Photo by Linda Bartlett
The US Food and Drug Administration (FDA) has granted orphan designation to veltuzumab for the treatment of immune thrombocytopenia (ITP).
Veltuzumab is a 2nd-generation, humanized monoclonal antibody targeting CD20. The drug is being developed by Immunomedics as a treatment for ITP, other autoimmune diseases, and non-Hodgkin lymphoma.
Veltuzumab was considered active and well-tolerated in a phase 1 study of adults with ITP. The drug produced responses in about half of patients, with some responses lasting more than 4 years.
The study included 50 patients with primary ITP who had failed 1 or more types of standard therapy, had platelet levels of 30,000/μL or less, and did not have major bleeding. The patients’ median age was 54, and most were female (n=31). Eight patients had undergone splenectomy.
Patients were a median of 2 years from diagnosis. Fourteen had been diagnosed with ITP for a year or less and had received corticosteroids and/or immunoglobulins.
Thirty-six patients had chronic ITP and had received azathioprine or danazol (n=15), thrombopoietin-receptor agonists (n=10), rituximab (n=7), platelets (n=5), and/or chemotherapy (n=4).
The 34 patients assigned to cohort 1 received 2 doses of subcutaneous veltuzumab at 80 mg, 160 mg, or 320 mg, 2 weeks apart (total doses of 160 mg, 320 mg, and 640 mg, respectively). The 18 patients in cohort 2 (which included 2 rollovers) received once-weekly doses at 320 mg for 4 weeks (total dose of 1280 mg).
The researchers said veltuzumab was well tolerated. The only adverse events were grade 1-2, transient injection reactions.
Forty-seven patients were evaluable for response. Forty-seven percent (n=22) had objective responses (ORs), and 28% (n=13) had complete responses (CRs).
Responses did not differ much according to disease duration. Patients with chronic ITP had an OR rate of 42% and a CR rate of 27%. Patients who had ITP for a year or less had an OR rate of 51% and a CR rate of 29%.
The median time to relapse (TTR) did not differ much between patients with CRs and those with partial responses, but there was a sizable difference between patients with chronic ITP and those with newly diagnosed ITP.
The median TTR was 7.9 months for patients with a CR and 7.6 months for patients with a partial response. The median TTR was 6.9 months for patients with chronic ITP and 14.4 months for patients who had ITP for a year or less.
The phase 2 expansion trial of veltuzumab in ITP has completed accrual, and patients are being followed for up to 5 years.
About orphan designation
The FDA grants orphan designation to drugs that are intended to treat diseases or conditions affecting fewer than 200,000 patients in the US. Orphan designation provides the sponsor of a drug with various development incentives.
The orphan designation for veltuzumab provides Immunomedics with opportunities to apply for research-related tax credits and grant funding, assistance in designing clinical trials, 7 years of US marketing exclusivity if the drug is approved, and other benefits.
