18 December 2019 - - US-based natural killer cell-based therapeutics company NantKwest Inc. (NASDAQ: NK) and immunotherapy company ImmunityBio have released results from their Phase 1b trial investigating a novel, first-in-human immunotherapy protocol consisting of NantKwest's off-the-shelf, antibody-targeted NK cells combined with ImmunityBio's IL-15 superagonist (N-803), low-dose metronomic chemoradiation therapy, adenoviral and yeast tumor-associated antigen vaccines (MUC1, brachyury, CEA) and a PD-L1 checkpoint inhibitor in patients with metastatic triple negative breast cancer who had relapsed after prior therapy, the companies said.

The results were presented at the 2019 San Antonio Breast Cancer Symposium (SABCS) on December 13, 2019, in San Antonio, Texas, in a poster titled "Safety and efficacy from first-in-human immunotherapy combining NK and T-cell activation with off-the-shelf, antibody-targeted CD16 NK cell line in patients with 2nd-line or greater metastatic triple-negative breast cancer."

This landmark study is the world's first trial to combine cellular therapy with checkpoint inhibitors and IL-15 cytokine stimulation, as well as with adenoviral vectors, all acting in concert to induce immune simulation of both NK cells and T cells.

Of 9 patients treated, efficacy results include a disease control rate of 78% (7/9 patients) and an overall response rate of 67% (6/9 patients).

Two out of 9 patients to date have ongoing complete responses with durations ranging from 8 to 11 months, with a 3rd patient demonstrating a partial response (near complete response) in the target lesion after initiation of targeted and endocrine therapy off-study.

To date, 7 patients are alive with durations of response ranging from 2 to 12 months with 4 patients remaining on study. Median progression-free survival rate is 13.7 months.

All patients were treated in an outpatient setting with treatment generally safe and well tolerated and no observed cytokine release syndrome.

No immune related SAEs were attributed to the immunotherapy investigational agents

All patients had at least 1 grade ≥ 3 TRAE, primarily chemotherapy-related neutropenia or anemia. Grade ≥ 3 haNK-related AEs, namely fever and fatigue, were observed in 2 patients.

Early data from peripheral blood analysis demonstrate clonal selection occurs with the immunotherapy regimen enabling targeted therapy tailored to patient specific mutations identified via next generation sequencing.

NantKwest (NASDAQ: NK) is an innovative, clinical-stage immunotherapy company focused on harnessing the power of the innate immune system to treat cancer and virally induced infectious diseases.

We are the leading producer of clinical dose forms of off-the-shelf Natural Killer cell therapies. Our activated NK cell platform is designed to destroy cancer and virally infected cells from the body.

The safety of our optimized, activated NK cells, as well as their activity against a broad range of cancers, have been tested in phase I clinical trials in Canada and Europe, as well as in multiple phase I and II clinical trials in the United States.

By leveraging an integrated and extensive genomics and transcriptomics discovery and development engine, together with a pipeline of multiple, clinical-stage, immuno-oncology programs, NantKwest's goal is to transform medicine by delivering living drugs in a bag and bringing novel NK cell-based therapies to routine clinical care.

NantKwest is a member of the NantWorks ecosystem of companies.

ImmunityBio is a privately held immunotherapy company with a broad portfolio of biological molecules, including an albumin-linked chemotherapeutic, peptides, fusion proteins, cytokines, monoclonal antibodies, adenovirus, and yeast vaccine therapies.

ImmunityBio's oncological goals are two-fold: To employ the company's broad portfolio of biological molecules to activate endogenous NK and CD8+ T cells, and to develop a T cell memory cancer vaccine to combat multiple tumor types without the use of high-dose chemotherapy.

The company's platform of technologies has enabled it to achieve one of the most comprehensive, late-stage clinical pipelines, addressing both the innate (activated macrophage and natural killer cell) and the adaptive immune system (dendritic, CD4 and CD8 killer T cells).

In 2020, ImmunityBio is planning to enroll patients in late-stage trials with molecules across multiple indications including triple negative breast cancer, lung cancer, head and neck cancer, Merkel cell carcinoma and glioblastoma.

In the field of infectious disease, ImmunityBio's goal is to develop vaccine therapies for the prevention and treatment of Influenza, Zika, Ebola, and HIV.