Advances and prospects in adoptive cell transfer therapy for ovarian cancer

Cell therapies in ovarian cancer

Epithelial ovarian cancer (EOC) is the most important cause of gynecological cancer-related mortality. Despite improvements in medical therapies, particularly with the incorporation of drugs targeting homologous recombination deficiency, EOC survival rates remain low. Adoptive cell therapy (ACT) is a personalized form of immunotherapy in which autologous lymphocytes are expanded, manipulated ex vivo, and re-infused into patients to mediate cancer rejection. This highly promising novel approach with curative potential encompasses multiple strategies, including the adoptive transfer of tumor-infiltrating lymphocytes, natural killer cells, or engineered immune components such as chimeric antigen receptor (CAR) constructs and engineered T-cell receptors. Technical advances in genomics and immuno-engineering have made possible neoantigen-based ACT strategies, as well as CAR-T cells with increased cell persistence and intratumoral trafficking, which have the potential to broaden the opportunity for patients with EOC. Furthermore, dendritic cell-based immunotherapies have been tested in patients with EOC with modest but encouraging results, while the combination of DC-based vaccination as a priming modality for other cancer therapies has shown encouraging results. In this manuscript, we provide a clinically oriented historical overview of various forms of cell therapies for the treatment of EOC, with an emphasis on T-cell therapy.

Immunotherapy Advances for Epithelial Ovarian Cancer

Simple Summary

The overall five-year survival rate in epithelial ovarian cancer is 44% and has only marginally improved in the past two decades. Despite an initial response to standard treatment consisting of chemotherapy and surgical removal of tumor, the lesions invariably recur, and patients ultimately die of chemotherapy resistant disease. New treatment modalities are needed in order to improve the prognosis of women diagnosed with ovarian cancer. One such modality is immunotherapy, which aims to boost the capacity of the patient’s immune system to recognize and attack the tumor cells. We performed a retrospective study to identify some of the most promising immune therapies for epithelial ovarian cancer. Special emphasis was given to immuno-oncology clinical trials.

Abstract

New treatment modalities are needed in order to improve the prognosis of women diagnosed with epithelial ovarian cancer (EOC), the most aggressive gynecologic cancer type. Most ovarian tumors are infiltrated by immune effector cells, providing the rationale for targeted approaches that boost the existing or trigger new anti-tumor immune mechanisms. The field of immuno-oncology has experienced remarkable progress in recent years, although the results seen with single agent immunotherapies in several categories of solid tumors have yet to extend to ovarian cancer. The challenge remains to determine what treatment combinations are most suitable for this disease and which patients are likely to benefit and to identify how immunotherapy should be incorporated into EOC standard of care. We review here some of the most promising immune therapies for EOC and focus on those currently tested in clinical trials.

Preclinical and Clinical Immunotherapeutic Strategies in Epithelial Ovarian Cancer

In the past 20 years, the immune system has increasingly been recognized as a major player in tumor cell control, leading to considerable advances in cancer treatment. While promising with regards to melanoma, renal cancer and non-small cell lung cancer, immunotherapy provides, for the time being, limited success in other cancers, including ovarian cancer, potentially due to insufficient immunogenicity or to a particularly immunosuppressive microenvironment. In this review, we provide a global description of the immune context of ovarian cancer, in particular epithelial ovarian cancer (EOC). We describe the adaptive and innate components involved in the EOC immune response, including infiltrating tumor-specific T lymphocytes, B lymphocytes, and natural killer and myeloid cells. In addition, we highlight the rationale behind the use of EOC preclinical mouse models to assess resistance to immunotherapy, and we summarize the main preclinical studies that yielded anti-EOC immunotherapeutic strategies. Finally, we focus on major published or ongoing immunotherapy clinical trials concerning EOC.

Randomized Phase II Trial of Nivolumab Versus Nivolumab and Ipilimumab for Recurrent or Persistent Ovarian Cancer: An NRG Oncology Study

PURPOSE

Single-agent PD-1 blockade exhibits limited efficacy in epithelial ovarian cancer (EOC). We evaluated ipilimumab plus nivolumab compared with nivolumab alone in women with persistent or recurrent EOC.

METHODS

Eligibility criteria included measurable disease, 1-3 prior regimens, and platinum-free interval (PFI) < 12 months. Participants were randomly allocated to intravenous nivolumab (every 2 weeks) or induction with nivolumab plus ipilimumab for 4 doses (every 3 weeks), followed by every-2-week maintenance nivolumab for a maximum of 42 doses. The primary null hypothesis was equal probability of objective response within 6 months of random allocation in each arm.

RESULTS

One hundred patients were allocated to receive either nivolumab (n = 49), or nivolumab plus ipilimumab (n = 51), with PFI of < 6 months in 62%. Six (12.2%) responses occurred within 6 months in the nivolumab group and 16 (31.4%) in the nivolumab plus ipilimumab group (odds ratio, 3.28; 85% CI, 1.54 to infinity; P = .034). The median progression-free survival (PFS) was 2 and 3.9 months in the nivolumab and nivolumab plus ipilimumab groups, respectively, with a PFI-stratified hazard ratio of 0.53 (95% CI, 0.34 to 0.82); the respective hazard ratio for death was 0.79 (95% CI, 0.44 to 1.42). Grade ≥ 3 related adverse events occurred in 33% of patients in the nivolumab group and 49% in the combination group, with no treatment-related deaths. PD-L1 expression was not significantly associated with response in either treatment group.

CONCLUSION

Compared with nivolumab alone, the combination of nivolumab and ipilimumab in EOC resulted in superior response rate and longer, albeit limited, PFS, with toxicity of the combination regimen comparable to prior reports. Additional combination studies to enhance durability of the dual regimen are warranted.

Nature of tumour rejection antigens in ovarian cancer

Major progress in the analysis of human immune responses to cancer has been made through the molecular characterization of human tumour antigens. The development of therapeutic strategies for eliciting immune-mediated rejection of tumours has accelerated due to the elucidation of the molecular basis for tumour cell recognition and destruction by immune cells. Of the various human tumour antigens defined to date in ovarian cancer, the cancer-testis (CT) family of antigens have been studied extensively preclinically and clinically because of their testis-restricted expression in normal tissues and ability to elicit robust immune responses. Recent developments in cancer sequencing technologies offer a unique opportunity to identify tumour mutations with the highest likelihood of being expressed and recognized by the immune system. Such mutations, or neoantigens, could potentially serve as specific immune targets for T-cell-mediated destruction of cancer cells. This review will highlight current work in selecting tumour rejection antigens in ovarian cancer for improving the efficacy of immunotherapy.