Barriers to Immunotherapy in Ovarian Cancer: Metabolic, Genomic, and Immune Perturbations in the Tumour Microenvironment

A lack of explicit early clinical signs and effective screening measures mean that ovarian cancer (OC) often presents as advanced, incurable disease. While conventional treatment combines maximal cytoreductive surgery and platinum-based chemotherapy, patients frequently develop chemoresistance and disease recurrence. The clinical application of immune checkpoint blockade (ICB) aims to restore anti-cancer T-cell function in the tumour microenvironment (TME). Disappointingly, even though tumour infiltrating lymphocytes are associated with superior survival in OC, ICB has offered limited therapeutic benefits. Herein, we discuss specific TME features that prevent ICB from reaching its full potential, focussing in particular on the challenges created by immune, genomic and metabolic alterations. We explore both recent and current therapeutic strategies aiming to overcome these hurdles, including the synergistic effect of combination treatments with immune-based strategies and review the status quo of current clinical trials aiming to maximise the success of immunotherapy in OC.

Perspectives on Hypoxia Signaling in Tumor Stroma

Hypoxia is a well-known characteristic of solid tumors that contributes to tumor progression and metastasis. Oxygen deprivation due to high demand of proliferating cancer cells and standard of care therapies induce hypoxia. Hypoxia signaling, mainly mediated by the hypoxia-inducible transcription factor (HIF) family, results in tumor cell migration, proliferation, metabolic changes, and resistance to therapy. Additionally, the hypoxic tumor microenvironment impacts multiple cellular and non-cellular compartments in the tumor stroma, including disordered tumor vasculature, homeostasis of ECM. Hypoxia also has a multifaceted and often contradictory influence on immune cell function, which contributes to an immunosuppressive environment. Here, we review the important function of HIF in tumor stromal components and summarize current clinical trials targeting hypoxia. We provide an overview of hypoxia signaling in tumor stroma that might help address some of the challenges associated with hypoxia-targeted therapies.

Perspectives in Breast and Ovarian Cancer Chemotherapy by Nanomedicine Approach: Nanoformulations in Clinical Research

BACKGROUND

Breast and ovarian carcinomas represent major health problems in women worldwide. Chemotherapy constitutes the main treatment strategy, and the use of nanocarriers, a good tool to improve it. Several nanoformulations have already been approved, and others are under clinical trials for the treatment of both types of cancers.

OBJECTIVE

This review focuses on the analysis of the nanoformulations that are under clinical research in the treatment of these neoplasms.

RESULTS

Currently, there are 6 nanoformulations in clinical trials for breast and ovarian carcinomas, most of them in phase II and phase III. In the case of breast cancer treatment, these nanomedicines contain paclitaxel; and, for ovarian cancer, nanoformulations containing paclitaxel or camptothecin analogs are being evaluated. The nanoencapsulation of these antineoplastics facilitates their administration and reduces their systemic toxicity. Nevertheless, the final approval and commercialization of nanoformulations may be limited by other aspects like lack of correlation between the efficacy results evaluated at in vitro and in vivo levels, difficulty in producing large batches of nanoformulations in a reproducible manner and high production costs compared to conventional formulations of antineoplastics. However, these challenges are not insurmountable and the number of approved nanoformulations for cancer therapy is growing.

CONCLUSION

Reviewed nanoformulations have shown, in general, excellent results, demonstrating a good safety profile, a higher maximum tolerated dose and a similar or even slightly better antitumor efficacy compared to the administration of free drugs, reinforcing the use of nano-chemotherapy in both breast and ovarian tumors.

Translational impact of nanoparticle-drug conjugate CRLX101 with or without bevacizumab in advanced ovarian cancer

PURPOSE

Increased tumor hypoxia and hence elevated hypoxia-inducible factor-1α (HIF1α) is thought to limit the efficacy of vascular endothelial growth factor (VEGF) pathway-targeting drugs by upregulating adaptive resistance genes. One strategy to counteract this is to combine antiangiogenic drugs with agents able to suppress HIF1α. One such possibility is the investigational drug CRLX101, a nanoparticle-drug conjugate (NDC) containing the payload camptothecin, a known topoisomerase-I poison.

EXPERIMENTAL DESIGN

CRLX101 was evaluated both as a monotherapy and combination with bevacizumab in a preclinical mouse model of advanced metastatic ovarian cancer. These preclinical studies contributed to the rationale for undertaking a phase II clinical study to evaluate CRLX101 monotherapy in patients with advanced platinum-resistant ovarian cancer.

RESULTS

Preclinically, CRLX101 is highly efficacious as a monotherapy when administered at maximum-tolerated doses. Furthermore, chronic low-dose CRLX101 with bevacizumab reduced bevacizumab-induced HIF1α upregulation and resulted in synergistic efficacy, with minimal toxicity in mice. In parallel, initial data reported here from an ongoing phase II clinical study of CRLX101 monotherapy shows measurable tumor reductions in 74% of patients and a 16% RECIST response rate to date.

CONCLUSIONS

Given these preclinical and initial clinical results, further clinical studies are currently evaluating CRLX101 in combination with bevacizumab in ovarian cancer and warrant the evaluation of this therapy combination in other cancer types where HIF1α is implicated in pathogenesis, as it may potentially be able to improve the efficacy of antiangiogenic drugs.