Oncolytic herpes simplex viruses (oHSVs) showed efficacy in clinical trials and practice. Most of them gain cancer-specificity from deletions/mutations in genes that counteract the host response, and grow selectively in cancer cells defective in anti-viral response. Because of the deletions/mutations, they are frequently attenuated or over-attenuated. We developed next-generation oHSVs, which carry no deletion/mutation, gain cancer-specificity from specific retargeting to tumor cell receptors—e.g. HER2 (human epidermal growth factor receptor 2)—hence are fully-virulent in the targeted cancer cells. The type of immunotherapy they elicit was not predictable, since non-attenuated HSVs induce and then dampen the innate response, whereas deleted/attenuated viruses fail to contrast it, and since the retargeted oHSVs replicate efficiently in tumor cells, but spare other cells in the tumor. We report on the first efficacy study of HER2-retargeted, fully-virulent oHSVs in immunocompetent mice. Their safety profile was very high. Both the unarmed R-LM113 and the IL-12-armed R-115 inhibited the growth of the primary HER2-Lewis lung carcinoma-1 (HER2-LLC1) tumor, R-115 being constantly more efficacious. All the mice that did not die because of the primary treated tumors, were protected from the growth of contralateral untreated tumors. The long-term survivors were protected from a second contralateral tumor, providing additional evidence for an abscopal immunotherapeutic effect. Analysis of the local response highlighted that particularly R-115 unleashed the immunosuppressive tumor microenvironment, i.e. induced immunomodulatory cytokines, including IFNγ, T-bet which promoted Th1 polarization. Some of the tumor infiltrating cells, e.g. CD4+, CD335+ cells were increased in the tumors of all responders mice, irrespective of which virus was employed, whereas CD8+, Foxp3+, CD141+ were increased and CD11b+ cells were decreased preferentially in R-115-treated mice. The durable response included a breakage of tolerance towards both HER2 and the wt tumor cells, and underscored a systemic immunotherapeutic vaccine response.

Tumors utilize a number of effective strategies, including the programmed death 1/PD ligand 1 (PD-1/PD-L1) axis, to evade immune-mediated control of their growth. PD-L1 expression is mainly induced by IFN receptor signaling or constitutively induced. Integrins are an abundantly expressed class of proteins which play multiple deleterious roles in cancer and exert proangiogenic and prosurvival activities. We asked whether αvβ3-integrin positively regulates PD-L1 expression and the anticancer immune response. We report that αvβ3-integrin regulated constitutive and IFN-induced PD-L1 expression in human and murine cancerous and noncancerous cells. αvβ3-integrin targeted STAT1 through its signaling C tail. The implantation of β3-integrin–depleted tumor cells led to a dramatic decrease in the growth of primary tumors, which exhibited reduced PD-L1 expression and became immunologically hot, with increased IFNγ content and CD8+ cell infiltration. In addition, the implantation of β3-integrin–depleted tumors elicited an abscopal immunotherapeutic effect measured as protection from the challenge tumor and durable splenocyte and serum reactivity to B16 cell antigens. These modifications to the immunosuppressive microenvironment primed cells for checkpoint (CP) blockade. When combined with anti–PD-1, β3-integrin depletion led to durable therapy and elicited an abscopal immunotherapeutic effect. We conclude that in addition to its previously known roles, αvβ3-integrin serves as a critical component of the cancer immune evasion strategy and can be an effective immunotherapy target.

Our laboratory has pursued the generation of cancer-specific oncolytic herpes simplex viruses (oHSVs) which ensure high efficacy while maintaining a high safety profile. Their blueprint included retargeting to a Tumor-Associated Antigen, e.g., HER2, coupled to detargeting from natural receptors to avoid off-target and off-tumor infections and preservation of the full complement of unmodified viral genes. These oHSVs are “fully virulent in their target cancer cells”. The 3rd generation retargeted oHSVs carry two distinct retargeting moieties, which enable infection of a producer cell line and of the target cancer cells, respectively. They can be propagated in an ad hoc Vero cell derivative at about tenfold higher yields than 1st generation recombinants, and more effectively replicate in human cancer cell lines. The R-335 and R-337 prototypes were armed with murine IL-12. Intratumorally-administered R-337 conferred almost complete protection from LLC-1-HER2 primary tumors, unleashed the tumor microenvironment immunosuppression, synergized with the checkpoint blockade and conferred long-term vaccination against distant challenge tumors. In summary, the problem intrinsic to the propagation of retargeted oHSVs—which strictly require cells positive for targeted receptors—was solved in 3rd generation viruses. They are effective as immunotherapeutic agents against primary tumors and as antigen-agnostic vaccines.

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Hutchinson–Gilford progeria syndrome (HGPS) causes premature aging in children, with adipose tissue, skin and bone deterioration, and cardiovascular impairment. In HGPS cells and mouse models, high levels of interleukin‐6, an inflammatory cytokine linked to aging processes, have been detected. Here, we show that inhibition of interleukin‐6 activity by tocilizumab, a neutralizing antibody raised against interleukin‐6 receptors, counteracts progeroid features in both HGPS fibroblasts and LmnaG609G/G609G progeroid mice. Tocilizumab treatment limits the accumulation of progerin, the toxic protein produced in HGPS cells, rescues nuclear envelope and chromatin abnormalities, and attenuates the hyperactivated DNA damage response. In vivo administration of tocilizumab reduces aortic lesions and adipose tissue dystrophy, delays the onset of lipodystrophy and kyphosis, avoids motor impairment, and preserves a good quality of life in progeroid mice. This work identifies tocilizumab as a valuable tool in HGPS therapy and, speculatively, in the treatment of a variety of aging‐related disorders.