Subcutaneous injections of low doses of humanized anti-CD20 veltuzumab: A phase I study in chronic lymphocytic leukemia

To evaluate the potential of subcutaneous (SC) injections with anti-CD20 antibody veltuzumab in chronic lymphocytic leukemia (CLL), 21 patients received 80, 160, or 320 mg injections every two weeks x 4 doses (n=11) or 160 or 320 mg twice-weekly x 16 doses (n=10). Treatment was well tolerated with only occasional, mild-moderate, transient injection reactions. Lymphocytosis decreased in all patients (maximum decrease, 5-91%), with 12 patients obtaining \u3e50% decreases. Of 14 patients with lymphadenopathy on CT imaging, 5 (36%) achieved 14-61% reductions (sum of perpendicular diameters). By NCI-WG criteria, 2 patients achieved partial responses (10%). SC veltuzumab appeared active in all dose groups, with no obvious exposure-response relationship, despite cumulative doses ranging from 320 to 5120 mg. Overall median progression-free survival was 7.7 months; 3 patients remained progression-free \u3e1 year (2 ongoing at 2-year study completion). These data suggest further studies of SC veltuzumab in CLL are warranted