Zubac D; Center for Integrated Oncology Aachen, Germany
Sonntag T; Kranjc D; Baumann FT

Physiological Reports. 14(17):e71090, 2026 Sep.

This study examined whether cardiopulmonary exercise test (CPET)
performance parameters are associated with chronic cancer-related fatigue
in patients receiving immunotherapy checkpoint inhibitors (ICI) and
healthy controls. Also, the differences in energy expenditure of
steady-state cycling and gross efficiency were assessed during submaximal
cycling efforts. This study involved patients (n = 19, 48 +/- 13 years)
receiving PD-1, PD-L1 checkpoint inhibitors and controls of similar age (n
= 21, 49 +/- 17 years). During the first visit, data on medical history,
previous physical activity records, and CPET to voluntary exhaustion were
collected. The second visit involved body composition assessment, the
MFI-20 fatigue questionnaire, and 30-min steady-state cycling at 90% gas
exchange threshold. There were no significant differences observed between
the groups in age, stature, BMI, or resting blood pressure. Peak VO2 was
33% lower, and the group under ICI treatment had lower cycling efficiency
(22.49% vs. 20.07%, p = 0.031), compared to controls. All self-reported
fatigue items derived from MFI-20 were significantly higher in the ICI
group compared to controls (p = 0.001). The regression analysis found no
association between the self-reported general fatigue and data collected
during CPET. Patients under ICI treatment reported higher levels of
chronic fatigue, lower peak VO2, and reduced cycling efficiency.
Interestingly, variables collected during CPET did not explain
self-reported chronic fatigue, underlying the complexity of this
phenomenon.