TLD-1433 Exhibits Early Efficacy in BCG-Unresponsive NMIBC CIS

Treatment with light-activated TLD-1433 (Ruvidar) displayed early efficacy among patients who have progressed following standard-of-care therapy for Bacillus Calmette-Guérin (BCG)–unresponsive non-muscle invasive bladder cancer (NMIBC) carcinoma in-situ (CIS) who are not candidates for radical cystectomy in a single-arm phase 2 trial (NCT03945162), according to a news release from the developer, Theralase.¹

Specifically, among 87 patients treated with TLD-1433 who were evaluable for efficacy, the complete response (CR) rate was 64.4% (n = 56; 95% CI, 48.6%-80.2%), with a total response rate of 73.6% (n = 64; 95% CI, 56.7%-90.5%). The total response rate includes those who experienced an indeterminate response (IR), defined as having a negative cystoscopy and positive or suspicious urine cytology.

Moreover, among 47 evaluable responders, 40.4% (n = 19; 95% CI, 23.8%-57.1%) experienced a sustained CR at 450 days, and 42.6% (n = 20; 95% CI, 26.6%-58.5%) experienced a sustained total response. Additional interim data revealed that the 2- and 3-year CR rates were both 21.3%, and 2.1% of patients sustained a CR after 7 years.

“Enrolling and treating 90 patients in our phase 2 registration clinical study represents a significant milestone for the company. With the targeted enrollment now completed, we can focus on compilation of the clinical data for Health Canada and FDA regulatory approval,” Roger DuMoulin-White, BSc, PEng, Pro Dir, president and chief executive officer of Theralase, said in a separate news release on the trial.² “2026 will be a pivotal year for the company as we complete our bladder cancer study, embark on a combinational clinical study for bladder cancer and launch numerous phase 1/2 adaptive clinical studies for brain, lung, muscle invasive bladder, pancreatic and colorectal cancers.”

Patients enrolled on the trial received a single intravesical instillation of TLD-1433 at 0.70 mg/cm² via bladder instillation and photodynamic therapy.³ After TLD-1433 was rinsed from the bladder, patients received subsequent photodynamic therapy with a separate TLC-3200 system.

The primary end point of the trial was CR rate. Secondary end points included 3-year CR and IR rates, as well as duration of response. An exploratory end point was safety.

Regarding safety, the developers noted that no serious adverse effects were likely attributable to study agents or devices. Moreover, they noted that the results of the trial exceed the International Bladder Cancer Group’s recommended guidelines for CR rates of 50% and 30% at 6 and 12 months, respectively, among CIS populations.

The trial completed enrollment and successfully treated 90 patients with TLD-1433 on February 2, 2026. Moreover, the developers plan to compile clinical data for a 2026 presentation to the FDA and Health Canada for an expected regulatory approval decision in 2027.

Those eligible for enrollment on the phase 2 trial were 18 years and older with histologically confirmed NMIBC CIS with or without resected Ta/T1 papillary disease who were not candidates for or refused radical cystectomy. Additionally, patients must have had an ECOG performance status of 0 to 2 and the ability to retain study drugs for a minimum of 60 minutes to have enrolled on the trial.

Exclusion criteria included those who experienced past or current muscle invasion, had concurrent extravesical non-muscle invasive transitional cell carcinoma of the urothelium, or active gross hematuria. Additionally, those receiving treatment with a prohibited concomitant therapy, those with an additional malignancy requiring treatment for progression, or those who have contraindications to general or spinal anesthesia were ineligible to enroll on the study.

References

1. Theralase(R) provides update on bladder cancer clinical study. News release. Theralase. February 4, 2026. Accessed February 4, 2026. https://tinyurl.com/4dz8ca3m
2. Theralase(R) completes enrollment in bladder cancer clinical study. News release. Theralase. February 2, 2026. Accessed February 4, 2026. https://tinyurl.com/mr2ut6em
3. Intravesical photodynamic therapy ("PDT") in BCG-unresponsive/​intolerant non-muscle invasive bladder cancer ("NMIBC") patients. ClinicalTrials.gov. Updated November 24, 2025. Accessed February 4, 2026. https://tinyurl.com/4skudub6