Press Release

SAN FRANCISCO, April 23, 2022 /PRNewswire/ -- Nektar Therapeutics (Nasdaq: NKTR) announced that collaborators from the Cairo Laboratory at New York Medical College today presented data from several preclinical studies demonstrating the potential of NKTR-255 to enhance the anti-tumor activities of different CAR-T therapies in a variety of cancer preclinical models. Presentations include an oral presentation by Wen Luo, Ph.D., assistant professor of pediatrics at NYMC, on in vivo and in vitro efficacy of NKTR-255 combined with anti-MCAM^a CAR^b modified Natural Killer (NK) cells in several tumor models, and a poster presentation by Yaya Chu, Ph.D., assistant professor of pediatrics at NYMC, presenting studies of NKTR-255 in combination with ex vivo expanded anti-CD19 CAR NK cells and anti-CD20 or anti-CD79 antibodies in models of Burkitt Lymphoma (BL).

"Our research builds on the body of knowledge for the role of an agent which activates the full IL-15 biology pathway in the field of cell therapy," said Mitchell S. Cairo, M.D., director of the Cairo Laboratory, chief of pediatric hematology, oncology and stem cell transplantation, director of the Children and Adolescent Cancer and Blood Diseases Center, associate chairman of the Department of Pediatrics and professor of pediatrics, medicine, pathology, microbiology and immunology and cell biology and anatomy at NYMC. "My lab's findings show that NKTR-255's ability to expand and proliferate NK cells resulted in the enhancement of the efficacy of two different CAR therapies in our preclinical models."

The oral presentation will be virtually live streamed on Saturday April 23^rd, 2022 at 3:00 PM MT and is accessible through the meeting organizer's website at https://www.astct.org/attend/tandem-meetings. These presentations are available for download at http://www.nektar.com/science/scientific-posters.

Key details and takeaways from the two collaborator presentations include:

Abstract 27: "Targeting Ewing sarcoma, Osteosarcoma and Neuroblastoma with Anti-MCAM Chimeric Antigen Receptor Modified Natural Killer Cells" Luo, W., et al.
Presentation Type: Oral Presentation
Presenting Author: Wen Luo, Ph.D.
Session: Oral Abstract - Session C - Immune and Gene Therapy
Virtual Live Stream of the presentation will begin at 3:00 PM MT on Saturday April 23^rd, 2022

• NKTR-255 enhances expression of NK cell-activating receptors, stimulates NK cell proliferation and sustains NK cell expansion
• NKTR-255 enhances anti-MCAM CAR NK cell cytotoxicity against Ewing sarcoma, osteosarcoma and neuroblastoma in vitro
• Anti-MCAM CAR NK alone or in combination with NKTR-255 significantly decrease lung metastasis and prolong animal survival in an Ewing sarcoma orthotopic mouse model

Abstract 201: "Optimizing Chimeric Antigen Receptor (CAR) Engineered NK Cell- Mediated Cytotoxicity Combined with anti-CD20 or anti-CD79 Therapeutic Antibodies and NKTR-255 in Burkitt Lymphoma (BL)" Chu, Y., et al.
Presentation Type: Poster

• NKTR-255 + obinutuzumab, a humanized type II anti-CD20 monoclonal antibody (mAb) glycoengineered to enhance Fc receptor affinity, significantly enhanced the in vitro cytotoxicity of anti-CD19 CAR NK compared to controls against multiple Burkitt lymphoma model (Raji) (p<0.0081) as well as release of perforin (p<0.05), IFN-g (p<0.001) and granzyme B (p<0.01)
• These results were further confirmed utilizing Raji-2R and Raji-4RH cells
• NKTR-255 + polatuzumab vedotin (PV), an anti-CD79 mAb glycoengineered to enhance Fc receptor affinity, significantly enhanced the in vitro cytotoxicity of anti-CD19 CAR NK cells compared to control groups such as expanded NK cells +NKTR-255 + PV against Raji (p<0.0001), Raji-2R (p<0.0003), and Raji-4RH (p<0.0311), as well as enhanced release of Interferon gamma (IFN-γ) and perforin

Posters will be on display Sunday, April 24, 2022 from 11:00 am to 7:15 pm; Monday, April 25, 2022 from 7:00 am to 7:00 pm; Tuesday, April 26, 2022 from 7:00 am to 12:00pm (all times MDT)

Poster Receptions are on Sunday, April 24, 2022 from 6:30 pm to 7:15 pm MDT

About NYMC
Founded in 1860, New York Medical College is one of the oldest and largest health sciences colleges in the country with nearly 1,500 students and 330 residents and clinical fellows, more than 2,600 faculty members and 23,200 living alumni. The College, which joined Touro University in 2011, is located in Westchester County, New York, and offers degrees from the School of Medicine, the Graduate School of Basic Medical Sciences, the School of Health Sciences and Practice, the Touro College of Dental Medicine at NYMC, and the Touro College School of Health Sciences' nursing program at NYMC. NYMC provides a wide variety of clinical training opportunities for students, residents, and practitioners. For more information, visit www.nymc.edu.

About NKTR-255
NKTR-255 is an investigational IL‐15 receptor agonist designed to boost the immune system's natural ability to fight cancer. NKTR-255 increases the proliferation and survival of cancer-killing natural killer (NK) cells and memory CD8+ T cells. NKTR-255 engages the entire IL-15 receptor complex (IL‐15Rα/IL‐15Rβγ) to enhance the formation of long-term immunological memory, which may lead to sustained antitumor immune response.

NKTR-255 is specifically engineered using Nektar's expertise in polymer chemistry to mimic the natural biological activity of the body's own IL-15, resulting in optimal activation of the IL-15 pathway. NKTR-255 is uniquely designed to overcome the challenges of recombinant IL-15, which has to be given in high doses due to rapid clearance from the body, limiting its utility due to toxicity and lack of convenience and use.

About Nektar
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 and Hyderabad, India. Further information about the company and its drug development programs and capabilities may be found online at http://www.nektar.com.

Cautionary Note Regarding Forward-Looking Statements
This press release contains forward-looking statements which can be identified by words such as: "will," "may," "design," "potential," "initiate," "plan," "advance" and similar references to future periods. Examples of forward-looking statements include, among others, statements we make regarding the future development plans and the timing of data readouts for bempegaldesleukin. 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 bempegaldesleukin are based on preclinical and clinical findings and observations and are subject to change as research and development continue; (ii) bempegaldesleukin is an investigational agent and continued research and development for this drug candidate 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) bempegaldesleukin remains in clinical development and the risk of clinical failure is high and can unexpectedly occur at any stage prior to regulatory approval; (iv) the timing of the end of clinical trials and the availability of clinical data may be delayed or unsuccessful due; (v) 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 (vi) certain other important risks and uncertainties set forth in our Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 28, 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.

Contact:

For Investors:
Vivian Wu of Nektar Therapeutics
628-895-0661

For Media:
Dan Budwick of 1AB
973-271-6085
dan@1abmedia.com

a)    MCAM: Melanoma Cell Adhesion Molecule
b)    CAR: Chimeric Antigen Receptor

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