Applicability of tumor spheroids for in vitro chemosensitivity assays

ABSTRACT

Introduction: Drug screening assays employing two-dimensional (2D) cultures of cancer cells have been largely replaced by three-dimensional (3D) multicellular tumor spheroid (MCTS) models which more closely represent patient’s tumors. The predictive power of the different MCTSs depends on source of the cells, techniques of preparation, and characteristics of the aggregates.

Areas covered: The preparation of MCTSs and a comparison of the spheroids assembled from permanent cancer and patient-derived cell lines in respect to the correlation of their chemosensitivity to clinical responses are discussed. Spheroids formed in in vivo in pleural effusion and blood of cancer patients are presented as interesting sources for drug screening.

Expert opinion: 3D tumor models for drug screening were adopted to increase the predictive power of assays for success in clinical trials. Cell lines which form dense spheroids differ in physical properties, gene expression, and chemosensitivity from 2D cultures. Still, most of these MCTS models lack characteristics of complex tumor tissues and have not been validated for their adequacy to select clinically useful drugs. Patient-derived spheroids from pleural effusion or blood, namely tumorospheres of circulating tumor cells, are MCTS models most similar to patient’s tumors.

KEYWORDS:

• Drug screening
• tumor spheroid
• chemosensitivity
• ascites
• pleural effusion
• tumorospheres
• assay validation

Article highlights

• Tumor cell spheroids replace 2D cultures for drug screening

• Spheroid characteristics are dependent on specific formation

• Patient-derived spheroids are available from pleural effusion and blood

• Correlation of spheroid chemosensitivity and clinical responses

• Validation of spheroid assays using patient-derived tumor cells

• Spheroids of circulating tumor cells as relevant screening system

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.