Atara Biotherapeutics, Inc. has entered into a clinical trial collaboration agreement with Merck to evaluate Atara’s allogeneic Epstein-Barr virus (EBV)-specific cytotoxic T lymphocytes (CTL), or ATA129, in combination with Merck’s anti-PD-1 (programmed death receptor-1) therapy, KEYTRUDA (pembrolizumab), in patients with platinum resistant or recurrent EBV-associated NPC. The Phase 1/2 trial will evaluate the safety, pharmacokinetics, pharmacodynamics, and preliminary efficacy of the combination.
 
Atara Bio’s ATA129 is an investigational therapy in which a healthy donor’s T-cells are stimulated to recognize EBV antigens, or viral proteins, expressed in the cells of certain liquid and solid tumors. Phase I and II trials in patients with a variety of EBV-positive malignancies including 14 patients with chemotherapy refractory, metastatic NPC, showed radiographic response was observed and EBV-CTLs were also shown to expand after administration without chemotherapy. Recent studies suggest that EBV upregulates the transcription of PD-L1 in EBV-associated solid tumors such as NPC and gastric cancer, suggesting the potential for synergy in combination with anti-PD-1 therapies, such as KEYTRUDA.
 
KEYTRUDA is a humanized monoclonal antibody that works by increasing the ability of the body’s immune system to help detect and fight tumor cells. KEYTRUDA blocks the interaction between PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes which may affect both tumor cells and healthy cells.
 
“Both ATA129 and KEYTRUDA have shown evidence of objective radiographic responses in NPC, and there is a strong biologic rationale to combine these therapies as their complementary mechanisms of action may enhance the anti-tumor activity,” said Chris Haqq, M.D., Ph.D., executive vice president of R&D and chief scientific officer of Atara Bio.