Immunohistochemistry Predictive Markers in Cancer Treatment

This report delves into the application of Immunohistochemistry (IHC) and the PD-L1 predictive marker in guiding therapeutic decisions for cancer treatment. The study highlights how IHC, utilizing antibodies to detect specific antigens, is pivotal in identifying cancer types and assessing the presence of cancer cells. The report specifically focuses on PD-L1, a protein overexpressed in cancer cells, and its role in inhibiting T-cell activity, thereby allowing tumor growth. The analysis covers the function of immune checkpoint inhibitors, which target PD-L1 to stimulate the immune system's response against cancer cells. It also discusses the FDA and EMA approvals of drugs targeting PD-L1 in treating various cancers, including malignant melanoma and non-small cell lung cancer, while acknowledging the limitations of PD-L1 assays, such as the lack of clear result interpretation boundaries. The report concludes by advocating for the integration of artificial intelligence algorithms with test data to enhance cancer diagnosis and therapy recommendations, thus improving treatment efficacy and patient outcomes.

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Title: Immunohistochemistry Predictive Markers (PD-L1) In Therapeutic Decisions.

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Oncologists for decades now have used predictive markers to clinically select suitable therapies
for treating malignancies. For many years, steroids receptor has been the preferred assessment of
these markers. However, it has been recently been overtaken by Immunohistochemistry.
Immunohistochemistry is a technique that uses antibodies to test the presence of specific
antigens in tissues. The antibodies are laced with a colorant or enzyme which is activated when
antibodies bind with antigens or markers (Hirsch, McElhinny, & Stanforth, 2017). Its major use
is to check for the presence of cancer and differentiate between different cancer types. There are
numerous IHC stains, among them is the PD-L1. PD-L1 is a protein expressed in some normal
cells but found in greater than normal amounts in cancer cells. PD-L1 binds onto a protein
known as PD-1 inhibiting T cells from destroying it. This serves the purpose of preventing T cell
vicious immune response destroying host tissues. However, in the case of cancer, it prevents T
cells from destroying cancer cells allowing an unchecked growth of tumors. Cancer drugs known
immune checkpoint inhibitors is bind to PD-L1 antibodies inhibiting them from binding to PD-1
antigen. This removes regulation of the immune allowing T cells to destroy cancer cells (Le,
Uram, Wang, & Med, 2015).

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Immunotherapy patient selection remains a challenging task due to a lack of highly specific and
sensitive biomarkers. However, a certain threshold has to be surpassed before tests are validated
to provide predictive information. PD-L1 one of the few established biomarkers assessments that
has established standard routine. One of the factors that have led to the PD-L1popularization is
because it functions as a selective biomarker. Not only does it indicate the presence of cancer,
but it also differentiates the type of cancer. There are different therapies recommendation
associated with specific results of PD-L1. Targeting PD-L1 as a predictive biomarker result in
reliable predictions. This can be attributed to its efficacy, ease in conducting the test and results
can be easily interpreted. Drugs targeting the PD-L1 have shown a success rate of 10-20% in
unselected and 30-45% for selected late-stage non-small cell lung cancer patients. The Food and

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Drug Administration (FDA) and the European Medical Agency (EMA) have issued several
approvals to such drugs in treating malignant melanoma (MM), non-small cell lung cancer
(NSCLC) among other types of cancer. These drugs produce a tolerable amount of toxins and are
relatively cheap (Marti, et al., 2014). However there PD-L1 assay faces its limitations. Test result
interpretation remains a grey area. There is a lack of clear borders in the results continuum thus
different recommendations may be made for the same result. Secondly, some patients that test
positive for IHC PD-L1 respond to consequent treatment (Tumeh, Harview, & Yearley, 2014).
This can be attributed to there may be other factors inhibiting immune response and PD-L1 are
also present in non-cancerous cells. The use of PD-L1 in therapeutic decisions has revolutionized
cancer identification and treatment. However, information from one test does suffice for
effective decision making. The use of artificial intelligence algorithms to analyze data from
different tests ought to be used for better cancer diagnosis and therapy recommendation.

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References
Hirsch, F., McElhinny, A., & Stanforth, D. (2017). PD-L1 Immunohistochemistry Assays for Lung Cancer:
Results from Phase 1 of the Blueprint PD-L1 IHC Assay Comparison Project. J Thorac Oncol .
Le, D., Uram, J., Wang, H., & Med, N. E. (2015). PD-1 Blockade in Tumors with Mismatch-Repair
Deficiency. Med, N Engl J.
Marti, A., Martinez, P., Navarro, A., Cedres, S., MurtraGarrell, N., Salva, F., . . . Romero, L. (2014).
Concordance of PD-L1 expression by different immunohistochemistry (IHC) definitions and in
situhybridization (ISH) in squamous cell carcinoma (SCC) of the lung.. J Clin Oncol, 32.
Tumeh, P., Harview, C., & Yearley, J. ( 2014). PD-1 blockade induces responses by inhibiting adaptive
immune resistance. Nature.