On September 21, 2015 Nektar Therapeutics (NASDAQ: NKTR) reported positive preclinical results for NKTR-214, a CD122-biased cytokine designed to preferentially stimulate the production and maintenance of tumor-killing T cells which are found naturally in the body (Press release, Nektar Therapeutics, SEP 21, 2015, View Source [SID:1234507510]). CD122, which is also known as the Interleukin-2 receptor beta subunit, is a key signaling receptor that is known to increase the proliferation of CD8-positive effector T cells, and these CD8-positive T cells comprise a key component of the tumor infiltrating lymphocytes that provide cell-mediated anti-tumor effects.1

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Results were presented this past Friday at the Inaugural CRI-CIMT-EATI-AACR Immunotherapy Conference in New York. NKTR-214 shows efficacy in multiple preclinical models as a single agent. Combination regimens with NKTR-214 and either anti-CTLA4 or anti-PD-1 checkpoint inhibitor therapies resulted in durable anti-tumor immunotherapeutic effects, which persisted long after the termination of dosing.

"We are very encouraged by these remarkable preclinical findings, which show an immune-educating vaccine-like effect with the combination and sequencing of NKTR-214 and checkpoint inhibition," said Stephen Doberstein, Ph.D., Senior Vice President and Chief Scientific Officer of Nektar Therapeutics. "This is the ultimate goal of immune-oncology and we look forward to initiating our planned Phase 1/2 clinical trial of NKTR-214 in the fourth quarter of 2015."

In a preclinical tumor re-challenge study presented, sequential dosing of anti-CTLA-4 followed by NKTR-214 resulted in durable and complete responses. At 142 days following the final dose, with no additional treatment, the complete responders demonstrated sustained resistance to multiple tumor re-challenges.

In highly-resistant established melanoma tumor models, data presented show that treatment with NKTR-214 resulted in a controlled, sustained and biased T-cell activating signal and a mean ratio of CD8-positive T cells to T-regulatory cells ratio of 450:1 in the tumor infiltrating lymphocytes.

NKTR-214 Preclinical Data Presentation
The presentation entitled, "Antitumor activity of NKTR-214, a CD122-biased immunostimulatory cytokine, combined with immune checkpoint blockade requires innate and adaptive immunity," which was presented at The Inaugural International Cancer Immunotherapy Conference (CIMT) (Free CIMT Whitepaper): Translating Science into Survival by CRI-CIMT-EATI-AACR can be accessed at View Source

About NKTR-214

NKTR-214 is a CD122-biased immune-stimulatory cytokine, which is designed to stimulate the patient’s own immune system to eliminate cancer cells. By biasing activation to the CD122 receptor, NKTR-214 enhances CD8-positive T cells (tumor-killing cells) in the tumor. In preclinical studies, a single dose of NKTR-214 resulted in an approximate 400-fold AUC exposure within the tumor compared with an equivalent dose of aldesleukin, an existing IL-2 therapy. This increase potentially enables, for the first time, an antibody-like dosing regimen for a cytokine.2 In dosing studies in non-human primates, there was no evidence of low blood pressure or vascular leak syndrome with NKTR-214 at predicted clinical therapeutic doses.3