Evaluation of PD-1 blockade using a multicellular tumor spheroid model

Area of Science:

• Oncology
• Immunotherapy
• Biomedical Engineering

Background:

• Three-dimensional multicellular tumor spheroids mimic solid tumor physiology.
• Existing in vitro models are insufficient for evaluating PD-1 blockade efficacy.
• PD-1 inhibitors are crucial in cancer immunotherapy.

Purpose of the Study:

• To establish and utilize tumor spheroids as an in vitro model for assessing PD-1 blockade cytotoxicity.
• To investigate the effects of PD-1 blockade on T-cell-mediated killing of gastric cancer spheroids.
• To explore the underlying mechanisms of PD-1 blockade in a spheroid model.

Main Methods:

• Generation of mature multicellular tumor spheroids from a human gastric cell line using ultra-low attachment microplates.
• Induction of PD-L1 expression on spheroids using interferon-gamma (IFN-γ) and tumor necrosis factor-alpha (TNF-α).
• Assessment of T-cell cytotoxicity against PD-L1-expressing spheroids following PD-1 blockade using confocal microscopy and mechanistic studies.

Main Results:

• PD-1 blockade significantly enhanced T-cell-mediated cytotoxicity against PD-L1-expressing gastric cancer spheroids.
• PD-1 blockade treatment led to increased expression of multiple chemokines within the spheroid microenvironment.
• The study successfully validated tumor spheroids as a functional in vitro model for PD-1 blockade evaluation.

Conclusions:

• Tumor spheroids serve as a valuable and novel platform for evaluating the efficacy of PD-1 blockade therapies.
• The findings support the potential use of this spheroid model for developing and optimizing future cancer combination therapies.
• This model provides insights into the immunomodulatory effects of PD-1 blockade, including chemokine modulation.