Medium-term Follow-up of Vascular-targeted Photodynamic Therapy of Localized Prostate Cancer Using TOOKAD Soluble WST-11 (Phase II Trials)

Abstract

Background and objective: To assess the medium-term tumor control in patients with localized prostate cancer (PCa) treated with vascular-targeted photodynamic (VTP) therapy with TOOKAD Soluble WST11 (VTP) and to assess the medium-term tolerability of the treatment.

Design, setting, participants, and intervention: During the clinical phase II studies, 68 patients were treated with VTP under optimal treatment conditions (WST11 at 4mg/kg, light energy at 200J/cm, and a light density index ≥1) and have been included in a 3.5-yr follow-up.

Outcome measurements and statistical analysis: Post-interventional visits were scheduled every 6 mo and conducted as per local standard practice in each study center. Cancer-free status was assessed by means of prostate-specific antigen kinetics, multiparametric magnetic resonance imaging and/or prostate biopsies.

Results and limitations: At the end of the 3.5-yr follow-up, overall successful focal ablation was achieved for 51 patients (75%). Cancer was identified in the untreated lobe in 17 patients (25%). In total, 34 patients (50%) were cancer-free in both the prostate lobes. In case of recurrent/persistent malignancy, the Gleason score remained consistent or changed at the maximum by one point (upgrading by 1 Gleason point to 3+4 for eight patients and 4+3 for two patients). There were 64 related adverse events (AEs): 48% were Clavien grade I, 47% were grade II, and 5% were grade III. There were no Clavien grade IV and V AEs. Limitations included small sample size and heterogeneity in the follow-up for some centers.

Conclusions: VTP is a safe and efficient treatment and represents an alternative option for localized low-risk PCa management over the medium term. Precise diagnostic methods and imaging tools are thereby essential requirements to ensure safe and complete targeted therapy.

Patient summary: In this report, we looked at the medium-term outcomes of focal photodynamic therapy for early-stage prostate cancer. We found that this form of treatment is efficient and might have the potential to become a therapeutic option for low-risk cancer. Effectiveness depends on precise diagnostic methods, such as magnetic resonance imaging and accurate biopsy.

Keywords: Focal therapy; Medium term follow-up; Padeliporfin; Prostate carcinoma; TOOKAD; Vascular-targeted therapy.