Attacking Postoperative Metastases using Perioperative Oncolytic Viruses and Viral Vaccines

The use of oncolytic virotherapy in the neoadjuvant setting

Surgical removal of tumors remains a front-line therapy for many types of cancer. However, this treatment often fails to eradicate disease due to either recurrence of the original tumor or development of distant micrometastases. To address these challenges, patients are often given non-curative treatments presurgery with the intent of improving surgical outcomes. These treatments, collectively known as neoadjuvant therapies, have traditionally focused on the presurgical use of chemotherapeutics. Recently, however, a variety of immunotherapies have also been identified as potentially effective in the neoadjuvant setting. One of these immunotherapies is oncolytic virotherapy, whose clinical use has exploded with the Food and Drug Administration approval of Talimogene Laherparepvec. This review summarizes both the preclinical and clinical literature examining the use of oncolytic virotherapy in the neoadjuvant setting for different types of cancers and discusses some of the major questions that still need to be addressed in order for this unique use of immunotherapy to become clinically viable.

Effects of recombinant human adenovirus type 5 combined with transarterial chemoembolization on postoperative metastasis and recurrence of hepatocellular carcinoma patients

BACKGROUND

Postoperative recurrence is currently the main factor affecting the long-term survival of hepatocellular carcinoma (HCC) patients. The folinic acid, fluorouracil, and oxaliplatin (FOLFOX) regimen with transarterial chemoembolization (TACE) is a commonly used postoperative chemotherapy strategy, but its effect is still limited. The aim of this study was to analyze the effects of recombinant human adenovirus type 5 (rhAd5) combined with TACE on postoperative metastasis and recurrence of HCC.

METHODS

Patients with HCC undergoing surgical treatment were collected and divided into the rhAd5 group and control group according to whether rhAd5 was performed. The rhAd5 group was combined with rhAd5 treatment based on TACE. The recurrence and metastasis rates of the two participant groups were compared. The changes of liver function, kidney function, blood routine, and adverse reactions during treatment were analyzed.

RESULTS

The basic data of the two groups were not significantly different (P>0.05). The recurrence and metastasis rates of rhAd5 group participants were significantly lower than those of the control group (P<0.05). There was no significant difference in the incidence of adverse reactions between the rhAd5 group and control group (P>0.05). There were no significant differences in the incidences of adverse reactions between the rhAd5 group and control group (P>0.05).

CONCLUSIONS

The combination of FOLFOX and rhAd5 after surgery can significantly inhibit the occurrence of metastasis and recurrence of HCC patients, improve progression free survival, and has certain safety.

The two-faces of NK cells in oncolytic virotherapy

Oncolytic viruses (OVs) are immunotherapeutics capable of directly killing cancer cells and with potent immunostimulatory properties. OVs exert their antitumor effect, at least partially, by activating the antitumor immune response, of which NK cells are an important component. However, if on the one hand increasing evidence revealed that NK cells are important mediators of oncolytic virotherapy, on the other hand, NK cells have evolved to fight viral infections, and therefore they can have a detrimental effect for the efficacy of OVs. In this review, we will discuss the dichotomy between the antitumor and antiviral functions of NK cells related to oncolytic virotherapy. We will also review NK cell-based and OV-based therapies, engineered OVs aimed at enhancing immune stimulation, and combination therapies involving OVs and NK cells currently used in cancer immunotherapy.

Preoperative stimulation of resolution and inflammation blockade eradicates micrometastases

Cancer therapy is a double-edged sword, as surgery and chemotherapy can induce an inflammatory/immunosuppressive injury response that promotes dormancy escape and tumor recurrence. We hypothesized that these events could be altered by early blockade of the inflammatory cascade and/or by accelerating the resolution of inflammation. Preoperative, but not postoperative, administration of the nonsteroidal antiinflammatory drug ketorolac and/or resolvins, a family of specialized proresolving autacoid mediators, eliminated micrometastases in multiple tumor-resection models, resulting in long-term survival. Ketorolac unleashed anticancer T cell immunity that was augmented by immune checkpoint blockade, negated by adjuvant chemotherapy, and dependent on inhibition of the COX-1/thromboxane A2 (TXA2) pathway. Preoperative stimulation of inflammation resolution via resolvins (RvD2, RvD3, and RvD4) inhibited metastases and induced T cell responses. Ketorolac and resolvins exhibited synergistic antitumor activity and prevented surgery- or chemotherapy-induced dormancy escape. Thus, simultaneously blocking the ensuing proinflammatory response and activating endogenous resolution programs before surgery may eliminate micrometastases and reduce tumor recurrence.

Potentiating Oncolytic Virus-Induced Immune-Mediated Tumor Cell Killing Using Histone Deacetylase Inhibition

A clinical oncolytic herpes simplex virus (HSV) encoding granulocyte-macrophage colony-stimulating factor (GM-CSF), talimogene laherparepvec, causes regression of injected and non-injected melanoma lesions in patients and is now licensed for clinical use in advanced melanoma. To date, limited data are available regarding the mechanisms of human anti-tumor immune priming, an improved understanding of which could inform the development of future combination strategies with improved efficacy. This study addressed direct oncolysis and innate and adaptive human immune-mediated effects of a closely related HSV encoding GM-CSF (HSVGM-CSF) alone and in combination with histone deacetylase inhibition. We found that HSVGM-CSF supported activation of anti-melanoma immunity via monocyte-mediated type I interferon production, which activates NK cells, and viral maturation of immature dendritic cells (iDCs) into potent antigen-presenting cells for cytotoxic T lymphocyte (CTL) priming. Addition of the histone deacetylase inhibitor valproic acid (VPA) to HSVGM-CSF treatment of tumor cells increased viral replication, viral GM-CSF production, and oncolysis and augmented the development of anti-tumor immunity. Mechanistically, VPA increased expression of activating ligands for NK cell recognition and induced expression of tumor-associated antigens, supporting innate NK cell killing and CTL priming. These data support the clinical combination of talimogene laherparepvec with histone deacetylase inhibition to enhance oncolysis and anti-tumor immunity.

Combining surgery and immunotherapy: turning an immunosuppressive effect into a therapeutic opportunity

Background

Cancer surgery is necessary and life-saving. However, the majority of patients develop postoperative recurrence and metastasis, which are the main causes of cancer-related deaths. The postoperative stress response encompasses a broad set of physiological changes that have evolved to safeguard the host following major tissue trauma. These stress responses, however, intersect with cellular mediators and signaling pathways that contribute to cancer proliferation.

Main

Previous descriptive and emerging mechanistic studies suggest that the surgery-induced prometastatic effect is linked to impairment of both innate and adaptive immunity. Existing studies that combine surgery and immunotherapies have revealed that this combination strategy is not straightforward and patients have experienced both therapeutic benefit and drawbacks. This review will specifically assess the immunological pathways that are disrupted by oncologic surgical stress and provide suggestions for rationally combining cancer surgery with immunotherapies to improve immune and treatment outcomes.

Short conclusion

Given the prevalence of surgery as frontline therapy for solid cancers, the emerging data on postoperative immunosuppression and the rapid development of immunotherapy for oncologic treatment, we believe that future targeted studies of perioperative immunotherapy are warranted.

The hemagglutinin-neuramidinase protein of Newcastle disease virus upregulates expression of the TRAIL gene in murine natural killer cells through the activation of Syk and NF-κB

Newcastle disease virus (NDV) is responsible for tumoricidal activity in vitro and in vivo. However, the mechanisms that lead to this activity are unclear. Natural killer cells are able to induce apoptosis of tumor cells through multiple pathways, including the tumor necrosis factor-related apoptosis-inducing ligand-death receptor pathway. We previously showed that exposure of NK and T cells to NDV resulted in enhanced tumoricidal activity that was mediated by upregulated expression of the TRAIL gene, via an interferon gamma -dependent pathway. Other pathways involved in the upregulated expression of TRAIL are yet to be identified. In the current study, we used mice in which the IFN-γ receptor one gene was inactivated functionally. We identified an IFN-γ-independent TRAIL pathway in the NDV-stimulated NK cells. Hemagglutinin-neuramidinase induced expression of the TRAIL gene in IFN-R1-/- NK cells by binding to the NKp46 receptor. This upregulation was inhibited by pretreatment of NDV with a neutralizing monoclonal antibody against HN, or desialylation of NK cells. Phosphorylation of spleen tryosine kinases and IκBα was increased in HN-induced IFN-R1-/- NK cells. Treatment with the HN neutralizing monoclonal antibody, pharmacological disialylation, or a Syk inhibitor decreased Syk and IκBα phosphorylation levels. We concluded that killer activation receptors pathway is involved in the IFN-γ-independent TRAIL expression of NDV-stimulated NK cells, and these are activated by Syk and NF-κB.

Post-Operative Infection Is an Independent Risk Factor for Worse Long-Term Survival after Colorectal Cancer Surgery

BACKGROUND

Colorectal cancer surgery is associated with a high incidence of post-operative infections, the outcome of which may be improved if diagnosed and treated early enough. We compared white blood cell (WBC) count, C-reactive protein (CRP), and procalcitonin (PCT) as predictors of post-operative infections and analyzed their impact on long-term survival.

METHODS

This retrospective study included 186 patients undergoing colorectal surgery. Post-operative values of WBC, CRP, and PCT were analyzed by the receiver operating characteristic (ROC) analysis. We followed infections 30 d after the surgery. A five-year survival was analyzed by Kaplan-Meier method and prognostic factors by Cox regression model.

RESULTS

Fifty-five patients (29.5%) developed post-operative infection, the most frequent of which was surgical site infection (SSI). C-reactive protein on post-operative day three and PCT on post-operative day two demonstrated the highest diagnostic accuracy for infection (area under the curve [AUC] 0.739 and 0.735). C-reactive protein on post-operative day three was an independent predictor of infection. Five-year survival was higher in the non-infected group (70.8%), compared with the infected group (52.1%). The worst survival (40.9%) was identified in patients with organ/space SSI. Post-operative infection and tumor stage III-IV were independent predictors of a worse five-year survival.

CONCLUSIONS

C-reactive protein on post-operative day three and PCT on post-operative day two may be early predictors of infection after colorectal cancer surgery. Post-operative infections in particular organ/space SSI have a negative impact on long-term survival.

Emerging role of Natural killer cells in oncolytic virotherapy

Natural killer (NK) cells constitute a subtype of lymphocytes that initiate innate immune responses against tumors and virus-infected cells. The ability of NK cells to kill target cells or to produce cytokines depends on the balance between signals from activating and inhibitory cell-surface receptors. Therapies with NK cells involve activation of endogenous NK cells and/or exogenous transfer by hematopoietic stem cell transplantation/adoptive cell therapy. To exploit the diverse functional abilities of NK cells for cancer immunotherapy, it is important to understand NK cell biology and the underlying regulatory mechanisms. The state of immune suppression prevalent in malignancies creates the need for innovative therapies. Oncolytic viruses are novel anticancer agents showing selective tropism for tumor cells and lacking pathogenicity in humans, but the use of oncolytic virotherapy (OVT) presents multiple challenges. An increasing body of evidence suggests that the host immune response may critically influence the outcome of OVT. Classically, the immune system is thought to limit the efficacy of therapy through virus clearance mediated by innate immune effectors or through adaptive antiviral immune responses eliminating infected cells. Effective strategies do need to be designed in OVT to circumvent the early antiviral activity of NK cells and to augment late NK-cell-mediated antitumor responses. The intrinsic immunostimulating capacity of oncolytic viruses and the possibility of engineering them to express heterologous immunostimulatory molecules (eg, cytokines) support the use of these agents to enhance antitumor immune responses besides inducing direct oncolytic effects. OVT has indeed shown promising therapeutic outcomes in various clinical trials. Here, we review the biology of NK cells, strategies involving NK cells for achieving cancer therapy, and, more particularly, the emerging role of NK cells in OVT.