Actualités autour des inhibiteurs de checkpoints immunitaires : enseignements issus du congrès ASCO 2017 et perspectives

Do proton pump inhibitors alter the response to immune checkpoint inhibitors in cancer patients? A meta-analysis

Introduction

Gut microbiota can significantly affect the effectiveness of immune checkpoint inhibitors (ICIs) in cancer patients. Recently, antibiotics were shown to decrease survival rate of patients treated by ICIs. Proton pump inhibitors (PPIs) can indeed modulate microbiota's diversity, therefore altering ICIs response. A meta-analysis was performed based on published data to verify this hypothesis.

Methods

In this study, over 41 publications, exploring the impact of concomitant PPI treatment on outcomes of ICI-treated patients, were analyzed. Evaluated endpoints were overall survival (OS) and progression-free survival (PFS). Pooled hazard ratios (HRs) with a 95% confidence interval (CI) were reported in ICIs in PPI users versus non-PPI users. Subgroup analyses were performed to minimize the impact of study heterogeneity and to investigate the influence of PPI on the different groups of interest. There was no evidence of publication bias for OS and PFS analysis in subgroup analysis.

Results

Forty-one studies were included in the meta-analysis, including a total of 20,042 patients. OS of patients receiving ICIs was negatively correlated in patients concomitantly treated with PPI (HR=1.37; 95%CI, 1.23-1.52). PFS of cancer patients receiving ICIs was also negatively correlated with PPI treatment (HR=1.28; 95%CI, 1.15-1.42). PPI and ICI use was associated with worst OS and PFS not only for non-small-cell lung cancer (NSCLC) or urothelial cancer patients but also for patients treated with anti PD-1 (OS) and anti PD-L1 (OS and PFS) immunotherapies when administered in non-first line and when PPI was received as baseline treatment or in 60 days before ICI initiation. PPI and ICI use also showed the worst OS and PFS for patients from Europe and Asia.

Conclusion

This meta-analysis suggests that PPI treatment leads to significantly worse outcomes in advanced cancer patients treated by ICIs in terms of PFS and OS.

Mechanisms and therapeutic potentials of cancer immunotherapy in combination with radiotherapy and/or chemotherapy

Immunotherapies based on T cells have gained significant success in the treatment of diverse cancers, however, several limitations also exist, including low response, acquired resistance and severe side effects, which lead to unfavorable outcomes. Recent studies found that traditional therapies, radiotherapy and/or chemotherapy may affect the immune condition in situ and cause abscopal effect, which may improve the response of immunotherapies, enhance the efficiency, and reduce the untoward effect. Here, we review the mechanisms uncovering the cancer immunotherapy and immunogenic effects of radiotherapy and chemotherapy, aiming to highlight the principles underlying the therapeutic potentials of cancer immunotherapy in combination with radiotherapy and/or chemotherapy and ultimately guide better designs for future synergistic cancer therapies.

Therapeutic efficacy of intra-tumor AvidinOX and low systemic dose biotinylated cetuximab, with and without cisplatin, in an orthotopic model of head and neck cancer

In a previous study, the efficacy of low intraperitoneal doses of biotinylated cetuximab (bCet) in mice with subcutaneous tumor xenografts of human head and neck cancer (HNC) treated intra-tumors with AvidinOX was reported. Taking into account that the current standard treatment for HNC is the combination of cetuximab and cisplatin, the present study investigated the activity of AvidinOX-targeted bCet with and without cisplatin in an orthotopic model. The results confirmed that administration of intra-tumor AvidinOX makes an otherwise inactive dose of bCet effective in reducing tumor growth, and the addition of a low dose of cisplatin further improved tumor growth inhibition. Supporting the in vivo data, immunohistochemical staining of tumor masses from mice treated with AvidinOX, bCet and cisplatin exhibited the highest tumor cell damage and the lowest angiogenic activity among all treatment groups, measured as the number of γ-H2A.X and cleaved caspase-3-positive cells, and vascular endothelial growth factor-C and platelet and endothelial cell adhesion molecule 1-positive cells, respectively. AvidinOX is currently under clinical investigation to assess its use in delivering radioactive biotin to inoperable tumor lesions (ClinicalTrials.gov: NCT02053324 and NCT03188328). The present study further supported the potential clinical use of AvidinOX to target low bCet doses to inoperable tumor lesions, with or without an additional low dose of cisplatin. Since low doses of highly expensive monoclonal antibodies become effective with AvidinOX and low dose cisplatin, such therapies promise to be cheaper and less toxic than current treatments.

Time for radioimmunotherapy: an overview to bring improvements in clinical practice

Harnessing the patient's own immune system against an established cancer has proven to be a successful strategy. Within the last years, several antibodies blocking critical "checkpoints" that control the activation of T cells, the immune cells able to kill cancer cells, have been approved for the use in patients with different tumours. Unfortunately, these cases remain a minority. Over the last years, radiotherapy has been reported as a means to turn a patient's own tumour into an in situ vaccine and generate anti-tumour T cells in patients who lack sufficient anti-tumour immunity. Indeed, review data show that the strategy of blocking multiple selected immune inhibitory targets in combination with radiotherapy has the potential to unleash powerful anti-tumour responses and improve the outcome of metastatic solid tumours. Here, we review the principal tumours where research in this field has led to new knowledge and where radioimmunotherapy becomes a reality.

[Hot topics about early clinical trials at ASCO congress 2018: News pathways, new targets, new associations]

Looking at the results of the early trials presented at the 2018 American Society of Clinical Oncology (ASCO) conference can help identify the molecules and strategies that will potentially enter the practices of tomorrow. It is in this spirit that this subject has justified the attention of residents in oncology and the writing of this synthesis. Molecules that can represent breakthrough innovations are presented as well as new therapeutics under development acting on targets already validated in clinical practice and early data of checkpoint inhibitors in combination with different immunomodulators, as well as new strategies for immunotherapies (vaccines and cell therapy).