Apoptosis-Amplified Intracellular Paclitaxel Nanoparticle Formation Enhances Microtubule Aggregation and PANoptosis

The clinical efficacy of paclitaxel is limited by systemic toxicity at high doses and poor cellular uptake of nanoformulations. Intracellular paclitaxel nanostructure formation is a promising strategy, yet further enhancing its anticancer effect remains challenging. Herein, we propose a strategy of intracellular apoptosis-amplified paclitaxel nanoparticle formation by rationally designing a caspase-3-responsive peptide-paclitaxel conjugate Ac-Asp-Glu-Val-Asp-Cys(StBu)-Lys(paclitaxel)-CBT (Ac-DEVDC(StBu)K(PTX)-CBT). Upon intracellular glutathione reduction and caspase-3 cleavage, Ac-DEVDC(StBu)K(PTX)-CBT undergoes a CBT-Cys click reaction and subsequent self-assembly into paclitaxel nanoparticles. These nanoparticles aggregate microtubules and promote apoptosis, thereby activating more caspase-3 to drive further nanoparticle formation, creating an amplification loop for enhancing therapeutic outcome. In vitro, Ac-DEVDC(StBu)K(PTX)-CBT remarkably inhibited cell cycle, downregulated phosphorylated YAP-1 level by ∼48%, and induced ZBP-1/AIM2-based PANoptosis. Furthermore, in orthotopic tumor models, Ac-DEVDC(StBu)K(PTX)-CBT significantly increased caspase-3 expression compared to free paclitaxel treatment and markedly prolonged survival via cytoskeleton disruption. This strategy holds high promise for enhanced tumor treatment in the clinic.