC), Forlong Biotechnology announced in a news release.¹

“Dosing the first patient in our phase 2 trial for FL115 marks a defining moment for Forlong, as we advance our lead candidate further into clinical development and continue to validate the potential of our synthetic immunology platforms,” said Dong Wei, PhD, CEO of Forlong Biotechnology, in the news release.¹

The study will assess the combination of FL115 and BCG across 3 arms: patients with BCG-unresponsive NMIBC with carcinoma in situ (CIS), BCG-unresponsive high-risk papillary NMIBC, and BCG-naïve medium to high-risk NMIBC.

The open-label, phase 2 trial is enrolling participants across 12 clinical trial sites in China. Patients are eligible for enrollment in the study if they refuse or are not suitable for radical cystectomy and if have an ECOG performance score of 0 to 2, an expected survival of at least 2 years, and adequate organ function.²

The study will specifically assess complete response rate and duration of response in the CIS population and disease-free survival and relapse-free survival in patients with papillary disease. Final study completion is expected in October 2028.

The phase 2 study is aiming to build on data from the phase 1 portion of the trial, which assessed FL115 as a monotherapy. Overall, results from the study showed favorable safety and efficacy with the agent in patients with NMIBC. At the recommended dose for expansion, 4 of 6 patients achieved a response of at least 3 months, and 2 patients achieved a response for at least 9 months.

“FL115 stands out with favorable safety and preliminary efficacy observed in multiple phase 1 clinical studies in advanced solid tumors and NMIBC,” Wei added in the news release.¹ “With FL115 interim data for advanced solid tumor to be presented as Late Breaking Abstract on Nov 8 at the 40th Annual Meeting of the Society for Immunotherapy of Cancer (SITC 2025), this trial gives us the opportunity to further validate FL115 as potential Best-in-class IL-15 superagonist, and bring new treatment options for cancer patients in need.”

REFERENCES

1. Forlong dosed first patient in phase 2 clinical trial of FL115, a novel interleukin-15 (IL-15) superagonist, for nonmuscle invasive bladder cancer (NMIBC). News release. Forlong Biotechnology. October 30, 2025. Accessed November 3, 2025. https://www.businesswire.com/news/home/20251030585675/en/Forlong-Dosed-First-Patient-in-Phase-2-Clinical-Trial-of-FL115-a-novel-interleukin-15-IL-15-superagonist-for-nonmuscle-invasive-bladder-cancer-NMIBC

2. A study of intravesical FL115 alone or in combination with BCG in non-muscle invasive bladder cancer. ClinicalTrials.gov. Last updated August 14, 2025. Accessed November 3, 2025. https://clinicaltrials.gov/study/NCT07122414