Non-Oncology Applications: 7 of 14

Respiratory Disease

This category covers non-cancer diseases of the lungs and airways, including chronic obstructive pulmonary disease, asthma, and conditions that progressively scar and stiffen lung tissue. Idiopathic pulmonary fibrosis is one of the most serious examples.

The lung is not easy to sample. A doctor can pass a flexible tube down the airway, but that reaches only certain areas and may collect too little tissue to give a clear answer. The other option can be surgery under general anesthesia, which is a major procedure for someone whose breathing is already poor. Many lung diseases are therefore diagnosed from scans and breathing tests without ever examining lung tissue directly.

Breathing tests are cheap, immediate, and clinically meaningful because they measure how well someone can move air. What they do not show very well is the biological process underneath. They may detect the result of lung scarring after damage has happened, and different diseases can produce similar breathing patterns even though their causes and future course are quite different.

That leaves several questions for circulating markers. Researchers want to tell similar-looking lung diseases apart, identify which patients are likely to worsen quickly, see whether treatment is working before months have passed, and sometimes predict an exacerbation, meaning a sudden worsening, before it happens.

The materials are familiar: short RNA pieces, circulating proteins, cell-free DNA, and packages of material released by cells. Because the lungs are directly exposed to the outside air, researchers also study samples closer to the source, including fluid washed from the airways and moisture collected from exhaled breath.

One reason the research is difficult is that labels such as chronic obstructive pulmonary disease can group together people with quite different underlying biology. The same is true of the family of lung-scarring disorders. A marker that separates a mixed patient group from healthy volunteers may only be picking up one process within that group, which can make the result hard to reproduce elsewhere.