CHICAGO – A combination of an immunostimulatory IL-15-based agent, ALT-803, with a therapeutic monoclonal antibody (mAb) against CD20, was well tolerated and had clinical activity in patients with indolent non-Hodgkin lymphoma (iNHL), according to preliminary from a phase 1 study.
“The cancer immunotherapy breakthrough that happened several years ago continues year after year, with a plethora of different modalities of immunotherapy at our disposal,” Todd A. Fehniger, MD, PhD, said at the annual meeting of the American Association for Cancer Research.
Immunotherapy with anti-CD20 mAbs, alone or in combination with chemotherapy, is a standard therapy for iNHL patients. Since iNHL cells express CD20, targeting it with mAbs triggers antitumor responses via cell surface receptors resulting in a potent antibody-dependent cellular toxicity. However, response in patients is highly heterogeneous, with relapse within a few months in a subset of patients. In addition, chemotherapeutic combinations can be toxic and result in serious and long-term complications.
“Relapsed or refractory iNHL is not curable and treatment strategies without long-term complications are needed,” said, associate professor of medicine at Washington University, St. Louis.
In an attempt to address this, Dr. Fehniger and his colleagues combined rituximab, an anti-CD20 antibody, with a relatively new IL-15 agonist immunostimulatory agent called ALT-803.
In the phase 1 trial, the researchers enrolled patients with indolent non-Hodgkin lymphoma who had relapsed after at least 1 prior to CD20 antibody containing therapy. The study was a standard 3+3 dose escalation design with rituximab administered by intravenous infusion, 375 mg/m2 in four weekly doses, followed by a rest and four consolidation doses every 8 weeks for four cycles.
ALT-803 was administered concurrently at dose levels of 1 mcg/kg, 3 mcg/kg, and 6 mcg/kg IV followed by 6 mcg/kg, 10 mcg/kg, 15 mcg/kg, and 20 mcg/kg subcutaneously.