Given the exorbitant concentration of IL-6 and its soluble receptor IL-6Rα in malignant peritoneal fluid [62], we have initiated a phase I clinical trial to assess the potential of intraperitoneal infusion of the IL-6 axis antagonist tocilizumab using indwelling catheters in the peritoneal and pleural spaces of patients with malignant ascites or pleural effusions (NCT06016179). Here, IL6 is linked to Pleural effusion.