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From the Rare Disease TAUG From Stefan Konermann. | Rare Diseases Therapeutic Area User Guide, section 9.1, In Vivo Gene Therapy (Spinal Muscular Atrophy). Email from Stephen on 2023-09-01. |
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Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. An immunogenicity response may be wanted/desired or unwanted/undesired.
This example shows a Sars-CoV-2 vaccine study where the mechanism of delivery for the study vaccine antigenic component is based off of, and enabled by the viral vector technology. In this specific use-case, the transgene encoding the full-length, membrane-bound severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein is incorporated into a recombinant, replication-incompetent Human Adenovirus Type 26 (Ad26) Vector. The Sars-CoV-2 spike protein expressed by the transgene is the antigenic component of this vaccine. The "Ad26.COV2.S" study vaccine is then administered to patients. Neutralizing anti-vector antibodies (i.e. anti-Ad26 vector antibody) are closely monitored at baseline and post-study vaccine exposure visits. This is because the occurrence of the anti-vector antibodies could significantly hinder the Ad26 vector's ability to deliver the Sars-CoV-2 spike protein transgene to target cells, and consequently, either inhibits the planned vaccine therapy, or diminishes the efficacy of the study vaccine after administration.
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The example below shows a use-case of undesired, unwanted cellular immune responses toward a protein therapeutic delivered through the viral vector technology. In this case, cellular T-cell responses to both the viral vector and the therapeutic peptide (which is translated from the transgene delivered by the viral vector), are measured before and after study treatment. The T cell responses to both the vector and the theraptucis peptide are considered as "undesired/unwanted", which are indicated by the ISCAT = VECTOR-INDUCED IMMUNOGENICITY, and ISCAT = ANTIDRUG T CELL-MEDIATED IMMUNOGENICITY.
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