Unlocking New Frontiers in Cancer Treatment: The NUS PTP1B Discovery

The National University of Singapore (NUS) has made a groundbreaking advancement in cancer immunotherapy with the identification of protein tyrosine phosphatase 1B (PTP1B) as a critical molecular switch that drives immunogenic cell death (ICD) in tumor cells. This discovery, detailed in a recent study published in the Journal of the American Chemical Society, reveals how specific platinum-based compounds can target PTP1B to enhance the body's immune response against cancer, particularly colorectal cancer.

Led by Professor Wee Han Ang from NUS's Department of Chemistry, the research team developed organoplatinum(II) compounds Pt-NHC and PlatinER (Pt-ER), classified as Type II ICD inducers. These agents not only kill cancer cells but also transform them into vaccines that alert the immune system, fostering long-term protection against tumor recurrence. In preclinical models, treated colorectal cancer cells conferred immunity, preventing tumor growth upon rechallenge.

This breakthrough addresses a key challenge in immunotherapy: many tumors evade immune detection. By flipping the PTP1B switch, NUS scientists have pinpointed a mechanism to make 'cold' tumors 'hot'—more visible and vulnerable to immune attack.

Cancer Burden in Singapore: Why This Matters Locally

Cancer remains Singapore's leading cause of death, with colorectal cancer ranking among the top three for both men and women. According to the Singapore Cancer Registry Annual Report 2023, released in early 2026, cancer mortality has declined 21% since 2012 despite rising incidence rates—attributed to early detection and treatment advances. Lifetime risk stands at 1 in 4 Singaporeans developing cancer by age 75, with colorectal cases showing increases in younger adults under 50.

The National Registry of Diseases Office notes lung, colorectal, and liver cancers drive most male deaths, while breast, colorectal, and lung affect females most. Five-year survival for localized colorectal cancer reaches 91%, but drops sharply for advanced stages, underscoring the need for immunotherapies like those targeting PTP1B.

Singapore's robust screening programs, such as the Screen for Life initiative, have boosted early detection, but immunotherapy innovations from NUS promise to elevate outcomes further, especially for metastatic cases.

Demystifying Immunogenic Cell Death: A Primer

Immunogenic cell death (ICD) is a form of regulated cell death where dying tumor cells release damage-associated molecular patterns (DAMPs)—like calreticulin (CRT), HMGB1, and ATP—that act as 'danger signals' to dendritic cells and T cells. This process turns tumors into endogenous vaccines, priming adaptive immunity for sustained anti-cancer effects.

Unlike classical apoptosis, ICD bridges innate and adaptive immunity. Key hallmarks include:

• Surface exposure of calreticulin (ecto-CRT), promoting phagocytosis.
• Release of HMGB1 and ATP, activating antigen-presenting cells.
• Endoplasmic reticulum (ER) stress via unfolded protein response (UPR) pathways like PERK.

Type I ICD inducers (e.g., anthracyclines) generate reactive oxygen species (ROS) in the cytosol; Type II (like NUS's Pt compounds) target ER stress. PTP1B inhibition disrupts ER homeostasis, amplifying these signals.

The Science Behind the NUS Breakthrough: Methods and Mechanisms

The NUS team employed cutting-edge proteomics to unmask PTP1B. Starting with Pt-ER, they engineered photoactivable probes (AfBPs) with diazirine/benzophenone groups for covalent tagging under UV light. These underwent photoaffinity labeling, click chemistry enrichment, and tandem mass tag (TMT) quantitative proteomics, pinpointing PTP1B among 515 enriched ER proteins.

Validation included:

1. Cellular thermal shift assays (CETSA): Pt-ER/Pt-NHC destabilized PTP1B (ΔTm -4.7°C/-5.5°C).
2. Enzymatic inhibition: IC50 ~20 μM.
3. Confocal colocalization: High Pearson's r (0.87-0.94).
4. siRNA knockdown/DPM-1001 inhibitor: Boosted ecto-CRT 1.42-1.45-fold, phagocytosis, PERK activation.

In vivo, Pt-ER vaccination yielded 60% tumor-free survival in CT26 colorectal models. Bioinformatics from TCGA/GTEx confirmed PTPN1 upregulation in colorectal adenocarcinoma, poor prognosis correlation, and ER stress gene links.

Funding from Singapore's Ministry of Education (A-8002492) supported this work.

Photo by Giovanni Crisalfi on Unsplash

PTP1B: From Metabolic Regulator to Cancer Target

PTP1B, encoded by PTPN1, dephosphorylates tyrosine residues, negatively regulating insulin/ leptin signaling. In cancer, it's overexpressed in colorectal, breast, and others, promoting progression while dampening T-cell activity—acting as an intracellular checkpoint.

The NUS study unveils its ICD role: PTP1B normally curbs PERK/eIF2α UPR arm; inhibition unleashes ER stress, CRT translocation, and phagocytosis. Prior work links PTP1B knockout to enhanced T-cell/CAR-T efficacy. Dual PTP1B/PTPN2 inhibitors like ABBV-CLS-484 are in Phase I trials globally, hinting at translational synergy.

Read the full NUS PTP1B study.

Spotlight on NUS Researchers Driving Innovation

Professor Wee Han Ang heads the Laboratory of Bioinorganic Chemistry at NUS, focusing on metal complexes for targeted cancer therapy. His team designs ICD inducers to overcome platinum resistance. Lead author Jiao Xia Zou, an NUS PhD candidate, spearheaded proteomics. Collaborator Assoc Prof Maria V. Babak (CityU HK) contributed drug discovery expertise.

"The current study revealed the link between PTP1B and the immune-stimulating effects of our platinum-based ICD inducers," says Prof Ang. "Next, we plan detailed structural studies of PlatinER-PTP1B interactions."

This exemplifies NUS's interdisciplinary strength. Aspiring researchers can explore research positions or higher ed jobs in Singapore's vibrant ecosystem.

Transforming Immunotherapy: Clinical Promise and Challenges

PTP1B targeting could synergize with PD-1 inhibitors, boosting 'cold' colorectal tumors' response rates (currently ~5% MSI-high). Preclinical data shows combo potential with TNFR2 blockers. While no Pt-ER trials yet, PTP1B inhibitors advance: ABBV-CLS series in Phase I for solid tumors.

Challenges: Specificity (PTP1B vs PTPN2), delivery, resistance. Singapore's S$50M precision oncology grants (SYMPHONY 2.0, Colo-SCRIPT) position NUS for trials.

NUS Cancer Science Institute and Duke-NUS partnerships accelerate translation. For career advice in oncology research, visit higher ed career advice.

Singapore's Thriving Cancer Research Landscape

Singapore invests heavily: NRF RIE2025 allocates billions to biotech; STCC-imCORE boosts immunotherapy. NUS hosts key hubs like CSI Singapore. Recent S$12M for histotripsy trials and PairX Bio spin-off highlight momentum.

• S$50M for precision oncology (2024).
• Declining mortality via screening/treatment.
• Global collaborations (e.g., Akoya Biosciences).

Universities like NUS drive Singapore university jobs in research.

Photo by Giovanni Crisalfi on Unsplash

Future Horizons: From Bench to Bedside

Near-term: Structural PTP1B-PlatinER studies, novel inhibitors. Long-term: Clinical trials for colorectal/gastric cancers, combos with CAR-T/PD-1. Bioinformatics suggests broad utility (breast, liver).

Stakeholders: Patients gain hope; researchers opportunities via university jobs; industry spin-offs. Prof Ang's vision: Precision chemoimmunotherapy.

Rate professors like Wee Han Ang on Rate My Professor.

Actionable Insights for Researchers and Patients

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