Colorful depiction of immunogenic cell death (ICD) in cancer immunotherapy, featuring dying cancer cells releasing damage-associated molecular patterns (DAMPs) interacting with immune cells

Immunogenic cell death (ICD) is defined as a form of regulated cell death that triggers an immune response against the antigens of the dying cell.

This concept emerged from the observation that certain anticancer therapies can induce tumor cell death in a way that stimulates a protective antitumor immune response.

In contrast to non-immunogenic cell death, which may silently eliminate cells or even suppress immunity, ICD is characterized by the emission of specific damage-associated molecular patterns (DAMPs) that interact with pattern recognition receptors on immune cells to promote the uptake, processing, and presentation of tumor antigens.
The DAMPs include molecules like ATP, heat shock proteins, and calreticulin.

Mechanisms of Immunogenic Cell Death

The mechanism of ICD is shown in the following figure:

Diagram of the immunogenic cell death (ICD) process showing a dead tumor cell releasing damage-associated molecular patterns (DAMPs), followed by immune cell recruitment, phagocytosis, antigen presentation, and T-cell priming leading to an antitumor immune response

 

Mechanisms of Immunogenic Cell Death

The exact mechanisms of ICD vary depending on the trigger, but they generally involve two key steps:

  1. DAMP Release: Stressed or dying cells undergo changes in their surface molecules and release DAMPs into the extracellular environment.
  2. Antigen Presentation: Dendritic cells, the sentinels of the immune system, recognize DAMPs and engulf the dying cell fragments. These fragments are then processed and presented on the dendritic cell surface as major histocompatibility complex (MHC) molecules, which can be recognized by T cells, initiating a targeted immune response against the tumor.

Difference Between Immunogenic Cell Death (ICD) and Other Types of Cell Death

Immune ResponseImmunogenic Cell Death (ICD)Non-Immunogenic Cell Death
Release of Damage-Associated Molecular Patterns (DAMPs)Elicits an adaptive immune response against antigens of the dying cell, leading to immunological memory.Typically immunologically silent or even tolerogenic (e.g., apoptosis).
Antigenicity and AdjuvanticityProvides both antigenicity (tumor/pathogen antigens) and adjuvanticity (DAMPs) to stimulate an immune response.May lack one or both of these properties.
Regulated NatureInvolves the release of specific DAMPs like calreticulin, ATP, HMGB1 in a defined spatiotemporal manner.May not release these immunostimulatory DAMPs or release them differently.
Inflammatory PotentialA form of regulated cell death involving specific molecular pathways.Some types like accidental necrosis are uncontrolled.
Membrane IntegrityMaintains membrane integrity initially, eventually leads to membrane permeabilization.Necrosis disrupts membrane integrity early, while apoptosis maintains it.
Cellular Response RelevanceHighly inflammatory and immunostimulatory.Apoptosis is typically non-inflammatory; necrosis causes inflammation without adaptive immunity.
Therapeutic RelevanceICD inducers can enhance cancer immunotherapy responses.May not have immunotherapeutic potential.
Other Death Types May Not Require This Specific Stress ResponseOften involves endoplasmic reticulum stress.–

Key Molecular Hallmarks of Immunogenic Cell Death

  1. Calreticulin (CALR) exposure: CALR translocates from the endoplasmic reticulum to the cell surface, acting as an “eat me” signal for dendritic cells.
  2. ATP secretion: Dying cells release ATP, which acts as a chemoattractant for immune cells and activates the NLRP3 inflammasome.
  3. HMGB1 release: The nuclear protein HMGB1 is passively released and binds to TLR4 on dendritic cells to promote antigen processing and presentation.
  4. Type I interferon production: IFN-α/β signaling in cancer cells is crucial for optimal antitumor immunity following ICD.

Inducers of Immunogenic Cell Death

Various anticancer agents can induce ICD, including:

  1. Chemotherapy Drugs: Drugs like anthracyclines (e.g. doxorubicin), oxaliplatin, and cyclophosphamide can trigger ICD alongside their direct cytotoxic effects.
  2. Targeted Therapies: Certain tyrosine kinase inhibitors (e.g. crizotinib) and oncolytic viruses.
  3. Immunotherapy Drugs: Oncolytic viruses and certain immune checkpoint inhibitors, such as those targeting CTLA-4 and PD-1, can indirectly promote ICD.
  4. Physical Modalities: Radiotherapy, photodynamic therapy, and high hydrostatic pressure.
  5. Nanoparticle-Based Approaches: Immunogenic nanoparticles delivering chemotherapeutics or photosensitizers.
  6. Natural Compounds: Shikonin, hypericin, and wogonin.

Cell-Based & In Vitro Assays for Detecting Immunogenic Cell Death

Several assays can be used to assess ICD in vitro and in vivo. These assays measure various aspects of the process, including:

1. Detection of DAMPs

  • Calreticulin (CALR) Exposure: Measured using flow cytometry or immunofluorescence microscopy to detect surface-exposed CALR on dying cells.
  • ATP Release: Extracellular ATP can be quantified using bioluminescent assays such as the RealTime-Glo™ Extracellular ATP Assay.
  • HMGB1 Release: The release of HMGB1 can be detected using the Lumit™ HMGB1 Immunoassay.
  • Annexin A1 (ANXA1) and Type I Interferons: Measured using ELISA or other immunoassays.

2. Immune Cell Activation Assays

  • Phagocytosis Assays: Involving co-culturing antigen-presenting cells (APCs) with dying cells and measuring the uptake of the dying cells.
  • APC Maturation: Measured by staining markers like MHC class II, CD80, CD83, and CD86 using flow cytometry.
  • Cytokine Production: Measured using ELISA or intracellular staining followed by flow cytometry.

3. Functional Assays

  • Cross-Priming Assays: Co-culturing APCs with naïve T cells and measuring T cell proliferation.
  • Vaccination Assays: In vivo assays where mice are vaccinated with dying cells, and the immune response is measured.

Immunogenic Cell Death Induction – A Promising Cancer Immunotherapy Strategy

Following are the immunotherapeutic implications of ICD:

  1. Combining ICD inducers with immune checkpoint inhibitors to overcome resistance.
  2. Using ICD to convert immunologically “cold” tumors to “hot” tumors.
  3. Developing personalized cancer vaccines based on ICD.
  4. Exploiting ICD for CAR-T cell therapy of solid tumors.

Services Offered by MarinBio

Conclusion

Recent advances have greatly expanded our understanding of ICD mechanisms and its therapeutic potential. Harnessing ICD represents a promising approach to improve cancer immunotherapy outcomes. Further research is needed to optimize ICD induction strategies and develop predictive biomarkers of ICD to guide patient selection.

References

  1. Zhu, L., Wu, Y., Zhao, H. et al. Immunogenic cell death-related classification reveals prognosis and effectiveness of immunotherapy in breast cancer. Sci Rep 14, 2025 (2024). https://doi.org/10.1038/s41598-024-52353-4
  2. Kei-ichiro Arimoto, K-I., Miyauchi, S., Liu, M. Emerging role of immunogenic cell death in cancer immunotherapy. Front. Immunol. 2024. https://doi.org/10.3389/fimmu.2024.1390263
  3. Ahmed, A’, Tait, S.W.G. Targeting immunogenic cell death in cancer. Mol Oncol. 2020; 14:2994-3006. https://doi.org/10.1002/1878-0261.12851
  4. Fucikova, J., Kepp, O., Kasikova, L. et al. Detection of immunogenic cell death and its relevance for cancer therapy. Cell Death Dis 11, 1013 (2020). https://doi.org/10.1038/s41419-020-03221-2
  5. Mosar Corrêa Rodrigues, M.C., Morais, J.A.V., Ganassin, R. An Overview on Immunogenic Cell Death in Cancer Biology and Therapy. Pharmaceutics. 2022 Aug; 14:1564. https://doi.org/10.3390/pharmaceutics14081564
  6. Guo, W., Jia, L., Xie, L. et al. Turning anecdotal irradiation-induced anticancer immune responses into reproducible in situ cancer vaccines via disulfiram/copper-mediated enhanced immunogenic cell death of breast cancer cells. Cell Death Dis 15, 298 (2024). https://doi.org/10.1038/s41419-024-06644-3
  7. Luo, J., Luo, F., Li, Q. et al. An immunogenic cell death-related lncRNA signature correlates with prognosis and tumor immune microenvironment in bladder cancer. Sci Rep 14, 13106 (2024). https://doi.org/10.1038/s41598-024-63852-9
  8. De Silva, M., Tse, B.C.Y., Diakos, C.I. et al. Immunogenic cell death in colorectal cancer: a review of mechanisms and clinical utility. Cancer Immunol Immunother 73, 53 (2024). https://doi.org/10.1007/s00262-024-03641-5
  9. Ya-Ping, Li, Zhi-Ya Zhou, Liang Yan, Yi-Ping You, Hua-Yu Ke, Tao Yuan, Hai-Yan Yang, Rong Xu, Li-Hui Xu, Dong-Yun Ouyang, Qing-Bing Zha, Xian-Hui He, Inflammatory cell death PANoptosis is induced by the anti-cancer curaxin CBL0137 via eliciting the assembly of ZBP1-associated PANoptosome, Inflammation Research, 10.1007/s00011-024-01858-9, (2024).
  10. Han, Y., Tian, X., Zhai, J. Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot. Front. Cell Dev. Biol. 2024. https://doi.org/10.3389/fcell.2024.1363121
  11. Li, C., Wu, K., Yang, R. et al. Comprehensive analysis of immunogenic cell death-related gene and construction of prediction model based on WGCNA and multiple machine learning in severe COVID-19. Sci Rep 14, 8450 (2024). https://doi.org/10.1038/s41598-024-59117-0
  12. Amiri, M., Molavi, O., Sabetkam, S. et al. Stimulators of immunogenic cell death for cancer therapy: focusing on natural compounds. Cancer Cell Int 23, 200 (2023). https://doi.org/10.1186/s12935-023-03058-7
  13. Jiaqi Zhai, J., Gu, X., Liu, Y. Chemotherapeutic and targeted drugs-induced immunogenic cell death in cancer models and antitumor therapy: An update review. Front Pharmacol. 2023; 14: 1152934. https://doi.org/10.3389/fphar.2023.1152934
  14. Wang, J., Ma, J., Xie, F. Immunogenic cell death-based cancer vaccines: promising prospect in cancer therapy. Front. Immunol. 2024. https://doi.org/10.3389/fimmu.2024.1389173
  15. Zhang, J., Shi, X., Wang, M. et al. Identification of immunogenic cell death-related damage-related molecular patterns (DAMPs) to predict outcomes in patients with head and neck squamous cell carcinoma. J Cancer Res Clin Oncol 150, 240 (2024). https://doi.org/10.1007/s00432-024-05779-2