ImmunityBio and NantKwest (NK) Announce FDA Authorization to Study hAd5 T-Cell COVID-19 Vaccine for Combination of Subcutaneous, Oral and Sublingual Boost to Induce T-Cell, Mucosal, and Antibody Immun

February 12, 2021 8:49 AM EST
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ImmunityBio, Inc., a privately-held immunotherapy company, and NantKwest, Inc. (NASDAQ: NK), a clinical-stage, natural killer cell-based therapeutics company, today announced they have received FDA authorization to expand Phase I testing of a bivalent hAd5 T-cell COVID-19 vaccine. The FDA authorized the expansion of a currently active multi-cohort trial of the subcutaneous version of the vaccine in order to study the addition of sublingual boosts. The FDA also authorized a second Phase I study that will examine the addition of an oral boost to the subcutaneous prime administration. As a result, the companies will enroll another 105 participants in the U.S. trials of their vaccine candidate, which is unique in targeting both the spike (S) and nucleocapsid (N) proteins of the SARS-CoV-2 virus.

The expectations of inducing protective immune responses in healthy volunteers – with this novel combination of an oral boost with a subcutaneous prime – are based on the positive findings reported in the NIH/BARDA-sponsored Non-Human Primate (NHP) study. This recent data showed that when administered with an oral boost, the bivalent vaccine resulted in potent stimulation of S- and N-specific T cells with potent antibody release from memory B cells following viral challenge. Additionally, activation of the full immune system by S and N proteins resulted in complete viral clearance of SARS-CoV-2 in lung and nasal passages following the challenge. On the basis of these findings, ImmunityBio has expanded the current Phase 1 study of subcutaneous prime with oral or sublingual boost to explore the potential of this second-generation vaccine to reduce disease and transmission of the virus.

The oral trial is a new study (NCT04732468) and the sublingual trial is the cohort C expansion to the Phase 1 subcutaneous trial (NCT04591717), which was initiated last Fall. Both oral and sublingual trials are anticipated to begin this month and will be conducted at two sites in California. Based on the findings of these trials involving over 100 participants, the optimal combination of route of administration and dose will be determined and entered into the Phase 2 / 3 design.

“The NHP study findings reinforce our hypothesis that a T-cell-based vaccine could be protective, not only in preventing mild, moderate, and severe disease, but also in potentially limiting transmission of the virus,” said Patrick Soon-Shiong, MD, Chairman and CEO of ImmunityBio. “We believe that the key to creating long-term immunity to the SARS-CoV-2 virus and overcoming the variants that are rapidly developing around the world is to create a vaccine that activates not only antibodies but also memory B and T cells to multiple antigens. Furthermore, room-temperature stable formulations for oral delivery have the potential to solve the cold-chain challenges of distribution and the ability to generate mucosal IgA antibody barriers to the virus in the upper respiratory tract where it first enters the body.”

One Vaccine, Two Trials, Three Routes of Immune Protection

The first two cohorts of the Phase Ib, open label, dose-ranging study (NCT04591717) of the vaccine received two different dose levels (.5 and 1ml). Participants received two subcutaneous injections 21 days apart. No grade three or four AEs and no SAEs were observed at either dose level and, in the intermediate (1ml) dose group, immunogenicity was observed as early as 14 days after the prime. An additional group of 40 subjects will be enrolled to evaluate safety, reactogenicity, and immunogenicity of the combination of hAd5 in four different cohorts receiving sublingual and subcutaneous formulations to select an optimal combination dose for future studies.

The second Phase 1b trial (NCT04732468) is designed to assess the safety, reactogenicity, and immunogenicity of the combination of hAd5 in oral capsule and subcutaneous formulations; and to select an optimal combination dose for future studies. Up to 65 subjects will be enrolled in the four-cohort study, which is anticipated to begin in Q1.

About the T-Cell-Based Vaccine Candidate

Developed by ImmunityBio and manufactured by NantKwest, this second generation hAd5 vectored vaccine is unique in targeting both spike (S) and nucleocapsid (N) SARS-CoV-2 proteins to generate B and T cell memory to these antigens and long-term immunity to the virus. Most of the COVID-19 vaccines approved by the FDA or in late-stage clinical trials deliver only the spike protein, which has already mutated several times. Another unique characteristic of the hAd5 design is its use of a second-generation hAd5 platform that was developed to elicit anti-SARS-CoV-2 immune responses even in Ad-immune individuals, meaning subjects can receive the vaccine multiple times, if necessary. The stimulation of anti-hAd5 immune responses is attenuated with the second-generation platform in comparison with the first-generation platforms, due to additional genetic deletions. The hAd5 room temperature-stable oral capsules were developed in partnership with UK-based biotechnology company iosBio.

Phase I trials have been initiated in the U.S. and recruitment is set to begin in February in Cape Town, South Africa for a trial (NCT04710303) of subcutaneous administration to be followed by additional trials using sublingual delivery and room temperature-stable oral capsules.

NantKwest Transaction

As previously announced, on December 21, 2020, ImmunityBio entered into an agreement to combine in a stock-for-stock transaction with NantKwest (NASDAQ: NK). The combination, which is expected to close in the first half of 2021, will create a leading immunotherapy and cell therapy company focused on oncology and infectious disease.

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