Immunomedics reports encouraging initial results from Phase I/II ITP study

At the time of reporting, nine patients were evaluable. Overall, the objective response rate was 67%, with 33% of patients having a complete response. For the subgroup of patients who did not have their spleen surgically removed prior to this study, the response rate was 100% regardless of the route of administration and across the two doses tested (80 and 120mg).

More importantly, three patients (50%) completely responded to veltuzumab and continuing to maintain their platelet levels at six weeks, six and nine months post therapy. For the three patients who had undergone splenectomy, none responded to treatment, the company said.

Approximately 11 adult chronic immune thrombocytopenic purpura (ITP) patients with platelets counts below 30 x 10(9)/L who failed at least one standard therapy have been enrolled in this study to receive two veltuzumab doses administered two weeks apart. Approximately seven patients received veltuzumab intravenously and four were given veltuzumab injections.

Both routes of veltuzumab administration produced B-cell depletion. One patient had an infusion reaction to intravenous dosing and discontinued treatment. Approximately two patients had minor immunogenic response to veltuzumab after intravenous infusions. Otherwise, veltuzumab was well tolerated with no other safety issues.

Cynthia Sullivan, president and CEO of Immunomedics, said: We are very encouraged by the level and duration of response so far, especially in patients with no splenectomy. The study is continuing, with the next cohort of patients to receive subcutaneous injections at a higher dose of 320mg.