Atara gets FDA approval to start two phase 3 studies to assess tabelecleucel in patients with EBV+PTLD

The Company plans to initiate these studies imminently. Tabelecleucel is Atara's off-the-shelf T-cell immunotherapy in development for the treatment of EBV+PTLD, as well as other EBV associated hematologic and solid tumors.

“We are delighted to have received FDA clearance to start the tabelecleucel Phase 3 clinical studies,” said Isaac Ciechanover M.D., Chief Executive Officer and President of Atara Biotherapeutics.

 “This achievement included extensive collaboration with the FDA under Breakthrough Therapy Designation and we expect tabelecleucel to be the first off-the-shelf T-cell immunotherapy to begin Phase 3 clinical development in the U.S.  Receiving clearance to initiate these studies is a significant milestone for Atara, and we expect to open our initial clinical sites imminently to serve the substantial unmet need for patients with this life-threatening condition.”

Atara’s tabelecleucel Phase 3 program consists of two global, multicenter, open-label studies:

for the treatment of patients with EBV+PTLD following allogeneic hematopoietic cell transplant (HCT) after failure of rituximab (MATCH), and

for patients with EBV+PTLD following solid organ transplant (SOT) after failure of rituximab or after failure of rituximab plus chemotherapy (ALLELE).

The Phase 3 studies are expected to open for enrollment in the U.S. imminently and will later expand to include sites in the EU, Canada and Australia.

Results from the first tabelecleucel Phase 3 study to reach the primary endpoint are expected to be announced in the first half of 2019. Atara also plans to submit a tabelecleucel Conditional Marketing Authorization (CMA) application in the EU for patients with rituximab-refractory EBV+PTLD following HCT during the first half of 2019.

In addition, Atara plans to continue working closely with the FDA, Health Canada and other global health authorities to make tabelecleucel available to patients as expeditiously as possible.

The primary endpoint of both the MATCH and ALLELE studies is the confirmed objective response rate (ORR), defined as the percent of patients achieving either a complete or partial response to tabelecleucel treatment confirmed after the initial tumor assessment showing a response. The protocols are designed to rule out 20% ORR as the null hypothesis. For example, assuming anticipated enrollment of 35 patients in MATCH, an ORR above approximately 37% would be expected to meet the primary endpoint. In ALLELE, each of two cohorts with an anticipated enrollment of 35 patients will be analyzed independently using the same statistical methodology.

Secondary endpoints for both the MATCH and ALLELE studies include duration of response, overall survival, safety, quality of life metrics, and other data in support of potential health economic benefits.

Atara also recently announced positive interim results from an ongoing multicenter expanded access protocol (EAP) study of tabelecleucel for patients with EBV associated cancers, which were presented at the 59th American Society of Hematology (ASH) Annual Meeting.

 The EAP study findings presented at ASH in patients from the Phase 3 EBV+PTLD study populations were consistent with the tabelecleucel profile observed in previously reported Phase 2 studies conducted by Memorial Sloan Kettering Cancer Center.

With the EAP study, Atara has also displayed the ability to rapidly deploy banked, off-the-shelf T-cells to transplant patients in a multicenter setting, and the Company will continue to leverage this experience in the tabelecleucel Phase 3 studies.