Chronic Graft-versus-Host Disease-Associated Muscle Cramps: Severity and Response to Immunomodulatory Therapies.

Muscle cramps in patients with chronic graft-versus-host disease (cGVHD) are common and associated with impaired quality of life and symptom burden. Muscle cramps are not currently captured in the 2014 National Institutes of Health (NIH) response criteria, and thus characterization and response to immunomodulatory therapies are lacking. The objective of this study was to characterize muscle cramp frequency, duration, and pain level in patients with steroid-refractory cGVHD undergoing extracorporeal photopheresis (ECP). A single-center cohort of patients who underwent ECP for the indication of steroid-refractory cGVHD with muscle cramps at treatment initiation were followed from April 2021 to April 2023. Of 22 patients receiving ECP for cGVHD during the study period, 9 (41%) had muscle cramps at ECP initiation (6 males [66%]; median age, 59 years; range, 25 to 66 years). Seven of these 9 patients (78%) had multiple organs involved, and 7 (78%) had severe disease by the NIH Global Severity scale. Over a median treatment duration of 28 weeks (range, 10 to 48 weeks), 8 patients (89%) had decreased frequency of muscle cramps from a median of 5 episodes per week (range, 3 per day to 2 per week) to a median of <1 episode per week (range, 1 per month to 3 per week). The pain and duration of muscle cramps were not changed meaningfully. The NIH Global Severity score remained unchanged in 6 patients (67%) and was improved in 3 patients (33%). Muscle cramping is a morbid feature of cGVHD that may be sensitive to change with standard immunomodulatory therapies. Muscle cramp frequency should be further validated as a response measure in cGVHD.