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 findings 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 Dr. Fehniger, 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.