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Aug 16, 2022
Nektar and Collaborators Announce Preclinical Publication of Data for NKTR-255 and its Observed Improvement of NK Cell Function in Multiple Myeloma

SAN FRANCISCO, Aug. 16, 2022 /PRNewswire/ -- Nektar Therapeutics (Nasdaq: NKTR) today announced the publication of preclinical data in Blood Advances, the open-access journal of the American Society of Hematology, highlighting the effects of NKTR-255, a novel polymer-conjugated human IL-15, on natural killer (NK) cell function and proliferation in multiple myeloma (MM).

"These findings published today in Blood Advances demonstrate the promising anti-tumor activity of IL-15 in engaging natural killer cell biology in indications with immunosuppressive tumor microenvironments as in multiple myeloma," said Nikhil C. Munshi, MD, Professor of Medicine at Harvard Medical School, Director of Basic and Correlative Science at the Jerome Lipper Multiple Myeloma Center at Dana-Farber Cancer Institute. "Among other immune cells, the NK cell expansion and improved function induced by NKTR-255 is contributing to more effective control of multiple myeloma tumor growth, raising a potential scope for synergism with other anti-MM therapies such as anti-CD38 antibodies."

The Dana-Farber team analyzed in vitro pharmacological properties of NKTR-255 in engaging the IL-15 pathway and stimulating NK cells against MM cells. The research also looked at the anti-tumor activity of combining NKTR-255 with the anti-CD38 antibody, daratumumab, in vitro and in vivo.

"The published data demonstrate that NKTR-255 not only enhances antitumor responses of human NK cells against MM target cells, but also increases ex vivo expression of NK activating receptors and adhesion molecules. Furthermore, studies in a humanized MM mouse model show that NKTR-255 enhances in vitro antibody-dependent cellular cytotoxicity (ADCC) of NK cells and synergizes with daratumumab to reduce MM cell growth," said Mariateresa Fulciniti, Ph.D., the senior author on this manuscript at Dana-Farber. These preclinical findings support Nektar's robust clinical development program for NKTR-255 and further evaluation of the novel immunotherapeutic approach in MM, alone or in combination with monoclonal antibodies or potentially with other immunomodulatory drugs.

Key findings are summarized below:

  • NKTR-255 enhances antitumor responses of myeloma derived human NK cells against MM target cells.
  • NKTR-255 enhances in vitro ADCC of NK cells and synergizes with daratumumab to reduce MM growth in humanized mouse model.
  • NKTR-255 increases ex vivo expression of NK activating receptors and adhesion molecules.
  • Augmenting NK cell number and functions shows effectiveness against MM cells in the context of their bone marrow milieu.

The full citation of this article can be accessed here.

About NKTR-255

NKTR-255 is a biologic that targets the IL-15 pathway in order to activate the body's innate and adaptive immunity. Through optimal engagement of the IL-15 receptor complex, NKTR-255 is designed to enhance functional NK cell populations and formation of long-term immunological memory, which may lead to sustained and durable anti-tumor immune response.

Preclinical findings suggest NKTR-255 has the potential to synergistically combine with antibody-dependent cellular cytotoxicity molecules as well as to enhance CAR-T therapies. Nektar has initiated a Phase 1 dose escalation and expansion clinical study of NKTR-255 in adults with relapsed or refractory non-Hodgkin lymphoma or multiple myeloma, as well as a Phase 1/2 clinical study of NKTR-255 in patients with relapsed or refractory head and neck squamous cell carcinoma or colorectal cancer. Nektar is also continuing its oncology clinical collaboration with Merck KGaA and Pfizer Inc. to evaluate the maintenance regimen of NKTR-255 in combination with avelumab, a PD-L1 inhibitor, in patients with locally advanced or metastatic urothelial carcinoma in the Phase II JAVELIN Bladder Medley study. Nektar is also currently designing a Nektar- sponsored Phase II study combining NKTR-255 with approved CAR-T cell therapies in diffuse large B-cell lymphoma, which it aims to initiate in the first quarter of 2023.

About Nektar Therapeutics

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

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements which can be identified by words such as: "will," "may," "demonstrate," "potential," "designed," "initiate," "aim" and similar references to future periods. Examples of forward-looking statements include, among others, statements we make regarding the therapeutic potential of, and future development plans for NKTR-255 and our other drug candidates in research programs, the prospects and plans for our collaborations with other companies, and the timing of the initiation of clinical studies and the data readouts for our drug candidates. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based only on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, anticipated events and trends, the economy and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict and many of which are outside of our control. Our actual results may differ materially from those indicated in the forward-looking statements. Therefore, you should not rely on any of these forward-looking statements. Important factors that could cause our actual results to differ materially from those indicated in the forward-looking statements include, among others: (i) our statements regarding the therapeutic potential of NKTR-255 and our other drug candidates are based on preclinical and clinical findings and observations and are subject to change as research and development continue; (ii) NKTR-255 and our other drug candidates are investigational agents and continued research and development for these drug candidates is subject to substantial risks, including negative safety and efficacy findings in ongoing clinical studies (notwithstanding positive findings in earlier preclinical and clinical studies); (iii) NKTR-255 and our other drug candidates are in various stages of clinical development and the risk of failure is high and can unexpectedly occur at any stage prior to regulatory approval; (iv) the timing of the commencement or end of clinical trials and the availability of clinical data may be delayed or unsuccessful due to challenges caused by the COVID-19 pandemic, regulatory delays, slower than anticipated patient enrollment, manufacturing challenges, changing standards of care, evolving regulatory requirements, clinical trial design, clinical outcomes, competitive factors, or delay or failure in ultimately obtaining regulatory approval in one or more important markets; (v) we may not achieve the expected costs savings we expect from our corporate restructuring and reorganization, (vi) patents may not issue from our patent applications for our drug candidates, patents that have issued may not be enforceable, or additional intellectual property licenses from third parties may be required; and (vii) certain other important risks and uncertainties set forth in our Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on August 5, 2022. Any forward-looking statement made by us in this press release is based only on information currently available to us and speaks only as of the date on which it is made. We undertake no obligation to update any forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments or otherwise.

Vivian Wu of Nektar Therapeutics

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