Integrating Cancer Vaccines in the Standard-of-Care of Ovarian Cancer: Translating Preclinical Models to Human

Simple Summary

The overall survival of ovarian cancer (OC) remains poor for most patients. Despite incorporation of novel therapeutic agents such as bevacizumab and PARP inhibitors to OC standard-of-care, efficacy is only observed in a subset of patients. Cancer vaccination has demonstrated effectiveness in OC patients and could be considered for potential incorporation into OC standard-of-care. This review provides an overview of the different types of cancer vaccination strategies and discusses the use of murine OC tumor models to evaluate combinatorial regimens comprising cancer vaccines and OC standard-of-care.

Abstract

As the majority of ovarian cancer (OC) patients are diagnosed with metastatic disease, less than 40% will survive past 5 years after diagnosis. OC is characterized by a succession of remissions and recurrences. The most promising time point for immunotherapeutic interventions in OC is following debulking surgery. Accumulating evidence shows that T cells are important in OC; thus, cancer vaccines capable of eliciting antitumor T cells will be effective in OC treatment. In this review, we discuss different cancer vaccines and propose strategies for their incorporation into the OC standard-of-care regimens. Using the murine ID8 ovarian tumor model, we provide evidence that a cancer vaccine can be effectively combined with OC standard-of-care to achieve greater overall efficacy. We demonstrate several important similarities between the ID8 model and OC patients, in terms of response to immunotherapies, and the ID8 model can be an important tool for evaluating combinatorial regimens and clinical trial designs in OC. Other emerging models, including patient-derived xenograft and genetically engineered mouse models, are continuing to improve and can be useful for evaluating cancer vaccination therapies in the near future. Here, we provide a comprehensive review of the completed and current clinical trials evaluating cancer vaccines in OC.

Randomized phase IIB evaluation of weekly paclitaxel versus weekly paclitaxel with oncolytic reovirus (Reolysin®) in recurrent ovarian, tubal, or peritoneal cancer: An NRG Oncology/Gynecologic Oncology Group study

OBJECTIVE

To assess whether the addition of oncolytic reovirus (Reolysin®) to weekly paclitaxel prolonged progression-free survival (PFS) in the treatment of women with recurrent or persistent ovarian, tubal or primary peritoneal cancer.

PATIENTS AND METHODS

Patients with recurrent or persistent epithelial ovarian, tubal, or peritoneal carcinoma, measurable or detectable disease, and three or fewer prior regimens were randomly assigned to paclitaxel (80mg/m² intravenously days 1, 8, and 15 every 4weeks) or the combination of paclitaxel (80mg/m² intravenously days 1, 8, and 15) plus reovirus 3×10¹⁰TCID₅₀/day intravenously on days 1-5, both every 4weeks until disease progression or toxicity. The primary end point was PFS. The study was designed with 80% power for a one-sided alternative at a 10% level of significance to detect a reduction in the hazard by 37.5%.

RESULTS

The study accrued 108 patients, 100 of whom were evaluable for toxicity. Median PFS was 4.3months for paclitaxel and 4.4months for paclitaxel plus reovirus (hazard ratio, 1.11; 90% two-sided CI, 0.78 to 1.59; one-sided P=0.687). The proportion responding (overall response rate) to paclitaxel was 20% among 45 patients with measurable disease receiving paclitaxel alone, and 17.4% among the 46 patients treated with the combination. The asymptotic relative probability of responding was 0.87 (90% CI, 0.42 to 1.79). Severe adverse events were more common in the combination regimen than in paclitaxel arm for severe neutropenia (grade≥4, 12% versus 0%), and severe respiratory adverse events (grade≥3, 25% versus 2%). No deaths were considered treatment related.

CONCLUSION

The addition of reovirus to weekly paclitaxel in the treatment of women with recurrent or persistent ovarian, tubal or peritoneal cancer did not sufficiently reduce the hazard of progression or death to warrant further investigation.

The use of immunohistochemistry to determine oncolytic reovirus distribution and replication in-human tumors

An oncolytic virus is considered a targeted cancer therapy due to its ability to specifically target, replicate in and lyse cancer cells while leaving normal cells unharmed. Over the last few years several tumor selective oncolytic viruses have been developed. These include certain DNA viruses such as adenovirus that have been genetically manipulated to target specific cancer cells by exerting restrictions on the virus at the level of cell entry, viral gene transcription and viral protein translation. There are a variety of RNA viruses being studied as possible cancer therapies including reovirus. Reovirus is intrinsically oncolytic without the need for any genetic manipulation. The inherent oncolytic properties of this virus are derived from the fact that it specifically targets cells with an activated Ras pathway found in many cancer cells. REOLYSIN® is a proprietary formulation of human reovirus type 3 Dearing developed by Oncolytics Biotech Inc. and is the only therapeutic reovirus in clinical development. This review provides an overview of the development of REOLYSIN as a potential cancer therapeutic and the growing role of in situ based molecular pathology methods in providing clinical proof of concept and in guiding clinical development.