Design and rationale of a randomized, double-blind, placebo-controlled phase III study for autologous bone marrow cell transplantation in critical limb ischemia: the BONe Marrow Outcomes Trial in Critical Limb Ischemia (BONMOT-CLI)

Background: Critical limb ischemia (CLI) is the end-stage of peripheral artery disease. Only about two thirds of patients with CLI can be revascularised, one third progresses to leg amputation with high associated morbidity and mortality. Therapeutic angiogenesis with bone marrow cells has shown promising improvement in less severe stages of peripheral ischemia. Our study evaluates the therapeutic value of bone marrow cell induced angiogenesis and arteriogenesis in severe, limb-threatening ischemia. Patients and methods: the BONe Marrow Outcome Trial in Critical Limb Ischemia (BONMOT-CLI) is a investigator-initiated, double-blinded, 1:1 randomized, placebo-controlled multi-centre study at 4 sites in Germany. Only patients with no option for revascularisation or after failed revascularisation will be included. A total of 90 patients is to be included. One arm with 45 subjects will be treated with a concentrate of autologous bone marrow cells which will be injected at 40 sites into the ischemic limb. In the placebo arm, study subjects will undergo a sham bone marrow punction and 40 saline injections. At three months, a combined primary endpoint of major amputation or persisting critical limb ischemia (no clinical or perfusion improvement) will be evaluated. Secondary endpoints are death, changes in perfusion, quality of life, walking distance, minor amputations, wound healing, collateral density and cancer incidence. Post-study follow-up is up to two years. Conclusions: The results of this first randomized placebo-controlled trial for autologous bone marrow cell therapy in CLI will clarify the value of this new therapeutic modality in a patient population with no other alternatives except major amputation.