Are PFTs Still the Gold Standard? The Future Role of Imaging Biomarkers in Respiratory R&D

Pulmonary function tests still anchor a large part of respiratory development. They are familiar, widely accepted, and deeply embedded in protocol design. In asthma, COPD, interstitial lung disease, and other pulmonary programs, spirometry and related assessments remain standard because they offer continuity: continuity with past studies, with clinical practice, and with regulatory expectations.

That alone explains why sponsors continue to rely on them. They provide a shared language. Investigators know how to interpret them. Regulators know how to contextualize them. Teams can compare results across programs without having to reinvent the evidentiary framework each time.

But that does not make them complete. And in respiratory R&D, completeness matters more than it once did.

Why PFTs Debate Matters for Sponsors

For sponsors, this is not a theoretical question. It sits right in the middle of development strategy. If a chosen endpoint is too broad, too blunt, or too slow to move, it can weaken confidence in an otherwise promising therapy. In some cases, it can distort the program’s direction altogether.

Respiratory trials are especially exposed to that risk. Heterogeneity is common, disease burden is often unevenly distributed, and treatment effects may appear regionally before they become obvious in whole-lung function. That creates a tension sponsors increasingly recognize: the endpoints that are easiest to defend are not always the ones that are most sensitive to early or localized change.

So the debate is no longer about whether PFTs are useful. They clearly are. The question is when they stop being sufficient on their own—and what imaging biomarkers can add when the conventional framework begins to flatten the signal.

What PFTs Still Do Well

PFTs still do a great deal well. They are standardized, clinically familiar, and comparatively easy to integrate into multicenter development programs. Measures such as spirometry and DLCO continue to provide a practical foundation for assessing global impairment, monitoring progression, and quantifying change over time. That matters in respiratory trials, where comparability across sites and studies is often essential.

They also retain something that newer biomarkers do not automatically have: regulatory legitimacy built over decades. A shift in FEV1 or DLCO may not tell the whole story, but it is readily understandable. That matters when sponsors are building datasets that need to stand up not only in internal review meetings, but in front of regulators and external clinical audiences as well.

And there is another point worth making. PFTs are efficient. They can be deployed broadly, interpreted quickly, and operationalized without the same infrastructure burden as advanced imaging. In a real-world development environment, that practicality still counts for a lot.

Where Global Lung Metrics Reach Their Limits

The weakness of global lung metrics becomes most visible in heterogeneous disease. A single summary value can hide meaningful regional variation—sometimes enough to dull the apparent treatment effect. In COPD, one lung region may deteriorate while another remains relatively stable. In ILD, progression may not be spatially uniform. In severe asthma, localized ventilation abnormalities may evolve in ways that global measures only partially reflect.

That does not mean the metric is wrong. It means its field of vision is narrow. A whole-lung measure tells you how the organ performs in aggregate; it does not necessarily tell you where the burden sits, where improvement begins, or where a mechanism may already be active. In early development, that limitation can be costly, especially when sponsors are trying to decide whether a signal is real enough to justify further investment.

This is where imaging starts to become more than an exploratory layer. It becomes a way of recovering detail that global metrics cannot easily preserve.

What Imaging Biomarkers Add to Respiratory Trials

Imaging biomarkers add spatial depth. Instead of summarizing the lung through a single functional average, they allow teams to look at what is happening region by region—where ventilation is impaired, where structural abnormalities are concentrated, how perfusion behaves, and whether treatment is changing one area more than another. 

Quantitative pulmonary imaging has advanced enough that this is no longer a niche scientific argument; it is becoming part of how sponsors think about evidence quality.

That shift matters because many respiratory diseases do not behave globally. They behave patchily, asymmetrically, or in patterns that evolve over time. Imaging biomarkers can help sponsors see those patterns rather than averaging them away.

And sometimes that is the difference between a weak-looking program and one with a credible proof-of-concept story.

In Which Respiratory Programs Imaging Biomarkers Matter Most

Some respiratory indications make the case for imaging more strongly than others. COPD and emphysema are obvious examples. Disease burden is often regionally distributed, which means whole-lung function can underrepresent local pathology or local response to therapy. Quantitative imaging has become increasingly useful for characterizing emphysema patterns, functional small airway disease, and air trapping in ways spirometry cannot fully localize.

Interstitial lung disease is another area where imaging biomarkers have clear relevance. When progression is subtle or spatially uneven, structural and regional imaging can offer a more sensitive way to track change and interpret how a therapy is affecting disease behavior. In practice, that can help sponsors understand not only whether progression is slowing, but where and how that change is occurring.

Asthma adds a slightly different case. Here, imaging is often most helpful in selected phenotypes—particularly where small airway dysfunction or localized ventilation defects are part of the mechanism being studied. It may not dominate the endpoint strategy, but it can sharpen it.

PFTs vs Imaging Biomarkers: Complement or Replacement?

At this stage, “complement” is the more credible answer. PFTs remain foundational because they are accepted, familiar, and operationally efficient. Imaging biomarkers do something different. They add resolution, context, and sometimes earlier visibility into treatment effect.

The strongest respiratory programs are increasingly built around that distinction. Global metrics still provide broad interpretability and continuity with historical evidence. Imaging adds depth where depth is needed.

So the real question is not whether one replaces the other. It is whether sponsors are building endpoint strategies that are too dependent on a single type of evidence.

Operational Challenges of Using Imaging Biomarkers at Scale

The scientific case for imaging biomarkers is often persuasive. The operational case is harder. Once imaging becomes part of a multicenter respiratory trial, the program has to absorb a new layer of complexity: acquisition protocols, scanner variability, image quality management, centralized analysis, and reproducibility across sites. What looks elegant in a single-center study can become fragile very quickly when scaled.

That fragility usually appears in familiar places. One site acquires differently. Another follows timing rules inconsistently. Quantitative analysis drifts if central review is weak or if harmonization standards are not clear early enough. In imaging-based endpoint strategies, these are not background nuisances—they can directly affect whether the endpoint remains defensible.

This is why implementation discipline matters so much. Imaging biomarkers are not just technical add-ons. They require operational design that is strong enough to preserve the scientific value they promise.

Why choosing PFTs or Imaging Biomakers Has Become a Strategic Decision for Sponsors

This has become a strategic issue because endpoint sensitivity affects more than data. It affects portfolio confidence. A program that can detect localized response earlier may move faster internally than one waiting for broad functional changes to emerge. In a competitive respiratory pipeline, that difference can alter investment decisions, sequencing decisions, and how aggressively a sponsor chooses to develop a molecule.

There is also the matter of differentiation. As respiratory development grows more phenotype-driven and more selective, the evidentiary framework itself becomes part of the strategic positioning of the program. A sponsor that captures signal more convincingly is not simply generating cleaner data—it is often building a stronger development narrative.

In that sense, the endpoint question is no longer confined to statistics or operations. It sits much closer to core R&D decision-making than it used to.

Why Sponsors Turn to Specialized Imaging Partners

Most sponsors do not need to be convinced that imaging is interesting. What they need is a way to use it without introducing avoidable complexity or weakening consistency across sites. That is where specialized imaging partners tend to matter most.

Their value is not just technical. It is structural. They help standardize acquisition, centralize interpretation, maintain quantitative consistency, and build imaging workflows that are compatible with real development timelines. In other words, they make imaging biomarkers more usable.

And in a field where respiratory datasets can become fragile very quickly, that usability can be the difference between exploratory insight and decision-grade evidence.

PFTs Remain Foundational, but the Future Is More Regional and More Quantitative

PFTs are still foundational. That has not changed. They remain central to respiratory trial design because they are practical, familiar, and regulator-facing in a way few other tools are.

But the future is clearly moving toward a more layered model of evidence. Sponsors are increasingly asking for more than a global readout. They want to know where the disease sits, where the treatment is acting, and whether a weak global shift is hiding a more meaningful local response.

That is why regional and quantitative imaging biomarkers are gaining ground. Not because they make PFTs irrelevant, but because they make respiratory trials more informative. And in modern R&D, more informative evidence is often better evidence.

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