Figure 2.

In vivo and in vitro stability of ⁶⁴Cu encapsulation in MM-DX-929. (A) Sepharose CL4B columns were characterized using fluorescently-labeled liposome or human plasma to determine the fractions at which liposome-bound or plasma-protein-bound ⁶⁴Cu:4-DEAP-ATSC elute, respectively. Free ⁶⁴Cu is retained within the column with < 3% of recovery from elution at 100 mL of cumulative volume. Following incubation with human plasma at 37ºC for 0 h and 48 h, aliquots of MM-DX-929/plasma mixture were loaded onto the columns to separate the liposomal ⁶⁴Cu from non-liposomal ⁶⁴Cu. (B) The percentage of ⁶⁴Cu retained within the liposome was determined from (A) by dividing the ⁶⁴Cu signal recovered from MM-DX-929 in the liposome fraction by the total radioactivity recovered. (C) Mice were injected with a single dose of MM-DX-929 or ³H-MM-DX-929. At designated time points up to 48 h.p.i., a blood sample was collected via saphenous vein puncture. ⁶⁴Cu and ³H radioactivity in the plasma fraction was quantified using scintillation-counting. Data is decay-corrected. ³H serves as a stable tracer for the liposomal component of MM-DX-929 and was incorporated into the formulation as ³H-CDHE. (D) Ratio of ⁶⁴Cu-to-³H in plasma derived from (C) was plotted as a function of time post-injection.