Automated immunoassay of serum NY-ESO-1 and XAGE1 antibodies for predicting clinical benefit with immune checkpoint inhibitor (ICI) in advanced non-small cell lung cancer.

BACKGROUND: NY-ESO-1 and XAGE1 cancer/testis antigens elicit humoral and cellular immune responses in NSCLC patients. We aimed to predict clinical benefit with ICI monotherapy, using an automated immunoassay of NY-ESO-1/XAGE1 antibodies (Abs). METHODS: This study enrolled 99 NSCLC patients who received nivolumab after chemotherapy, including 21 patients harboring EGFR, ALK, or KRAS alterations. The cutoff value (10 units/mL) of NY-ESO-1 and XAGE1 Ab was determined based on Ab levels in non-malignant controls, and NY-ESO-1/XAGE1 Abs in NSCLC were measured before nivolumab. Differences in PFS and OS between the Ab-positive and Ab-negative groups were retrospectively analyzed using Cox regression analysis after applying inverse probability of treatment weighting (IPTW). RESULTS: NY-ESO-1/XAGE1 Abs were positive in 28 NSCLC, who responded more highly to nivolumab than the Ab-negatives (response rate 50.0% vs. 15.5 %, p < 0.0007). The IPTW-adjusted positives and negatives for NY-ESO-1/XAGE1 Abs were 24.5 and 70.2, respectively. The Ab-positives showed longer IPTW-adjusted PFS (HR = 0.59, 95 % CI: 0.39-0.90, p = 0.014) and IPTW-adjusted OS (HR = 0.51, 95 % CI: 0.32-0.81, p = 0.004) than the Ab-negatives. Among NSCLC harboring driver genes, the Ab-positives (n = 10) showed longer PFS (HR = 0.34, 95 % CI: 0.13-0.89, p = 0.029) and OS (HR = 0.27, 95 % CI: 0.098-0.75, p = 0.012) than the Ab-negatives (n = 11). CONCLUSION: Our immunoassay of NY-ESO-1/XAGE1 Abs is probably useful for predicting the clinical benefit with nivolumab in NSCLC, including those harboring driver genes. These results suggest that our immunoassay may be useful in ICI monotherapy for NSCLC.

Immune checkpoint therapy and response biomarkers in non-small-cell lung cancer: Serum NY-ESO-1 and XAGE1 antibody as predictive and monitoring markers.

Immune checkpoint inhibitors (ICI) are key drugs in systemic therapy for advanced non-small-cell lung cancer (NSCLC) and have recently been incorporated into neoadjuvant and adjuvant settings for surgical resection. Currently, ICI combinations with cytotoxic agents are frequently used in clinical practice, although several ICI clinical trials have failed to produce long-term clinical benefits. Unfortunately, clinical benefit is moderate and limited considering physical and financial burden. Therefore, selecting appropriate patients and regimens for ICI therapy is important, and biomarkers are necessary for their selection. Tumor PD-L1 expression is universally used as a biomarker; however, PD-L1 assays show low analytical validity and reproducibility due to the visual-scoring system by pathologists. Recent tumor immunology studies explore that neoantigens derived from somatic mutations and the collaboration between T and B cells efficiently elicit antitumor responses. This suggests that high tumor mutational burden and T-cell infiltration are predictive biomarkers. However, B cells producing antibody (Ab) remain poorly understood and analyzed as biomarkers. We found that NY-ESO-1 and XAGE1 of cancer-testis antigen frequently elicit spontaneous humoral and cellular immune responses in NSCLC. Serum Ab against these antigens were detected in approximately 25% of NSCLC patients and predicted ICI monotherapy responses. In addition, the Ab levels were decreased with tumor shrinkage after ICI therapy. Thus, NY-ESO-1 and XAGE1 Ab are potentially biomarkers predicting and monitoring response to ICI therapy. For clinical applications, a fully-automated assay system measuring the Ab was developed. Here, we review current ICI therapy, tumor immunology, and biomarkers in NSCLC, and discuss the applicability of the serum biomarkers NY-ESO-1 and XAGE1 Ab.

A novel automated immunoassay for serum NY-ESO-1 and XAGE1 antibodies in combinatory prediction of response to anti-programmed cell death-1 therapy in non-small-cell lung cancer.

BACKGROUND: Anti-programmed cell death-1 (PD-1) antibodies (Abs) are key drugs in non-small-cell lung cancer (NSCLC) treatment; however, clinical benefits with anti-PD-1 monotherapy are limited. We reported that serum Abs against cancer-testis antigens NY-ESO-1 and XAGE1 predicted clinical benefits. We aimed to develop a fully automated immunoassay system measuring NY-ESO-1/XAGE1 Abs. METHODS: Sera from 30 NSCLC patients before anti-PD-1 monotherapy were reacted with recombinant NY-ESO-1 protein- or synthetic XAGE1 peptide-coated magnetic beads. ALP-conjugated Ab and chemiluminescent substrate were added and luminescence measured. These procedures were automated using high sensitivity chemiluminescent enzyme immunoassay (HISCL™). NY-ESO-1/XAGE1 Ab stability was tested under various conditions. Response prediction accuracy was evaluated using area under receiver operating curve (AUROC). RESULTS: HISCL detected specific serum NY-ESO-1/XAGE1 Abs, which levels in ELISA and HISCL were highly correlated. The Ab levels in HISCL were stable at four temperatures, five freeze/thaw cycles, and long-term storage; the levels were not interfered by common blood components. The Ab levels in 15 NSCLC responders to anti-PD-1 monotherapy were significantly higher than those in non-responders and healthy donors. The AUROC was the highest (0.91; 95% CI, 0.78-1.0) in combinatory prediction with NY-ESO-1/XAGE1 Abs. CONCLUSION: Our immunoassay system is useful to predict clinical benefits with NSCLC immune-checkpoint therapy.

Use of B-mode ultrasonography for measuring femoral muscle thickness in dogs.

Assessment of muscle mass is important for evaluating muscle function and rehabilitation outcomes. Ultrasound has recently been successfully used to estimate muscle mass in humans by measuring muscle thickness. This study attempted to standardize procedures for measuring femoral muscle thickness ultrasonographically, as well as quantify the reliability and validity of ultrasound evaluations of muscle thickness compared to measurements made by magnetic resonance imaging (MRI) in dogs. We evaluated the quadriceps femoris (QF), biceps femoris (BF), semitendinosus (ST) and semimembranosus (SM) muscles of 10 clinically healthy Beagle dogs. Scans were taken in 5 different sections divided equally between the greater trochanter and proximal patella. MRI was performed, followed by T1-weighted and contrast-enhanced T1-weighted imaging. Muscle cross-sectional area (CSA) was measured with MRI, and muscle thickness was measured with MRI and ultrasonography. The thickness of the QF, BF and ST muscles as measured by ultrasound at slices 1-3 (from the proximal end to the middle of the femur), 2-4 (middle of the femur) and 2 (more proximal than the middle of the femur), respectively, was correlated with muscle thickness and CSA as measured by MRI. These sites showed a flat interface between muscle and transducer and were situated over belly muscle. No correlation between measurement types was seen in SM muscle. We must confirm this assessment method for various breeds, sizes, ages and muscle pathologies in dogs, thereby confirming that muscle thickness as measured ultrasonographically can reflect muscle function.