Griffen Securities Positive on ZIOPHARM's (ZIOP) Latest Membrane-Bound IL-15 Data; Affirms at 'Buy'

November 17, 2016 7:42 AM EST
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Griffen Securities reaffirms ZIOPHARM Oncology, Inc. (Nasdaq: ZIOP) at Buy with a price target of $21 after the company announced the publication of data demonstrating enhanced persistence of genetically modified T cells targeting leukemia through utilization of its non-viral Sleeping Beauty (SB) system to co-express membrane-bound IL-15 (mbIL15) and a CD19-specific chimeric antigen receptor (CAR).

The firm offered the following commentary today:

Membrane-bound IL-15 (mbIL15) provides the key signal to youthful and persistent T cells. Ziopharm worked for more than two years to create T cells that would be able to attack an existing cancer and provide a lasting immune response against disease recurrence. As described in a new publication, the Company selected interleukin-15 (IL-15), a cytokine that increases T-cell persistence, to create a new signal via its collaboration with Intrexon. The approach involved fusing IL-15 to the IL-15 receptor a subunit so the fusion protein would provide a constant stimulus to support T cell persistence even in the absence of a tumor-associated antigen. This strategy was applied to the development of CD19CAR T cells.

The mbIL15 unit favors T memory stem cells (Tscm) formation. These cells are rare, but are extremely attractive for immunotherapies as they are the least differentiated memory T cell and can give rise to cytotoxic T cells. Ziopharm evaluated the mbIL15-CD19CAR T cells and found that they tested positive for the mbIL15 protein and Tscm biomarkers as well as expression of interferon-? and activation upon exposure to antigen-presenting cells. What’s more, the modified T cells remained viable for up to two years in culture without antigen stimulation. Yet, they did not demonstrate aberrant unrestricted proliferation and exhibited a normal karyotype and polyclonal T-cell receptor repertoires. Thus, these cells have the hallmarks of a Tscm.

The mbIL15-CD19CAR T cells displayed impressive in vivo functionality. They’ve shown no host toxicity or evidence of aberrant proliferation after long-term engraftment (125 days after infusion) preclinically. A test performed in a model of minimal residual disease or low tumor-associated antigen demonstrated the mbIL15-CD19CAR T cells rapidly eliminated leukemia cells by day 22, enabling 43% of the animals to survive to day 98. In contrast, 100% of the control mice died by day 34. A final test assessed the cells’ ability to eradicate an established malignancy and prevent disease recurrence. The results showed the mbIL15-CD19CAR T cells engrafted, mounted an antitumor response, and persisted after tumor clearance with no sign of relapse.

For an analyst ratings summary and ratings history on ZIOPHARM Oncology click here. For more ratings news on ZIOPHARM Oncology click here.



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