First-line pembrolizumab plus chemotherapy for advanced/metastatic esophageal cancer: 1-year extended follow-up in the Japanese subgroup of the phase 3 KEYNOTE-590 study.

BACKGROUND: First-line pembrolizumab plus chemotherapy (pembrolizumab-chemotherapy) demonstrated improved efficacy and a manageable safety profile versus placebo plus chemotherapy (placebo-chemotherapy) in the subgroup analysis of Japanese patients with advanced/metastatic esophageal cancer in KEYNOTE-590 at a median follow-up of 24.4 months. Longer-term data from the Japanese subgroup analysis of KEYNOTE-590 are reported. METHODS: Patients were randomly assigned 1:1 to pembrolizumab 200 mg or placebo every 3 weeks for ≤ 35 cycles plus chemotherapy (cisplatin 80 mg/m2 and 5-fluorouracil 800 mg/m2/day). Endpoints included overall survival (OS) and progression-free survival (PFS; investigator-assessed per RECIST v1.1; dual primary) and safety (secondary). Early tumor shrinkage (ETS) and depth of response (DpR) were assessed post hoc. RESULTS: Overall, 141 patients were enrolled in Japan. As of July 9, 2021, median follow-up was 36.6 months (range, 29.8-45.7). Pembrolizumab-chemotherapy showed a trend toward favorable OS (hazard ratio [HR], 0.70; 95% confidence interval [CI] 0.47-1.03) and PFS (0.57; 0.39-0.83) versus placebo-chemotherapy. In the pembrolizumab-chemotherapy group, patients with ETS ≥ 20% (55/74; 74.3%) versus < 20% (19/74; 25.7%) had favorable OS (HR, 0.23; 95% CI 0.12-0.42) and PFS (0.24; 0.13-0.43). Patients with DpR ≥ 60% (31/74; 41.9%) versus < 60% (43/74; 58.1%) had favorable OS (HR, 0.37; 95% CI 0.20-0.68) and PFS (0.24; 0.13-0.43). Grade 3-5 treatment-related adverse events occurred in 55/74 patients (74.3%) with pembrolizumab-chemotherapy and 41/67 patients (61.2%) with placebo-chemotherapy. CONCLUSIONS: With longer-term follow-up of Japanese patients with advanced/metastatic esophageal cancer, efficacy continued to favor pembrolizumab-chemotherapy compared with placebo-chemotherapy, with no new safety signals observed. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT03189719.

Second-line pembrolizumab versus chemotherapy in Japanese patients with advanced esophageal cancer: subgroup analysis from KEYNOTE-181.

BACKGROUND: Safe and effective treatments for advanced esophageal cancer are an unmet need in Japan. We report results of a subgroup analysis of Japanese patients enrolled in KEYNOTE-181, a randomized, open-label, phase 3 study of pembrolizumab versus chemotherapy as second-line therapy for patients with advanced or metastatic esophageal cancer whose disease progressed after standard first-line therapy. METHODS: Patients were randomly assigned 1:1 to receive pembrolizumab 200 mg every 3 weeks or investigator's choice of paclitaxel, docetaxel, or irinotecan. Efficacy was evaluated in all Japanese patients and in those with programmed death ligand 1 combined positive score ≥ 10. RESULTS: Of the 152 Japanese patients enrolled (pembrolizumab, n = 77; chemotherapy, n = 75), 150 (98.7%) had squamous cell carcinoma and 79 (52.0%) had combined positive score ≥ 10. At the final analysis, median overall survival was improved among all patients (12.4 vs 8.2 months with pembrolizumab and chemotherapy, respectively; hazard ratio, 0.68; 95% CI 0.48-0.97) and patients with combined positive score ≥ 10 (12.6 vs 8.4 months; hazard ratio, 0.68; 95% CI 0.42-1.10). Fewer patients had any-grade (74.0% vs 95.9%) or grade 3-5 (16.9 vs 50.0%) treatment-related adverse events with pembrolizumab than with chemotherapy. CONCLUSION: Consistent with the global trial results, second-line pembrolizumab therapy showed a survival benefit and a favorable safety profile compared with chemotherapy in Japanese patients with advanced esophageal cancer.

Immunoenzymometric assay for a small molecule,11-deoxycortisol, with attomole-range sensitivity employing an scFv-enzyme fusion protein and anti-idiotype antibodies.

To overcome the sensitivity limit in immunoassays for small molecules (haptens), we established a noncompetitive immunoenzymometric assay (IEMA) format that can detect attomole-range hapten molecules. We selected 11-deoxycortisol (11-DC; Mr 346.5), a corticosteroid serving a diagnostic index for pituitary-adrenal function, as a model target hapten. A fusion of a single-chain Fv fragment (scFv) specific for 11-DC and alkaline phosphatase (ALP) was generated for use as an enzyme-labeled antibody, instead of the conventional chemically linked enzyme-antibody conjugates. After binding reaction of 11-DC and fixed amounts of the fusion protein (scFv-ALP), the unbound fusion protein was removed by incubation with a mouse beta-type anti-idiotype antibody recognizing the scFv paratope. These complexes were captured by magnetic separation using anti-mouse IgG antibody-coated magnetic beads. Following magnetic sedimentation of the beads, immune complexes of scFv-ALP and 11-DC remained in the supernatant were further purified by capture on microtiter plates with immobilized alpha-type anti-idiotype antibody. As measured fluorometrically, ALP activity from bound immune complexes on the plates increased with increasing 11-DC, which is characteristic of a noncompetitive relationship. This IEMA afforded an extremely low detection limit (20 amol/assay), a very wide measurable range, and practical specificity. The plasma 11-DC levels determined for healthy subjects were validated as reliable.