South San Francisco (Press Release) – Atara Biotherapeutics, Inc. (Nasdaq:ATRA), today announced that its col­lab­o­rating investigators at Memorial Sloan Kettering Cancer Center (MSK) presented clin­i­cal data on cyto­toxic T lym­pho­cytes (CTL) activated against Wilms' Tumor 1 (WT1-CTL) at the 15th Inter­na­tional Myeloma Workshop in Rome, Italy. The WT1-CTL prod­uct can­di­date targets cancers expressing the Wilms Tumor 1, or WT1, an­ti­gen. The data is derived from the treat­ment of patients with re­lapsed-refractory Multiple Myeloma (MM), in­­clud­ing Plasma Cell Leukemia (PCL), with WT1-CTL after allogeneic hematopoietic cell trans­plan­ta­tion (alloHCT). Dr. Guenther Koehne, MD, and colleagues, presented the fol­low­ing top-line clin­i­cal data from an ongoing phase 1 study:

• WT1, the tumor associated antigen, was detected on malignant plasma cells in those patients tested.
• The subjects were treated with alloHCT followed by administration of three infusions of WT1-CTLs.
• By one year, of seven subjects with relapsed-refractory MM or PCL receiving an alloHCT and treated with WT1-CTLs, three achieved a complete remission (CR), one achieved a partial response (PR), two had stable disease (SD) and one had progressive disease.
• Adverse events reported were consistent with those typically observed in this transplant population.

The details of the poster presentation are below:

Title: Wilms' tumor 1 protein is highly expressed on malignant plasma cells and provides a novel target for immuno­therapeutic ap­proaches
Publication Number: PO-351
Session Type: Poster Session
Presenter: Guenther Koehne M.D., PhD.

In June 2015, Atara Bio licensed from MSK exclusive, world-wide rights to three clin­i­cal stage, allogeneic T-cell ther­a­pies for the treat­ment of cancers and persistent viral in­fec­tions, in­­clud­ing WT1-CTL. The WT1-CTL prod­uct can­di­date is being developed as a poten­tial third party, donor-derived, "off-the-shelf" T-cell prod­uct can­di­date designed to target and destroy cancer cells that overexpress WT1 protein.

About Multiple Myeloma and PCL

Multiple Myeloma, a malig­nan­cy of the plasma cell, is the second most common cancer of the blood-forming system with approx­i­mately 26,850 new cases and 11,240 deaths esti­mated in the US for 2015. Of those new cases, approx­i­mately two to four per­cent are PCL, with an aggressive clin­i­cal course. Median over­all survival for PCL is 4.5-12.6 months.

About WT1-CTL

The WT1-CTL prod­uct can­di­date targets cancers expressing the an­ti­gen Wilms Tumor 1, or WT1. WT1 is an intracellular protein that is overexpressed in a number of cancers, in­­clud­ing acute myeloid leukemia, or AML, multiple myeloma, or MM, and non-small cell lung, breast, pancreatic, ovarian, and colorectal cancers. The WT1-CTL prod­uct can­di­date is cur­rently being studied in two ongoing Phase 1 clin­i­cal studies to test safety and initial anti-tumor efficacy of donor derived WT1-CTL in patients with AML and multiple myeloma. (NCT00620633 and NCT01758328).

About Atara Biotherapeutics, Inc.

Atara Biotherapeutics, Inc. is a bio­pharma­ceu­tical com­pany focused on devel­op­ing inno­va­tive ther­a­pies for patients with debilitating diseases. Atara Bio's pro­grams in­clude molecularly targeted prod­uct can­di­dates and T-cell prod­uct can­di­dates. Molecularly targeted prod­uct can­di­dates in­clude PINTA 745, STM 434 and ATA 842, members of the TGF-beta family of proteins that target myostatin and activin, and have dem­onstrated the poten­tial to have thera­peutic benefit in a number of clin­i­cal indi­ca­tions. T-cell prod­uct can­di­dates in­clude EBV-CTL, CMV-CTL and WT1-CTL.

Forward-Looking Statements

This press release con­tains or may imply "forward-looking state­ments" within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Because such state­ments deal with future events and are based on Atara Bio's current ex­pec­ta­tions, they are subject to various risks and un­cer­tain­ties and actual results, per­for­mance or achieve­ments of Atara Bio could differ materially from those described in or implied by the state­ments in this press release. For example, forward-looking state­ments in­clude state­ments regarding the clin­i­cal devel­op­ment of prod­uct can­di­dates and Atara Bio's collab­o­ra­tion with MSK. These forward-looking state­ments are subject to other risks and un­cer­tain­ties, includ­ing those discussed under the heading "Risk Factors" in Atara Bio's quarterly report on Form 10-Q filed with the Securities and Exchange Com­mis­sion (SEC) on August 6, 2015, in­­clud­ing the documents incorporated by reference therein and sub­se­quent filings with the SEC. Except as other­wise required by law, Atara Bio dis­claims any intention or obli­ga­tion to update or revise any forward-looking state­ments, which speak only as of the date hereof, whether as a result of new in­for­ma­tion, future events or cir­cum­stances or other­wise.

Source: Atara Biotherapeutics.