Advanced, recurrent, and persistent cervical cancer management: in the era of immunotherapy

Cervical cancer constitutes a significant health burden for women worldwide despite being preventable by vaccination and screening. Advanced stages of the disease are associated with a poor prognosis, and treatment approaches have seen little change over several decades, resulting in an overall survival rate of no more than 17 months. Additionally, there are limited options for second-line treatment. The urgent need for innovative and effective therapies to improve the outlook for this group of patients, along with an enhanced understanding of the interactions between the disease and the host’s immune system, has propelled immunotherapy into a rapidly advancing field with notable achievements. Among various immunotherapeutic approaches, immune checkpoint inhibitors emerge as the most advanced treatment option. Clinical trials assessing these inhibitors as single agents or in combination with chemotherapy show promising results. As immunotherapy begins to redefine standards of care for metastatic, recurrent, or persistent cervical cancer, this review addresses recent advances and current recommendations for its management in both first and second-line treatment. The goal is to provide insights into the evolving landscape of cervical cancer treatment, specifically focusing on immunotherapeutic interventions.


Introduction
Despite being a completely preventable disease, in developing countries, cervical cancer (CC) is a major contributor to cancerrelated deaths in women.For a long time, cisplatin as monotherapy or in combination represented the standard treatment for this patient group, with an overall survival not exceeding 13 months.In recent years, the advent of targeted therapies such as immunotherapy has significantly improved the prognosis for these patients.

Immunity and cervical cancer
Human Papillomavirus (HPV) is a necessary but not sufficient etiological factor for developing cervical cancer.Infected basal epithelial cells hosting HPV express only early genes.However, HPV integration into the host genome leads to the expression of oncogenes E6 and E7 (1,2).Integration of the HPV genome is a critical step in the development of HPV-associated cancers.This integration event preferentially occurs at fragile sites within the human DNA, regions characterized by increased susceptibility to breakage and rearrangement.The subsequent expression of viral oncogenes E6 and E7 is not only essential for the initiation and progression of premalignant lesions but also actively promotes genomic instability, further contributing to cellular transformation and malignant progression (3).
HPV-infected cells can evade immunosurveillance by inhibiting acute inflammation and immunological recognition.This viral and inflammatory cancer environment has been shown to be responsible for inducing PD-L1 expression (4).There is evidence that PD-L1 expression plays a significant role in creating an "immune privileged" site for initiating and persisting HPV infection by downregulating T-cell activity and generating adaptive immune resistance (5,6).High-level PD-L1 expression is rare in healthy cervical tissue, but is increased in T cells and tumoral cells in 35 to 96% of cervical cancers (7).
Immunological escape is associated with local negative regulation as well as evasion of immune system detection, including increased regulatory T cells (Treg), loss of major histocompatibility complex (MHC) antigen presentation, chronic inflammation, and regulation of immune checkpoint molecules (8).Targeting tumor-specific antigens remains a cornerstone of cancer immunotherapy.However, the immunosuppressive tumor microenvironment presents a significant challenge, often hindering the efficacy of such targeted approaches.Therefore, therapeutic strategies aimed at reversing this immunosuppression within the tumor microenvironment are crucial for enhancing the efficacy of cancer immunotherapy.This can involve approaches such as inhibiting checkpoint molecules, depleting regulatory T cells, or promoting the activity of immunostimulatory cells and cytokines.Therapeutic interventions, such as immune checkpoint blockade targeting molecules like PD-1/PD-L1 and CTLA-4, aim to overcome this challenge; they are not specific for HPV antigens, and if successful, they can be efficient in the majority of cervical cancer cases, regardless of the associated HPV type (9).Tumor cells often exploit immune checkpoint pathways as a mechanism for immune evasion.Therapeutic interventions targeting immune checkpoints, such as PD-1/PD-L1 blockade, can restore T cell function and promote tumor cell killing.By preventing the inhibitory signals mediated by these checkpoints, T cell proliferation and cytotoxic activity against cancer cells are enhanced within the tumor microenvironment.

Immune checkpoint inhibitors
The application of immunotherapy in CC treatment is grounded in several key molecular features observed in these tumors.Elevated Tumor Mutational Burden, Microsatellite Instability, high PD-L1 expression, and elevated Tumor Inflammatory State, suggest an environment conducive to successful immunotherapy intervention.Therefore, the convergence of these molecular features in CC provides a strong rationale for employing immunotherapy as a treatment strategy (10).
Various tumors, including CC, express PD-L1, an immune checkpoint molecule mediating tumor cell escape from immune system-mediated destruction (11).PD-L1 expression by tumors enables them to evade destruction by CD8+ T cells.PD-1 is a crucial immune checkpoint molecule involved in maintaining selftolerance and modulating the immune response.During an inflammatory response to infection, PD-1 expression on activated effector T cells helps prevent autoimmunity by attenuating T cell activation.However, within the tumor microenvironment, PD-1 can contribute to immune resistance.PD-1 is expressed on various immune cells, including activated T cells and regulatory T cells (Tregs).Notably, PD-1 expression on Tregs, coupled with ligand engagement, enhances their proliferation and amplifies their immunosuppressive function.Furthermore, PD-1 expression extends beyond T lymphocytes to include B cells and other immune subsets (9).
PD-L1 and PD-L2 serve as the two ligands for PD-1.Binding of either ligand to PD-1 triggers a co-inhibitory signal within activated T cells, leading to suppression of their effector functions.In the context of cancer, PD-1 is frequently upregulated on tumor-infiltrating lymphocytes (TILs) across diverse tumor types (12).This, coupled with the common overexpression of PD-L1 on tumor cells, facilitates immune evasion by inhibiting anti-tumor T cell responses (13, 14).Further, PD-L1 expression is an independent prognostic factor for poor outcome, irrespective of established clinicopathological features, including stage, tumor size, depth of invasion, lymphovascular invasion, and lymph node involvement (15).

First-line treatment and recent advances
Advanced, persistent, or recurrent CC has a 5-year survival rate of 17%.Thus, median progression-free survival (PFS) (2 to 5 months) and overall survival (OS) (5 to 16 months) is low for individuals who can't undergo surgery or radiotherapy (16).
For many years, platinum-based chemotherapy represented the standard treatment for this patient group, with response rates of 13% and 36% for monotherapy or combination therapy, respectively (17)(18)(19).The GOG 204 study, comparing four cisplatin combinations (cisplatin/paclitaxel, cisplatin/topotecan, cisplatin/gemcitabine, and cisplatin/vinorelbine), found no difference in overall survival.While not statistically significant, a trend towards improved efficacy was observed in the cisplatin/ paclitaxel group compared to the other treatment combinations.This trend was evidenced by numerically higher response rates, as well as longer progression-free survival (PFS) and overall survival (OS) (12.9 months vs. 10 months), which have established it as the preferred regimen since 2009 (17).Subsequently, the phase III JCOG0505 non-inferiority study comparing carboplatin/paclitaxel vs. cisplatin/paclitaxel demonstrated the non-inferiority of the carboplatin/paclitaxel regimen in terms of median overall survival (17.5 months vs. 18.3 months, p=0.032), with a different toxicity profile but consolidating platinum and taxane chemotherapy as the first-line treatment choice (19).
In 2014, the first targeted therapy with a benefit in metastatic, recurrent or persistent cervical cancer was established with the GOG 240 study.Bevacizumab, a monoclonal antibody, acts as an antiangiogenic agent by neutralizing vascular endothelial growth factor (VEGF), inducing tumor vascular regression, normalizing residual vasculature, and inhibiting neovascularization and, therefore, tumor growth.The combination of bevacizumab with platinum-based chemotherapy showed a 4-month overall survival advantage compared to chemotherapy alone (17 months vs. 13 months) and a response rate of 48% vs. 36% (16).
In 2021, the KEYNOTE-826 study approved the first-line immunotherapy for palliative treatment in CC.Pembrolizumab, a monoclonal antibody, binds to the PD-1 receptor, preventing its interaction with PD-L1 and PD-L2.This interference enhances the anti-tumor immune response of T cells.This phase 3, double-blind clinical trial randomized patients with persistent, recurrent, or metastatic uterine CC to receive pembrolizumab (200 mg) or placebo every 3 weeks for up to 35 cycles plus platinum-based chemotherapy and, at the investigator's discretion, bevacizumab.In 548 patients exhibiting PD-L1 expression levels of combined positive score (CPS) ≥1%, treatment with pembrolizumab demonstrated a statistically significant improvement in both progression-free survival (PFS) and overall survival (OS) when compared to the placebo group.Specifically, the median PFS for the pembrolizumab group was 10.4 months, exceeding the 8.2 months observed in the placebo group.This difference translated to a hazard ratio (HR) of 0.62 for disease progression or death (95% confidence interval [CI], 0.50 to 0.77; p <0.001).Furthermore, the 24-month OS rate was notably higher in the pembrolizumab group, reaching 53.0% compared to 41.7% in the placebo group (HR for death, 0.64; 95% CI, 0.50 to 0.81; p <0.001).Regarding safety, the most frequently observed grade 3-5 adverse events were anemia (30.3% in the pembrolizumab group and 26.9% in the placebo group) and neutropenia (12.4% and 9.7%, respectively) (20).In 2023, the results of the study were presented, with a median followup of 39.1 months.In the PD-L1 ≥1% population, the administration of pembrolizumab demonstrated a notable improvement in median overall survival compared to the chemotherapy-placebo group.Specifically, the pembrolizumab group achieved a median overall survival of 28.6 months, whereas the control group reached 16.5 months (HR for death: 0.60; 95% CI: 0.49 to 0.74).This survival benefit was further accentuated in the subgroup analysis of patients with PD-L1 expression >10%.In this cohort, the median overall survival for the pembrolizumab arm was 29.6 months versus 17.4 months in the control arm (HR: 0.58; 95% CI: 0.44 to 0.78).Pembrolizumab also exhibited superiority in PFS compared to the control regimen.This was observed in both the PD-L1 CPS ≥1% population (HR: 0.58; p-value <0.0001) and the PD-L1 CPS ≥10% population (HR: 0.52; p-value <0.0001).Regarding adverse events, the incidence of grade 3 or higher events was 82.4% in the pembrolizumab group and 75.4% in the placebo group.

Second-line treatment options
Following initial treatment, disease progression historically presented significant challenges due to the scarcity of effective therapeutic interventions.For an extended period, a standardized second-line chemotherapy regimen remained elusive.Commonly employed chemotherapeutic agents, including taxanes, topotecan, and gemcitabine, with response rates of 13.2%, with a median PFS of 3.2 months, and a median OS of 9.3 months (22).
Until 2018, there were no promising treatments in the palliative second-line setting for patients with CC.The KEYNOTE-158 study in 2018 showed promising results with pembrolizumab.In this phase 3, double-blind study, participants were administered pembrolizumab at a dose of 200 mg every three weeks for two years, or until disease progression, unacceptable toxicity, or withdrawal by either the patient or physician.A total of 98 patients were treated, with 83.7% having PD-L1 positivity.After a median follow-up duration of 10.2 months (range: 0.6 -22.7 months), the observed objective response rate (ORR) was 12.2% (95% confidence interval [CI]: 6.5% -20.4%).This included three complete responses and nine partial responses, all occurring within the PD-L1-positive patient subgroup.Consequently, the ORR for PD-L1-positive patients was 14.6% (95% CI: 7.8% -24.2%).Notably, 14.3% (95% CI: 7.4% -24.1%) of responders within this subgroup had previously received one or more lines of chemotherapy in the recurrent or metastatic setting.Treatmentrelated adverse events were observed in 65.3% of the study population.The most frequently reported adverse events included hypothyroidism (10.2%), decreased appetite (9.2%), and fatigue (9.2%).Grade 3-4 treatment-related adverse events were documented in 12.2% of patients (23).
In 2022, another treatment showed promising results in this patient group.The EMPOWER-Cervical 1 study, a phase 3 trial, in patients who had disease progression after first-line platinum-based chemotherapy, regardless of their PD-L1 status.Cemiplimab, a monoclonal antibody, similarly to pembrolizumab, targets PD-1, preventing T-cell inactivation, and enhancing T-cell mediated immune responses against tumors.This randomized controlled trial investigated the efficacy and safety of cemiplimab versus the investigator's choice chemotherapy in women with advanced cervical cancer.A total of 608 patients were equally randomized to receive either cemiplimab (350mg every 3 weeks) or chemotherapy.The cemiplimab group demonstrated a significant improvement in median OS compared to the chemotherapy group (12.0 months vs. 8.5 months, respectively).This survival benefit was reflected in a HR for death of 0.69 (95% CI, 0.56 to 0.84; p < 0.001) favoring cemiplimab.Notably, this survival advantage remained consistent across both squamous cell carcinoma and adenocarcinoma (including adenosquamous carcinoma) histological subgroups.PFS was also significantly longer in the cemiplimab group compared to the chemotherapy group, as evidenced by a HR for disease progression or death of 0.75 (95% CI, 0.63 to 0.89; p < 0.001).The ORR was notably higher in the cemiplimab group (16.4%; 95% CI, 12.5 to 21.1) compared to the chemotherapy group (6.3%; 95% CI, 3.8 to 9.6).Interestingly, within the cemiplimab group, the response rate was 18% (95% CI, 11 to 28) for patients with PD-L1 expression ≥1% and 11% (95% CI, 4 to 25) for those with PD-L1 expression <1%.Grade ≥3 adverse events were observed in 45.0% of patients in the cemiplimab group and 53.4% of patients in the chemotherapy group.This study suggests that cemiplimab provides a significant improvement in OS and PFS compared to chemotherapy in women with advanced CC.The observed benefit was consistent across histological subgroups and PD-L1 expression levels.While adverse events were noted in both groups, the incidence of grade ≥3 events was numerically lower in the cemiplimab group (25).
Table 1 summarizes clinical trials investigating the efficacy and safety of immunotherapy for the treatment of metastatic, recurrent, or persistent cervical cancer.
Currently, there are several phase I-II clinical trials evaluating the use of immunotherapy as second-line treatment for recurrent and persistent metastatic cervical cancer, with promising outcomes expected for this patient group (Table 2).Furthermore, the related mechanisms of combined immunotherapy with other treatments such as chemotherapy or targeted therapies, as well as combinations of immunotherapies, are being assessed in different clinical studies and are anticipated to alter current treatment guidelines in the future.

Conclusions
Cervical cancer patients facing metastatic, persistent, or recurrent disease experience a dismal prognosis, with a 5-year survival rate below 20%.This underscores the critical need for novel therapeutic interventions to improve outcomes for this patient population.Recent advancements in understanding the mechanisms of immunosuppression within the tumor microenvironment have paved the way for the development of innovative immunotherapeutic strategies.These approaches aim to counteract immunosuppressive pathways and bolster effector immune cell function, leading to promising improvements in both progression-free survival (PFS) and overall survival (OS), particularly in the first-line treatment setting.

Recommendations
• The use of pembrolizumab with platinum + paclitaxel ± bevacizumab is recommended for patients with metastatic, recurrent, or persistent CC with PD-L1 CPS ≥1%, of squamous, adenocarcinoma, or adenosquamous histology, as first-line treatment.Quality of evidence (GRADE: High) Level of recommendation IA.

TABLE 1
Advanced, recurrent, and persistent cervical cancer targeted therapies.

TABLE 2
Therapies under investigation for the treatment of advanced, persistent, and recurrent cervical cancer.Programmed cell death protein 1; CTLA-4, Cytotoxic T-lymphocyte-associated protein 4; SCC, Squamous Cell Carcinoma; AC, Adenocarcinoma; ACS, Adenosquamous Carcinoma; IV, Intravenous; Q2W, Every 2 weeks; ORR, Objective Response Rate; PD-L1, Programmed Death-Ligand 1; rTKI, Receptor Tyrosine Kinase Inhibitor; PFS, Progression-Free Survival; RECIST, Response Evaluation Criteria in Solid Tumors; OS, Overall Survival; IRC, Independent Review Committee; Q6W, Every 6 weeks; TIGIT, T cell immunoreceptor with Ig and ITIM domains.persistent CC, of squamous, adenocarcinoma, or adenosquamous histology, with progression on at least one line of platinum-based chemotherapy (PD-L1 CPS ≥1%, MSI-H, dMMR, TMB-H).Quality of evidence (GRADE: Moderate) Level of recommendation IIB.• The use of tisotumab/vedontin is recommended in patients with metastatic, recurrent, or persistent CC, of squamous, adenocarcinoma, or adenosquamous histology, with progression on chemotherapy, as second-line treatment.Quality of evidence (GRADE: Moderate) Level of recommendation IIB.• The use of cemiplimab monotherapy is recommended in patients with metastatic, recurrent, or persistent CC, of squamous, adenocarcinoma, or adenosquamous histology, with progression on chemotherapy, as second-line treatment.Quality of evidence (GRADE: High) Level of recommendation IB. • The use of chemotherapy as monotherapy (paclitaxel, docetaxel, gemcitabine, topotecan, vinorelbine) may be an option in second-line treatment for patients with advanced, recurrent, or persistent CC, not eligible for immunotherapy.Quality of evidence (GRADE: Moderate) Level of recommendation IIB.