Companion Diagnostics, Precision Medicine and Immuno- Oncology Therapies

by Lucas Barone

A Brief History and Background of Immuno-Oncology Therapy

Wilhelm Busch, a German surgeon, made an important observation in 1868 that ushered in the era of what we now call immuno-oncology. At that time, he noted a curious regression of a patient’s tumor size following an experimental infection of the patient with bacteria.  Influenced by several other experiments inducing immune stimulation to treat cancer in America and Europe, the concept of antibodies as cancer therapy was proposed by Paul Ehrlich, another German physician.1,2 Over the next century, the momentum in immunology continued to drive the research that laid the groundwork for immuno-oncology as we know it today.

In the middle of the twentieth century, researchers scored a series of triumphs with the discovery of the natural selection theory of antibody formation, interferon signaling proteins, the chemical structure of antibodies, the cancer immunosurveillance theory, the first cancer vaccine study, and the thymus producing T cells. Following in the successful footsteps of the 1950s and 60s, immuno-oncology-related innovation experienced an increased boom in the 1970s, with the discovery of the tumor necrosis factor (TNF) and the first description of natural killer (NK) cells.

“Clinical genomic profiling has increasingly shown that cancer is a heterogeneous disease that requires tailored treatment”

Furthermore, a molecular diagnostic tool was first used in the seventies to predict response to a breast cancer therapy. A high degree of correlation between  the  presence of the estrogen receptor and a positive treatment response was observed after treatment with the selective estrogen receptor modulator, tamoxifen. Subsequent clinical trials confirmed these observations,  and tamoxifen is now the standard of care for both pre-and postmenopausal women with early or advanced hormone receptor-positive breast tumors. Later, in 1998, the co-development of trastuzumab (Herceptin, Roche/Genentech) and the immunohistochemistry (IHC) assay, HercepTest (Dako/Agilent), demonstrated the value of the drug–diagnostic co-development model,3,4 spurring avenues of pharmaceutical and biotechnical collaboration and ushering a new era of personalized medicine.

The Era of Precision Medicine

Growing knowledge of the molecular underpinnings of the etiology of cancer has driven the field of precision medicine to identify specific tumor characteristics and exploit these features by developing targeted therapies against these tumors. The ability to predict an individual’s response to a specific therapy is the ultimate goal in modern precision medicine.5

Co-development of therapy- diagnostic pairs: Tools to characterize and  treat  tumors

Several targeted cancer therapies are currently utilized in standard oncological care as a result of the more detailed genetic and clinical understanding of individual tumor characteristics. The therapeutic use of molecular biomarkers with predictive clinical and pharmacological relevance relies on accurately detecting and/or quantifying these biomarkers to direct the safe and effective treatment of targeted therapies. As a result, the concept of drug– diagnostic co-development, or companion diagnostics, has emerged and is now the foundation of precision cancer medicine. According to the US Food and Drug Administration (FDA) guidance document for industry and FDA staff, “In-Vitro Companion Diagnostic Devices,” a companion diagnostic is defined as “an in vitro diagnostic device that provides information that is essential for the safe and effective use of a corresponding therapeutic product.”

These criteria are to:

  • identify those who would benefit from a therapeutic product,
  • identify those who are at increased risk of serious adverse reactions as a result of treatment with a therapeutic product,
  • identify patients for whom the therapeutic product has been adequately studied and found safe and effective, and
  • monitor response to a therapeutic product for the purpose of adjusting dose or treatment.

The FDA guidance document further stipulates that the use of a companion diagnostic with a therapeutic product must be included in the labeling instructions for both the therapeutic product and corresponding diagnostic test.

Though research in immuno-oncology has greatly advanced, traditional therapies such as surgery, chemotherapy, and radiotherapy are still widely applied. However, they can be harmful to the patient by affecting healthy tissues or only treating localized tumors without preventing underlying malignancies. The field of immuno-oncology, on the other hand, uses  a patient’s own immune system to target and eliminate tumors and malignancies, and reduce adverse events in the process. Furthermore, a companion diagnostics partnership creates tools that can predict outcome, thereby enhancing the efficacy and safety of a therapy targeted to patients who can receive the most benefit.

Clinical genomic profiling has increasingly shown that cancer is a heterogeneous disease that requires tailored treatment. Patients are being selected for specific chemotherapies and newer targeted therapeutics with greater confidence that their specific cancers will respond to treatment. Immuno-oncology approaches involving checkpoint inhibitors and other therapeutics in development are gaining acceptance and creating new demands and opportunities for companion diagnostics.

Herceptin

Due to its efficacy and wide use, Roche’s trastuzumab, marketed as Herceptin®, has become one of the best-known monoclonal antibody therapies. It was approved by the FDA in 1998, closely followed by approval  by the EMA in 2000. Trastuzumab is a recombinant humanized monoclonal antibody used for the treatment of HER2-positive early-stage or metastatic breast cancer, as well as HER2-positive metastatic adenocarcinoma. HER2 is a transmembrane receptor  protein that belongs to the family of receptor tyrosine kinases. In HER2-positive breast cancers, the HER2 protein is overexpressed, which causes an increase in intracellular signaling resulting in uncontrolled cell proliferation. Trastuzumab inhibits HER2 activity and flags the HER2- receptor so that the immune system can recognize and attack the tumor cells.6

In the same year, Herceptest was developed in a parallel project. It is a semi-quantitative immunohistochemical assay for determination of HER2 protein (oncoprotein c-erbB-2) overexpression in routinely processed breast cancer tissues for histological evaluation and embedded cancer tissue. HercepTest specifically demonstrates HER2 protein overexpression and is indicated as an aid in the evaluation of patients considered fit for Herceptin (trastuzumab) treatment.

The HER2 gene is a normal component present in two copies in all normal diploid cells. In a fraction of 15 to 20% of breast cancer patients, the HER2 gene is amplified as part of the process of malignant transformation and tumor progression. HER2 gene amplification leads to overexpression of HER2 protein on the surface of breast cancer cells, and its prevalence in conjunction with the presence of receptors correlate with poor breast cancer prognosis, including relapse-free and overall survival. HER2 IQFISH pharmDx is Agilent’s latest immunofluorescence diagnostic  kit  indicated as an aid in the evaluation of patients for whom Herceptin treatment is considered.

Avastin

In 2004, the FDA granted marketing approval  for Avastin® – also known as bevacizumab – for the treatment of a variety of cancers, including non-small-cell lung cancer, and breast, ovarian and colorectal neoplasms, as well as renal cell carcinoma. Bevacizumab is a recombinant humanized monoclonal antibody that can recognize and inhibit vascular endothelial growth factor (VEGF). The inhibition of VEGF slows down angiogenesis and reduces the growth of tumor blood vessels, which decreases the blood supply to the tumor and makes it more susceptible to chemotherapy.  Another well-known anti-tumor monoclonal antibody is cetuximab, marketed as Erbitux®. Cetuximab recognizes and attaches to epidermal growth factor receptor (EGFR) on tumor cells. Cetuximab inhibits EGFR and prevents it from activating RAS genes, which are responsible for tumor cell growth. Cetuximab was approved by the FDA and EMA in 2004, for the treatment of metastatic colorectal cancer and head and neck cancers.7

Antigen-presenting cells (APC) as targets

In active immuno-oncology, the patient’s own immune system is stimulated with the use of an antigen-presenting cells (APC). The immune system recognizes APCs as an invader and attacks them. Active therapies include cytokine treatments, therapeutic vaccines, immune checkpoint activators and inhibitors, and small molecules.

IL-2

Cytokine Treatments as small glycoproteins, cytokines bind to the surface receptors of immune cells and regulate their survival, development and function. Cytokine treatment is the oldest active immuno-oncology therapy and is based on the infusion of cytokines to activate the patient’s own immune system. IL-2, which is also used in the passive TIL therapy, was discovered as the T cell growth factor in 1976 and was approved by the FDA in 1992 for the treatment of metastatic renal cell carcinoma, and for metastatic melanoma in 1998. Though originally approved as a monotherapy, IL-2 is now being tested in combination with other cytokines like GM-CSF, cell-based immunotherapies, chemotherapeutic agents, peptide vaccines and immune checkpoint inhibitors. The only other FDA approved cytokine treatment to date is interferon-alpha (IFN-a), which activates NK cells, causing tumor cell death.8

“Precision medicine, companion diagnostics testing, and immune-oncology therapies in general will take on a much larger role in the future of cancer treatment”

Therapeutic Vaccines

The idea for the development of therapeutic vaccines came with the discovery that lymphocytes can selectively target antigens on tumor cell membranes and attack the tumor cells. Unlike traditional vaccines, therapeutic vaccines are not preventive, but have a therapeutic effect by strengthening a patient’s immune response. A variety of therapeutic vaccines is currently being studied. They are classified on the basis of the antigen they present and include dendritic cell vaccines, whole-cell tumor vaccines, DNA or RNA-based vaccines, protein or peptide vaccines, and viral based vaccines.9  To date, dendritic cell vaccines have been the most successful, as  the only therapeutic vaccine currently on the market is Dendreon Corporation’s sipuleucel-T (PROVENGE®), a dendritic cell vaccine that was approved by the FDA in 2010 and by the EMA in 2013 for the treatment of prostate cancer.10

In the body, dendritic cells are autologous antigen presenting cells (APCs) that present the antigens of incorporated foreign molecules on their surface membrane to T cells. To produce a dendritic cell vaccine, dendritic cells are isolated from the patient, genetically modified to express highly specific neoantigens, and then re-introduced into the patient where they activate T cells and result in tumor cell death.

PD1 and PD-L1

In order to prevent being attacked by the immune system’s T cells, other cells in the human body express co-receptors called immune checkpoints on their extracellular membrane. When a T cell binds to a checkpoint, it recognizes the cell as harmless and does not elicit an immune response. However, some cancer cells also express these same checkpoints, which allows them to go “unnoticed” by the body’s T cells and avoid an immune response.11

“When a drug blocks either PD1 or PD-L1, the T cell can then recognize the tumor cell, is activated and an immune response triggered, resulting in tumor cell death”

Agents that either activate or deactivate these immune checkpoints are very promising as cancer therapies. For instance, programmed cell death protein 1 (PD1) is an immune checkpoint receptor found on the surface of T-cells and B-cells. When PD1 binds to programmed death-ligand 1 (PD-L1) on the surface of other cells, it suppresses an immune response and the T cell remains deactivated. Unfortunately, many cancers also express PD-L1 on their surface so they remain unharmed by T cells.12,13

When a drug blocks either PD1 or PD-L1, the T cell can then recognize the tumor cell, is activated and an immune response triggered, resulting in tumor cell death. James P. Allison– discoverer of CTLA-4 – and Tasuku Honjo – discoverer of PD1 – received the Nobel Prize in Physiology or Medicine in 2018 for their work on immune checkpoint inhibitors.  In 2011, ipilimumab (YERVOY®) became the first immune checkpoint inhibitor to be approvednby the FDA. The active ingredient of YERVOY® is a monoclonal antibody that binds to and blocks the activity of cytotoxic T-lymphocyte- associated protein 4 (CTLA4), an immune checkpoint protein that is expressed on the surface of T cells. Binding by YERVOY®, activates T cells and triggers an immune response causing tumor cell lysis. YERVOY® is used for the treatment of advanced melanoma.14

The second immune checkpoint inhibitor to be marketed was nivolumab (Opdivo®), approved by the FDA in 2014 and the EMA in 2015. Nivolumab’s active component is a monoclonal antibody that binds to PD1, consequently preventing tumor cells from defeating T cells, which, in turn, increases immune response. This therapy can be used to treat melanoma, non-small cell lung cancer, advanced renal cell carcinoma, Hodgkin lymphoma, squamous cell cancer of the head and neck, and urothelial cancer.15

Other PD1 inhibitors include pembrolizumab (Keytruda®), approved by the FDA in 2014, Merck’s cancer drug Keytruda is expected to be the best-selling drug in the world by 2023, according to a report from the research firm GlobalData. It projected annual sales of Keytruda to hit $22.2 billion by 2025.16

Companion Diagnostics for PD-1 based therapies

Agilent’s PD-L1 IHC 22C3 pharmDx is a qualitative immunohistochemical assay using Monoclonal Mouse Anti-PD-L1, Clone 22C3 intended for use in the detection of PD-L1 protein in formalin-fixed, paraffin-embedded (FFPE) non-small cell lung cancer  (NSCLC), in paraffin and formalin-fixed stomach adenocarcinoma, gastric or gastroesophageal junction (GEJ) adenocarcinoma, esophageal squamous cell carcinoma (ESCC), cervical cancer, urothelial carcinoma, and head and neck squamous cell carcinoma (HNSCC) tissues using EnVision FLEX visualization system on Autostainer Link 48.17

PD-L1 protein expression in NSCLC is determined by using Tumor Proportion Score (TPS), which is the percentage of viable  tumor cells showing partial or complete membrane staining at any intensity. PD-L1 protein expression in gastric or GEJ adenocarcinoma, ESCC, cervical cancer, urothelial carcinoma and HNSCC is determined by using Combined Positive Score (CPS), which is the number of PD-L1 staining cells (tumor cells, lymphocytes, macrophages) divided by the total number of viable tumor cells, multiplied by 100. PD-L1 IHC 22C3 pharmDx is indicated as an aid in identifying NSCLC, gastric or GEJ adenocarcinoma, ESCC, cervical cancer, urothelial carcinoma  and  HNSCC patients for treatment with KEYTRUDA® (pembrolizumab). Please refer to the full intended use of PD-L1 IHC 22C3 pharmDx for indications and PD-L1 expression levels. This year, Agilent just has released its PD-L1 kit for the full automation platform called OMNIS, for now only to lung indication.17

Currently, there are numerous other checkpoint inhibitors and activators in clinical development. Continuing in 2017, the FDA granted accelerated approval to the PD-L1 inhibitor durvalumab (Imfinzi®) for the treatment of advanced or metastatic urothelial carcinoma. Other approved PD-L1 inhibitors include atezolizumab (Tecentriq®), and avelumab (Bavencio®).12,18

Summary

Thousands of active agents based on a variety of immuno-oncology mechanisms of action have been studied making this class of therapy a significant part of the pipelines to be launched by the pharma industry. Perhaps most notable, the current research focus relies less on clinical research than on basic and preclinical research where most active agents are presently positioned.

Globally, more and more companies are getting involved in immuno-oncology research – a fact that reflects the importance and growth of the field over the last ten years. And although we still have a long way to go, it has become a pillar of cancer therapy, enabling the treatment of aggressive cancers  and bringing long-lasting survival benefits to patients whose tumors seemed untreatable only a few years ago.19

Precision medicine, companion diagnostics testing, and immune-oncology therapies in general will take on a much larger role in the future of cancer treatment. As artificial intelligence and deep learning is anticipated to make increasing contributions in this market, we can expect surprising innovations in the coming years that will radically change our relationship with cancer.

 

Lucas Barone is a biomedical professional developing business in Cancer Diagnostics for 10 years.  He has a postgraduate in Marketing and an MBA in Health Tech. He is a technology enthusiastic consulting several healthcare startups around the globe.

 

 

 

References

  1. Oiseth, SJ & Aziz, 2017. Cancer immunotherapy: a brief review of the history, possibilities, and challenges ahead. J Cancer Metastasis Treat, 3:250-61
  2. Decker, WK et 2017. Cancer immunotherapy: Historical Perspective of a Clinical Revolution and emerging Preclinical Animal Models. Frontiers in Immunology, 8:829
  3. Co-development of trastuzumab (Herceptin, Roche/Genentech) and the immunohistochemistry (IHC) assay, HercepTest (Dako/Agilent); https://www.roche.com/products/product-details.htm?productId=b6406929-997b-4565-9ffa-cbe89324bbf5
  4. How Herceptin Works: The Mechanism of Action; https://www.breastcancer.org/treatment/targeted_therapies/herceptin#:~:text=Herceptin%20works%20by%20attaching%20itself,of%20an%20immune%20targeted%20therapy.
  5. From the National Research Council, “Precision medicine refers to the tailoring of medical treatment to the individual characteristics of each patient. It does not literally mean the creation of drugs or medical devices that are unique to a patient, but rather the ability to classify individuals into subpopulations that differ in their susceptibility to a particular disease or in their response to a specific treatment. Although the term “personalized medicine” is also used to convey this meaning, that term is sometimes misinterpreted as implying that unique treatments can be designed for each individual. It should be emphasized that in “precision medicine,” the word “precision” is being used in a colloquial sense, to mean both “accurate” and “precise.”, see https://www.ncbi.nlm.nih.gov/books/NBK92148/.
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  2. European Medicines Agency, Avastin, bevacizumab, https://www.ema.europa.eu/en/medicines/human/EPAR/avastin
  3. Jiang, T, Zhou, C & Ren, 2016. Role of IL-2 in cancer immunotherapy. OncoImmunology, 5(6): e1163462
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  5. European Medicines Agency, Provenge, sipuleucel-T, https://www.ema.europa.eu/en/medicines/human/EPAR/provenge
  6. National Cancer Institute 2018. Immune Checkpoint Inhibitors, https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/checkpoint-inhibitors
  7. American Cancer Society, How Immunotherapy Is Used to Treat Cancer, https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/what-is-immunotherapy.html
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  11. https://wbarrons.com/articles/mercks-keytruda-will-become-best-selling-drug-worldwide-research-group-says-51570204530
  12. https://agilent.com/en/product/pharmdx/pd-l1-ihc-22c3-pharmdx/pd-l1-ihc-22c3-pharmdx-for-autostainer-link-48-94449
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