By John Vandermosten, CFA

NASDAQ:HTBX

READ THE FULL HTBX RESEARCH REPORT

Since Our Last Update

Since our last update, Heat Biologics, Inc. (NASDAQ:HTBX) has announced several major developments including the unveiling of Heat's RapidVax novel cellular vaccine platform, a planned acquisition of Elusys Therapeutics, and new PTX-35 preclinical data in organ transplantation. Heat also looks forward to filing for its End-of-Phase II meeting with the FDA in 1Q:22, following its Phase II trial of HS-110 (gp96 + CTA¹) in NSCLC.²

RapidVax Unveiled

On November 30, 2021, Heat unveiled its RapidVax platform at the 2021 World Antiviral Congress. The RapidVax platform is designed for ‘plug and play' programming, to enable fast vaccine response against emerging infectious agents and viral variants. The poster presentation unveiling RapidVax can be accessed here. The unveiling came shortly after the World Health Organization classified Omicron as a new variant on November 26 and the US classified it as a Variant of Concern on November 30^th. RapidVax leverages the intrinsic flexibility and efficacy of Heat's gp96 platform, transforming it into a programmable vaccine that can be stockpiled in un-programmed form and then primed as threats emerge. Heat reports a three-month turnaround from the identification of the pathogen, to its sequencing, and then transfection into ready-made RapidVax. Transfection is via a plasmid encoding an antigen that gp96 can present to the host's immune system targeting and activating the host's T cells via gp96/APC³ and O40XL. Similar to Heat's existing gp96 cell lines, the candidate induces mucosal immunity and long-term memory response while avoiding anti-vector immunity, viral activation and permanent genetic modification of the host genome.

Heat has demonstrated early efficacy of RapidVax prototypes against simian immunodeficiency virus, and induction of Zika-specific and malaria-specific CD8+ T cell response in NHP⁵ and murine models, respectively. Likewise, a SARS-CoV-2 prototype was constructed programming RapidVax with SARS-CoV-2 spike protein plasmids. The murine model showed statistically differentiable CD8+ T cell response against both subunit epitopes in the bronchial alveolar fluid and spleen versus PBS control. There was a statistically significant increase in % of CD8+ and CD4+ T cells in the lung secreting TNFα and IL-2, and % of CD4+ T cells secreting IFNγ in the lungs in RapidVax vaccinated mice. Statistically significant induction of CD8+ T cells in the lung and spleen, and of effector memory and tissue resident memory CD8+ T cell in the lung.

Planned Acquisition of Elusys Therapeutics

On December 21, 2021, Heat announced that it had executed a definitive merger agreement to acquire Elusys Therapeutics. Elusys is a commercial-stage biodefense company and manufacturer of obiltoxaximab (ANTHIM), a treatment for anthrax inhalation that is approved in the US, Canada, Europe and the UK. The acquisition is expected to close in 1Q:22. Once acquired, Elusys will become a wholly owned subsidiary of Heat, expanding Heat's infectious disease portfolio. To date, Elusys has been awarded over $350 million in research and development contracts and procurement orders. Elusys has been supplying ANTHIM to the US Strategic National Stockpile through an ongoing, multi-year partnership. ANTHIM is a monoclonal antibody that binds to the protective antigen component of anthrax toxin, thereby preventing the entry of the toxin into vulnerable cells.

New PTX-35 Preclinical Data

Heat announced on January 12, 2022, that new preclinical data for PTX-35 had been accepted for publication in the American Journal of Transplantation, submitted under the brief title "Tumor necrosis factor receptor superfamily member 25 (TNFRSF25) agonists in islet transplantation: Endogenous in vivo regulatory T cell expansion promotes prolonged allograft survival." PTX-35, a T cell costimulator antibody targeting TNFRSF25 (Death Receptor 3), was investigated for its ability to promote endogenous in vivo Treg expansion, in contrast to current approaches that rely on complex ex vivo protocols. Endogenous Treg expansion is of interest because Tregs modulate alloimmune response, such as in the case of organ transplant, and stimulation of TNFRSF25 has the potential to prolong graft survival. Mice were treated with a single dose of 4C12/mPTX-35 or IgG control. After chemically inducing diabetes, four days later the mice received beta-cell islet transplantation with allograft tissue. Glycemia was assessed three times a week until rejection or endpoint. Results showed that TNFRSF25 antibody treated mice had significantly prolonged islet graft survival compared with controls (p < .001). Furthermore, Treg infiltration was observed in long-term surviving grafts.

Events and Milestones

➢ Continued enrollment in PTX-35 trial - 2021/2022

➢ Acquisition of Elusys Therapeutics - 1Q:22

➢ End of Phase II meeting with the FDA for HS-110 - 2022 (Filing 1Q:22)

➢ Completion of Scorpion facility construction - 1H:22

Summary

Since our last update, Heat has had recent developments including the unveiling of Heat's RapidVax novel cellular vaccine platform, plans to acquire of Elusys Therapeutics, and new PTX-35 preclinical data in organ transplantation. Heat looks forward to filing for its End-of-Phase II meeting with the FDA in 1Q:22 following its Phase II trial of HS-110 (gp96 + CTA⁸) in NSCLC⁹.

Heat has continued to advance its portfolio of cancer therapies and expand its presence in biodefense. The Scorpion facility will enhance Heat's ability to conduct process development, manufacturing and testing and provide additional avenues for revenue generation. Several milestones related to continuation of the PTX-35 and HS-110 programs are expected in the near future. We anticipate that the next value driver for Heat Biologics will be further clarity on design and structure of the anticipated registrational trial for HS-110 following and end of Phase II meeting with the FDA. With a strong balance sheet, success in its clinical development and sufficient cash to support its initiatives, we continue to be advocates of Heat Biologics.

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1. Cancer Testis Antigens

2. Non small-cell lung cancer

3. Antigen Presenting Cell, cells that present antigens to T cells, thereby activating and targeting them

4. Source: Heat Biologics January 2022 Corporate Presentation. Anthim is pending the planned acquisition of Elusys.

5. Non-human primate

6. Source: Heat Biologics January 2022 Corporate Presentation. Anthim is pending the planned acquisition of Elusys.

7. Source: Heat Biologics January 2022 Corporate Presentation. Anthim is pending the planned acquisition of Elusys.

8. Cancer Testis Antigens

9. Non small-cell lung cancer