Our Technology

The Need to do Better

The treatment of certain cancers has improved markedly over the past decade. Whereas many cancer treatments were historically limited to surgical removal, cytotoxic chemotherapy and/or radiation, recent advances target specific genetic changes in individual tumors or redirect the patient’s immune system, particularly T cells, to eliminate tumors to improve outcomes. Unfortunately, most patients do not respond to or relapse following treatment with these therapies.

While these therapies have advanced the treatment of cancer for some patients, many are still underserved, and therapies with improved clinical outcomes are still desperately needed.

The Promise of Viral Immunotherapies

The goal of immuno-oncology therapy is to harness an individual’s immune system and better enable it to identify, attack and kill tumor cells – and to form long lasting immunological memory against such tumors to prevent relapse.

We believe that the best way to significantly improve outcomes for cancer patients is to stimulate not only T cells, as has been the focus of approved immune checkpoint inhibitors and other recent advances in immuno-oncology, but also additional key immune cells within the innate and adaptive immune systems.

We believe viral immunotherapies are the most promising modality available today to activate multiple arms of the immune system and improve outcomes for cancer patients.

A Unique Therapeutic Approach

Viral immunotherapies have several properties that differentiate this class from other anti-tumor therapies and make them particularly attractive additions to today’s anti-cancer arsenal.


1. Selectively kill tumor cells via immunogenic cell death
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Viral immunotherapies can be designed to potentially selectively kill tumor cells while sparing healthy cells. Tumor cells are often more vulnerable to killing by viruses than healthy cells because tumors often have diminished antiviral defenses, creating an environment conducive to viral replication.


2. Create an inflammatory state that turns cold tumors hot
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When tumor cells die following viral replication, the cells release tumor-specific antigens and danger signals, which activate the innate immune system and promote inflammation within the tumor microenvironment. This, in turn, attracts both innate and adaptive immune cells to that area. Viral immunotherapies have been shown in the clinic to transform so-called cold tumors, with low numbers of infiltrated immune cells, into hot tumors, with high numbers of infiltrated immune cells, which are more likely to respond to checkpoint inhibitors.


3. Cause the release and presentation of a greater breadth of tumor-specific antigens
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The breadth of antigens that are presented by viral immunotherapy-induced tumor lysis, or tumor cell death, is far greater than that of other anti-tumor vaccine approaches that rely on single antigens or small collections of neoantigens. These antigens can then be presented by the recruited innate immune cells, such as macrophages and dendritic cells, to cells of the adaptive immune system to stimulate highly effective antigen-specific immunity.

By activating the adaptive immune response, anti-tumor T cells can then identify and attack all tumors in the body in addition to forming immunologic memory, which can provide patients with durable protective immunity.


4. Express transgenes within the tumor microenvironment that encode for immunostimulatory proteins
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Viruses can be engineered to carry transgenes directly into tumors where they can be expressed in high concentrations. These transgenes can encode immunostimulatory cytokines, immune checkpoint antibodies and other proteins that can further amplify anti-tumor immune responses. The ability of viral immunotherapies to deliver potent immunostimulatory factors directly to tumors with minimal systemic exposure represents a powerful method of amplifying the initial immune response by both stimulating the infiltrating immune cells and preventing their suppression in tumors, leading to improved outcomes for cancer patients.


At Oncorus, we are advancing two platforms, our Herpes Simplex Virus (HSV) Platform for intratumorally administered viral immunotherapies, and our selectively self-amplifying viral RNA (vRNA) Platform for intravenously (IV) administered viral immunotherapies. Across both platforms, and a resulting pipeline of viral immunotherapies, we are striving to treat a broad spectrum of cancers to bring the potential of this therapeutic class to as many patients as possible.

Our HSV Platform

Directly Targeting Tumors through Intratumoral Injection

Herpes Simplex Virus has emerged as the leading viral vector for immunotherapy. We have designed our proprietary Herpes Simplex Virus (HSV) Platform to develop improved viral immunotherapies that overcome the limitations of potency and the ability to stimulate anti-tumor immunity – both of which are challenges that have been encountered by previous viral immunotherapies and other immuno-oncology therapies.

We are using our HSV Platform to develop viral immunotherapies that can be directly administered into a tumor, resulting in high local concentrations of the therapeutic agent, as well as low systemic exposure to the therapy, which we believe could potentially limit systemic toxicities.

We intend to advance multiple therapies derived from our HSV Platform to address a spectrum of tumor types. We are developing our lead product candidate, ONCR-177, an intratumorally administered HSV viral immunotherapy for the treatment of multiple solid tumor cancers. We have additional HSV Platform-derived viral immunotherapy product candidates in earlier stage development, including ONCR-GBM to specifically target brain cancer, including glioblastoma multiforme.


Designed to Enhance Potency and Balance Safety

Our HSV Platform is designed to deliver next-generation viral immunotherapy impact by improving upon three basic characteristics of this therapeutic class to enhance potency without sacrificing safety.


Greater capacity to encode transgenes to drive systemic immunostimulatory activity
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Using our proprietary technology, we are developing HSV-based product candidates with the ability to carry greater numbers of transgenes than viral immunotherapies that are either currently approved or in clinical development. This expanded payload capacity:

  • Enables promotion of greater systemic immunostimulatory activity than could otherwise be achieved
  • Enables combined delivery of immunostimulatory agents directly to tumors including those that cannot safely be dosed in patients due to systemic toxicities, such as IL-12


Retention of full replication competency to enable high tumor-killing potency
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Using our proprietary HSV Platform, we are developing HSV-based viral immunotherapy product candidates that retain their full ability to replicate in tumor cells.

In contrast, current HSV-based viral immunotherapies that are either currently approved or in clinical development have introduced mutations which attenuate their replication competency in both normal and tumor tissues to limit toxicity. We believe this has the effect of lowering the potency of the virus in tumor cells and trading off potency for safety.


Orthogonal safety strategies to allow tumor-specific replication
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Our HSV Platform incorporates two highly innovative approaches to allow for tumor-specific replication, meaning we limit viral activity to tumor cells while sparing normal tissues.

  1. Use of microRNA, or miR, sequences. We insert gene regulatory elements known as miR target sequences within the genomes of viruses. The miRs complementary to these target sequences are primarily found only in normal tissues and not in tumor tissues.
  2. Mutate the HSV-1 protein, UL37. We have engineered a proprietary mutation in a HSV-1 protein, known as UL37, which eliminates the virus’ ability to transport, replicate and establish latency inside neurons.

About ONCR-177

Our lead HSV viral immunotherapy candidate, ONCR-177, currently in Phase 1 clinical study, is designed to mount a powerful, multidimensional attack on cancer; it induces immunogenic cancer cell death and ignites innate and adaptive immunity to drive a lasting and systemic anti-tumor response. In addition to its oncolytic activity, ONCR-177 is armed with five immunostimulatory transgenes (IL-12, CCL4, FLT3LG, anti-PD-1 and anti-CTLA-4).

View our Pipeline to learn more


Combining viral immunotherapies with an RNA-based approach to fight cancer

There has been a notable rise in the development and approval of RNA-based vaccines, most prominently for COVID-19, and therapeutics for certain rare diseases. However, to date, there are no approved RNA-based cancer therapies.

The IV administration of viral immunotherapies is an attractive approach for improving the standard of care for many oncology patients because it allows for all tumors in a patient, including micro-metastases that are sometimes difficult to detect and treat, to be treated directly.

In addition, it allows for potential treatment of certain tumors, such as those of the lung, that are less amenable to repeat intratumoral injection of anti-cancer therapies for safety and feasibility reasons.

To date, however, the therapeutic benefit of viral immunotherapy has been limited to intratumoral administration, restricting the application of this modality. In addition, past investigational programs that utilized IV-administered natural viral immunotherapies faced the challenge of neutralizing antibodies which is efficacy limiting in our preclinical models.

Our proprietary IV-delivered vRNA Immunotherapy Platform involves a novel, highly innovative combination of RNA- and viral immunotherapy-based modalities, enabling the potential to deliver a new pillar in cancer therapy.



Our pioneering IV-administered vRNA approach involves encapsulating the RNA genomes of viruses known to kill cancer cells (i.e., viral immunotherapies) in a lipid (i.e., fat) nanoparticle (or LNP), creating a vRNA/LNP immunotherapy.

This LNP delivery strategy, which is intended to be less immunogenic than a natural viral capsid, is designed to overcome the challenges caused by neutralizing antibodies that have limited the efficacy of previous industry efforts to administer viruses intravenously to treat tumors.

Once inside the tumor cells, and as is the case with other viral immunotherapies, these genomes replicate and generate a burst of infectious virions that then spread locally and infect and kill adjacent tumor cells.





Our lead vRNA immunotherapy programs, ONCR-021 and ONCR-788, are based on coxsackievirus A21 (CVA21) and Seneca Valley Virus (SVV), respectively. Both of these viruses have demonstrated acceptable safety and tolerability when virions have been administered intravenously in early clinical trials conducted by others, but where efficacy was likely limited by the subsequent development of neutralizing antibodies.

ONCR-021, ONCR-788 and any future viral immunotherapy product candidates to be developed from our vRNA Platform will utilize shared formulation, regulatory and manufacturing strategies, allowing us to be more efficient in the development of subsequent product candidates.

View our Pipeline to learn more

Oncorus Publications & Presentations

Development of ONCR-788, a synthetic oncolytic virus based on Seneca Valley Virus for the treatment of neuroendocrine tumors

American Association for Cancer Research (AACR), April 8-13, 2022

Edward M. Kennedy, Agnieszka Denslow, Jacqueline Hewett, Lingxin Kong, Ana De Almeida, Jeffrey Bryant, Jennifer S. Lee, Judy Jacques, Sonia Feau, Melissa Hayes, Elizabeth L. McMichael, Daniel Wambua, Jacob Spinale, Matthew Scott, Jessica Deterling, Sean Essex, Jason Auer, Brian B. Haines, Mitchel H. Finer, Ted Ashburn, Christophe Quéva, and Lorena Lerner

ONCR-021 as a systemic intravenous synthetic RNA virus immunotherapy for the repeat treatment of cancer

American Association for Cancer Research (AACR), April 8-13, 2022

Jeffrey Bryant, Agnieszka Denslow, Jacqueline Hewett, Chris Dupont, Lingxin Kong, Ana De Almeida, Irene Rodriguez Sanchez, Jennifer S. Lee, Judy Jacques, Sonia Feau, Daniel Wambua, Adrienne Yanez, Pamela Wang, Jessica Deterling, Matthew Scott, Jason Auer, Brian B. Haines, Christophe Quéva, Lorena Lerner, and Edward M. Kennedy

Initial results of a Phase 1 study of intratumoral ONCR-177, an oncolytic herpes-simplex virus-1 expressing five immunomodulatory transgenes, in subjects with advanced injectable tumors

Society for Immunotherapy of Cancer (SITC), November 12-14, 2021

Jong Chul Park, Hatem Soliman, Gerald Falchook, Taofeek K. Owonikoko, Anna Spreafico, Erminia Massarelli, Meredith McKean,  Laura QM Chow, Patrick A. Ott, Robert Wesolowski, Christos Fountzilas, Corey Whalen, Adrienne G. Yanez, Christopher D. Dupont, Julia Auer, Tooba Cheema, John Goldberg, Ted T.  Ashburn and Igor Puzanov

Synthetic Oncolytic Virus Therapy for Repeat Systemic Treatment of Cancer

International Oncolytic Virus Conference (IOVC), November 5 - 7, 2021

ONCR-GBM: A Novel, Armed Oncolytic HSV-1 Vector Engineered for Efficacy and Safety in Glioblastoma

International Oncolytic Virus Conference (IOVC), November 5 - 7, 2021

Craig A. Strathdee, Federico Giovannoni, Peter Grzesik, Terry Farkaly, Michael Floyd, Lingxin Kong, Sanmit Adhikari, Judith Jacques, Agnieszka Denslow, Edward M. Kennedy, Brian B. Haines, Lorena Lerner, Christophe Quéva, and Francisco J. Quintana

ONCR-177, an oncolytic HSV-1 designed to potently activate systemic antitumor immunity

Cancer Immunology Research, December 22, 2020

Brian B Haines, Agnieszka Denslow, Peter Grzesik, Jennifer S Lee, Terry Farkaly, Jacqueline Hewett, Daniel Wambua, Lingxin Kong, Prajna Behera, Judith Jacques, Caitlin Goshert, Michael Ball, Allison Colthart, Mitchel H. Finer, Melissa W Hayes, Sonia Feau, Edward M. Kennedy, Lorena Lerner and Christophe Quéva. ONCR-177, an Oncolytic HSV-1 Designed to Potently Activate Systemic Antitumor Immunity. Cancer Immunology Research. December 22, 2020; DOI: 10.1158/2326-6066.CIR-20-0609

Design of an interferon-resistant oncolytic HSV-1 incorporating redundant safety modalities for improved tolerability

Molecular Therapy: Oncolytics, August 8, 2020

Edward M. Kennedy, Terry Farkaly, Peter Grzesik, Jennifer Lee, Agnieszka Denslow, Jacqueline Hewett, Jeffrey Bryant, Prajna Behara, Caitlin Goshert, Daniel Wambua, Ana De Almeida, Judith Jacques, Damian Deavall, James B. Rottman, Joseph C. Glorioso, Mitchell H. Finer, Brian B. Haines, Christophe Quéva, and Lorena Lerner.  Molecular Therapy: Oncolytics, Vol 18, pages 476-490.; https://doi.org/10.1016/j.omto.2020.08.004

mONCR-177 oncolytic virotherapy stimulates anti-tumor response

ACCR Annual Meeting Virtual Meeting II, June 22 - 24, 2020

Development of ONCR-177, an armed oncolytic HSV-1 designed for potent and systemic stimulation of antitumor immunity

6th Annual Immuno-Oncology 360°, New York, New York, February 26 – 28, 2020

Design of ONCR-177 base vector, a next generation oncolytic herpes simplex virus type-1, optimized for robust oncolysis, transgene expression and tumor-selective replication

AACR Annual Meeting, Atlanta, Georgia, March 29 – April 3, 2019

Development of ONCR-148, a miR-attenuated oncolytic HSV-1 designed to potently activate antitumor T cell response

AACR Annual Meeting, Atlanta, Georgie, March 29 – April 3, 2019

Development of ONCR-NEP, a lipid nanoparticle delivered oncolytic virus capable of robust in situ amplification resulting in tumor lysis and regression

AACR Annual Meeting, Atlanta, Georgia, March 29 – April 3, 2019

Arming oHSV with ULBP3 drives abscopal immunity in lymphocyte-depleted glioblastoma

JCI Insight, July 11, 2019

Hans-Georg Wirsching, Huajia Zhang, Frank Szulzewsky, Sonali Arora, Paola Grandi, Patrick J. Cimino, Nduka Amankulor, Jean S. Campbell, Lisa McFerrin, Siobhan S. Pattwell, Chibawanye Ene, Alexandra Hicks, Michael Ball, James Yan, Jenny Zhang, Debrah Kumasaka, Robert H. Pierce, Michael Weller, Mitchell Finer, Christophe Quéva, Joseph C. Glorioso, A. McGarry Houghton, and Eric C. Holland.  Arming oHSV with ULBP3 drives abscopal immunity in lymphocyte-depleted glioblastoma. JCI Insight. 2019;4(13):e128217.  https://doi.org/10.1172/jci.insight.128217


Cooperation of oncolytic virotherapy with with VEGF-neutralizing antibody treatment in IDH wildtype glioblastoma depends on MMP9

Neuro-Oncology, December 2019

Hans-Georg Wirsching, Sonali Arora, Huajia Zhang, Frank Szulzewsky, Patrick J Cimino, Christophe Quéva, A McGarry Houghton, Joseph C Glorioso, Michael Weller, Eric C Holland, Cooperation of oncolytic virotherapy with VEGF-neutralizing antibody treatment in IDH wildtype glioblastoma depends on MMP9, Neuro-Oncology, Volume 21, Issue 12, December 2019, Pages 1607–1609, https://doi.org/10.1093/neuonc/noz145

Additional Resources

Optimizing oncolytic virotherapy in cancer treatment

Harrington, K., Freeman, D.J., Kelly, B. et al. Optimizing oncolytic virotherapy in cancer treatment. Nat Rev Drug Discov 18, 689–706 (2019). https://doi.org/10.1038/s41573-019-0029-0

Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy

Ribas, A., Dummer, R., et al. Oncolytic Virotherapy Promotes Intratumoral T Cell Infiltration and Improves Anti-PD-1 Immunotherapy. Cell 170, 1109-1119 (2017). https://www.cell.com/fulltext/S0092-8674(17)30952-2