Immunotherapy has revolutionized cancer treatment, providing a novel approach to combat this metastatic and heterogeneous disease.
Oncologists employ immunotherapeutic agents to enhance the body’s immune response to cancers, exploiting a previously untouched potential to fight cancer. However, not all patients respond to immunotherapy, and there is little known about the factors influencing the response.
Biomarkers and tumor pathology are determinants of immunotherapy response that can provide an insight into understanding this complex process.
What are Biomarkers?
Biomarkers are biological molecules found in blood, urine, or tissues and provide a means of assessing physiological, pathological, or pharmacological processes.
They have been crucial in the development of precision medicine, which seeks to personalize therapy and improve outcomes, thereby making a significant impact on the field of oncology. Biomarkers can be prognostic or predictive, and they can also serve as surrogate endpoints in clinical trials.
Biomarkers as Predictive Factors for Immunotherapy
Biomarkers serve as crucial predictive markers in determining which patients may benefit from immunotherapy. One of the most commonly used biomarkers is programmed cell death ligand 1 (PD-L1).
PD-L1 expression on the tumor cells or in the tumor microenvironment correlates with response to checkpoint inhibitor immunotherapy. Additionally, high tumor mutational burden (TMB) is another biomarker that has been correlated with response to checkpoint inhibitor immunotherapy.
TMB is calculated by measuring the number of somatic mutations per megabase of DNA, and tumors with a high TMB have been shown to be more susceptible to response to immunotherapy. Furthermore, the presence of specific genetic alterations, such as in the DNA mismatch repair system, has been correlated with response to checkpoint inhibitors.
Immune cell infiltration is also used as a predictive biomarker for response to immunotherapy. High levels of tumor-infiltrating lymphocytes (TILs) are associated with improved response to immunotherapy.
Tumor Pathology as Determinants of Immunotherapy Response
Tumor pathology, which captures the morphological and histological characteristics of the tumor, is another determinant of immunotherapy response.
The histologic analysis of the tumor can provide insights into the immune microenvironment, which is critical in determining response to immunotherapy. The presence of immune cells, such as TILs and myeloid-derived suppressor cells (MDSCs), can be assessed by histology. Furthermore, the composition of TILs can indicate response to immunotherapy.
High levels of CD8+ TILs have been shown to correlate with improved response to immunotherapy. On the other hand, tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) have been linked to resistance to immunotherapy.
Additionally, tumor histology, such as squamous versus non-squamous lung cancer, can also predict response to immunotherapy.
Clinical Implications and Future Directions
The identification of these biomarkers and tumor pathology as determinants of immunotherapy response has significant clinical implications.
The use of these biomarkers in clinical practice can help identify patients that are most likely to respond to immunotherapy, at the appropriate time and dose. Furthermore, the use of biomarkers in clinical trials can help design more efficient and successful trials, maximizing the benefits and minimizing the risks.
In the future, the development of new biomarkers and the incorporation of new tumor pathology characteristics can further enhance our understanding of immunotherapy response and improve patient outcomes.
Conclusion
Biomarkers and tumor pathology are determinants of immunotherapy response, providing crucial insights into the complex process of cancer immunotherapy.
As precision medicine continues to revolutionize oncology, the identification and validation of biomarkers and tumor pathology characteristics hold significant promise. The use of these markers in clinical practice and trials can improve patient outcomes and accelerate drug development.
