Generation of a Novel Mesothelin-Targeted Oncolytic Herpes Virus and Implemented Strategies for Manufacturing

Abstract

Background: HER2-based retargeted viruses are in advanced phases of preclinical development of breast cancer models. Mesothelin (MSLN) is a cell-surface tumor antigen expressed in different subtypes of breast and non-breast cancer. Its recent identification as a marker of some triple-negative breast tumors renders it an attractive target, presently investigated in clinical trials employing antibody drug conjugates and CAR-T cells. The availability of MSLN-retargeted oncolytic viruses may complement the current immunotherapeutic panel of biological drugs against HER2-negative breast and non-breast tumors. Methods: A fully virulent, tumor-targeted oncolytic Herpes simplex virus-1 (MSLN-THV) with a selectivity for mesothelin-expressing cancer cells was generated. Recombineering technology was used to replace an essential moiety of the viral glycoprotein D with antibody fragments derived from clinically validated MSLN monoclonal antibodies, and to allow IL12 cargo expression in infected cells. Panels of breast and female reproductive system cell lines were used to verify the oncolytic potential of the viral constructs. A platform for production of the retargeted viruses was developed in HEK 293 cells, providing stable expression of a suitable chimeric receptor. Results: We demonstrated the selectivity of viral infection and cytotoxicity by MSLN-retargeted viruses in a panel of mesothelin-positive cancer cells, originating from breast and female reproductive system tumors. We also developed a second-generation oncolytic MSLN-THV, encoding IL12, to enhance the immunotherapeutic potential of the viral backbone. A non-tumor cell line expressing a chimeric MSLN/Nectin-1 receptor, de-sensitized from antiviral responses by genetic inactivation of the Stimulator of Interferon Genes (STING)-dependent pathway was engineered, to optimize viral yields. Conclusions: Our proof-of-concept study proposes MSLN-retargeted herpesviruses as potential cancer immunotherapeutics for assessments in preclinical models of MSLN-positive tumors, complementing the available panel of oncolytic viruses to HER2-negative breast tumors.

Novel Combinations of Human Immunomodulatory mAbs Lacking Cardiotoxic Effects for Therapy of TNBC

“…Since mAb-based monotherapy can only achieve about 10% response, several preclinical and clinical trials are currently focusing on combinatorial treatments with the aim to achieve higher therapeutic index with respect to monotherapy [ 16 , 17 ]. To date, combinatorial approaches of immunomodulatory mAbs with chemotherapy, radiotherapy, and other therapies are under evaluation also in TNBC, such as: trials based on the use of the anti-PD-1 mAb pembrolizumab in combination with the anti-microtubule agent eribulin [ 18 ], or with three different chemotherapy regimens comprising either nab-paclitaxel, paclitaxel or carboplatin plus gemcitabine [ 19 ], or in combination with niraparib (a selective inhibitor of PARP1/2 used in TOPACIO trial; phase 2) [ 20 ].…”

Generation of a Retargeted Oncolytic Herpes Virus Encoding Adenosine Deaminase for Tumor Adenosine Clearance

“…OVs offer the unique opportunity to encode a payload of interest within the infected cancer cells to further improve antitumor immunity [52,53]. Retargeted Herpesviruses allow selective infection of cancer cells trough an antibody fragment targeting a given tumor antigen (e.g., HER2, MSLN, PSMA) [36,42,[54][55][56]. To target the adenosine pathway in HER2+ tumors, here, we took advantage of the THV R-LM113 retargeted to human HER2 by a trastuzumab-derived scFv [42].…”

“…For cytotoxicity assay, Alamar Blue was used as previously reported [56]. Briefly, SKOV3 cells were seeded in 96-well plates at a density of 10,000 cells/well in the presence of 10% FBS RPMI medium.…”

Comparison of the oncolytic activity of a replication‐competent and a replication‐deficient herpes simplex virus 1

“…A non-replicative virus may offer advantages in terms of clinical safety, for example, back mutation or recombination with virulent HSV is less likely. The latest viral strains with receptor retargeting [18,19] may be particularly well suited for systemic use to find and target distant metastases. For this application, a replication-deficient virus could be used with fewer concerns.…”