Vaccinex, Inc. (Nasdaq: VCNX) is a publicly traded clinical-stage biotechnology company engaged in the discovery and development of targeted biotherapeutics to treat serious diseases with unmet medical needs, including neurodegenerative diseases, cancer and autoimmune disorders.


Pepinemab (VX15/2503)

VX15/2503 (USAN Council approved name "pepinemab") is a humanized monoclonal antibody that binds and blocks the signaling activity of SEMA4D. SEMA4D is an extracellular signaling molecule that regulates the migration of immune and inflammatory cells to sites of injury, cancer or infection. Pepinemab (VX15/2503)'s mechanisms of action block the SEMA4D signal and activate innate physiological mechanisms to respond to tumors or tissue injury. We have shown in preclinical studies that the biological activities associated with an antibody blockade of SEMA4D can promote immune cell infiltration into tumors and the repair or prevention of neurological damage in neuroinflammatory and neurodegenerative diseases.

Note: Pepinemab (VX15/2503) is an investigational drug currently in clinical studies. It has not been demonstrated to be safe and effective for any disease indication. There is no guarantee that pepinemab (VX15/2503) will be approved for the treatment of any disease by the U.S. Food and Drug Administration or by any other health authority worldwide.


Vaccinex discovered and developed an immune-modulating, anti-semaphorin 4D (SEMA4D) antibody, pepinemab (VX15/2503) that was shown in preclinical studies to regulate the infiltration of immune cells into the tumor microenvironment, especially when combined with checkpoint inhibitor and other immunomodulatory therapies. Specifically, anti-SEMA4D induces an increase in tumor-specific cytotoxic T cells and a change in the balance of tumoricidal and regulatory macrophage toward a pro-inflammatory, anti-tumorigenic response.

Learn more about Pepinemab (VX15/2503) for Immuno-Oncology


Huntington’s disease (HD) is a devastating neurodegenerative disease that results in uncontrolled movements and debilitating cognitive and behavioral changes. Astrocytes and microglia are key components of the brain that support neurons and shape neural networks by regulating formation and maintenance of synapses. Under conditions of physiological stress or injury, astrocytes and microglia transition from their normal function to an inflammatory state that can trigger or exacerbate degenerative processes in this and other neurological disorders. While it is widely believed that neuronal loss is irreversible, we believe other important elements that govern neurological activity, in particular glial cells and synapses, may be replenished or repaired with significant impact on disease progression. Vaccinex is investigating the ability of pepinemab (VX15/2503) to preserve normal glial cell function and to protect neurons from degeneration so as to modify the effects or delay the onset of this genetically determined disease by blocking the inflammatory response of astrocytes and microglia.

Learn more about Pepinemab (VX15/2503) for Neurology


Vaccinex has developed a fusion protein technology to enable the direct incorporation of multipass membrane proteins such as GPCRs and ion channels into the membrane of a mammalian virus. This method recovers the protein of interest naturally imbedded in the mammalian cell derived membrane, and because the whole virus is used, does not require any detergents or refolding in order to generate properly folded protein. This technology can be applied to multiple different cell types in order to maximize protein expression and to provide for any necessary chaperones. Antigen expressing virus can be readily purified and used for antibody selection using either in vitro display or immunization methods. 

We use a similar fusion protein strategy with our antibody discovery platform that enables efficient mammalian cell based expression of a library of human antibodies in full length IgG format on the surface of both the mammalian virus and cell. The platform combines the advantages of virus panning and cell sorting into one seamless selection process. This technology enables the rapid selection of >1010 antibody combinations and thus selection of high affinity leads with varied frameworks that recognize multiple epitopes. The selected antibodies are ideally suited for development because they have already passed mammalian cell quality control during the selection process.

ActivMAb technology offers:

  • an innovative and efficient method for selecting antibodies against multi-pass membrane proteins, an important class of pharmacological targets.
  • rapid generation of high affinity, full-length, human monoclonal antibodies synthesized and naturally modified in mammalian cells,
  • evolution/optimization of protein expression by mutagenesis and selection for desired variants in a fully mammalian cell system.

Learn more about ActivMAb®