A combination agent composed of the two human monoclonal antibodies VAK694 (VAK296), targeting interleukin-4 (IL-4), and dectrekumab, targeting IL-13, that can potentially be used to block signaling mediated by IL-4 and IL-13. Upon intravenous administration of the anti-IL-4/IL-13 combination agent QBX258, the two antibodies VAK694 and dectrekumab target and block the activity of the two cytokines IL-4 and IL-13, respectively, which prevents IL-4/IL-13-mediated signaling. In patients with breast cancer related lymphedema (BCRL), this agent may prevent lymphedema-associated effects, such as fibrosis, hyperkeratosis, the deposition of fibroadipose tissue, fluid accumulation, limb swelling, reduction of skin elasticity, and pain. By reducing the excess volume, QBX258 may improve lymphatic and arm functions. The development of lymphedema after lymphatic injury is associated with tissue inflammation, the infiltration of CD4-positive cells and their differentiation to the type 2 helper T-cell (Th2) phenotype. Th2 cells produce IL-4 and IL-13 that play a key role in the development of lymphedema-associated symptoms as well as other Th2-mediated diseases.