Atara Biotherapeutics, Inc. announced that it has exclusively licensed worldwide rights to a mesothelin-targeted chimeric antigen receptor T-cell (CAR T) immunotherapy for solid tumors from Memorial Sloan Kettering Cancer Center (MSK). The most advanced program in Atara's CAR T collaboration with MSK will focus on development of a next-generation, mesothelin-targeted CAR T using novel 1XX CAR signaling domain and PD-1 dominant negative receptor (DNR) checkpoint inhibition technologies for patients with mesothelin-associated solid tumors. PD-1 DNRs are modified PD-1 receptors that lack inhibitory function and are designed to enhance CAR T efficacy in solid tumors without the need for development of a CAR T in combination with a PD-1 checkpoint inhibitor. Animal models have demonstrated that CAR T immunotherapies with a PD-1 DNR result in enhanced activity against solid tumors. Mesothelin is a solid tumor-associated antigen that is expressed at high levels on the surface of cells in aggressive solid tumors including mesothelioma, triple-negative breast cancer, esophageal cancer, pancreatic cancer and non-small cell lung cancer. Initial results from an ongoing MSK investigator-sponsored Phase 1 study (NCT02414269) of a mesothelin-targeted CAR T immunotherapy for patients with malignant pleural cancers were presented at the 2018 American Society of Gene and Cell Therapy (ASGCT) Annual Meeting and support activity and safety in patients with advanced mesothelioma2,3. This ongoing Phase 1 dose-escalation study continues to accrue patients and enhanced response rates were observed when patients were subsequently treated with pembrolizumab, a PD-1 checkpoint inhibitor. MSK is also investigating mesothelin-targeted CAR T cells for patients with advanced breast and lung cancer. Additional results from these ongoing studies are expected to be presented at upcoming scientific congresses.