HepIII inhibits growth of primary myeloma tumors in vivo. (A) Tumors formed by cells from patients with myeloma were established in the SCID-hu host and then treated for 28 days (patients 1, 2, 4, and 5), 21 days (patients 6-8), or 14 days (patient 3) by daily injection of either PBS (□), active recombinant HepIII enzyme (■), or HepIII-generated heparan sulfate fragments (▩). At the end of the treatment period, human light chain levels in the serum of the mice were analyzed and plotted as the percentage increase or decrease over the light chain level present at the time treatment was initiated. (B) Levels of kappa light chain measured at weekly intervals in animals bearing tumor from patient 5 during treatment with PBS (–) or HepIII (-------). (C) Percentage change in tumor burden following treatment as measured by levels of human light chain in the serum of mice. Bars show the combined mean percentage change of all 8 patients plus or minus SEM following treatment with PBS, HepIII, or heparan sulfate (HS) fragments generated ex vivo by HepIII.