Development and Fit-for-Purpose Validation of a Soluble Human Programmed Death-1 Protein Assay

Sex difference in the expression of PD-1 of non-small cell lung cancer

Evidence increasingly indicated that lung cancer incidence in female individuals continue to rise, and women have a higher risk to develop adenocarcinoma than men. Male and female individuals differ in their innate and adaptive immune responses, and there are sex differences in response to the PD-1/PD-L1-dependent blocking immunotherapy. Whether the differential expression of PD-1 between genders affect the response to blocking treatment is currently unknown. In this study, we examined sex differences in serum sPD-1, mPD-1 expression on T cells, and sex hormone levels in non-small cell lung cancer (NSCLC) patients. Our results revealed a higher level of sPD-1 and expression of PD-1 on CD4+T cell in female patients than in male patients; we identified that serum sPD-1 level and the expression of mPD-1 on T cells were significantly reduced in NSCLC; we also found that serum testosterone level increased in female patients compared with control subjects and that increased testosterone downregulated the expression of mPD-1 on T cell. These findings provide a better understanding of the differences in PD-1 expression between genders in NSCLC patients and the effect of sex hormones on PD-1 expression and supply evidence for early lung cancer diagnosis and responsiveness to immune checkpoint inhibitors.

Host STING is essential for the efficacy of anti-PD-1 inhibitors in non-small cell lung cancer

The stimulator of interferon genes (STING) pathway is important for anticancer immune responses. However, the relative contributions of host and tumor STING in anti-PD-1 (programmed cell death protein 1) inhibitor responses in NSCLC are unknown. STING expression in tumor and blood was associated with anti-PD-1 therapy in non-small cell lung cancer (NSCLC) patients; Moreover, loss of PD-1 inhibitor therapeutic potency was demonstrated in STING KO splenocytes and STING KO mice. STING knockdown in tumor cells had no effect. STING on CD8⁺ T cells and host cells, not tumor cells, correlated with clinical effect of Anti-PD1 therapy in NSCLC patients. Finally, adoptive transfer of CD8⁺ T cells restored PD-1 inhibitor anticancer effects. STING in host cells but not in tumor cells, mediates anti-PD-1 inhibitor responses in cancer immunotherapy and could be used to select advantageous NSCLC patients from immunotherapy.

Soluble programmed cell death protein 1 (sPD-1) and the soluble programmed cell death ligands 1 and 2 (sPD-L1 and sPD-L2) in lymphoid malignancies

BACKGROUND

The programmed cell death protein 1 (PD-1) and its ligand 1 and 2 (PD-L1/PD-L2) regulate the immune system, and the checkpoint pathway can be exploited by malignant cells to evade anti-tumor immune response. Soluble forms (sPD-1/sPD-L1/sPD-L2) exist in the peripheral blood, but their biological and clinical significance is unclear.

METHOD

Time-resolved immunofluorometric assay (TRIFMA) and enzyme-linked immunosorbent assay (ELISA) were used to measure sPD-1, sPD-L1, and sPD-L2 levels in serum from 131 lymphoma patients and 22 healthy individuals.

RESULTS

Patients had higher sPD-1 and sPD-L2 levels than healthy individuals. In diffuse large B-cell lymphoma, patients with high International Prognostic Index score had higher sPD-1 levels and sPD-L2 levels correlated with subtype according to cell of origin. Compared to other lymphoma types, follicular lymphoma displayed higher sPD-1 and lower sPD-L1 levels along with lower ligand/receptor ratios.

CONCLUSION

This is the first study to simultaneously characterize pretherapeutic sPD-1, sPD-L1, and sPD-L2 in a variety of lymphoma subtypes. The relation between higher sPD-1 levels and adverse prognostic factors suggests a possible biological role and potential clinical usefulness of sPD-1. Moreover, the reverse expression pattern in follicular lymphoma and T-cell lymphoma/leukemia may reflect biological information relevant for immunotherapy targeting the PD-1 pathway.

Analytical performance of a new automated chemiluminescent magnetic immunoassays for soluble PD-1, PD-L1, and CTLA-4 in human plasma

Current clinically approved biomarkers for the PD-1 blockade cancer immunotherapy are based entirely on the properties of tumour cells. With increasing awareness of clinical responses, more precise biomarkers for the efficacy are required based on immune properties. In particular, expression levels of immune checkpoint-associated molecules such as PD-1, PD-L1, and CTLA-4 would be critical to evaluate the immune state of individuals. Although quantification of their soluble form leased from the membrane will provide quick evaluation of patients’ immune status, available methods such as enzyme-linked immunosorbent assays to measure these soluble factors have limitations in sensitivity and reproducibility for clinical use. To overcome these problems, we developed a rapid and sensitive immunoassay system based on chemiluminescent magnetic technology. The system is fully automated, providing high reproducibility. Application of this system to plasma of patients with several types of tumours demonstrated that soluble PD-1, PD-L1, and CTLA-4 levels were increased compared to those of healthy controls and varied among tumour types. The sensitivity and detection range were sufficient for evaluating plasma concentrations before and after the surgical ablation of cancers. Therefore, our newly developed system shows potential for accurate detection of soluble PD-1, PD-L1, and CTLA-4 levels in the clinical practice.

Critical reagent screening and characterization: benefits and approaches for protein biomarker assays by hybrid LC–MS

In recent years, hybrid ligand-binding assays (LBAs)/LC–MS assays have been increasingly used for quantitation of protein biomarkers in biological matrices. However, unlike in LBAs where the importance of critical reagent screening and characterization is well understood and widely reported, benefits of well-characterized hybrid LC–MS assay reagents are frequently underestimated. Two groups of analyte-specific reagents, binding reagents and assay calibrators, are considered the critical reagents for biomarker assays. In this article, we summarize the similarities and differences of critical reagents used in LBAs and hybrid LC–MS assays, overview the benefits and approaches of critical reagent screening, characterization, antibody conjugation and discuss bioanalytical considerations in hybrid LC–MS assay development for robust measurements of protein biomarkers in biological matrices.

Radiosynthesis and preclinical PET evaluation of 89Zr-nivolumab (BMS-936558) in healthy non-human primates

Cancer immunotherapy, unlike traditional cytotoxic chemotherapeutic treatments, engages the immune system to identify cancer cells and stimulate immune responses. The Programmed Death-1 (PD-1) protein is an immunoinhibitory receptor expressed by activated cytotoxic T-lymphocytes (CTL) that seek out and destroy cancer cells. Multiple cancer types express and upregulate the Programmed Death-Ligand 1 (PD-L1) and 2 (PD-L2) which bind to PD-1 as an immune escape mechanism. Nivolumab is a fully human IgG4 anti-PD-1 monoclonal antibody (mAb) approved for treatment of multiple cancer types. This study reports the preparation and in vivo evaluation of ⁸⁹Zr labeled nivolumab in healthy non-human primates (NHP) as a preliminary study of biodistribution and clearance. The radiochemical and in vivo stabilities of the ⁸⁹Zr complex were shown to be acceptable for imaging. Three naïve NHPs were intravenously injected with tracer only or tracer co-injected with nivolumab followed by co-registered by positron emission tomography (PET) and magnetic resonance imaging (MRI), acquired for eight days following injection. Image-derived standardized uptake values (SUV) were quantified by region of interest (ROI) analysis. Radioactivity in the spleen was significantly reduced by addition of excess nivolumab compared to the tracer only study at all imaging time points. Liver uptake of the radiotracer was consistent as a clearance organ with minimal signal from other tissues: lung, muscle, brain, heart, and kidney. The results indicate specific biodistribution to the spleen, which can be blocked by co-administration of excess nivolumab. Distribution to other organs is consistent with elimination pathways of antibodies, with primary clearance through the liver.

Fit-for-purpose biomarker immunoassay qualification and validation: three case studies

AIM

To improve on the efficiency of biomarker assay readiness, and for reliable biomarker data to support three drug programs, we implemented a fit-for-purpose approach, qualifying two biomarker assays and validating a third. Results/methodology: The qualification strategy and selection of experiments for two exploratory biomarkers (CXCL1, CCL19) was determined by the intended use of the biomarker data. The third biomarker, IL-6, was validated as the data would be used in monitoring patient safety during dose-escalation studies in a Phase I trial. All three assays passed a priori acceptance criteria.

CONCLUSION

These assays highlight strategies and methodologies for a fit-for-purpose approach. Minimum qualification, full qualification and validation were chosen and supported programs at different stages of drug development.

Increase in soluble PD-1 is associated with prolonged survival in patients with advanced EGFR-mutated non-small cell lung cancer treated with erlotinib

OBJECTIVES

The central immune co-inhibitory programmed cell death receptor/ligand 1 (PD-1/PD-L1) pathway plays a key role in tumor immune evasion in non-small cell lung cancer (NSCLC). Soluble PD-1 (sPD-1) can be detected in the blood, and preclinical evidence suggests that sPD-1 blocks PD-1/-L1 interaction and improves anti-tumor immunity. The present study compares the concentration of sPD-1 in the serum of advanced NSCLC patients with Epidermal Growth Factor Receptor (EGFR) mutation prior to erlotinib treatment and at the time of progression and correlates these results to patient outcome.

MATERIALS AND METHODS

Blood samples from 38 patients with EGFR-mutated advanced NSCLC treated with erlotinib were analyzed for sPD-1 by sandwich ELISA. EGFR mutational status was assessed in circulating tumor DNA (ctDNA) and tumor biopsies.

RESULTS

sPD-1 could be detected in 21% of patients prior to erlotinib treatment, and at disease progression in 37% (p=0.015). An increase in sPD-1 during erlotinib therapy was found in 34%, a decrease in 8% and no change in 58% of patients. An increase in sPD-1 during treatment was associated with prolonged progression-free (adjusted HR 0.32, p=0.013) and overall survival (adjusted HR 0.33, p=0.006), but not associated with the emergence of EGFR T790M mutation in ctDNA at progression or any clinicopathological factors.

CONCLUSION

Patients with an increase in sPD-1 during erlotinib treatment have a more favorable outcome. Our results emphasize the vast clinical impact of the PD-1/PD-L1 axis, and support the existing preclinical evidence in the bioactive function of sPD-1.