At the 2025 American Association for Cancer Research (AACR) Annual Meeting, Therapex presented for the first time its anti-CD33 ADC molecular glue TRX-214-1002, showing excellent GSPT1 degradation ability and anti-tumor activity against acute myeloid leukemia (AML), bringing new hope for clinical application of GSPT1-targeted drugs.
GSPT1, also known as eRF3a, is a key factor in the eukaryotic translation termination complex. It forms a complex with eRF1 to recognize stop codons and promote peptide chain release⁽¹⁾. In various tumors, elevated GSPT1 expression correlates with cell proliferation and drug resistance⁽²⁾, making it a potential target for novel anti-tumor drug development.
Biological Functions of GSPT1
- Translation Termination: GSPT1 binds to the ribosome and drives eRF1-catalyzed peptide hydrolysis.
- Cell Cycle Regulation: Participates in G1/S phase transition, affecting cell proliferation rate.
- Stress Response: Regulates endoplasmic reticulum stress and apoptosis signaling.
- G575N Mutation Background: The glycine at position 575 is mutated to aspartic acid; under Cereblon modulators such as CC-90009 or CC-885, GSPT1(G575N) is not ubiquitinated and degraded, highlighting this site as a critical interface for molecular glue-GSPT1 interaction.
- Mutation Functional Impact: GSPT1(G575N) retains functional binding to eRF1 and GTP hydrolysis activity but shows immune tolerance to E3 ubiquitin ligase recruitment induced by molecular glues, conferring selective drug resistance.
Relationship Between GSPT1 and Diseases
- Acute Myeloid Leukemia (AML): GSPT1 is highly expressed in AML cells and associated with poor prognosis.
- Solid Tumors: Multiple studies show that inhibiting GSPT1 induces DNA damage and apoptosis, increasing chemotherapy sensitivity.
- Application Value of G575N Mutation Model: Located in the critical GTPase domain at the C-terminus of GSPT1, this mutation blocks Cereblon-dependent molecular glue-induced ubiquitination and degradation of GSPT1 by agents like CC-90009, stabilizing the protein for at least 24 hours post-treatment. This model provides a reliable platform to evaluate resistance to second-generation degraders and optimize new molecular glues.
Current Research Landscape of GSPT1-Targeting Drugs
Using CRISPR/Cas9 technology, we knocked in the GSPT1-G575N point mutation into MV-4-11 cells, obtaining two stable clones (1B3, 2B1). In vitro pharmacodynamics validation showed that mutant cells exhibited increased IC₅₀ for the degrader SJ6986, indicating G575N mutation mediates drug resistance. This provides an important tool for subsequent optimization of targeted agents and resistance mechanism studies.
MV-4-11-GSPT1-G575N-KI Cells In Vitro Validation Data
MV-4-11 Cells In Vivo Validation Data
