The Dawn of a New Era in Cancer Therapy: A*STAR IMCB's Pan-TEAD Inhibitors

In the relentless battle against cancer, drug resistance remains one of the most formidable adversaries. Recent breakthroughs from Singapore's Agency for Science, Technology and Research (A*STAR) Institute of Molecular and Cell Biology (IMCB) are illuminating a promising path forward. Researchers have unveiled a novel class of pan-TEAD inhibitors designed to disrupt the YAP-TEAD interaction—a critical component of the Hippo signaling pathway implicated in tumor growth and therapy evasion. This discovery, detailed in a study published in ACS Medicinal Chemistry Letters, holds particular relevance for gastric cancers and non-small cell lung cancers (NSCLC) harboring KRAS or EGFR mutations, where resistance to targeted therapies is notoriously common.

Led by Professor Wanjin Hong, a distinguished scientist and Chief Business Development Officer at A*STAR's Biomedical Research Council, the team identified covalent small molecules featuring a vinyl sulfone warhead. These compounds bind irreversibly to a conserved cysteine residue on all four TEAD isoforms (TEAD1-4), effectively blocking their partnership with Yes-associated protein (YAP). This pan-TEAD approach ensures broad coverage, addressing the pathway's redundancy that has challenged previous selective inhibitors.

Unraveling the Hippo-YAP-TEAD Pathway: The Hidden Driver of Oncogenesis

The Hippo signaling pathway, first identified in Drosophila and conserved across mammals, acts as a master regulator of organ size, tissue homeostasis, and cell proliferation. Under normal conditions, it phosphorylates YAP and its paralog transcriptional co-activator with PDZ-binding motif (TAZ), sequestering them in the cytoplasm for degradation. However, in cancer cells, pathway dysregulation—often through upstream mutations or epigenetic changes—allows YAP/TAZ to translocate to the nucleus, where they bind TEAD transcription factors. This YAP/TAZ-TEAD complex then drives expression of pro-oncogenic genes like CTGF (connective tissue growth factor), CYR61, and AXL, fueling uncontrolled growth, metastasis, and survival.

In Singapore, where cancer is the leading cause of death, understanding this pathway is crucial. According to the National Cancer Centre Singapore (NCIS), over 91,000 cancer cases were diagnosed between 2019 and 2023, with lung cancer ranking as the top killer among men (26.4% of cancer deaths) and a significant burden for women (15.7%). Gastric cancer, though less common, affects around 500-600 new cases annually, often presenting at advanced stages with poor prognosis.

TEAD's role extends beyond initiation; it confers adaptive resistance. For instance, in EGFR-mutant NSCLC—prevalent in Asian populations at 40-60%—initial responses to tyrosine kinase inhibitors (TKIs) like osimertinib wane as YAP-TEAD upregulates survival pathways. Similarly, KRAS G12C inhibitors like sotorasib face bypass activation via YAP/TAZ-TEAD.

The Genesis of the Discovery: From Hypothesis to High-Throughput Screening

The IMCB team's journey began with recognizing TEAD's 'undruggable' reputation due to its lack of deep pockets for small molecules. Prior efforts focused on allosteric sites or palmitoylation inhibition, but covalent targeting of Cys380 (in TEAD2, conserved across isoforms) offered a breakthrough. Using structure-based design and high-throughput screening, they synthesized vinyl sulfone warhead-bearing molecules optimized for potency and selectivity.

Key compounds CPD10 and CPD13 emerged as standouts. CPD10 exhibits sub-micromolar IC50 values for disrupting YAP-TEAD binding, while CPD13 shows superior cellular activity. Both inhibit TEAD auto-palmitoylation—a post-translational modification essential for nuclear localization and stability—while uniquely preventing YAP docking, distinguishing them from existing inhibitors.

Potent Anticancer Activity in Preclinical Models

In vitro assays revealed profound effects. Gastric cancer cell lines like NCI-N87 and KATO-III, dependent on Hippo dysregulation, showed dose-dependent proliferation inhibition and reduced colony formation. NSCLC lines with KRAS G12C (H358) or EGFR mutants (PC-9, H1975) exhibited GI50 values in the low nanomolar range.

Crucially, monotherapy suppressed YAP-TEAD target genes (CTGF, CYR61), but combination with TKIs amplified synergy. In drug-resistant models—simulating acquired resistance via prolonged TKI exposure—CPD10/13 restored sensitivity, inducing apoptosis through synergistic downregulation of survival signals. This addresses a clinical pain point: over 50% of EGFR-mutant NSCLC patients develop resistance within 10-18 months.

Western blots confirmed reduced phospho-TEAD and YAP nuclear exclusion, with RNA-seq validating transcriptional shutdown of oncogenic programs.

Overcoming Resistance: A Synergistic Revolution

Drug resistance in KRAS/EGFR-driven cancers often stems from pathway reactivation. YAP-TEAD upregulation compensates for TKI blockade, sustaining AXL and CTGF-mediated survival. The IMCB inhibitors dismantle this 'bodyguard system,' as Prof Hong describes, by covalently locking TEAD in an inactive state. In co-culture models mimicking tumor microenvironments, combinations yielded Bliss synergy scores >10, far exceeding additive effects.

For Singapore, where NSCLC incidence rises (53,308 cases 1968-2021, 81.6% advanced stage), this could transform outcomes. EGFR mutations dominate locally, mirroring Asian trends, while KRAS variants pose parallel challenges.

Singapore's Research Powerhouse: A*STAR IMCB and Ecosystem Synergies

A*STAR IMCB, under Prof Hong's stewardship, exemplifies Singapore's biomedical prowess. With collaborations spanning NUS, NTU, and Experimental Drug Development Centre (EDDC), the institute translates discoveries rapidly. Prof Hong, a President's Science and Technology Medal recipient, has spawned 15 spin-offs, raising $30M+.

This study involved Bioinformatics Institute (BII) for computational modeling, underscoring interdisciplinary might. Singapore's RIE2025 invests S$25B in research, positioning it as Asia's biotech hub.

Global Context: TEAD Inhibitors in the Clinic

The IMCB work aligns with a burgeoning field. VT3989 (Viking Therapeutics) earned FDA Fast Track for mesothelioma (Hippo-altered), showing 40%+ disease control in Phase 1/2. IK-930 and others advance, though challenges like kidney toxicity persist. Pan-approaches like CPD10/13 may offer advantages over isoform-selective ones.

No TEAD inhibitors yet approved, but 2026 trials (NCT04665206, NCT06251310) signal momentum. IMCB's covalent vinyl sulfones could leapfrog via superior YAP disruption.

Implications for Patients and Future Directions

For gastric cancer patients (5-year survival ~30% advanced) and NSCLC (~20%), these inhibitors promise extended progression-free survival via combinations. In Singapore, with declining mortality (21% drop since 2012 despite rising cases), such innovations amplify gains.

Next: in vivo xenograft validation, AI-optimized leads (Boltz-2), IND-enabling studies. Prof Hong notes: "Our work opens new possibilities for combination therapies." Dr Kumar adds distinction in dual palmitoylation/YAP block.

Charting the Path Forward in Singapore's War on Cancer

Singapore's National Precision Medicine program and Cancer Control Plan 2030 integrate such advances. A*STAR's ecosystem fosters academia-industry bridges, vital for clinical translation. As KRAS G12C inhibitors like adagrasib gain traction, TEAD combos could redefine standards.

Challenges remain: optimizing pharmacokinetics, mitigating off-targets, clinical biomarkers. Yet, this IMCB milestone underscores Singapore's role in global oncology, blending rigorous science with real-world impact.

Photo by National Institute of Allergy and Infectious Diseases on Unsplash

Stakeholder Perspectives: From Bench to Bedside

Oncologists hail the synergy potential; patients seek hope amid resistance. Bioethicists emphasize equitable access in multi-ethnic Singapore. Policymakers eye economic ripple—biotech jobs, spin-offs.

• Enhanced TKI durability: Potential 2x PFS extension.
• Biomarker-driven: Hippo scores for patient selection.
• Combo safety: Preliminary low toxicity in cells.