Nektar Therapeutics Announces Dosing of First Patients in Phase 1/2 Study of its IL-15 Agonist, NKTR-255, in Combination with Cetuximab in Patients with Head and Neck Squamous Cell Carcinoma or Colorectal Cancer

SAN FRANCISCO, CA, USA I December 15, 2020 I Nektar Therapeutics (NASDAQ:NKTR) today announced that the first patient has been dosed in the Phase 1/2 trial of NKTR-255, Nektar's investigational IL-15 pathway agonist, in patients with relapsed or refractory (R/R) head and neck squamous cell carcinoma (HNSCC) or colorectal cancer (CRC) at the START Center for Cancer Care in San Antonio, TX. The study is evaluating NKTR-255 plus cetuximab in up to 80 patients at approximately 15 investigator sites in the United States and European Union.

NKTR-255 is designed to activate the IL-15 pathway and expand Natural Killer (NK) cells as well as promote the survival and expansion of CD8+ T cells without inducing suppressive regulatory T cells. Cetuximab is a monoclonal antibody against epidermal growth factor receptor (EGFR) and is approved for the treatment of advanced HNSCC and CRC.

"An NK-cell agent such as NKTR-255 is a perfect and unique complement to monoclonal antibody therapies which induce antibody-dependent cellular cytotoxicity," said Wei Lin, MD, Head of Development at Nektar. "Our body of preclinical and clinical data for NKTR-255 demonstrates that this novel agent not only induces NK cell proliferation but also enhances their cytotoxic immune effector function. With this new Phase 1/2 study in HNSCC and CRC, we are excited to expand our NKTR-255 development program beyond the hematological setting into solid tumors."

Nektar recently presented the first clinical data for NKTR-255 at the most recent 2020 Society for Immunotherapy in Cancer (SITC) Annual Meeting in November. The data demonstrated that NKTR-255 was well tolerated and biologically active, and treatment resulted in consistent expansion of lymphocytes, with durable and sustained increases in NK and CD8+ T cells in a highly refractory population of patients with multiple myeloma (MM) and non-Hodgkin lymphoma (NHL).

The new Phase 1b/2 study will test the combination of NKTR-255 with cetuximab in two groups of patients. One group will consist of R/R head and neck cancer patients who have progressed after treatment with platinum-based chemotherapy and a checkpoint inhibitor. The second group will include patients with metastatic colorectal cancer who have received two prior treatments for metastatic disease. The trial will begin with a dose-finding portion for the combination, which will then be expanded into dedicated cohorts for head and neck and colorectal cancer patients.

About NKTR-255

NKTR-255 is an investigational IL-15 receptor agonist designed to activate the IL-15 pathway and expand NK cells and promote the survival and expansion of memory CD8+ T cells without inducing suppressive regulatory T cells. Through optimal engagement of the IL-15Rα/IL-2Rβγ receptor complex, NKTR-255 enhances functional NK cell population and formation of long-term immunological memory, which may lead to sustained anti-tumor immune response. NKTR-255 is uniquely designed to overcome the challenges of recombinant IL-15 and other IL-15 agonists, which are rapidly cleared from the body and have shown diminishing response to successive doses.1 NKTR-255 is wholly-owned by Nektar.

About Nektar

Nektar Therapeutics is a biopharmaceutical company with a robust, wholly owned R&D pipeline of investigational medicines in oncology, immunology, and virology as well as a portfolio of approved partnered medicines. Nektar is headquartered in San Francisco, California, with additional operations in Huntsville, Alabama and Hyderabad, India. Further information about the company and its drug development programs and capabilities may be found online at

1.  Blood 2018 Jun 7;131(23):2515-2527

SOURCE: Nektar Therapeutics

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