Positive New, Long-Term Follow-Up Data of Asterias Biotherapeutics' AST-VAC1 Cancer Vaccine Demonstrates Prolonged Relapse-Free Survival in Patients with High-Risk Acute Myelogenous Leukemia (AML)

MENLO PARK, Calif., June 1, 2015 /PRNewswire/ -- Asterias Biotherapeutics, Inc. (NYSE MKT: AST), a biotechnology company focused on the emerging field of regenerative medicine, today announced positive, new, long-term follow-up data from a Phase 2 clinical trial of AST-VAC1 in patients with intermediate and high risk acute myelogenous leukemia (AML). AST-VAC1 is the Company's autologous (using cells sourced from the patient) telomerase-based dendritic cell cancer vaccine. AML is the most common form of acute leukemia in adults with 12,000 new cases diagnosed annually, and remains an unmet clinical need, especially in patients over the age of 60 who face poor outcomes and have limited therapies available to them. The long-term follow-up showed that more than 50% of patients who received AST-VAC1 had prolonged relapse-free survival, even patients with high-risk AML including those over 60 years old and patients in second remission.

H. Jean Khoury, MD, FACP, professor of hematology and medical oncology, and director of the Division of Hematology in the Department of Hematology and Medical Oncology at Emory University School of Medicine, presented the new long-term follow-up findings at the 2015 American Society of Clinical Oncology (ASCO) Annual Meeting during an oral presentation on Saturday, May 30, 2015.

"Many AML patients in complete remission following chemotherapy eventually relapse due to a substantial burden of remaining leukemic cells," said Dr. Khoury. "Additional therapies that are well-tolerated are needed for patients at high risk of relapse. The long-term follow-up data shows that patients tolerated AST-VAC1 treatment very well, and more importantly, relapse-free survival in this high-risk patient population continues to be encouraging. Eleven out of 19 patients (58 percent) receiving AST-VAC1 during complete remission were relapse-free with a median follow-up of 52 months. More importantly, four out of seven patients (57 percent) over the age of 60 remained in remission after a median 54 months of follow-up. These results suggest that targeting telomerase through a dendritic cell-based vaccine approach may prolong remission duration in patients with high-risk AML, and warrant additional study in future trials."

"AST-VAC1 represents the first development product from our proprietary dendritic cell immunotherapy technology platform that is designed to stimulate patients' immune systems to attack telomerase, a protein that is expressed in over 95 percent of cancers but is rarely expressed in normal adult cells," said Dr. Jane Lebkowski, President of R&D of Asterias. "Our dendritic cell immunotherapy technology is based on a unique mode of action that is complementary and potentially synergistic to immune checkpoint inhibitor drugs that have shown promising results in treating patients across multiple advanced cancers. These positive long-term findings provide additional clinical rationale that supports our focus on progressing our AST-VAC2 allogeneic (non-patient specific) dendritic cell cancer vaccine development program into a Phase 1/2a clinical trial in lung cancer, as well as pursue development strategies for the AST-VAC1 program."

Long-Term Follow-Up Results

Twenty-one patients received at least three injections of AST-VAC1 in the study, including 19 patients in clinical remission (CR); 16 in first clinical remission (CR1) and three in second clinical remission (CR2), and two patients in early relapse. Seven of the 19 patients in CR were at least 60 years old at the time of immunotherapy with AST-VAC1. Of the 19 patients who were in CR, 13 received all 12 doses of AST-VAC1 with one additional patient withdrawing consent just before the last vaccination dose. The two patients who were vaccinated with AST-VAC1 during early relapse progressed rapidly and did not receive the full dosing regimen.

Eleven of 19 patients (58 percent) in the trial remain in CR with a median duration of follow-up of 52 months from first vaccination. Four of the seven patients who were at least 60 years old at the time of immunotherapy with AST-VAC1 remain relapse free 52 to 59 months from first vaccination. The three patients who received AST-VAC1 while in CR2 were in remission as of their last follow-up of 24, 50 and 59 months. Historical results suggest that relapse-free survival in AML patients greater than 60 years old is poor with 10 percent to 20 percent surviving 60 months.

Patient immune response to telomerase after vaccination with AST-VAC1 was assessed by peptide ELISpot analysis to measure the presence of activated T-cells specific to hTERT. Positive immune responses were detected in 58% of patients.

AST-VAC1 was found to be safe and well-tolerated in this study over multiple vaccinations, with up to 32 serial vaccinations administered (median = 17). Idiopathic thrombocytopenic purpura (grade 3-4) was reported in one patient. Other toxicities (grade 1-2) included rash or headache.

"We are very encouraged by these promising new, long-term relapse findings, and excited by the opportunity of having a third clinical stage program at Asterias," said Pedro Lichtinger, President and CEO of Asterias. "AST-VAC1 becomes our most advanced clinical opportunity fitting our strategic focus on major unmet medical needs without adequate available therapies. We are forming our clinical development plan for AST-VAC1, and intend to explore all strategic alternatives to further advance this product for the benefit of patients, and to maximize value for Asterias shareholders."

Phase 2 Trial Design

The multi-center, open label trial was designed to evaluate the feasibility of AST-VAC1 manufacture and the safety and tolerability of the vaccination regimen in patients with AML who were in complete clinical remission. Additional objectives of the study were to evaluate the immune responses to AST-VAC1 and to explore the effects of vaccination on relapse in this patient population.

Patients entered the trial in their first or second clinical remission. Prior to or shortly after completing consolidation chemotherapy, patients underwent leukapheresis to harvest normal mononuclear (white blood) cells from the bloodstream for vaccine manufacture.

Patients were vaccinated weekly for six weeks, with AST-VAC1 cells administered intra-dermally, followed by a non-treatment period of four weeks, and subsequent boost injections every other week for 12 weeks. Monthly extended boost injections were then administered until their vaccine product supply was depleted or the patient relapsed.

Complementarity with Other Therapeutic Approaches to Malignancies

AST-VAC1 is intended to stimulate specific anti-tumor immune responses and the current study in AML indicates that this therapeutic vaccine can successfully induce immune responses to the tumor antigen, telomerase, even in hematological malignancies. AST-VAC1 may be used to enhance the activity of recently approved or experimental immune checkpoint inhibitors that target the CTLA4, PD1, or other pathways by providing a potent stimulator of tumor-targeting immune responses. Likewise, AST-VAC1 could complement chimeric T cell receptor therapies.  In this case, the chimeric T cell receptor therapies could serve as debulking agents facilitating remissions prior to administration of AST-VAC1. Such combinations could expand the addressable patient population for each therapeutic approach.

Conference Call and Webcast Details

Management will host a conference call and webcast at 4:30 p.m. ET on Wednesday, June 3, 2015, to discuss the new, long-term follow-up data from the Phase 2 clinical trial of AST-VAC1 and the Company's plan to maximize the asset.

For both "listen-only" participants and those participants who wish to participate in the question-and-answer portion of the call, the dial-in number in the U.S. is 877-407-8291. For participants outside the U.S., the dial-in number is 201-689-8345. To access the live webcast, go to http://asteriasbiotherapeutics.com/events-presentations/.

A replay of the conference call will be available for seven business days beginning about two hours after the conclusion of the live call. The telephone dial-in number for U.S. participants is 877-660-6853. For participants outside the U.S., the replay dial-in number is 201-612-7415. To access the replay for all callers, refer to Conference ID 13611351. An archived webcast will also be available for 30 days, and may be accessed at http://asteriasbiotherapeutics.com/events-presentations/.

About AST-VAC1

AST-VAC1 is an autologous product (using cells that come from the treated patient) consisting of mature antigen-presenting dendritic cells pulsed with RNA for the protein component of human telomerase ("hTERT") and a portion of a lysosomal targeting signal ("LAMP"). LAMP directs the telomerase RNA to the lysosome, the subcellular organelle that directs the RNA to a particular part of the cell membrane. AST-VAC1 is injected into the patient's skin; and from there the dendritic cells travel to the lymph nodes and instruct cytotoxic T-cells (T-cells that "kill" other cells) to kill tumor cells that express telomerase on their surface.  

About Asterias Biotherapeutics

Asterias Biotherapeutics, Inc. (NYSE MKT: AST) is a leading biotechnology company in the emerging field of regenerative medicine. The Company's core technologies center on pluripotent stem cells, which are characterized by the ability to become all cell types in the human body. Asterias is focused on developing therapies based on pluripotent stem cells to treat diseases or serious injuries in several medical areas where there is high unmet medical need and without adequate available therapies. Asterias' two therapeutic programs, AST-OPC1 (oligodendrocyte progenitor cells) for spinal cord injuries and AST-VAC2 (antigen-presenting allogeneic dendritic cells) for lung cancer, are based on the Company's proprietary technology platforms of Pluripotent Stem Cells and Allogeneic Dendritic Cell Immunotherapy, respectively. AST-OPC1 is currently in a Phase 1/2a clinical trial. Additional information about Asterias can be found at www.asteriasbiotherapeutics.com.  

FORWARD-LOOKING STATEMENTS

Statements pertaining to future financial and/or operating results, future growth in research, technology, clinical development, and potential opportunities for Asterias, along with other statements about the future expectations, beliefs, goals, plans, or prospects expressed by management constitute forward-looking statements. Any statements that are not historical fact (including, but not limited to statements that contain words such as "will," "believes," "plans," "anticipates," "expects," "estimates") should also be considered to be forward-looking statements. Forward-looking statements involve risks and uncertainties, including, without limitation, risks inherent in the development and/or commercialization of potential products, uncertainty in the results of clinical trials or regulatory approvals, need and ability to obtain future capital, and maintenance of intellectual property rights. Actual results may differ materially from the results anticipated in these forward-looking statements and as such should be evaluated together with the many uncertainties that affect the businesses of Asterias, particularly those mentioned in the cautionary statements found in Asterias' filings with the Securities and Exchange Commission. Asterias disclaims any intent or obligation to update these forward-looking statements.

SOURCE Asterias Biotherapeutics, Inc.

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