10/03/2023 Important insight for Castleman disease patients: In a recent study published in the American Journal of Hematology, members of the Center for Cytokine Storm Treatment & Laboratory (CSTL) at the University of Pennsylvania reported that interleukin-6 (IL-6) levels are not an accurate reflection of a patient’s treatment response in idiopathic multicentric Castleman Disease (iMCD) following treatment with Siltuximab. Siltuximab is often used as a treatment for iMCD patients and siltuximab targets a molecule called IL-6. When analyzing IL-6 levels in patients with iMCD, researchers found that IL-6 levels skyrocket, because the test is no longer accurate, even when the treatment was actually working. This suggests that IL-6 levels are not a good way to see if the treatment is effective. Doctors should not measure IL-6 levels after receiving siltuximab. Other tests should be used to check if treatment is helping the patients.