NKTR-255 monotherapy and in Combination with Rituxan© (rituximab) or Darzalex Faspro© (daratumumab)

INDICATION: Non-Hodgkin’s Lymphoma and Multiple Myeloma

Discovered and wholly owned by Nektar


Phase 2

NKTR-255 in combination with Erbitux© (cetuximab) in Solid Tumors

INDICATION: Head and Neck Cancer and Colorectal Cancer

Discovered and wholly owned by Nektar


Phase 2

About NKTR-255

NKTR-255 is an IL-15 receptor agonist designed to activate the IL-15 pathway and expand natural killer (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 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, which is rapidly cleared from the body and must be administered frequently and in high doses, limiting its utility due to toxicity and convenience of use.

One of the big challenges in treating cancer patients with targeted monoclonal antibodies is that the cancer patients have a deficiency in key effector cells like NK cells that are needed to work with the monoclonal antibodies.1,2 In nonclinical studies, NKTR‑255 exhibited anti-tumor activity and substantially enhanced in vivo proliferation and activation of NK cells to provide sustained cytotoxic function.3 In a preclinical lymphoma model where single agent daratumumab was ineffective, NKTR-255 treatment, in combination with daratumumab, increased NK cell numbers and activity in bone marrow tissue and enhanced ADCC-mediated tumor cell clearance in the bone marrow compartment.4

In oncology, NKTR-255 is being evaluated in combination with T cell redirection therapies, novel CAR-Ts, anti-HER2 antibodies and anti-CD20 antibodies via an ADCC-focused mechanism in preclinical models of liquid and solid tumors. NKTR-255 is also being evaluated in combination with anti-retroviral and immune modulator therapies through a research collaboration with Gilead.

About the Phase 1/2 Study of the Combination of NKTR-255 plus Cetuximab as a Salvage Therapy for the Treatment of Head and Neck Cancer and Metastatic Colorectal Cancer

This Phase 1/2 trial will test NKTR-255 in combination with cetuximab for two groups of patients. The first is patients with head and neck cancer who have progressed after treatment with platinum-based chemotherapy and checkpoint inhibitors. The second group is patients with metastatic colorectal cancer who have received two prior treatments for metastatic disease. The trial is expected to enroll up to 75 patients and will begin with a dose-finding portion for the combination, which will be expanded into dedicated cohorts for head and neck and colorectal cancer patients. For more information, please visit clinicaltrials.gov and search NCT04616196.

About the Phase 1 Study of NKTR-255 for the Treatment of Select Hematological Malignancies

The NKTR-255 Phase 1 study is an open-label, dose escalation and dose expansion study in patients with select hematological malignancies (relapsed or refractory NHL or MM). The dose escalation phase of the study will evaluate the safety and tolerability of NKTR-255 as monotherapy in approximately 40 patients in order to establish a recommended Phase 2 dose (RP2D) for NKTR-255. The dose expansion phase of the study will enroll in two separate cohorts: the first cohort will enroll patients with MM or NHL (relapsed salvage) to evaluate the NKTR-255 RP2D as a monotherapy and the second cohort will enroll patients with MM or NHL (relapsed/refractory salvage) to evaluate the NKTR-255 RP2D in combination with targeted antibodies, including anti-CD38 monoclonal antibody, daratumumab. The study will also evaluate pharmacokinetic and pharmacodynamic effects, anti-tumor activity and biomarker assessments. For more information, please visit clinicaltrials.gov and search NCT04136756.


1.    Messaoudene M., et al., (2017) Patient’s Natural Killer Cells in the Era of Targeted Therapies: Role for Tumor Killers. Front. Immunol. 8:683.

2.    Farnault, L., et al., Hematological Malignancies Escape from NK Cell Innate Immune Surveillance: Mechanisms and Therapeutic Implications. Clinical and Developmental Immunology Volume 2012, Article ID 421702, 8 pages

3.   Kick P, et al. Pre-clinical efficacy and tolerability of NKTR-255, a polymer-conjugated IL-15 for immune-oncology Journal for ImmunoTherapy of Cancer 2017 5(Suppl 2):87; P332.

4.    Miyazaki T., et al., NKTR-255, a polymer-conjugated IL-15 enhances anti-tumor NK cell responses and synergizes with monoclonal antibodies to provide long-term survival in human lymphoma model. In: Proceedings of the Annual Meeting of the AACR; 2019. Abstract 3265.

2021 Future Oncology

2021 Journal for ImmunoTherapy of Cancer

62nd American Society of Hematology (ASH) Annual Meeting & Exposition

2020 Society for Immunotherapy of Cancer (SITC) Annual Meeting

61st American Society of Hematology (ASH) Annual Meeting & Exposition, Orlando, FL

2019 Society for Immunotherapy of Cancer (SITC) Annual Meeting

4th Congress of European Hematology Association (EHA)

AACR 2019

2018 ASH 60th Annual Meeting

SITC 2018

2018 American Conference on Pharmacometrics (ACoP), San Diego, CA

CHI 3rd Annual NK Cell-Based Cancer Immunotherapy Conference, Boston, MA

CHI 2nd Annual Emerging Immuno-Oncology Targets Conference, Boston, MA

Society for Immunotherapy in Cancer (SITC) 32nd Annual Meeting, National Harbor, MD

2017 American Association for Cancer Research (AACR) Annual Meeting

2016 SITC Annual Meeting