Vaccinia virus oncolysates in the treatment of malignant melanoma

Whole tumor antigen vaccines

Although cancer vaccines with defined antigens are commonly used, the use of whole tumor cell preparations in tumor immunotherapy is a very promising approach and can obviate some important limitations in vaccine development. Whole tumor cells are a good source of TAAs and can induce simultaneous CTLs and CD4(+) T helper cell activation. We review current approaches to prepare whole tumor cell vaccines, including traditional methods of freeze-thaw lysates, tumor cells treated with ultraviolet irradiation, and RNA electroporation, along with more recent methods to increase tumor cell immunogenicity with HOCl oxidation or infection with replication-incompetent herpes simplex virus.

Immunotherapy opportunities in ovarian cancer

Ovarian cancer is responsible for the majority of gynecologic cancer deaths and despite the highest standard of multimodality therapy with surgery and cytotoxic chemotherapy, long-term survival remains low. With compelling evidence that epithelial ovarian cancer is an immunogenic tumor capable of stimulating an antitumor immune response, renewed efforts to develop immune therapies to augment the efficacy of traditional therapies are underway. Current immunotherapies focus on varied modes of antitumor vaccine development, particularly with the use of dendritic cell vaccines, effective methods for adoptive T-cell transfer and combinatorial approaches with immune modulatory therapy subverting natural tolerance mechanisms or boosting effector mechanisms. Additional combinatorial approaches include the use of cytokines and/or chemotherapy with immune therapy.

Immunotherapy for gynaecological malignancies

Gynaecological malignancies, excluding breast cancer, cause approximately 25,000 deaths yearly among women in the US. Therefore, novel approaches for the prevention or treatment of these diseases are urgently required. In the case of cervical cancer, human papillomavirus (HPV) xenoantigens are readily recognised by the immune system, and their targeting has shown great promise in preclinical models of therapeutic vaccination and in clinical studies of preventative vaccination. A growing body of evidence indicates that ovarian cancer is also immunogenic and can thus be targeted through immunotherapy. This review outlines the principles and problems of immunotherapy for cervical and ovarian cancer, including the authors' personal assessment.

Viral oncolysates as human tumor vaccines

Postoncolytic immunity entails immune reactions acquired through an oncolytic virus infection or through repeated immunizations with viral oncolysates (or virally modified tumor cell membranes) that are valid and operational also against virally not modified tumor cells of the same type. NK cells react to budding virions, induce target cell lysis primarily but not exclusively by the production of granzymes and pore-forming proteins and operate without direction from memory cells. In contrast, immune T cells (including some TIL) are MHC-restricted, act under the direction of memory cells and lyse target cells primarily but not exclusively by the release of lymphotoxin (TNF beta) causing programmed cell death (apoptosis) through endonuclease activation and target cell DNA fragmentation. This author proposes that it is not NK, but the immune T cells that mediate postoncolytic immunity. Oncogene amplification may protect immortalized tumor cells even when expressing peptide antigens through MHC molecules against lymphotoxin-mediated apoptosis; but virally-infected tumor cells releasing budding virions remain susceptible to NK cells. Highly immunogenic viral oncolysates should present both budding virions for NK cells and processed viral and tumoral peptide antigens co-jointly for immune T cells.