The anti-PD-1 era of cervical cancer: achievement, opportunity, and challenge

Cervical cancer is one of the three major female gynecological malignancies, becoming a major global health challenge. Although about 90% of early-stage patients can be cured by surgery, advanced-stage patients still need new treatment methods to improve their efficacy, especially for those with recurrence and metastasis tumors. Anti-PD-1 is currently the most widely used immune checkpoint inhibitor, which has revolutionized cancer therapy for different types of cancer. Pembrolizumab has been approved for second-line treatment of R/M CC but has a modest overall response rate of about 15%. Therefore, multiple types of anti-PD-1 have entered clinical trials successively and evaluated the efficacy in combination with chemotherapy, targeted therapy, and immunotherapy. At the same time, the dual specific antibody of PD-1/CTLA-4 was also used in clinical trials of cervical cancer, and the results showed better than anti-PD-1 monotherapy. In addition, anti-PD-1 has also been shown to sensitize radiotherapy. Therefore, understanding the current research progress of anti-PD-1 will better guide clinical application. This review summarizes ongoing clinical trials and published studies of anti-PD-1 monotherapy and combination therapy in the treatment of cervical cancer, as well as discusses the potential molecular biological mechanisms of combination, aiming to provide the basic evidence for support anti-PD-1 in the treatment of cervical cancer and new insights in combination immunotherapy.

Balstilimab and other immunotherapy for recurrent and metastatic cervical cancer

Recurrent and metastatic cervical cancer is generally treated by cisplatin, paclitaxel, and bevacizumab with limited benefit this constituting an unmet need. Immune checkpoint inhibitors, namely the inhibitors of programmed death 1 and programmed death ligand 1 have been proved to be efficacious in the treatment of patients with advanced cervical cancer. Recently, a PD-1 inhibitor, pembrolizumab was approved for such cancer. However, there is much scope of improvement of current outcome. Dual blockade of cytotoxic T lymphocyte-associated protein 4 and PD-1 is an attractive therapeutic approach. It is used in other cancers and is currently proposed for cancer cervix also. Search is on for single or combined regimen showing efficacy in multiple pathological conditions of cancer cervix irrespective presence of PD-L1 in malignant tissue. An effort to meet such unmet need has culminated in inventing new immune checkpoint inhibitors namely PD-1 inhibitor, AGEN2034 (Balstilimab) and CTLA-4 inhibitor, AGEN1884 (Zalifrelimab).They have shown meaningful and durable activity as single-agent therapy in previously treated patients with persistent R/M CC in a large phase II trial (NCT03104699) in PD-L1 + and PD-L1- tumour. Responses were found both in squamous cell carcinoma & adenocarcinoma cell types. Balstilimab plus zalifrelimab combination (NCT03495882) produced improved clinical benefit over monotherapy as evidenced by higher relative response rates and longer response duration, as well as a manageable safety profile. Interesting development of this combination and other immunotherapies in R/M CC are discussed in this ensuing review.