Atara Biotherapeutics, Inc. is a clinical-stage biopharmaceutical company. The Company is focused on developing therapeutics for serious unmet medical needs, with an initial focus on muscle wasting conditions and oncology. The Company�s product candidates are biologics targeting myostatin and activin, members of the Transforming Growth Factor-Beta (TGF-B), protein superfamily, which play roles in the growth and maintenance of muscle and many other body tissues. The Company�s lead product candidate, PINTA 745, is in a Phase II clinical trial for protein-energy wasting, a condition affecting many end-stage renal disease patients. Its second product candidate is STM 434. The Company has five additional molecules in preclinical development.