The one-arm version of eLIFR-Fc is much smaller than the bivalent eLIFR-Fc (~107 kDa versus ~173 kDa; Supplementary Fig. 3b), and could be a viable alternative if needed for navigating the dense stroma of the tumor microenvironment, though as LIF is a secreted factor, deep tumor penetration may not be a prerequisite for therapeutic efficacy. The gene discussed is LIF; the disease is neoplasm.