Atara Biotherapeutics Stock Plunges as Company Stops Development of Kidney Drug PINTA 745

Atara Biotherapeutics Stock Plunges as Company Stops Development of Kidney Drug PINTA 745y
December 14, 2015
By Alex Keown, Breaking News Staff

SOUTH SAN FRANCISCO – Atara Biotherapeutics stock plunged this morning after the company announced its end stage renal disease experimental treatment PINTA 745 failed to meet its endpoints during a Phase II proof of concept trial.

Atara’s has lost more than 37 percent of its value since the company announced the drug failure. Stock hit a morning low of $19.50 per share, down from its previous close of $33.20 per share.

PINTA 745 is a peptibody that binds myostatin and inhibits its corresponding signal transduction, thereby blocking the negative regulation of skeletal muscle growth. The therapy was being studied for its effect on the treatment of protein energy wasting in patients with end stage renal disease. Trial results did not meet its primary endpoint, defined as the percent change from baseline in Lean Body Mass (LBM) as measured by Dual Energy X-Ray Absorptiometry (DXA) at week 12 following weekly treatment with PINTA 745, the company said this morning. Additionally, PINTA 745 did not improve physical function, measures of glycemic control and markers of inflammation, the company said. As a result, Atara is suspending further development of PINTA 745.

It was only a little more than a month ago an article published in the “International Journal of Obesity” showed the efficacy of PINTA 745 for the treatment of type II diabetes in mouse models.

"We are very disappointed that PINTA 745 did not meet the primary endpoint of this Phase II clinical trial. These data are unambiguous and contrast with prior clinical and preclinical results," Isaac Ciechanover, president and chief executive officer of Atara Biotherapeutics said in a statement.

Atara said research into PINTA 745 from inception until the trial failure had a cost of approximately $10 million.

With PINTA 745 discontinued, Atara said it will not focus its clinical efforts on its portfolio of clinical stage oncology and immunotherapy product candidates, including its epstein-barr virus (EBV) Targeted Cytotoxic T-Lymphocyte (EBV-CTL), which received breakthrough therapy designation in rituximab refractory EBV associated post-transplant lymphoproliferative disorders after allogeneic hematopoietic cell transplant. The therapeutic is in two ongoing Phase II trials for EBV malignancies. Atara is also developing Cytomegalovirus (CMV) Targeted Cytotoxic T-Lymphocytes, which is in two Phase II clinical trials for refractory CMV infections that occur in patients who have received an allogeneic hematopoietic cell transplant. Another therapy in Atara’s developmental pipeline is its Wilms' Tumor 1 Targeted Cytotoxic T-Lymphocytes, which is in two ongoing Phase I clinical trials assessing safety and initial anti-tumor efficacy in patients with hematologic malignancies. Atara’s other clinical-stage program is STM 434, an activin inhibitor, which is in an ongoing Phase I clinical trial assessing safety and initial anti-tumor efficacy in patients with ovarian cancer and other advanced solid tumors.

In October, STM 434 was granted orphan drug designation by the U.S. Food and Drug Administration (FDA). The designation is awarded to novel drugs and biologics which are defined as those intended for the treatment or prevention of rare diseases and disorders that affect fewer than 200,000 people in the U.S. STM 434 is a fusion protein that binds Activin A and other ligands of the ActR2B receptor.

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