PPM (PLZ4-targeted paclitaxel micelles) shows early complete remissions with clean safety in BCG-unresponsive NMIBC

PLZ4-coated paclitaxel-loaded micelles (PPM) are a solvent-free, intravesical nanoparticle designed to selectively bind bladder cancer cells (via the PLZ4 peptide) and deliver encapsulated paclitaxel for local cytotoxicity. In this first-in-human, single-arm Phase I dose-escalation study in BCG-unresponsive or BCG-intolerant NMIBC (NCT05519241), patients receive weekly intravesical PPM for 6 weeks at paclitaxel 25/50/75mg (0.5/1.0/1.5mg/mL); at the first dose level, 3 patients have been treated with no drug-related adverse events and 2/3 achieved complete remission at the 6-week post-treatment assessment. While efficacy is extremely preliminary, the early CR signal sits numerically above older intravesical salvage like valrubicin (CR 18–21% in BCG-failure CIS) and is directionally in the range of FDA-approved bladder-sparing options for BCG-unresponsive CIS such as pembrolizumab (41% CR at 3 months in KEYNOTE-057) and nadofaragene firadenovec (41% CR within 12 months; median DOR ~16 months), though those benchmarks come from much larger datasets and different assessment timepoints.