Interval- and cycle-dependent combined effect of STING agonist loaded lipid nanoparticles and a PD-1 antibody

Area of Science:

• Immunotherapy
• Nanomedicine
• Oncology

Background:

• Tumor resistance to Programmed Cell Death 1 (PD-1) blockade necessitates novel combination strategies.
• Stimulator of Interferon Genes (STING) pathway agonists are emerging as potent immune adjuvants.
• Combination immunotherapies aim to overcome treatment resistance and enhance antitumor activity.

Purpose of the Study:

• To investigate the optimal administration protocol for combining STING-LNP and PD-1 antibody therapy.
• To evaluate the impact of dosing interval, order, and cycles on antitumor efficacy against melanoma lung metastasis.
• To elucidate the immunological mechanisms underlying the combination therapy's effectiveness.

Main Methods:

• Utilized a melanoma lung metastasis model in mice.
• Administered combinations of STING-LNP and PD-1 antibody with varying protocols.
• Assessed antitumor activity and immune cell responses, including NK cell activation and gene expression (IFN-γ, PD-1, PD-L1).

Main Results:

• Single-cycle treatment showed no significant antitumor effect.
• Two and three cycles of combination therapy demonstrated a combined antitumor effect.
• Dosing interval and number of cycles significantly influenced the therapeutic outcome.
• The second and third doses increased gene expression of NK cell activation markers, IFN-γ, PD-1, and PD-L1.
• NK cells in the lung exhibited increased activation marker and PD-1 expression after the second dose.

Conclusions:

• The combined antitumor effect of STING-LNP and PD-1 antibody against melanoma lung metastasis is protocol-dependent.
• Optimizing the interval and number of cycles is crucial for maximizing therapeutic benefits.
• These findings highlight the importance of precise protocol design for nanoparticle-adjuvant and PD-1 antibody combinations.