CD33 (delivery antigen) / GSPT1 (degradation target)

Class

CD33-targeted antibody-drug conjugate delivering a GSPT1 molecular-glue degrader payload (antibody OR000283 + degrader payload SMol006, beta-glucuronide linker)

Pathway

Targeted protein degradation via the ubiquitin-proteasome system, delivered selectively to CD33-expressing cells

CD33 is a cell-surface protein expressed on myeloid lineage cells, including most acute myeloid leukemia (AML) blasts, making it a useful antigen for targeting drugs to these cells. This mechanism combines an antibody against CD33 with a payload that induces degradation of GSPT1, a protein required for normal translation termination during protein synthesis. Loss of GSPT1 disrupts this essential process and triggers cell death, an effect that is broadly toxic if delivered systemically. By attaching the GSPT1-degrading payload to a CD33-binding antibody through a cleavable linker, the degrader is concentrated in CD33-expressing cells after antibody binding and internalization, rather than circulating freely throughout the body. This antibody-drug conjugate (ADC) strategy is a rationale for pairing a broadly cytotoxic protein-degradation mechanism with a delivery system that restricts its activity, in principle improving the balance between killing malignant cells and sparing healthy tissue. This approach is relevant to AML and other myeloid malignancies, where CD33 expression is common on cancerous cells, and reflects a broader trend of using antibody-based targeting to make otherwise non-selective intracellular mechanisms, such as targeted protein degradation, into more tumor-directed therapies.