This article draws on insights shared during a panel discussion held as part of SOPHiA GENETICS’ sponsorship at the 16^th World CB & CDx Europe Pre-Day Engager.

Every companion diagnostic (CDx) program eventually hits the same question, one that should have surfaced far earlier: when do we commit to a CDx strategy?

For BioPharma, despite a decade of growing precision medicine maturity, that timing decision remains surprisingly difficult to get right. Commit too early, before a drug’s efficacy is proven, and you risk investing in a diagnostic that never reaches patients. Wait too long, and the CDx becomes a race against regulatory timelines and commercial launch plans, rather than an integrated part of the drug development journey.

So, when is the “right” time? A recent expert panel conversation among pharma leaders working across precision medicine, regulatory affairs, and diagnostic development explored this tension. Not only when to commit to a CDx, but why a single global test rarely works, and what more collaborative and innovative models might offer instead. Interestingly, these industry expert perspectives don’t point us to one universal answer. Instead, they map out how the industry is starting to rethink CDx strategy, timing and global implementation.

The Decision That Is Bigger Than It Looks

Pairing a drug with a CDx is a strategic decision with implications that extend far beyond assay development. It means accepting a smaller eligible population in exchange for a therapy that performs better for the patients who qualify. Getting an organization aligned around that trade-off takes time… and data: early proof-of-concept evidence strong enough to justify selecting a biomarker before a development program is locked in.

That data doesn’t always exist when it’s needed, and this is where the challenge begins. When a CDx strategy isn’t defined early in the development process, shifting strategy becomes more challenging because programs, resources, and stakeholders are already committed to a different path. While the industry is addressing these questions earlier than before, significant gaps remain.

Why One Global Test Isn’t the Answer

A recurring theme during the panel discussion was how unevenly the world treats companion diagnostics, and how many different obstacles stand in the way of a single, universal test. Four challenges consistently emerged:

• Tissue scarcity: Clinical trial samples are finite, and an NGS-based test can consume most of the available tissue in an initial submission, leaving little material for the bridging and concordance studies required later.
• Limited early biomarker evidence: The data needed to support biomarker decisions is often incomplete or not available when those decisions need to be made.
• Fragmented validation and regulatory requirements: Validation expectations, platform preferences, reimbursement frameworks, and regulatory requirements can vary significantly across health systems and markets, making global alignment more complex.

Together, these challenges require pharma teams to think several moves ahead: could a lower tissue-input assay enable an initial approval, with a concordance study bridging to a global CDx later on? Could a broader NGS panel reduce the need to know the “final” biomarker upfront? These questions are far from theoretical. They reflect the everyday reality of clinical development teams seeking to maximize the value of a single dataset across multiple regulatory frameworks. Successfully navigating this landscape requires specialized expertise, which is not consistently available across every partner or every organization.

The Cost of Timing: Too Early Versus Too Late

Both extremes carry real costs, and neither is obviously worse than the other, depending entirely on where in development a company chooses to place its bet.

Investing in diagnostic development before efficacy is established carries a real financial risk. Waiting too long, however, creates a different cost: diagnostic strategies built under timeline pressures instead of by design.

According to the panel, every delay in aligning drug and diagnostic development has consequences beyond just timelines. These can ultimately affect how quickly eligible patients can be identified once a therapy reaches the market. Rather than defining a fixed timepoint for when diagnostic planning should begin, the panel emphasized a shift in mindset: the earlier reliable data can be generated, the cheaper and better-informed every downstream decision becomes. Once again, our speakers pointed to broader genomic panels as one way to mitigate the risk of this timing problem, allowing teams to defer some biomarker-specific commitments while still building the diagnostic infrastructure they will need later.

Innovative Models: Is a Hybrid CDx Approach the Answer?

If there is one question every global CDx launch eventually runs into, it’s this: what single model could serve every market at once? According to this panel discussion, the honest answer is none. At least not alone.

No single lab, anywhere in the world, can realistically serve every market with the same test in the same way. A centralized approach brings the reproducibility and regulatory certainty that trials depend on. On the other end, a decentralized, kitted approach is what actually drives adoption once a therapy launches, because labs, in most countries, want to run the test locally. One option is not better than the other; they both solve different halves of the same problem.

The interesting middle ground is combining both of them into one unified strategy. Partnerships that pair central-lab and regulatory expertise with strong in-market, decentralized distribution capabilities let pharma companies move fast toward an initial approval, while still building toward genuine global access. The stronger decentralized distribution networks and the deepest regulatory expertise rarely sit within the same organization. For organizations looking to balance these competing demands, hybrid CDx partnership models are becoming increasingly attractive. One good example is the approach SOPHiA GENETICS has developed with its diagnostic partners across the world, designed to ensure the capabilities required for a global launch, from regulatory to technical and logistical, are in place everywhere a therapy needs to reach patients, and not only in the markets where it’s easier to launch first.

What’s Ahead: The Next Twelve Months

Despite differing perspectives on timing and implementation, this panel converged around several priorities:

• Generating evidence earlier so the broader community can prepare for what’s coming.
• Strengthening the two-way dialogue between global R&D and local, in-market diagnostic teams.
• Shifting the internal narrative around CDx from an “insurance policy” to a strategic advantage.

A biomarker strategy, done well, doesn’t just reduce risk. It can open access to patient populations a therapy wouldn’t otherwise reach.

Together, these perspectives don’t point toward a single model as “the future”. It points to a hybrid one, combining a centralized approach where certainty matters most, with a decentralized one where access does, and increasingly built on partnerships that treat both halves of the equation as equally essential.

Disclaimer
The opinions expressed by the panelists are their own and may not represent the opinions of SOPHiA GENETICS and the companies they work for.