Analyzing the volatile organic compounds (VOCs) expelled in the breath can help clinicians detect and monitor gastrointestinal graft-versus-host disease (GI GVHD) in patients who have undergone an allogeneic hematopoietic cell transplantation (alloHCT). The results of this pilot study were published in Blood Advances.
“The ultimate hope is that, in the future, breath analysis will be a novel and easy test that can identify and monitor changes in GVHD,†said lead study author Betty Hamilton, MD, of the Cleveland Clinic. “Breath analysis can be done in the clinic and does not require any invasive procedures or hospitalizations and may potentially substitute endoscopies with biopsies as a tool to monitor early changes in GVHD.â€
VOCs generated during pathologic processes have been used to diagnose a variety of other diseases, Dr. Hamilton explained. Given the role of the microbiome in GVHD, the investigators hypothesized that micro-organisms producing volatile metabolites may alter VOCs expelled in breath in patients with GI GVHD. These alterations could be detected on mass spectrometry to determine the presence and changes in GI GVHD.
This prospective, single-institution, pilot study enrolled 29 patients (age ≥12 years) who had no active respiratory infection and had received alloHCT for any diagnosis, with any conditioning, and with any donor source. The study included:
- 19 patients who had grade 2-4 GI GVHD
- 10 patients with no GVHD at day 100 post-alloHCT
As an additional control group, researchers also collected breath samples from 10 healthy controls who were present in a GVHD environment (e.g., health care staff and caregivers) to evaluate potential background environmental factors.
The samples were then analyzed for the presence of several prespecified VOCs, including acetaldehyde, benzene, ethanol, and ammonia.
There were no significant differences in baseline characteristics between patients with and without GI GVHD, the researchers noted, with groups well balanced in regards to sex (p=0.41), race (p=0.53), age at transplant (p=0.89), or comorbidity index (p=0.54).
All patients received a standard protocol of prophylactic antibiotics (trimethoprim-sulfamethoxazole at the start of conditioning through engraftment, followed by amoxicillin or azithromycin during immunosuppression).