CRISPR-Cas Systems as Synthetic Biology Platforms in Cancer Management: A Critical Appraisal of Programmable Tools, Engineered Circuits and Clinical Evidence

Abstract

Background: Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated (Cas) proteins are frequently described as a synthetic biology platform for oncology, yet the phrase conceals a wide range of very different engineering claims. Programmable nucleases, transcriptional regulators, base and prime editors, RNA-targeting effectors and sensing circuits differ substantially in maturity, and the evidence supporting each differs by orders of magnitude. Purpose and Scope: This critical narrative review evaluates whether the engineering promise attached to CRISPR-Cas systems in cancer management is matched by the strength of the underlying evidence. The review is organised around four engineering layers: molecular parts, sensing and actuating devices, cellular chassis, and the enclosing translational system of delivery, manufacture and governance. Coverage spans target discovery, tumour-selective circuit design, engineered immune-cell therapy, delivery, diagnostics and clinical translation. Approach: Peer-reviewed literature was identified through searching of biomedical and multidisciplinary bibliographic sources, supplemented by backward and forward citation searching, with priority given to primary experimental studies, clinical trial reports and methodologically substantial reviews. Principal Findings: Evidence strength declines sharply with increasing circuit complexity. Programmability at the level of molecular parts is well established, and multiplex-edited immune cells have produced reproducible remissions in refractory haematological malignancy across independent centres. By contrast, tumour-selective transcriptional logic circuits rest almost entirely on cell-line and xenograft data, with negligible independent replication and no clinical corroboration. Functional genomic screening is the most methodologically mature contribution of CRISPR-Cas to oncology, but conversion of dependencies into approved therapies remains rare. Delivery to solid tumours is the binding constraint, and the safety literature concerning on-target structural rearrangement, p53-mediated selection and pre-existing immunity remains unresolved at the scale and duration of follow-up currently available. Implications: The most defensible near-term applications are those that use CRISPR-Cas to simplify rather than complicate cellular products, and that relocate the delivery problem from tumour to immune compartment. Claims of tumour-selective genetic computation should be regarded as promising but preliminary.