by Jessica Baumann, Medical Director, Companion Diagnostics, Leica Biosystems
In the era of precision medicine, oncology has undergone a profound transformation. No longer reliant on one-size-fits-all treatments, clinicians now have the tools to match patients with therapies tailored to their individual biologic profiles. Central to this evolution is the development of companion diagnostics (CDx), tests that identify individuals most likely to benefit from a specific treatment. These diagnostics are not merely supportive tools; they are foundational to the success of targeted therapies.
Yet despite the critical role of diagnostics in the identification of the correct patient population, a diagnostic strategy is often treated as an afterthought introduced late in the drug development and launch process. This misalignment has led to delays in regulatory approval, fragmented clinical trial designs, and slower access to life-saving therapies. As the field of oncology continues to evolve, it is imperative that diagnostics be viewed not as ancillary, but as integral to therapeutic innovation.
The Legacy Challenge
For decades, the prevailing model in drug development prioritized therapeutic breakthroughs, with diagnostics developed only after a drug’s efficacy was established. This sequential approach created a disconnect: therapies would advance through clinical trials without a validated method for identifying the right patients. Regulatory submissions were often staggered, and market access was hindered by the absence of a diagnostic assay at launch.
This delay not only impacted timelines but also compromised the full potential of precision medicine. Without a CDx in place, oncologists lacked the means to confidently prescribe targeted therapies, leading to suboptimal patient outcomes and inefficient use of healthcare resources. According to a 2022 analysis in Nature Reviews Drug Discovery1, nearly 40% of oncology drugs approved between 2010 and 2020 lacked a validated CDx at launch, highlighting the systemic lag in diagnostic integration.
A Paradigm Shift: Co-Development from Discovery
A growing body of evidence now supports a more integrated model, one in which diagnostic assays are developed in parallel with therapies from the earliest stages of drug discovery. This co-development approach fosters alignment across biomarker strategy, clinical trial design, and regulatory planning.
When diagnostics are embedded early, they inform patient selection criteria, guide trial enrollment, and enable real-time insights into therapeutic efficacy. Regulatory agencies increasingly recognize the value of this model. Programs like the FDA’s Parallel Review initiative3 encourage simultaneous submissions of therapeutics and diagnostics, streamlining approval processes and reducing time-to-market.
Co-development also demands a shift in how stakeholders collaborate. Pharmaceutical companies, diagnostic developers, and regulatory bodies must work in concert from the outset. Biomarker identification should begin during preclinical studies, with diagnostic platforms validated alongside therapeutic candidates. This integrated workflow requires harmonized protocols, shared data systems, and joint regulatory strategies.
Real-world Impact
The benefits of early CDx integration are not theoretical; they are being realized in practice across the oncology landscape. Consider the development of trastuzumab (Herceptin) for HER2-positive breast cancer. Its success hinged on the availability of a diagnostic test to identify HER2 protein overexpression. The co-development of the drug and its CDx not only accelerated approval but also ensured that patients most likely to benefit were identified from the outset. This model has since become a benchmark for precision oncology.
More broadly, early integration of CDx into drug development has demonstrated several key advantages:
- Synchronized Clinical Trials: Trials designed with a diagnostic in mind can more effectively stratify patients, improving statistical power and reducing trial duration. A study from the Tufts Center for the Study of Drug Development2 found that biomarker-driven trials can reduce enrollment time by up to 30%.
- Accelerated Regulatory Pathways: Coordinated submissions for both the therapy and diagnostic can lead to faster approvals and earlier access for patients. The FDA’s Parallel Review program exemplifies this, allowing simultaneous review of a therapeutic and its CDx.
- Improved Clinical Decision-Making: Oncologists gain access to validated tools that support evidence-based treatment decisions, enhancing patient outcomes and reducing trial-and-error prescribing.
- Economic Efficiency: Health systems benefit from more targeted use of therapies, reducing unnecessary treatments and associated costs. A 2023 study in JAMA Oncology4 found that CDx-guided therapies reduced overall treatment costs by 20% compared with empiric approaches.
Looking Ahead: A Call to Action
The future of precision medicine depends on a shift in mindset: diagnostics must be viewed not as peripheral tools, but as central components of therapeutic development. Early integration of CDx enables a more holistic, patient-centered approach—one that aligns scientific innovation with clinical utility.
For medical directors, researchers, and regulatory professionals, embracing this paradigm means fostering deeper collaboration across disciplines, investing in biomarker discovery, and designing trials that reflect the realities of personalized care. It also means rethinking infrastructure: building systems that support data sharing, joint validation, and harmonized regulatory pathways.
As oncology continues to evolve, the co-development of diagnostics and therapies will be essential to unlocking the full promise of precision medicine. By embedding diagnostics into the heart of drug development, we can ensure that innovation translates into impact—delivering the right treatment to the right patient at the right time.
About the author: Jessica is a board-certified anatomic and clinical pathologist focusing on companion diagnostic assay development and commercialization, and digital pathology algorithm development and clinical deployment. Prior to her current role, Jessica was a pathologist and medical director at Roche Tissue Diagnostics and AstraZeneca.