Drugs & Updates

What Are The Commonly Used Companion Diagnostics?

A companion diagnostic (CDx) is an in vitro diagnostic (IVD) device, imaging tool or drug that offers the necessary information for a treatment product’s safe and successful use. Companion testing in various diseases represents an attractive way to provide more focused and individualized treatment.

Researchers are investing significant resources in developing revolutionary medication combinations and companion diagnostics to give tailored treatments that better suit individual patients as the field of cancer continues to evolve. CDx, as defined by the FDA, are devices that help make a drug or biological product safe and effective. They are designed to assist health care professionals in determining whether the benefits of a particular therapy outweigh the potential side effects or risks.

Many stakeholders profit from the test-treatment combination, including physicians, payers, regulators, and pharmaceutical and diagnostics businesses. Most importantly, they let the patient benefit from the highest probability of responding to the medication.

A companion diagnostic test is essentially the conversion of a prototypic biomarker test that has shown forecasting value in terms of effectiveness in early clinical trials into a highly validated test endorsed by a Health Authority with stringent analytical validation and clinical performance requirements. Parallel to the treatment solution, the companion diagnostic test is produced with the ultimate goal of demonstrating clinical benefit in a pivotal registrational trial for a specific therapeutic medication and illness indication.

Trastuzumab was approved in 1998, paving the way for companion diagnostics. During its development, scientists discovered that the treatment only helped women whose breast cancers overexpressed the v-erb-b2 avian erythroblastic leukemia viral oncogene homolog 2, ERBB2, also known as HER2 receptor. Because the drug is intended to target the protein, it was not surprising that this made it necessary to develop an in vitro diagnostic device to precisely and reproducibly identify HER2.

What are some of the difficulties associated with companion diagnostics?

  • One goal is to gain a scientific understanding of how the analyte relates to the medicinal product’s use. It may be possible to achieve such knowledge via hypothesis-driven biologic insights gleaned during the making of targeted treatments. It could also emerge from an entirely empirical (but well-studied) analyte-drug effect association.
  • Another issue is coordinating the timely availability and resources to get the test from the research and investigational stages to an approved version. When the analyte is crucial to the drug’s development from “day one,” such coordination is known as a problem.
  • The design, execution, and analysis of pivotal studies and trials required to establish the performance of the drug and companion diagnostic together in clinical practice is the third significant barrier. It’s good to look into the drug’s influence across all marker populations.

Developing Companion Diagnostics

The development of a Companion diagnostic test involves six critical stages, all of which must be coordinated with the effect of the drug:

  • Analytical validation
  • Scientific validation
  • Clinical validation
  • Demonstration of clinical utility
  • Authorization for marketing
  • Post-Commercialization & Marketing

The latest updates to our collection of FDA-approved comprehensive genomic profiling assays and companion diagnostic approvals across several malignancies are listed below.

  • For Non-Small Cell Lung Cancer (NSCLC): The biomarkers detected are EGFR exon 19 deletions and exon 21 (L858R) alterations. Therapy for this is EGFR inhibitors which FDA approves—approved in March 2022.
  • Solid tumor: The biomarkers detected are MSO-High. Therapy for this is Keytruda (Pembrolizumab). For individuals with advanced NSCLC tumors, pembrolizumab, a humanized monoclonal immunoglobulin G4 kappa isotype antibody against PD-1, proved anticancer effective in Phase-I clinical trials. It was approved in February 2022.
  • Melanoma: The biomarkers detected are
  1. BRAF V600E: Therapy is BRAF inhibitors, approved in November 2021.
  2. BRAF V600E and V600K: Therapy is Mekinist (Trametinib) or BRAF/MEK inhibitor combinations.

Patients with malignancies that overexpress the epidermal growth factor receptor (EGFR) are treated with cetuximab (Erbitux, Bristol-Myers Squibb) and panitumumab (Vectibix, Amgen) in colorectal cancer. EGFR pharmDx companion diagnostics identify patients who overexpress EGFR. Cetuximab and panitumumab were approved simultaneously due to this test, which was used to validate the medicines.

KRAS mutation as a therapy-directing marker in colorectal cancer emerged late; the revelation that this marker may identify patients who would likely not benefit from cetuximab and panitumumab developed after the medications became available. KRAS mutation testing is now addressed on medicine labels without reference to a specific test for safety reasons, as it is critical to minimize unnecessary exposure to potentially harmful pharmaceuticals. The ability to test for KRAS mutations is unclear to identify patients who will benefit from a well-defined therapeutic benefit.

Physicians can use companion diagnostics to select patients who might benefit from FDA-approved therapy alternatives. Companion diagnostics also give information that is crucial for the effective and safe use of targeted therapies since the number of targeted cancer therapeutic objectives and clearances in oncology is growing fast.


Navya Koshi

Navya Mariam Koshi is a diligent, self-motivated Pharm D graduate using this platform to leverage her skills in this field to provide excellent and exceptional health care services to the public.

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