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Growth, Purification, and Titration of Oncolytic Herpes Simplex Virus
Published on: May 13, 2021
Biosafety and biohazard considerations of HSV-1-based oncolytic viral immunotherapy
Elizabeth Robilotti1, Nathalie C Zeitouni2, Marlana Orloff3
1Hospital for Special Surgery, New York, NY, United States.
Abstract:
Oncolytic viral immunotherapies are agents which can directly kill tumor cells and activate an immune response. Oncolytic viruses (OVs) range from native/unmodified viruses to genetically modified, attenuated viruses with the capacity to preferentially replicate in and kill tumors, leaving normal tissue unharmed. Talimogene laherparepvec (T-VEC) is the only OV approved for patient use in the United States; however, during the last 20 years, there have been a substantial number of clinical trials using OV immunotherapies across a broad range of cancers. Like T-VEC, many OV immunotherapies in clinical development are based on the herpes simplex virus type 1 (HSV-1), with genetic modifications for tumor selectivity, safety, and immunogenicity. Despite these modifications, HSV-1 OV immunotherapies are often treated with the same biosafety guidelines as the wild-type virus, potentially leading to reduced patient access and logistical hurdles for treatment centers, including community treatment centers and small group or private practices, and healthcare workers. Despite the lack of real-world evidence documenting possible transmission to close contacts, and in the setting of shedding and biodistribution analyses for T-VEC demonstrating limited infectivity and low risk of spread to healthcare workers, barriers to treatment with OV immunotherapies remain. With comprehensive information and educational programs, our hope is that updated biosafety guidance on OV immunotherapies will reduce logistical hurdles to ensure that patients have access to these innovative and potentially life-saving medicines across treatment settings. This work reviews a comprehensive collection of data in conjunction with the opinions of the authors based on their clinical experience to provide the suggested framework and key considerations for implementing biosafety protocols for OV immunotherapies, namely T-VEC, the only approved agent to date.
Insights
Oncolytic viruses (OVs) are innovative cancer therapies. Updated biosafety guidelines for OV immunotherapies, like Talimogene laherparepvec (T-VEC), can reduce treatment barriers and improve patient access to these life-saving treatments.
Area of Science:
- Oncolytic virotherapy
- Cancer immunotherapy
- Viral oncology
Background:
- Oncolytic viruses (OVs) are engineered or naturally occurring viruses that selectively infect and kill cancer cells while stimulating an anti-tumor immune response.
- Talimogene laherparepvec (T-VEC) is the sole FDA-approved oncolytic virus in the United States, primarily used in melanoma treatment.
- Numerous clinical trials have explored OV immunotherapies for various cancers, with many based on modified herpes simplex virus type 1 (HSV-1).
Purpose of the Study:
- To review existing data and clinical experience regarding biosafety protocols for oncolytic virus (OV) immunotherapies.
- To propose a framework and key considerations for implementing biosafety protocols for OV therapies, focusing on T-VEC.
- To address and reduce logistical hurdles associated with OV immunotherapy administration in diverse healthcare settings.
Main Methods:
- Comprehensive review of available data on OV immunotherapies, including T-VEC.
- Analysis of clinical experience and expert opinions on biosafety practices.
- Evaluation of shedding and biodistribution data for T-VEC to assess transmission risks.
Main Results:
- Despite modifications for tumor selectivity and safety, HSV-1 based OVs often face stringent biosafety guidelines similar to wild-type viruses.
- Existing data, including T-VEC shedding and biodistribution studies, suggest limited infectivity and low risk of transmission to healthcare workers and close contacts.
- Persistent barriers to OV immunotherapy access remain due to perceived risks and logistical challenges in treatment centers.
Conclusions:
- Updated and evidence-based biosafety guidance is crucial for facilitating wider adoption of OV immunotherapies.
- Streamlining biosafety protocols can overcome logistical hurdles, ensuring broader patient access to T-VEC and other OV agents.
- Educational programs and comprehensive information can enhance healthcare provider confidence and support the implementation of OV immunotherapies across various clinical settings.
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