LAN-1

Laser Power and PBNP Concentration Controls PBNP-PTT Thermal Dose

Photothermal therapy (PTT) is successful for tumor ablation and has been applied in conjunction with immunotherapy; however, the immunogenic outcome of PTT is unclear. Sekhri et al.delivered defined thermal doses using Prussian-blue-nanoparticle PBNP-PTT to SH-SY5Y and LAN-1 neuroblastoma cells. ICD markers, costimulatory/immune-checkpoint molecules, MHC, NK ligands, and T-cell cytotoxicity were measured. Determine dose-dependent immunogenicity profiles to predict PTT efficacy for neuroblastoma immunotherapy.

PBNP-PTT dosing was adjusted in vitro by altering the PBNP concentration and near-infrared laser power. They synthesized PBNPs with a mean diameter of 55 nm and a surface charge of −39 mV. SH-SY5Y and LAN-1 cells were exposed to PBNP-PTT under varying conditions. The temperature increase during the heating phase was higher at greater laser power in SH-SY5Y cells (Fig. 1A). These temperature profiles were converted to cumulative equivalent minutes at 43 °C (∑CEM43) to determine that thermal dose is dependent on both PBNP concentration and laser power (Fig. 1B). Increasing the thermal dose decreased SH-SY5Y cell viability. We observed 96% killing of SH-SY5Y cells at a thermal dose of 11.3 log(∑CEM43). A similar trend was observed in LAN-1 cells, with increasing temperature, thermal dose, and PBNP concentration leading to decreasing cell viability. We achieved 98% killing of LAN-1 cells at 11.3 log(∑CEM43) (Fig. 1D and E).

Fig. 1. PBNP-PTT-administered thermal dose is controlled by PBNP concentration and laser power (Sekhri P, Ledezma DK, et al., 2022).

CDKi Treatment Triggers NB Cell Differentiation and Impairs Viability

Neuroblastoma (NB) is not characterized by recurrent somatic mutations which limits therapeutic approaches. Inducing NB differentiation through differentiation therapy by agents such as cyclin dependent kinase inhibitors (CDKis) is emerging as a promising strategy. Retinoic acid (RA) is a known differentiation agent, but RA resistance is often observed. In this study, Shokraie et al. assessed 3 CDKis (abemaciclib, fadraciclib, dinaciclib) alone or in combination with RA, on NB cells to determine their ability to drive cell differentiation, growth, gene expression, and immunogenic cell death in MYCN amplified (LAN-1, CHLA-90) and non-amplified (CHLA-172) cell lines.

NB cell lines (LAN-1, CHLA-90, and CHLA-172) were exposed to increasing doses of CDKi and cell metabolic activity was determined at 72h and 2×72h time points (Fig. 2). Exposure to low doses of abemaciclib (0.1µM) was sufficient to drive stromal-like morphology (flattened cytoplasm and enhanced cell to cell adhesion) indicative of glial differentiation and higher cytotoxicity for dinaciclib/fadraciclib (Fig. 2A). Dose response curves for these CDKis confirmed these results and 2×72h exposures amplified the effects (Fig. 2B). Chromosome 12 polysomy (CDK4 amplification) was observed in all three cell lines. Partial deletion of CDKN2A was observed in LAN-1 and CHLA-172 lines, while amplification of CHKN2A was observed in CHLA-90 (Fig. 2C).

Fig. 2. Dose response curve and molecular analysis (Shokraie F, Lechermeier L, et al., 2025).